Colorful fluorescent carbon dots, colorful fluorescent hydrogel and preparation method and application of colorful fluorescent carbon dots and colorful fluorescent hydrogel

Abstract

The invention belongs to the technical field of information encryption, and provides a colorful fluorescent carbon dot, colorful fluorescent hydrogel and a preparation method and application of the colorful fluorescent carbon dot and the colorful fluorescent hydrogel. The preparation method of the colorful fluorescent carbon dots comprises the following steps: mixing biomass and a solvent, and performing hydrothermal reaction to obtain the colorful fluorescent carbon dots, the colorful fluorescent carbon dots are blue light carbon dots, green light carbon dots or yellow light carbon dots, and the biomass is Chinese violet, forsythia flower and red sophora flower. The reaction temperature of the colorful fluorescent carbon dots is milder, the reaction time is shorter, and the colorful fluorescent carbon dots conform to the green chemistry concept; the colorful fluorescent hydrogel can respond to doxycycline hydrochloride and levofloxacin, the colorful fluorescent hydrogel is stable in fluorescence color and gel structure, edited information can be stored for a long time, the information storage time is prolonged, and the information storage amount is increased.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of information encryption technology, and in particular to a multi-color fluorescent carbon dot and a multi-color fluorescent hydrogel as well as a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of information technology, data security has become a global strategic issue. Traditional encryption technology is facing the bottleneck of key vulnerability and irreversible storage medium. Physical encryption technology based on optical materials has attracted much attention due to its unique information carrying mode. However, the existing fluorescent materials generally have narrow spectral regulation range, slow environmental response and poor chemical stability, which makes it difficult to meet the demand of dynamic encryption.

[0003] Fluorescent hydrogel has unique potential in the field of information encryption due to its three-dimensional network structure which can endow the material with stimulus response characteristics. However, conventional fluorescent hydrogel usually uses organic dyes or lanthanide elements as the light source. The former has a serious photobleaching phenomenon, and the latter is limited in practical application due to heavy metal toxicity. As a new type of zero-dimensional carbon material, biomass carbon dots are green and environmentally friendly, and the raw materials are widely available and pollution-free. Through raw material selection and preparation process, multi-color fluorescence can be achieved. The rich hydroxyl and amino groups on the surface of biomass carbon dots can be covalently cross-linked with the hydrogel network, enhancing the structural stability and having excellent fluorescence tunability, environmental friendliness and surface functional modification, which is particularly suitable for building a multi-color encryption system.

[0004] Information encryption needs to solve the problems of easy counterfeiting and low security of traditional methods. At present, the intelligent response system based on fluorescent gel mostly focuses on the recognition of metal ions by fluorescent groups. For example, the quenching effect of carbon dot fluorescence on specific ions (such as Cu2 + , Fe3 + ) can be used for double verification. However, there are few reports on the use of drug molecule stimulated gel fluorescence discoloration for information anti-counterfeiting encryption.

[0005] Therefore, the development of intelligent fluorescent hydrogel materials with multiple drug molecule stimulation response, rapid and reversible discoloration, and multi-spectrum collaborative output has become the key to breaking through high-security information encryption technology. SUMMARY

[0006] The purpose of the present application is to provide a multi-color fluorescent carbon dot and a multi-color fluorescent hydrogel as well as a preparation method and application thereof in order to overcome the deficiencies of the prior art.

[0007] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions:

[0008] The present application provides a preparation method of a multi-color fluorescent carbon dot, comprising the following steps:

[0009] The biomass and the solvent are mixed and then subjected to a hydrothermal reaction to obtain the colorful fluorescent carbon dots;

[0010] The colorful fluorescent carbon dots are blue light carbon dots, green light carbon dots or yellow light carbon dots.

[0011] When the colorful fluorescent carbon dots are blue light carbon dots, the biomass is purple flowered dogwood and the solvent is water.

[0012] When the colorful fluorescent carbon dots are green light carbon dots, the biomass is forsythia flower, m-phenylenediamine is a dopant and the solvent is water.

[0013] When the colorful fluorescent carbon dots are yellow light carbon dots, the biomass is red wisteria flower, o-phenylenediamine is a dopant and the solvent is water.

[0014] Preferably, the mass-volume ratio of the purple flowered dogwood and water is 0.05-0.5g:5-25mL.

[0015] The mass-volume ratio of the forsythia flower, m-phenylenediamine and water is 0.05-0.5g:0.05-0.5g:5-25mL.

[0016] The mass-volume ratio of the red wisteria flower, o-phenylenediamine and water is 0.05-0.5g:0.05-0.5g:5-25mL.

[0017] Preferably, the temperature of the hydrothermal reaction is 80-180℃ and the time of the hydrothermal reaction is 0.5-8h.

[0018] Preferably, the reaction product obtained by the hydrothermal reaction is subjected to centrifugation, ultrafiltration and freeze-drying in sequence to obtain the colorful fluorescent carbon dots.

[0019] The centrifugation is performed at a speed of 8000-12000rpm for 20-40min.

[0020] The ultrafiltration is performed by using a filter membrane with a pore size of 0.2-0.3μm.

[0021] The freeze-drying is performed at a temperature of-75--35℃ for 8-36h.

[0022] The application further provides the colorful fluorescent carbon dots prepared by the preparation method.

[0023] The application further provides a method for preparing colorful fluorescent hydrogels from the colorful fluorescent carbon dots, comprising the following steps:

[0024] The gel matrix, the crosslinking agent, the colorful fluorescent carbon dots and water are mixed to obtain a mixed solution, and the mixed solution is subjected to ultrasonic degassing and cyclic freezing and thawing in sequence to obtain the colorful fluorescent hydrogel.

[0025] The mass-volume ratio of the gel matrix, the cross-linking agent, the colorful fluorescent carbon dots and water is 2.1-21 g: 0.1-1 g: 0.005-0.01 g: 50-150 mL.

[0026] Preferably, the gel matrix comprises polyvinyl alcohol and carboxymethyl cellulose, the polyvinyl alcohol is polyvinyl alcohol 1799 and polyvinyl alcohol 124, and the mass ratio of polyvinyl alcohol 1799, polyvinyl alcohol 124 and carboxymethyl cellulose in the gel matrix is 5-20: 5-20: 0.5-2; the cross-linking agent comprises calcium chloride.

[0027] Preferably, the mixing time is 1-2 h, the ultrasonic degassing power is 250-400 W, and the ultrasonic degassing time is 20-30 min; the number of cycles of freeze-thaw is 1-5, and in the cycle of freeze-thaw, the freezing temperature is-30 to-20 DEG C, the thawing temperature is 0-30 DEG C, the freezing time of each cycle is 2-24 h, and the thawing time of each cycle is 2-3 h.

[0028] The application further provides the colorful fluorescent hydrogel prepared by the method.

[0029] The application further provides application of the colorful fluorescent hydrogel in information encryption.

[0030] The application has the following advantages:

[0031] 1) The colorful fluorescent carbon dots of the application use edible biomass such as purpleflowered groundsel, forsythia flower and red wisteria flower as carbon sources to prepare blue light carbon dots (B-CDs), green light carbon dots (G-CDs) and yellow light carbon dots (Y-CDs), respectively, and the raw materials have the advantages of strong renewability, greenness, non-toxicity, low price and large availability, and are suitable for mass production.

[0032] 2) The reaction conditions of the colorful fluorescent carbon dots of the application are different from traditional hydrothermal synthesis methods, the reaction temperature is milder, and the reaction time is shorter, which conforms to the concept of green chemistry; the colorful fluorescent hydrogel has stable fluorescent color and stable gel structure, and the edited information can be stored for a long time, thereby prolonging the information storage time.

[0033] 3) The carbon dots prepared by the application are used as fluorescent groups and uniformly dispersed in a gel matrix composed of polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC), thereby overcoming the aggregation-induced quenching (ACQ) defect of the carbon dots and making the carbon dots have excellent photoluminescence (PL) performance; the colorful fluorescent hydrogel has a wide emission spectrum coverage range and can meet the different wavelength light quality requirements of information storage density in the blue light, green light and yellow light regions.

[0034] 4) The multi-color fluorescent hydrogel of the present application can respond to doxycycline hydrochloride and levofloxacin, and the three carbon dot gels of blue light, green light and yellow light respond to doxycycline hydrochloride to make the fluorescence emission wavelength red shift; respond to levofloxacin to make the fluorescence emission wavelength blue shift, and improve the information storage amount of the fluorescence signal coding. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 XRD patterns of the blue light carbon dots, green light carbon dots and yellow light carbon dots prepared in Examples 1-3;

[0036] Figure 2 Absorption spectrum and fluorescence spectrum of the blue light carbon dots prepared in Example 1;

[0037] Figure 3 Absorption spectrum and fluorescence spectrum of the green light carbon dots prepared in Example 2;

[0038] Figure 4 Absorption spectrum and fluorescence spectrum of the yellow light carbon dots prepared in Example 3;

[0039] Figure 5 Daylight real object pictures of the blue fluorescent hydrogel prepared in Example 4, the green fluorescent hydrogel prepared in Example 5 and the yellow fluorescent hydrogel prepared in Example 6, wherein a is the blue fluorescent hydrogel, b is the green fluorescent hydrogel and c is the yellow fluorescent hydrogel;

[0040] Figure 6 Fluorescence decryption real object pictures of the multi-color fluorescent gels prepared in Application Examples 1-3 after editing information, wherein a is the blue fluorescent hydrogel, b is the green fluorescent hydrogel and c is the yellow fluorescent hydrogel. DETAILED DESCRIPTION

[0041] The present application provides a preparation method of multi-color fluorescent carbon dots, comprising the following steps:

[0042] The biomass and the solvent are mixed and then subjected to hydrothermal reaction to obtain multi-color fluorescent carbon dots;

[0043] The multi-color fluorescent carbon dots are blue light carbon dots, green light carbon dots or yellow light carbon dots;

[0044] When the multi-color fluorescent carbon dots are blue light carbon dots, the biomass is purple flowered dogwood and the solvent is water;

[0045] When the multi-color fluorescent carbon dots are green light carbon dots, the biomass is forsythia flower, m-phenylenediamine is the dopant and the solvent is water;

[0046] When the multi-color fluorescent carbon dots are yellow light carbon dots, the biomass is red wisteria flower, o-phenylenediamine is the dopant and the solvent is water.

[0047] In the present application, the mass-volume ratio of the purple flower and water is preferably 0.05-0.5g:5-25mL, further preferably 0.1-0.4g:10-20mL, and more preferably 0.15-0.3g:13-15mL.

[0048] The mass-volume ratio of the forsythia suspensa flower, m-phenylenediamine and water is preferably 0.05-0.5g:0.05-0.5g:5-25mL, further preferably 0.1-0.4g:0.1-0.4g:10-20mL, and more preferably 0.15-0.3g:0.15-0.3g:15-16mL.

[0049] The mass-volume ratio of the forsythia suspensa flower, m-phenylenediamine and water is preferably 0.05-0.5g:0.05-0.5g:5-25mL, further preferably 0.1-0.4g:0.1-0.4g:10-20mL, and more preferably 0.15-0.3g:0.15-0.3g:15-16mL.

[0050] In the present application, the temperature of the hydrothermal reaction is preferably 80-180℃, further preferably 100-150℃, and more preferably 120-130℃, and the time of the hydrothermal reaction is preferably 0.5-8h, further preferably 2-5h, and more preferably 3h.

[0051] In the present application, the reaction product obtained by the hydrothermal reaction is preferably sequentially subjected to centrifugation, ultrafiltration and freeze-drying to obtain the colorful fluorescent carbon dots.

[0052] The rotation speed of the centrifugation is preferably 8000-12000rpm, further preferably 9000-11000rpm, and more preferably 9500-10000rpm, and the time of the centrifugation is preferably 20-40min, further preferably 25-35min, and more preferably 30min.

[0053] The pore size of the filter membrane used in the ultrafiltration is preferably 0.2-0.3μm, further preferably 0.22-0.28μm, and more preferably 0.25-0.26μm.

[0054] The temperature of the freeze-drying is preferably -75--35℃, further preferably -70--50℃, and more preferably -60℃, and the time of the freeze-drying is preferably 8-36h, further preferably 10-30h, and more preferably 15-25h.

[0055] In the present application, freezing is preferably performed before freeze-drying, and the temperature of the freezing is preferably -30--20℃, and further preferably -25℃.

[0056] The present application also provides the colorful fluorescent carbon dots prepared by the preparation method.

[0057] In the present application, the fluorescence color of the blue light carbon dots is blue, the solid powder of the blue light carbon dots is yellow-green; the fluorescence color of the green light carbon dots is green, the solid powder of the green light carbon dots is black; the fluorescence color of the yellow light carbon dots is yellow, and the solid powder of the yellow light carbon dots is yellow.

[0058] In the present application, biomass is used to prepare blue light carbon dots (B-CDs), green light carbon dots (G-CDs) and yellow light carbon dots (Y-CDs), the above-mentioned carbon dots are used as fluorescent agents, polyvinyl alcohol and carboxymethyl cellulose are used as gel matrixes, calcium chloride is used as a crosslinking agent, a mixed solution is prepared by one-pot method, and colorful fluorescent hydrogel is prepared by using a cycle freeze-thaw method.

[0059] The present application also provides a method for preparing colorful fluorescent hydrogel by using the colorful fluorescent carbon dots, comprising the following steps:

[0060] The gel matrix, the crosslinking agent, the colorful fluorescent carbon dots and water are mixed to obtain a mixed solution, and the mixed solution is sequentially subjected to ultrasonic degassing and cycle freeze-thawing to obtain the colorful fluorescent hydrogel.

[0061] The mass-volume ratio of the gel matrix, the crosslinking agent, the colorful fluorescent carbon dots and water is 2.1-21 g:0.1-1 g:0.005-0.01 g:50-150 mL.

[0062] In the present application, the mass-volume ratio of the gel matrix, the crosslinking agent, the colorful fluorescent carbon dots and water is preferably 5-16 g:0.2-0.8 g:0.006-0.009 g:70-130 mL, further preferably 8-14 g:0.4-0.6 g:0.007-0.008 g:80-120 mL, and more preferably 10-12 g:0.5 g:0.0075 g:100-110 mL.

[0063] In the present application, the gel matrix preferably comprises polyvinyl alcohol and carboxymethyl cellulose, the polyvinyl alcohol is preferably polyvinyl alcohol 1799 (PVA 1799) and polyvinyl alcohol 124 (PVA 124), and the mass ratio of PVA 1799, PVA 124 and carboxymethyl cellulose in the gel matrix is preferably 5-20:5-20:0.5-2, further preferably 8-16:8-16:0.7-1.6, and more preferably 10-12:10-12:1-1.2; and the crosslinking agent preferably comprises anhydrous calcium chloride.

[0064] In the present application, the mixing time is preferably 1-2h, further preferably 1.5h, the power of ultrasonic degassing is preferably 250-400W, further preferably 300-350W, the time of ultrasonic degassing is preferably 20-30min, further preferably 22-28min, more preferably 25min; the number of cyclic freezing and thawing is preferably 1-5 times, further preferably 2-4 times, more preferably 3 times, in the cyclic freezing and thawing, the freezing temperature is preferably-30--20℃, further preferably-28--22℃, more preferably-26--25℃, the thawing temperature is preferably 0-30℃, further preferably 5-25℃, more preferably 10-20℃, the freezing time of each time is preferably 2-24h, further preferably 5-20h, more preferably 10-15h, the thawing time of each time is preferably 2-3h, further preferably 2.5h.

[0065] The present application also provides the multicolor fluorescent hydrogel prepared by the method.

[0066] The present application also provides the application of the multicolor fluorescent hydrogel in information encryption.

[0067] In the present application, the multicolor fluorescent hydrogel is used as the "paper" carrying information, the two antibiotic drugs of doxycycline hydrochloride and levofloxacin are used as the "ink" editing information, and the ion printing technology is used to edit information on the surface of the gel; due to the stimulation response of the gel to the above-mentioned drugs, the edited information shows different fluorescent colors, and the hidden information can be clearly read under the irradiation of ultraviolet lamp, while the information cannot be recognized by naked eyes under sunlight. Using doxycycline hydrochloride solution as ink, the encrypted information edited on the multicolor fluorescent hydrogel changes to yellow fluorescent color under ultraviolet lamp; using levofloxacin solution as ink, the encrypted information edited on the multicolor fluorescent hydrogel changes to blue fluorescent color under ultraviolet lamp.

[0068] The technical solutions provided by the present application will be described in detail below in combination with examples, but they should not be understood as limiting the scope of protection of the present application.

[0069] In the examples, the purple honeysuckle, forsythia suspensa and red wisteria are taken from the campus of Liaoning University of Science and Technology.

[0070] Example 1

[0071] 0.2 g of Viola yedoensis and 10 mL of deionized water were added sequentially to a 50 mL reaction vessel and reacted at 120 °C for 2 h. The reaction product was first filtered through 40 μm filter paper to remove incompletely reacted Viola yedoensis, and then the filtrate was placed in a centrifuge tube and centrifuged at 10,000 rpm for 30 min using a high-speed centrifuge (model: SF-TGL-16M). The supernatant was ultrafiltered (pressure: 0.3 MPa) through a disposable aqueous microporous membrane (pore size: 0.22 μm; mixed fiber material) to obtain a purified blue carbon dot solution. The blue carbon dot solution was poured into a petri dish and frozen at -25 °C. The frozen carbon dots were then placed in a freeze dryer (model: LGJ-12) and freeze-dried at -70 °C for 24 h to obtain a yellow-green carbon dot solid powder.

[0072] Example 2

[0073] 0.2 g of Forsythia suspensa flowers, 0.2 g of m-phenylenediamine, and 10 mL of deionized water were added sequentially to a 50 mL reaction vessel and reacted at 120 °C for 2 h. The reaction product was first filtered through filter paper to remove incompletely reacted Forsythia suspensa flowers. The filtrate was then placed in a centrifuge tube and centrifuged at 10,000 rpm for 30 min. The supernatant was ultrafiltered through a disposable membrane (0.22 μm pore size) to obtain a purified green carbon dot solution. The green carbon dot solution was poured into a petri dish and frozen at -25 °C. The frozen carbon dots were then placed in a freeze dryer and freeze-dried at -70 °C for 24 h to obtain a black carbon dot solid powder.

[0074] Example 3

[0075] 0.2 g of Sophora japonica flowers, 0.2 g of o-phenylenediamine, and 10 mL of deionized water were sequentially added to a 50 mL reaction vessel and reacted at 120 °C for 2 h. The reaction product was first filtered through filter paper to remove incompletely reacted Sophora japonica flowers. The filtrate was then placed in a centrifuge tube and centrifuged at 10,000 rpm for 30 min. The supernatant was ultrafiltered through a disposable membrane (0.22 μm pore size) to obtain a purified yellow carbon dot solution. The yellow carbon dot solution was poured into a petri dish and frozen at -25 °C. The frozen carbon dots were then placed in a freeze dryer and freeze-dried at -70 °C for 24 h to obtain a yellow carbon dot solid powder.

[0076] The XRD patterns of the blue, green, and yellow carbon dots prepared in Examples 1-3 are shown below. Figure 1 As shown, by Figure 1 It can be seen that the XRD diffraction peaks of the blue carbon dots (B-CDs), green carbon dots (G-CDs), and yellow carbon dots (Y-CDs) prepared in Examples 1 to 3 are 22.15°, 21.92°, and 21.58°, respectively.

[0077] The absorption and fluorescence spectra of the blue carbon dots prepared in Example 1 are shown below. Figure 2 As shown, the blue carbon dots absorb ultraviolet and blue light, and are produced by... Figure 2 It is known that the optimal excitation wavelength of the blue carbon dot is 385nm, and under the excitation of 385nm ultraviolet light, its optimal emission wavelength is in the 467nm blue light region.

[0078] The absorption and fluorescence spectra of the green carbon dots prepared in Example 2 are shown below. Figure 3 As shown, the green carbon dots absorb ultraviolet and green light, and are produced by... Figure 3 It is known that the optimal excitation wavelength of the green carbon dot is 375nm, and under the excitation of 375nm ultraviolet light, its optimal emission wavelength is in the 510nm green light region.

[0079] The absorption and fluorescence spectra of the yellow carbon dots prepared in Example 3 are shown below. Figure 4 As shown, the yellow carbon dots absorb ultraviolet light and yellow light, due to... Figure 4 It can be seen that the optimal excitation wavelengths of the yellow carbon dots are 385nm and 440nm, respectively. Under the excitation of 385nm ultraviolet light, its optimal emission wavelength is in the 570nm yellow light region, and under the excitation of 440nm blue light, its optimal emission wavelength is in the 580nm yellow light region.

[0080] Example 4

[0081] 10g of polyvinyl alcohol 1799, 10g of polyvinyl alcohol 124, 1g of carboxymethyl cellulose, 1g of anhydrous calcium chloride, and 10mg of the blue carbon dots prepared in Example 1 were mixed, and then 100mL of deionized water was added. The mixture was heated and stirred at 98°C at a rate of 1000rpm for 2 hours until all raw materials were completely dissolved to obtain a gel mother liquor. The gel mother liquor was then ultrasonically degassed at a power of 300W for 30 minutes. Finally, the mother liquor was poured into a mold and frozen crosslinked at -25°C for 2 hours, and then thawed at 20°C for 2 hours. The freezing and thawing cycle was repeated 3 times to obtain a blue fluorescent hydrogel.

[0082] Example 5

[0083] The blue carbon dots prepared in Example 1 were replaced with green carbon dots prepared in Example 2, and other process conditions were the same as in Example 4, to obtain a green fluorescent hydrogel.

[0084] Example 6

[0085] The blue carbon dots prepared in Example 1 were replaced with yellow carbon dots prepared in Example 3, and the other process conditions were the same as in Example 4, resulting in a yellow fluorescent hydrogel.

[0086] Images of the blue fluorescent hydrogel prepared in Example 4, the green fluorescent hydrogel prepared in Example 5, and the yellow fluorescent hydrogel prepared in Example 6 under sunlight are shown below.Figure 5 As shown in FIG. 6, wherein a is the blue fluorescent hydrogel, b is the green fluorescent hydrogel, and c is the yellow fluorescent hydrogel. Figure 5 It can be seen that the blue fluorescent hydrogel prepared in Example 4 is transparent and colorless under sunlight, and exhibits blue fluorescence under ultraviolet light; the green fluorescent hydrogel prepared in Example 5 is brown under sunlight, and exhibits green fluorescence under ultraviolet light; and the yellow fluorescent hydrogel prepared in Example 6 is maltose color under sunlight, and exhibits yellow fluorescence under ultraviolet light.

[0087] Application Example 1

[0088] The blue fluorescent hydrogel prepared in Example 4 is used as the "paper" bearing information, and doxycycline hydrochloride is used as the "ink" editing information, and the orchid group is edited on the surface of the gel as encrypted information by using the ion printing technology. The blue fluorescent hydrogel is transparent and colorless under sunlight, and the encrypted information is decrypted and presented in blue under ultraviolet light, which can be clearly read.

[0089] Application Example 2

[0090] The green fluorescent hydrogel prepared in Example 5 is used as the "paper" bearing information, and levofloxacin is used as the "ink" editing information, and the orchid group is edited on the surface of the gel as encrypted information by using the ion printing technology. The green fluorescent hydrogel is brown under sunlight, and the encrypted information edited is a group of flowers. The encrypted information is decrypted and presented in green under ultraviolet light, which can be clearly read.

[0091] Application Example 3

[0092] The yellow fluorescent hydrogel prepared in Example 6 is used as the "paper" bearing information, and doxycycline hydrochloride is used as the "ink" editing information, and two mushrooms are edited on the surface of the gel as encrypted information by using the ion printing technology. The gel is maltose color under sunlight, and the encrypted information edited is a group of flowers. The encrypted information is decrypted and presented in yellow under ultraviolet light, which can be clearly read.

[0093] The fluorescent decryption physical pictures of the multi-color fluorescent gels prepared in Application Examples 1-3 after editing information are shown in FIG. 6. Figure 6 As shown in FIG. 6, wherein a is the blue fluorescent hydrogel, b is the green fluorescent hydrogel, and c is the yellow fluorescent hydrogel.

[0094] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which should also be considered as the protection scope of the present application.

Claims

1. A method for preparing multicolor fluorescent carbon dots, characterized in that, The preparation method comprises the following steps: The biomass and the solvent are mixed, and then a hydrothermal reaction is performed to obtain the colorful fluorescent carbon dots; The colorful fluorescent carbon dots are blue light carbon dots, green light carbon dots or yellow light carbon dots; When the colorful fluorescent carbon dots are blue light carbon dots, the biomass is purple flowered dogbane, and the solvent is water; When the colorful fluorescent carbon dots are green light carbon dots, the biomass is forsythia flower, m-phenylenediamine is a dopant, and the solvent is water; When the colorful fluorescent carbon dots are yellow light carbon dots, the biomass is red wisteria flower, o-phenylenediamine is a dopant, and the solvent is water.

2. The production method according to claim 1, characterized by, The mass-volume ratio of the purple flowered dogbane and water is 0.05-0.5 g:5-25 mL; The mass-volume ratio of the forsythia flower, m-phenylenediamine and water is 0.05-0.5 g:0.05-0.5 g:5-25 mL; The mass-volume ratio of the red wisteria flower, o-phenylenediamine and water is 0.05-0.5 g:0.05-0.5 g:5-25 mL.

3. The production method according to claim 1 or 2, characterized by, The temperature of the hydrothermal reaction is 80-180 ℃, and the time of the hydrothermal reaction is 0.5-8 h.

4. The production method according to claim 3, characterized by, The reaction product obtained by the hydrothermal reaction is sequentially subjected to centrifugation, ultrafiltration and freeze-drying to obtain the colorful fluorescent carbon dots; The centrifugation is performed at a speed of 8000-12000 rpm for 20-40 min; The ultrafiltration is performed by using a filter membrane with a pore size of 0.2-0.3 μm; The freeze-drying is performed at a temperature of-75--35 ℃ for 8-36 h.

5. The colorful fluorescent carbon dots obtained by the preparation method in any one of claims 1-4.

6. The method for preparing colorful fluorescent hydrogel by colorful fluorescent carbon dots according to claim 5, characterized in that, The preparation method comprises the following steps: The gel matrix, the crosslinking agent, the colorful fluorescent carbon dots and water are mixed to obtain a mixed solution, and the mixed solution is sequentially subjected to ultrasonic degassing and cyclic freezing and thawing to obtain the colorful fluorescent hydrogel. The mass-volume ratio of the gel matrix, the crosslinking agent, the colorful fluorescent carbon dots and water is 2.1-21 g:0.1-1 g:0.005-0.01 g:50-150 mL.

7. The method of claim 6, wherein, The gel matrix comprises polyvinyl alcohol and carboxymethyl cellulose, the polyvinyl alcohol is polyvinyl alcohol 1799 and polyvinyl alcohol 124, and the mass ratio of polyvinyl alcohol 1799, polyvinyl alcohol 124 and carboxymethyl cellulose in the gel matrix is 5-20:5-20:0.5-2; and the crosslinking agent comprises calcium chloride.

8. The method according to claim 6 or 7, characterized in that, The mixing is performed for 1-2 h, the ultrasonic degassing is performed at a power of 250-400 W for 20-30 min; the cyclic freezing and thawing is performed for 1-5 times, in which the freezing is performed at a temperature of-30--20 ℃, the thawing is performed at a temperature of 0-30 ℃, each freezing is performed for 2-24 h, and each thawing is performed for 2-3 h.

9. The colorful fluorescent hydrogel obtained by the method in any one of claims 6-8.

10. The colorful fluorescent hydrogel in claim 9 is applied to information encryption.

Images