PH and light dual-response supramolecular particle as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of intelligent response type drug delivery systems, and particularly relates to a pH and light dual-response supramolecular particle as well as a preparation method and application thereof. The invention relates to a pH and light dual-response supramolecular particle, which comprises: a polymer matrix, which is an alginic acid grafted beta-cyclodextrin derivative (OSA-beta-CD); the guest molecule is a hydrophobic molecule containing an adamantyl group; and polyvalent metal crosslinking ions. The Fe < 3 + >-OSA-beta-CD / Ad-EF supramolecular particle with a clear structure is constructed by comprehensively utilizing the synergistic effect of supramolecular acting forces such as hydrophobic interaction, hydrogen-bond interaction and metal coordination and adopting a macroscopic hydrophobic module and an ionic cross-linked network, and a drug controllable release function of the supramolecular particle under an acidic microenvironment and an illumination triggering condition is realized.

Description

Technical Field

[0001] This invention belongs to the technical field of intelligent responsive drug delivery systems, specifically relating to a pH and light-responsive supramolecular microparticle, its preparation method, and its application. Background Technology

[0002] Alginic acid derivatives, as a natural polymer material, have attracted much attention in the field of drug delivery due to their excellent biocompatibility, biodegradability, and abundant active sites. Traditional methods typically involve chemical modification, such as introducing hydrophobic groups (e.g., oleylamine, dodecyl glycidyl ether, C8-C16 straight-chain alkyl groups), to construct amphiphilic alginate derivatives, enabling them to self-assemble core-shell micelles or composite nanoparticles to encapsulate hydrophobic drugs. However, these chemical modification methods have several drawbacks: First, the hydrophobic core of the particles can efficiently encapsulate hydrophobic drugs such as doxorubicin, carotenoids, triclosan, and curcumin, significantly improving their solubility and stability. For example, Gherasim et al. used alginate hydrogel microspheres to encapsulate carotenoids, which exhibited excellent stability (>64%) during storage (30 days, 4 and 25°C). Second, by introducing stimulus-responsive groups (e.g., disulfide bonds, borate esters), intelligent drug release functions can be achieved. For example, Dhiman et al. constructed alginate derivative microgels with dual pH and redox responsiveness using 3,3'-dithiopropionylhydrazine crosslinking agents, and successfully loaded the hydrophobic drug diuron, exhibiting high encapsulation efficiency (approximately 85%). Furthermore, alginate itself possesses natural biocompatibility, degradability, and low immunogenicity, which are retained even after hydrophobic modification. For instance, liposome drugs loaded in alginate nanogels can significantly enhance their uptake in inflammatory macrophages. However, chemical modification processes typically require multiple chemical reactions (such as Schiff base-reductive amination, disulfide coupling, etc.), involving complex steps such as oxidation and reduction, which may lead to the formation of byproducts or reduce the purity of the final product. Moreover, the degree of hydrophobic modification is difficult to control; if the alginate derivative is too hydrophilic, it may cause premature disintegration of micelles in a physiological environment, while excessive hydrophobicity will reduce the water solubility of the polymer, thus limiting its drug loading capacity. Simultaneously, potential biosafety issues cannot be ignored during chemical hydrophobic modification. Although alginate itself has good biocompatibility, the new functional groups introduced through hydrophobic modification (such as oleylamine and boric acid groups), as well as potential residual oxidants and reducing agents, may affect cell viability. For example, residual 2-methylpyridine complexes may interfere with cell viability. Therefore, long-term toxicity assessment is necessary, and this process requires rigorous sample purification and toxicological testing.

[0003] To overcome the drawbacks of chemical modification, utilizing supramolecular interactions (such as host-guest recognition, hydrogen bonding, hydrophobic interactions, and metal coordination) to construct functional materials has become a milder and greener option. Supramolecular self-assembly drives the spontaneous formation of ordered structures from molecular modules through non-covalent interactions (such as hydrogen bonding, hydrophobic interactions, π-π stacking, and electrostatic interactions), avoiding complex chemical reactions and the use of toxic reagents. For example, the host-guest recognition interaction between β-cyclodextrin (β-CD) and adamantane (Ad), and the interaction of multivalent metal ions (such as Ca²⁺) can be used to construct these materials. 2+ Fe 3+ Ionic crosslinking between polymer chains and functional groups has been used to improve material properties and impart stimuli responsiveness.

[0004] However, most existing technologies utilize single or two supramolecular forces for material construction, making it difficult to integrate multiple precise and controllable response properties while achieving good stability. Therefore, how to cleverly synergistically utilize multiple non-covalent forces to construct intelligent drug delivery carriers with well-defined structures, tunable performance, and the ability to respond to various physiologically relevant signals (such as pH and light) is a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0005] This invention aims to solve the problems of complex processes and high safety risks in the construction of drug carriers by chemical methods in the prior art, as well as the technical difficulty of balancing structural stability and multiple responsiveness of carriers constructed by a single supramolecular force, and provides a pH and light-responsive supramolecular microparticle.

[0006] The technical solution adopted by this invention to solve its technical problem is:

[0007] A pH and light-responsive supramolecular microparticle, the microparticle comprising:

[0008] The polymer matrix is ​​an alginate-grafted β-cyclodextrin derivative (OSA-β-CD).

[0009] Guest molecule, wherein the guest molecule is a hydrophobic molecule containing an adamantyl group;

[0010] Multivalent metal crosslinked ions;

[0011] In this process, the multivalent metal crosslinking ions coordinate with the carboxyl groups of the polymer matrix to form an ionic crosslinking network;

[0012] Furthermore, the adamantyl group of the guest molecule associates with the β-cyclodextrin cavity of the polymer matrix through host-guest interaction, and the hydrophobic portion of the guest molecule forms a hydrophobic microdomain inside the microparticle.

[0013] The multivalent metal crosslinking ion is a ferric ion (Fe).3+ The hydrophobic molecule containing the adamantyl group is ethyl 1-adamantane carboxylate; the alginate-grafted β-cyclodextrin derivative is prepared by oxidizing sodium alginate and then reductively amination with aminated β-cyclodextrin.

[0014] This invention utilizes the synergistic effect of supramolecular forces such as hydrophobic interactions, hydrogen bonding, and metal coordination, and employs macroscopic hydrophobic modules and ion crosslinking networks to construct a well-defined Fe... 3+ -OSA-β-CD / Ad-EF supramolecular microparticles were developed to achieve controlled drug release under acidic microenvironments and light-triggered conditions. The synergistic effect of these supramolecular forces ensured that the supramolecular microparticles maintained a stable structure under different responsive conditions.

[0015] Given that the pH value of the external microenvironment can induce protonation / deprotonation of carboxyl groups in supramolecular microparticles, leading to relaxation or contraction of the cross-linked network within the supramolecular microparticles, Fe 3+ -OSA-β-CD / Ad-EF supramolecular microparticles exhibit significant pH-responsive swelling properties. Simultaneously, ultraviolet light irradiation can induce Fe... 3+ The change in the valence state of the coordination bonds triggers the disintegration effect of the ionic cross-linking network, and the supramolecular microparticle also exhibits a clear structural relaxation behavior under ultraviolet light irradiation.

[0016] Preferably, the microparticles further include a hydrophobic drug loaded within the hydrophobic microdomain. More specifically, the hydrophobic drug is curcumin. This invention utilizes curcumin (CUR), a highly representative poorly soluble drug, loaded into the hydrophobic microdomains of supramolecular microparticles to improve the solubility of the poorly soluble drug and reduce drug leakage. Under host-guest driven action, precise control of the hydrophilic-hydrophobic balance and particle size of the supramolecular microparticles is achieved by adjusting the concentration of the hydrophobic module 1-adamantane carboxylate (Ad-EF). This process induces the in-situ formation of hydrophobic microdomains and enables controlled drug release under acidic microenvironment and ultraviolet light triggering conditions.

[0017] As a preferred method, the preparation of OSA-β-CD involves dissolving oxidized alginate (OSA) with a theoretical oxidation degree of 5% to 20% in an appropriate amount of water, adding mono(6-amino-6-deoxy)-β-cyclodextrin, wherein the molar ratio of mono(6-amino-6-deoxy)-β-cyclodextrin to the oxidized uronic acid in OSA is 1:2 to 2:1; adding sodium cyanoborohydride to make the molar ratio of sodium cyanoborohydride to the oxidized uronic acid in OSA 1:1, stirring the reaction thoroughly, adding anhydrous ethanol to precipitate the reaction solution, allowing it to stand, removing the supernatant, centrifuging the remaining solid-liquid mixture, placing the precipitate obtained by centrifugation into a dialysis bag with a cutoff of 8000, dialyzing to remove small molecule impurities, and freeze-drying to obtain the product, an alginate-grafted β-cyclodextrin derivative (OSA-β-CD).

[0018] As a preferred option, Fe 3+ Cross-linked alginate-grafted β-cyclodextrin derivative / ethyl 1-adamantanecarboxylate (Fe 3+ Preparation of -OSA-β-CD / Ad-EF) supramolecular microparticles: Fe 3+ -OSA-β-CD / Ad-EF supramolecular particles are produced via Fe... 3+ The preparation process is driven by a synergistic effect of ion crosslinking and host-guest recognition. 10 mg of OSA-β-CD is dissolved in an appropriate amount of deionized water and stirred until fully dissolved. Under light-protected conditions, 100 µL of fresh FeCl3·6H2O solution with a concentration of 5.0–20.0 mg / mL is added, and the mixture is stirred (generally for 1–2 h) to ensure complete crosslinking. Subsequently, 50 µL of Ad-EF suspension with a concentration of 10–20 mg / mL is added to the system, and the mixture is stirred (generally for 2–3 h) to allow for complete complexation of host and guest molecules, forming the target product Fe. 3+ -OSA-β-CD / Ad-EF supramolecular microparticles.

[0019] Preferably, the hydrodynamic particle size of the microparticles is 100-500 nm, and the absolute value of their Zeta potential is greater than 30 mV.

[0020] A method for preparing the pH and light-responsive supramolecular microparticles, comprising the following steps:

[0021] a) Preparation of an aqueous solution of alginate-grafted β-cyclodextrin derivative (OSA-β-CD);

[0022] b) Add a solution containing multivalent metal crosslinking ions to the solution in step a) to form an ionic crosslinking network;

[0023] c) Add a hydrophobic molecule containing an adamantyl group to the system of step b), so that the hydrophobic molecule enters the interior of the ionic cross-linking network through host-guest interaction, thereby forming the supramolecular microparticles.

[0024] Preferably, the multivalent metal crosslinking ion in step b) is a ferric ion (Fe). 3+ The hydrophobic molecule containing an adamantyl group mentioned in step c) is ethyl 1-adamantane carboxylate.

[0025] Preferably, the preparation steps of the alginate-grafted β-cyclodextrin derivative are as follows:

[0026] a1) Oxidize alginic acid or its salt to obtain oxidized alginic acid;

[0027] a2) The oxidized alginate is subjected to a reductive amination reaction with the aminated β-cyclodextrin.

[0028] The application of the supramolecular microparticles described in this invention in the preparation of controlled-release formulations for pH and light-responsive drugs.

[0029] Compared with the prior art, the present invention has the following significant advantages:

[0030] 1. This invention is the first to synergistically integrate three non-covalent forces—metal ion crosslinking, host-guest recognition, and hydrophobic interaction—into a single system. By employing the ingenious method of "first building the outer frame (ion crosslinking network), then filling the inner core (host-guest association and hydrophobic microdomain formation)," it constructs structurally stable and well-defined supramolecular microparticles, overcoming the shortcomings of traditional chemical modification processes, such as complexity and low safety.

[0031] 2. The resulting microparticles integrate two independent response mechanisms. On the one hand, the carboxyl groups on the alginate backbone give it pH responsiveness, triggering drug release in the acidic microenvironment of tumors or inflammation; on the other hand, Fe... 3+ The introduction of ions gives it photoresponsiveness, allowing Fe to be triggered by external ultraviolet light. 3+ The change in valence state causes the cross-linked network to disintegrate, enabling "on-demand" release. It exhibits precise dual responsiveness.

[0032] 3. By controlling the ion crosslinking density (metal ion concentration) and the size of the hydrophobic microdomains (guest molecule concentration), the particle size, stability, and drug loading capacity of the microparticles can be easily adjusted. The prepared microparticles are uniform in size (e.g., 100-500 nm), have good stability (e.g., absolute value of Zeta potential greater than 30 mV), and can efficiently load hydrophobic drugs (e.g., curcumin), significantly improving their solubility and controlled-release performance.

[0033] 4. The microparticles are constructed based on biocompatible natural high-molecular-weight alginic acid. The entire preparation process is mild and avoids the use of toxic chemical reagents, thus exhibiting low cytotoxicity and higher safety in biomedical applications. Attached Figure Description

[0034] Figure 1 This invention provides a schematic diagram of (a) the synthesis pathway of OSA-β-CD; and (b) the synthesis pathways of SA, OA, OSA-β-CD, and β-CD-NH2. 1 (c) FT-IR spectra of SA, OA, OSA-β-CD and β-CD-NH2;

[0035] Figure 2 Fe in this invention 3+ Schematic diagram of the supramolecular self-assembly microparticle formation mechanism of OSA-β-CD / Ad-EF;

[0036] Figure 3 In this invention, (a) Fe 3+ (a) Pyrene fluorescence spectra of OSA-β-CD / Ad-EF supramolecular microparticles in aqueous solutions of different concentrations; (b) Pyrene fluorescence intensity I1 / I3 versus OSA-β-CD and Fe 3+ Relationship between -OSA-β-CD / Ad-EF supramolecular microparticle solution concentrations; Fe 3+ (c) Hydrodynamic particle size distribution, (d) Zeta potential distribution, and (e) Particle size and Zeta potential distribution after standing for 5 days for OSA-β-CD / Ad-EF supramolecular microparticles;

[0037] Figure 4 In this invention, (a) Fe 3+ XPS spectra of OSA-β-CD / Ad-EF supramolecular particles and OSA-β-CD; (b) Fe 3+ XPS Fe2p narrow scan spectrum of -OSA-β-CD / Ad-EF; (c) Fe 3+ FT-IR spectra of OSA-β-CD / Ad-EF supramolecular particles and OSA-β-CD; (d) Different Fe 3+ Concentration of Fe 3+ -OSA-β-CD / Ad-EF supramolecular particle size distribution diagram;

[0038] Figure 5 The titration curves of (a) OSA-β-CD and Ad-EF in this invention; (b) Fe 3+ -OSA-β-CD and Fe 3+ (c) Particle size distribution of OSA-β-CD / Ad-EF supramolecular particles; 3+ (c) Particle size and Zeta potential distribution curves of -OSA-β-CD / Ad-EF supramolecular microparticles, and (d) Interfacial tension variation curves;

[0039] Figure 6In this invention, (a) pH affects Fe 3+ The effect of OSA-β-CD / Ad-EF supramolecular particle size and Zeta potential; (b) Fe at pH=2.11 3+ -SOSA-β-CD / Ad-EF supramolecular particle size distribution; (c) Fe at pH=4.21 3+ -SOSA-β-CD / Ad-EF supramolecular particle size distribution; (d) Fe at pH=11.14 3+ Particle size distribution of OSA-β-CD / Ad-EF supramolecular microparticles;

[0040] Figure 7 The images shown are: (a) physical images of supramolecular self-assembled microparticle solutions before and after ultraviolet irradiation; (b) a diagram of the photoresponse mechanism of supramolecular self-assembled microparticles; (c) a diagram of the dynamic changes in particle size distribution of supramolecular self-assembled microparticles after 0-30 min of ultraviolet irradiation; and (d) a diagram of the changes in Zeta potential of supramolecular self-assembled microparticles after 0-30 min of ultraviolet irradiation.

[0041] Figure 8 Fe before and after ultraviolet irradiation in this invention 3+ (a) FT-IR spectrum, (b) XPS spectrum and (c) Fe 2p orbital XPS spectrum of OSA-β-CD / Ad-EF supramolecular microparticles;

[0042] Figure 9 The images show: (a) particle size distribution of the supramolecular self-assembled microparticles before and after drug loading and before and after UV irradiation; (b) SEM image of the drug-loaded supramolecular self-assembled microparticles; and (c) drug-loaded Fe²⁺ particles before and after UV irradiation in PBS (pH 7.4 and 5.0) at 37°C. 3+ -In vitro cumulative release curves of OSA-β-CD / Ad-EF supramolecular self-assembled microparticles and free CUR in PBS (pH 7.4); (d) Bar chart of particle size and potential changes of supramolecular self-assembled microparticles after 5 days of standing in the dark;

[0043] Figure 10 Different concentrations of Fe in this invention 3+ In vitro cytotoxicity of OSA-β-CD / Ad-EF microparticles after 24 h of culture in Raw264.7 cells. Detailed Implementation

[0044] The technical solution of the present invention will be further described in detail below through specific embodiments. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any modifications and / or alterations made to the present invention will fall within the protection scope of the present invention.

[0045] In this invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the art. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art.

[0046] Unless otherwise specified, the reagents used in the following examples can be purchased from a regular biochemical reagent store.

[0047] The OSA-β-CD of the present invention is tested for its C and N contents using a Vario EL Cube elemental analyzer (Elementar, Germany) and its degree of substitution (DS) is calculated according to formula (1).

[0048] (1)

[0049] Where α is the N / C content ratio, M C and M N These are the relative atomic masses of C and N, respectively.

[0050] The OSA-β-CD described in this invention employs FT-IR and 1 Its molecular structure was determined by 1H NMR.

[0051] The Fe of the present invention 3+ -OSA-β-CD / Ad-EF supramolecular microparticles were used to determine their critical aggregation concentration (CAC) using the pyrene fluorescent probe method. Dynamic light scattering (DLS) was used to investigate the particle size, PDI, and Zeta potential of the supramolecular self-assembled microparticles. SEM and TEM were used to detect the morphology and particle size of the supramolecular self-assembled microparticles.

[0052] The Fe of the present invention 3+ The host-guest recognition interaction between OSA-β-CD and Ad-EF supramolecular self-assembled microparticles was detected using a NANO ITC (TAInstruments, USA) microcalorimeter. 50 µL of 0.2 mM OSA-β-CD solution was loaded into a syringe, and 20 drops (2 µL each) were injected into a sample cell containing 300 µL of 0.01 mmol / L Ad-EF solution every 120 s. All experiments were conducted at a cell temperature of 25 °C and a stirring speed of 350 r / m.

[0053] The Fe of the present invention 3+-OSA-β-CD / Ad-EF supramolecular self-assembled microparticles were used as drug release media in pH 7.4 PBS and pH 5.0 PBS with 1 wt% Tween80 and 1 wt% DMSO, respectively, and simulated drug release tests were conducted at 37 °C to investigate their release performance for curcumin (CUR).

[0054] Example 1

[0055] A method for preparing pH and light-responsive supramolecular microparticles, the specific steps of which are as follows:

[0056] 1. Synthesis of OSA:

[0057] 5 g of SA was added in portions to 200 mL of deionized water and stirred for 2 h until fully dissolved. Then, 50 mL of anhydrous ethanol was added to the system, and the mixture was stirred for another 30 min to ensure thorough mixing. At room temperature, protected from light, and under a nitrogen atmosphere, 535 mg of sodium periodate was added to the system, and the mixture was stirred for 24 h, with silicone oil used to isolate it from air. After the reaction was complete, 2.5 mL of ethylene glycol was added, and the mixture was stirred for 2 h in the dark to quench the remaining sodium periodate and terminate the reaction. The system was transferred to a large beaker, and 8 g of sodium chloride was added. After stirring for 5 min, 1000 mL of anhydrous ethanol was added for alcohol precipitation. After stirring for approximately 15 min, the mixture was transferred to 4°C and allowed to stand for 12 h to precipitate. The supernatant was then removed. Finally, the remaining solid-liquid mixture was centrifuged, and the precipitate was placed in a dialysis bag with a cutoff of 8000 mg / L. Dialysis was performed for 5 days, and the precipitate was freeze-dried to obtain OSA with a theoretical oxidation degree of 10%.

[0058] 2. Preparation of alginate-grafted β-cyclodextrin derivative (OSA-β-CD):

[0059] 500 mg (approximately 2.525 mmol / L of uronic acid monomer, containing approximately 0.253 mmol of oxidized uronic acid) of OSA was dissolved in a three-necked round-bottom flask containing 50 mL of deionized water. After stirring thoroughly, 286 mg (0.2525 mmol) of mono(6-amino-6-deoxy)-β-cyclodextrin was weighed out at a molar ratio of 1:1 to the oxidized uronic acid in OSA and added to the system. After stirring at room temperature for 1 h, 15.9 mg (0.2525 mmol) of sodium cyanoborohydride was added to the above reaction system, and the reaction was stirred thoroughly at room temperature for 24 h. After the reaction was completed, 250 mL of anhydrous ethanol was added, and the mixture was stirred for 15 min to precipitate the reaction solution. The precipitate was allowed to stand for 12 h, and the supernatant was removed. Finally, the remaining solid-liquid mixture was centrifuged, and the precipitate obtained by centrifugation was placed in a dialysis bag with a cutoff of 8000. Dialysis was performed for 5 days to remove small molecule impurities. Finally, OSA-β-CD with a degree of substitution (DS) of 9.96% was obtained by freeze drying.

[0060] 3. Fe 3+ Preparation of OSA-β-CD / Ad-EF supramolecular self-assembled microparticles:

[0061] 10 mg of OSA-β-CD was dissolved in 5.0 mL of deionized water and stirred for 5 min until fully dissolved. Under light-protected conditions, 100 µL of a 10 mg / mL fresh FeCl3·6H2O solution was added, and the mixture was stirred rapidly for 1 h to allow for complete cross-linking. Subsequently, 50 µL of a 10 mg / mL Ad-EF suspension was added to the system, and the mixture was stirred for 2 h to allow for complete complexation of the host and guest molecules, forming Fe... 3+ -OSA-β-CD / Ad-EF supramolecular self-assembling microparticles.

[0062] Figure 1 (a) Schematic diagram of the synthesis pathway of OSA-β-CD; (b) SA, OA, OSA-β-CD and β-CD-NH2 1 (c) FT-IR spectra of SA, OA, OSA-β-CD, and β-CD-NH2. Figure 1 As shown in Figure a, to construct an alginate derivative with pH responsiveness and host-guest recognition characteristics, the inert dihydroxyl group on the alginate aldehyde monomer is oxidized to form an active dialdehyde group, generating OSA with an oxidation degree of 10%. During the oxidation process, some uronic acid monomers undergo skeletal structural breakage, improving molecular flexibility and facilitating subsequent grafting modification. Subsequently, OSA-β-CD with a theoretical grafting rate of 10% was prepared by reductive amination using mono(6-amino-6-deoxy)-β-cyclodextrin (β-CD-NH2) as a modifier and sodium cyanoborohydride as a reducing agent. Figure 1 b represents SA, OSA, OSA-β-CD, and β-CD-NH2. 1 The 1H NMR spectrum shows that the molecular skeleton of SA mainly exhibits proton peaks in the δ 3.3-4.2 ppm range. Oxidized OSA shows new signal peaks at δ 4.37, 4.94, and 5.04 ppm, which are attributed to the proton signals of the hemiacetal formed by the aldehyde group and adjacent hydroxyl groups, confirming the successful preparation of oxidized alginate. Compared with the starting material, OSA-β-CD shows proton signal peaks at δ 4.97 ppm and in the δ 3.50-4.00 ppm range, attributed to the β-CD group skeleton structure, confirming the successful grafting of the host molecule β-CD-NH2. Meanwhile, in... Figure 1 In c, SA, OA, and OSA-β-CD were at 2931, 1614, and 1419 cm⁻¹, respectively. -1The main characteristic absorption bands of its skeletal structure are displayed at 1714 cm⁻¹, which are attributed to the CH stretching vibration and the asymmetric and symmetric stretching vibrations of -COO- in the polysaccharide structure, respectively. Compared with SA, OSA and OSA-β-CD show absorption bands at 1714 cm⁻¹ due to the oxidation effect of sodium periodate. -1 Absorption peaks of symmetric stretching vibrations of aldehyde groups were observed in the vicinity, and these peaks exhibited lower intensity due to the ease with which the dialdehyde structure condenses to form a hemiacetal. Furthermore, OSA-β-CD showed an absorption peak at 1161 cm⁻¹. -1 The peaks at this location exhibit characteristic peaks similar to the β-CD-NH2 framework structure of the raw material. The above FT-IR and... 1 1H NMR analysis results indicate that β-CD-NH2 was successfully grafted onto the SA molecular chain under the reduction of sodium cyanoborohydride.

[0063] Figure 2 For Fe 3+ -Schematic diagram of the supramolecular self-assembly microparticle formation mechanism of OSA-β-CD / Ad-EF. (See diagram for reference.) Figure 2 As shown, OSA-β-CD aggregates in water under high concentration conditions, possessing a hydrophilic shell of β-CD groups and a hydrophilic -COO group. - Floating out in the water. Utilizing Fe 3+ Coordination between the OSA-β-CD carboxyl group and the carboxyl group constructs an ionic cross-linked network shell. Simultaneously, driven by host-guest recognition, the hydrophobic module Ad-EF enters the Fe... 3+ Crosslinked OSA-β-CD (Fe 3+ -OSA-β-CD) particles are located inside the Ad- group. The "head" Ad- group of Ad-EF enters the Fe... 3+ Within the β-CD hydrophobic cavity of -OSA-β-CD, the hydrophobic "tail" forms hydrophobic microregions within the supramolecular particles through hydrophobic association, thereby forming Fe. 3+ -OSA-β-CD / Ad-EF self-assembled supramolecular particles. By regulating Fe 3 + The concentration of Ad-EF can control the crosslinking density and hydrophilicity-hydrophobicity balance of supramolecular microparticles, and appropriate crosslinking density and hydrophilicity-hydrophobicity balance are important factors to ensure the stability of supramolecular microparticles.

[0064] Test results show that the properties of the obtained microparticles can be controlled within the particle size range of 172–342 nm by adjusting the Ad-EF concentration. These microparticles can be loaded with the hydrophobic drug curcumin (CUR), with a CUR release rate of 13%–22% within 72 h. The CUR-loaded microparticles exhibit drug release behavior that responds to both pH and light, and demonstrate good in vitro cell compatibility.

[0065] Example 2

[0066] A method for preparing pH and light-responsive supramolecular microparticles, the specific steps of which are as follows:

[0067] 1. Synthesis of OSA (Alginate): 5 g of SA was added in portions to 200 mL of deionized water and stirred for 2 h until fully dissolved. Then, 50 mL of anhydrous ethanol was added to the system, and the mixture was stirred for another 30 min to ensure thorough mixing. At room temperature, protected from light, and under a nitrogen atmosphere, 1070 mg of sodium periodate was added to the system, and the mixture was stirred for 24 h, with silicone oil used to isolate it from air. After the reaction was complete, 2.5 mL of ethylene glycol was added, and the mixture was stirred for 2 h in the dark to quench the remaining sodium periodate and terminate the reaction. The system was transferred to a large beaker, and 8 g of sodium chloride was added. After stirring for 5 min, 1000 mL of anhydrous ethanol was added for alcohol precipitation. After stirring for about 15 min, the mixture was transferred to 4°C and allowed to stand for 12 h to precipitate. The supernatant was removed. Finally, the remaining solid-liquid mixture was centrifuged, and the precipitate was placed in a dialysis bag with a cutoff of 8000 mg / L. Dialysis was performed for 5 days, and the precipitate was freeze-dried to obtain OSA with a theoretical oxidation degree of 20%.

[0068] 2. Preparation of alginate-grafted β-cyclodextrin derivative (OSA-β-CD):

[0069] 500 mg (approximately 2.525 mmol / L of uronic acid monomer, containing approximately 0.506 mmol of oxidized uronic acid) of OSA was dissolved in a three-necked round-bottom flask containing 50 mL of deionized water. After stirring thoroughly, 572 mg (0.506 mmol) of mono(6-amino-6-deoxy)-β-cyclodextrin was weighed out at a molar ratio of 1:1 to the oxidized uronic acid in OSA and added to the system. After stirring at room temperature for 1 h, 31.8 mg (0.506 mmol) of sodium cyanoborohydride was added to the above reaction system, and the reaction was stirred thoroughly at room temperature for 24 h. After the reaction was completed, 250 mL of anhydrous ethanol was added, and the mixture was stirred for 15 min to precipitate the reaction solution. The precipitate was allowed to stand for 12 h, and the supernatant was removed. Finally, the remaining solid-liquid mixture was centrifuged, and the precipitate obtained by centrifugation was placed in a dialysis bag with a cutoff of 8000. Dialysis was performed for 5 days to remove small molecule impurities. Finally, OSA-β-CD with a DS of 18.06% was obtained by freeze drying.

[0070] 3. Fe 3+ Preparation of OSA-β-CD / Ad-EF supramolecular self-assembled microparticles:

[0071] 10 mg of OSA-β-CD was dissolved in 5.0 mL of deionized water and stirred for 5 min until fully dissolved. Under light-protected conditions, 100 µL of a 5 mg / mL fresh FeCl3·6H2O solution was added, and the mixture was rapidly stirred for 1 h to allow for complete cross-linking. Subsequently, 50 µL of a 20 mg / mL Ad-EF suspension was added to the system, and the mixture was stirred for 2 h to allow for complete complexation of the host and guest molecules, forming Fe... 3+ -OSA-β-CD / Ad-EF supramolecular self-assembling microparticles.

[0072] Test results show that the particle size of the obtained microparticles can be controlled within the range of 153~317 nm, and the CUR release amount within 72 h is 11%-24%.

[0073] Example 3

[0074] A method for preparing pH and light-responsive supramolecular microparticles, the specific steps of which are as follows:

[0075] 1. Synthesis of OSA (Alginate): 5 g of SA was added in portions to 200 mL of deionized water and stirred for 2 h until fully dissolved. Then, 50 mL of anhydrous ethanol was added to the system, and the mixture was stirred for another 30 min to ensure thorough mixing. At room temperature, protected from light, and under a nitrogen atmosphere, 268 mg of sodium periodate was added to the system, and the mixture was stirred for 24 h, with silicone oil used to isolate it from air. After the reaction was complete, 2.5 mL of ethylene glycol was added, and the mixture was stirred for 2 h in the dark to quench the remaining sodium periodate and terminate the reaction. The system was transferred to a large beaker, and 8 g of sodium chloride was added. After stirring for 5 min, 1000 mL of anhydrous ethanol was added for alcohol precipitation. After stirring for about 15 min, the mixture was transferred to 4°C and allowed to stand for 12 h to precipitate. The supernatant was removed. Finally, the remaining solid-liquid mixture was centrifuged, and the precipitate was placed in a dialysis bag with a cutoff of 8000 mg / L. Dialysis was performed for 5 days, and the precipitate was freeze-dried to obtain OSA with a theoretical oxidation degree of 5%.

[0076] 2. Preparation of alginate-grafted β-cyclodextrin derivative (OSA-β-CD):

[0077] 500 mg (approximately 2.525 mmol / L of uronic acid monomer, containing approximately 0.126 mmol of oxidized uronic acid) of OSA was dissolved in a three-necked round-bottom flask containing 50 mL of deionized water. After stirring thoroughly, 143 mg (0.126 mmol) of mono(6-amino-6-deoxy)-β-cyclodextrin was weighed out at a molar ratio of 1:1 to the oxidized uronic acid in OSA and added to the system. After stirring at room temperature for 1 h, 8.0 mg (0.126 mmol) of sodium cyanoborohydride was added to the above reaction system, and the reaction was stirred thoroughly at room temperature for 24 h. After the reaction was completed, 250 mL of anhydrous ethanol was added, and the mixture was stirred for 15 min to precipitate the reaction solution. The precipitate was allowed to stand for 12 h, and the supernatant was removed. Finally, the remaining solid-liquid mixture was centrifuged, and the precipitate obtained by centrifugation was placed in a dialysis bag with a cutoff of 8000. Dialysis was performed for 5 days to remove small molecule impurities. Finally, OSA-β-CD with a DS of 4.95% was obtained by freeze drying.

[0078] 3. Fe 3+ Preparation of OSA-β-CD / Ad-EF supramolecular self-assembled microparticles:

[0079] 10 mg of OSA-β-CD was dissolved in 5.0 mL of deionized water and stirred for 5 min until fully dissolved. Under light-protected conditions, 100 µL of a 10 mg / mL fresh FeCl3·6H2O solution was added, and the mixture was stirred rapidly for 1 h to allow for complete cross-linking. Subsequently, 50 µL of a 5 mg / mL Ad-EF suspension was added to the system, and the mixture was stirred for 2 h to allow for complete complexation of the host and guest molecules, forming Fe... 3+ -OSA-β-CD / Ad-EF supramolecular self-assembling microparticles.

[0080] Test results show that the particle size of the obtained microparticles can be controlled within the range of 214~538 ​​nm, and the CUR release amount within 72 h is 9%-19.5%.

[0081] Figures 3-10 Fe prepared from Example 1 3+ The structure and properties of -OSA-β-CD / Ad-EF supramolecular microparticles were characterized. The experimental group consisted of Fe... 3+ -OSA-β-CD / Ad-EF supramolecular microparticles; control group consisted of OSA-β-CD or Fe... 3+ -OSA-β-CD particles.

[0082] Determination of Fe by pyrene fluorescent probe method 3+ The critical aggregation concentration (CAC) of OSA-β-CD / Ad-EF supramolecular microparticles was determined. First, 1.0 × 10⁻⁶ microparticles were prepared. -3A 10 µL pyrene methanol solution was accurately transferred into twelve 10 mL colorimetric tubes, and the tubes were purged with nitrogen until the methanol was completely evaporated. Then, aqueous solutions of the twelve samples with concentrations ranging from 10⁻³ to 4.0 mg / mL were added. After thorough mixing, the tubes were sonicated in a 30°C water bath for 30 min. The mixture was then equilibrated overnight at room temperature. After repeating the sonication three times, Fe²⁺ phosphate probes loaded with pyrene were prepared. 3+ -OSA-β-CD / Ad-EF supramolecular microparticle solution. Fluorescence spectroscopy was performed using an F7000 molecular fluorescence spectrometer (Hitachi, Japan) with an excitation wavelength of 335 nm, an excitation and emission slit width of 2.5 nm, an excitation voltage of 700 V, and a scanning range of 350–475 nm. Finally, a graph was plotted with the sample concentration on the x-axis and the ratio of the peak intensity of the first electron vibration peak at 373 nm to that of the third electron vibration peak at 378 nm on the y-axis. The concentration corresponding to the inflection point of the curve along the horizontal line is the Fe concentration. 3+ CAC value of -OSA-β-CD / Ad-EF supramolecular microparticles.

[0083] Furthermore, Fe was observed using a JEM2100 transmission electron microscope (TEM, JOEL, Japan). 3+ -morphology and size of OSA-β-CD / Ad-EF supramolecular particles. A small amount of sample solution was transferred using a micropipette and dropped onto a carbon-coated copper grid. The grid was then stained with a 2% (w / w) phosphotungstic acid solution, air-dried, and subjected to morphological analysis at an accelerating voltage of 200 kV.

[0084] The hydrodynamic particle size and zeta potential of supramolecular microparticles were determined using dynamic light scattering (DLS). Before testing, the particle concentration was diluted to 0.1 wt% and sonicated for 5 min. The samples were then tested using a Nano S90 Malvern Zetasizer (Malvern, UK) with a 633.8 nm He-Ne laser, a scattering angle of 90°, and 15 scans. Simultaneously, the hydrodynamic particle size and zeta potential of Fe were investigated using DLS. 3+ Concentration, Ad-EF concentration, pH value, and UV irradiation time affect Fe 3+ The influence of OSA-β-CD / Ad-EF supramolecular particle size and Zeta potential.

[0085] To investigate Fe 3+ The crosslinking between OSA-β-CD and Fe was investigated using X-ray photoelectron spectroscopy (XPS), which also examined the changes in the valence state of iron ions in the microparticles before and after ultraviolet irradiation. 3+-OSA-β-CD / Ad-EF supramolecular particles and Fe after ultraviolet irradiation 3+ Molecular valence state changes of OSA-β-CD / Ad-EF supramolecular particles. XPS spectra were obtained using an Axis UltraX-ray photoelectron spectrometer (Kratos, UK). Measurement conditions included monochromatic Al target testing, a full-spectrum scan range of 1200–0 eV with a 1.0 eV step size and an analyzer throughput of 160 eV; and a narrow scan with a 0.1 eV step size and an analyzer throughput of 20 eV. All peaks were corrected using the binding energy of the indeterminate carbon C1s peak at 284.8 eV.

[0086] Figure 3 for (a) Fe 3+ (a) Pyrene fluorescence spectra of OSA-β-CD / Ad-EF supramolecular microparticles in aqueous solutions of different concentrations; (b) Pyrene fluorescence intensity I1 / I3 versus OSA-β-CD and Fe 3+ Relationship between -OSA-β-CD / Ad-EF supramolecular microparticle solution concentrations; Fe 3+ (c) Hydrodynamic particle size distribution, (d) Zeta potential distribution, and (e) Particle size and Zeta potential distribution after 5 days of standing.

[0087] like Figure 3 As shown in a and 3b, due to the large number of hydroxyl groups and negatively charged carboxylate ions on the SA molecular chain, it easily forms strong intramolecular hydrogen bonds and classical repulsion, resulting in a relatively rigid structure. Furthermore, the outer surface of β-CD is rich in -OH groups, exhibiting strong hydrophilicity. When β-CD is grafted onto the SA molecular backbone, its hydrophilic outer edge further enhances the hydrophilicity of OSA-β-CD, making it difficult for it to self-aggregate to form typical microparticles; at this point, its CAC is approximately 1.71 mg / mL. Meanwhile, Fe... 3+ In -OSA-β-CD particles, Fe 3+ The ad-EF complex forms a network structure with the carboxylic acid groups of alginate, partially neutralizing the negative charge of SA, reducing electrostatic repulsion, and promoting the self-assembly of supramolecular particles. After being encapsulated by β-CD, the ad-EF forms hydrophobic regions, further enhancing intermolecular hydrophobic interactions. The synergistic effect of the hydrophobic microdomains and the dynamic complex network significantly reduces Fe... 3+ -OSA-β-CD / Ad-EF supramolecular microparticles CAC up to 0.31 mg / mL. Meanwhile, from Figure 3 c shows that Fe 3+ The hydrodynamic particle size of the OSA-β-CD / Ad-EF supramolecular microparticles is approximately 172.0 nm (PDI=0.239), and the particle size distribution is narrow, exhibiting good uniformity. Figure 3The figure shows that the Zeta potential of the supramolecular microparticles is approximately -35.2 mV, indicating good stability and dispersibility. Previous studies have reported that when the absolute value of the Zeta potential exceeds 30 mV, the strong electrostatic repulsion generated by the negative charge on the microparticle surface effectively resists the van der Waals attraction of the microparticles, significantly reducing their aggregation tendency. As... Figure 3 As shown in e, Fe 3+ -OSA-β-CD / Ad-EF supramolecular microparticles showed no obvious precipitation after standing for 5 days, demonstrating good static stability, which makes them suitable for applications in drug delivery, nanoengineering and other fields.

[0088] Figure 4 for (a) Fe 3+ XPS spectra of OSA-β-CD / Ad-EF supramolecular particles and OSA-β-CD; (b) Fe 3+ XPS Fe2p narrow scan spectrum of -OSA-β-CD / Ad-EF; (c) Fe 3+ FT-IR spectra of OSA-β-CD / Ad-EF supramolecular particles and OSA-β-CD; (d) Different Fe 3+ Concentration of Fe 3+ -OSA-β-CD / Ad-EF supramolecular particle size distribution diagram.

[0089] As shown in 4a, Fe 3+ XPS spectra of both OSA-β-CD / Ad-EF supramolecular particles and OSA-β-CD confirmed the presence of expected peaks in the framework structure, including Na 1s (1072.1 eV), O 1s (533.1 eV), N 1s (403.1 eV), and C 1s (286.1 eV). Furthermore, for Fe... 3+ After peak fitting of the narrow 2p scan of Fe in OSA-β-CD / Ad-EF supramolecular particles, the binding state and electronic distribution of Fe(III) can be deduced. For example... Figure 4 As shown in b, due to the -COO on the alginate molecular chain ⁻ with Fe 3+ Through ion coordination, a stable "egg-box" structure is formed, and Fe(III) remains in a high-spin state, exhibiting a complex, multiply split Fe 2p spectrum. 3+ During the drying process of the XPS sample of OSA-β-CD / Ad-EF supramolecular microparticles, the surface is oxidized, and Fe(III) is converted into Fe2O3 and Fe. 3+ It exists in two forms. Fe in the Fe 2p orbital 3+The 2p³ / 2 and 2p¹ / 2 peaks of Fe₂O₃ are located at 714.4 eV and 728.9 eV, respectively, while the 2p³ / 2 and 2p¹ / 2 peaks of Fe₂O₃ are located at 710.9 eV and 725.0 eV, respectively. Figure 4 b). Additionally, from Figure 4 The FT-IR spectrum of c shows that OSA-β-CD is at 1621.87 cm⁻¹. -1 The characteristic peak appearing at this location is its -COO ⁻ The antisymmetric stretching vibration absorption peak at 1417.45 cm⁻¹ reflects the free vibration state of -COO⁻. -1 The characteristic peak appearing at this location is its -COO ⁻ The symmetrical stretching vibration reflects the symmetrical vibration mode of -COO⁻, and at 1033.68 cm⁻¹ -1 The characteristic peak at that location is the absorption peak of the tensile vibration of COC. In contrast, Fe... 3+ In the FT-IR spectrum of -OSA-β-CD / Ad-EF supramolecular particles, due to Fe 3+ With -COO ⁻ The coordination effect enhances the strength of the CO bond, leading to -COO ⁻ The frequency of the antisymmetric stretching vibration increases, blue-shifting to 1635.71 cm⁻¹. -1 Fe 3+ The ionic crosslinking may enhance the rigidity of the OSA-β-CD molecular chain, weakening the degrees of freedom of the -COO⁻ symmetric and tensile vibrations, resulting in a redshift of the symmetric stretching and tensile vibration frequencies to 1406.36 and 1030.50 cm⁻¹, respectively. -1 The XPS and FT-IR analysis results above both indicate that Fe 3+ -OSA-β-CD / Ad-EF supramolecular particles -COO⁻ and Fe 3+ The existence of coordination. Therefore, Fe 3+ Concentration of Fe 3+ The effects of OSA-β-CD / Ad-EF supramolecular particle size and zeta potential, such as Figure 4 As shown in d. Fe 3+ At low concentrations (0.02-0.2 mg / mL), small amounts of Fe... 3+ The Fe binds to the -COO⁻ group of OSA-β-CD, forming a localized cross-linked network that causes the molecular chains to shrink, gradually reducing the particle size. At this point, a moderate cross-linking density inhibits the extension of the molecular chains, resulting in more compact nanoparticles, with the particle size decreasing from 297.4 nm to 170.1 nm. 3+ The supramolecular particle size is smallest at a concentration of 0.2 mg / mL. Further increasing the Fe concentration... 3+Excessive cross-linking at high concentrations leads to excessive rigidity within the supramolecular particles, causing them to recombine and gradually increase in size from 170.1 nm to 281.0 nm. During this process, the -COO⁻ is converted by Fe... 3+ As neutralization progresses, the negative charge on the surface of supramolecular particles decreases, and the absolute value of the Zeta potential increases with the amount of Fe. 3+ As the concentration increases, the absolute value of the Zeta potential decreases continuously, gradually increasing from -43.2 mV to -19.6 mV.

[0090] Figure 5 (a) Titration curves of OSA-β-CD and Ad-EF; (b) Fe 3+ -OSA-β-CD and Fe 3+ (c) Particle size distribution of OSA-β-CD / Ad-EF supramolecular particles; 3+ (c) Particle size and Zeta potential distribution curves of -OSA-β-CD / Ad-EF supramolecular microparticles, and (d) Interfacial tension variation curves.

[0091] like Figure 5 As shown in figure a, the interaction between OSA-β-CD and Ad-EF was analyzed using ITC. The ΔH during the inclusion process is less than zero, indicating that heat is released during host-guest binding. The ΔS is greater than zero, indicating that the self-assembly of supramolecular particles driven by host-guest recognition leads to an increase in system disorder. The calculated Gibbs free energy change (ΔG) during supramolecular self-assembly is less than zero, indicating that host-guest binding in the system is spontaneous. The dissociation constant K between OSA-β-CD and Ad-EF is... d It is 1.74 × 10 -5 The concentration of mol / L is consistent with previous reports on the binding of Ad-based derivatives to β-CD, demonstrating the formation of a stable host-guest complex between OSA-β-CD and Ad-EF. After Ad-EF is included, stable hydrophobic microdomains are formed within the self-assembled supramolecular particles. This self-assembly process exposes hydrophilic groups to form a hydrophilic shell, reducing supramolecular particle aggregation. Figure 5 As shown in b, Fe 3+ The high particle size distribution peak at 5500 nm caused by the aggregation of -OSA-β-CD particles disappears, and they recombine to form Fe particles with a more compact structure and more uniform particle size. 3+ -OSA-β-CD / Ad-EF supramolecular microparticles (hydrodynamic particle size 176.3 nm). The effect of Ad-EF concentration on Fe... 3+ The formation and size of the hydrophobic microdomains of the OSA-β-CD / Ad-EF supramolecular microparticles are directly affected. For example... Figure 5As shown in Figure c, at low concentrations (0.02-0.1 mg / mL), the cavity of β-CD selectively encapsulates the "head" -Ad group of the Ad-EF molecule, forming a stable host-guest complex. The hydrophobic "tail chain" -EF aggregates, forming hydrophobic microdomains within the supramolecular particles, promoting a more compact internal structure and reducing particle size. As the Ad-EF concentration gradually increases to 0.4 mg / mL, the unencapsulated Ad-EF molecules form hydrophobic microdomains in the solution, inducing particle aggregation (particle size increases to over 300 nm) through hydrophobic-hydrophobic interactions. Combined with the analysis of the zeta potential changes of particles at different concentrations, when Ad-EF is at low concentrations, the zeta potential of the supramolecular particles is mainly partially shielded by the negative charge on the β-CD surface, and the surface negative charge is influenced by Fe. 3+ Cooperative control, therefore Fe 3+ The zeta potential of the -OSA-β-CD / Ad-EF supramolecular microparticles fluctuates between -32.0 and -37.0 mV. When the Ad-EF concentration > 0.3 mg / mL, the zeta potential of the supramolecular microparticles rises sharply to -21.2 mV. Excess Ad-EF causes charge shielding of the supramolecular microparticles, leading to particle aggregation and compression of the electric double layer. It is well known that interfacial tension has a significant impact on the formation and stability of supramolecular microparticles. The hydrophobic effect generated by the formation of hydrophobic microdomains by Ad-EF molecules in solution leads to water molecule recombination, thereby reducing the interfacial tension. Figure 5 As shown in Figure d, with increasing Ad-EF concentration, the self-assembled supramolecular microparticles exhibit surfactant-like behavior, adsorbing onto the interface and reducing interfacial tension. When the Ad-EF concentration is 0.4 mg / mL, the liquid becomes significantly turbid, which is due to the inability of excess Ad-EF to dissolve, leading to the aggregation of supramolecular microparticles and a decrease in interfacial tension to 62.39 mN / m.

[0092] Figure 6 For (a) pH effect on Fe 3+ The effect of OSA-β-CD / Ad-EF supramolecular particle size and Zeta potential; (b) Fe at pH=2.11 3+ -SOSA-β-CD / Ad-EF supramolecular particle size distribution; (c) Fe at pH=4.21 3+ -SOSA-β-CD / Ad-EF supramolecular particle size distribution; (d) Fe at pH=11.14 3+ Particle size distribution of OSA-β-CD / Ad-EF supramolecular microparticles.

[0093] Different pH values ​​affect Fe 3+ The effects of OSA-β-CD / Ad-EF supramolecular particle size and zeta potential, such as Figure 6As shown in figure a. SA is a pH-sensitive polymer, and its uronic acid has a pK... a Approximately 3.4. For example... Figure 6 As shown in b, when the pH is below 3.0, Fe 3+ The carboxyl functional groups of the -OSA-β-CD / Ad-EF supramolecular microparticles are protonated, and the ionic cross-linking network within the supramolecular microparticles partially disintegrates, resulting in a particle size of approximately 261.0 nm and a Zeta potential of -14.7 mV. Figure 6 As shown in Figure c, when pH = 4.2, Fe 3+ The carboxylic acid groups in the OSA-β-CD / Ad-EF supramolecular microparticles are partially ionized, stabilizing their ionic crosslinking and resulting in good host-guest inclusion. Their Zeta potential is -34.1 mV, and the particle size is reduced to a minimum (approximately 172.1 nm). As the pH gradually increases from 4.2 to 8.0, the protonated carboxylic acid groups on the OSA-β-CD molecular chain gradually deprotonate and ionize into negatively charged -COO groups. - This causes the Zeta potential of supramolecular particles to gradually decrease, but electrostatic repulsion to gradually increase. Under the combined regulation of the ionic cross-linking network and hydrophobic microregions, Fe... 3+ The relaxation of the OSA-β-CD / Ad-EF molecular chain caused its particle size to increase from 172.1 nm to 193.5 nm. For example... Figure 6 As shown in d, when the pH continues to increase to around 11, the carboxylic acid groups on the OSA-β-CD molecular chain completely ionize into negatively charged -COO groups. - Electrostatic repulsion is further enhanced, and supramolecular particles swell. Simultaneously, Fe... 3+ Hydrolysis may occur, leading to the destruction of the supramolecular particle structure and the formation of clustered supramolecular particle aggregates, causing the particle size to further increase to 213.2 nm. In summary, Fe... 3+ -OSA-β-CD / Ad-EF supramolecular microparticles exhibit good pH sensitivity and have certain application potential in the field of oral drug delivery.

[0094] Controlled drug release experiment under ultraviolet light triggering conditions

[0095] CUR loaded onto Fe using emulsification 3+ -OSA-β-CD / Ad-EF supramolecular microparticles. First, a 40 mL supramolecular microparticle solution with a concentration of 2.0 mg / mL was prepared. Then, 40 mg of CUR was dissolved in 10 mL of methanol, and the solution was added dropwise to the above microparticle solution. The mixture was stirred at high speed at 40 °C for 4 h to remove methanol and promote the loading of CUR onto the microparticles. The resulting solution was sonicated for 10 min and then centrifuged at 5000 r / m for 5 min to remove unloaded CUR, thus preparing the drug-loaded Fe. 3+-OSA-β-CD / Ad-EF supramolecular microparticles. To calculate the loading rate of CUR in the drug-loaded microparticles, the CUR loaded in the drug-loaded supramolecular microparticles was extracted with ethyl acetate, and then the CUR content was determined using a U-3900 UV-Vis spectrophotometer (Hitachi, Japan). A standard curve for CUR was established based on CUR standard solutions (concentration gradient 1-20 µg / mL). The maximum absorption wavelength of CUR (λ) was determined. max The absorbance (A) was 425 nm, close to the 430 nm reported in the literature. Within the concentration range of 1-20 µg / mL, the CUR concentration (C) showed a good linear relationship with the absorbance (A), and the linear regression equation was A = 0.153C (µg / mL) + 0.033 (R² = 0.9990). Therefore, the drug loading rate (DLC) of the drug-loaded supramolecular particles can be calculated using the following formula (2).

[0096] (2)

[0097] The in vitro drug release behavior of drug-loaded supramolecular microparticles was investigated at 37°C using PBS (0.01 mol / L, pH 7.4 and 5.0) as the release medium, with 1 wt% Tween 80 and 1 wt% DMSO added to increase the solubility of CUR. Specifically, 10.0 mL of drug-loaded Fe... 3+ The OSA-β-CD / Ad-EF supramolecular microparticle solution was loaded into a dialysis bag with a molecular weight cutoff of 14,000, and then immersed in 30 mL of PBS. The entire release system was incubated in a constant-temperature water bath. At set time intervals, 2 mL of the release medium was transferred and an equal volume of fresh PBS was added to maintain a constant total volume of the release medium. The cumulative total CUR released during this time period was calculated using ultraviolet spectrophotometry (λ=425nm) in conjunction with the aforementioned standard curve. The ratio of the total release to the total drug load is the cumulative drug release rate.

[0098] The OSA-β-CD and Fe of this invention 3+ -OSA-β-CD / Ad-EF supramolecular particles and Fe after ultraviolet irradiation 3 + -OSA-β-CD / Ad-EF supramolecular particles were analyzed using an Axis Ultra X-ray photoelectron spectroscopy (Kratos, UK) to investigate the changes in their molecular valence states, thereby exploring Fe. 3+The crosslinking between the microparticles and OSA-β-CD, and the changes in the valence state of iron ions in the microparticles before and after UV irradiation were investigated. Measurement conditions included monochromatic Al target testing, a full-spectrum scan range of 1200–0 eV with a 1.0 eV step size and an analyzer throughput of 160 eV; and a narrow scan with a 0.1 eV step size and an analyzer throughput of 20 eV. All peaks were corrected using the binding energy of the indeterminate carbon C1s peak at 284.8 eV.

[0099] Figure 7 (a) Physical images of supramolecular self-assembled microparticle solutions before and after UV irradiation; (b) Schematic diagram of the photoresponse mechanism of supramolecular self-assembled microparticles; (c) Dynamic changes in particle size distribution of supramolecular self-assembled microparticles from 0 to 30 minutes of UV irradiation; (d) Changes in Zeta potential of supramolecular self-assembled microparticles from 0 to 30 minutes of UV irradiation.

[0100] like Figure 7 As shown in Figure a, the solution exhibits a significant color change before and after ultraviolet light irradiation. Combined with... Figure 7 In steps b and 7c, the dynamic process of supramolecular particle disintegration and recombination can be clearly observed. For example... Figure 7 As shown in Figure c, within the illumination range of 0 to 15 minutes, several particles with extremely different particle sizes were consistently present in the solution. It can be assumed that the system simultaneously contains Fe. 3+ and Fe 2+ The process of disintegration of old particles and formation of new particles continues. After 30 minutes of illumination, the system returns to stability, and the supramolecular particles are uniformly dispersed. It can be considered that the photoreaction within the system has ended at this point, and only Fe remains. 2+ Due to the loss of the cross-linking network, the newly formed OSA-β-CD / Ad-EF supramolecular microparticles still possess a hydrophilic outer shell and a hydrophobic inner cavity, but the binding force is weakened, resulting in significant swelling and an increase in particle size from 178.8 nm to 402.2 nm. Figure 7 As shown in d, Fe 3+ When used as a crosslinking agent, it interacts with the -COO group of alginate. ⁻ Strong electrostatic interactions are formed, giving supramolecular particles a high surface charge density. After illumination, Fe... 3+ Reduced to Fe 2+ During this process, some carboxyl groups undergo decarboxylation, weakening the electrostatic interaction and reducing the surface charge density of the particles. This leads to a continuous increase in the Zeta potential, from -40.2 mV to -13.3 mV. Furthermore, the Zeta potential change curve also shows that the Zeta potential changes rapidly during the first 5 minutes of illumination, representing the most intense stage of the photoreaction. Between 15 and 30 minutes of illumination, the Zeta potential hardly changes, indicating that the photoreaction is complete within 30 minutes, which is consistent with the particle size analysis results.

[0101] Figure 8 Fe before and after ultraviolet irradiation 3+ (a) FT-IR spectrum, (b) XPS spectrum and (c) Fe 2p orbital XPS spectrum of the OSA-β-CD / Ad-EF supramolecular microparticles.

[0102] like Figure 8 As shown in a, Fe 3+ -OSA-β-CD / Ad-EF supramolecular microparticles -COO - The groups are located at 1635.71 and 1404.82 cm⁻¹. -1 The antisymmetric and symmetric tensile vibration peaks both increased in intensity and shifted after UV irradiation, indicating that the degree of freedom of the alginate skeleton, which has lost its cross-linking constraint, increased after irradiation. - The absorption peak of the antisymmetric vibration of the functional group redshifted to 1623.59 cm⁻¹. -1 The location, and -COO - The absorption peak of the group symmetry stretching vibration is enhanced, and it blue-shifts to 1419.12 cm⁻¹. -1 Due to Fe 2+ Its coordination ability is relatively weak, and some of it is related to Fe. 3+ The release of coordinated hydroxyl or water molecules leads to an increase in the intensity of the OH stretching vibration, thus placing the OH group at 3413.56 cm⁻¹. -1 The OH stretching vibration peak at [location] redshifted to 3393.38 cm⁻¹. -1 And the peak shape becomes wider. For example Figure 8 As shown in b and 8c, after ultraviolet light irradiation, the Fe in the supramolecular particles is mainly Fe2+, and the characteristic peak of the Fe 2p orbital shows a significant shift and a decrease in peak intensity. 2+ The 2p³ / 2 and 2p¹ / 2 peaks are located at 710.4 eV and 724.0 eV, respectively. FT-IR and XPS results indicate that both the valence state of iron ions and the crosslinking state of polymer chains changed under ultraviolet light, which is consistent with the speculated photoresponse mechanism. Figure 7 b). Because Fe(II) cannot act as a crosslinking agent for OSA-β-CD polymer after light irradiation in this system, the crosslinking network in the microparticle structure gradually collapses, and the supramolecular polymer reassembles under the drive of the hydrophobic tail chain (-EF) to form a "micelle-like" OSA-β-CD / Ad-EF supramolecular shell-core structure.

[0103] Figure 9 (a) Particle size distribution of supramolecular self-assembled microparticles before and after drug loading and before and after UV irradiation; (b) SEM image of drug-loaded supramolecular self-assembled microparticles; (c) Drug-loaded Fe in PBS (pH 7.4 and 5.0) before and after UV irradiation at 37℃. 3+-In vitro cumulative release curves of OSA-β-CD / Ad-EF supramolecular self-assembled microparticles and free CUR in PBS (pH 7.4); (d) Bar chart of particle size and potential changes of supramolecular self-assembled microparticles after 5 days of standing in the dark.

[0104] like Figure 9 As shown in Figure a, the particle size of the drug-loaded supramolecular microparticles encapsulated with CUR changed significantly, increasing from 172.0 nm to 250.0 nm due to the large amount of CUR entering the hydrophobic microdomains of the supramolecular microparticles. Furthermore, since the CUR is encapsulated within the hydrophobic microdomains of the supramolecular microparticles through hydrophobic association rather than adsorbed on their surface, its Zeta potential remained almost unchanged. Subsequently, the morphology of the prepared drug-loaded supramolecular microparticles was analyzed by SEM, and the results are as follows. Figure 9 As shown in b. Fe 3+ -OSA-β-CD / Ad-EF supramolecular microparticles retain their regular nanosphere shape after being loaded with drugs and exhibit good dispersibility. Figure 9 c shows the in vitro cumulative release curves of CUR before and after UV irradiation in PBS (pH 7.4 and 5.0) at 37℃ using drug-loaded supramolecular microparticles. Compared with free CUR, the solubility and release of CUR were significantly improved after loading with supramolecular microparticles. In PBS at pH 7.4, the release of free CUR was only about 6% within 72 h, while Fe... 3+ The release of CUR in -OSA-β-CD / Ad-EF / CUR reached approximately 13%. For example... Figure 9 As shown in Figure c, by comparing the release curves at pH 7.4 and 5.0, it is easy to see that the release rate of CUR is significantly higher at pH 5.0. This may be because the carboxyl group of OSA-β-CD undergoes protonation under weakly acidic conditions, causing the supramolecular particle structure to tighten and resulting in the release of the loaded drug. This characteristic is beneficial for the targeted delivery of CUR in the slightly acidic environment of tumors (pH 6.5-7.0) or inflammatory sites (pH 5.0-6.0), improving drug bioavailability. To confirm the ability of UV light to trigger supramolecular particle drug release, the drug release behavior of drug-loaded supramolecular particles after 30 min of UV irradiation was investigated. The drug release amount of drug-loaded supramolecular particles was significantly increased within 36 h after UV irradiation. This is due to the structural transformation of the supramolecular particles after UV irradiation, Fe 3+ The disappearance of the formed cross-linked network greatly enhances the swelling capacity of the supramolecular particles, thereby accelerating drug release. For example... Figure 9As shown in Figure a, the particle size of the drug-loaded supramolecular microparticles increased from 250.0 nm to 427.8 nm after ultraviolet irradiation, and the dispersion uniformity was poor. Furthermore, static stability monitoring revealed that the particle size distribution of the drug-loaded supramolecular microparticles was uniform over 5 days, and their Zeta potential remained almost unchanged (e.g., ...). Figure 9 As shown in d), it can be inferred that drugs loaded with supramolecular microparticles also have good storage stability.

[0105] In vitro cytotoxicity test

[0106] The Fe of the present invention 3+ -OSA-β-CD / Ad-EF supramolecular self-assembled microparticles were used as mouse mononuclear macrophages (RAW264.7) as model cells, and in vitro cytotoxicity was tested using the CCK-8 assay.

[0107] Fe was assessed by in vitro culture of mouse mononuclear macrophages (RAW 264.7). 3+ Biocompatibility of OSA-β-CD / Ad-EF supramolecular microparticles. The cell culture medium consisted of 90% DMEM, 10% fetal bovine serum, 100 U / mL penicillin, and 100 μg / mL streptomycin. After resuscitation and semi-adherent proliferation in cell culture flasks, Raw264.7 cells cultured to passages 3-4 were planted at 1.2 × 10⁻⁶ cells per well. 5 Cells were seeded at a density of 100 μL into 96-well plates. One day later, 100 μL of a series of UV-sterilized microparticle solutions prepared in DMEM medium were added to achieve final concentrations of 50, 100, 200, and 400 μg / mL. A control group without added samples was used. Three wells were cultured in each group. The plates were incubated at 37 °C in a 5% CO2 incubator. After 24 h of incubation, cell viability was determined using the CCK-8 assay. 20 μL of CCK-8 reagent was added to each well, and the plates were incubated at 37 °C for 2 h. The absorbance (OD) at 450 nm was measured using a Synergy H1 multi-microplate reader (BioTek, USA), and then converted to Raw264.7 cell viability using the following formula.

[0108] Cell viability = [(A s -A b ) / (A c -A b )]×100% (3),

[0109] In the formula A s A represents the absorbance of the cell group containing the sample. c A represents the absorbance of the cell group without the sample.b The absorbance is the value of the blank background group, which contains neither sample nor cells.

[0110] Figure 10 For different concentrations of Fe 3+ In vitro cytotoxicity results of OSA-β-CD / Ad-EF microparticles on Raw264.7 cells after 24 h of culture.

[0111] like Figure 10 As shown, compared with the control group, Fe 3+ Raw264.7 cells survived and proliferated well at concentrations of 50–100 µg / mL for the OSA-β-CD / Ad-EF supramolecular microparticles, with a cell viability exceeding 80% after 24 h of culture. Therefore, these supramolecular microparticles exhibit good biocompatibility at low concentrations, making them suitable for long-term contact. However, these supramolecular microparticles showed mild cytotoxicity (74% survival rate) at a concentration of 200 µg / mL, making them unsuitable as a drug delivery material for high-dose, long-term applications. Further process optimization and modification can be implemented to ensure good biocompatibility at higher concentrations.

[0112] Effect verification

[0113] This invention prepares an alginate-grafted β-cyclodextrin derivative (OSA-β-CD) with pH responsiveness and host-guest recognition properties via an oxidation-reduction amination reaction, and uses the synthesized OSA-β-CD to manufacture supramolecular microparticles. In Fe... 3+ Under the coordination of carboxyl ions and host-guest driven mechanisms, Fe2+ with pH / light dual responsiveness was constructed using the hydrophobic building block ethyl 1-adamantane carboxylate (Ad-EF). 3+ -OSA-β-CD / Ad-EF supramolecular microparticles.

[0114] The above experimental results show that the Fe prepared by this invention 3+ The properties of OSA-β-CD / Ad-EF supramolecular microparticles (particle size, dispersion uniformity) can be easily adjusted by changing the degree of substitution of the host molecule OSA-β-CD, the concentration of the ionic crosslinking agent, and the concentration of the hydrophobic building block. The resulting supramolecular microparticles are uniform in size and have good stability (e.g., Figure 3 As shown in c and d, the particle size is approximately 172.0 nm, PDI = 0.239, and Zeta potential is approximately -35.2 mV, and it exhibits multiple responses.

[0115] Drug loading and release experiments demonstrate that, under suitable ionic crosslinking network density and hydrophobic building block concentration, the hydrophobic drug CUR can be effectively loaded into the hydrophobic microdomains of supramolecular microparticles via hydrophobic interactions, and the prepared drug-loaded supramolecular microparticles exhibit good stability. In simulated physiological environments, the drug-loaded supramolecular microparticles prepared in this invention exhibit pH- and photoresponsive drug release behaviors with different release mechanisms (e.g., ...). Figure 9 (as shown in c), and good in vitro cell compatibility.

Claims

1. A pH and light dual-responsive supramolecular microparticle, characterized in that, The microparticle comprises: a polymer matrix which is OSA-β-CD; a guest molecule which is a hydrophobic molecule comprising adamantane group; a multivalent metal cross-linking ion; wherein the multivalent metal cross-linking ion is coordinated with the carboxyl group of the polymer matrix to form an ionic cross-linking network; and the adamantane group of the guest molecule is associated with the β-cyclodextrin cavity of the polymer matrix through host-guest interaction, and the hydrophobic part of the guest molecule forms a hydrophobic microdomain inside the microparticle; The multivalent metal cross-linking ion is a trivalent iron ion (Fe 3+ ), the hydrophobic molecule containing an adamantane group is ethyl 1-adamantane carboxylate; and the alginate grafted β-cyclodextrin derivative is prepared by oxidizing sodium alginate and then performing a reductive amination reaction with an aminated β-cyclodextrin. 2.The pH and light dual-responsive supramolecular microparticle according to claim 1, wherein, The microparticle further comprises a hydrophobic drug loaded in the hydrophobic microdomain. 3.The pH and light dual-responsive supramolecular microparticle according to claim 2, characterized in that: The hydrophobic drug is curcumin. 4.The pH and light dual-responsive supramolecular microparticle of claim 1, wherein: Preparation of OSA-β-CD: Oxidized alginate salt (OSA) with a theoretical oxidation degree of 5% to 20% is dissolved in an appropriate amount of water, and mono(6-amino-6-deoxy)-β-cyclodextrin is added, wherein the molar ratio of mono(6-amino-6-deoxy)-β-cyclodextrin to oxidized uronic acid in OSA is 1:2 to 2:1; sodium cyanoborohydride is added, so that the molar ratio of sodium cyanoborohydride to oxidized uronic acid in OSA is 1:1, and after sufficient stirring and reaction, anhydrous ethanol is added to precipitate the reaction solution, and after standing, the supernatant is removed, and the remaining solid-liquid mixture is centrifuged to separate the precipitate obtained by centrifugation into a dialysis bag with a cut-off of 8000, and dialysis is performed to remove small molecular impurities, and freeze-drying is performed to obtain the product OSA-β-CD. 5.The pH and light dual-responsive supramolecular microparticle according to claim 1, wherein: Fe 3+ Cross-linked alginate grafted β-cyclodextrin derivative / ethyl 1-adamantane carboxylate (Fe 3+ Preparation of OSA-β-CD / Ad-EF supramolecular microparticles: Fe 3+ OSA-β-CD / Ad-EF supramolecular microparticles were prepared by Fe 3+ ion cross-linking and host-guest recognition synergistically driven, 10 mg of OSA-β-CD was dissolved in a suitable amount of deionized water and stirred until completely dissolved; under light-proof conditions, 100 µL of fresh FeCl3·6H2O solution with a concentration of 5.0~20.0 mg / mL was added, and stirring was performed to make it fully cross-linked; subsequently, 50 µL of Ad-EF suspension liquid with a concentration of 10~20 mg / mL was added to the system, and stirring was performed to make the host-guest molecules fully complexed, forming the target product Fe 3+ OSA-β-CD / Ad-EF supramolecular microparticles. 6.The pH and light dual-responsive supramolecular microparticle of claim 1, wherein: The hydrodynamic particle size of the microparticle is 100-500 nm, and the absolute value of its Zeta potential is greater than 30 mV.

7. A method for preparing the pH and light dual-responsive supramolecular microparticles according to claim 1, characterized in that, The method comprises the following steps: a) preparing an aqueous solution of OSA-β-CD; b) adding a solution containing a multivalent metal cross-linking ion to the solution of step a) to form an ionic cross-linking network; c) adding a hydrophobic molecule comprising an adamantane group to the system of step b) so that the hydrophobic molecule enters the interior of the ionic cross-linking network through host-guest interaction, thereby forming the supramolecular microparticle.

8. The method of claim 7, wherein, The polyvalent metal cross-linking ion in step b) is a trivalent iron ion (Fe 3+ ); the hydrophobic molecule comprising an adamantane group in step c) is ethyl 1-adamantane carboxylate.

9. The method of claim 7, wherein, The preparation steps of the OSA-β-CD are: a1) oxidizing alginate or its salt to obtain oxidized alginate; a2) subjecting the oxidized alginate to reductive amination with aminated β-cyclodextrin.

10. Use of the supramolecular microparticle of any one of claims 1-6 in the preparation of a pH and light dual-responsive drug controlled release preparation.

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