Targeted photoacoustic compounds

Abstract

The present invention relates to a targeted photoacoustic system for use in the treatment of skin or hair-associated diseases or conditions and / or for the removal of tattoos. The invention also relates to compositions comprising the targeted photoacoustic system, devices and kits for delivering the targeted photoacoustic system, and techniques for manufacturing the targeted photoacoustic system.

Description

[0001] TARGETED PHOTOACOUSTIC COMPOUNDS

[0002] FIELD OF INVENTION

[0003] The present invention relates to a targeted delivery system for use in the treatment of skin- or hair-associated diseases or conditions and / or for the removal of tattoos. The invention also relates to compositions comprising the targeted delivery system, devices and kits for delivering the targeted delivery system, and techniques for manufacturing the targeted delivery system.

[0004] BACKGROUND OF INVENTION

[0005] Photodynamic therapy is a treatment paradigm that combines the use of light energy with a photosensitizer. A photosensitizer is a chemical that remains inert until activated by the light energy, which is usually supplied by a laser. However, in therapeutic or cosmetic applications, the photosensitizer may become toxic or in some way damaging to surrounding cells and tissues once activated. The photoacoustic effect (also known as the optoacoustic effect) is a known phenomenon wherein absorption of light causes a photoacoustic substance to release energy in the form of vibrations or sound waves. Optoacoustic or photoacoustic therapies are accordingly a subset of photodynamic therapies.

[0006] Roberts etal discloses an optoacoustic technique to image cancer cells. The technique uses a pH low insertion peptide conjugated to a dark quencher. Dark quencher dyes, as the name suggests, are non-fluorescent (dark) dyes which were developed to quench fluorophores. In the process, they emit energy via molecular vibration rather than emission of photons. Black Hole Quencher 1 (BHQ1) is an example of a dark quencher.

[0007] Similarly, Wang et al discloses the in situ destruction of tumour cell nuclei by photoacoustic therapy. The therapy makes use of a photoacoustic polymer consisting of a nucleus targeting TAT peptide, hydrophilic chain poly (N, N-dimethylacrylamide)(PDMA), and near-infrared (NIR) light absorbing agent (hCyR). These constituents self-assemble to form nanoparticles which aggregate in the nucleus of the target cell, allowing up to 80% cell death to be achieved via the photoacoustic effect when stimulated with light of a suitable frequency and intensity. Zhong et al discloses a related technique making use of cancer-targeting nanoparticles comprising indocyanine green, phospholipid-polyethylene glycol and folic acid.

[0008] For the purposes of in vivo therapies targeting skin conditions and diseases, the human epidermis is known to have an “optical window” of between around 600 and 1300nm through which light can pass without significant attenuation to the dermis (Anderson and Parrish). Photodynamic therapies may accordingly make use of frequencies of light within this window.

[0009] Various targeting agents are presently known in the art to target and localise compounds to specific cells and tissues. These include aptamers, antibodies, Fabs, or nanobodies. Aptamers, which can be oligomers of artificial ssDNA, RNA, XNA, or peptides, are known for their high specificity in binding to target molecules or a family of related molecules. Methods for producing aptamers, including the “Systematic Evolution of Ligands by Exponential Enrichment” (SELEX) process, are well-established in the art. SELEX is a combinatorial technique in molecular biology for generating single-stranded DNA or RNA oligonucleotides, commonly referred to as aptamers, that specifically bind to target ligands. It is widely used for the selection of aptamers targeting specific cells, such as tumour cells or tissues.

[0010] The SELEX process begins with library preparation, where a diverse library of randomized oligonucleotide sequences is synthesized, serving as the starting material for selecting specific aptamers that bind to target cells. Target preparation involves immobilizing target cells on a suitable substrate for aptamer selection. The binding and partitioning step involves incubating the oligonucleotide library with the immobilized target cells under conditions that favour aptamer binding to cell surface markers, followed by washing away unbound sequences and eluting bound aptamers.In the amplification step, eluted aptamers are amplified using PCR for DNA aptamers or RT-PCR followed by PCR for RNA aptamers, enriching the pool for high-affinity sequences. This iterative selection process, typically involving 5-15 cycles of binding, washing, elution, and amplification, progressively enriches aptamers with the highest specificity and affinity. Sequence analysis and characterization follow, where the sequences of enriched aptamers are determined using high-throughput sequencing, and top candidates are synthesized for further evaluation of binding efficiency and specificity.

[0011] In addition to nucleotide aptamers, peptide aptamers can be selected and targeted to specific tissues using both experimental and in silico approaches. Experimentally, peptide aptamers can be identified through techniques such as phage display, which screens large peptide libraries against target molecules or cells. In silico methods involve computational modelling and simulations to predict peptide binding affinities and specificities, significantly accelerating the identification of effective targeting peptides.

[0012] Various skin-related conditions and diseases are known to be in need of improved treatment modalities including the treatment of acne, scars, stretch marks, hyperhidrosis, removal of skin tags, or cellulite, or to facilitate skin-tightening, as well as improved skin cancer therapies and the like. Furthermore, hair-related treatments including hair removal, colour treatment and hair regrowth, particularly in subjects with fair hair or fair skin would benefit from improved treatment options.

[0013] Additionally, the persistence and stability of tattoos is a well-known phenomenon, requiring a specialised tattoo removal process where the tattoo has become unwanted. However, the exact mechanics behind such persistence has only recently become clearly understood. It has long been known that ink is ingested by macrophages and localised into vacuoles. The macrophages, being unable to digest the ink, remain in place in the dermis. Recently, Baranska et al demonstrated that populations of macrophages turn over in time, with younger cells re-uptaking ink released by dying cells. This process of continual release and reuptake of ink explains the otherwise-inexplicable longevity of tattoos, which would intuitively be expected to fade completely over the course of a few years due to macrophage turnover.

[0014] Tattoo removal, as well known in the art, relies principally on the dilution or destruction of ink injected into the dermis during the tattooing process. Historically, techniques to remove a tattoo involved penetrating or excising the tissue above the dermis and then either physically removing the dermal tissue or injecting / applying a chemical agent that targets the tattoo ink for removal. With the invention of lasers, it was realised that a coherent beam of the correct frequency would render the upper layers of skin optically transparent while still allowing the beam to interact with the ink itself. Presently, the most common tattoo removal procedures make use of pulsed lasers of different frequencies tuned to the absorption spectra of the ink and the optical window of the skin. However, these techniques rely on thermal decomposition of the ink and are known to damage surrounding tissue. As a result, these techniques are also extremely painful to the subject being treated. Furthermore, this damage results in whitening of the affected area, thereby facilitating the requirement of repeat treatments with a waiting period between treatments. These techniques are also limited in their efficacy when used on ink colours closer in absorbance to that of the skin itself (such as red and yellow) as well on lighter-colored inks that are more reflective, such as purple and yellow ink.

[0015] Given the above, there is a need in the present art for improved compositions and techniques to target skin and hair-related diseases and conditions including for treatment of acne, scars, stretch marks, hyperhidrosis, removal of skin tags, or cellulite, or to facilitate skin-tightening, as well as improved skin cancer therapies, as well as for hair-removal, hair regrowth and hair colour treatment, and / or for removal of tattoos.

[0016] SUMMARY OF INVENTION

[0017] According to a first aspect of the invention, there is provided a targeted delivery system comprising or consisting of:

[0018] at least one targeting motif and / or at least one tag for targeting at least one cell population;at least one compound selected from the group consisting of at least one chromophore or at least one photoacoustic compound having an absorption maximum within the optical window of the skin, preferably an absorption maximum selected from between 500 nm and 1350 nm or any wavelength therebetween;

[0019] at least one delivery system,

[0020] wherein the at least one targeting motif and / or the at least one tag is conjugated to the at least one compound with at least one linker, and / or is displayed on a surface of the at least one delivery system, and

[0021] wherein the at least one compound is encapsulated or comprised within the at least one delivery system.

[0022] In a particular embodiment of the first aspect of the invention, the targeted delivery system comprises or consists of:

[0023] at least one targeting motif and / or at least one tag for targeting at least one cell population;

[0024] at least one compound selected from the group consisting of at least one chromophore or at least one photoacoustic compound having an absorption maximum within the optical window of the skin, preferably an absorption maximum selected from between 500 nm and 1350 nm or any wavelength therebetween, conjugated to the at least one targeting motif and / or the at least one tag with at least one linker; and at least one delivery system,

[0025] wherein the targeting motif and / or tag-conjugated compound is encapsulated or comprised within the at least one delivery system such that the targeting motif and / or tag is displayed on its surface.

[0026] In a further particular embodiment of the first aspect of the invention, the targeted delivery system comprises or consists of:

[0027] at least one targeting motif and / or tag for targeting at least one cell population; at least one compound selected from the group consisting of at least one chromophore or at least one photoacoustic compound having an absorption maximum within the optical window of the skin, preferably an absorption maximum selected from between 500 nm and 1350 nm or any wavelength therebetween; andat least one delivery system functionalised to display the at least one targeting motif and / or tag on its surface and encapsulating the at least one compound.

[0028] In yet a further particular embodiment of the first aspect of the invention, the targeted delivery system comprises or consists of:

[0029] at least one targeting motif conjugated with at least one linker to at least one tag;

[0030] at least one compound selected from the group consisting of at least one chromophore or at least one photoacoustic compound having an absorption maximum within the optical window of the skin, preferably an absorption maximum selected from between 500 nm and 1350 nm or any wavelength therebetween; and

[0031] at least one delivery system functionalised to display the conjugated targeting motif and tag on its surface and encapsulating the at least one compound.

[0032] The at least one tag may be included to improve the efficacy, stability, and bioavailability of the targeted delivery system.

[0033] The at least one photoacoustic compound may be a synthesized and / or a natural quencher.

[0034] For example, the quencher may be a dark quencher such as a Black Hole Quencher (BHQ) selected from the group comprising or consisting of Black Hole Quencher-1 (BHQ-1), BHQ-2, BHQ-3, Black Berry Quencher-650 (BBQ-650), BMN Quencher 460 (BMN-Q460), BMN-Q535, BMN-Q1, BMN-Q2, BMN-Q590, BMN-Q620, BNM-Q651 or Dabcyl.

[0035] Alternatively, the chromophore or photoacoustic compound may be a nanoparticle or nanofiber. For example, the chromophore or photoacoustic compound may be a carbon or gold nanoparticle or carbon nanofiber. For example, the carbon nanoparticle or nanofiber may be a carbon black nanoparticle or nanofiber and may be formulated as a nanoparticle or nanofiber powder, a nanoparticle or nanofiber cluster or for delivery within a patch embedded with the nanoparticles or nanofibers. For example, the nanoparticles or nanofibers may be formulated in a delivery system comprising apolymer hydrogel such as a hydrogel patch embedded with the nanoparticles or nanofibers. Alternatively, the nanoparticles or nanofibers may be formulated in a lipid-based delivery system, such as lipid nanoparticles (LNPs), liposomes, or other lipid-like vesicle carriers including a nanoemulsion. It is to be appreciated that gold nanoparticles or carbon black nanoparticles or nanofibers have a dual role as a quencher and an enhancer of optical properties of a photoacoustic compound.

[0036] Here it should be understood that the purpose of the photoacoustic compound is to induce a photoacoustic effect upon activation by a suitable light source. The photoacoustic effect would be understood by those skilled in the art as causing mechanical disruption of the targeted tissue without the thermal effects, emissions, or scattering typically associated with conventional photosensitizers in photodynamic therapy.

[0037] The at least one targeting motif and / or tag may be selected from the group consisting of nucleotide aptamers, peptide aptamers, peptides, Peptide Nucleic Acid Oligomers (PNAOs), L-ribonucleic acid aptamer (or Spiegelmer), antibodies, antibody fragments and nanobodies.

[0038] It is to be appreciated that the at least one targeting motif peptide or tag may be D-enantiomer amino acid peptides or cyclic peptides including head-to-tail cyclic peptides through chemical conjugation between the N-terminal NH₂ with the C-terminal COOH such as through 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) coupling or via side chains including Cysteine (Cys) - Lysine (Lys) disulphide linkage.

[0039] In particular in one embodiment of the first aspect of the invention, the at least one targeting motif may be a nucleotide aptamer, more preferably a nucleotide aptamer comprising or consisting of a nucleotide sequence having at least 75%, or at least 80% sequence identity, or at least 85% sequence identity, or at least 90% sequence identity, or at least 95% sequence identity, or up to 100 % sequence identity to any one of SEQ ID NOS: 1-119, or any sequence identity therebetween or any nucleotide sequence capable of hybridising under stringent conditions to any one of SEQ ID NOS: 1-119 or a nucleotide sequence having at least 75%, or at least 80% sequence identity, or atleast 85% sequence identity, or at least 90% sequence identity, or at least 95% sequence identity, or up to 100 % sequence identity of any one of SEQ ID NOS: 1-119 or any sequence identity therebetween. The nucleotide sequence may be adapted to form a Peptide Nucleic Acid Oligomer (PNA), or L-ribonucleic acid aptamer.

[0040] For example, the at least one targeting motif may be a nucleotide aptamer comprising or consisting of a nucleotide sequence having at least 75%, or at least 80% sequence identity, or at least 85% sequence identity, or at least 90% sequence identity, or at least 95% sequence identity, or up to 100 % sequence identity, or any sequence identity therebetween of GAAGAGTCGATGTAACGTTTTTTCGCACGATAATAGGGACGTGAGTCAGACA

[0041] (SEQ ID NO: 8) or any nucleotide sequence capable of hybridising under stringent conditions to SEQ ID NO: 8 or a nucleotide sequence having at least 75%, or at least 80% sequence identity, or at least 85% sequence identity, or at least 90% sequence identity, or at least 95% sequence identity, or up to 100 % sequence identity, or any sequence identity therebetween to SEQ ID NO: 8, or any nucleotide sequence capable of hybridising under stringent conditions to SEQ ID NO: 8 or a nucleotide sequence having at least 75%, or at least 80% sequence identity, or at least 85% sequence identity, or at least 90% sequence identity, or at least 95% sequence identity, or up to 100 % sequence identity, or any sequence identity therebetween. The nucleotide sequence may be adapted to form a Peptide Nucleic Acid Oligomer (PNA), or L-ribonucleic acid aptamer.

[0042] Stringent conditions for hybridisation are well known in the art and are described in, for example, Sambrook etal., Molecular Cloning: A Laboratory Manual, 2021.

[0043] In another embodiment of the first aspect of the invention, the targeting motif may be a peptide aptamer, preferably a peptide aptamer comprising or consisting of an amino acid sequence having at least 75%, or at least 80% sequence identity, or at least 85% sequence identity, or at least 90% sequence identity, or at least 95% sequence identity, or up to 100 % sequence identity, or any sequence identity therebetween to any one of SEQ ID NOS: 120-135:

[0044] SEQ ID NO: 120: RRRWCKRRRVVAAEEEEGYEQDPWGVKWWY,SEQ ID NO: 121 RRRWCKRRRVVAAEEEEGYEQDPWGVKWWYC,

[0045] SEQ ID NO: 122 CYEQDPWGVKWWYVVAAEEEEGRRRWCKRRR,

[0046] SEQ ID NO: 123 RRRWCKRRRVVAAEEEEGTKPR,

[0047] SEQ ID NO: 124 RRRWCKRRRVVAAEEEEGTKPRC,

[0048] SEQ ID NO: 125 RRRWCKRRRVVAAEEEEGTKPRC,

[0049] SEQ ID NO: 126 RRRWCKRRRVVAAEEEEGWQSNPQSNSS,

[0050] SEQ ID NO: 127 WQSNPQSNSS,

[0051] SEQ ID NO: 128 WQPPRQLCANV,

[0052] SEQ ID NO: 129 RRRWCKRRRVVAAEEEEGWQPPRQLCANV,

[0053] SEQ ID NO: 130 YEQDPWGVKWWY,

[0054] SEQ ID NO: 131 TKPR,

[0055] SEQ ID NO: 132 QANWNDNEQEW,

[0056] SEQ ID NO: 133 RRRWCKRRRVVAAEEEEGQANWNDNEQEW,

[0057] SEQ ID NO: 134 AHFGE, or

[0058] SEQ ID NO: 135 RRRWCKRRRVVAAEEEEGAHFGE.

[0059] More particularly, the peptide aptamer may be for macrophage targeting.

[0060] In one particular embodiment of the invention, the peptide sequences for macrophage targeting are any one or more of the peptide sequences set out in SEQ ID NOs: 23 to 38, or any amino acid sequence having at least 75%, or at least 80% sequence identity, or at least 85% sequence identity, or at least 90% sequence identity, or at least 95% sequence identity, or up to 100 % sequence identity, or any sequence identity therebetween to any one of the peptide sequences SEQ ID NOs 23 to 38, but further have 100% sequence identity to the amino acids shown in bold type:

[0061] SEQ ID NO: 120 RRRWCKRRRVVAAEEEEGYEQDPWGVKWWY,

[0062] SEQ ID NO: 121 RRRWCKRRRVVAAEEEEGYEQDPWGVKWWYC,

[0063] SEQ ID NO: 122 CYEQDPWGVKWWYVVAAEEEEGRRRWCKRRR,

[0064] SEQ ID NO: 123 RRRWCKRRRVVAAEEEEGTKPR,

[0065] SEQ ID NO: 124 RRRWCKRRRVVAAEEEEGTKPRC,

[0066] SEQ ID NO: 125 RRRWCKRRRVVAAEEEEGTKPRC,

[0067] SEQ ID NO: 126 RRRWCKRRRVVAAEEEEGWQSNPQSNSS,

[0068] SEQ ID NO: 127 WQSNPQSNSS,SEQ ID NO: 128: WQPPRQLCANV,

[0069] SEQ ID NO: 129: RRRWCKRRRVVAAEEEEGWQPPRQLCANV,

[0070] SEQ ID NO: 130: YEQDPWGVKWWY,

[0071] SEQ ID NO: 131: TKPR,

[0072] SEQ ID NO: 132: QANWNDNEQEW,

[0073] SEQ ID NO: 133: RRRWCKRRRVVAAEEEEGQANWNDNEQEW,

[0074] SEQ ID NO: 134: AHFGE, or

[0075] SEQ ID NO: 135: RRRWCKRRRVVAAEEEEGAHFGE.

[0076] For example, the at least one targeting motif or the at least one tag may be a skinpenetrating peptide, preferably a peptide comprising or consisting of an amino acid sequence having at least 75%, or at least 80% sequence identity, or at least 85% sequence identity, or at least 90% sequence identity, or at least 95% sequence identity, or up to 100 % sequence identity, or any sequence identity therebetween to any one of SEQ ID NOS: 136-142.

[0077] The at least one targeting motif or the at least one tag may be a peptide for macrophage targeting such as: Macrophage Colony Stimulating Factor (M-CSF) (Stanley, P. E., & Schreiber, D. R. (1993). Colony-stimulating factor-1: A central regulator of macrophage development and function. Immunology Today, 14(11), 437-440); CD163 (Gordon, S., & Taylor, M. E. (2005). Mannose: The key to initiating innate immune responses. Nat. Rev. Immunol., 5(12), 940-952); Scavenger Receptor A (SR-A) (Mukhopadhyay, S., & Hussain, S. P. (2005). Scavenger receptors in innate immunity: Eating up the good, the bad and the ugly. Trends Immunol., 26(11), 649-654); C-Type Lectin Receptor 2 (CLE2) (Geijtenbeek, T. H., & Gringhuis, S. (2009). C-type lectins: Sensing and signaling in innate immune defense. Cell. Mol. Life Sci., 66(10), 1677-1692); Human Antibodies (Chi, E. Y., & Abraham, E. H. (2003). Tuftsin: A novel immunomodulatory peptide involved in innate immunity and inflammation. J. Leukoc. Biol., 74(4), 881-886).

[0078] The at least one targeting motif may be a peptide sequence for hair follicle targeting selected from the group comprising or consisting of amino acid sequences having at least 75%, or at least 80% sequence identity, or at least 85% sequence identity, or at least 90% sequence identity, or at least 95% sequence identity, or up to 100 %sequence identity, or any sequence identity therebetween to any one of SEQ ID NOs: 150-219.

[0079] Sequence SEQ ID NO:

[0080] C16-GSGRRRWCKRRRWAEEEEGAFTPAKT 150

[0081] C14-GSGRRRWCKRRRWAEEEEGAFTPAKT 151

[0082] C16-GSGRRRWCKRRRWAEEEEGAFTPVKT 152

[0083] C14-GSGRRRWCKRRRWAEEEEGAFTPVKT 153

[0084] C16-GSGRRRWCKRRRWAEEEEGVFTPAKT 154

[0085] C14-GSGRRRWCKRRRWAEEEEGVFTPAKT 155

[0086] C16-GSGRRRWCKRRRWAEEEEGSFTPAKT 156

[0087] C14-GSGRRRWCKRRRWAEEEEGSFTPAKT 157

[0088] C16-GSGRRRWCKRRRWAEEEEGAFTPAKS 158

[0089] C14-GSGRRRWCKRRRWAEEEEGAFTPAKS 159

[0090] C16-GSGRRRWCKRRRWAEEEEGAFTSAKT 160

[0091] C14-GSGRRRWCKRRRWAEEEEGAFTSAKT 161

[0092] C16-GSGRRRWCKRRRWAEEEEGAFSPAKT 162

[0093] C14-GSGRRRWCKRRRWAEEEEGAFSPAKT 163

[0094] C16-GSGRRRWCKRRRWAEEEEGVFTPVKT 164

[0095] C14-GSGRRRWCKRRRWAEEEEGVFTPVKT 165

[0096] C16-GSGRRRWCKRRRWAEEEEGSFTPAKS 166

[0097] C14-GSGRRRWCKRRRWAEEEEGSFTPAKS 167

[0098] C16-GSGRRRWCKRRRWAEEEEGAFTSVKT 168

[0099] C14-GSGRRRWCKRRRWAEEEEGAFTSVKT 169

[0100] C16-GSGRRRWCKRRRWAEEEEGAFSPVKT 170

[0101] C14-GSGRRRWCKRRRWAEEEEGAFSPVKT 171

[0102] C16-GSGRRRWCKRRRWAEEEEGFTPAKT 172

[0103] C14-GSGRRRWCKRRRWAEEEEGFTPAKT 173

[0104] C16-GSGRRRWCKRRRWAEEEEGAFTPAK 174

[0105] C14-GSGRRRWCKRRRWAEEEEGAFTPAK 175

[0106] C16-GSGRRRWCKRRRWAEEEEGFTPAK 176

[0107] C14-GSGRRRWCKRRRWAEEEEGFTPAK 177

[0108] C16-GSGRRRWCKRRRWAEEEEGASSHTISF 178

[0109] C14-GSGRRRWCKRRRWAEEEEGASSHTISF 179

[0110] C16-GSGRRRWCKRRRWAEEEEGASSHTISY 180

[0111] C14-GSGRRRWCKRRRWAEEEEGASSHTISY 181

[0112] C16-GSGRRRWCKRRRWAEEEEGASSHTISL 182

[0113] C14-GSGRRRWCKRRRWAEEEEGASSHTISL 183

[0114] C16-GSGRRRWCKRRRWAEEEEGASSHTVSF 184

[0115] C14-GSGRRRWCKRRRWAEEEEGASSHTVSF 185

[0116] C16-GSGRRRWCKRRRWAEEEEGAFPQPPQR 186

[0117] C14-GSGRRRWCKRRRWAEEEEGAFPQPPQR 187

[0118] C16-GSGRRRWCKRRRWAEEEEGFPPQPPQR 188

[0119] C14-GSGRRRWCKRRRWAEEEEGFPPQPPQR 189

[0120] C16-GSGRRRWCKRRRWAEEEEGAFPQPPHR 190

[0121]

[0122] C14-GSGRRRWCKRRRWAEEEEGAFPQPPHR 191C16-GSGRRRWCKRRRWAEEEEGAFPHPPQR: 192 C14-GSGRRRWCKRRRWAEEEEGAFPHPPQR: 193 C16-GSGRRRWCKRRRWAEEEEGASPWIPAV 194 C14-GSGRRRWCKRRRWAEEEEGASPWIPAV 195 C16-GSGRRRWCKRRRWAEEEEGASPWIPW 196 C14-GSGRRRWCKRRRWAEEEEGASPWIPW 197 C16-GSGRRRWCkRRRWAEEEE 198 C14-GSGRRRWCKRRRWAEEEEGASPWVPAV 199 C16-GSGRRRWCKRRRWAEEEEGASPWIPAF 200 C14-GSGRRRWCKRRRWAEEEEGASPWIPAF 201 C16-GSGRRRWCKRRRWAEEEEGAACSSSPSKHCG 202 C14-GSGRRRWCKRRRWAEEEEGAACSSSPSKHCG 203 C16-GSGRRRWCKRRRWAEEEEGAACSSSPSKHSG: 204 C14-GSGRRRWCKRRRWAEEEEGAACSSSPSKHSG 205 C16-GSGRRRWCKRRRWAEEEEGAACSSSPSKHCA 206 C14-GSGRRRWCKRRRWAEEEEGAACSSSPSKHCA 207 C16-GSGRRRWCKRRRWAEEEEGACSSSPSKHC 208 C14 -GSGRRRWCkRRRWAEEEEGAC 209 C16-GSGRRRWCkRRRWAEEE^ 210 C14-GSGRRRWCKRRRWAEEEEGACSSSPSKHS: 211 C16-GSGRRRWCKRRRWAEEEEGACSSSPSKQC 212 Ci4-QsgRRF^cKRRRWAEEEEGACSSSPSkQC 213 C16-GSGRRRWCKRRRVVAEEEEGAACSSSSSKHCG P214 CiA-GSGRRRWCkRRRWAEEEEGAACSS 215 C16 GSGRRRWCkRRRWAEEEEGAAC 216 C14-GSGRRRWCkRRRWAEEEEGA^ 217 C16 -GSGRRRWCKRRRWAEEEEGAACSSSSSKHCA 218

[0123]

[0124] C14-GSGRRRWCKRRRWAEEEEGAACSSSSSKHCA 219

[0125] In a further possible embodiment of the first aspect of the invention, the at least one tag may be a skin penetrating peptide tag, thereby to facilitate transdermal transport of the photoacoustic compound.

[0126] For example, the skin penetrating peptide tag may be conjugated by at least one linker to the at least one targeting motif which is in the form of a peptide for macrophage targeting or a peptide for hair follicle targeting. The skin penetrating peptide tag or conjugated targeting motif and skin penetrating peptide tag may be displayed on a surface of the delivery system.

[0127] Non-limiting examples of skin penetrating peptide tags are: Trans-Activator of Transcription (TAT) peptides; penetratin; Cell-penetrating peptides (CPPs); arginine-rich peptides; transportan; pVEC; Antennapedia (Antp) peptides; R8; and R9. It is to be appreciated that such skin-penetrating peptide tags are known to have a high efficacy in promoting the absorption of peptides through the skin barrier, making them particularly valuable in dermatological applications and transdermal drug delivery systems.

[0128] In particular, the peptide tag sequences for skin penetration enhancement may be any one or more of:

[0129] TAT peptide -YGRKKRRQRRR (SEQ ID NO: 136),

[0130] Penetratin - RQIKIWFQNRRMKWKK (SEQ ID NO: 137),

[0131] Transportan - GWTLNSAGYLLGKINLKALAALAKKIL (SEQ ID NO: 138),

[0132] pVEC - LLIILRRRIRKQAHAHSK (SEQ ID NO: 139),

[0133] Antennapedia (Antp) peptide - RQIKIWFQNRRMKWKK (SEQ ID NO: 140),

[0134] R8 - RRRRRRRR (SEQ ID NO: 141),

[0135] R9 - RRRRRRRRR (SEQ ID NO: 142),

[0136] or any amino acid sequence having at least 75%, or at least 80% sequence identity, or at least 85% sequence identity, or at least 90% sequence identity, or at least 95% sequence identity, or up to 100 % sequence identity, or any sequence identity therebetween to any one of the peptide sequences SEQ ID NOs 136 to 142 above.

[0137] The at least one tag may be a lipophilic tag and / or a heterobifunctional tag. For example, the at least one tag may function to enhance tissue penetration, visualization, targeting (including macrophage targeting), cellular uptake and / or incorporation into the delivery system.

[0138] The at least one linker may be selected from the group comprising or consisting of polyethylene glycol (PEG) linker, a glycine-serine (GS) linker, a maleimide linker, a fatty acid linker, a hyaluronic acid linker, a succinic acid linker, a peptide linker, or a cleavable linker, or any combination thereof.

[0139] In this context, it is to be appreciated that that the PEG linker enhances solubility and bioavailability, and reduces immunogenicity. The GS linker provides flexibility and reduces steric hindrance, facilitating the biological activity of a peptide. The malemidelinkers are used for stable conjugation to thiol groups, such as those in cysteines. The fatty acid linkers, such as palmitic acid, are used for membrane association or to enhance lipid compatibility. The hyaluronic acid linkers are used for enhanced water retention and viscosity. The succinic acid linkers are used as a spacer that can be easily modified. The cleavable linkers, such as disulfide linkers, are cleavable inside the target cell.

[0140] The peptide linker may be selected from the group comprising or consisting of an amino acid sequence selected from any one of the following: Glycine-Glycine-Glycine (GGG); Glycine-Serine-Glycine (GSG); EAAAK (SEQ ID NO: 143); GSTSG (SEQ ID NO: 144); GGSGG (SEQ ID NO: 145); (Gly4Ser)n(SEQ ID NO: 146); (Ser-Gly)s (SEQ ID NO: 147); K(GGGGS)n (SEQ ID NO: 148); or SGGGG (SEQ ID NO: 149).

[0141] The selected peptide linkers may lead to advantageous molecular structures. GGG provides high flexibility due to the small size and minimal side chain of glycine, which allows free rotation. GSG adds a serine to introduce a hydroxyl group, which can increase hydrophilicity slightly while maintaining flexibility. EAAAK (SEQ ID NO: 143) is a rigid linker that helps in maintaining the structure and orientation of linked domains or peptides. The alanine (A) residue avoids interactions with surrounding structures, while glutamate (E) and lysine (K) at the end provide solubility. GSTSG (SEQ ID NO: 144) includes both glycine (G) and serine (S) residues to balance flexibility and hydrophilicity, which is useful for sensitive applications where structure and solubility are crucial. GGSGG (SEQ ID NO: 145) is similar to GSG, but with additional glycines to enhance flexibility, which is particularly useful in fusion proteins to reduce steric hindrance. (Gly4Ser)n (SEQ ID NO: 146) is a repeat unit of four glycines followed by a serine, used to create a longer, highly flexible and soluble linker. The 'n' can vary to adjust the linker length according to specific needs. (Ser-Gly)s (SEQ ID NO: 147) offers a balance of serine and glycine to provide both flexibility and enhanced solubility, which is useful in recombinant protein production. K(GGGGS)n (SEQ ID NO: 148) is a repeat of glycine-serine with a lysine residue, which is often used to enhance solubility and add potential sites for post-translational modifications. SGGGG (SEQ ID NO: 149) is primarily composed of glycines for maximal flexibility with a serine at one end to increase aqueous solubility.The at least one tag including a tag conjugated to the at least one targeting motif may be a lipophilic tag such as a palmitoyl-motif and / or a heterobifunctional tag conjugated to a further therapeutic or diagnostic agent. For example, the at least one tag may function to enhance tissue penetration, visualization, targeting (including macrophage targeting), cellular uptake and / or incorporation into the delivery system.

[0142] The at least one delivery system may be a carrier or delivery system including various lipid-based systems, selected from the group comprising or consisting of lipid nanoparticles (LNPs), liposomes, or other lipid-like vesicle carriers including nanoemulsions which enhance the transport and stability of the photosensitizers into the target tissues. In a preferred embodiment of the first aspect of the invention, the delivery system may be a targeted delivery system such as a lipid nanoparticle, liposome, nanoemulsion, or other lipid-like vesicle carrier adapted to target one or more cell types, including macrophage cells, cells located in the dermis, hair follicles, a sebaceous gland or a sweat gland. Preferably the delivery system is targeted to macrophage cells located in the dermis, sebaceous gland or sweat gland, or to hair follicles. One possible example of a nanoemulsion delivery system is the PHEROID delivery system (US10363324; Grobler, 2009; Grobler, 2008; and Uys, 2006).

[0143] Alternatively, the delivery system may be formulated as a polymer hydrogel. Further alternatively, the delivery system may be formulated as a patch including a hydrogel patch.

[0144] In one particular embodiment of the first aspect of the invention, the at least one targeting motif is a synthesized aptamer and is conjugated at either the 5’ or 3’ end with at least one linker. In this embodiment, the at least one linker may be selected from the group consisting of a polyethylene glycol (PEG) linker, a glycine-serine (GS) linker, a maleimide linker, a fatty acid linker, a hyaluronic acid linker, a succinic acid linker and / or a cleavable linker, in order to facilitate further functionalization or conjugation with other molecules. In this embodiment, preferably, the at least one linker is a peptide linker having an amino acid sequence comprising any one of the following: Glycine-Glycine-Glycine (GGG); Glycine-Serine-Glycine (GSG); EAAAK(SEQ ID NO: 143); GSTSG (SEQ ID NO: 144); GGSGG (SEQ ID NO: 145); (Gly4Ser)n(SEQ ID NO: 146); (Ser-Gly)5(SEQ ID NO: 147); K(GGGGS)n(SEQ ID NO: 148); or SGGGG (SEQ ID NO: 149).

[0145] In one possible embodiment of the first aspect of the invention, the at least one delivery system may be functionalised with the at least one targeting motif or tag for targeted delivery by the delivery system. For example, a nanoemulsion delivery system may be functionalised with a palmitoyl-motif anchored within its lipid layer. The nanoemulsion delivery system may be formulated with one or more emulsifying agents such as xanthan gum.

[0146] In yet a further possible embodiment of the first aspect of the invention, where the least one photoacoustic compound is a quencher, the quencher may be targeted to a characteristic of a molecule to be targeted, such as the colour of a molecule present in target macrophages in human skin. For example, such coloured molecules may be ink molecules forming a tattoo. In this case, the targeted quencher to be used may be selected based on the colour of the molecules that have been used for the tattoo.

[0147] The targeted delivery system may be formulated as a composition for delivery by transdermal injection, high-pressure jet injection, cream, patch or lotion.

[0148] The at least one cell population may be a macrophage cell population, or a cell population located in the dermis, a hair follicle, a sebaceous gland or a sweat gland. Preferably the at least one cell population is a macrophage cell population located in the dermis, sebaceous gland or sweat gland or is a hair follicle.

[0149] The targeted delivery system may be formulated to include one or more additives or pharmaceutically or cosmetically acceptable excipients including one or more moisturizers such as glycerin (5%) and / or hyaluronic acid (0.5%) to improve skin hydration and comfort during treatment, one or more stabilizers and / or preservatives such as tocopherol acetate (Vitamin E, 1%) and phenoxyethanol (0.5%), one or more synthetic or natural antimicrobial, anti-inflammatory or antioxidant compounds or compositions such as essential oils including aloe vera, or tea tree oil, or one or moreemulsifying agents such as xanthan gum. It is to be appreciated that one or more additional additives or excipients known to those skilled in the art may be included. For example, the one or more additives may comprise one or more chelating agents to bind dispersed metallic ink particles, rendering them water-soluble and facilitating their elimination from the body. In this context, the one or more additives may be selected from deferiprone, or EDTA or another suitable chelating agent suitable for medical use known to those skilled in the art.

[0150] In one preferred embodiment of the first aspect of the invention, the targeted delivery system comprises or consists of:

[0151] at least one targeting motif and at least one tag selected from the group comprising or consisting of at least one nucleotide aptamer, at least one peptide aptamer, or at least one peptide sequence for targeting at least one cell population selected from a cell population located in the dermis or a macrophage cell population, more particularly a macrophage cell population located in the dermis, sebaceous gland or sweat gland, or a hair follicle, particularly of a subject having a fair hair colour or fair skin characterized by low levels of eumelanin, resulting in hair shades that can range from light blonde to light brown;

[0152] the at least one targeting motif being conjugated to at least one linker selected from any one of the following: Glycine-Glycine-Glycine (GGG); Glycine-Serine-Glycine (GSG); EAAAK (SEQ ID NO: 143); GSTSG (SEQ ID NO: 144); GGSGG (SEQ ID NO: 145); (Gly4Ser)n(SEQ ID NO: 146); (Ser-Gly)s (SEQ ID NO: 147); K(GGGGS)n (SEQ ID NO: 148); or SGGGG (SEQ ID NO: 149), more particularly EAAAK (SEQ ID NO: 143);

[0153] at least one chromophore or photoacoustic compound selected from carbon black or a black hole quencher such as BMN-Q651 having an absorption maximum within the optical window of the skin selected from between 500 nm and 1350 nm or any wavelength therebetween, more preferably from between 650 nm and 1270 nm or any wavelength therebetween, or preferably 1064 nm at 1 photon excitation and 532 nm at 2 photon excitation for carbon black, and between 650 nm and 900 nm or any wavelength therebetween, preferably 660 nm, for the black hole quencher, conjugated to the at least one targeting motif by at least one linker; andat least one delivery system selected from a lipid-based system, such as a lipid nanoparticle (LNP), liposome, or other lipid-like vesicle carrier including a nanoemulsion, more preferably a nanoemulsion, functionalised to display the at least one tag on its surface and encapsulating the at least one targeting motif-conjugated chromophore or photoacoustic compound.

[0154] In a second preferred embodiment of the first aspect of the invention, the targeted photoacoustic system comprises:

[0155] at least one targeting motif selected from the group comprising or consisting of at least one nucleotide aptamer, at least one peptide aptamer, or at least one peptide sequence for targeting at least one cell population selected from a cell population located in the dermis or a macrophage cell population, more particularly a macrophage cell population located in the dermis, sebaceous gland or sweat gland, or a hair follicle, particularly of a subject having a fair hair colour or fair skin characterized by low levels of eumelanin, resulting in hair shades that can range from light blonde to light brown;

[0156] the at least one targeting motif being conjugated to at least one linker selected from any one of the following: Glycine-Glycine-Glycine (GGG); Glycine-Serine-Glycine (GSG); EAAAK (SEQ ID NO: 143); GSTSG (SEQ ID NO: 144); GGSGG (SEQ ID NO: 145); (Gly4Ser)n (SEQ ID NO: 146); (Ser-Gly)s (SEQ ID NO: 147); K(GGGGS)n(SEQ ID NO: 148); or SGGGG (SEQ ID NO: 149), more particularly EAAAK (SEQ ID NO: 143);

[0157] at least one tag conjugated to the at least one targeting motif by the at least one linker;

[0158] at least one chromophore or photoacoustic compound selected from carbon black or a black hole quencher such as BMN-Q651 having an absorption maximum within the optical window of the skin selected from between 500 nm and 1350 nm or any wavelength therebetween, more preferably from between 650 nm and 1270 nm or any wavelength therebetween, or preferably 1064 nm at 1 photon excitation and 532 nm at 2 photon excitation for carbon black, and between 650 nm and 900 nm or any wavelength therebetween, preferably 660 nm for the black hole quencher; and

[0159] at least one delivery system selected from a lipid-based system, such as a lipid nanoparticle (LNP), liposome, or other lipid-like vesicle carrier including a nanoemulsion, more preferably a nanoemulsion, functionalised to display the tag-conjugated targeting motif on its surface and encapsulating the chromophore or photoacoustic compound.

[0160] In a third preferred embodiment of the first aspect of the invention, the targeted photoacoustic system comprises:

[0161] at least one targeting motif and / or at least one tag selected from the group comprising or consisting of at least one nucleotide aptamer, at least one peptide aptamer, or at least one peptide sequence for targeting at least one cell population selected from a cell population located in the dermis or a macrophage cell population, more particularly a macrophage cell population located in the dermis, sebaceous gland or sweat gland, or a hair follicle, particularly of a subject having a fair hair colour or fair skin characterized by low levels of eumelanin, resulting in hair shades that can range from light blonde to light brown;

[0162] optionally the at least one tag being conjugated to the at least one targeting motif by at least one linker selected from any one of the following: Glycine-Glycine-Glycine (GGG); Glycine-Serine-Glycine (GSG); EAAAK (SEQ ID NO: 143); GSTSG (SEQ ID NO: 144); GGSGG (SEQ ID NO: 145); (Gly4Ser)n(SEQ ID NO: 146); (Ser-Gly)5(SEQ ID NO: 147); K(GGGGS)n (SEQ ID NO: 148); or SGGGG (SEQ ID NO: 149), more particularly EAAAK (SEQ ID NO: 143);

[0163] at least one chromophore or photoacoustic compound selected from carbon black or a black hole quencher such as BMN-Q651 having an absorption maximum within the optical window of the skin selected from between 500 nm and 1350 nm or any wavelength therebetween, more preferably from between 650 nm and 1270 nm or any wavelength therebetween, or preferably 1064 nm at 1 photon excitation and 532 nm at 2 photon excitation for carbon black, and between 650 nm and 900 nm or any wavelength therebetween, preferably 660 nm for the black hole quencher; and

[0164] at least one delivery system selected from a polymer hydrogel, including a polymer hydrogel formulated as a hydrogel patch comprising the targeting motif, the tag or the tag-conjugated targeting motif and the chromophore or photoacoustic compound.

[0165] In a fourth preferred embodiment of the first aspect of the invention, the targeted delivery system comprises or consists of:at least one targeting motif and / or at least one tag selected from the group comprising or consisting of at least one nucleotide aptamer, at least one peptide aptamer, or at least one peptide sequence for targeting at least one cell population selected from a cell population located in the dermis or a macrophage cell population, more particularly a macrophage cell population located in the dermis, sebaceous gland or sweat gland, or a hair follicle, particularly of a subject having a fair hair colour or fair skin characterized by low levels of eumelanin, resulting in hair shades that can range from light blonde to light brown;

[0166] the at least one targeting motif being conjugated to at least one linker selected from any one of the following: Glycine-Glycine-Glycine (GGG); Glycine-Serine-Glycine (GSG); EAAAK (SEQ ID NO: 143); GSTSG (SEQ ID NO: 144); GGSGG (SEQ ID NO: 145); (Gly4Ser)n(SEQ ID NO: 146); (Ser-Gly)s (SEQ ID NO: 147); K(GGGGS)n(SEQ ID NO: 148); or SGGGG (SEQ ID NO: 149), more particularly EAAAK (SEQ ID NO: 143);

[0167] at least one chromophore or photoacoustic compound selected from carbon black or a black hole quencher such as BMN-Q651 having an absorption maximum within the optical window of the skin selected from between 500 nm and 1350 nm or any wavelength therebetween, more preferably from between 650 nm and 1270 nm or any wavelength therebetween, or preferably 1064 nm at 1 photon excitation and 532 nm at 2 photon excitation for carbon black, and between 650 nm and 900 nm or any wavelength therebetween, preferably 660 nm for a black hole quencher, conjugated to the at least one targeting motif by at least one linker; and

[0168] at least one delivery system selected from a polymer hydrogel, including a polymer hydrogel formulated as a hydrogel patch comprising the at least one targeting motif-conjugated chromophore or photoacoustic compound.

[0169] The at least one targeting motif may be a nucleotide aptamer selected from the group consisting of any one of SEQ ID NOS: 1 -119; a macrophage targeting peptide aptamer selected from the group consisting of any one of SEQ ID NOS: 120-135; a skin penetrating peptide selected from the group consisting of SEQ ID NOs: 136 to 142; or a hair follicle targeting peptide selected from the group consisting of SEQ ID NOs: 150In a preferential embodiment for hair follicle targeting including from a subject having a fair hair colour or fair skin characterized by low levels of eumelanin, resulting in hair shades that can range from light blonde to light brown, the photoacoustic compound is a nanoparticle selected from a gold nanoparticle or a carbon black nanoparticle, most preferably a carbon black nanoparticle. In an alternative preferential embodiment, the photoacoustic compound is for macrophage targeting and is a black hole quencher such as BMN-Q651. The at least one tag may selected from the group comprising or consisting of a macrophage colony stimulating factor (M-CSF); colony-stimulating factor-1; mannose; scavenger receptor A (SR-A); C-type lectin receptor 2 (CLE2); or at least one human antibody or may be a lipophilic tag and / or a heterobifunctional tag. For example, the at least one tag may function to enhance tissue penetration, visualization, targeting (including macrophage targeting), cellular uptake and / or incorporation into the delivery system.

[0170] The at least one targeting motif may be a peptide sequence for hair follicle targeting that is further adapted by conjugation of a skin penetrating peptide tag, thereby to facilitate transdermal transport of the chromatophore or photoacoustic compound.

[0171] The targeted delivery system may be formulated as a composition for delivery by transdermal injection, high-pressure jet injection, cream, patch or lotion.

[0172] According to a second aspect of the invention, there is provided a composition comprising the targeted delivery system of the invention as described above. The composition may be a pharmaceutical or cosmetic composition. The composition may comprise one or more pharmaceutically acceptable additives and / or excipients. For example, the one or more additives may comprise one or more chelating agents to bind the dispersed metallic ink particles, rendering them water-soluble and facilitating their elimination from the body. In this context, the one or more additives may be selected from deferiprone or EDTA or another suitable chelating agent suitable for medical use known to those skilled in the art.According to a third aspect of the invention, there is provided a device for treating one or more skin or hair-associated diseases or conditions and / or for removal of tattoos, the device comprising:

[0173] a reservoir containing the targeted delivery system or composition according to the invention;

[0174] an applicator for applying the targeted delivery system or composition to the skin; an illuminator, for illuminating skin with a specified frequency of light; and optionally a computer comprising a computer program to operate the device.

[0175] The one or more skin-associated disease or condition may be comprised of the group selected from acne, scars, stretch marks, cellulite, hyperhidrosis, removal of skin tags, facilitating skin-tightening, or skin cancer.

[0176] More particularly, the third aspect of the invention is for removal of tattoos or for one or more hair-treatments selected from hair-removal, hair regrowth or hair colouring. In particular, the hair-treatments are for treatment of a subject having a fair hair colour or fair skin characterized by low levels of eumelanin, resulting in hair shades that can range from light blonde to light brown.

[0177] The applicator may be a transdermal injector or high-pressure jet injector.

[0178] The illuminator may be a laser, preferably a pulse laser, more preferably a Q-switched pulse laser. The illuminator may further illuminate the skin for a specified period of time, preferably less than 5 minutes, more preferably less than 1 minute, most preferably less than 20 seconds.

[0179] The specified frequency of light may have a frequency within the optical window of the skin, preferably a frequency selected from between 500 nm and 1350 nm or any wavelength therebetween, more preferably from between 650 nm and 1270 nm or any wavelength therebetween, or preferably 1064 nm at 1 photon excitation and 532 nm at 2 photon excitation for carbon black, and between 650 nm and 900 nm or any wavelength therebetween, preferably 660 nm for a black hole quencher.According to a fourth aspect of the invention, there is provided a kit comprising the targeted delivery system, a pharmaceutical or cosmetic composition comprising the targeted delivery system, or a device according to the invention; one or more reagents; and optionally instructions for use.

[0180] According to a fifth aspect of the invention, there is provided a targeted delivery system, a composition, a device or a kit according to the invention as described above for use in a method of targeting at least one cell population. The at least one cell population may be a macrophage cell population or at least one cell population located in the dermis, a sebaceous gland or a sweat gland. Preferably the at least one cell population is a macrophage cell population located in the dermis, sebaceous gland or sweat gland or is a hair follicle, particularly of a subject having a fair hair colour or fair skin characterized by low levels of eumelanin, resulting in hair shades that can range from light blonde to light brown.

[0181] According to a sixth aspect of the invention, there is provided a targeted delivery system, a composition, a device or a kit according to the invention as described above for use in a method of treatment of a skin or hair-associated disease or condition, for removal of tattoos, or both. The skin-associated disease or condition may be comprised of the group selected from acne, scars, stretch marks, hyperhidrosis, cellulite, removal of skin tags, facilitating skin-tightening, or skin cancer. The tattoo for removal may be a monochromatic tattoo or a multichromatic tattoo. More particularly, the sixth aspect of the invention is for removal of tattoos or for one or more hairtreatments selected from hair-removal, hair regrowth or hair colouring. In particular, the hair-treatments are for treatment of a subject having a fair hair colour or fair skin characterized by low levels of eumelanin, resulting in hair shades that can range from light blonde to light brown.

[0182] According to a seventh aspect of the invention there is provided use of a targeted delivery system according to the invention in the manufacture of a composition or device for use in a method of treatment of a skin or hair-associated disease or condition, for removal of tattoos, or both. The skin-associated disease or condition may be comprised of the group selected from acne, scars, stretch marks, cellulite,hyperhidrosis, removal of skin tags, facilitating skin-tightening, or skin cancer. The tattoo for removal may be a monochromatic tattoo or a multichromatic tattoo. More particularly, the seventh aspect of the invention is for removal of tattoos or for one or more hair-treatments selected from hair-removal, hair regrowth or hair colouring. In particular, the hair-treatments are for treatment of a subject having a fair hair colour or fair skin characterized by low levels of eumelanin, resulting in hair shades that can range from light blonde to light brown.

[0183] According to an eighth aspect of the invention, there is provided a method of preparation of a targeted delivery system according to the invention, the method comprising the steps of:

[0184] i) identifying at least one cell population for targeting;

[0185] ii) providing the at least one chromophore or photoacoustic compound as described above;

[0186] iii) providing the at least one targeting motif and / or the at least one tag as described above for targeting the at least one cell population;

[0187] iv) A. conjugating the at least one targeting motif to the at least one chromophore or photoacoustic compound by at least one linker as described above, or

[0188] B. optionally, where present, conjugating the at least one tag to the at least one targeting motif by at least one linker as described above;

[0189] v) providing a delivery system as described above;

[0190] vi) A. optionally, where present, contacting the at least one targeting motif, at least one tag, or the at least one tag-conjugated targeting motif with the delivery system, thereby to functionalise the delivery system to have the at least one targeting motif, at least one tag or the at least one tag -conjugated targeting motif displayed on its surface, and contacting the functionalised delivery system with the chromophore or photoacoustic compound thereby to encapsulate the chromophore or photoacoustic compound; or B. contacting the delivery system with the targeting motif-conjugated chromophore or photoacoustic compound, thereby to encapsulate the chromophore or photoacoustic compound and display the targeting motif on its surface; orC. contacting the delivery system with the at least one tag, thereby to functionalise the delivery system to have the at least one tag displayed on its surface, and contacting the functionalised delivery system with the targeting motif-conjugated chromophore or photoacoustic compound, thereby to encapsulate the chromophore or photoacoustic compound and display the targeting motif on its surface,

[0191] thereby to form the targeted delivery system.

[0192] The targeted delivery system may be further comprised within a device, or a kit as described above.

[0193] The at least one cell population for targeting may be a cell population located in the dermis, a sebaceous gland or a sweat gland. Preferably the at least one cell population is a macrophage cell population located in the dermis, sebaceous gland or sweat gland. More preferably the at least one cell population is a macrophage cell population located in the dermis, sebaceous gland or sweat gland, or is a hair follicle, particularly of a subject having a fair hair colour or fair skin characterized by low levels of eumelanin, resulting in hair shades that can range from light blonde to light brown.

[0194] In one possible embodiment of the eighth aspect of the invention, the step of targeting motif selection may comprise the selection of appropriate targeting motifs from the group consisting of nucleotide aptamers, peptide aptamers, peptides, antibodies or nanobodies as hereinbefore described.

[0195] The tag may be a skin penetrating peptide tag as hereinbefore described, or a lipophilic tag, including a palmitoyl (PALM) tag or a heterobifunctional tag.

[0196] According to a ninth aspect of the invention, there is provided a computer program for operating a system comprising program code means for causing a computer to carry out a method of targeting at least one cell population with the use of the device according to the third aspect of the invention.The computer which comprises the computer program may for instance form an integrated part of a control unit of the system comprising program code and be implemented as a microcontroller or microprocessor. Alternatively, the computer may form an integrated part of a central unit that is spatially separated from the rest of the system and is configured to control parts of this system and / or a number of further related apparatuses.

[0197] BRIEF DESCRIPTION OF DRAWINGS

[0198] The invention will now be further described, by way of example, with reference to the accompanying diagrammatic drawings.

[0199] In the drawings:

[0200] FIG. 1 shows a graph of the photoacoustic signal intensity over time in Nile Red- labelled macrophages;

[0201] FIG. 2 shows an embodiment of a method 100 for producing aptamers according to the invention;

[0202] FIG. 3 shows an embodiment of a method 200 for targeting specific tissue, in particular for providing a dermatological therapy and / or diagnostic for human skin, according to the invention;

[0203] FIG. 4 shows the effect of the method 200 of the invention on the target macrophages 310 in the human skin 305;

[0204] FIG. 5 shows an embodiment of a system 400 for targeting specific tissue, in particular for providing a dermatological therapy and / or diagnostic for human skin;

[0205] FIG. 6 shows results from an ex vivo, full-thickness skin model in which sub- epidermal macrophages can be seen containing Nile Red as the tattoo dye (A, D and F) prior to inclusion of the quencher formulation (Quencher P= peptide and Quencher A= aptamer as described in Example 9) and in which specific quenching of the Nile Red dye in the macrophages can be seen after inclusion of the quencher formulations (B, C, E and G); and FIG. 7 A1, A2 and B1, B2 show the results of in vivo treatment of skin with the quencher formulation. A1 and B1 are prior to application of the quencherformulation and A2 and B2 are 12 hours after application of the quencher formulation;

[0206] FIG. 8 shows the results of in vivo treatment of skin with the quencher formulation and aptamer targeting system as described in Example 3. A is prior to treatment, B is after the first treatment with the quencher formulation and laser treatment and C is after the second treatment with the quencher formulation and laser treatment; and

[0207] FIG. 9 shows the results of an in vivo treatment of skin with the targeted photoacoustic system as described in Example 12. A is volar forearm skin with blond hair prior to treatment and B is the same skin area after topical application of the system, 10 minutes incubation, and cleaning of the skin surface.

[0208] DETAILED DESCRIPTION

[0209] The following description of example embodiments of the invention are provided as enabling teachings of the invention. Those skilled in the relevant art will recognise that changes can be made to the example embodiments described, while still attaining the beneficial results of the present invention. It will also be apparent that some of the desired benefits of the present invention can be attained by selecting some of the features of the example embodiments without utilising other features. Accordingly, those skilled in the art will recognise that modifications and adaptations to the example embodiments are possible and can even be desirable in certain circumstances and are a part of the present invention. Thus, the following descriptions of the example embodiments are provided as illustrative of the principles of the present invention and not a limitation thereof.

[0210] Example 1 - A targeted photoacoustic system, in this example for tattoo removal

[0211] A targeted photoacoustic system, in this example for tattoo removal, was manufactured using the following steps:

[0212] i) identifying a cell population of macrophages in the dermis comprising tattoo ink compounds for targeting;ii) selecting and synthesising a targeting motif in the form of an aptamer or a skin-penetrating peptide for targeting the population of macrophages; iii) providing a photoacoustic compound having an absorption maximum within the optical window of the skin, preferably an absorption maximum selected from between 500 nm and 1350 nm or any wavelength therebetween, more preferably from between 650 nm and 1270 nm or any wavelength therebetween, or preferably 1064 nm at 1 photon excitation and 532 nm at 2 photon excitation for carbon black, and between 650 nm and 900 nm or any wavelength therebetween, preferably 660 nm for the black hole quencher;

[0213] iv) providing at least one linker as described above, for conjugating the at least one targeting motif to the at least one photoacoustic compound; v) contacting the at least one photoacoustic compound and the at least one linker, thereby to conjugate the at least one targeting motif to the at least one photoacoustic compound;

[0214] vi) optionally providing at least one tag as described above and contacting the at least one tag and the at least one photoacoustic compound or the at least one targeting motif to conjugate the at least one tag to the at least one photoacoustic compound or the at least one targeting motif;

[0215] vii) optionally providing a delivery system as described above and formulating the at least one linker, at least one photoacoustic compound, and at least one targeting motif, and optionally functionalising the delivery system with the at least one tag to form the targeted photoacoustic system.

[0216] The aptamers in this exemplary example were selected with the use of the known “Systematic Evolution of Ligands by Exponential enrichment” (SELEX) process, and the identified nucleotide aptamers resulting from this process are described in SEQ ID NOS: 1 to 119.

[0217] For example, any one or more of the following nucleotide aptamer sequences may be used:

[0218] GAAGAGTAGATATTATGTTTTTACACCCGATAAAAGGCACGTGCGTCCTACC SEQ ID NO: 1 GTAACGGAGATGATATGTTTTTTCCCCCGATAAAAGGGACGGGCGGCATACA SEQ ID NO: 2

[0219]

[0220] TAAGAGTAGATGAAAAGTCTTCTCGCCCGCTAAAAGGGTCGTGCGCCTCGCA SEQ ID NO: 3 AAATCGTCGATGAAACGTTTTTTGGCCCGATAAAGGGGACTCGGGTCAGGCA SEQ ID NO: 4 TAAGAGTAGATGCAACGGTATTTAGCCCGATACAATGGGCGTGCTTCAGATA SEQ ID NO: 5 AAACACTAGATTAATCGTTTTTTCGGCCGCTAAAAGTGATGTGCGTCAGACT SEQ ID NO: 6 GAAGTTTACACGAAACCTTTGTTCGCCAGATAGAAGGCACGTGCGACAGACA SEQ ID NO: 7 GAAGAGTCGATGTAACGTTTTTTCGCACGATAATAGGGACGTGAGTCAGACA SEQ ID NO: 8 GAAGAGTATAAGACCCGTTTTGTCGTCGGATAGAAGGGACATGCGTAAGACA SEQ ID NO: 9 GAAGCGTAGATGAAACGTTTTTTCGTACGATATAAGGTAACGGCGTCCTACA SEQ ID NO: 10 GAAGAGAAGATGAAACGTTCTCTCGTCCGAAATCAGGGACGTGCATTTGACA SEQ ID NO: 11 GTAGATTAGATGAAACGTTTTTTAGCCTGATAAAAAGGGTGTGCATGAGTCA SEQ ID NO: 12 AAAGAGTTGCTGAGACGTTTTTTCGACCTGTAAAAGTGACGTGCGCCAGCCA SEQ ID NO: 13 GAAAAGTTGTTGAAACCTTATTTCGCACGATAAAAGGGTCTAGCGTCAGCCA SEQ ID NO: 14 GAAGACAAAATGCAACGTTTTAGCGCCCGATGAAAGCGACGTGCGTCAGATG SEQ ID NO: 15 GAGGTGTAGAAGAAACGTTTTTTCGCCTGTTCAAAGTCACGGGCGTTAGACA SEQ ID NO: 16 GTAGAGTAGATGAAACTTTTTTCAGTCCGATGAAAGGGACGAGCGTTAGTCC SEQ ID NO: 17 GAAGTGGGGATGCAACATTTTTTCGCCCGATAAAAGAGACGTGACACATACA SEQ ID NO: 18 GAAGAGAAGATGAAACGTCGTTTCACCCGGTAAAAGGGAGTTGAGTTTGACA SEQ ID NO: 19 CAAGAAGCGATGAAACGAATTTTCGCCTGATAAAAGAGACGTGCGTGAGAAA SEQ ID NO: 20 GAAAAGTAGATGACACGTTCTTGCGCCCTATAATAGGGACGGGGGGTAGACA SEQ ID NO: 21 GACCAGTACATAAAACGTTTTTTGGCCCGATAGAGGGGACGTGCGTTATAAA SEQ ID NO: 22 GATGATCAGATAAAACGTTTTTTCACCCGGTGAAACGGACGTGCGTCGGGCA SEQ ID NO: 23 GAAGAGTTGTGGTATCGTTTTTCCGCCCGAGAAAAGGGATGTACGTCAGACT SEQ ID NO: 24 GAAGCGTGAATTAAGCGTCTTTTCGCCCGCTAAAAGGGTAGTGCGTCAGTCA SEQ ID NO: 25 GAAGCGTAGAGGAAACGTTTTTAGGGACGCTAAAAGGGCCGAGCGACAGACA SEQ ID NO: 26 GAAGAGCAGATTCAACGTTTTTTCGTTCGATAAAAGCAGCATGCGACAGACA SEQ ID NO: 27 GGAGAGGGGGTGAAACGTTTATTCGTCTGATTAAAGAGACGTGCGTCAAACA SEQ ID NO: 28 GAAGCGAAGAGGTAACGTTTTTACGCGCGATAAAACGGACGTGCGTGTTACA SEQ ID NO: 29 GAAGATTAGATGAAACGTATTGTCGCCCGATAACAGGAACGTGCATGCGGGA SEQ ID NO: 30 GAAAAGTAGATGAAACCTTTCTTCTCGCGATAAAAGGGGCGTGCGACCAAGA SEQ ID NO: 31 GAGAAGTAAATGAAACGGTTATTCGTCCGATGAAAGGGACGGGCGTCAGTCG SEQ ID NO: 32 GAAGAGTTGATGAAACGTTGTATTCACCGAGACAAGGGGCGTGCGTCGGACA SEQ ID NO: 33 GACGAGTAGATGTAACTTTTCTTCGCCCGATACTCGGGACGGGCGTCGGAAA SEQ ID NO: 34 GATTATTAGACCACACGTTTTTTCGCCCGATAAAAGAGACGCGCGTTAGACG SEQ ID NO: 35 GCAGAGTAGATGAAACGTTTTATCGGCTTAAAAACGGGACGTGGGGCAGAGA SEQ ID NO: 36 CTTCTTATCTACTTTGCATAAAAGTGGGCCTGTTTGCCCTTCACGCGGTCTGT SEQ ID NO: 37 CTTCTCCTCTGCTTTGCAAAATAGCAGGCCTGTATTCCTTGCGCGCAGTCTCT SEQ ID NO: 38 CTTCTCAGCTGCTTTGCATAAAATCCGGGTCTGTCTCCCTACACGCAGTCAGT SEQ ID NO: 39

[0221]

[0222] CTTCTCCTCTGCTTTGCATGAAAGCGTGGCTCTGTTCCCGTGCACGCAGTCTGC SEQ ID NO: 40 CTTCTCCTCTACTTTGCGTAAAAGCGGGCTGTTTTCCTTGCACGTAGTCTGCGT SEQ ID NO: 41 CTTCTCTTCTCCTTTGCAAAGAAGCGCGGCTGTTTTCCTCGCACGCGGTGTGCT SEQ ID NO: 42 CTTCTCATCTGCTTTGCATAAAAACGAGGCATATTTCCCTTCACTGCAGTCAGC SEQ ID NO: 43 CTTCTCATCTACTTTGCATAATAAGTGGGCTGTTTTCCCTGCACGCCGTGTGCT SEQ ID NO: 44 CTTCTCATCTGCTTTGCATAAAAAGCGGGCTATTTTCCCTTCTTCGAGTCTCTG SEQ ID NO: 45 CTTCTCATCTACTTTGCAAATAAAGCAGGCTTTTTTCCTTGCACGCAGTCTGTT SEQ ID NO: 46 CTTCTCATCGACTTTGCATAAAAGCGAGGCTATTTTCCCTGCACTCAGTCTCTG SEQ ID NO: 47 CTTCTCGTCTACTTTGCAATAAAGCGGGCTCTTTTCCCTGCACGCAGTCGTTGT SEQ ID NO: 48 CTTCTCATCTACTTTGCAAATAAGCGGGCTATTTTCCCTGCACGCTGTCTGTAT SEQ ID NO: 49 CTTCTCATCTACTTTGCATAAAATCGGGCCTATTTTCCCTGCACGCAGTCTGTA SEQ ID NO: 50 CTTCTCCTCTACTTTGCAAAAAGGCGAGCCTATTTTCCCTGCACGCAGTCTGCG SEQ ID NO: 51 CTTCTCATCTACTTTGCATAAAAGTGGGCCTTTTTCCCTGCACGCAGTCAGTGT SEQ ID NO: 52 CTTCTCATCTGCTTTGCAATAAAGCGGGCTATTTTCCCTGCACGCAGTCTGTGT SEQ ID NO: 53 CTTCTCGTCTACTTTGCAAAAAAGCAGGCCTCTTTTCCCTGCACGCAGTCTCTC SEQ ID NO: 54 CTTCTCATCTACTTTGCAGAAAAGCGGGCCGATTTTCCCTGCACGCAGTCTGTG SEQ ID NO: 55 CTTCTCCTCTACTTTGCATAAAAGTGGGCCTGTTTTCCCTGCACGCAGTCAGTG SEQ ID NO: 56 CTTCTCATCTACTTTGCGAAAAAGTGGGCCTATTTTCCCTGCACGCAGTCTGTG SEQ ID NO: 57 CTTCTCATCTACTTTGCAAAAATGCGGGCCTATTTTCCCTGCACGCAGTCTGTC SEQ ID NO: 58 CTTCTCCTCTACTTTGCAAAAAGCGTGGCTGTTTTCCCTGCACGCAGTCTCTGA SEQ ID NO: 59 CTTCTCCTCTACTTTGCAAATAAGCGGGCCGATTTTCCCTGCACGCAGTCAGTG SEQ ID NO: 60 CTTCTCATCTGCTTTGCATAAAAGCGGGCTTTTTTCCCTGCACGCAGTCTGTGA SEQ ID NO: 61 CTTCTCATCTACTTTGCATAAAAAGCGGGCTATTTTCCCTGCACGCAGTCTGCT SEQ ID NO: 62 CTTCTCATCTACTTTGCAAAAAAGCGGGCCATTTTCCCTGCACGCAGTCTCTGT SEQ ID NO: 63 CTTCTCATCTACTTTGCAATAAAGCGGGCTATTTTCCCTGCACGCAGTCTGTGT SEQ ID NO: 64 CTTCTCATCTACTTTGCAAAAAGCGGGCTATTTTCCCTGCACGCAGTCTGTCT SEQ ID NO: 65 CTTCTCATCTACTTTGCATAAAAAGCGGGCTATTTTCCCTGCACGCAGTCTGTT SEQ ID NO: 66 CTTCTCATCTACTTTGCAAAAAAGCGGGCTATTTTCCCTGCACGCAGTCTGTGT SEQ ID NO: 67 CTTCTCATCTACTTTGCAAAAAAGCGGGCTATTTTCCCTGCACGCAGTCTGTGC SEQ ID NO: 68 GAAAATTAGAGGAAACGTTGTCTCTCCCGATAAAAGAGCCATGCGTTAGACA SEQ ID NO: 69 GAATAGTATATTAAACGTTATTTCACCAGATAAAAGGGCCGTTCGTTAGTCA SEQ ID NO: 70 GAATATTTGATGAAACGTTTTTTCGCCTGATGAAAAGGTTTTCCGTCAGACA SEQ ID NO: 71 AGAGAGTAGATGAAATGTTTTCTCGATCGATAAAGGGTGCGTGCATCAGACA SEQ ID NO: 72 GAAGAAGAGATGATACGTTTTTGGGCCCTATATGAGGGACGTGCGTCACAGA SEQ ID NO: 73 CACAACTAGATGAAACGTTCTTTCGCCCGATCCAAGGGAAATGGGTCAGACA SEQ ID NO: 74 GAAGAGTGGACGAAACATTTTTTGGCCCGACAAAGGGGACCTGCGCCCGATA SEQ ID NO: 75 GAAGAGTATATGCAAGGTTTTTCCGCCCGAGAATACGGACGTCCGTCTAACA SEQ ID NO: 76

[0223]

[0224] GAAGATTAGATGAAACGTTTTATTGTCTGACAAAATGGCAGTGAGTCAGACA SEQ ID NO: 77 GGAGAGCCGATGAAACATTTTTACACCCGGGTAGAGGGACGTGCGTCAGACA SEQ ID NO: 78 GAAGAGTAGATGAAACGTTTTTTCGCCCGATAAAAGGGACGTGCGTCAGACA SEQ ID NO: 79 GCTGAGCATATGAAACGTTATTTCGCCTGTTAGACGGGACGTGCGTCAGACT SEQ ID NO: 80 TAAAAGTAGATGAAACGTCTTTTCGACCGTTTAGAGGGACGAGCCCCAGACA SEQ ID NO: 81 GAAGAGTAGATGCAAGGTTCGTCCACCCGATCAACGGGACATGCGTCCGACA SEQ ID NO: 82 GAAGAATAGGTGTAACGTTCTTTCTCCAGATAAACGGGACGTGAGTCATACT SEQ ID NO: 83 GAACAGCTGTTGACACGTTCTTTCGCGGGACAAAAGGGACGAGCGTCAGACA SEQ ID NO: 84 GAAGAGTAGCTAAAACGATTTCTCGCGTGATAGAAGGAACGGGCGTGAGACA SEQ ID NO: 85 GACGATTGGATGTAACGTGTTCTCGCCCGATAAGCGGGATTTGCGTCAGACA SEQ ID NO: 86 GAAGAGTAGATGATCAGTTCTCTCGCCCGCTACAAGGGAAGGGCGTCAGACG SEQ ID NO: 87 GAGGTGTAATGGAAACGTCTTTTCGCCCTCTAAAAGGGACGTTCGTCTGACA SEQ ID NO: 88 TCTGCCTATATGAAACGTTTATTCGCCCGATAAAAGGTACATTCGTCAGACA SEQ ID NO: 89 GAAGATTAGCTGAAACGTTTTTTCGCTCGATGAAAGGTAACTACGTCATCCA SEQ ID NO: 90 GACGAGTAGATGAAAGGTTCTTTCGCCCGAACAAAGAGACCTGCTTGCGACA SEQ ID NO: 91 GATGATAAGATGAAACGTTTTTCTGTCCGATAAATGCGACGGGCGTCAGACT SEQ ID NO: 92 GAAGAGTAGATGAACCGTTGTCGCGCCTGATCATAAGGACGTGCGTCCTACA SEQ ID NO: 93 TACGAGTACATGATACTTTTTTACGCCCGATACATTGGTCGTGCGTCAGACA SEQ ID NO: 94 CTAGAGAAGAGGAAACTTTTTTTCGCCGGATAAAAGGTGCGTTCGTCTGACA SEQ ID NO: 95 GAAGAGTAAATGAGACGGTTTATCGACTGTGAAAAGGGAAGTGCGTTAGACA SEQ ID NO: 96 GAAGAGTGGATGAAACGCTTTGTCGCCAGGTAAATGGGACGGGCGTCTGCAA SEQ ID NO: 97 GAAGAGTAGATGAAACTTCTTTTCTCCCTATAAAATGGACGTTCTCTAGACG SEQ ID NO: 98 CGACTGATTTACGGGGCTCGTTGATGACGATCAGTCTTAACAGGCTTCCGGAC SEQ ID NO: 99 TTACCGGTTTTCTGGGCGCGTATATGGCTGGCAGTCCTAACATCGTGTAGGAC SEQ ID NO: 100 TGACTGCTTTACGAGGCGGGTAGATGACGTATAGGTCTAACATCCTTTCGGAC SEQ ID NO: 101 TGTCTAATTGAAGGGGCGCGTAGCTGATGAGCAGTCCGAACAGCGTTTAGGAC SEQ ID NO: 102 TGTCTGATTCGGCGGGCGCTTAGCTGATGAGCAGTCCGAACAGCGTTTAGGAC SEQ ID NO: 103 TGACTGATTTACGGGGCGCGTAGATGACGAGTGGTCCTAACATCGCTTAGGAC SEQ ID NO: 104 TGACTGATTTACGGGACGCGTAGATGATGAGCAGTCCTAAGATCGTTTAGGAC SEQ ID NO: 105 TGACTGATTTACGGGGTGCGTAGATGACGAGCAGTCCTAACGTCGTTTAGGAC SEQ ID NO: 106 TGACTGATTTACGGGGCGCATAGATGACGAGCAGTCCTAAGATCGTTTAGGAC SEQ ID NO: 107 ACTGGGGCACCCCATTATGGGTCTCTTTAAGCGGCACGATACCCTTTCGGGAC SEQ ID NO: 108 TGTGCCCCGTCGGGGGGGACCTCCTGCATTCGCAGATACAAACTCTTGCGCCC SEQ ID NO: 109 TGAGAGGTTCATAACTTAAGGCTATAGGCGTCAAGGGAGAATGCGAGAGAGTG SEQ ID NO: 110 GGCCCCTATCCTGCGGCCCAAAAGAACAAACTAAAAGCAGGGAATCTTAACAA SEQ ID NO: 111 ATCTTTAGATTTACAGAAACTGACGGATGTGAGCGACGAAGTCAAATTAATAT SEQ ID NO: 112 GACGAGGTCGTCATCGCGATAATAGCCTTGCAGGATCTGCGTTGTTCAAGCTC SEQ ID NO: 113

[0225]

[0226] GCCTTTTACAATGAACCAGCTGAGAGGTTGCAGTCCCTAAAAACCTTCTGAGA SEQ ID NO: 114 TGCACTACCTGCAGAGGATAATCATGTGGCACGTGCTCAAGCGGAGACATCGA SEQ ID NO: 115 ATTCCCTCAATGTATCCGCCTTGTGGCTGCACCCTCGAATCCAACGTGAGCTA SEQ ID NO: 116 GCCGTCCTTCCACATGGTGCTAGACTGGGTTCCTCTCGGCTATCCATGACATT SEQ ID NO: 117 TGACTGATTTACGGGGCGCGTAGATGACGAGCAGTCCTAACATCGTTTAGGAC SEQ ID NO: 118 CTTCTCATCTACTTTGCAAAAAAGCGGGCTATTTTCCCTGCACGCAGTCTGT SEQ ID NO: 119

[0227]

[0228] The skin-penetrating peptide in this exemplary example comprises or consists of an amino acid sequence of any one of SEQ ID NOS: 136-142.

[0229] The photoacoustic compound in this exemplary example is a Black Hole Quencher-1 (BHQ-1) and is conjugated to the nucleotide aptamer by means of a linker, in this case the conjugation of a peptide linker having an amino acid sequence selected from any one of the following: Glycine-Glycine-Glycine (GGG); Glycine-Serine-Glycine (GSG); EAAAK (SEQ ID NO: 143); GSTSG (SEQ ID NO: 144); GGSGG (SEQ ID NO: 145); (Gly4Ser)n (SEQ ID NO: 146); (Ser-Gly)5(SEQ ID NO: 147); K(GGGGS)n (SEQ ID NO: 148); or SGGGG (SEQ ID NO: 149).

[0230] Example 2 - Manufacture and Experimental Validation of a Targeted Photoacoustic System for Tattoo Removal

[0231] Objective: To develop and validate a targeted photoacoustic system designed for selective targeting of Nile Red-labeled macrophages, using both secondary macrophages derived from a cell line and primary macrophages from donor skin, to enhance tattoo removal applications.

[0232] Materials and Methods:

[0233] 1. Macrophage Preparation and Activation:

[0234] A. Secondary Macrophages Derived from Cell Line (THP-1) Using PMA:

[0235] • Differentiation: THP-1 monocytes were plated in 6-well plates at a density of 1x106cells per well in RPMI-1640 medium with 10% FBS. PMA was added at a concentration of 50 ng / mL to induce differentiation intomacrophage-like cells. Cells were incubated with PMA for 48 hours at 37°C with 5% CO2.

[0236] • Resting Phase: After 48 hours, PMA-containing medium was removed, and cells were cultured in fresh RPMI-1640 with 10% FBS for 24 hours to stabilize the macrophage-like phenotype.

[0237] • Morphological Confirmation: Cells displayed adherence and morphological changes consistent with macrophage differentiation, as observed under microscopy.

[0238] B. Primary Macrophages from Donor Skin Using LPS and IFN-y:

[0239] • Isolation: Primary macrophages were isolated from human skin samples by enzymatic dissociation using collagenase IV (1 mg / mL) at 37°C for 2 hours. CD68 antibody-conjugated magnetic beads were then used to isolate macrophages, achieving a purity of >95%.

[0240] • Activation: Isolated macrophages were plated in 6-well plates at a density of 1x106cells per well and incubated for 24 hours. Activation was induced by adding LPS (10 ng / mL) and IFN-y (20 ng / mL) for an additional 24 hours at 37°C.

[0241] • Confirmation of Activation: Flow cytometry and ELISA confirmed upregulation of surface markers (CD80 / CD86) and increased secretion of pro-inflammatory cytokines (IL-6, TNF-a), characteristic of M1 macrophage activation.

[0242] 2. Tattooing of Macrophages with Nile Red:

[0243] • Following activation, both THP-1-derived macrophages and primary macrophages were incubated with Nile Red (5 pg / mL) for 24 hours to simulate tattoo ink uptake. Nile Red-labeled macrophages appeared red under fluorescence microscopy, indicating successful staining.

[0244] 3. Design and Selection of Targeting Motifs:

[0245] • Aptamer Selection via SELEX: SELEX was conducted to identify aptamers with high affinity to Fey receptors on activated macrophages. Through eight selection cycles, aptamers with dissociation constants around 10 nM were selected for optimal binding specificity.• Peptide Selection via Phage Display and Bioinformatics:

[0246] • Fey receptor binding sites were modeled computationally, and a peptide library was generated to complement these sites. Phage display rounds enriched peptides with a Kd ~15 nM for high-affinity binding.

[0247] 4. Provision and Characterization of the Photoacoustic Compound:

[0248] • Quencher Selection: A photoacoustic quencher with a 680 nm absorption maximum was selected to optimize photoacoustic imaging within the skin’s optical window. Stability was confirmed via HPLC, showing less than 3% degradation over 24 hours.

[0249] 5. Linker Conjugation:

[0250] • Synthesis and Conjugation: An EAAAK (SEQ ID NO: 143) peptide linker was conjugated between the aptamer and quencher using EDC / NHS chemistry, yielding a conjugation efficiency of 90% as verified by MALDI- TOF mass spectrometry.

[0251] • Conjugate Stability: The aptamer- linker-quencher construct was incubated in simulated interstitial fluid, showing minimal degradation (less than 5%) over 48 hours.

[0252] 6. In Vitro Binding, Targeting Validation, and Blackout Experiment:

[0253] • Incubation with Nile Red-Labeled Macrophages and Quencher Application:

[0254] Nile Red-labeled macrophages were incubated with the targeted photoacoustic system at a concentration of 50 pM. Incubation periods were set at 5, 15, 30, and 60 minutes to observe the quencher’s effects over time.

[0255] • Microscopy Readout and Blackout Observation: Fluorescence microscopy served as the primary readout (results not shown). Macrophages labeled with Nile Red initially fluoresced red. Within 10 minutes of exposure to the targeted quencher, a blackout effect was observed, as the quencher absorbed the fluorescence signal, rendering the macrophages dark. The effect was maintained with increasing incubation times, confirming the binding and functional activity of the quencher within the macrophages.7. Ex Vivo Application and Photoacoustic Signal Detection:

[0256] • Formulation in Hydrogel Matrix: The photoacoustic system was incorporated into a hydrogel delivery matrix and applied to ex vivo skin samples.

[0257] • Photoacoustic Signal Measurement: Following laser exposure at 660 nm, a significant photoacoustic signal increase (5.3 mV) was observed in labeled macrophage regions compared to controls (0.4 mV), indicating successful targeting.

[0258] Results:

[0259] The fluorescence microscopy readout revealed the blackout effect upon incubation with the targeted quencher, validating its binding to Nile Red-labeled macrophages. The photoacoustic system demonstrated high specificity and stable signal modulation, supporting its potential for tattoo removal applications. Results showing the photoacoustic signal intensity over time are provided in Figure 1.

[0260] Example 3 - treatment of a skin -associated condition using a targeted photoacoustic system

[0261] In this example, tattoo removal in an ex vivo skin model as previously described (htt s: / / onHneHbrarv.whev.eom / doi / 10.1111 / imm, 13714) was achieved by applying a topical PHEROID formulation containing encapsulated Black Hole like Quencher molecule BMN-Q651

[0262]

[0263] The PHEROID drug delivery system is a unique colloidal drug delivery system and represents a significant advancement in pharmacology, enhancing the bioavailability and therapeutic effectiveness of encapsulated agents. This proprietary formulation employs an innovative approach, utilizing lipid-based carriers to facilitate the efficient transport of compounds through biological membranes including skin (US10363324; Grobler, 2009; Grobler, 2008; and Uys, 2006). By creating a stable microencapsulated environment, the PHEROID system not only enhances the solubility of hydrophobicsubstances but also allows for controlled release and targeted delivery to specific tissues.

[0264] Here PHEROID vesicles were functionalized with a Palm-Tag motif anchored within their lipid layer, presenting a targeting sequence (homing sequence conjugated to a cell penetrating sequence) as either an aptamer or peptide derived from the sequences ID NOs 1 to 149. These targeting and cell-penetrating motifs specifically bind to receptors on tattoo pigment-laden dermal macrophages, enabling selective but passive uptake of the encapsulated quencher.

[0265] Black ink (Sailor Jerry Magic Black 22 991-010, Lot: D14382) was used to tattoo the ex vivo skin model (which is a co-culture with fibroblasts, macrophages and keratinocytes). Thereafter, the encapsulated quencher delivery system was topically applied to the skin surface after cleaning with an alcoholic swap. Laser irradiation was then applied from picolaser (PICOPLUS® of Lutronic) at 660 nm with a fluence of 0.1 J / cm2(about 10 times lower as the standard starting fluence) close to the quencher’s absorption maximum (650 nm), to induce precise photoacoustic lysis of the target macrophages. Three passes over the full tattoo were performed. Non-irradiated skin samples were used as a control for targeted delivery of quencher and show under a fluorescence microscope uptake of the quencher as a blackout effect (as described above) in the absorbance range of the quencher.

[0266] In comparison to the control groups (empty PHEROID system and no topical pretreatment) the quencher groups with aptamer targeting and with peptide targeting led to a full removal of the color from the macrophages and rupture of the macrophages without histologically visible collateral damage. The control groups without quencher also showed no tissue damage at such a low fluence but also no effect of removal of the ink from the macrophages.

[0267] In all samples there was no sign of skin whitening through plasma generation.

[0268] Formulation for the exampleThe delivery formulation in this example is a nanoemulsion based on the PHEROID delivery system optimized for deep skin penetration and macrophage targeting. The desired properties of PHEROID were determined quantitatively (by zeta-potential and particle size distribution) as well as qualitatively (by confocal microscopy). Qualitative characteristics are the forming of vesicles with visible internal structure. Quantitative properties are dependent on the formulation in question.

[0269] Quencher and targeting motif were incorporated by mixing of the quencher and the targeting motif into a Pro-PHEROID solution under continuous stirring for 30 min. After a de-gassing phase the formulation was filled into glass vials and stored at 4 °C until usage.

[0270] Entrapment was demonstrated by a change from the basic formulation particle size distribution (in this case the carrier-control PHEROID MA) upon the incorporation of the quencher and the targeting motif (i.e. the test formulation). This causes an increase in particle size due to the incorporation of the quencher and displaying of the targeting motif on the surface of the vesicles. Furthermore, changes in zeta-potential were observed, with optimal zeta-potential measurements of more than -25 mV (Kleynhans et al., 2019; Roland etal., 2003).

[0271] Initially formulation experiments were conducted to determine which oil: H₂O dilution factor, i.e. 1:2, 1:3 or 1: 5, would provide the best characteristics for the formulation group; the same dilution factor was then to be used in the carrier control group during the ex vivo skin study. The zeta potential, particle size, morphology and the consistency of each formulation were determined and taken into account. The 1:5 (oil: H₂O) formulation formed the optimal PHEROID vesicles, with a particle size span of 43.381 pm and a median particle size of 0.252 pm in the control formulation. The distribution indicated that 80% of the particles were distributed between 0.093 pm and 15.896 pm. The zeta potential was -17.0 ± 3.57 mV.

[0272] In the test formulation, although the quencher did not fully dissolve, the consistency was such that the formulation could be passed through a 22-gage oral gavage needle.The 1:5 (oil: H₂O) control formulation formed optimal PHEROID vesicles with a particle size of the test formulation having a span of 30.868 pm and a median particle size of 0.233 pm. The distribution indicated that 80% of the particles were distributed between 0.098 pm and 14.760 pm The zeta potential was -27.0 ± 6.29 mV.

[0273] The test formulation contains:

[0274] Palm-Tagged PHEROID Vesicles with Targeting and Cell-penetrating Aptamers / Peptide: 12% - Phospholipid-based PHEROID vesicles, functionalized with a Palm-Tag motif anchored within the lipid phase, present an aptamer or peptide targeting sequence selected from any one of SEQ ID NOs 1 to 45 on the surface. These sequences enable binding to receptors on tattoo pigment-laden macrophages, facilitating targeted uptake of the photoacoustic agent.

[0275] Encapsulated Black Hole Quencher BMN-Q651

[0276]

[0277] g-de), Quenching range (550-720nm): 3% - with an absorption maximum at 650 nm, encapsulated within PHEROID vesicles to maintain stability and ensure delivery directly to dermal macrophages.

[0278] Moisturizers: Glycerin (5%) and hyaluronic acid (0.5%) - improve skin hydration and comfort during treatment.

[0279] Stabilizers and Preservatives: Tocopherol acetate (Vitamin E, 1%) and phenoxyethanol (0.5%) - stabilize active components and preserve the formulation. This formulation was provided in glass vials.

[0280] Application Protocol for ex vivo and in vivo skin

[0281] 1. Preparation: Clean the tattooed area thoroughly to remove any surface impurities and facilitate effective skin penetration of the formulation. 2. Application: Apply a thin layer of the Palm-Tagged PHEROID liquid over the tattooed skin. Gently massage to promote initial skin absorption and facilitate dermal penetration. Optionally cover with a plastic film to increase penetration.3. Absorption Time: Allow the formulation to remain on the skin for 30-40 minutes, giving the Palm-Tagged PHEROID vesicles time to penetrate and bind specifically to tattoo pigment-laden macrophages. The targeted macrophages internalize the vesicles, enabling controlled release of the Quencher.

[0282] 4. Laser Treatment: Clean the skin with an alcoholic swab, use a standard Q-switched or better picosecond laser at 660 nm, close to the absorption maximum of the quencher. Set the fluence to 0,1 J / cm2, optimizing energy absorption within macrophages and minimizing tissue damage. Total irradiation time per session is limited to 15 seconds to minimize skin heating and reduce off-target effects.

[0283] 5. Post-Treatment Care: After laser treatment, clean skin again, and apply a soothing cream with e.g. panthenol and allantoin to reduce transient redness or irritation, consider a dressing, re-visit the treatment site frequently and decide when the next treatment cycle might be performed.

[0284] Mechanism of Action

[0285] Upon laser irradiation at 660 nm, the encapsulated quencher within the macrophage-targeted Palm-Tagged PHEROID vesicles absorbs energy, generating localized acoustic waves. This photoacoustic effect selectively lyses pigment-laden macrophages, fragmenting the tattoo ink particles for clearance via the lymphatic system. The 660 nm wavelength is chosen as it is close to the used quenchers absorption peak (650 nm), ensuring effective photoacoustic action within the targeted macrophages, while minimizing off-target tissue damage. Wavelength doubling may also be used, particularly since 1064 nm is a very common laser source with a deep tissue penetration and relatively limited off target effects.

[0286] Results

[0287] In preclinical studies, this Palm-Tagged PHEROID-based test formulation photoacoustic system demonstrated tattoo ink reduction of up to 75% after three sessions, spaced two weeks apart. The Palm-Tag motif on the PHEROID vesiclesenabled high specificity in targeting the encapsulated quencher to pigment-laden macrophages, reducing the risk of scarring or hypopigmentation. Histological analysis confirmed selective lysis of tattoo-pigmented macrophages, preserving surrounding dermal structures and allowing faster recovery times.

[0288] This approach offers a highly effective, minimally invasive tattoo removal option, combining targeted delivery of quencher via Palm-Tagged PHEROID vesicles with precise photoacoustic treatment. The method significantly minimizes patient discomfort and skin damage compared to conventional tattoo removal methods.

[0289] Example 4 - Jet injector delivery

[0290] In this example, the photoacoustic system of Example 1 or 2 (either formulated in a PHEROID delivery system or without such formulation) is provided to a high-pressure jet injector which is used to deliver the photoacoustic system to the target macrophages located in the dermis. Once injected into the dermis, the photoacoustic compound binds to the target macrophages. The region of skin targeted with the photoacoustic system is then treated with a Q-switched pulse laser with a frequency of between 650 nm and 900 nm, with the laser being applied for less than 20 seconds. The resultant photoacoustic effect causes lysis of the target macrophages, while minimizing off-target effects such as whitening or scarring. With less damage to the skin, treatments can be applied rapidly in quick succession to deplete macrophage populations and allow the ink contained in their vesicles to make its way to the lymphatic system.

[0291] Example 5

[0292] Fig. 2 shows a possible embodiment of a method 100 for producing aptamers according to the invention.

[0293] The method 100 is configured for producing aptamers that can be used for selectively modulating target macrophages in a human skin including in the dermis or in a sweat gland or a sebaceous gland. The method 100 comprises the following steps.

[0294] A first step 110 comprises a provision of a probe of the target macrophages that are aimed to be modulated.A next step 120 comprises a synthesizing of aptamers, in particular RNA- and / or DNA-aptamers, by using the “Systematic Evolution of Ligands by Exponential enrichment” (SELEX) process for the provided target macrophages.

[0295] A following step 130 comprises a modification of the synthesized aptamers by applying a quencher, in particular a targeted quencher, to the aptamers in order to adapt optical characteristics of the respective modified aptamers.

[0296] The steps 110, 120 and 130 are preferably provided in the given sequence.

[0297] Preferably, the method comprises further steps.

[0298] A further step can be formed by an identification of the synthesized aptamers before performing step 130. The identification can be performed automatically in order to shorten the time needed to perform the steps of this method.

[0299] Additionally or alternatively, the method can further comprise a conjugation of the synthesized aptamers with at least one linker, in particular a polyethylene glycol linker, a glycine-serine linker, a maleimide linker, a fatty acid linker, a hyaluronic acid linker, a succinic acid linker and / or a cleavable linker, in order to facilitate further functionalization or conjugation with other molecules. Further examples of linkers, in particular of peptide linkers, are given above in the summary of the invention.

[0300] Additionally or alternatively, the method can further comprise an attachment of at least one tag, in particular a lipophilic tag and / or a heterobifunctional tag, in order to enhance tissue penetration, visualization, targeting, cellular uptake and / or an incorporation in carrier like nano-emulsions for the respectively modified aptamers.

[0301] Additionally or alternatively, the method can further comprise an attachment of at least one specific peptide sequence in order to facilitate transdermal delivery. Examples for such peptide sequences are given above in the summary of the invention.Preferably, the modified aptamers are combined with at least one specific peptide sequence and at least one tag and at least one linker, in particular at least one peptide linker. Such a combination can combine an improved transdermal delivery of the aptamers with other advantageous characteristics, such as an improved hydrophilicity or an improved flexibility. The step of attaching further chemical components can be performed prior to step 130 or after step 130 or during step 130.

[0302] In a further variant of said embodiment, the quencher, in particular the targeted quencher, that is applied during step 130, depends on a characteristic of particles, in particular on a color of particles, that are present in the target macrophages in the human skin.

[0303] Example 6

[0304] Fig. 3 shows a possible embodiment of a method 200 for targeting specific tissue, in particular for providing a dermatological therapy and / or diagnostic for human skin including the dermis, a sweat gland or a sebaceous gland, according to the invention.

[0305] The method 200 comprises the following steps.

[0306] A first step 210 comprises a provision of modified aptamers for the target macrophages in the human skin including the dermis, a sweat gland or a sebaceous gland according to the invention.

[0307] A next step 220 comprises an application of the modified aptamers to the target macrophages.

[0308] A final step 230 comprises a radiation of laser light to the target macrophages in the human skin including the dermis, a sweat gland or a sebaceous gland, wherein a wavelength of the laser light depends on the targeted quencher applied to the synthesized aptamers in order to enable specific tissue destruction through the photoacoustic effect. For example, the laser wavelength may be between 500 nm and 1350 nm or any wavelength therebetween, more preferably from between 650 nm and 1270 nm or any wavelength therebetween, or preferably 1064 nm at 1 photonexcitation and 532 nm at 2 photon excitation for carbon black, and between 650 nm and 900 nm or any wavelength therebetween, preferably 660 nm for the black hole quencher.

[0309] The steps 210, 220 and 230 are preferably provided in the given sequence.

[0310] The application of the modified aptamers is preferably provided as a transdermal injection, such as a needle-based injection, a high-pressure jet injection, a cream, a patch, a lotion or the like.

[0311] Preferably, the step 230 of irradiating laser light to the target macrophages is repeated after a predetermined time. The predetermined time is preferably less than 5 minutes, in particular less than 1 minute, as for example less than 20 seconds.

[0312] The wavelength of the laser light that is used for the radiation of the target macrophages is preferably larger than 600 nm, in particular larger than 700 nm. It is particularly advantageous when the wavelength of the laser light is in the optical window of the skin. The optical window of the skin is well-known to be a near-infrared window with wavelengths between 500 nm and 1350 nm. At these wavelengths light has its maximum depth of penetration in tissue. For example, the laser wavelength may be between 500 nm and 1350 nm or any wavelength therebetween, more preferably from between 650 nm and 1270 nm or any wavelength therebetween, or preferably 1064 nm at 1 photon excitation and 532 nm at 2 photon excitation for carbon black, and between 650 nm and 900 nm or any wavelength therebetween, preferably 660 nm for the black hole quencher.

[0313] The method 200 can comprise further steps, such as further diagnostic steps and / or steps concerning a preparation of the human skin including the dermis, a sweat gland or a sebaceous gland for the application of the modified aptamers.

[0314] Preferably, the method 200 is used for tattoo removal, for skin tag removal, for cancer therapy, for acne therapy, cellulite treatment, hyperhidrosis treatment, or treatment of stretch marks or scars or the like. Such applications can make use of the photoacousticeffect that can lead to a destruction of the target macrophages due to the radiation of the modified aptamers with laser light. Such a destruction of the target macrophages can support a removal of particles in these macrophages away from the human skin. Therefore, color particles of a tattoo, skin tag objects, certain molecules related to cancer and / or the like can be removed from the human skin and thereby lead to a progress in said possible applications.

[0315] Example 7

[0316] Fig. 4 shows the effect of the method 200 according to the invention on the target macrophages 310 in the human skin including the dermis, a sweat gland or a sebaceous gland 305.

[0317] The schematic illustration in Fig. 4 points out a process. At a first point in time during step 230 of the previously mentioned method 200, laser light 320 reaches the target macrophages 310 with the modified aptamers 315. The modified aptamers 315 have a certain influence on the optical characteristics of the attached target macrophages 310 and lead to an excitation of these macrophages 310 due to the optoacoustic effect. The optoacoustic effect, also called photoacoustic effect, is based in the effect of pulsed light on a material sample. Laser light 320 is via definition pulsed light and therefore suitable for supporting the optoacoustic effect. At a second point in time after the first point in time, the excited target macrophages 310 disintegrate as a reaction to the optoacoustic effect and thereby free particles 330, such as colored particles, that have been kept inside the target macrophages 310. At a third point in time after the second point in time, the former target macrophage 310 has lost its structure and all of the particles 330 so that the particles can be further processed by the human body and thereby transported away from the skin 305.

[0318] Example 8

[0319] Fig. 5 shows an embodiment of a system 400 for targeting specific tissue, in particular for providing a dermatological therapy and / or diagnostic for human skin including the dermis, a sweat gland or a sebaceous gland, according to the invention.The system 400 comprises a library of randomized oligonucleotide sequences 440 in order to provide the SELEX process for the target macrophages in the human skin including the dermis, a sweat gland or a sebaceous gland 305.

[0320] The system 400 further comprises a microfluidic analysis device 450 that is at least configured to amplify the aptamers within the SELEX process and to identify the synthesized aptamers.

[0321] Finally, the system 400 further comprises a laser device 460 that is arranged and configured to irradiate the human skin including the dermis, a sweat gland or a sebaceous gland 305 with the target macrophages in vivo with laser light 320, wherein a wavelength of the laser light 320 depends on the targeted quencher applied to the synthesized aptamers in order to enable specific tissue destruction through the photoacoustic effect. For example, the laser wavelength may be between between 500 nm and 1350 nm or any wavelength therebetween, more preferably from between 650 nm and 1270 nm or any wavelength therebetween, or preferably 1064 nm at 1 photon excitation and 532 nm at 2 photon excitation for carbon black, and between 650 nm and 900 nm or any wavelength therebetween, preferably 660 nm for the black hole quencher.

[0322] Preferably, the laser device 460 is a tunable laser device.

[0323] In a preferred variant, the system 400 is used for the removal of a tattoo 470 on the human skin 305. Colour particles of the tattoo 470 rest within the macrophages in the human skin and stay there even when macrophages where replaced by a new generation of macrophages during the aging process of the skin. The destruction of the macrophages can lead to the removal of the color particles within the human body. Therefore, the system 400 as shown in Fig. 5 can lead to an improved removal of the tattoo 470 by destroying the target macrophages using the optoacoustic effect of the pulsed laser light 320.

[0324] Example 9 - Ex vivo evidence of specific macrophage targeting for tattoo removalFig. 6 shows the result from an ex vivo, full-thickness skin model incorporating macrophage co-culture where the tattoo process was performed as described in Lin et al., 2023.

[0325] In brief, the skin was tattooed with Nile Red as the tattoo dye. Quencher was then applied topically in two formulations as described in Example 2: one with peptide (P) targeting and the other with aptamer (A) targeting. The formulations were applied once daily for four days. On the eighth day, the skin was harvested, followed by histology and staining. The results show that the macrophages were tattooed successfully with Nile Red, which is evidenced in the sub-epidermal macrophages as detected by staining with macrophage markers CD68 and CD163 as well as Nile Red stain CY5. Upon quencher application, whether peptide- or aptamer-targeted, there was Nile Red (i.e. tattoo) quenching, observed as CY5 fluorescence suppression.

[0326] Importantly, the results also demonstrate that the two quencher formulations do not generally penetrate the skin but instead specifically target the macrophages, particularly the tattooed ones. Since the macrophages take up the quencher, there is observed fluorescence suppression during microscopy.

[0327] Example 10 - In vivo evidence of tattooed macrophage targeting by the quencher for tattoo removal

[0328] Fig. 7 A1, A2 and B1, B2 show the results of in vivo treatment of skin with the quencher formulation. A1 and B1 are prior to application of the quencher formulation and A2 and B2 are 12 hours after application of the quencher formulation.

[0329] Specifically, it can be observed that the quencher formulation specifically targets tattooed macrophages containing a black tattoo pigment which is evidenced by the selective darkening of the tattooed area, intensifying the black of the monochromatic tattoo.This demonstrates that the system functions in vivo in skin perfused with the quencher formulation, and that there is directed cell targeting, while also demonstrating excellent skin penetration. The quencher formulation was applied to the skin just once, where it rapidly absorbed, with the effect becoming visible between 12 and 24 hours after application.

[0330] Example 11 - In vivo evidence of tattoo removal though macrophage targeting by the quencher

[0331] Fig. 8 shows the results of in vivo treatment of a tattoo with the quencher formulation.

[0332] A is prior to application of the quencher formulation comprising the aptamer targeting system as described above in Example 3, B is after the first application of the quencher formulation as described above in Example 3 and laser treatment, and C is after the second application of the quencher formulation as described above in Example 3 and laser treatment.

[0333] The laser settings used with the Picosecond laser were:

[0334] 1. Wavelength: 1064 nm

[0335] 2. Pulse Duration: 450 ps

[0336] 3. Fluence: 0.3 J / cm2

[0337] 4. Spot Size: 5 mm.

[0338] Example 12 - manufacture of a targeted photoacoustic system for hair removal

[0339] A targeted photoacoustic system for hair removal was manufactured using the following steps:

[0340] i) identifying one or more hair follicles;

[0341] ii) selecting and synthesizing one or more tags targeting hair follicles; including from a subject having a fair hair colour or fair skin characterized by low levels of eumelanin, resulting in hair shades that can range from light blonde to light brown,the tags being in the form of palmitoyl (PALM) tags having peptide sequences for hair follicle targeting selected from the group consisting of SEQ ID NOs: 150-219 (optionally conjugated to a skin penetrating peptide tag sequence to facilitate transdermal transport of the photoacoustic compound, the skin penetrating peptide tag being selected from any one of any one of SEQ ID NOS: 136-142);

[0342] iii) providing a photoacoustic compound in the form of a carbon black nanoparticle;

[0343] iv) providing a functionalized Palm-Tagged PHEROID Vesicle delivery system as described in Example 3 (optionally conjugating the palm-tag peptide to a skin penetrating peptide tag sequence to facilitate transdermal transport of the photoacoustic compound, the skin penetrating peptide tag being selected from any one of any one of SEQ ID NOS: 136-142), and

[0344] vi) formulating the photoacoustic compound within the functionalized Palm-Tagged PHEROID Vesicle delivery system by encapsulation within the delivery system;

[0345] thereby to form the targeted photoacoustic system.

[0346] Once the targeted photoacoustic system has been formed, then it can be applied to the skin.

[0347] Example 13 - in vivo evidence of follicle targeting

[0348] With reference to Figure 9, a nanoemulsion comprising the targeted photoacoustic system of Example 12 above was manufactured. The PALM tag anchored within the lipid layer of the PHEROID vesicles was conjugated to a skin-penetrating peptide tag sequence. Optionally, an emulsifying agent such as xanthan gum was added to the PHEROID vesicles during manufacture.

[0349] Once manufactured, the nanoemulsion was topically applied to a subject having a fair hair colour or fair skin characterized by low levels of eumelanin. During preparation, the nanoemulsion formed stable vesicular particles with a mean diameter below 300nm as determined by dynamic light scattering. The tags were incorporated into the lipid layer of the nanoemulsion, thereby exposing the follicle-targeting sequence on the particle surface. The photoacoustic compound in the form of carbon black nanoparticles was encapsulated within the PHEROID vesicles during formulation to ensure retention within the nanoemulsion and prevent nonspecific surface deposition.

[0350] The nanoemulsion formulation was then applied topically to the volar forearm skin of a healthy adult volunteer with predominantly blond hair. Prior to application, the skin surface was gently cleaned using an alcohol swab. The nanoemulsion was then evenly distributed across the target area and left to incubate for 10 minutes under occlusion-free conditions. After an incubation period if 5,10 or 20 minutes the skin surface was gently cleaned using water and mild mechanical wiping to remove residual formulation from the stratum corneum while leaving material retained within hair follicles unaffected. Macroscopic and close-range photographic documentation of the treated skin areas was performed before application and after incubation and cleaning. Images were recorded under identical lighting conditions to allow direct visual comparison of follicular staining patterns.

[0351] Results

[0352] Following topical application and incubation of the nanoemulsion, a clear and selective accumulation of the photoacoustic compound within hair follicles was observed. Prior to treatment, blond hair follicles were only weakly visible against the surrounding skin, showing minimal intrinsic contrast (Figure 9A). However, after a 10-minute incubation with the targeted nanoemulsion and subsequent cleaning of the skin surface, individual hair follicles appeared distinctly darkened, while the surrounding epidermis remained largely unstained (Figure 9B). The observed staining pattern was spatially confined to the follicular openings and hair shafts, indicating preferential accumulation of the photoacoustic compound within the follicular compartment rather than nonspecific surface deposition.

[0353] No visible diffuse skin discoloration or background staining was detected after washing, supporting selective follicular retention of the photoacoustic compound. Thecontrast enhancement was particularly pronounced in blond hair follicles, which normally lack sufficient endogenous melanin for effective optical targeting.

[0354] Discussion and conclusion

[0355] Laser and intense pulsed light (IPL) hair removal depend on melanin as the dominant endogenous chromophore to achieve selective photothermolysis of the follicular unit which inherently limits efficacy when melanin is absent or markedly reduced (Anderson & Parrish, 1983; Ibrahimi, 2011). For example, the laser wavelength may be between 500 nm and 1350 nm or any wavelength therebetween, preferably 1064 nm at 1 photon excitation and 532 nm at 2 photon excitation for carbon black, and between 650 nm and 900 nm or any wavelength therebetween, preferably 660 nm for the black hole quencher.

[0356] Accordingly blond, white and grey hair and mixed / transition hair during greying are widely recognized as difficult or non-responsive targets for conventional photoepilation (Ibrahimi, 2011). From a population standpoint, greying is extremely common in the core consumer age band with a worldwide survey reporting that 74% of individuals aged 45–65 years show grey hair (Panhard et al., 2012) and population-based data summarized in a dermatology review indicate that 6–23% of people have ~50% grey hair by age 50 (Kumar et al., 2018).

[0357] In parallel, naturally blond hair is often cited as a small but non-trivial global fraction (≈2% of the world population) (World Population Review, 2025). This creates a sizable “currently under-served” segment within a large and growing hair-removal economy: the global laser hair removal market has been estimated at USD 1.22B (2024) and projected to USD 1.42B (2025) (Fortune Business Insights, 2024), while the global hair removal devices market (including consumer devices) was valued at USD 1.32B (2023) (Grand View Research, 2024) and the at-home IPL device market at USD 1.52B (2024) (The Business Research Company, 2025).

[0358] Follicle-selective deposition of an exogenous photoacoustic compound (i) functionally substitutes for missing melanin, (ii) provides visual confirmation of target engagementvia localized follicular darkening, and (iii) can enable effective treatment at lower fluence, improving safety margins and enabling broader home-use and low-energy device applicability (Anderson & Parrish, 1983; Ibrahimi, 2011).

[0359] Such a follicle-targeted photoacoustic compound approach may also be advantageous for naturally dark hair, as it allows optical contrast to be further concentrated specifically at the follicular level, exceeding the effective absorption of endogenous melanin alone. By increasing localized follicular absorbance relative to surrounding tissue, required energy levels can be reduced while maintaining or improving efficacy, which is particularly relevant for darker skin types where epidermal melanin otherwise limits safe fluence. This enhanced targeting is likewise highly relevant for home-use devices operating under strict regulatory energy constraints, where improved follicular contrast can translate directly into higher efficiency at low output power.

[0360] Beyond epilation, selective follicle staining with a chromophore rather than a photoacoustic compound can e.g. support procedural precision in hair transplantation by improving visualization of donor and recipient sites and reducing the risk of inadvertently injuring dormant or miniaturized follicles (Bernstein & Rassman, 1997). Such a technology could also, in principle, be applied as a novel and potentially less harmful approach to hair dyeing, wherein the hair follicle is selectively targeted first and an organic, non-toxic colorant is subsequently introduced via the follicular pathway into the growing hair shaft, enabling pigmentation from within rather than through repeated external surface treatments.

[0361] The result obtained in this example accordingly demonstrates that the follicle-targeted nanoemulsion enables rapid and selective marking of hair follicles with a strongly absorbing material under mild topical conditions. The accumulation of carbon-based or equivalent photoacoustic compounds within the follicular unit provides a localized optical target suitable for subsequent low-fluence laser or intense pulsed light exposure, thereby supporting a targeted hair removal approach with reduced energy requirements as well as enabling other procedures such as hair transplantation.LIST OF REFERENCE SIGNS

[0362] 100, 200 method

[0363] 110, 120, 130, 210, 220, 230 steps of the method

[0364] 305 human skin

[0365] 310 target macrophage

[0366] 315 modified aptamers

[0367] 320 laser light

[0368] 330 particles

[0369] 400 system

[0370] 440 library of randomized oligonucleotide sequences 450 microfluidic analysis device

[0371] 460 laser device

[0372] 470 tattoo

[0373] References

[0374] Anderson RR, Parrish JA. The optics of human skin. J Invest Dermatol. 1981;77(1):13-19.

[0375] Anderson, R. R. & Parrish, J. A. (1983). Selective photothermolysis: precise microsurgery by selective absorption of pulsed radiation. Science, 220(4596), pp. 524-527.

[0376] Baranska A, Shawket A, Jouve M, et al. Unveiling skin macrophage dynamics explains both tattoo persistence and strenuous removal. J Exp Med. 2018;215(4): 1115-1133.

[0377] Bernstein RM, Rassman WR. Follicular transplantation: patient evaluation and surgical planning. Dermatol Surg. 1997;23(9):771-784.Fabriek BO, Dijkstra CD, van den Berg TK. The macrophage scavenger receptor CD163. Immunobiology. 2005;210(2): 153-160. doi:10.1016 / j.imbio.2005.05.010

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[0379] Kerrigan AM, Dennehy KM, Mourao-Sa D, et al. CLEC-2 Is a Phagocytic Activation Receptor Expressed on Murine Peripheral Blood Neutrophilsl. The Journal of Immunology. 2009; 182(7):4150-4157. doi:10.4049 / jimmunol.0802808

[0380] Fortune Business Insights (2024). Laser Hair Removal Market Size, Share & Growth Report.

[0381] Grand View Research (2024). Hair Removal Devices Market Size Report, 2024-2030.

[0382] Grobler, A. F., Kotze, A. F., Du Plessis, J. 2008. The Design of a Skin-Friendly Carrier for Cosmetic Compounds Using Pheroid Technology. Science and Applications of Skin Delivery Systems. Ed J Wiechers. Allure Publications: 413-458.

[0383] Grobler, A. F. 2009. Pharmaceutical applications of Pheroid™ technology. Published. PhD dissertation, North-West University. Roberts S, Strome A, Choi C, et al. Acid specific dark quencher QC1 pHLIP for multi-spectral optoacoustic diagnoses of breast cancer. Scientific Reports. 2019;9(1):8550. doi: 10.1038 / s41598-019-44873-1

[0384] Ibrahimi, O. A. (2011). Laser hair removal. Dermatologic Therapy, 24(1), pp. 94–107.

[0385] Kumar, A. B., Shamim, H. & Nagaraju, U. (2018). Premature graying of hair: Review with updates. International Journal of Trichology, 10(5), pp. 198-203.

[0386] Lin C, Marquardt Y, Rütten S, Liao L, Rahimi R, Haraszti T, Baron JM, Bartneck M.

[0387] 2023. Macrophage-like rapid uptake and toxicity of tattoo ink in human monocytes. Immunology. 2024;171:388-401. doi:10.1111 / jmm.13714

[0388] Panhard, S., Lozano, I. & Loussouarn, G. (2012). Greying of the human hair: a worldwide survey, revisiting the ‘50’ rule of thumb. British Journal of Dermatology, 167(4), pp. 865-873.Siemion IZ, Kluczyk A. Tuftsin: On the 30-year anniversary of Victor Najjar’s discovery. Peptides. 1999;20(5):645-674. doi: 10.1016 / S0196-9781 (99)00019-4

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[0390] Stanley ER, Chitu V. CSF-1 receptor signaling in myeloid cells. Cold Spring Harb Perspect Biol. 2014;6(6). doi:10.1101 / cshperspect.a021857

[0391] Taban Q, Mumtaz PT, Masoodi KZ, Haq E, Ahmad SM. Scavenger receptors in host defense: from functional aspects to mode of action. Cell Communication and Signaling.

[0392] 2022;20(1):2. doi:10.1186 / s12964-021-00812-0

[0393] Taylor PR, Gordon S, Martinez-Pomares L. The mannose receptor: linking homeostasis and immunity through sugar recognition. Trends in Immunology.

[0394] 2005;26(2): 104-110. doi:10.1016 / j.it.2004.12.001

[0395] The Business Research Company (2025). At-Home IPL Device Global Market Report.

[0396] Uys, C. E. 2006. Preparation and characterization of Pheroid vesicles. Potchefstroom: NWU. (Dissertation-M. Sc). 147p.

[0397] Wang Y, Niu G, Zhai S, Zhang W, Xing D. Specific photoacoustic cavitation through nucleus targeted nanoparticles for high-efficiency tumor therapy. Nano Research.

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[0399] World Population Review (2025). Blonde Hair Percentage by Country I Global prevalence discussion.

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Claims

CLAIMS1. A targeted delivery system comprising or consisting of:at least one targeting motif and / or at least one tag for targeting at least one cell population;at least one compound selected from the group consisting of at least one chromophore or at least one photoacoustic compound having an absorption maximum within the optical window of the skin comprising an absorption maximum selected from between 500 nm and 1350 nm or any wavelength therebetween;at least one delivery system,wherein the at least one targeting motif and / or the at least one tag is conjugated to the at least one compound with at least one linker, and / or is displayed on a surface of the at least one delivery system, andwherein the at least one compound is encapsulated or comprised within the at least one delivery system.

2. The targeted delivery system according to claim 1, comprising or consisting of:at least one targeting motif and / or at least one tag for targeting at least one cell population;at least one compound selected from the group consisting of at least one chromophore or at least one photoacoustic compound having an absorption maximum within the optical window of the skin comprising an absorption maximum selected from between 500 nm and 1350 nm or any wavelength therebetween, conjugated to the at least one targeting motif and / or the at least one tag with at least one linker; andat least one delivery system,wherein the targeting motif and / or tag -conjugated compound is encapsulated or comprised within the at least one delivery system such that the targeting motif and / or tag is displayed on its surface.

3. The targeted delivery system according to claim 1, comprising or consisting of:at least one targeting motif and / or at least one tag for targeting at least one cell population;at least one compound selected from the group consisting of at least one chromophore or at least one photoacoustic compound having an absorption maximum within the optical window of the skin comprising an absorption maximum selected from between 500 nm and 1350 nm or any wavelength therebetween; andat least one delivery system functionalised to display the at least one targeting motif and / or tag on its surface and encapsulating the at least one compound.

4. The targeted delivery system according to claim 1, comprising or consisting of:at least one targeting motif conjugated with at least one linker to at least one tag;at least one compound selected from the group consisting of at least one chromophore or at least one photoacoustic compound having an absorption maximum within the optical window of the skin comprising an absorption maximum selected from between 500 nm and 1350 nm or any wavelength therebetween; andat least one delivery system functionalised to display the conjugated targeting motif and tag on its surface and encapsulating the at least one compound.

5. The targeted delivery system according to any one of claims 1 to 4, wherein the at least one photoacoustic compound is a dark quencher selected from the group comprising of a Black Hole Quencher (BHQ) selected from the group comprising or consisting of Black Hole Quencher-1 (BHQ-1), BHQ-2, BHQ-3, Black Berry Quencher-650 (BBQ-650), BMN Quencher 460 (BMN-Q460), BMN-Q535, BMN- Q1, BMN-Q2, BMN-Q590, BMN-Q620, BNM-Q651 or Dabcyl.

6. The targeted delivery system according to any one of claims 1 to 4, wherein the at least one chromophore or at least one photoacoustic compound is a nanoparticle, selected from a gold nanoparticle or a carbon black nanoparticle.

7. The targeted delivery system according to any one of claims 1 to 4, wherein the at least one chromophore or the at least one photoacoustic compound is a carbon black nanoparticle.

8. The targeted delivery system according to any one of claims 1 to 7, wherein the at least one targeting motif and / or tag is selected from the group consisting of nucleotide aptamers, peptide aptamers, peptides, Peptide Nucleic Acid Oligomers (PNAOs), L-ribonucleic acid aptamer (or Spiegelmer), antibodies, antibody fragments and nanobodies.

9. The targeted delivery system according to any one of claims 1 to 8, wherein the at least one targeting motif is a nucleotide aptamer comprising or consisting of:(A) a nucleotide sequence having at least 75%, or at least 80% sequence identity, or at least 85% sequence identity, or at least 90% sequence identity, or at least 95% sequence identity, or up to 100 % sequence identity to any one of SEQ ID NOs: 1-119 or any sequence identity therebetween, or any nucleotide sequence capable of hybridising under stringent conditions to said nucleotide sequence, or any said nucleotide sequence or said nucleotide sequence capable of hybridising under stringent conditions that is adapted to form a Peptide Nucleic Acid Oligomer (PNA), or L-ribonucleic acid aptamer; or(B) a nucleotide sequence having at least 75%, or at least 80% sequence identity, or at least 85% sequence identity, or at least 90% sequence identity, or at least 95% sequence identity, or up to 100 % sequence identity of GAAGAGTCGATGTAACGTTTTTTCGCACGATAATAGGGACGTGAGTCAGACA (SEQ ID NO: 8) or any sequence identity therebetween, or any nucleotide sequence capable of hybridising under stringent conditions to SEQ ID NO: 8, or is a nucleotide sequence having at least 75%, or at least 80% sequence identity, or at least 85% sequence identity, or at least 90% sequence identity, or at least 95% sequence identity, or up to 100 % sequence identity, or any sequence identity therebetween, or any said nucleotide sequence or said nucleotide sequence capable of hybridising under stringent conditions that is adapted to form a Peptide Nucleic Acid Oligomer (PNA), or L-ribonucleic acid aptamer.

10. The targeted delivery system according to any one of claims 1 to 8, wherein the at least one targeting motif is a peptide aptamer for macrophage targeting, comprising or consisting of an amino acid sequence having at least 75%, or at least 80% sequence identity, or at least 85% sequence identity, or at least 90% sequence identity, or at least 95% sequence identity, or up to 100 % sequence identity, or any sequence identity therebetween to any one of SEQ ID NOs: 120- 135.

11. The targeted delivery system according to any one of claims 1 to 8, wherein the at least one targeting motif or the at least one tag is a skin-penetrating peptide, comprising or consisting of an amino acid sequence having at least 75%, or at least 80% sequence identity, or at least 85% sequence identity, or at least 90% sequence identity, or at least 95% sequence identity, or up to 100 % sequence identity, or any sequence identity therebetween to any one of SEQ ID NOs: 136- 142.

12. The targeted delivery system according to any one of claims 1 to 8, wherein the at least one targeting motif or the at least one tag is a peptide for macrophage targeting selected from the group comprising or consisting of: macrophage colony stimulating factor (M-CSF); colony-stimulating factor-1; mannose; scavenger receptor A (SR-A); C-type lectin receptor 2 (CLE2); or at least one human antibody.

13. The targeted delivery system according to any one of claims 1 to 8, wherein the at least one targeting motif or the at least one tag is a peptide for hair follicle targeting.

14. The targeted delivery system according to claim 13, wherein the peptide for hair follicle targeting is selected from the group comprising or consisting of SEQ ID NOs: 150-219 or having at least 75%, or at least 80% sequence identity, or at least 85% sequence identity, or at least 90% sequence identity, or at least 95%sequence identity, or up to 100 % sequence identity, or any sequence identity therebetween to any one of SEQ ID NOs: 150-219.

15. The targeted delivery system according to any one of claims 1 to 14, wherein the at least one targeting motif is a peptide sequence for macrophage targeting or a peptide sequence for hair follicle targeting that is further adapted by conjugation to a skin-penetrating peptide tag, thereby to facilitate transdermal transport of the photoacoustic compound.

16. The targeted delivery system according to any one of claims 1 to 15, wherein the at least one linker is selected from the group comprising or consisting of a polyethylene glycol (PEG) linker, a glycine-serine (GS) linker, a maleimide linker, a fatty acid linker, a hyaluronic acid linker, a succinic acid linker, a peptide linker, or a cleavable linker, or any combination thereof.

17. The targeted delivery system according to claim 16, wherein the at least one linker is selected from the group comprising or consisting of an amino acid sequence selected from any one of the following: Glycine-Glycine-Glycine (GGG); Glycine-Serine-Glycine (GSG); EAAAK(SEQ ID NO: 143); GSTSG (SEQ ID NO: 144); GGSGG (SEQ ID NO: 145); (Gly4Ser)n(SEQ ID NO: 146); (Ser- Gly)5(SEQ ID NO: 147); K(GGGGS)n (SEQ ID NO: 148); or SGGGG (SEQ ID NO: 149).

18. The targeted delivery system according to any one of claims 1 to 17, wherein the at least one tag is a lipophilic tag including a palmitoyl (PALM)-motif and / or is a heterobifunctional tag including a heterobifunctional tag linked to an additional diagnostic or therapeutic agent.

19. The targeted delivery system according to claim 18, wherein the at least one tag is a palmitoyl (PALM) tag.

20. The targeted delivery system according to any one of claims 1 to 19, wherein the delivery system is selected from the group comprising or consisting ofnanoparticles, liposomes or other lipid-like vesicle carriers including lipid nanoparticles (LNPs), liposomes, or other lipid-like vesicle carriers including a nanoemulsion.

21. The targeted delivery system according to any one of claims 1 to 19, wherein the delivery system is a polymer hydrogel.

22. The targeted delivery system according to any one of claims 1 to 21, wherein the one or more targeting motifs and / or one or more tags target one or more cell types, including macrophage cells, cells located in the dermis, hair follicles, a sebaceous gland or a sweat gland.

23. The targeted delivery system according to any one of claims 1 to 22, wherein the least one photoacoustic compound is a quencher, and the quencher is selected to be targeted to a characteristic of a molecule to be targeted, including as the colour of a molecule present in target macrophages in human skin, further including coloured ink molecules forming a tattoo.

24. The targeted delivery system according to any one of claims 1 to 23, which is formulated as a composition for delivery by transdermal injection, high-pressure jet injection, cream, patch or lotion.

25. The targeted delivery system according claim 24, which is formulated as a composition further comprising one or more additives or pharmaceutically or cosmetically acceptable excipients selected from the group comprising one or more moisturizers including glycerin (5%) and / or hyaluronic acid (0.5%) to improve skin hydration and comfort during treatment, one or more stabilizers and / or preservatives including tocopherol acetate (Vitamin E, 1%) and phenoxyethanol (0.5%), one or more synthetic or natural antimicrobial, antiinflammatory or antioxidant compounds or compositions including essential oils selected from the group comprising aloe vera, or tea tree oil, one or more emulsifying agents including xanthan gum, or one or more chelating agents including deferiprone, or EDTA.

26. The targeted delivery system according to any one of claims 1 to 25, wherein the at least one cell population is a macrophage cell population, or a cell population located in the dermis, or is a macrophage cell population located in the dermis or is a hair follicle cell population.

27. The targeted delivery system according to claim 1, comprising or consisting of:(i) at least one targeting motif and at least one tag selected from the group comprising or consisting of at least one nucleotide aptamer, at least one peptide aptamer, or at least one peptide sequence for targeting at least one cell population selected from a cell population located in the dermis, a macrophage cell population, a macrophage cell population located in the dermis, sebaceous gland or sweat gland, or a hair follicle cell population including a hair follicle of a subject having a fair hair colour or fair skin characterized by low levels of eumelanin, resulting in hair shades that can range from light blonde to light brown;(ii) the at least one targeting motif being conjugated to at least one linker selected from any one of SEQ ID NOs 143-149;(iii) at least one chromophore or photoacoustic compound selected from carbon black or a black hole quencher including BMN-Q651 having an absorption maximum within the optical window of the skin selected from between 500 nm and 1350 nm or any wavelength therebetween, conjugated to the at least one targeting motif by the at least one linker; and(v) at least one delivery system selected from a lipid-based system, including a lipid nanoparticle (LNP), liposome, or other lipid-like vesicle carrier including a nanoemulsion, functionalised to display the at least one tag on its surface and encapsulating the at least one targeting motif-conjugated chromophore or photoacoustic compound, or a polymer hydrogel, including a polymer hydrogel formulated as a hydrogel patch comprising the at least one at least one tag and the at least one targeting motif-conjugated chromophore or photoacoustic compound.

28. The targeted delivery system according to claim 1, comprising or consisting of: (aa) at least one targeting motif and / or tag selected from the group comprising or consisting of at least one nucleotide aptamer, at least one peptide aptamer, or at least one peptide sequence for targeting at least one cell population selected from a cell population located in the dermis, a macrophage cell population, a macrophage cell population located in the dermis, sebaceous gland or sweat gland, or a hair follicle cell population including of a subject having a fair hair colour or fair skin characterized by low levels of eumelanin, resulting in hair shades that can range from light blonde to light brown,(bb) optionally the at least one tag being conjugated to the at least one targeting motif by at least one linker selected from any one of SEQ ID NOs 143- 149;(cc) at least one chromophore or photoacoustic compound selected from carbon black or a black hole quencher incouding BMN-Q651 having an absorption maximum within the optical window of the skin selected from between 500 nm and 1350 nm or any wavelength therebetween; and(dd) at least one delivery system selected from a lipid-based system, including a lipid nanoparticle (LNP), liposome, or other lipid-like vesicle carrier including a nanoemulsion, functionalised to display the at least one targeting motif, the at least one tag, or the at least one tag-conjugated targeting motif on its surface and comprising the at least one chromophore or photoacoustic compound, or a polymer hydrogel, including a polymer hydrogel formulated as a hydrogel patch comprising the at least one targeting motif, the at least one tag, or the at least one tag-conjugated targeting motif and the at least one chromophore or photoacoustic compound.

29. The targeted delivery system according to claim 27 or 28, wherein the at least one targeting motif is a nucleotide aptamer selected from the group consisting of any one of SEQ ID NOS: 1-119; a macrophage targeting peptide aptamerselected from the group consisting of any one of SEQ ID NOS: 120-135; a skin penetrating peptide selected from the group consisting of SEQ ID NOs: 136 to 142; or a hair follicle targeting peptide selected from the group consisting of SEQ ID NOs: 150 to 219.

30. The targeted delivery system according to claim 29 which is for hair follicle targeting including from a subject having a fair hair colour or fair skin characterized by low levels of eumelanin, resulting in hair shades that can range from light blonde to light brown, wherein the photoacoustic compound is a nanoparticle selected from a gold nanoparticle or a carbon black nanoparticle.

31. The targeted delivery system according to claim 29 which is for macrophage targeting, wherein the photoacoustic compound is a black hole quencher including BMN-Q651.

32. The targeted delivery system according to any one of claims 27 or 31, wherein the at least one tag is a skin penetrating peptide tag or a lipophilic tag including a palmoyl (PALM)-tag.

33. A pharmaceutical or cosmetic composition comprising the targeted photoacoustic system according to any one of claims 1 to 32 and optionally a pharmaceutically acceptable excipient including one or more chelating agents comprising deferiprone or EDTA.

34. A device for treating a skin or hair-associated disease or condition, for removal of tattoos, or both, the device comprising:a reservoir containing the targeted delivery system according to any one of claims 1 to 32 or the pharmaceutical or cosmetic composition according to claim 33;an applicator for applying the targeted delivery system or composition to the skin;an illuminator, for illuminating skin with a specified frequency of light; andoptionally a computer comprising a computer program to operate the device.

35. The device according to claim 34, wherein the skin-associated disease or condition is comprised of the group selected from acne, scars, stretch marks, cellulite, hyperhidrosis, removal of skin tags, facilitating skin-tightening, or skin cancer.

36. The device according to claim 35, wherein the treatment for the hair-associated disease or condition is selected from the group comprising hair removal, colour treatment and hair regrowth, including in subjects having a fair hair colour or fair skin characterized by low levels of eumelanin, resulting in hair shades that can range from light blonde to light brown.

37. The device according to any one of claims 34 to 36, wherein the applicator is a transdermal injector, or high-pressure jet injector.

38. The device according to any one of claims 34 to 37, wherein the illuminator is a laser including a pulse laser, or a Q-switched pulse laser.

39. The device according to any one of claims 34 to 38, wherein the treating comprises illuminating the skin with the illuminator for less than 5 minutes, less than 1 minute, or less than 20 seconds.

40. The device according to any one of claims 34 to 39, wherein the specified frequency of light has a frequency within the optical window of the skin, selected from between 650 nm and 1350 nm or any wavelength therebetween.

41. A kit comprising the targeted delivery system according to any one of claims 1 to 32 or the pharmaceutical or cosmetic composition according to claim 33, or the device according to any one of claims 34 to 40; one or more reagents; and optionally instructions for use.

42. A targeted delivery system according to any one of claims 1 to 32, a pharmaceutical or cosmetic composition according to claim 33, a device according to any one of claims 34 to 40, or a kit according to claim 41 for use in a method of targeting at least one cell population including a macrophage cell population, or at least one cell population located in the dermis, or a macrophage cell population located in the dermis, or a hair follicle cell population including a subject having a fair hair colour or fair skin characterized by low levels of eumelanin, resulting in hair shades that can range from light blonde to light brown.

43. A targeted delivery system according to any one of claims 1 to 32, a pharmaceutical or cosmetic composition according to claim 33, a device according to any one of claims 34 to 40, or a kit according to claim 41 for use in a method of treatment of a skin or hair-associated disease or condition, for removal of a tattoo, or both.

44. A targeted delivery system, pharmaceutical or cosmetic composition, device, or kit according to claim 43, wherein the skin-associated disease or condition is comprised of the group selected from acne, scars, stretch marks, cellulite, hyperhidrosis, removal of skin tags, facilitating skin-tightening, or skin cancer, the tattoo for removal is a monochromatic tattoo or a multichromatic tattoo, and the treatment of the hair-associated disease or condition is selected from the group comprising hair removal, colour treatment and hair regrowth, including in subjects having a fair hair colour or fair skin characterized by low levels of eumelanin, resulting in hair shades that can range from light blonde to light brown.

45. Use of a targeted photoacoustic system according to any one of claims 1 to 32 in the manufacture of a cosmetic or pharmaceutical composition or device for use in a method of treatment of a skin or hair-associated disease or condition, for removal of tattoos, or both.

46. The use of claim 45, wherein the skin-associated disease or condition is comprised of the group selected from acne, scars, stretch marks, cellulite, hyperhidrosis, removal of skin tags, facilitating skin-tightening, or skin cancer, thetattoo for removal is a monochromatic tattoo or a multichromatic tattoo, and the treatment of the hair-associated disease or condition is selected from the group comprising hair removal, colour treatment and hair regrowth, including in subjects having a fair hair colour or fair skin characterized by low levels of eumelanin, resulting in hair shades that can range from light blonde to light brown.

47. A method of preparation of a targeted delivery system according to any one of claims 1 to 32, the method comprising the steps of:i) identifying the at least one cell population for targeting;ii) providing the at least one chromophore or photoacoustic compound; iii) providing the at least one targeting motif and / or the at least one tag for targeting the at least one cell population;iv) A. conjugating the at least one targeting motif to the at least one chromophore or photoacoustic compound by the at least one linker, or B. optionally conjugating the at least one tag to the at least one targeting motif by at least one linker;v) providing the delivery system;vi) A. contacting the at least one targeting motif and / or the at least one tag or where present, the at least one tag-conjugated targeting motif with the delivery system, thereby to functionalise the delivery system to have the at least one targeting motif and / or at least one tag or the at least one tag- conjugated targeting motif displayed on its surface, and contacting the functionalised delivery system with the chromophore or photoacoustic compound thereby to encapsulate the chromophore or photoacoustic compound; orB. contacting the delivery system with the targeting motif-conjugated chromophore or photoacoustic compound, thereby to encapsulate or contain the targeting motif-conjugated chromophore or photoacoustic compound; or C. contacting the delivery system with the at least one tag, thereby to functionalise the delivery system to have the at least one tag displayed on its surface, and contacting the functionalised delivery system with the targeting motif-conjugated chromophore or photoacoustic compound,thereby to encapsulate the chromophore or photoacoustic compound and display the targeting motif on its surface,thereby to form the targeted delivery system.

48. The method according to claim 47, wherein the targeted delivery system is further comprised within a device or a kit.

49. The method according to either claim 47 or 48, wherein the at least one cell population for targeting is a cell population located in the dermis, or a macrophage cell population, or a macrophage cell population located in the dermis, or a hair follicle population including of a subject having a fair hair colour or fair skin characterized by low levels of eumelanin, resulting in hair shades that can range from light blonde to light brown.

50. A computer program for operating a system comprising program code means for causing a computer to carry out a method of targeting at least one cell population with the use of the device according to any one of claims 34 to 40.

51. A computer comprising the computer program according to claim 50, which forms an integrated part of a control unit of the system comprising program code and is implemented as a microcontroller or microprocessor.

52. A computer comprising the computer program according to claim 50, which forms an integrated part of a central unit that is spatially separated from the control unit of the system and is configured to control parts of the system and / or a number of further related apparatuses.

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