1. A cystine-cholesterol gelator, characterized by the structural formula:

2. the method of preparing cystine cholesterol gelator according to claim 1, characterized in that it comprises the following steps:

firstly, dissolving N-1-naphthyl ethylenediamine hydrochloride in water, adding sodium hydroxide, stirring, and carrying out post-treatment to obtain N-1-naphthyl ethylenediamine;

dissolving cystine in water, adding triethylamine and di-tert-butyl dicarbonate under ice bath, stirring, and performing post-treatment and purification to obtain tert-butoxycarbonyl protected cystine;

dissolving the N-1-naphthyl ethylenediamine obtained in the first step and the cystine protected by the tert-butyloxycarbonyl obtained in the second step in N, N' -dimethylformamide, adding benzotriazole-tetramethylurea hexafluorophosphate, stirring, and performing post-treatment to obtain a cystine-naphthylethylenediamine dimer protected by the tert-butyloxycarbonyl;

fourthly, dissolving the cystine-naphthyl ethylenediamine dimer obtained in the third step into anhydrous dichloromethane, slowly dropwise adding trifluoroacetic acid in ice bath, stirring, and carrying out post-treatment to obtain the cystine-naphthyl ethylenediamine dimer without the protection of tert-butoxycarbonyl;

and fifthly, dissolving the cystine-naphthyl ethylenediamine dimer without the tert-butyloxycarbonyl protection obtained in the fourth step into anhydrous dichloromethane, adding triethylamine, stirring, adding a dichloromethane solution of cholesterol chloroformate under ice bath, and performing post-treatment to obtain the cystine-cholesterol gelator.

3. The method of claim 2, wherein the post-processing of the first step comprises: stirring at room temperature for 2h, extracting the aqueous phase with ethyl acetate for three times, combining the organic phases, drying with anhydrous sodium sulfate, filtering, and spin-drying the solvent; the molar ratio of the N-1-naphthyl ethylenediamine hydrochloride to the sodium hydroxide is 1: 2.

4. the method of claim 2, wherein the post-processing of the second step comprises: naturally raising the temperature to room temperature for reaction for 4 hours, and monitoring the reaction completion by thin-layer chromatography; spin-drying the reaction solution, dissolving the residue in ethyl acetate, washing with dilute hydrochloric acid and saturated saline respectively, separating the organic phase, drying with anhydrous sodium sulfate, filtering, spin-drying to obtain white solid, performing column chromatography separation on the white solid, and spin-steaming; the mol ratio of cystine to triethylamine to di-tert-butyl dicarbonate is 1: 2: 2.

5. the method of claim 2, wherein the post-processing of the third step comprises: stirring and reacting for 24h at room temperature, monitoring the reaction completion by thin-layer chromatography, removing the solvent by rotary evaporation, dissolving the residue in dichloromethane, washing with water and saturated saline respectively, separating the organic phase, drying with anhydrous sodium sulfate, filtering, and rotary drying to obtain light gray solid, performing column chromatography separation on the light gray solid, and rotary evaporating; the mol ratio of N-1-naphthyl ethylenediamine, tert-butoxycarbonyl protected cystine and benzotriazole-tetramethylurea hexafluorophosphate is 2: 1: 2.

6. the method of claim 2, wherein the post-processing of the fourth step comprises: naturally heating to room temperature for reaction for 12h, monitoring the reaction completion by thin-layer chromatography, spin-drying the reaction liquid, dissolving the residue in dichloromethane again, washing with saturated sodium bicarbonate solution and saturated saline solution respectively, separating the organic phase, drying with anhydrous sodium sulfate, filtering, spin-drying to obtain yellow solid, performing column chromatography separation on the yellow solid, and spin-steaming; the molar ratio of the tert-butoxycarbonyl protected cystine-naphthyl ethylenediamine dimer to trifluoroacetic acid is 1: 3.

7. the method of claim 2, wherein the post-processing of the fifth step comprises: stirring and reacting for 24h at room temperature, monitoring the reaction completion by thin-layer chromatography, washing the reaction liquid with water and saturated saline solution respectively, separating an organic phase, drying with anhydrous sodium sulfate, filtering, spin-drying to obtain a light yellow solid, carrying out column chromatography separation on the light yellow solid, and carrying out spin-steaming; the molar ratio of the cystine-naphthyl ethylenediamine dimer subjected to the removal of the tert-butyloxycarbonyl protection to the cholesteryl chloroformate is 1: 2.

8. a supramolecular gel obtained by sonicating, heating, and cooling the cystine-cholesterol gelator of claim 1 in a solvent.

9. The supramolecular gel as claimed in claim 8, wherein the supramolecular gel is prepared by the method specifically comprising: adding benzene solvent, n-propanol or cyclohexane into cystine cholesterol gelator, firstly performing ultrasonic treatment, then heating, finally cooling to room temperature, standing, inverting the test bottle, observing whether the solution flows or not, and judging whether gel is formed or not; the concentration of the cystine cholesterol gel factor is 10-25 mg/mL, the ultrasonic time is 10-20 s, the heating time is 2min, and the standing time is 10 h.

10. The supramolecular gel of claim 8 or 9 selectively recognizes Cu²⁺The use of (1).

Background

The gel shows unique advantages in many fields due to the unique rheological mechanical properties, and is widely applied to a plurality of fields such as food, cosmetics, agriculture, medicine, sewage treatment and the like at present. Among them, low molecular weight gels are widely noticed by researchers due to the advantages of easy design of molecular structure, easy regulation of performance, simple preparation method, sensitive response to external stimuli, and the like. At present, more construction elements are used for constructing low molecular weight gel, but the reasonable design of the structure of the gel factor and the accurate regulation and control of the appearance and the performance are still more difficult problems. Meanwhile, in the application process of the gel material, in addition to the need of considering the mechanical property, the environmental friendliness, biocompatibility, degradability and other properties of the gel material also need to be paid important attention. Therefore, if a gel system which takes natural small molecular compounds as raw materials and has a unique molecular structure can be designed and synthesized, the advantages of wide sources, rich content, various structures, good biocompatibility and the like of natural products are fully utilized, and the limitation of the development of current gel materials can be well solved.

Cholesterol is a very important component in the body of animals, has good biocompatibility and is closely related to physiological activities. The cholesterol structure contains a rigid structure consisting of 4 rings and a flexible tail chain, and has a strong aggregation tendency in a solvent. Cystine is the only natural amino acid containing disulfide bond in animal body, and plays an important role in the structure and function of protein in animal body. If cystine with redox response can be combined with cholesterol with good biocompatibility to obtain gel factor with unique molecular structure, the assembling process is researched, the types of supramolecular gel construction elements can be enriched, the application of natural small molecular compounds in the supramolecular field is expanded, and the life activities can be better understood. Therefore, in the invention, the cholesterol and cystine widely existing in organisms are selected as raw materials, the cystine cholesterol gelator with a unique 'butterfly' molecular structure is obtained through simple chemical modification, and the supramolecular gel property of the cystine cholesterol gelator is explored.

Disclosure of Invention

The invention aims to provide a method for synthesizing a cystine cholesterol gelator with a butterfly-shaped molecular structure and preparing supramolecular gel, so as to solve the defects in the background technology and expand the application of natural product micromolecules in the supramolecular field.

In order to achieve the above purposes, the technical scheme adopted by the invention is as follows:

a cystine cholesterol gelator, which has the following structural formula:

the structure of the cystine cholesterol gel factor simultaneously comprises a naphthalene group capable of providing pi-pi accumulation effect, an amido bond capable of providing hydrogen bond effect on cystine and a cholesterol skeleton capable of easily forming van der waals acting force, so that molecules are easily orderly arranged and assembled into a regular micro-nano structure in a solvent under the cooperative drive of pi-pi accumulation, hydrogen bond and van der waals acting force.

The invention provides a preparation method of a cystine cholesterol gelator, which comprises the following steps:

first step, synthesis of N-1-naphthylethylenediamine: dissolving N-1-naphthyl ethylenediamine hydrochloride in water, adding sodium hydroxide solid, and stirring at room temperature for 2 h. Extracting the water phase with ethyl acetate for three times, combining the organic phases, drying with anhydrous sodium sulfate, filtering, and spin-drying the solvent to obtain a yellow oily liquid of N-1-naphthyl ethylenediamine;

second step, synthesis of t-butyloxycarbonyl (Boc) protected cystine: cystine was dissolved in water and triethylamine (Et) was added under ice bath₃N) and di-tert-butyl dicarbonate (Boc)₂O) stirring, naturally raising the temperature to room temperature, reacting for 4h, and monitoring the reaction completion by Thin Layer Chromatography (TLC). The reaction solution was spin-dried, the residue was dissolved in ethyl acetate, washed with dilute hydrochloric acid and saturated brine, respectively, the organic phase was separated, dried over anhydrous sodium sulfate, filtered, and spin-dried to give a white solid. And carrying out column chromatography separation on the obtained white solid, and carrying out rotary evaporation to obtain a cystine white solid protected by Boc.

And thirdly, synthesizing a cystine-naphthyl ethylenediamine dimer protected by Boc: dissolving the N-1-naphthyl ethylenediamine obtained in the first step and the Boc protected cystine obtained in the second step in N, N-Dimethylformamide (DMF), adding benzotriazole-tetramethyluronium Hexafluorophosphate (HBTU), and stirring at room temperature for 24h to react. TLC to monitor the completion of the reaction, the solvent was removed by rotary evaporation and the residue was dissolved in dichloromethane (CH)₂Cl₂) The reaction mixture was washed with water and saturated brine, the organic phase was separated, dried over anhydrous sodium sulfate, filtered and spin-dried to give a pale gray solid. And carrying out column chromatography separation on the obtained light gray solid, and carrying out rotary evaporation to obtain Boc-protected cystine-naphthyl ethylenediamine dimer white solid.

Fourthly, synthesis of cystine-naphthyl ethylenediamine dimer without Boc protection: and (3) dissolving the white solid obtained in the third step in anhydrous dichloromethane, slowly dropwise adding trifluoroacetic acid (TFA) under ice bath, stirring, and naturally raising the temperature to room temperature for reaction for 12 hours. TLC to monitor the reaction, spin-drying the reaction solution, re-dissolving the residue in dichloromethane, washing with saturated sodium bicarbonate solution and saturated brine, separating the organic phase, drying over anhydrous sodium sulfate, filtering, and spin-drying to obtain a crude yellow solid. And carrying out column chromatography separation on the obtained yellow solid, and carrying out rotary evaporation to obtain the cystine-naphthyl ethylenediamine dimer light yellow solid without Boc protection.

Fifthly, synthesizing cystine cholesterol gelator: and (3) dissolving the light yellow solid obtained in the fourth step into anhydrous dichloromethane, adding triethylamine, stirring, adding a dichloromethane solution of cholesteryl chloroformate under ice bath, and stirring at room temperature for reaction for 24 hours. TLC monitors the reaction is complete, the reaction liquid is washed by water and saturated saline solution respectively, organic phase is separated, anhydrous sodium sulfate is dried, filtration is carried out, and light yellow solid crude product is obtained after spin-drying. And performing column chromatography separation on the obtained light yellow solid, and performing rotary evaporation to obtain a white solid of the cystine cholesterol gel factor.

On the basis of the technical scheme, in the first step, the molar ratio of the N-1-naphthyl ethylenediamine hydrochloride to the sodium hydroxide is 1: 2.

on the basis of the technical scheme, in the second step, the molar ratio of cystine, triethylamine and di-tert-butyl dicarbonate is 1: 2: 2.

on the basis of the technical scheme, in the third step, the mol ratio of N-1-naphthyl ethylenediamine, the cystine protected by Boc and HBTU is 2: 1: 2.

on the basis of the technical scheme, in the fourth step, the mole ratio of the cystine-naphthyl ethylenediamine dimer protected by Boc to trifluoroacetic acid is 1: 3.

on the basis of the technical scheme, in the fifth step, the mole ratio of the cystine-naphthyl ethylenediamine dimer subjected to Boc removal protection to the cholesterol chloroformate is 1: 2.

the invention also provides a supramolecular gel, which is obtained by self-assembling the glutamic acid cholesterol gelator in benzene solvents, n-propanol or cyclohexane and other solvents through ultrasonic treatment, heating, cooling and the like. The micro-morphology is a regular structure of nano-fiber or nano-belt and the like, and the micro-morphology is mutually staggered and wound to limit the flow of the solvent.

The invention also provides a preparation method of the supramolecular gel, which comprises the steps of adding a solvent (benzene solvent, n-propanol or cyclohexane and the like) into the cystine cholesterol gelator, carrying out ultrasonic treatment, heating, cooling to room temperature, standing, inverting a test bottle, observing whether the solution flows or not, and judging whether the gel is formed or not.

The preferable conditions of the preparation method of the supramolecular gel are as follows: the concentration of the cystine cholesterol gel factor is 10-25 mg/mL, the ultrasonic time is 10-20 s, the heating time is 2min, and the standing time is 10 h. Under these conditions, the gel formed by the molecules is stable.

The invention also provides selective Cu recognition of the supermolecular gel²⁺The use of (1).

The invention also provides a gel with reduction responsiveness, which is prepared from the cystine cholesterol gelator.

Compared with the prior art, the invention can achieve the following beneficial effects:

(1) cystine and cholesterol adopted in the preparation process of the gelator all belong to natural micromolecular compounds, and have the advantages of wide sources, low price, good biocompatibility, unique structure and the like;

(2) the whole gel factor is in a symmetrical structure and has a molecular structure similar to a butterfly shape, and the assembly process shows a unique arrangement mode;

(3) the gel factor prepared by the synthesis method not only introduces a naphthalene group capable of providing pi-pi stacking effect, but also reserves strong van der Waals effect between cholesterol skeletons and multiple hydrogen bond sites on cystine molecules, enhances non-covalent bond acting force between molecules, and shows good gel performance in various solvents;

(4) the unique molecular structure (disulfide bond, amido bond, naphthalene group, cholesterol and the like) of the gelator endows the gel system with ion selective recognition characteristic and reduction response characteristic, and the system gel has the potential of being used as a visual sensing material or a reduction response material;

(5) the preparation method of the supermolecule gel is simple and direct, is easy to operate, and the microcosmic appearances of the gels formed in different solvents are different, so that a new thought is provided for the construction of a supermolecule nano structure, and a new reference is provided for the application of a natural small molecular compound in the supermolecule field.

Drawings

The invention has the following drawings:

FIG. 1 is a photograph of the appearance of cystine cholesterol gelator gels in benzene-based solvents, where a is gel formation in ortho-xylene, b is gel formation in meta-xylene, c is gel formation in ortho-dichlorobenzene, d is gel formation in bromobenzene, e is gel formation in para-xylene, f is gel formation in mesitylene, and g is gel formation in nitrobenzene.

FIG. 2 is a scanning electron micrograph of the gel formed by cystine cholesterol gelator in o-xylene.

FIG. 3 is a scanning electron micrograph of the gel formed by cystine cholesterol gelator in meta-xylene.

FIG. 4 is a scanning electron micrograph of a gel formed from cystine cholesterol gelator in n-propanol.

FIG. 5 is a graph of the NMR spectrum of cystine cholesterol gelator in deuterated benzene solvent as a function of temperature.

FIG. 6 is a graph showing the UV absorption spectra of cystine cholesterol gelator with different metal ions added.

FIG. 7 is a fluorescence spectrum of cystine cholesterol gelator with different metal ions added.

Detailed Description

The present invention will be further described with reference to the following examples and fig. 1 to 7, which are not intended to limit the scope of the present invention.

Example 1: the synthesis of cystine cholesterol gelator with butterfly molecular structure includes the following steps:

(1) synthesis of N-1-naphthylethylenediamine (formula 1): N-1-Naphthylethylenediamine hydrochloride (600mg, 2.31mmol) was dissolved in water, and NaOH solid (185mg, 4.62mmol) was added and stirred at room temperature for 2 h. The aqueous phase was extracted three times with ethyl acetate, the organic phases were combined, dried over anhydrous sodium sulfate, filtered and rotary evaporated to give N-1-naphthylethylenediamine as a yellow oily liquid.

(2) Synthesis of t-butyloxycarbonyl (Boc) protected cystine (formula 2): cystine (500mg, 2.08mmol) was dissolved in water and Et was added under ice bath₃N and Boc₂Stirring, naturally raising the temperature to room temperature, reacting for 4h, and monitoring the reaction completion by TLC. The reaction solution was spin-dried, the residue was dissolved in ethyl acetate, washed with dilute hydrochloric acid and saturated brine, respectively, the organic phase was separated, dried over anhydrous sodium sulfate, filtered, and spin-dried to give a white solid. The resulting solid was subjected to column chromatography (eluent: V (CH))₂Cl₂)：V(CH₃OH) ═ 15:1), rotary evaporation gave Boc protected cystine as a white solid.

(3) Synthesis of Boc-protected cystine-naphthylethylenediamine dimer (formula 3) the compound represented by formula 1 (444mg, 2.5mmol) and the compound represented by formula 2 (550mg, 1.25mmol) were dissolved in DMF, HBTU (948mg, 2.5mmol) was added, and the reaction was stirred at room temperature for 24 h. TLC to monitor the reaction completion, rotary evaporation to remove the solvent and dissolving the residue in CH₂Cl₂The reaction mixture was washed with water (30 mL. times.2) and saturated brine (30mL), and the organic phase was separated, dried over anhydrous sodium sulfate, filtered, and spun-dried to give a pale gray solid. The resulting solid was subjected to column chromatography (eluent: V (CH))₂Cl₂)：V(CH₃OH) ═ 120:1), rotovapped to afford Boc protected cystine-naphthylethylenediamine dimer as a white solid.

(4) Synthesis of a deprotected cystine-naphthylethylenediamine dimer (formula 4): the compound represented by the formula 3 (296mg,0.38mmol) was dissolved in anhydrous CH₂Cl₂In the reaction solution, TFA (85. mu.L) was slowly added dropwise under ice-cooling, followed by stirring, and the temperature was naturally raised to room temperature to react for 12 hours. TLC monitoring the reaction completion of the starting material, spin-drying the reaction solution and redissolving the residue in CH₂Cl₂The reaction solution was washed with a saturated sodium bicarbonate solution (30 mL. times.2) and a saturated brine, and the organic phase was separated, dried over anhydrous sodium sulfate, filtered, and spin-dried to give a crude yellow solid. The resulting solid was subjected to column chromatography (eluent: V (CH))₂Cl₂)：V(CH₃OH) ═ 30:1), rotovapped to yield cystine-naphthylethylenediamine dimer as a pale yellow solid with Boc protection removed.

(5) Synthesis of cystine-cholesterol dimer (formula 5)

The compound represented by the formula 4 (185mg, 0.32mmol) was dissolved in anhydrous CH₂Cl₂In (1), Et is added₃N (0.2mL, excess) was stirred and the CH cholesteryl chloroformate was added under ice-bath₂Cl₂The solution (287mg,0.64mmol) was stirred at room temperature for 24 h. TLC to monitor the reaction, washing the reaction liquid with water (30mL × 2) and saturated brine, separating the organic phase, drying with anhydrous sodium sulfate, filtering, and spin-drying to obtain a light yellow solid crude product. The resulting solid was subjected to column chromatography (eluent: V (CH))₂Cl₂)：V(CH₃OH) ═ 150:1), rotary evaporation gave cystine cholesterol gelator as a white solid.

And (3) characterizing the structure of the synthesized cystine cholesterol gel factor, weighing a proper amount of the cystine cholesterol gel factor in a nuclear magnetic tube, dissolving the cystine cholesterol gel factor in a deuterated reagent, and testing the cystine cholesterol gel factor at 25 ℃ by adopting a JEOL ECA 300M nuclear magnetic resonance spectrometer. By analyzing the spectrogram, the chemical shift, integral, coupling split and chemical shift of each carbon of each hydrogen are consistent with the target molecule, which indicates that the target product is obtained.¹H-NMR(300MHz,CDCl₃):8.09(broad,2H,2×-NH-C＝O),7.76,7.42,7.30,7.27,7.22,6.57(14H,2×Ar-H),5.87,5.79(2s,2H,2×NH-CH-CH₂-S),5.29(s,2H,2×CH＝C-),4.95(broad,2H,2×Nap-NH-CH₂),4.34(m,2H,2×NH-O＝C-O-CH-),3.63(m,4H,2×Nap-NH-CH ₂-CH₂),3.44(m,4H,2×Nap-NH-CH₂-CH ₂),2.97(t,4H,2×S-CH ₂)；¹³C-NMR(75MHz,CDCl₃):171.25(O-O＝C-NH),156.53(CH₂-NH-C＝O),143.21,139.69,134.45,128.70,126.66,125.90,124.89,122.80,120.19,103.82(ArC-),123.45(CH＝C-),117.57(CH＝C-),76.00(NH-O＝C-O-CH),56.51,56.10,55.37,49.76,46.61,44.53,42.29,39.65,39.14,38.63,36.91,36.55,36.31,35.87,31.81,31.72,28.30,28.15,28.07,24.28,23.94,22.97,22.71,21.04,19.36,18.84,11.90。

Example 2: gel properties of cystine cholesterol gelator in different solvents

In order to research the gel ability of the cystine cholesterol gelator, a certain amount of cystine cholesterol gelators are respectively weighed, different solvents (benzene solvents, n-propanol, cyclohexane and the like) are respectively added, ultrasonic heating is carried out, the mixture is cooled to room temperature and kept stand for a period of time, and the gel property is observed. The results are shown in table 1:

TABLE 1 gelling Capacity of cystine-cholesterol gelators in different solvents

Wherein, TG is transparent gel; OG is an opaque gel; i, insolubilizing in a heating process; p is dissolved first and then precipitates are gradually separated out; s is still in a solution state after being cooled to room temperature. The 19 solvents are respectively measured, and the gel factor can form gel in almost all benzene solvents such as benzene, toluene, chlorobenzene and the like, and the gel has better transparency and stability (figure 1). In addition, cystine cholesterol gelator can form opaque gel in n-propanol, n-butanol, cyclohexane.

Example 3: micro-morphology of cystine cholesterol gelator formed gel in different solvents

The appearance of the gel formed in each system is observed by a Scanning Electron Microscope (SEM), and the microscopic appearance difference of the cystine cholesterol gel factor formed in different solvents is found to be large. Cystine cholesterol gelator forms gels in o-xylene and m-xylene, and crude fibers with diameters of 2-3 μm can be seen in intertwined stacked arrangement (FIGS. 2, 3); the gel formed in n-propanol, molecules aggregated to form a fiber network structure, and fibers with a diameter of about 30nm were interlaced to form a cavity with a size of 50-100nm (fig. 4). The fibers are intertwined with each other, trapping the solvent therein restricts flow, thereby forming a gel.

Example 4: temperature-variable nuclear magnetic hydrogen spectrum of gel formed by cystine cholesterol gelator in deuterated benzene solvent:

intermolecular forces during gel formation were explored by comparing nmr hydrogen spectra signals (fig. 5) of gels formed with cystine cholesterol gelators in deuterated benzene solvents at different temperatures. It was found that as the temperature increased from 25 ℃ to 55 ℃, the signal of the nuclear magnetic hydrogen spectrum changed from blunt to sharp as a whole. In addition, the chemical shifts are significantly shifted at 8.0ppm and 5.2ppm by the peak positions corresponding to the two N-H bonds. The chemical shifts of the two N-H bonds are gradually shifted to high fields along with the increase of the temperature, the N-H bonds in the molecules participate in the formation of the gel, the gel is converted into the solution due to the increase of the temperature, and the hydrogen bonds between the molecules are simultaneously broken.

Example 5: specific recognition of copper ions by cystine cholesterol gelator

The cystine cholesterol gel factor solution is respectively tested for different univalent metal ions (Li)⁺、Na⁺、K⁺、Ni⁺) And divalent metal cation (Ca)²⁺、Cd²⁺、Cu²⁺、Hg²⁺、Mg²⁺、Pb²⁺、Zn²⁺) The recognition effect of (1). It was found that the gelator was only for Cu in all metal ions²⁺Shows selective recognition, and Cu is added into ultraviolet spectrum²⁺The intensity of the absorption peak of (1) is obviously increased (figure 6), and Cu is added into the fluorescence spectrum²⁺The fluorescence intensity of the system (FIG. 7) was significantly reduced. Presumably, the amide bond and disulfide bond in the molecule are subjected to coordination and complexation with copper ions, which affects the electron distribution on naphthalene group, thereby showing specific recognition.

In addition, when Cu is added into the gel system formed by cystine cholesterol gelator²⁺When the Cu-Cu alloy is used, the gel slowly collapses and finally becomes a sol state, and other ions are added without obvious change, so that the Cu-Cu alloy is realized²⁺Is selectively identified. In contrast, the molecule without the cystine structure, which is obtained by the direct reaction of the cholesterol and the N-1-naphthyl ethylenediamine hydrochloride, has no specific recognition on metal ions, and further proves the importance of the cystine structure on ion recognition.

Example 6: reduction responsiveness of cystine cholesterol gel

The disulfide bond contained in the structure of the cystine cholesterol gelator can be changed into sulfhydryl group under the reducing condition and then changed into disulfide bond again under the oxidizing condition, and has dynamic reversibility. In order to investigate whether the gel formed by the cystine cholesterol gelator has the above-mentioned redox properties, a certain amount of reducing agent Dithiothreitol (DTT) was added to the surface of the gel formed in n-propanol solvent, and the change was observed. It is found that, as time goes on, the reducing agent gradually permeates into the gel layer, contacts with disulfide bonds in the gel structure and reduces the disulfide bonds, and the structure of part of gel factors is changed, so that the gel becomes fragile, has certain fluidity and shows the reduction responsiveness of the gel. In contrast, the control molecule, which did not contain a cystine structure, did not exhibit a reduction response property because it did not contain a disulfide bond, again demonstrating the decisive role of the cystine structure for the reduction response property.

The above embodiments are merely illustrative, and not restrictive, and those skilled in the relevant art can make various changes and modifications without departing from the spirit and scope of the invention, and therefore all equivalent technical solutions also belong to the scope of the invention.

Those not described in detail in this specification are within the skill of the art.