New compounds and uses thereof

Abstract

The invention relates to a compound of formula I, wherein: A, B, R1, R2, L1, m and n are as defined in the specification, or a salt or solvate thereof, which compounds are useful for forming Raman-tagged bioconjugates with a biomarker and / or biomolecule and are detectable with Raman spectroscopy

Description

[0001] NEW COMPOUNDS AND USES THEREOF Technical Field The present disclosure relates to compounds useful for Raman tagging of a biomarker and / or biomolecule. Associated Raman-tagged bioconjugates, uses, methods, kits of parts and processes are also disclosed. Background Raman spectroscopy is an analytical technique which allows for the identification of chemical functional groups based on the inelastic scattering of specific vibrational modes with light. As a result, Raman spectroscopy is used to characterise, among other categories of sample, biological samples for label-free imaging of particles, cells, and tissues etc., which can be differentiated based on their chemical compositions. Current methods using Raman spectroscopy can detect the class of biomolecules (e.g. proteins, DNA, RNA) but are unable to detect or differentiate specific biomolecules of interest, such as being able to differentiate between two (or more) different proteins. Single particle detection methods are of significant interest as they can be used to measure the intrinsic heterogeneity of biological samples which cannot be achieved with bulk measurements. Whilst label-free techniques have high utility (by measuring the native sample and through avoiding sample disruption, for example), due to the nature of Raman spectroscopy it is a challenge to differentiate chemical compounds of the same class, for example differentiating between different membrane bound proteins. To address this challenge, chemical compounds that show strong Raman signals can be bound to an appropriate targeting ligand (e.g. an antigen binding epitope). Ideally, these chemical compounds have Raman signals in the Raman silent region (1800-2800 cm-1), a privileged region with no Raman signals in most biological samples. Min and co-workers first reported Raman active imaging tags based on oligoyne (i.e. oligo- alkyne) derivatives (Nat Methods 15, 194–200 (2018); WO 2019 / 028430). This was the first report of using oligoynes for multiplexed Raman imaging. Multiplexing of the Raman active tags was clearly demonstrated; however, it was still a challenge to apply these tags for imaging non-lipid based biomolecules due to the poor solubility of the compounds in water due to their intrinsic hydrophobicity. Other general teachings in this area include: Tian, S., Li, H., Li, Z. et al. Nat Commun 11, 81 (2020), which describes polydiacetylene-based ultrastrong bioorthogonal Raman probes for targeted live-cell Raman imaging. WO 2005 / 031301 A2 relates to Raman signature probes and their use in the detection and imaging of molecular processes and structures; CN 105823770 A relates to optical-interference-free Raman labelling probe and preparation method and application thereof; WO 2020 / 182174 A1 relates to aggregation-induced emission, AIE, compounds with fluorescence, photoacoustic, and Raman properties; and WO 2011 / 078794 A1 relates to surface enhanced Raman spectroscopy-based, SERS-based, analyte detection. The inventors have now found novel compounds that are Raman tags that conjugate to biomarkers and biomolecules and enhance, through Raman techniques, the detection and analysis of said biomarkers and biomolecules (in particular, non-lipid based biomarkers and biomolecules) in biological samples. In this respect, pertinent performance metrics against which at least some examples of the present disclosure may be assessed are Raman signal strength and water solubility. The listing or discussion of a prior-published document or any background in this specification should not necessarily be taken as an acknowledgement that the document or background is part of the state of the art or is common general knowledge. One or more aspects / examples of the present disclosure may or may not address one or more of the background issues. Brief Description of the Figures The following drawings are provided to illustrate various aspects of the present inventive concept and are not intended to limit the scope of the present invention unless specified herein. Figure 1 shows spontaneous normalised Raman spectra of sulfonated oligoynes, according to an example. Figure 2 shows a representative example using Raman spectroscopy for detection of CD63 expressing extracellular vesicles. Figure 3 shows UV-Vis spectra of Raman-tagged bioconjugates, according to an example. Figure 4 shows a representative molecular weight trace of successful Herceptin bio- conjugation, according to an example. Figure 5 shows in schematic form an overview of an example process for biomolecule detection on single particles. Figure 6 shows a schematic diagram of an automated particle capture system for particle analysis, particularly applicable to Raman spectroscopic analysis, according to an example. Figure 7 shows an example process flow for automatic particle capture and data acquisition in accordance with the automated particle capture system of Figure 6. Figure 8 shows a flow diagram of a method of analysing a biological sample according to an example. Figure 9 shows a flow diagram of a method of detecting the presence or absence of a biomarker and / or biomolecule in a sample, according to an example. Figure 10 shows a flow diagram of a method of diagnosing a disease or disorder in a subject, according to an example. Figure 11 shows a flow diagram of an in vitro or ex vivo method of imaging a biological sample, according to an example. Detailed Description of the Invention According to the first aspect of the invention, there is provided a compound of formula I, wherein: A and B are each independently an aromatic group; each R1is independently selected from the group consisting of -S(O)2OH, -S(O)OH, -OS(O)2OH, -S(O)2NH2, -P(O)(OH)2, -OP(O)(OH)2, -P+(R3)3, -N+(R3)3, -OH, -C(O)OH, -NHC(O)OH, a 5- or 6-membered heterocyclylalkyl group, a 5- or 6-membered heteroaryl group, a zwitterionic group, and a PEG group; L1is a bond or a suitable linking group; R2is a group capable of being conjugated to a biomarker and / or biomolecule; each R3is independently selected from the group consisting of hydrogen and a C1-4alkyl group; m is 1, 2 or 3; and n is 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, or a salt or solvate thereof. These compounds, including salts and solvates thereof, may be referred to herein as the “compounds of the invention”. Salts of the compound of formula I may be prepared in accordance with techniques that are well known to those skilled in the art. For example, the compound of formula I may be reacted with the appropriate organic acid or mineral acid. Salt switching techniques may also be used to convert one salt into another salt. Examples of salts include base addition salts; metal salts formed with bases, for example, the sodium and potassium salts. Acid addition salts, for example, salts formed with inorganic acids such as hydrochloric, hydrobromic, sulfuric and phosphoric acid, with carboxylic acids or with organo-sulfonic acids may also be mentioned. The compounds disclosed herein may exist in unsolvated as well as solvated forms with solvents such as water, and it is intended that the invention embraces both solvated and unsolvated forms of the compounds of the invention. The term “solvate” refers to a complex of variable stoichiometry formed by a solute and solvent. Such solvents for the purpose of the invention may not interfere with the activity of the solute. Examples of suitable solvents include, but are not limited to, water, methanol, ethanol, and acetic acid. Solvates in which water is the solvent molecule are typically referred to as hydrates. Hydrates include compositions containing stoichiometric amounts of water, as well as compositions containing variable amounts of water. Compounds of formula I may contain double bonds and may thus exist as E (entgegen) and Z (zusammen) geometric isomers about each individual double bond. All such isomers and mixtures thereof are included within the scope of the invention. Compounds of the invention may also exhibit tautomerism. All tautomeric forms (or tautomers) and mixtures thereof are included within the scope of the invention. The term "tautomer" or "tautomeric form" refers to structural isomers of different energies which are interconvertible via a low energy barrier. For example, proton tautomers (also known as prototropic tautomers) include interconversions via migration of a proton, such as keto- enol and imine-enamine isomerisations. Valence tautomers include interconversions by reorganisation of some of the bonding electrons. Compounds of the invention may also contain one or more asymmetric (e.g. carbon or sulfur) atoms and may therefore exhibit optical and / or diastereoisomerism. Diastereoisomers may be separated using conventional techniques, e.g. chromatography or fractional crystallisation. The various stereoisomers may be isolated by separation of a racemic or other mixture of the compounds using conventional, e.g. fractional crystallisation or HPLC, techniques. Alternatively the desired optical isomers may be made by reaction of the appropriate optically active starting materials under conditions which will not cause racemisation or epimerisation (i.e. a ‘chiral pool’ method), by reaction of the appropriate starting material with a ‘chiral auxiliary’ which can subsequently be removed at a suitable stage, by derivatisation (i.e. a resolution, including a dynamic resolution), for example with a homochiral acid followed by separation of the diastereomeric derivatives by conventional means such as chromatography, or by reaction with an appropriate chiral reagent or chiral catalyst all under conditions known to the skilled person. All stereoisomers (including but not limited to diastereoisomers, enantiomers and atropisomers) and mixtures thereof (e.g. racemic mixtures) are included within the scope of the invention. In the structures shown herein, where the stereochemistry of any particular chiral atom is not specified, then all stereoisomers are contemplated and included as the compounds of the invention. Where stereochemistry is specified by a solid wedge or dashed line representing a particular configuration, then that stereoisomer is so specified and defined. Unless otherwise specified, alkyl groups defined herein may be straight-chain or, when there is a sufficient number (e.g. a minimum of three) of carbon atoms, be branched- chain. Alkyl groups that may be mentioned include methyl, ethyl, propyl, iso-propyl, butyl, and tert-butyl. When used herein, “alkylene” (i.e. alkanediyl) refers to a divalent alkyl group. Particular alkylene groups that may be mentioned include, for example, methylene (i.e. -CH2-). Alkenyl groups are unsaturated alkyl groups (i.e. having at least one carbon–carbon double bond). Unless otherwise specified, alkenyl groups defined herein may be straight-chain or, when there is a sufficient number (i.e. a minimum of two or three, as appropriate) of carbon atoms, be branched-chain. Alkenyl groups that may be used include ethenyl, propenyl, and butenyl groups. When used herein, “alkenylene” (i.e. alkenediyl) refers to a divalent alkenyl group. Particular alkylene groups that may be mentioned include, for example, -CH=CH-. Heterocycloalkyl groups that may be mentioned include non-aromatic monocyclic heterocycloalkyl groups in which at least one (e.g. one to four) of the atoms in the ring system is other than carbon (i.e. a heteroatom, e.g. sulphur, oxygen or, particularly, nitrogen), and in which the total number of atoms in the ring system is from four to six. The point(s) of attachment of heterocycloalkyl groups may be via any atom in the ring system including (where appropriate) a heteroatom (such as a nitrogen atom), or an atom on any fused carbocyclic ring that may be present as part of the ring system. Heterocycloalkyl groups may also be in the N- or S- oxidised form (i.e. those heteroatoms may be substituted with one or two =O substituents, as appropriate). For the avoidance of doubt, optional substituents include those defined herein. Heterocycloalkyl groups that may be mentioned include, but not limited to, pyrrolidinonyl, pyrrolidinyl, pyrrolinyl, pyranyl, pyrazolidinyl, tetrahydropyranyl, piperazinyl, piperidinyl, thiolanyl, sulfolanyl, thianyl and the like. Aromatic (i.e. aryl) groups that may be mentioned include C6-14 aryl groups (e.g. C6-10 aryl groups). Such groups may be monocyclic, bicyclic or tricyclic and have between 6 and 14 ring carbon atoms, in which at least one ring is aromatic. The points of attachment of aryl groups may be via any atom of the ring system. However, when aryl groups are bicyclic or tricyclic, they are linked to the rest of the molecule via an aromatic ring. C6-14 aryl groups include, but not limited to, phenyl, naphthyl, biphenyl, fluorenyl and the like. Unless otherwise specified, the term “heteroaryl” when used herein refers to an aromatic group containing one or more heteroatom(s) (e.g. one to four heteroatoms) preferably selected from N, O and S. Heteroaryl groups that may be mentioned include, but not limited to, pyrrolyl, imidazolyl, pyrazinyl, pyrazolyl, pyridazinyl, pyridyl and the like. The term zwitterionic group as used herein refers to a moiety including both one or more positively (cationic) and negatively (anionic) charged groups in the same moiety. Typically, the charges on the positively and negatively charged groups are balanced, resulting in a moiety with zero net charge. However, it is not necessary that the charges on the cationic and anionic groups balance out. Particular zwitterionic groups that may be mentioned include, but not limited to amino acid groups , betaine groups, and groups of the following formulae: , , , . As provided herein, represents a point of attachment to the compound of formula I. Unless otherwise specified, the term PEG group refers to a moiety comprising a polyethylene glycol (i.e. ) residue, wherein z is, for example, 2 to 10. The term “linking group”, as used herein, refers to any group which is suitable for connecting the solubilising group(s) and / or the group capable of being conjugated to a biomarker and / or biomolecule to the portion of the compound of the invention. For example, a linking group links group R1to group A in the compound of formula I. In particular embodiments, a “linking group” comprises a series of 1 to 100 (for example, 1 to 50, such as 1 to 20, preferably, 1 to 10) connected linker moieties. In some embodiments, linker moieties are straight or branched chains comprising any combination of alkyl, or alkenyl chains or aromatic groups, and main-chain heteroatoms (e.g., O, S, N, P, etc.), which alkyl and alkenyl chains or aromatic groups are optionally substituted by one or more (e.g.1, 2 or 3) substituents independently selected from the group consisting of, as appropriate, -OH, =O, -C(O)OH, -C(O)O(C1-4alkyl), -NH2, =NH, -C(O)NH, -C(O)N(C1-4 alkyl), -SH, -C(S)(C1-4 alkyl), -S(O)2NH2, and -S(O)2(C1-4 alkyl). For example, each linker moiety may be independently selected from the group consisting of C1-4alkylene (e.g. -CH2-), C2-4alkenylene (e.g. -CH=CH-), -C(OH)H-, -C(NH2)H-, -O-, -C(O)-, -NH-, -S-, -S(O)-, -S(O)2-, and . Particular linking groups that may be mentioned include -(CH2)-, -(CH2)-O-(CH2)-, -(CH2)3-O-(CH2)-, -O-(CH2)2-O-, and -O-C(O)-NH-. The skilled person will understand that a group capable of being conjugated to a biomarker and / or biomolecule is a group capable of forming a covalent bond between the compound and the biomarker and / or biomolecule. For example, a covalent bond (e.g. an amide bond) may be formed by a reaction between e.g. a carboxylic acid (i.e. -CO2H) moiety present on a compound of the invention as hereinbefore defined, and an amine (i.e. -NH2) group that is present in the biomarker and / or biomolecule. Particular groups capable of being conjugated to a biomarker and / or biomolecule include, but are not limited to): carboxylic acids and derivatives thereof (e.g. -C(O)OR5and -C(O)Cl, wherein R5is as defined herein); isocyanate (i.e. -NCO); isothiocyanate (i.e. -NCS); thiol (i.e. -SH); a thioester (i.e. -C(O)SR6, wherein R6is as defined herein)); a maleimidyl group (e.g. an iodoacetamidyl group By “biomarker and / or biomolecule” we include the meaning of a naturally-occurring biological molecule, or component or fragment thereof, the measurement of which can provide information useful in the prognosis and / or diagnosis of a disease or disorder. For example, the biomarker may be a naturally-occurring protein or carbohydrate moiety, or an antigenic component or fragment thereof. For example, in particular embodiments, the biomarker and / or biomolecule is selected from the group consisting of an antigen, an antibody, a peptide, a protein, a nucleic acid, a vesicle, or a carbohydrate. Particular biomarker and biomolecules that may be mentioned are those containing a lysine residue. For the avoidance of doubt, in cases in which the identity of two or more substituents in a compound of formula I may be the same, the actual identities of the respective substituents are not in any way interdependent. Where groups are referred to herein as being optionally substituted it is specifically contemplated that such optional substituents may be not present (i.e. references to such optional substituents may be removed), in which case the optionally substituted group may be referred to as being unsubstituted in certain embodiments. Throughout this specification, structures may or may not be presented with chemical names. Where any question arises as to nomenclature, the structure prevails. Where it is possible for the compound to exist as a tautomer (e.g. in an alternative resonance form) the depicted structure represents one of the possible tautomeric forms, wherein the actual tautomeric form(s) observed may vary depending on environmental factors such as solvent, temperature or pH. All tautomeric (and resonance) forms and mixtures thereof are included within the scope of the invention. Unless indicated otherwise, all technical and scientific terms used herein will have their common meaning as understood by one of ordinary skill in the art to which this invention pertains. For the avoidance of doubt, the skilled person will understand that references herein to particular aspects of the invention (such as the first aspect of the invention) will include references to all embodiments and particular features thereof, which embodiments and particular features may be taken in combination to form further embodiments and features of the invention. Preferably, A and B are each a phenyl group. Thus, particular compounds of the invention that may be mentioned include compounds of formula IA, wherein R1, R2, m and n are as defined herein. Compounds of the invention comprises one or more ‘solubilising groups’, i.e. groups which facilitated the dissolution of a compound of the invention in a suitable (e.g. aqueous) media. The water solubility of compounds of the invention allows for the synthesis of water-soluble Raman-tagged bioconjugates (e.g. antigen targeting molecules with distinct Raman tags), which enable the easy identification of biomolecules (e.g. peptides, proteins, and / or antibodies) in a complex, biological sample (e.g. cells, tissues, patient samples). More particularly, the improved water solubility of the compounds of the invention makes it possible to label a significantly high number of said compounds (i.e. Raman tags) on to biomarkers / biomolecules (e.g. peptides, proteins, antibodies etc.) thereby forming Raman active bioconjugates, allowing for the design and detection of biomakers / biomolecules with mutliplexable oligoyne derivatives of the compound of formula I. Particular ‘solubilising groups’ that may be mentioned include -S(O)2OH, -S(O)OH, -OS(O)2OH, -S(O)2NH2, -P(O)(OH)2, -OP(O)(OH)2, phosphonium salts (e.g. -P+(R3)3), quaternary ammonium salts (e.g. -N+(R3)3), -OH, -C(O)OH, -NHC(O)OH, 5- or 6-membered heterocyclylalkyl groups, a 5- or 6-membered heteroaryl groups, zwitterionic groups, and PEG groups, as defined herein. Thus, in particular embodiments, R1is selected from the group consisting of -S(O)2OH, -P(O)(OH)2, and -N+(R3)3. Preferably, R1is -S(O)2OH. As indicated herein L1is a bond or a suitable linking group. In this context, suitable linking groups include 1 to 50 (for example, 1 to 20, such as 1 to 10) connected linker moieties each independently selected from the group consisting of C1-4 alkylene (e.g. -CH2-), C2-4 alkenylene In particular embodiments L1is -(CH2)-. Preferably, L1is a bond. As indicated here, compounds of the invention possess at least one (e.g. 1, 2 or 3) solubilising (i.e. R1) group. In particular embodiments, compounds of the invention possess one R1group (i.e. m is 1). Accordingly, particular compounds of the invention that may be mentioned include compounds of formula IB, wherein R1, R2and n are as defined herein. In particular embodiments, R1and R2are different. Thus, particular compounds of the invention that may be mentioned are compounds of formula I (including all embodiments and particular features, and combinations thereof) provided that R1and R2are different (i.e. not the same). The compounds of the invention comprise a group capable of being conjugated to a biomarker and / or biomolecule. Said group may be bonded directly to group B. Alternatively, said group may be connected to group B by a suitable linker. Thus, in particular embodiments, R2is a group, wherein L2is a bond or a suitable linking group; R4is selected from the group consisting of -C(O)OR5, -C(O)Cl, -NCO, -NCS, group, which C1-4 alkyl group is optionally substituted with one or more phenyl groups; and R6is selected from the group consisting of hydrogen and a C1-4 alkyl group. In particular embodiments, R4is selected from the group consisting of -C(O)OR5, R5is selected from the group consisting Preferably, R4a -C(O)OR5group as defined herein, such as, -C(O)OH. As indicated herein L2is a bond or a suitable linking group. In this context, suitable linking groups include 1 to 30 (for example, 1 to 10, such as 1 to 5, preferably, 1) connected linker moieties each independently selected from the group consisting of C1-4alkylene (e.g. -CH2-), C2-4alkenylene (e.g. -CH=CH-), -O-, -C(O)-, -NH-, -S-, -S(O)-, -S(O)2-, and Thus, in particular embodiments, R4is -C(O)OR5; and L2is a bond Particular embodiments of the invention that may be mentioned are those wherein R4is - C(O)OH and L2is a bond. Thus, preferred compounds of the invention are those wherein R2is -C(O)OH. Accordingly, in further embodiments, particular compounds of the invention that may be mentioned include compounds of formula IC, wherein n is as defined herein. Compounds of the invention comprise 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 alkyne moieties and may therefore be referred to as polyynes. Preferably, compounds of the invention comprise 2, 3, or 4 alkyne moieties; for example, 2, or 3 alkyne moieties (i.e. n is 2 or 3). Particularly preferred compounds of the invention (or salts or solvates thereof) are depicted in Table 1, below. Example Compound Name Compound Structure No. 1 4-((2-sulfophenyl)buta-1,3- HO O S diyn-1-yl)benzoic acid HO O O 2 4-((3-sulfophenyl)buta-1,3-OOHS diyn-1-yl)benzoic acid HO O O 3 4-((4-sulfophenyl)buta-1,3- HO O diyn-1-yl)benzoic acidS OH O O 4 4-((3-sulfophenyl)hexa-OOHS 1,3,5-triyn-1-yl)benzoic acid HO O O Table 1. Preparation Compounds of the invention as described herein may be prepared in accordance with techniques that are well known to those skilled in the art, such as those described in the examples provided hereinafter. Compounds of formula I may be obtained by analogy with the processes known in the literature, or by conventional synthetic procedures, in accordance with standard techniques, from available starting materials using appropriate reagents and reaction conditions. In this respect, the skilled person may refer to inter alia “Comprehensive Organic Synthesis” by B. M. Trost and I. Fleming, Pergamon Press, 1991. According to a second aspect of the invention, there is provided a process for preparing a compound as defined in the first aspect of the invention (i.e. a compound of formula I), which process comprises reacting a protected derivative of a compound of formula I in the presence of a suitable deprotecting agent. For example, for compounds of formula I where R1is –S(O)2OH and R2is -C(O)OH (i.e. compounds of formula IC as defined herein) may be prepared by reacting a compound of formula II wherein n is as defined herein and P1is a suitable sulfonic acid protecting group (such as a 2,2,2-trifluoro-1-(p-tolyl)ethyl group) and P2is a suitable carboxylic acid protecting group (such as a tert-butyl group), with a suitable deprotecting agent (e.g. trifluoroacetic acid) in the presence of a suitable solvent (e.g. dichloromethane) according to procedures know to the person skilled in the art. The compound of formula II may be prepared by reaction of a compound of formula III, with a compound of formula IV, wherein P1and P2are as defined hereinabove, X is a suitable halide atom (such as a bromine atom) and q is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11, in the presence of a copper(I) salt (e.g. CuCl), a suitable reducing reagent (hydroxylamine hydrochloride) and a suitable solvent (e.g. diethyl ether) according to procedures know to the person skilled in the art. Compounds of formula III may be commercially available, known in the literature, or may be obtained by conventional synthetic procedures, in accordance with standard techniques, from available starting materials using appropriate reagents and reaction conditions. For example, the compound of formula III may be prepared by reaction of a compound of formula V, wherein P2and q are as defined hereinabove, with a suitable halogenating agent (e.g. N- bromosuccinimide) and a suitable deprotecting / activating agent (e.g. silver(I) fluoride) in the presence of a suitable solvent (e.g. acetonitrile) according to procedures know to the person skilled in the art. Compounds of formula V may be commercially available, known in the literature, or may be obtained by conventional synthetic procedures, in accordance with standard techniques, from available starting materials using appropriate reagents and reaction conditions. Compounds of formula IV may be commercially available, known in the literature, or may be obtained by conventional synthetic procedures, in accordance with standard techniques, from available starting materials using appropriate reagents and reaction conditions. For example, the compound of formula IV may be prepared by reaction of a compound of formula VI, wherein P1is as defined hereinabove, with a suitable deprotecting agent (e.g. TBAF) in the presence of a suitable solvent (e.g. THF) according to procedures know to the person skilled in the art. Compounds of formula VI may be commercially available, known in the literature, or may be obtained by conventional synthetic procedures, in accordance with standard techniques, from available starting materials using appropriate reagents and reaction conditions. For example, the compound of formula VI may be prepared by reaction of a compound of formula VII, with a compound of formula VIII, wherein P1is defined hereinabove and X is a suitable halide atom (such as a bromine atom), in the presence of a suitable coupling agent (e.g. bis(triphenylphosphine)palladium(II) dichloride), a suitable copper(I) salt (e.g. CuI), a suitable ligand (e.g. triphenylphosphine), a suitable base (e.g. N,N-diisopropylamine), and a suitable solvent (e.g. toluene) according to procedures know to the person skilled in the art. Compounds of formula VII may be commercially available, known in the literature, or may be obtained by conventional synthetic procedures, in accordance with standard techniques, from available starting materials using appropriate reagents and reaction conditions. For example, the compound of formula VII may be prepared by reaction of a compound of formula IX, wherein X is as defined hereinabove and Z is a suitable leaving group (e.g. a chloride atom), with a suitable protecting agent (e.g. 2,2,2-trifluoro-1-(p-tolyl)ethan-1-ol) in the presence of a suitable base (e.g. 1,4-diazabicyclo(2.2.2)octane), and a suitable solvent (e.g. CH2Cl2) according to procedures know to the person skilled in the art. Compounds of formula VIII and formula IX may be commercially available, known in the literature, or may be obtained by conventional synthetic procedures, in accordance with standard techniques, from available starting materials using appropriate reagents and reaction conditions. Uses It has been found that compounds of the invention display a strong Raman signal in the Raman silent region (1800 – 2800 cm-1), which is unperturbed by a biological sample, and therefore allows for the identification of a biomolecule of interest within the sample. Accordingly, the compounds of the invention may be considered as being ‘Raman tags’ or ‘Raman labels’. In addition, it has been found that compounds of the invention have higher Raman signals when compared with other Raman active molecules (e.g. alkynes, azides, per-deuterated compounds, or nitriles), which display signals in the Raman silent region but with a far lower relative intensity compared to the compounds of the invention. Thus, one use of the compounds of the invention lies in their ability to form Raman-tagged bioconjugate with biomarkers and / or biomolecules. More specifically, compounds of the invention are useful because their water solubility allows for the formation of water-soluble Raman-tagged bioconjugates, which exhibit high signal-to-noise ratio in the Raman silent region. Accordingly, such bioconjugates can be used as highly sensitive tag molecules in Raman spectroscopy of biological systems thereby enabling the easy identification of biomolecules (e.g. peptides, proteins, and / or antibodies) in a complex, biological sample (e.g. cells, tissues, patient samples). Previously reported compounds based on oligoyne structures show reduced solubility in aqueous environments as a result of their carbon backbone, which limits their application as vibrational tags for biomolecule detection since conjugation of these compounds causes biomolecule instability in aqueous media. The Raman signal of the Raman-tagged bioconjugates can be synthesised with multiplexable signals, allowing for the identification of multiple bioconjugates, simultaneously by tuning the number of alkyne units within the structure. Unlike alkyne derivatives previously reported, the water solubility of the compounds of the invention makes it possible to label a significantly high number of compounds on to biomarkers and / or biomolecules of interest (e.g. peptides, proteins, antibodies etc.) to provide water- soluble Raman active bioconjugates, allowing for improved multiplexing of all oligoyne derivatives. The data present in the examples show that bioconjugation experiments of non-water- soluble derivatives displayed 0.31 tags per antibody. However, with compounds of the invention, at least greater than 6 tags per antibody may be achieved. The enhanced efficiency of tagging allows the signal to be readily detected on biomolecules reducing their limit of detection. According to a third aspect of the invention, there is provided a Raman-tagged bioconjugate formed from a compound of formula I as defined herein and a biomarker and / or biomolecule. These bioconjugate compounds, including salts and solvates thereof, may be referred to herein as the “bioconjugates of the invention”. Bioconjugates of the invention may feature at least one covalent bond (e.g. an amide bond) formed by a reaction between a carboxylic acid (i.e. -CO2H) moiety present on a compound of formula I as hereinbefore defined (e.g. at R2), and an amine (i.e. -NH2) group that is present in the biomarker and / or biomolecule. Particular biomarkers and / or biomolecules that may be mentioned are selected from the group consisting of an antigen, an antibody, a peptide, a protein, a nucleic acid (e.g. RNA, DNA, etc.), a vesicle and a carbohydrate. For example specific extracellular markers such as CD63, or cancer specific markers such as: HER2, LIV-1 EGFR, TROP2 and EpCAM. The skilled person will recognise that the compounds of the invention may be used to prepare the bioconjugates of the invention as defined herein (i.e. the Raman-tagged bioconjugates of the third aspect of the invention). Therefore, in a fourth aspect of the invention, there is provided the use of a compound of formula I as defined herein in the preparation of a Raman-tagged bioconjugate as defined herein. As indicated herein, the bioconjugates of the invention comprise a biomarker and / or biomolecule. Said biomarker and / or biomolecule may possess pharmacological activity, and / or may be metabolised in the body following oral or parenteral administration to form a compound that possesses pharmacological activity. Accordingly, bioconjugates of the invention may also possess said pharmacological activity. Thus, according to a fifth aspect of the invention there is provided a Raman-tagged bioconjugate, as hereinbefore defined (i.e. a Raman-tagged bioconjugate as defined in the third aspect of the invention) for use in medicine. The bioconjugates of the invention are particularly useful for detecting the presence or absence of a biomarker and / or biomolecule in a sample using Raman spectroscopy. According to a sixth aspect of the invention there is provided a method of detecting the presence or absence of a biomarker and / or biomolecule in a sample, wherein the method comprises the steps of: a) providing a sample; b) incubating said sample with a compound of formula I as defined herein under conditions that allow formation of a Raman-tagged bioconjugate as defined herein, wherein the Raman-tagged bioconjugate is formed if the biomarker and / or biomolecule is present in the sample; c) removing any non-conjugated compound of formula I; and, d) analysing the sample using Raman spectroscopy to detect the presence or absence of the Raman-tagged bioconjugate. Preferably the method is an in vitro or ex vivo method. It will be appreciated that non-conjugated compound of formula I refers to any compound of formula I that has not formed a conjugate following incubation with the sample. It will also be appreciated that by ‘removing any non-conjugated compound of formula I’ in step (c) we mean removing at least about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 100% of non-conjugated compound of formula I. The term “about” as used herein when referring to a measurable value such as an amount of a compound, dose, time, temperature, and the like, refers to variations of 20%, 10%, 5%, 1%, 0.5%, or even 0.1% of the specified amount. It is contemplated that, at each instance, such terms may be replaced with the notation “±10%”, or the like (or by indicating a variance of a specific amount calculated based on the relevant value). It is also contemplated that, at each instance, such terms may be deleted. Any Raman spectroscopic technique can in principle be used to determine the presence and / or absence of the Raman-tagged bioconjugate in the sample. For example, spontaneous Raman spectroscopy, enhanced Raman spectroscopy (e.g. surface enhanced Raman spectroscopy, tip enhanced Raman spectroscopy, surface plasmon polariton enhanced Raman scattering, surface enhanced resonance Raman spectroscopy), non- linear Raman spectroscopy, non-resonance Raman spectroscopy, resonance Raman spectroscopy, confocal Raman spectroscopy, coherent anti-stokes Raman spectroscopy, spatially offset Raman spectroscopy, deep Raman spectroscopy, and morphologically- directed Raman spectroscopy. Where applicable, any of these techniques may be combined with techniques for sample trapping, such as spontaneous Raman spectroscopy coupled with optical tweezers. Preferably, detecting the presence and / or absence of the biomarkers in step (d) may be determined by the detection of a signal in the Raman silent region (1800 – 2800 cm-1), said signal being associated with, and indicative of, a compound of the invention. Thus, in particular embodiments, the presence of a biomarker is indicated by a Raman signal, as defined by the user, in the Raman silent region greater than that of a negative control containing only the biomarker to be measured. In other embodiments, the absence of a biomarker is indicated by a Raman signal which is indistinguishable from a Raman signal of a blank buffer sample in the Raman silent region. As defined herein, a sample is an item that is to be the subject to analysis (by, for example, Raman spectroscopy). In the context of the present invention the term sample encompasses items comprising, including, containing, featuring (or similar) biomolecules, bioparticles, and biological material or systems at the single particle level (where the expression ‘particles’ in the context of this disclosure encompasses micro- and nano- particles and other objects capable of exhibiting a Raman response, e.g., polymer particles and vesicles for drug delivery systems, such as liposomes and polymersomes, as well as extra-cellular vesicles or exosomes). Suitable samples that may be mentioned include biological samples, chemical samples (e.g. non-aqueous solutions, suspensions, colloids, emulsions and foams), water samples (e.g. aqueous solutions, suspensions, colloids, emulsions and foams), food samples, environmental samples (e.g. water, soil, biological material, and waste (liquids, solids or sludges) samples collected from an environment) and process (including bioprocess) samples. Preferably the sample is a biological sample. Preferably the biological sample is provided from a mammal. The mammal may be any domestic or farm animal (e.g. a rat, mouse, guinea pig, cat, dog, horse or a primate). Preferably, the mammal is human. A biological sample as used herein includes any relevant biological sample that can be used for molecular profiling, e.g., sections of tissues such as biopsy or tissue removed during surgical or other procedures, bodily fluids (e.g. liquid biopsy), autopsy samples, and frozen sections taken for histological purposes, a sample comprising cells. Such biological samples include blood or blood fractions or products (e.g. serum, buffy coat, plasma, platelets, red blood cells, and the like), sputum, malignant effusion, cheek cells tissue, cultured cells (e.g., primary cultures, explants, and transformed cells), stool, urine, other biological or bodily fluids (e.g., prostatic fluid, gastric fluid, intestinal fluid, renal fluid, lung fluid, cerebrospinal fluid, and the like), etc. The biological sample can comprise biological material that is a fresh frozen & formalin fixed paraffin embedded (FFPE) block, FFPE, or is within an RNA preservative and formalin fixative. Preferably the biological sample is a cell or tissue sample (or derivative thereof), for example one comprising or consisting of cancer cells. A biological sample may be processed according to techniques understood by those skilled in the art. A sample can, without limitation, be fresh, frozen or fixed cells or tissue. A biological sample can comprise cultured cells, including primary or immortalized cell lines derived from a sample from a subject. A biological sample can also refer to an extract from a sample from a subject. For example, a biological sample can comprise DNA, RNA or protein extracted from a tissue or a bodily fluid. Many techniques and commercial kits are available for such purposes. The fresh biological sample from the subject can be treated with an agent to preserve RNA prior to further processing, e.g., cell lysis and extraction. Biological samples can include frozen samples collected for other purposes. Biological samples can be associated with relevant information such as age, gender, and clinical symptoms present in the subject; source of the sample; and methods of collection and storage of the sample. Detection of the presence or absence of a biomarker and / or biomolecule in a sample may be broadly applicable, but limited, to the monitoring of water, food and environmental contaminants, bioprocessing reactions, drug doping, drug overdosing, therapeutic drugs in patients, and exposure to environmental toxins. Detection of the presence or absence of a biomarker and / or biomolecule in a biological sample may be particularly useful for diagnosing a disease or disorder in a subject. According to a seventh aspect of the invention, there is provided a method of diagnosing a disease or disorder in a subject, wherein the method comprises the steps of: a) providing a biological sample previously obtained from a subject; b) incubating said biological sample with a compound of formula I as defined herein under conditions that allow formation of a Raman-tagged bioconjugate as defined herein, wherein the Raman-tagged bioconjugate is formed if the biomarker and / or biomolecule is present in the biological sample; c) removing any non-conjugated compound of formula I; and, d) analysing the biological sample using Raman spectroscopy to detect the presence or absence of the Raman-tagged bioconjugate, wherein detection of the presence of the Raman-tagged bioconjugate indicates that the subject has the disease or disorder. In particular embodiments, the disease or disorder is selected from the group consisting of cancer, cardiovascular disease (such as heart failure), diabetic kidney disease, diabetes (such as type 2 diabetes), insulin resistance, non-alcoholic fatty liver disease, non- alcoholic steatohepatitis, pain, obesity, inflammation (including chronic inflammatory diseases), autoimmune diseases, osteoporosis, intestinal diseases and hyperinsulinemia associated with obesity or cardiovascular disease, hyperinsulinemia and associated conditions, a condition / disorder where fibrosis plays a role, and neurodegenerative diseases. The term “cancer”' will be understood by those skilled in the art to include one or more diseases in the class of disorders that is characterized by uncontrolled division of cells and the ability of these cells to invade other tissues, either by direct growth into adjacent tissue through invasion, proliferation or by implantation into distant sites by metastasis. By “proliferation” we include an increase in the number and / or size of cancer cells. By “metastasis” we mean the movement or migration (e.g. invasiveness) of cancer cells from a primary tumor site in the body of a subject to one or more other areas within the subject's body (where the cells can then form secondary tumors). Thus, the method of the seventh aspect of the invention may be suitable for diagnosing any cancer type, including all tumors (non-solid and, preferably, solid tumors, such as carcinoma, adenoma, adenocarcinoma, blood cancer, irrespective of the organ). For example, the cancer cells may be selected from the group consisting of cancer cells of the breast, bile duct, brain, colon, stomach, reproductive organs, thyroid, hematopoietic system, lung and airways, skin, gallbladder, liver, nasopharynx, nerve cells, kidney, prostate, lymph glands and gastrointestinal tract. Preferably, the cancer is selected from the group consisting of colon cancer (including colorectal adenomas), breast cancer (e.g. postmenopausal breast cancer), endometrial cancer, cancers of the hematopoietic system (e.g. leukemia, lymphoma, etc.), thyroid cancer, kidney cancer, oesophageal adenocarcinoma, ovarian cancer, prostate cancer, pancreatic cancer, gallbladder cancer, liver cancer and cervical cancer. More preferably, the cancer is selected from the group consisting of colon, prostate and, particularly, breast cancer. Where the cancer is a non- solid tumor, it is preferably a hematopoietic tumor such as a leukemia (e.g. Acute Myelogenous Leukemia (AML), Chronic Myelogenous Leukemia (CML), Acute Lymphocytic Leukemia (ALL), or Chronic Lymphocytic Leukemia (CLL). Preferably the cancer cells are breast cancer cells. The term “diabetes” (i.e. diabetes mellitus) will be understood by those skilled in the art to refer to both type 1 (insulin-dependent) diabetes and type 2 (insulin-independent) diabetes, both of which involve the malfunction of glucose homeostasis. The method of the seventh aspect of the invention may be suitable for diagnosing type 1 diabetes and / or type 2 diabetes. As well as being useful in diagnosing diabetes, the method of the seventh aspect of the invention may also be suitable for diagnosing diabetic kidney disease (i.e. diabetic nephropathy). “Diabetic kidney disease” refers to kidney damage caused by diabetes and is a serious complication of type 1 diabetes and type 2 diabetes. Diabetic kidney disease affects the kidneys' ability to remove waste products from blood to be excreted as urine, and can lead to kidney failure. Moreover, the method of the seventh aspect of the invention may be suitable for diagnosing chronic kidney disease, including chronic kidney disease in the absence of type 2 diabetes. “Chronic kidney disease” is a condition characterised by a gradual loss of kidney function over time. Chronic kidney disease usually occurs as a result of one or more other diseases or conditions that affect the kidneys, such as high blood pressure, diabetes, high cholesterol, kidney infections, glomerulonephritis, polycystic kidney disease, obstruction of the urinary tract blockages in the flow of urine and long-term medication use. The term “hyperinsulinemia or an associated condition” will be understood by those skilled in the art to include hyperinsulinemia, type 2 diabetes, glucose intolerance, insulin resistance, metabolic syndrome, dyslipidemia, hyperinsulinism in childhood, hypercholesterolemia, high blood pressure, obesity, fatty liver conditions, diabetic nephropathy, diabetic neuropathy, diabetic retinopathy, cardiovascular disease, atherosclerosis, cerebrovascular conditions such as stroke, systemic lupus erythematosus, neurodegenerative diseases such as Alzheimer’s disease, and polycystic ovary syndrome. Other disease states include progressive renal disease such as chronic renal failure. In particular, the method of the seventh aspect of the invention may be suitable for diagnosing obesity associated with hyperinsulinemia and / or cardiovascular disease associated with hyperinsulinemia. The method of the seventh aspect of the invention may also be suitable for diagnosing cardiovascular disease, such as heart failure, wherein said cardiovascular disease is not associated with hyperinsulinemia. A condition / disorder where fibrosis plays a role includes (but is not limited to) scar healing, keloids, scleroderma, pulmonary fibrosis (including idiopathic pulmonary fibrosis), nephrogenic systemic fibrosis, and cardiovascular fibrosis (including endomyocardial fibrosis), systemic sclerosis, liver cirrhosis, eye macular degeneration, retinal and vitreal retinopathy, Crohn’s / inflammatory bowel disease, post-surgical scar tissue formation, radiation and chemotherapeutic-drug induced fibrosis, and cardiovascular fibrosis. Neurodegenerative diseases that may be mentioned include Alzheimer´s disease, Parkinson´s disease, Huntington´s disease, amyotrophic lateral sclerosis, polyglutamine disorders, such as spinal and bulbar muscular atrophy (SBMA), dentatorubral and pallidoluysian atrophy (DRPLA), and a number of spinocerebellar ataxias (SCA). The method of the seventh aspect of the invention may be suitable for diagnosing a non- alcoholic fatty liver disease (NAFLD). NAFLD is defined by excessive fat accumulation in the form of triglycerides (steatosis) in the liver (designated as an accumulation of greater than 5% of hepatocytes histologically). It is the most common liver disorder in developed countries (for example, affecting around 30% of US adults) and most patients are asymptomatic. If left untreated, the condition may progressively worsen and may ultimately lead to cirrhosis of the liver. NAFLD is particularly prevalent in obese patients, with around 80% thought to have the disease. NAFLD may be diagnosed wherein alcohol consumption of the patient is not considered to be a main causative factor. A typical threshold for diagnosing a fatty liver disease as “not alcohol related” is a daily alcohol consumption of less than 20 g for female subjects and less than 30 g for male subjects. Particular diseases or conditions that are associated with NAFLD include metabolic conditions such as diabetes, hypertension, obesity, dyslipidemia, abetalipoproteinemia, glycogen storage diseases, Weber–Christian disease, acute fatty liver of pregnancy, and lipodystrophy. Other non-alcohol related factors related to fatty liver diseases include malnutrition, total parenteral nutrition, severe weight loss, refeeding syndrome, jejunoileal bypass, gastric bypass, polycystic ovary syndrome and diverticulosis. Non-alcoholic steatohepatitis (NASH) is the most aggressive form of NAFLD, and is a condition in which excessive fat accumulation (steatosis) is accompanied by inflammation of the liver. If advanced, NASH can lead to the development of scar tissue in the liver (fibrosis) and, eventually, cirrhosis. Particular autoimmune diseases known to those skilled in the art include Crohn’s / inflammatory bowel disease, systemic lupus erythematosus and type 1 diabetes. Particular intestinal diseases that should be mentioned include Crohn’s / inflammatory bowel disease and cancer of gastrointestinal tract. The skilled person will understand that references to the “diagnosis” of a particular condition (or, similarly, to “diagnosing” that condition) will take their normal meanings in the field of medicine. In particular, the terms may refer to determining the presence or absence of a disease state in an individual (e.g., determining whether an individual is or is not suffering from a cancer). The skilled person will understand that such diagnosis will be performed in a subject in need thereof. The need of a subject for such diagnosis may be assessed by those skilled in the art using routine techniques. In the context of the present invention, a “subject in need” of diagnosis includes a subject that is suspected of suffering a disorder or disorder as defined herein. As used herein, the terms “disease” and “disorder” (and, similarly, the terms condition, illness, medical problem, and the like) may be used interchangeably. The skilled person will be aware that Raman spectroscopy is a useful technique for imaging a biological sample. For example, Raman scattering-based vibrational microscopy has been considered one of the most promising and powerful cell imaging tools in recent years, enabling, amongst other things, direct visualization of detailed molecular structure information, quantitative relationship between signal intensity and substance concentration, and narrow-band multi-colour imaging. As indicated therein, the compounds of the invention are useful for preparing Raman tagged bioconjugates (e.g. bioconjugates of the third aspect of the invention). Said Raman tagged bioconjugates may be detectable using Raman spectroscopy thereby facilitating imaging of a biological sample. According to an eighth aspect of the invention, there is provided an in vitro or ex vivo method of imaging a biological sample, wherein the method comprises the steps of: a) providing a biological sample; b) incubating a compound of formula I as defined herein with the biological sample so as to form a Raman-tagged bioconjugate as defined herein, wherein the Raman-tagged bioconjugate is formed if the biomarker and / or biomolecule is present in the biological sample; c) removing any non-conjugated compound of formula I; and d) imaging the biological sample using Raman spectroscopy. The method(s) disclosed in the present specification is / are suitable for detecting / imaging any Raman-tagged bioconjugate as defined herein (e.g. according to the third aspect of the invention). As provided herein, compounds of the invention (such as compounds of formula I) may be provided in the form of a kit together with instructions for using the compound of formula I in, for example, a method as described herein. Thus, according to a nineth aspect of the invention, there is provided a kit of parts comprising: (a) a compound of formula I as defined herein; and (b) instructions for using the compound of formula I as defined herein in an in vitro or ex vivo method of detecting the presence or absence of a biomarker and / or biomolecule in a sample, a method of diagnosing a disease or disorder in a subject and / or a method of imaging a biological sample. In a particular embodiment, the instructions relate to the in vitro or ex vivo method of detecting the presence or absence of a biomarker and / or biomolecule in a biological sample, the method of diagnosing a disease or disorder in a subject and / or the method of imaging a biological sample as defined herein. Without wishing to be bound by theory, it is thought that the compounds of the invention display enhanced solubility which enables efficient tagging to biomarkers and / or biomolecules thereby providing water-soluble bioconjugates. The water solubility of the bioconjugates reduces their limit of detection and allows for enhanced detection of biomarkers and / or biomolecules in biological samples by Raman spectroscopy. This enhanced detection of biomarkers and / or biomolecules may be particularly useful in methods of detecting, imaging, and diagnosis involving Raman spectroscopy. According to another aspect, the invention provides a computer program, distributable by electronic data transmission or by computer readable medium, comprising computer program code means adapted, when said program is loaded onto an automated particle capture system, to make the automated particle capture system execute any of the data acquisition procedures described herein. Illustrated Examples The present invention is explained in greater detail in the following non-limiting examples. Figure 1 shows spontaneous normalised Raman spectra 100 of the sulfonated oligoynes, according to an example. The different oligoyne (2-yne to 4-yne) derivatives (Example 1, 4 and 5) show EDVHOLQH^ VHSDUDWHG^ 5DPDQ^ VSHFWUD^ EDVHG^ RQ^ WKHLU^ V\PPHWULFDO^ &ʵ&^ stretching frequency. As additional alkyne uniWV^DUH^DGGHG^^WKH^V\PPHWULFDO^&ʵ&^PRYHV^ to a lower wavenumber due to an increase in the conjugation length of the alkyne bonds, the conjugated ^-bonds being lower in energy. Raman spectra of the protected derivative in the case of the 4-yne (Example 5 precursor). Figure 2 shows a representative example using Raman spectroscopy for detection of HEK293F extracellular vesicles (EVs) and HEK293F CD63 overexpressing EVs. The Raman spectra 200 were collected using the SPARTA®system referenced and described below and show that HEK293F EVs and HEK293F CD63 overexpressing EVs show no Raman signals in the Raman silent region (1800-2800 cm-1). An antibody which recognises CD63 was conjugated with a sulfonated oligoyne (Example 2) allowing for detection of the CD63 protein on the EVs in a dose dependent manner (as seen particularly in the inset Raman data 200a) with either 100 or 1000 molar equivalents of Raman-tagged antibody (RAb) relative to the EV concentration. Figure 3 shows UV-Vis spectra 300 of Raman-tagged bioconjugates, according to an example. The UV-vis spectra 300 confirm that successful bio-conjugation has occurred, as can be seen from the increase in relative absorbance at 345 nm (compared with the bioconjugate (CD63 / IgG) absorbance at 280 nm) due to the presence of the Raman tag. By varying the Raman tag degree of functionalisation on the bioconjugate, the UV-Vis data permits calculation of the extinction co-efficient of the Raman tag, which in this example was calculated to be 16,747 cm-1M-1using the peak at 345 nm. The IgG antibody extinction co-efficient is 210,000 cm-1M-1using the peak at 280 nm. The ratio of the extinction coefficient at 345 nm to the extinction coefficient at 280 nm is 0.834, which is used as a correction factor in these concentration calculations to account for the contribution of the tag at 280 nm. Figure 4 shows a representative molecular weight trace 400 from an Agilent 2100 Bioanalyzer of successful Herceptin bio-conjugation, according to an example. In this trace 400 the relative molecular weight of the IgG antibody (with 7 tags bio-conjugated to the surface) highlighted with a black arrow 401. IgG antibodies have a relative molecular weight of 150 kDa which can be observed on the molecular weight trace obtained from this technique (n.b., the position of the 150 kDa peak in the representative molecular weight trace is due to calibration of the molecular weights of the samples). Observing this peak, and no other larger peaks in the trace 400 around 150 kDa, alongside the example UV-Vis traces of the Raman tag shown in Figure 3, confirm that successful bio-conjugation has occurred. Single Particle Automated Trapping Analysis (SPARTA®) As introduced above, a utilisation of the compounds disclosed herein is in conjunction with the Single Particle Automated Trapping Analysis (SPARTA®) system described in international patent application no. PCT / EP2019 / 066106, published as WO 2019 / 243375 A1, and Penders, J., Pence, I.J., Horgan, C. et al. Single Particle Automated Raman Trapping Analysis. Nat Commun 9, 4256 (2018). Typical approaches to detect specific biomolecules on single particles are subject to two challenges: 1) for a given sample, ensuring that the information obtained from single particles is representative of the sample bulk; and 2) being able to detect specific biomolecules on single particles. SPARTA®can overcome the first challenge; however, it is not able to detect specific biomolecules. Other imaging techniques such as immunostaining combined with super resolution microscopy techniques can address the second challenge, however, these are limited by the ability to measure enough particles to demonstrate that the measurements made are representative of the bulk sample. The second challenge outlined above can be overcome by combining SPARTA®with the synthesised water-soluble Raman active tagging molecules (Raman tags) described herein. This is carried out by bio-conjugation of the Raman tags to label antibodies of interest, as discussed above, the resultant Raman active antibodies (Ramanbodies) used to label particles which can then be detected using SPARTA®. The improved water solubility of these tags advantageously facilitates an increased Raman signal compared with poly-yne derivatives which have not been modified with water-solubilising groups or other Raman active compounds and so enables detection via SPARTA®. Figure 5 shows in schematic form an overview of an example process 500 for biomolecule detection on single particles. According to this process, nanoparticles such as extracellular vesicles (EVs) are exemplary found in patient blood samples. In alternative examples the EVs may be sourced from other bodily fluids. Raman active markers are synthesised 502 to detect specific biomolecules of interest. In addition, multiple biomolecule markers can be detected simultaneously. When Raman active markers are mixed with the extracellular vesicles, a specific interaction between the biomolecule of interest and the Raman active marker occurs, labelling the particle with a unique Raman signal. The labelled EVs are analysed 503 (e.g., using SPARTA®) to detect the presence of the biomolecule of interest on a single particle basis. The following discussion covers pertinent aspects and example uses of the SPARTA®system in relation to the compounds and Raman-tagged bioconjugates described herein. The reader is nonetheless referred to the identified descriptions of the SPARTA®system for a comprehensive discussion thereof. Furthermore, these example uses are not intended to limit the detection and / or analysis of the compounds and Raman-tagged bioconjugates described herein by Raman techniques (both spectroscopic and imaging) more generally. In general, the SPARTA®system is configured to provide high throughput, routine size and / or composition analysis on a single particle basis without confounding contributions of substrates. More specifically, Raman spectroscopy is applied in combination with optical trapping, a process through which a particle can be levitated or trapped due to the radiation pressure created by a focused laser. Nanoparticles in the Rayleigh limit (r ا NJ^^ are trapped due to a difference in polarisability of the particle compared to the solution, leading to a dipole gradient force. This force scales with laser intensity and decreases with increasing distance from the focal volume, which directs the particle into the optical trap at the focal point of the laser. Figure 6 shows a schematic diagram of an automated particle capture system 600 for particle analysis, particularly applicable to Raman spectroscopic analysis, according to an example. The system 600 comprises a source 604 of electromagnetic radiation, which in this example is a light source and more preferably a laser. A dichromatic mirror 605 directs laser radiation 606 towards a sample 607 for analysis via a focusing element 608. Electromagnetic radiation 609 from the illuminated sample 607 is directed to a detector 610 via the dichromatic mirror 605. Elastically scattered radiation from the sample 607 at the wavelength of the laser beam is filtered out by a suitable filter (not shown) at the detector 610 and Raman scattered radiation passes to a detection device of the detector 610. A substrate 611 is provided to receive the sample 607 for analysis, which may be covered with a suitable cover 612, e.g. to limit evaporation of the sample. The cover 612, if used, is transparent to the electromagnetic radiation 606, 609. In another example, the cover may comprise the focusing element 608 which may be the objective lens of the system so that the sample may be in direct contact with the objective (e.g. water immersion). The sample 607 comprises any fluid medium 613 capable of conveying particles 614 for analysis therein. The expression 'capable of conveying' is intended to encompass any fluid medium 613 that is capable of providing suspension of the particles 614 within the medium whilst allowing movement or transport of the particles within, or by, the fluid medium 613 itself. For example, movement / transport of the particles 614 may be by diffusion within the medium 613 or may be by flow of the medium or a combination of both. In the example shown, where the volume of the sample 607 is generally static on the substrate 611 diffusion may be a primary mechanism for movement of the particles 614 relative to an impinging beam 606. In other arrangements, the substrate 611 may be configured for microfluidic control of the movement of fluid medium 613 and particles 614 suspended therein, e.g. using a microfluidic channel to move samples into position. Preferably, the fluid medium 613 is a liquid. The liquid may be a “non-opaque” or “non- heavily scattering” liquid such as water or a water-based buffer (e.g. phosphate buffered saline or 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid) possibly with the addition of low amounts of solvent (e.g. ethanol or dimethylsulfoxide). A control system 615 is coupled to the source of electromagnetic radiation (e.g., the laser) 604 and to the detector 610 to enable functionality that will be described below. Returning to the analysis step 503 shown in Figure 5, a focussed beam of electromagnetic radiation beam (e.g. from the source of electromagnetic radiation 604) passes through a medium in which particles are suspended. The beam has a waist portion 516 at its focus which defines a particle capture zone in which a particle 514a can be retained using an optical trapping effect, or single-beam gradient force trapping effect. The highly focused beam provides an attractive or repulsive force dependent on e.g. a refractive index mismatch to physically hold and move microscopic dielectric objects, such as the particles. For nanoparticles with diameters smaller than the wavelength of the trapping beam the mechanism may be understood as being based on dipole absorption and reradiation of the light. Figure 7 shows an example process 700 flow for automatic particle capture and data acquisition in accordance with the automated particle capture system of Figure 6. In a first step, an electromagnetic radiation beam is switched on and focused on the sample to define the particle capture zone at the beam waist (step 721). A Raman scattered radiation signal is detected at the detector in a first data acquisition procedure (step 722). At least a portion (e.g. a spectral portion) of this Raman signal is tested against a threshold to determine whether a particle has been captured or not (step 723). Further details can be found in WO 2019 / 243375 A1. If a particle is not detected from the Raman signal, and if particle capture has not failed more than a predetermined number of times (step 724), the process repeats to test the Raman signal against the threshold (step 722). There may be a short capture wait period (step 725) between successive ones of the first data acquisition procedure (step 721) to allow time for a particle to move into the particle capture zone by the prevailing transport mechanism, e.g. diffusion of the particles within the medium. If, at step 723, a particle is detected with the Raman signal, a second data acquisition procedure is effected (step 726). The second data acquisition procedure may also comprise detecting a Raman scattered radiation signal. Preferably, the second data acquisition procedure (step 726) comprises a much higher quality data signal acquisition procedure than the first data acquisition procedure (step 722). The higher quality data capture may comprise, for example, any one or more of: (i) an extended period of data capture to obtain a higher signal-to-noise ratio than that of the first data acquisition procedure, (ii) gathering of spectrally extended data, i.e. over a greater frequency bandwidth or selection of frequencies, (iii) collection of data using different modalities, e.g. modalities other than Raman spectroscopic signals; (iv) multiple periods of data capture for averaging; (v) altered laser power for increased signal to noise ratio; (vi) collection of data which is added to / combined with the data of the first data acquisition procedure to thereby improve the signal to noise ratio of the data from the first data acquisition procedure. Such other modalities could include, for example, fluorescence signals / spectra, absorption signals / spectra, and other optical spectroscopy techniques. The data acquired during the second data acquisition procedure 726 may be stored for later analysis with subsequently captured data sets, or may be processed / analysed on- the-fly in real time or pseudo-real time. After the second data acquisition procedure (step 726), the beam is disabled (step 727) to allow the captured particle to escape from the particle capture zone, during an escape wait period or escape delay period (step 728). In one arrangement, the first data acquisition procedure (step 722) comprises gathering Raman spectral data for a period of between 1 and 2 seconds and the second data acquisition procedure (step 726) comprises gathering Raman spectral data for a period of between 5 and 10 seconds. These times can be adjusted to optimise for various factors, e.g. the intensity of the Raman scattering of the particle due to composition or size, and the required signal to noise ratio of the resulting data or any other external constraints or requirements of the resulting data. More generally, the first data acquisition procedure (step 722) may comprise gathering Raman response signals to an extent (e.g. over an integration period) that is sufficient to enable detection of the presence of a particle by sensing its spectral profile above a threshold compared to a spectral profile that is obtained without a particle being present. The spectral profile may comprise an amplitude and / or shape of a peak or multiple peaks, an area under a peak or one or more peaks, an area under one or more portions of the Raman spectrum, a shape of at least a part of the spectrum, or some other feature. The process loop (steps 721-725) may repeat a predetermined number of times i (e.g. over a number of sampling periods), tested at step 724. The number of iterations permitted can be determined according to a number of factors, and a failure to detect a particle within the predetermined number of iterations (step 729) may trigger a restarting of the whole process or a recalibration process, to be described later. The disabling of the beam in step 727 may be effected by direct control of the laser, e.g. to power the laser on and off, or by shuttering or otherwise attenuating the beam. In this regard, particularly in step 727, it is noted that it may not be necessary to completely shut off the beam, only to reduce or attenuate the beam to a sub-capture level, i.e. an intensity level insufficient to retain a particle in the particle capture zone by the beam gradient force trapping effect. This might be effected by a modulation device (not shown), e.g. inserted into the beam path emerging from the laser and before the mirror. In some instances, the data captured during the first data acquisition procedure may have sufficient signal-to-noise ratio to also serve for the requirements of the second data acquisition procedure. In such an instance, the system may be configured to use / acquire the data of the first data acquisition procedure as the required high signal-to-noise ratio data in place of the second data acquisition procedure (step 726) and save this data for later analysis or real time processing. The above discussion is exemplary of the following methods. Figure 8 shows a flow diagram of a method 800 of analysing a biological sample according to an example. The method 800 comprises: - providing 841 a biological sample incubated with a compound of formula I under conditions that allow formation of a Raman-tagged bioconjugate, - focusing 842 an electromagnetic radiation beam onto the biological sample to define a particle capture zone for capturing a candidate particle within the beam, - performing 843 a first data acquisition procedure to test for particle capture, - repeating 844 step 843 if particle capture is not detected, - if a particle capture is detected, acquiring 845 particle data from the captured particle to determine the presence of absence of the Raman-tagged bioconjugate, - reducing 846 the optical beam intensity to a sub-capture level to release the particle from the particle capture zone, and - repeating 847 steps 842-846 for successive particles in the particle-conveying medium. The biological sample may be incubated with any compound of formula I as described herein. Step 845 and, optionally, step 843, comprises a Raman data gathering procedure, preferably a Raman spectroscopy data gathering procedure. One or more steps of the method 800 may involve the use of an automated particle capture system generally as described with reference to Figure 6 (i.e., generally in accordance with the SPARTA®system described and referenced herein). The repetition 847 of steps 842-846 may include one or more steps of the example process described with reference to Figure 7. An automated particle capture system as described above (e.g., SPARTA®) may perform any of the data acquisition and analysis procedures described herein upon executing corresponding computer program code or instructions. The computer program code or instructions may be distributable by electronic data transmission or by computer readable medium / product. Further example methods Figure 9 shows a flow diagram of an in vitro or ex vivo method 900 of detecting the presence or absence of a biomarker and / or biomolecule in a sample, according to an example. The method 900 comprises: - providing 951 a sample, - incubating 952 said sample with a compound of formula I under conditions that allow formation of a Raman-tagged bioconjugate, wherein the Raman-tagged bioconjugate is formed if the biomarker and / or biomolecule is present in the sample, - removing 953 any non-conjugated compound of formula I, - analysing 954 the sample using Raman spectroscopy to detect the presence or absence of the Raman-tagged bioconjugate. Figure 10 shows a flow diagram of a method 1000 of diagnosing a disease or disorder in a subject, according to an example. The method 1000 comprises: - providing 1061 a biological sample previously obtained from a subject, - incubating 1062 said biological sample with a compound of formula I under conditions that allow formation of a Raman-tagged bioconjugate, wherein the Raman-tagged bioconjugate is formed if the biomarker and / or biomolecule is present in the biological sample, - removing 1063 any non-conjugated compound of formula I, - analysing 1064 the biological sample using Raman spectroscopy to detect the presence or absence of the Raman-tagged bioconjugate, wherein detection of the presence of the Raman-tagged bioconjugate indicates that the subject has the disease or disorder. Figure 11 shows a flow diagram of an in vitro or ex vivo method 1100 of imaging a biological sample, according to an example. The method 1100 comprises: - providing 1171 a biological sample, - incubating 1172 said biological sample with a compound of formula I under conditions that allow formation of a Raman-tagged bioconjugate, wherein the Raman-tagged bioconjugate is formed if the biomarker and / or biomolecule is present in the biological sample, - removing 1173 any un-conjugated compound of formula I, - imaging 1174 the biological sample using Raman spectroscopy. With reference to the methods of Figures 8-11, the compound of formula I may be any compound of formula I as described herein. Steps 954 and 1064 may involve performance of the method described with reference to Figure 8 (such a method optionally involving one or more steps of the example process described with reference to Figure 7). Advantageously, this may realise a high throughput Raman measurement capability of biological samples that to date have been challenging to characterise. This realisation is by virtue of tagging the biological samples with water-soluble Raman tag compounds as disclosed herein, which exhibit relatively strong Raman signals in the otherwise silent Raman region (1800-2800 cm-1), then performing an automated Raman analysis, preferably with the SPARTA®platform. Example Reaction Schemes and Methods The reaction schemes described below are intended to provide a general description of the methodology employed in the preparation of the compounds of the invention. The examples provided herein are offered to illustrate but not limit the compounds of the invention, as well as the preparation of such compounds and intermediates. Abbreviations CDCl3: Deuterochloroform d: Doublet d of d: Doublet of doublets d of t: Doublet of triplets DI: Deionised ESI: Electrospray ionisation eq.: Equivalents EtOAc: Ethyl acetate HPLC: High-performance liquid chromatography J: Coupling constant m: Multiplet min: Minute(s) MS: Mass spectrometry m / z: Mass / charge ratio NMR: Nuclear magnetic resonance NEt3: Triethyl amine sat: Saturated s: Singlet t: Triplet TBAF: Tetra-n-butylammonium fluoride t of d: Triplet of doublets TFA: Trifluoroacetic acid THF: Tetrahydrofuran TIPS: Triisopropylsilyl Analytical Methods GC-MS parameters: Column properties: 0.22 mm ID x 0.25 μm film thickness x 12 m length, 5% phenyl-95% methylpolysiloxane; Carrier gas: Helium at 1 ml / min constant flow; Temperature program: starting at 50 °C, hold for 2 min, then with 20 °C / min to 240 °C, 35 °C / min to 300 °C, hold for 3 min; Injector temperature: 230 °C; Injector method: split (1:50) injection of 1 μL; Detector: Quadrupole Mass Spectrometer (MS), mass range used m / z 25-450; Date of analysis: 10 / 05 / 2022; GC-MS analysis number: AC-95198-1- 301A-1. Ref C6D67.16 ppm 128.0 ppm Ref CDCl37.26 ppm and 77.0 ppm Trajan (SGE) Capillary GC Column BPX5, 12m x 0.22mm ID, 0.25μm film thickness, ea. General Procedures Protocol 1: protection of sulfonic acids to form acid labile sulfonate esters Sulfonyl chloride derivative (1.0 eq., scales 1.96 mmol) was dissolved in anhydrous CH2Cl2 to a concentration of 0.49 mmol / mL and 2,2,2-trifluoro-1-(p-tolyl)ethan-1-ol (1.1 eq.) was added to this. The reaction was placed on ice and 1,4-diazabicyclo(2.2.2)octane (1.3 eq.) was dissolved in anhydrous CH2Cl2to a concentration of 2 mmol / mL. The diazabicyclo(2.2.2)octane solution was added dropwise over 10 minutes before allowing to warm to room temperature and stir overnight. The reaction was diluted in CH2Cl2 (50 mL) and washed twice with water (30 mL) and with brine (30 mL). The resultant organic layer was dried (MgSO4) and dried in vacuo. The reaction was dissolved in CH2Cl2(0.1% NEt3) and dry loaded onto silica. Purification by flash column chromatography (hexane (0.1% NEt3) to 50% CH2Cl2) yielded the title compounds. Protocol 2: Sonogashira reactions: To a vial was added the protected halogenated benzene derivative (1.0 eq., scales up to 1.57 mmol), bis(triphenylphosphine)palladium(II) dichloride (0.02 eq), copper(I) iodide (0.02 eq), triphenylphosphine (0.04 eq.) and a magnetic stirrer bar. The vial was sealed with a septum, then anhydrous degassed toluene (5 mL) and degassed N,N- diisopropylamine (0.63 mL) were added. The reaction mixture was bubbled with argon for 10 minutes then argon purged (triisopropylsilyl)acetylene (0.422 mL, 1.88 mmol, 1.2 eq) was added. The reaction was heated at 70 °C for 12 hours. Reaction cooled to room temperature, diluted in hexane and filtered through celite. The filtrate was then dried in vacuo and the crude reaction mixture purified using flash column chromatography (hexane (0.1% Net3) to 10% ethyl acetate in hexane (0.1% Net3). The reaction mixture was then dissolved in toluene (30 mL) and 150 mL of diethyl ether was added, this was filtered and the filtrate collected and dried in vacuo to yield the title compounds. Protocol 3: TIPS deprotection with TBAF: To a vial was added TIPS protected alkyne (1.0 eq., scales up to 0.59 mmol) and a stirrer bar. This purged with nitrogen and dry THF (0.3 mL / mmol) was added. The solvent was degassed for 10 minutes and 1 M TBAF in THF (1.4 eq.) was added. This was stirred for 2 hours. The reaction was dried in vacuo and CH2Cl2(50 mL) was added, this was washed with brine (50 mL) and the organic layer extracted. Purification by flash column chromatography (1:1 Hexane (0.1% NEt3):CH2Cl2) to yield the title compound. Protocol 4: one pot TIPS deprotection and bromination: TIPS protected alkyne (1.0 eq., scales up to 7.89 mmol) was added to a round bottom flask and dissolved in HPLC grade acetonitrile (10 mL / mmol). The reaction was covered in aluminium foil and placed on a hotplate stirrer. To the reaction mixture was added N- bromosuccinimide (1.21 eq.), followed by silver(I) fluoride (1.22 eq.) at room temperature. After 2 hours of stirring, the reaction was filtered through celite, rinsed with acetonitrile (2x25 mL), and then rinsed with dichloromethane (3x30 mL) into a separating funnel. The organic layer was then washed with water (3x100 mL) and brine (1x100 mL), dried with anhydrous sodium sulfate, filtered, and concentrated via rotary evaporation. The crude solid was dry-loaded onto silica using dichloromethane and purified via flash chromatography using 5% ethyl acetate in hexane to give the title compound. Protocol 5: Cadiot-Chodkiewicz coupling: To a 7 mL vial with a rubber septum was added a magnetic stirrer bar. The flask was evacuated and refilled with nitrogen five times. Then nitrogen purged diethyl ether (1 mL / 0.2 mmol) was added. A solution containing CuCl (0.05 eq.) dissolved in n-butylamine (6 mL / 0.2 mmol) was then added to the reaction vial. A solution of hydroxylamine hydrochloride (excess but consistently < 0.1 g) dissolved in diethyl ether was added to the reaction mixture to give a colourless solution. Then the alkyne (1.2 eq, 0.24 mmol to 0.024 mmol) dissolved in purged diethyl ether (5 mL / 0.2 mmol) was added to the reaction to give a yellow precipitate. The bromo alkyne (1.0 eq., 0.20 to 0.02 mmol) dissolved in nitrogen purged diethyl ether (5 mL / 0.2 mmol) was added dropwise and the reaction mixture was allowed to stir overnight at room temperature. The reaction mixture was diluted with diethyl ether (50 mL), washed with sat. NH4Cl solution, water (3x) and brine, then dried with Na2SO4, filtered and dry loaded onto silica via rotary evaporation. The crude reaction mixture was purified using flash column chromatography using a gradient from 0% EtOAc in hexane to 20% EtOAc in hexane. Protocol 7: deprotection conditions for acid labile protecting groups: To a vial containing a stirrer bar the oligoalkyne moiety (scales up to 0.05 mmol) was added and dissolved in anhydrous DCM (10 mL / mmol). TFA (10 mL / mmol) was added and the reaction allowed to stir for 2 hours at room temperature. The reaction was precipitated, filtered and the precipitate washed with diethyl ether (2 x 10 mL) before drying under vacuum to yield the title compound. Compound Examples Intermediate S1-O-C: 2,2,2-trifluoro-1-(p-tolyl)ethyl 2-bromobenzenesulfonate Reaction carried out according to Protocol 1 with 2-bromobenzenesulfonyl chloride as the starting material. Column chromatography (hexane with 0.1% triethyl amine to 20% ethyl acetate gradient) yielded Intermediate S1-O-C as a colourless oil that solidified upon standing to a white solid (86%).1H NMR (400 MHz, CDCl3): d 7.92 (1H, m, Hd), 7.66 (1H, m, Ha), 7.36 (2H, m, Hb & Hc), 7.26 (2H, d, Hf), 7.09 (2H, d, J = 9.78 Hz, Hg), 5.69 (1H, q, J = 6.59 Hz, He), 2.32 (3H, s, Hh).13C NMR (150 MHz, CDCl3): d 140.85, 136.54, 135.70, 134.77, 131.75, 129.41, 128.41, 127.50, 126.18, quartet (125.15, 123.28, 121.43, 119.56, J = 281.86 Hz), 121.22, quartet (75.90, 79.56, 79.21, 78.87, J = 34.01 Hz), 21.39. 75.61. HPLC: Elution time 6.6 min. Intermediate S2-O-C: -2,2,2-trifluoro-1-(p- Reaction carried out according to Protocol 2 with Intermediate S1-O-C as the starting material. Column chromatography (hexane with 0.1% triethyl amine to 5% ethyl acetate gradient) yielded Intermediate S2-O-C as a pale yellow oil (81%). 129.24, quartet (128.27, 126.42, 123.29, 119.27, J = 279.37 Hz) 127.91, 102.00, 101.71, quartet (79.71, 79.37, 79.03, 78.69, J = 34.30 Hz), 21.35, 18.71, 11.52.19F NMR (400 MHz, CDCl3): d -75.78, HPLC: Elution time 7.6 min. MS (ESI-MS, m / z): Calculated for [C26H33F3O3SSi +Na]+= 533.18, mass found: 533.2. Intermediate S3-O-C: 2,2,2-trifluoro-1-(p-tolyl)ethyl 2-ethynylbenzenesulfonate Reaction carried out according to Protocol 2 with Intermediate S2-O-C as the starting material. Column chromatography (hexane with 0.1% triethyl amine to 10% ethyl acetate gradient) yielded Intermediate S3-O-C as a pale yellow oil (100%). 7.84 (1H, d, J = 8.18 Hz, Hd), 7.57 (1H, d, J = 7.87 Hz, Ha), 7.48 (1H, t, J = 7.46 Hz, Hb), 7.35 (1H, t, J = 7.46 Hz, Hc), 7.24 (2H, d, J = 7.94 Hz, Hf), 7.07 (2H, d, J = 7.94 Hz, Hg), 5.74 (1H, quartet, J = 6.26 Hz, He), 3.35 (1H, s, Hi), 2.29 (3H, s, Hh).13C NMR (150 MHz, CDCl3): d 140.64, 137.98, 135.53, 133.45, 129.69, 129.33, 128.72, 128.31, 126.42, quartet (125.25, 123.33121.42, 119.59, J = 280.16 Hz), 121.77, 86.29, Quartet (79.33, 79.09, 78.86, 78.68, J = 34.0 Hz), 79.16, 21.32. MS (ESI-MS, m / z): Calculated for [C17H13F3O3S +Na]+= 377.03, mass found: 377.0. Intermediate S1-M-C: 2,2,2-trifluoro-1-(p-tolyl)ethyl 3-bromobenzenesulfonate Reaction carried out according to Protocol 1 with 3-bromobenzenesulfonyl chloride as the starting material. Product isolated by column chromatography (hexane with 0.1% triethyl amine to 20% ethyl acetate gradient) yielded Intermediate S1-M-C as an oil that solidified upon standing (76%). 7.72 (1H, t, J = 1.75 Hz, Hd), 7.70 (1H, m, Ha), 7.66 (1H, m, Hc), 7.29 (1H, t, J = 8.25 Hz, Hb), 7.19 (2H, d, J = 8.11 Hz, Hf), 7.11 (2H, d, J = 8.04 Hz, Hg), 5.67 (1H, quartet, J = 6.10 Hz, He), 2.34 (3H, s, Hh).13C NMR (150 MHz, CDCl3): d 141.10, 138.21, 137.05, 130.91, 130.60, 129.59, 128.37, 126.48, 126.11, 123.01, quartet (125.09, 123.22, 121.36, 119.50, J = 280.88 Hz), quartet (79.49, 79.26, 79.03, 78.90 , J = 33.28 Hz), 21.45.19F NMR (400 MHz, CDCl3): d -75.86, HPLC: Elution time 6.6 min. Intermediate S2-M-C: 2,2,2-trifluoro-1-(p-tolyl)ethyl 3-( Reaction carried out according to Protocol 2 with Intermediate S1-M-C as the starting material. Column chromatography (hexane with 0.1% triethyl amine to 5% ethyl acetate gradient) yielded Intermediate S2-M-C as an oil that solidified upon standing (75%).1H NMR (400 MHz, CDCl3): d 7.73 (1H, t, J = 1.64 Hz, Hd), 7.65 (1H, m, Ha), 7.59 (1H, m, Hb), 7.33 (1H, t, J = 7.95 Hz, Hb), 7.17 (2H, d, J = 8.35 Hz, Hf), 7.07 (2H, d, J = 7.91 Hz, Hg), 5.65 (1H, q, J = 6.10 Hz, He), 2.31 (3H, s, Hh), 1.13 (m, 21H, Hi & Hj). NMR (101 MHz, CDCl3): d 140.69, 137.04, 136.57, 131.09, 129.35, 128.95, 128.12, 127.06, 126.17, quartet (124.98, 123.12, 121.26, 119.40, J = 280.34 Hz), 124.94, 94.14, quartet (79.03, 78.81, 78.58, 78.35, J = 36.49 Hz), 21.25, 18.63, 11.23.19F NMR (400 MHz, CDCl3): d -75.93, HPLC: Elution time 7.7 min. MS (ESI-MS, m / z): Calculated for [C26H33F3O3SSi+Na]+= 533.19, mass found: 533.2. Intermediate S3-M-C: 2,2,2-trifluoro-1-(p-tolyl)ethyl 3-ethynylbenzenesulfonate Reaction carried out according to Protocol 3 with Intermediate S2-M-C as the starting material. Column chromatography (hexane with 0.1% triethyl amine to 10% ethyl acetate gradient) yielded Intermediate S3-M-C colourless oil (78%).1H NMR (400 MHz, CDCl3): d 7.75 (1H, t, J = 1.53 Hz, Hd), 7.71 (1H, m, Ha), 7.63 (1H, m, Hc), 7.37 (1H, t, J = 7.95 Hz, Hb), 7.19 (2H, d, J = 8.28 Hz, Hf), 7.09 (2H, d, J = 8.28 Hz, Hg), 5.67 (1H, quartet, J = 6.60 Hz, He), 3.17 (1H, s, Hi), 2.33 (S, 3H, Hh).13C NMR (101 MHz, CDCl3): d 140.97, 137.24, 136.95, 131.48, 129.57, 129.23, 128.34, 127.84, 126.28, quartet (125.67, 124.69, 123.26, 121.4, J = 280.10 Hz), 123.76, 81.23, 79.90, quartet (79.30, 79.07, 78.84, 78.61, J = 32.34 Hz), 21.42. 75.89, MS (ESI-MS, m / z): Calculated for [C17H13F3O3S+H]+= 355.05, mass found: 355.1.

[0002] P- 1- 4-iodobenzenesulfonate Reaction carried out following protocol 1 with 4-iodobenzenesulfonyl chloride as the starting material. Product isolated by column chromatography (hexane with 0.1% triethyl amine to 20% ethyl acetate gradient) yielded Intermediate S1-P-C as a white crystalline solid (78%). 7.75 (2H, d, J = 8.33 Hz, Hb), 7.41 (2H, d, J = 8.73 Hz, Ha), 7.16 (2H, d, J = 8.25 Hz, Hd), 7.09 (2H, d, J = 7.94 Hz, He), 5.63 (1H, h, J = 6.33 Hz, Hc), 2.33 (3H, s, Hf).13C NMR (101 MHz, CDCl3): d 140.99, 138.47, 136.10, 129.57, 129.18, 128.29, 126.32, quartet (125.49, 123.70, 120.90, 119.11, J = 278.89 Hz), 102.04, quartet (79.35, 79.01, 78.66, 78.32, J = 34.78 Hz), 21.46.19F NMR (400 MHz, CDCl3): d -75.91, HPLC: Elution time 6.7 min. MS (ESI-MS, m / z): Calculated for [2 C15H12F3IO3S+Na]+= 934.9, mass found: 934.9. Intermediate S2-P-C: 2,2,2-trifluoro-1-(p-tolyl)ethyl 3-ethynylbenzenesulfonate Reaction carried out following protocol 2 with Intermediate S1-P-C as the starting material. Product isolated by column chromatography (hexane with 0.1% triethyl amine to 20% ethyl acetate gradient) to yield Intermediate S2-P-C as a colourless oil (80%).1H NMR (600 MHz, CDCl3): d 7.65 (2H, d, J = 8.71, Hb), 7.45 (2H, d, J = 8.56, Ha), 7.18 (2H, d, J = 8.01 Hz, Hd), 7.10 (2H, d, J = 7.94 Hz, He), 5.64 (1H, h, J = 6.46 Hz, Hc), 2.33 (3H, s, Hf), 1.14 (21H, m, Hg & Hh).13C NMR (101 MHz, CDCl3): d 140.84, 135.43, 132.47, 129.53, 128.26, 127.87, 126.49, quartet (125.54, 123.75, 120.95, 118.16, J = 284.6 Hz), 104.89, 96.66, quartet (79.22, 78.87, 78.53, 78.19, J = 31.87 Hz), 21.36, 18.75, 11.36.19F NMR (400 MHz, CDCl3): d -75.95, HPLC: Elution time 7.8 min. Intermediate S3-P-C: 2,2,2-trifluoro-1-(p-tolyl)ethyl 4-ethynylbenzenesulfonate Reaction carried out following protocol 3 with Intermediate S2-P-C as the starting material. Product isolated by column chromatography (hexane with 0.1% triethyl amine to 10% ethyl acetate gradient) yielded Intermediate S3-P-C as a white crystalline solid (80%).1H NMR (600 MHz, CDCl3): d 7.69 (2H, d, J = 8.70, Hb), 7.49 (2H, d, J = 8.60, Ha), 7.19 (2H, d, J = 7.35 Hz, Hd), 7.11 (2H, d, J = 7.35 Hz, He), 5.65 (1H, q, J = 6.19 Hz, Hc), 3.28 (1H, s, Hg), 2.34 (3H, s, Hf).13C NMR (101 MHz, CDCl3): d 140.79, 136.08, 132.53, 129.41, 128.22, 128.10, 127.79, 126.28, quartet (124.98, 123.12, 121.26, 119.39, J = 273.97 Hz), 81.56, quartet (78.96, 78.74, 78.51, 78.28, J = 31.99 Hz), 21.24. 75.95. MS (ESI-MS, m / z): Calculated for [C17H13F3O3S+H]+= 355.05, mass found: 355.1. Intermediate S4B: tert-butyl 4-((triisopropylsilyl)ethynyl)benzoate Product synthesised following conditions from Protocol 2 and using tert-butyl-4- bromobenzoate as the starting material. Intermediate S4B was isolated as a clear viscous liquid (69%). = 8.4 Hz, Hb), 7.49 (2H, d, J = 8.5 Hz, Ha), 1.59 (9H, s, Hc), 1.14 (21H, s, He & Hd).13C NMR (101 MHz, CDCl3): į^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 28.33, 18.79, 11.43. MS (ESI-MS, m / z): Calculated for [C22H34O2Si+Na]+= 381.59, found 381.3. Intermediate S5B: tert-butyl 4-(bromoethynyl)benzoate Synthesised according to Protocol 4 with Intermediate S4B as the starting material. Intermediate S5B was yielded as a colourless oil that crystallised into a white solid upon storage in the freezer (91%). 7.87 (2H, d, J = 8.6 Hz, Hb), 7.51 – 7.45 (2H, d, J = 8.6 Hz, Ha), 1.59 (9H, s, Hc).13C NMR (101 MHz, CDCl3): į^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Intermediate S6B: tert-butyl 4-((triisopropylsilyl)buta-1,3-diyn-1-yl)benzoate Product synthesised following conditions from Protocol 2 and using Intermediate S5B as the starting material. Intermediate S6B was yielded as a white solid (70%).1H NMR (400 MHz, CDCl3): į^^^^^^^^+^^G^ J = 8.69, Hb), 7.52 (2H, d, J = 8.69 Hz, Ha), 1.57 (9H, s, Hc), 1.11 (s, 21H, He & Hd). MS (ESI-MS, m / z): Calculated for [2C24H34O2Si+Na]+= 787.46, mass found: 787.5. Intermediate S7B: tert-butyl 4-(bromobuta-1,3-diyn-1-yl)benzoate Synthesised according to Protocol 4 with Intermediate S6B as the starting material. Purification by aqueous work up with CH2Cl2 (50 mL) washed twice DI water (25 mL) isolated Intermediate S7B as a white solid (91%). J = 8.73 Hz. Hb), 7.52 (2H, , J = 8.67 Hz, Ha), 1.58 (9H, s, Hc).13C NMR (101 MHz, CDCl3): į 164.94, 132.71, 131.65, 129.47, 125.25, 81.65, 76.76,73.55, 65.32, 46.17, 28.27. MS (ESI-MS, m / z): Calculated for [C15H13BrO2+H]+= 304.00, mass found: 305+307. Intermediate S8B: tert- Product synthesised following conditions from Protocol 2 and using Intermediate S7B as the starting material. Intermediate S8B was yielded as a white solid (70%). į^^^^^^^^+^^G^ J = 8.26 Hz, Hb), 7.52 (2H, d, J = 8.32 Hz, Ha), 1.57 (9H, s, Hc), 1.08 (21H, s, He & Hd).13C NMR (101 MHz, CDCl3): į^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 81.71, 75.71, 68.55, 60.29, 31.01, 28.25, 18.63, 11.39. MS (ESI-MS, m / z): Calculated for [2C26H34O2Si +Na]+= 835.47, mass found: 835.4. Intermediate BD-o-TolylCF3-Prot: tert-butyl 4-((2-((2,2,2-trifluoro-1-(p- buta-1,3-diyn-1- yl)benzoate Synthesis carried out using Protocol 5 with Intermediate S5B and Intermediate S3-O-C as the starting material. The title compound was isolated as a white solid (98%).1H NMR (600 MHz, DMSO): į 7.99 (2H, d of t, J = 8.78 & 1.81 Hz, Hb), 7.90 (1H, d of d, J = 8.00 & 1.14 Hz, Hg), 7.61 (3H, m, Hd, & Ha), 7.52 (1H, t of d, J = 7.36 & 1.15 Hz, He), 7.40 (1H, t of d, J = 7.65 & 1.47 Hz, Hf), 7.29 (2H, d, J = 7.99 Hz, Hi), 7.10 (2H, d, J = 7.96 Hz, Hj), 5.76 (1H, q, 6.45 Hz, Hh), 2.29 (3H, s, Hk), 1.61 (9H, s, Hc).13C (150 MHz, CDCl3): į 164.92, 140.60, 138.21, 135.76, 133.42, 132.79, 132.49, 129.88, 129.52, 129.33, 129.07, 128.99, 128.88, 128.25, 126.37, 125.38, 121.31, 116.64, 115.72, 81.90, 81.68, 78.77, 75.83, 70.64, 64.49, 28.23, 21.33, 19.16, 13.78.19F NMR (400 MHz, CDCl3): į^-75.78, HPLC: Elution time 7.2 min. UV-Vis wavelength peaks (nm): 304, 326, 348. MS (ESI-MS, m / z): Calculated for [C30H25F3O5S+H]+= 555.14, mass found: 555.2. Intermediate BD-m-TolylCF3-Prot: 137.40, 137.20, 133.60, 132.86, 132.53, 131.78, 129.60, 129.41, 128.39, 128.19, 126.18, 125.37, 124.73, 123.29, 120.91, 81.79, 79.85, 79.25, 19.94, 76.14, 75.63, 29.85, 28.31, 21.44, 14.28.19F NMR (400 MHz, CDCl3): į^-75.87, HPLC: Elution time 7.3 min. UV-Vis wavelength peaks (nm): 300, 316, 338. Intermediate BD-p-TolylCF3-Prot: Synthesis carried out using Protocol 5 with Intermediate S5B and Intermediate S3-P-C as the starting material. Intermediate 17 was isolated as a white solid (38%).1H NMR (600 MHz, CDCl3): į 7.97 (2H, d of t, J = 8.71 & 1.86 Hz, Hb), 7.70 (2H, d of t, J = 8.64 & 1.83 Hz, He), 7.58 (2H, d of t, J = 8.60 & 1.83 Hz, Ha), 7.52 (2H, d of t, J = 8.77 & 1.88 Hz, Hd), 7.19 (2H, d, J = 8.07 Hz, Hg), 7.12 (2H, d, J = 7.86 Hz, Hh), 5.67 (1H, q, J = 6.33 Hz, Hf), 2.35 (3H, s, Hi), 1.60 (9H, s, Hc).13C NMR (150 MHz, CDCl3): į 174.67, 144.16, 140.92, 138.89, 136.41, 132.88, 132.47, 129.54, 129.51, 128.20, 127.96, 127.81, 125.17, 81.74, 80.17, 78.93, 78.59, 75.50, 28.23, 21.37, 19.62, 15.52.19F NMR (400 MHz, CDCl3): į^-75.92, HPLC: Elution time 7.3 min. UV-Vis wavelength peaks (nm): 302, 322, 344. Intermediate triyne-m-TolylCF3-Prot: tert-butyl 4-((3-((2,2,2-trifluoro-1-(p-tolyl)ethoxy)sulfonyl)phenyl)hexa-1,3,5-triyn-1- yl)benzoate Synthesis carried out using Protocol 5 with Intermediate S7B and Intermediate S3-M-C as the starting material. The product was isolated as a white solid (34%).1H NMR (600 MHz, CDCl3): į 7.96 (2H, d of t, J = 8.57 & 1.37 Hz, Hb), 7.77-7.73 (1H, m, He), 7.71 (1H, t, J = 1.59 Hz, Hg), 7.65 (1H, d of t, J = 7.85 & 1.43 Hz, Hf), 7.59 (2H, d of t, J = 8.57 & 1.88 Hz, Ha), 7.39 (2H, t of d, J = 7.85 & 0.37 Hz, Hd), 7.18 (2H, d, J = 8.12 Hz, Hi), 7.10 (2H, d, J = 7.93 Hz, Hj), 5.67 (1H, q, J = 6.44 Hz, Hh), 2.35 (3H, s, Hk).13C NMR (150 MHz, CDCl3): į^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 128.46, 128.38, quartet (128.25, 126.02, 124.69, 122.14), 122.53, 81.71, quartet (79.16, 78.92, 78,63, 78.25), 76.37, 76.13, 67.57, 66.71, 58.72, 28.18, 15.25, 14.15. & Hg), 7.71 (1H, d, J = 7.6 Hz, Hf), 7.54 (1H, d, J = 7.6 Hz, Hd), 7.43 (1H, t, J = 7.74 Hz, He).13C NMR (150 MHz, d6-DMSO): į^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 129.73, 129.12, 127.79, 125.15, 120.05, 83.23, 81.39, 76.26, 73.59. HPLC: Elution time 6.0 min. UV-Vis wavelength peaks (nm): 300, 320, 342. HR-MS (ESI-MS, m / z): Calculated for [C17H10O5S-H]-= 325.02, mass found: 325.0187. Synthesis carried out using Protocol 7 with Intermediate BD-p-TolylCF3-Prot as the starting material. The product was isolated as a white solid (100%).1H NMR (600 MHz, d6-DMSO): į 7.97 (2H, d, J = 8.4 Hz, Hb), 7.73 (2H, d, J = 8.3 Hz, Ha), 7.64 (2H, d, J = 8.2 Hz, He), 7.59 (2H, d, J = 8.2 Hz, Hd).13C NMR (150 MHz, d6-DMSO): į^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 125.16, 120.47, 83.38, 81.55, 76.26, 74.06. HPLC: Elution time 6.0 min. UV-Vis wavelength peaks (nm): 300, 320, 342. HR-MS (ESI-MS, m / z): Calculated for [C17H10O5S-H]-= 325.02, mass found: 325.0186. Synthesised using Protocol 7 using Intermediate triyne-m-tolylCF3as the starting material to yield the title compound as a white solid (100%). 7.97 (2H, d, J = 7.62 Hz, Hb), 7.79-7.76 (3H, m, Ha & Hf), 7.72 (1H, d, J = 7.62 Hz, He), 7.61 (1H, d, J = 7.60 Hz, Hc), 7.43 (1H, t, J = 7.59 Hz, Hd).13C NMR (150 MHz, d6-DMSO): į^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 128.92, 124.15, 119.13, 112.97, 111.07, 78.78, 76.22, 69.99, 59.65, 50.80, 42.01. HPLC: Elution time 6.5 min. UV-Vis wavelength peaks (nm): 316, 340, 366. HR-MS (ESI-MS, m / z): Calculated for [C19H10O5S-H]-= 349.02, mass found: 349.0189. Example 5: 4-((2-sulfophenyl)octa-1,3,5,7-tetrayn-1-yl)benzoic acid The title compound is prepared from methyl 4-((2-((2,2,2- trifluoroethoxy)sulfonyl)phenyl)octa-1,3,5,7-tetrayn-1-yl)benzoate (below) in according with procedure known to the person skilled in the art. Formation of methyl 4-((2-((2,2,2-trifluoroethoxy)sulfonyl)phenyl)octa-1,3,5,7-tetrayn- 1-yl)benzoate (Example 5 precursor) Synthesised using Protocol 2 using methyl 4-(bromohexa-1,3,5-triyn-1-yl)benzoate and 2,2,2-trifluoroethyl 2-ethynylbenzenesulfonate as starting materials to yield the title compound as a yellow solid (17%). 8.06 (1H, dd, J = 8, 1.4 Hz), 8.02 (2H, d, J = 8.4 Hz), 7.79 (1H, dd, J = 7.6, 1.4 Hz), 7.67 (1H, td, J = 7.7, 1.4 Hz), 7.63 – 7.56 (3H, m), 4.53 (2H, q, J = 7.9 Hz), 3.93 (3H, s). UV-Vis wavelength peaks (nm): 322, 348, 374, 404. MS (ESI-MS, m / z): Calculated for [C24H13F3O5SNa]+= 493.03, mass found: 493.0. Raman Spectroscopy of Compound Examples The compounds were measured as dry powders which were initially dissolved in methanol, and aliquoted onto calcium fluoride slides, and allowed to dry at room temperature. Data was acquired using a 532 nm excitation laser and single point spectra. All data was processed in the WITec product FIVE software, and pre-processed by 1) shape fitting the background subtraction and 2) normalising to the symmetrical &ʵ& peak intensity. The data shows the Raman spectra between 2050 – 2300 cm-1obtained from compound Examples 1 and 4 and Example 5 precursor (2-yne, 3-yne and 4-yne, respectively). The results are shown graphically in Figure 1. Antibody Conjugation Example 1 Extracellular vesicles (EVs) were isolated from HEK293F CD63 overexpressing cell lines using the methods as previously described in Penders et al. ACS Nano 15, 18192–18205. The EV isolates were measured using Nanoparticle Tracking Analysis (NTA, Nanosight NS300) and matched at a concentration of 1x1011particles / mL, diluting using PBS where necessary. The EVs were incubated for 2 hours at room temperature with the Raman-tagged antibody added as 100 or 1000 equivalents (Ab:EV). The Raman-tagged antibody was produced in accordance with the preparation described in Antibody Conjugation Example 2 (below). SPARTA®measurements were performed (as previously described in Penders et al. ACS Nano 15, 18192–18205). A measurement run without the Rab was conducted as a control. The obtained SPARTA®raw spectra were processed (see spectral processing as previously described in Penders et al. ACS Nano 15, 18192–18205). The results are shown graphically in Figure 2. Antibody Conjugation Example 2 The Raman tag (Example 2) was taken and dissolved in DMSO to produce a stock solution. This was vortexed and a dilution series of tag was made up in anhydrous DMSO. To 50 μL of CD63 antibody in BBS (1.0 eq.) was added 2.5 μL of the resultant concentration series and the solutions were incubated at room temperature for 3 hours. The resultant solutions were diluted in DPBS (0.5 mL, pH 7.4) and filtered using 10 KDa MWCO 0.5 mL Viva spin filters by centrifuging at 16500 rcf for 6.5 minutes. This was repeated 6 times before the resultant supernatant was made up to 30 μL. 5 μL of this solution was taken, diluted with 95 μL of DPBS and UV-Vis carried out. The results are shown graphically in Figure 3. Antibody Conjugation Example 3 An Agilent 2100 Bioanalyzer was used to measure the molecular weight of the conjugated antibody. Samples were run according to manufacturer instructions following the Protein 230 Assay Protocol. A 6 μL aliquot of ladder was mixed thoroughly with a 4 μL aliquot of 10 μM Raman tagged antibody, then loaded onto the well. The results are shown graphically in Figure 4, demonstrating no aggregation of the Raman tagged antibody. Antibody Conjugation Example 4 Modification of an anti-CD63 antibody with a Raman tag derivative without solubilsing groups was attempted. To prepare an activated Raman tag solution, a 40 mM stock solution of Raman tag was prepared in DMSO (25 μL). To this solution was added a solution of EDC in 1xPBS (1.5 eq, 12.5 μL, 120 mM), which was then allowed to incubate at 37 ºC for 10 minutes. Then, a solution of sulfo-NHS in 1xPBS (2 eq, 12.5 μL, 160 mM)) was added, followed by an additional 50 μL of DMSO, then the reaction was incubated at 37 ºC for 30 minutes. The activated Raman tag solution (30 eq, 3 μL, 10 mM) was mixed with anti-CD63 antibody (50 μL, 20 μM in BBS pH = 8.0) and incubated at room temperature for 4 hours. The reaction mixture was then transferred to a 10 kDa MWCO 0.5 mL VivaSpin filter and washed with 1x PBS solution (6 x 0.5 mL). The resulting solution was analysed via UV-Vis, with the concentration of the antibody (14.6 μM) determined by the absorbance at 280 nm. The absorbance of the Raman tag at 326 nm and an extinction coefficient of 26499 M-1cm-1was used to determine the concentration of the Raman tag conjugated to the anti-CD63 antibody. A correction factor of 0.502 was applied to account of absorbance at 280 nm by the Raman tag (13309 M-1cm-1 / 26499 M-1cm-1). The Raman tagged antibody stock was diluted 1:10 (v / v) in 1xPBS, with the concentration of the antibody measured at 3.74 μM, and the concentration of the Raman tag at 1.17 μM. This gives an average degree of modification of 0.31 Raman tags per anti-CD63 antibody. Tag Concentration Calculations Example workings for calculation of tag bio-conjugation efficiency and tags per antibody using UV-Vis spectroscopy. The extinction co-efficient of a Raman tag molecule (i.e. a compound of the invention) is calculated using a dilution series from a known concentration of the Raman tag. The extinction co-efficient of a functionalised (i.e. Raman tagged) antibody moiety is calculated similarly. A peak correction factor is used to account for the contribution of the Raman tag at 280 nm (the absorbance of the antibody) to allow accurate characterisation of the ratio of Raman tag to protein. An example utilising Example 2 tagged to anti-human serum albumin (anti-HSA) is described. The Raman-tagged antibody was produced in accordance with the preparation described in Antibody Conjugation Example 2 (above). The extinction co-efficient of the Raman tag is calculated to be 16,747 cm-1M-1using a peak at 345 nm. IgG antibody extinction co-efficient is calculated to be 210,000 cm-1M-1. The ratio of peaks at 345 nm to 280 nm is 0.834, which is used as a correction factor in these calculations to account for the contribution of the Raman tag at 280 nm. Example calculations using data from UV-Vis spectroscopy of a solution of Raman tagged antibody is displayed below: ^ = ^^^ ^ ^^= ^ Worked example for functionalisation of anti-HSA: (0.1416747 ^^ି^8^ି^ × 1 ^^)^൬0.405 െ (0.148 × 0.834)210,000 Other embodiments are intentionally within the scope of the accompanying claims.

Claims

CLAIMS 1. A compound of formula I,wherein: A and B are each independently an aromatic group; each R1is independently selected from the group consisting of -S(O)2OH, -S(O)OH, -OS(O)2OH, -S(O)2NH2, -P(O)(OH)2, -OP(O)(OH)2, -P+(R3)3, -N+(R3)3, -OH, -C(O)OH, -NHC(O)OH, a 5- or 6-membered heterocyclylalkyl group, a 5- or 6-membered heteroaryl group, a zwitterionic group, and a PEG group; L1is a bond or a suitable linking group; R2is a group capable of being conjugated to a biomarker and / or biomolecule; each R3is independently selected from the group consisting of hydrogen and a C1-4 alkyl group; m is 1, 2 or 3; and n is 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, or a salt or solvate thereof.

2. The compound according to Claim 1, wherein the compound of formula I is a compound of formula IA,wherein R1, R2, m and n are as defined in Claim 1.

3. The compound according to Claim 1 or Claim 2, wherein R1is selected from the group consisting of -S(O)2OH, -P(O)(OH)2, and -N+(R3)3.

4. The compound according to any one of Claims 1 to 3, wherein R1is -S(O)2OH.

5. The compound according to any one of Claims 1 to 4, wherein L1is a bond.

6. The compound according to any one of Claims 1 to 5, wherein R2is a group, wherein L2is a bond or a suitable linking group; R4is selected from the group consisting of -C(O)OR5, -C(O)Cl, -NCO, -NCS,group, which C1-4alkyl group is optionally substituted with one or more phenyl groups; and R6is selected from the group consisting of hydrogen and a C1-4 alkyl group.

7. The compound according to Claim 6, wherein: R4is -C(O) L2is a bondgroup.

8. The compound according to any one of Claims 1 to 7, wherein R2is -C(O)OH.

9. The compound according to any one of Claims 1 to 8, wherein n is 2, or 3.

10. The compound according to any one of Claims 1 to 9, wherein m is 1.

11. The compound according to any one of Claims 1 to 10, wherein the biomarker and / or biomolecule is selected from the group consisting of an antigen, an antibody, a peptide, a protein, a nucleic acid, a vesicle, or a carbohydrate.

12. The compound according to any one of Claims 1 to 11, wherein the compound is selected from the group consisting of:or a salt or solvate thereof.

13. A Raman-tagged bioconjugate formed from a compound of formula I as defined in any one of Claims 1 to 12 and a biomarker and / or biomolecule.

14. The Raman-tagged bioconjugate as defined in Claim 13, wherein the biomarker and / or biomolecule is selected from the group consisting of an antigen, an antibody, a peptide, a protein, a nucleic acid, a lipid, a vesicle and a carbohydrate.

15. Use of a compound of formula I as defined in any one of Claims 1 to 12 in the preparation of a Raman-tagged bioconjugate as defined in Claim 13 or Claim 14.

16. A Raman-tagged bioconjugate as defined in Claim 13 or Claim 14 for use in medicine.

17. A method of detecting the presence or absence of a biomarker and / or biomolecule in a sample, wherein the method comprises the steps of: a) providing a sample; b) incubating said sample with a compound of formula I as defined in any one of Claims 1 to 12 under conditions that allow formation of a Raman-tagged bioconjugate as defined in Claim 13 or Claim 14, wherein the Raman-tagged bioconjugate is formed if the biomarker and / or biomolecule is present in the sample;c) removing any non-conjugated compound of formula I; and, d) analysing the sample using Raman spectroscopy to detect the presence or absence of the Raman-tagged bioconjugate.

18. A method of diagnosing a disease or disorder in a subject, wherein the method comprises the steps of: a) providing a biological sample previously obtained from a subject; b) incubating said biological sample with a compound of formula I as defined in any one of Claims 1 to 12 under conditions that allow formation of a Raman-tagged bioconjugate as defined in Claim 13 or Claim 14, wherein the Raman-tagged bioconjugate is formed if the biomarker and / or biomolecule is present in the biological sample; c) removing any non-conjugated compound of formula I; and, d) analysing the biological sample using Raman spectroscopy to detect the presence or absence of the Raman-tagged bioconjugate, wherein detection of the presence of the Raman-tagged bioconjugate indicates that the subject has the disease or disorder.

19. An in vitro or ex vivo method of imaging a biological sample, wherein the method comprises the steps of: a) providing a biological sample; b) incubating a compound of formula I as defined in any one of Claims 1 to 12 with the biological sample so as to form a Raman-tagged bioconjugate as defined in Claim 13 or Claim 14, wherein the Raman-tagged bioconjugate is formed if the biomarker and / or biomolecule is present in the biological sample; c) removing any non-conjugated compound of formula I; and d) imaging the biological sample using Raman spectroscopy.

20. A kit of parts comprising:a) a compound of formula I as defined in any one of Claims 1 to 12; and b) instructions for using the compound of formula I as defined in any one of Claims 1 to 12 in an in vitro or ex vivo method of detecting the presence or absence of a biomarker and / or biomolecule in a sample, a method of diagnosing a disease or disorder in a subject and / or a method of imaging a biological sample.

21. A process for preparing a compound of formula I as defined in any one of Claims 1 to 12, comprising reacting a protected derivative of a compound of formula I in the presence of a suitable deprotecting agent.

Images