Biomass-based fluorescent material as well as preparation method and application thereof

Abstract

The invention discloses a biomass-based fluorescent material as well as a preparation method and application thereof. The biomass-based fluorescent material comprises a matrix material and AIE fluorescent molecules bonded on the matrix material. According to the method, the fluorescence quenching effect of the tobacco-specific nitrosamine compound on the water-soluble cellulose derivative is utilized, the tobacco-specific nitrosamine compound with extremely low content in a normal tobacco product cannot be identified, and a counterfeit product generates macroscopic fluorescence change due to overhigh concentration; therefore, the authenticity of the tobacco material can be quickly and visually identified. Through the enrichment effect of the fluorescent cellulose microspheres and the electrostatic interaction between the fluorescent cellulose microspheres and to-be-detected molecules, a portable detection system capable of rapidly, sensitively and repeatedly identifying the authenticity of the tobacco is provided on the basis of the specific quenching of the nitrosamine compound specific to the tobacco on the fluorescence of the cellulose microspheres.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of tobacco anti-counterfeiting technology, and particularly relates to a biomass-based fluorescent material and a preparation method and application thereof. BACKGROUND

[0002] Tobacco products have the characteristics of high added value and rapid circulation, which makes the phenomenon of manufacturing and selling fake cigarettes persistent. At present, cigarette manufacturers have adopted various anti-counterfeiting measures, such as two-dimensional codes, optically variable inks, fluorescent inks, NFC, etc. However, such packaging anti-counterfeiting measures are often universal and cannot fundamentally prevent fake cigarettes from entering the market.

[0003] Tobacco-specific nitrosamine compounds (TSNAs) are an important class of substances in tobacco. Studies have shown that the content of TSNAs in regular cigarettes ranges from 85 ng / g to 12.66 μg / g, of which the content of flue-cured tobacco is generally less than 0.5 μg / g, and the content of mixed / cigar-type tobacco can reach 3-12 μg / g (Relationship between the content of tobacco-specific nitrosamines and precursors in tobacco and its products in China, China Tobacco Journal, March 2002, Vol. 8, No. 1). Fake cigarettes may use low-grade, moldy, or discarded tobacco leaves or stems, or even add non-tobacco plant materials. The content of nitrate and alkaloid precursors in the raw materials may be high and unstable, and the production process is rough and lacks strict control. In order to quickly produce or simulate the taste of real cigarettes, abnormally high temperatures or improper fermentation conditions may be used. In addition, fake cigarettes often use excessive flavors, spices, and sugar materials (such as glycerol and propylene glycol) to mask the odor and irritation of inferior raw materials, and even add unknown chemicals to simulate the taste of real cigarettes. Therefore, the content of TSNAs in fake cigarettes often exceeds the standard, and this difference becomes an important breakthrough in the identification of the authenticity of tobacco.

[0004] At present, the detection methods of TSNAs in tobacco products include liquid chromatography-tandem mass spectrometry, gas chromatography-thermal energy analysis, and ultra-high performance liquid chromatography-time-of-flight mass spectrometry. These detection methods require complex sample processing and detection processes, and have low detection efficiency, which makes it difficult to be used for rapid identification of the authenticity of tobacco products.

[0005] Therefore, how to provide a material that can quickly and effectively determine the content of TSNAs in tobacco and tobacco products has become a technical problem that needs to be solved in the field. SUMMARY

[0006] An object of the present application is to provide a new technical solution of a biomass-based fluorescent material for detecting tobacco-specific nitrosamine compounds in tobacco and tobacco products.

[0007] According to a first aspect of the present application, a biomass-based fluorescent material is provided.

[0008] The biomass-based fluorescent material comprises a matrix material and AIE fluorescent molecules bonded to the matrix material. The matrix material is selected from at least one of starch, chitosan, chitin, lignin, cellulose ester, cellulose ether, and microcrystalline cellulose. The AIE fluorescent molecules are selected from at least one of thiophene and its derivatives, styrene derivatives, pyrrole derivatives, fluorene and its derivatives, carbazole derivatives, thiophene compounds, and naphthalimide compounds. The degree of substitution of the AIE fluorescent molecules in the biomass-based fluorescent material is 0.0001-1.0.

[0009] According to a second aspect of the present invention, a method for preparing a biomass-based fluorescent material is provided, comprising the following steps:

[0010] (1) Dissolve and disperse the matrix material in an organic solvent to obtain a homogeneous solution of the matrix material;

[0011] (2) Disperse the AIE fluorescent molecules into a homogeneous solution of the matrix material and carry out the reaction;

[0012] (3) The product obtained in step (2) is purified and dried to obtain biomass-based fluorescent material.

[0013] Optionally, in step (2), the mass ratio of the matrix material to the AIE fluorescent molecules is 1:(0.01-5).

[0014] Optionally, the reaction in step (2) is an etherification reaction, with a reaction temperature of 40-100℃ and a reaction time of 4-72h.

[0015] According to a third aspect of the present invention, a biomass-based fluorescent material is provided.

[0016] The biomass-based fluorescent material comprises a matrix material, AIE fluorescent molecules bonded to the matrix material, and charged molecules bonded to the matrix material. The matrix material is selected from at least one of starch, chitosan, chitin, lignin, cellulose esters, cellulose ethers, and microcrystalline cellulose. The AIE fluorescent molecules are selected from at least one of thiophene and its derivatives, styrene derivatives, pyrrole derivatives, fluorene and its derivatives, carbazole derivatives, thiophene compounds, and naphthalimide compounds. The charged molecules are selected from at least one of quaternary ammonium salts, sulfonates, carboxylates, and betaine compounds.

[0017] According to a fourth aspect of the present invention, a method for preparing a biomass-based fluorescent material is provided, comprising the following steps:

[0018] (1) Dissolve and disperse the matrix material in the ionic liquid to obtain a homogeneous and transparent clear solution;

[0019] (2) dispersing the solution obtained in step (1) into an organic solvent, obtaining microspheres by coaxial airflow shearing method, and obtaining biomass-based hydrogel microspheres by regeneration with a precipitating agent and washing with deionized water;

[0020] (3) placing the biomass-based hydrogel microspheres in an organic solvent for solvent exchange, adding an AIE fluorescent molecule and a charged molecule, and performing a reaction;

[0021] (4) performing screening, purification and solvent replacement on the product obtained in step (3), or performing tert-butyl alcohol replacement and freeze-drying on the product obtained in step (3), to obtain a biomass-based fluorescent material.

[0022] Optionally, the ionic liquid in step (1) is an organic molten salt formed by a cation and an anion, and having a melting point lower than 100°C, wherein the cation is at least one of 1-ethyl-3-methylimidazolium, 1-propyl-3-methylimidazolium, 1-allyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, N-ethylpyridinium, N-butylpyridinium and N-hexylpyridinium, and the anion is at least one of chloride, bromide, formate, acetate, propionate, butyrate and methyl phosphate.

[0023] Optionally, the reaction in step (3) is an etherification reaction or an esterification reaction, the reaction temperature is 40-100°C, and the reaction time is 4-72h.

[0024] According to a fifth aspect of the present application, a biomass-based fluorescent material is provided, which is used to identify the authenticity of a tobacco material by the fluorescence quenching effect of the biomass-based fluorescent material on nitrosamine compounds in the tobacco material.

[0025] Optionally, the application comprises the following steps:

[0026] (1) grinding tobacco shreds in a tobacco product to be tested into powder, soaking the powder in an ammonium acetate aqueous solution, and oscillating and extracting for a period of time;

[0027] (2) centrifuging the solution obtained in step (1) to obtain supernatant;

[0028] (3) filtering the supernatant obtained in step (2) through a water-based filter membrane, and obtaining an extraction liquid by constant volume;

[0029] (4) adding a biomass-based fluorescent material to the extraction liquid, and identifying the authenticity of the tobacco product by the fluorescence quenching effect of nitrosamine on the biomass-based fluorescent material.

[0030] The biomass-based fluorescent material provided by this invention utilizes the good water solubility of cellulose ether derivatives. By bonding AIE fluorescent groups to their molecular chains, water-soluble cellulose derivatives are obtained.

[0031] This invention also utilizes the homogeneous dissolution of cellulose in ionic liquids and its regeneration in poor solvents to provide cellulose hydrogel microspheres with controllable spherical diameters at the micrometer scale, and utilizes the heterogeneous reaction of hydrogel microspheres with fluorescent groups and charged molecules to provide biomass-based fluorescent materials of positively charged fluorescent cellulose microspheres.

[0032] This invention utilizes the fluorescence quenching effect of tobacco-specific nitrosamine compounds on water-soluble cellulose derivatives. Because the extremely low concentration of tobacco-specific nitrosamine compounds in genuine tobacco products is undetectable, while counterfeit products exhibit visible fluorescence changes due to excessively high concentrations, this invention provides a rapid and visually identifiable method for identifying genuine tobacco materials. Through the enrichment effect of fluorescent cellulose microspheres and their electrostatic interaction with the target molecules, and based on the specific quenching of the fluorescence of cellulose microspheres by tobacco-specific nitrosamine compounds, this invention offers a portable detection system capable of rapidly, sensitively, and repeatedly identifying genuine tobacco products.

[0033] This invention reconstructs the anti-counterfeiting logic of tobacco products through the chemical response of biomaterials, binding product ingredients with anti-counterfeiting labels to form a "product-label" interactive verification mechanism. Compared with traditional identification methods, this invention has a triple breakthrough of dynamic response, user-friendliness, and difficulty in replication, providing the industry with an anti-counterfeiting path that is both economical and reliable.

[0034] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0035] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0036] Figure 1 The cellulose-based fluorescent material HPC-TPE prepared in Example 1 1 H NMR and FTIR spectra: (a) 1 (a) HNMR image, (b) FTIR image.

[0037] Figure 2 The MCC microspheres, MCC-TPE microspheres, and MCC-TPE-N microspheres prepared in Examples 2-4 + FTIR plot of microspheres.

[0038] Figure 3 The MCC microspheres prepared in Example 2 and the MCC-TPE-N prepared in Example 4+ Scanning electron microscope image of microspheres.

[0039] Figure 4 The image shows the spectra of different concentrations of NNK aqueous solution added to the HPC-TPE suspension in Example 5.

[0040] Figure 5 In Example 6, MCC-TPE-N + Spectra of microspheres after being immersed in NNK aqueous solutions of different concentrations.

[0041] Figure 6 In Example 6, MCC-TPE-N + Fluorescence micrographs of microspheres before and after immersion in 10 μM NNK aqueous solution. Detailed Implementation

[0042] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0043] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0044] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0045] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0046] This invention utilizes the good water solubility of different biomass or biomass derivatives to introduce aggregation-induced emission (AIE) fluorescent groups into the molecular structure of biomass or biomass derivatives, providing a water-soluble biomass-based fluorescent material that can sensitively detect nitro compound residues in tobacco and tobacco products.

[0047] The biomass-based fluorescent material provided by this invention includes a matrix material and AIE fluorescent molecules bonded to the matrix material. The matrix material is selected from at least one of starch, chitosan, chitin, lignin, cellulose ester, cellulose ether, and microcrystalline cellulose. The AIE fluorescent molecules are selected from at least one of thiophene and its derivatives, styrene derivatives, pyrrole derivatives, fluorene and its derivatives, carbazole derivatives, thiophene compounds, and naphthalimide compounds. The degree of substitution of the AIE fluorescent molecules in the biomass-based fluorescent material is 0.0001-1.0.

[0048] The base material is at least one of biomass and biomass derivatives. For example, the base material can be selected from at least one of starch, chitosan, chitin, lignin, cellulose ester, cellulose ether and microcrystalline cellulose (MCC). Among them, the cellulose ester can be selected from at least one of cellulose acetate, cellulose acetate butyrate, cellulose propionate, cellulose butyrate, cellulose nitrate, cellulose sulfate, cellulose benzoate and cellulose cinnamate; the cellulose ether can be selected from at least one of methyl cellulose, ethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose and hydroxypropyl cellulose (HPC); the lignin can be selected from at least one of alkali lignin, sulfate lignin, solvent lignin, acid hydrolysis lignin and enzymatic lignin. Exemplarily, the base material is HPC.

[0049] The AIE fluorescent molecule can be selected from at least one of thiazole and its derivatives, styrene derivatives, pyrrole derivatives, fluorene and its derivatives, carbazole derivatives, thiophene compounds and naphthalene diimide compounds. Among them, the thiazole and its derivatives can be selected from at least one of tetraphenylthiazole, hexaphenylthiazole and 2,3,4,5-tetra(4-methoxyphenyl)thiazole; the styrene derivatives can be selected from at least one of 1,1,2,2-tetraphenyl ethylene, nitrile substituted stilbene, 4,4'-diboronic acid-based tetraphenyl ethylene and tetra(4,4',4'',4'''-allyloxy)tetraphenyl ethylene; the pyrrole derivatives can be selected from at least one of tetraphenylpyrrole and bispyrrolyl ethylene; the fluorene and its derivatives can be selected from at least one of 9,9-diphenylfluorene and fluorene-thiophene copolymer; the carbazole derivatives can be selected from at least one of triphenylcarbazole and carbazole-styrene conjugated molecules; the thiophene compounds can be selected from at least one of dibenzothiophene and its derivatives and cyclooctatetra-thiophene and its derivatives. Exemplarily, the AIE fluorescent molecule is 1-(4-bromomethylphenyl)-1,1,2-triphenyl ethylene (TPE-Br).

[0050] The degree of substitution of the AIE fluorescent molecule in the biomass-based fluorescent material is preferably 0.01-0.5.

[0051] The present application also provides a preparation method of the biomass-based fluorescent material, comprising the following steps:

[0052] (1) dissolving and dispersing the base material into an organic solvent to obtain a uniform solution of the base material.

[0053] (2) dispersing the AIE fluorescent molecule into the uniform solution of the base material and performing a reaction.

[0054] The mass ratio of the base material to the AIE fluorescent molecule in step (2) is 1:(0.01-5), preferably 1:(0.05-1).

[0055] The reaction in step (2) is an etherification reaction, the reaction temperature is 40-100°C, preferably 80°C, and the reaction time is 4-72h, preferably 12h.

[0056] (3) purifying and drying the product obtained in step (2) to obtain the biomass-based fluorescent material. The yield of the biomass-based fluorescent material is 65-85%.

[0057] The purification in step (3) includes organic solvent washing or dialysis.

[0058] In specific implementation, the biomass-based fluorescent material can be prepared as follows:

[0059] 1) dispersing HPC in dimethyl sulfoxide (DMSO) and heating to 60-100°C (for example, 70-90°C, and exemplarily 80°C) to stir until completely dissolved to obtain a DMSO solution of HPC;

[0060] 2) dissolving TPE-Br and sodium hydroxide in deionized water, and then adding dropwise into the DMSO solution of HPC;

[0061] 3) reacting the mixture obtained in step 2) at 60-100°C (for example, 70-90°C, and exemplarily 80°C) for 8-24 hours (for example, 12 hours), after the reaction is completed, dialyzing the solution with a mixed solution of deionized water and DMF (1:1) as the outer liquid, and then dialyzing with deionized water as the outer liquid, after the inner and outer liquids are balanced, concentrating the liquid in the dialysis bag, and then freeze-drying to obtain the biomass-based fluorescent material.

[0062] The application also provides a biomass-based fluorescent material (also referred to as a biomass-based charged fluorescent microsphere), which comprises a base material, AIE fluorescent molecules bonded to the base material, and charged molecules bonded to the base material, wherein the base material is selected from at least one of starch, chitosan, chitin, lignin, cellulose ester, cellulose ether and microcrystalline cellulose, the AIE fluorescent molecules are selected from at least one of thienyl and its derivatives, styrene derivatives, pyrrole derivatives, fluorene and its derivatives, carbazole derivatives, thiophene compounds and naphthalene diimide compounds, and the charged molecules are selected from at least one of quaternary ammonium salts, sulfonate salts, carboxylate salts and betaine compounds.

[0063] The base material is at least one of biomass and biomass derivatives. For example, the base material can be at least one of starch, chitosan, chitin, lignin, cellulose ester, cellulose ether and microcrystalline cellulose (MCC). The cellulose ester can be at least one of cellulose acetate, cellulose acetate butyrate, cellulose propionate, cellulose butyrate, cellulose nitrate, cellulose sulfate, cellulose benzoate and cellulose cinnamate; the cellulose ether can be at least one of methyl cellulose, ethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose and HPC; the lignin can be at least one of alkali lignin, kraft lignin, solvent lignin, acid hydrolysis lignin and enzymatic lignin. Exemplarily, the base material is MCC.

[0064] The AIE fluorescent molecule can be at least one of thiazole and its derivatives, styrene derivatives, pyrrole derivatives, fluorene and its derivatives, carbazole derivatives, thiophene compounds and naphthalene diimide compounds. The thiazole and its derivatives can be at least one of tetraphenylthiazole, hexaphenylthiazole and 2,3,4,5-tetra(4-methoxyphenyl)thiazole; the styrene derivatives can be at least one of 1,1,2,2-tetraphenyl ethylene, nitrile substituted stilbene, 4,4'-diboronic acid-based tetraphenyl ethylene and tetra(4,4',4'',4'''-allyloxy)tetraphenyl ethylene; the pyrrole derivatives can be at least one of tetraphenylpyrrole and bispyrrolyl ethylene; the fluorene and its derivatives can be at least one of 9,9-diphenylfluorene and fluorene-thiophene copolymer; the carbazole derivatives can be at least one of triphenylcarbazole and carbazole-styrene conjugated molecules; the thiophene compounds can be at least one of dibenzothiophene and its derivatives and cyclooctatetra-thiophene and its derivatives. Exemplarily, the AIE fluorescent molecule is TPE-Br.

[0065] The charged molecule can be at least one of quaternary ammonium salt, sulfonate, carboxylate and betaine compounds. The quaternary ammonium salt compound can be at least one of tetramethylammonium chloride, cetyltrimethylammonium bromide, benzyltrimethylammonium chloride, (3-carboxypropyl)trimethylammonium chloride (N + -COOH), sodium dodecyl sulfate and perfluorooctanesulfonic acid; the carboxylate compound can be at least one of sodium polyacrylate and ethylenediaminetetraacetic acid; the betaine compound can be at least one of cocamidopropyl betaine and 3-(N,N-dimethyl dodecyl ammonium) propanesulfonate. Exemplarily, the charged molecule is N + -COOH.

[0066] The present application also provides a preparation method of the biomass-based fluorescent material (also referred to as biomass-based charged fluorescent microspheres), which comprises the following steps:

[0067] (1) Dissolve and disperse the base material into the ionic liquid to obtain a uniform and transparent clear solution.

[0068] The ionic liquid in step (1) is an organic molten salt formed by a cation and an anion, with a melting point below 100°C. For example, the cation of the ionic liquid is selected from at least one of the following: 1-ethyl-3-methylimidazolium cation, 1-propyl-3-methylimidazolium cation, 1-allyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, N-ethylpyridinium cation, N-butylpyridinium cation, N-n-hexylpyridinium cation; illustratively, the cation is selected from at least one of the following: 1-ethyl-3-methylimidazolium cation, 1-allyl-3-methylimidazolium cation, and 1-butyl-3-methylimidazolium cation. For example, the anion of the ionic liquid is selected from at least one of the following: chloride ion, bromide ion, formate ion, acetate ion, propionate ion, butyrate ion, and methyl phosphate ion; illustratively, the anion is selected from at least one of the following: chloride ion, formate ion, acetate ion, and methyl phosphate ion. Illustratively, the ionic liquid is 1-allyl-3-methylimidazolium chloride (AmimCl).

[0069] (2) Disperse the solution obtained in step (1) into an organic solvent, obtain microspheres by coaxial air flow shearing method, and obtain biomass-based hydrogel microspheres by regeneration with a precipitant and washing with deionized water.

[0070] The process condition parameters of the coaxial air flow shearing process in step (2) are not particularly limited and can be obtained using conventional coaxial air flow shearing equipment.

[0071] The precipitant in step (2) can be selected from at least one of water, alcohol, and ionic liquid aqueous solution. For example, the alcohol is selected from at least one of methanol, ethanol, propanol, isobutyl alcohol, and isopropyl alcohol, and the ionic liquid aqueous solution is preferably an aqueous solution of an ionic liquid type that dissolves cellulose, with a mass fraction of the ionic liquid preferably being 0-60%. Further, the process of regeneration in the precipitant can include the processes of coagulation, soaking, and washing of cellulose, for example, can be coagulated, soaked, and washed in different coagulation baths such as ionic liquid aqueous solution, water, alcohol, etc. Illustratively, the selected precipitant is a mixed solvent composed of ethanol and water (1:1).

[0072] (3) Perform solvent exchange on the biomass-based hydrogel microspheres in an organic solvent, add AIE fluorescent molecules and charged molecules, and perform reaction.

[0073] The charged molecules can be pre-activated. Illustratively, the N,N'-carbonyldiimidazole (CDI) activation treatment is performed.

[0074] The reaction in step (3) is an etherification reaction or an esterification reaction, the reaction temperature is 40-100°C, preferably 60°C, and the reaction time is 4-72h, preferably 8h.

[0075] (4) The product obtained in step (3) is sieved, purified, and solvent exchanged, or the product obtained in step (3) is tert-butanol exchanged and freeze-dried to obtain the biomass-based fluorescent material (also referred to as biomass-based charged fluorescent microspheres).

[0076] According to an exemplary embodiment of the present application, the method comprises the following steps:

[0077] 1) MCC is dispersed in AmimCl and heated and stirred until completely dissolved to obtain an MCC / AmimCl solution;

[0078] 2) DMF is added to the MCC / AmimCl solution, and after stirring and centrifugation, microspheres are obtained by coaxial airflow shearing method, and then regenerated in a poor solvent, washed with deionized water, and sieved with a screen to obtain MCC hydrogel microspheres of different sizes;

[0079] 3) The MCC hydrogel microspheres are immersed in DMSO, and after the solvent is completely replaced with DMSO, TPE-Br and an aqueous sodium hydroxide solution are added, and heated to react, and then washed with deionized water and DMSO to obtain MCC-TPE microspheres;

[0080] 4) N + -COOH and CDI are added to DMSO in steps, heated and stirred, and then added to the DMSO dispersion of the MCC-TPE microspheres obtained in step 2), heated to react, and then washed with DMSO and deionized water to obtain MCC-TPE-N + hydrogel microspheres;

[0081] 5) The solvent of the MCC-TPE-N + hydrogel microspheres is replaced with tert-butanol, and then freeze-dried to obtain MCC-TPE-N + aerogel microspheres.

[0082] Preferably, the following steps are included:

[0083] 1) MCC is dispersed in AmimCl and heated and stirred until completely dissolved to obtain an MCC / AmimCl solution;

[0084] 2) adding DMF to the MCC / AmimCl solution, stirring to obtain a homogeneous solution, and obtaining microspheres by coaxial airflow shearing after centrifugal deaeration, and then placing the microspheres in a poor solvent composed of ethanol and water (1:1) to regenerate, and then washing with deionized water and sieving with a screen to obtain MCC hydrogel microspheres of different sizes;

[0085] 3) immersing the MCC hydrogel microspheres in DMSO, replacing the solvent with DMSO for multiple times, adding TPE-Br and a sodium hydroxide aqueous solution, and reacting at 40-80°C (for example, 50-70°C, and exemplarily 60°C) for 2-12 hours (for example, 8 hours), and then washing with deionized water and DMSO, replacing the solvent with DMSO, and obtaining MCC-TPE microspheres;

[0086] 4) adding N + -COOH and CDI to DMSO in steps, stirring at a high speed at 60-100°C (for example, 70-90°C, and exemplarily 80°C) for 5-30 minutes (for example, 15 minutes), and then adding to a DMSO dispersion of the MCC-TPE microspheres obtained in step 2, and reacting at 40-80°C (for example, 50-70°C, and exemplarily 60°C) for 2-12 hours (for example, 8 hours), and then sieving the obtained microspheres, washing with DMSO and deionized water, and replacing the solvent with deionized water, to obtain MCC-TPE-N + hydrogel microspheres;

[0087] 5) replacing the solvent of the MCC-TPE-N + hydrogel microspheres with tert-butyl alcohol, and then freeze-drying, to obtain MCC-TPE-N + aerogel microspheres.

[0088] The biomass-based fluorescent material produces a fluorescence quenching effect on tobacco-specific nitrosamine compounds in the tobacco material, and the fluorescence quenching effect is used to identify the authenticity of the tobacco material.

[0089] The fluorescence quenching refers to a change in fluorescence after ultraviolet light irradiation, and the ultraviolet light is preferably 365 nm ultraviolet light.

[0090] The biomass-based fluorescent material produces a fluorescence quenching effect on tobacco-specific nitrosamine compounds in the tobacco material, and the fluorescence quenching effect is used to identify the authenticity of the tobacco material.

[0091] (1) grinding tobacco shreds in a tobacco product to be detected into powder, and immersing the powder in an ammonium acetate aqueous solution and oscillating to extract for a period of time (for example, 1 h);

[0092] (2) centrifuging the solution obtained in step (1) to obtain supernatant;

[0093] (3) The supernatant obtained in step (2) is filtered through a water-based filter membrane, and is made into an extraction liquid by constant volume;

[0094] (4) Biomass-based fluorescent material is added to the extraction liquid, and the fluorescence quenching effect of the biomass-based fluorescent material on tobacco-specific nitrosamines is used to identify the authenticity of the tobacco product.

[0095] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials and reagents used are commercially available unless otherwise specified. The equipment used in the experiments is well known to those skilled in the art unless otherwise specified.

[0096] Example 1

[0097] A preparation method of a cellulose-based fluorescent material, labeled as HPC-TPE, includes the following steps:

[0098] In a 100 mL two-necked flask, 1 g of HPC was weighed and added to 30 mL of DMSO, and was dissolved by stirring at 80°C. Then, 0.13 g of TPE-Br was added to the solution, and 0.24 g of sodium hydroxide was dissolved in 1 mL of deionized water, which was added dropwise to the above solution. The reaction was carried out at 80°C for 12 h. After the reaction was completed, the solution was placed in a dialysis bag (molecular weight cut-off 14000), and a mixed solution of deionized water and DMF (1:1) was used as the external liquid to dialyze and remove sodium hydroxide and unreacted small molecules. The external liquid was replaced multiple times until the pH was neutral and there was no fluorescence. Then, the external liquid was replaced with deionized water again, and the dialysis bag was replaced until the internal and external liquids were balanced. The liquid in the dialysis bag was concentrated and freeze-dried to obtain 0.85 g of a solid sample, i.e., HPC-TPE, with a yield of 85%. The degree of substitution of TPE in HPC-TPE was 0.054.

[0099] The synthesis route is as follows:

[0100]

[0101] Figure 1 (a) is the H NMR chart of HPC-TPE in Example 1. The benzene ring hydrogen nuclear magnetic peak signal at 6.5-7.0 ppm in the spectrum indicates that the halogenated fluorescent molecule has been bonded to the HPC chain. 1 Figure 1 (b) is the FTIR chart of HPC-TPE in Example 1. The characteristic stretching vibration peak of the aromatic ring at 1450-1600 cm -1 in the spectrum further proves that TPE has been bonded to the HPC chain.

[0102] ​HPC-TPE has significant aggregation-induced emission performance. After dissolved in good solvent DMF, the fluorescence of HPC-TPE is very weak. With the increase of the content of poor solvent water to completely dissolved in water, the fluorescence performance is greatly improved, and the fluorescence intensity is significantly enhanced. For HPC-TPE aqueous solution, with the increase of the concentration of aqueous solution, the fluorescence intensity first increases and then decreases, and the maximum emission wavelength gradually red shifts.

[0103] Example 2

[0104] A preparation method of cellulose microspheres, marked as MCC, comprises the following steps:

[0105] In a 250 mL two-necked flask, 2 g MCC was weighed and added into 30 g ionic liquid AmimCl, and a uniform transparent clear solution was obtained by stirring and dissolving at 80℃. 50 mL DMF was added, and a uniform solution was obtained by stirring. The microspheres were sprayed by a compressed air driven spraying device, the needle aperture and the air flow rate were adjusted to control the morphology of the microspheres, and a poor solvent regenerated cellulose solution composed of ethanol and water (1:1) was placed at the bottom of the spraying needle to obtain cellulose gel microspheres. The aforementioned microspheres were washed with deionized water for 3-4 times, and different sizes of MCC hydrogel microspheres were obtained by using a screen. After the solvent of the aforementioned MCC hydrogel microspheres was completely replaced by tert-butyl alcohol, freeze-drying was performed to obtain MCC aerogel microspheres.

[0106] The BET specific surface area of the MCC aerogel microspheres was 296.82 m 2 / g, and the average pore size was 14.13 nm.

[0107] Example 3

[0108] A preparation method of cellulose-based fluorescent microspheres, marked as MCC-TPE, comprises the following steps:

[0109] 30 mL MCC hydrogel microspheres prepared in Example 2 of the application were weighed, and DMSO was used to replace the soaking solvent multiple times. After the solvent was completely replaced by DMSO, the MCC hydrogel microspheres were placed in a 100 mL two-necked flask, 0.13 g TPE-Br was added at 60℃, and 0.24 g sodium hydroxide was dissolved in 1 mL deionized water, which was added dropwise into the above solution, and the reaction was carried out at 60℃ for 8 h. After the reaction, the microspheres were screened out by a screen, washed with deionized water multiple times to remove sodium hydroxide, washed with DMSO multiple times to remove unreacted small molecules, and replaced with DMSO multiple times to obtain MCC-TPE microspheres.

[0110] The synthetic route is as follows:

[0111]

[0112] The BET specific surface area of the MCC-TPE aerogel microspheres is 275.32 m 2 / g, and the average pore size is 16.67 nm.

[0113] The MCC-TPE microspheres have significant aggregation-induced emission performance. After being placed in a good solvent such as DMF or DMSO, the fluorescence of the MCC-TPE microspheres is very weak; in a poor solvent such as water, the fluorescence intensity is greatly enhanced.

[0114] Example 4

[0115] A preparation method of a cellulose-based positively charged fluorescent microsphere, labeled as MCC-TPE-N + , comprising the following steps:

[0116] In a 50 mL two-necked flask, 1.3452 g of N + -COOH and 1.2 g of CDI were added in two steps in 20 mL of DMSO at 80°C, and high-speed stirring was performed until no bubbles were generated in the solution in the flask, and the activation of N + -COOH was completed. 20 mL of the foregoing solution was added to the DMSO dispersion (30 mL) of the MCC-TPE microspheres prepared in Example 3 of the application, and the reaction was performed at 60°C for 8 h. After the reaction was completed, the obtained microspheres were sieved out with a sieve, washed with DMSO for multiple times to remove unreacted small molecules, and replaced with deionized water for multiple times to obtain MCC-TPE-N + hydrogel microspheres. After the solvent of the foregoing MCC-TPE-N + hydrogel microspheres was completely replaced with tert-butyl alcohol, freeze-drying was performed to obtain MCC-TPE-N + aerogel microspheres.

[0117] The synthetic route is shown as follows:

[0118]

[0119] The BET specific surface area of the MCC-TPE-N + microspheres is 257.36 m 2 / g, and the average pore size is 17.91 nm.

[0120] Figure 2 The FTIR spectrum of the cellulose-based microspheres MCC microspheres, cellulose-based fluorescent microspheres MCC-TPE microspheres, and cellulose-based positively charged fluorescent microspheres MCC-TPE-N + microspheres in Examples 2-4. As can be seen from the figure, compared with the MCC microspheres, in the FTIR spectrum of the synthesized MCC-TPE-N + microspheres, a carbonyl stretching vibration peak appears at 1734 cm -1 , and a peak appears at 1450-1600 cm-1 Weak aromatic ring characteristic stretching vibration peaks appeared, indicating that AIE fluorescent molecules TPE, charged molecules N + -COOH have been bonded on the MCC molecular chain.

[0121] The cellulose-based microspheres MCC microspheres, cellulose-based fluorescent microspheres MCC-TPE microspheres, cellulose-based positively charged fluorescent microspheres MCC-TPE-N + Elemental characterization results of the microspheres are listed in Table 1. MCC-TPE-N + The appearance of nitrogen element in the microspheres indicates the successful bonding of quaternary ammonium salt groups, and the change in the proportion of carbon element and nitrogen element in the MCC-TPE microspheres relative to the MCC microspheres indicates the successful bonding of fluorescent molecules.

[0122] Table 1: MCC, MCC-TPE, MCC-TPE-N + Elemental content percentage of the microspheres

[0123]

[0124] Figure 3 The scanning electron microscope photos of the MCC microspheres prepared in Example 2 of the present application and the MCC-TPE-N + microspheres prepared in Example 4. It can be seen that the unmodified cellulose microspheres have good sphericity and pore structure; after modification, the sphericity of the fluorescent microspheres is affected to a certain extent due to stirring and extrusion during the reaction, but the micro-pore structure has not changed relative to that before modification. Figure 3

[0125] MCC-TPE-N + The microspheres have significant aggregation-induced emission performance. After being placed in a good solvent such as DMF and DMSO, the MCC-TPE-N + microspheres have weak fluorescence; in a poor solvent such as water, the fluorescence intensity is greatly enhanced.

[0126] Example 5

[0127] HPC-TPE aqueous solution detects NNK:

[0128] Take 100 mg of HPC-TPE prepared in Example 1 of the present application and disperse it in 10 mL of deionized water to obtain an HPC-TPE aqueous solution (10 mg·mL -1 ). Add 1 ml of NNK of different concentrations (0-20 μM) to obtain different fluorescence responses.

[0129] Figure 4 The spectrum after adding NNK solution of different concentrations to the HPC-TPE aqueous solution in Example 5. It can be seen that Figure 4 ​(a) It can be seen from (a) that the HPC-TPE aqueous solution itself presents blue-green fluorescence, and the fluorescence of the solution is gradually quenched as the amount of NNK added is increased. Figure 4 (b) The Stern-Volmer in (b) is a curve that is curved upwards rather than a straight line, proving that the quenching efficiency of NNK on the fluorescence of the HPC-TPE aqueous solution is high, and has a signal amplification effect. The static quenching constant is calculated to be 2.85 x 10 4 L·moL -1 , and the detection limit is 0.11 μM. The fluorescence of the HPC-TPE aqueous solution cannot be recovered after being quenched.

[0130] The process for detecting the authenticity of tobacco products using the system is as follows:

[0131] (1) 1 g of a seized fake tobacco was ground into powder (after detection, the NNK content in the tobacco was 2.58 g / g), and was placed in a 125 ml conical flask, and then 100 ml of an ammonium acetate aqueous solution (concentration of 100 mM) was added and shaken for extraction for 1 h;

[0132] (2) The sample obtained in step (1) was centrifuged to obtain the supernatant;

[0133] (3) The supernatant was filtered using a 0.22 μm filter membrane, and was diluted to 100 ml, and the NNK concentration in the extraction solution was 0.125 .

[0134] (4) 1 ml of the extraction solution was added to the TPE-Br suspension, and since the concentration of NNK in the extraction solution reached the detection limit of the system, the fluorescence of the system was quenched, and it was determined that the tobacco product was fake.

[0135] Example 6

[0136] MCC-TPE-N + microspheres for detecting NNK:

[0137] 1 mL of an NNK aqueous solution with different concentrations (0-20 μM) was taken, and 10 mg of the MCC-TPE-N + microspheres prepared in Example 4 of the present application were added thereto, to obtain different fluorescence responses.

[0138] Figure 5 The spectral diagram of the MCC-TPE-N + microspheres after being immersed in an NNK aqueous solution with different concentrations is shown in (a). Figure 5 (a) It can be seen from (a) that the HPC-TPE aqueous solution itself presents blue-green fluorescence, and the fluorescence of the solution is gradually quenched as the amount of NNK added is increased. +The microspheres themselves present blue-green fluorescence. After being immersed in aqueous solutions of different concentrations of NNK, the fluorescence of the microspheres is gradually quenched with the increase of the concentration of NNK, and the fluorescence of the MCC-TPE-N + microspheres can be completely quenched at a relatively low concentration of NNK. Figure 5 The Stern-Volmer plot of (b) is a curve upwardly bent rather than a straight line, indicating that the quenching of the fluorescence of the MCC-TPE-N + microspheres by NNK is a dynamic process. 4 The quenching efficiency of the fluorescence of the microspheres is high, and the signal is amplified. The static quenching constant is calculated to be 1.06 x 10 -1 M + The detection limit is 0.035 μM.

[0139] Figure 6 In order to use the MCC-TPE-N + microspheres, the microspheres are immersed in an aqueous solution of NNK. -1 The fluorescence intensity of the microspheres is greatly reduced when the microspheres are immersed in an aqueous solution of NNK with a concentration of only 10 μg·mL + The solution is poured into a filter device, and the MCC-TPE-N + microspheres are filtered out and washed repeatedly with deionized water. The fluorescence spectrum of the suspension of the MCC-TPE-N + microspheres is recorded by a fluorescence spectrophotometer. After the cycle of immersion in the NNK solution and washing with deionized water, the fluorescence of the MCC-TPE-N + microspheres can be restored to the initial state, and the microspheres can still be used after being recycled for many times.

[0140] The process for detecting the authenticity of tobacco products by using the system is as follows:

[0141] (1) 1 g of a seized fake tobacco is ground into powder (the content of NNK in the tobacco is 1.27 g / g after detection), and is placed in a 125 ml conical flask, and then 100 ml of an aqueous ammonium acetate solution (with a concentration of 100 mM) is added to shake and extract for 1 h;

[0142] (2) The sample obtained in step (1) is centrifuged to obtain supernatant;

[0143] (3) The supernatant is filtered by using a 0.22 μm filter membrane, and is diluted to 100 ml. The concentration of NNK in the extraction solution is 0.0614 .

[0144] (4) 1 ml of the extraction solution is taken and added to 10 mg of the MCC-TPE-N +Microspheres, since the concentration of NNK in the extraction liquid reaches the detection limit of the system, the fluorescence of the system is quenched, and it can be determined that the tobacco product is fake tobacco.

[0145] Although some specific embodiments of the present application have been described in detail by way of example with reference to the accompanying drawings, it is to be understood that the examples are for illustrative purposes only and are not to be construed as limiting the scope of the present application. It is to be understood that modifications can be made to the above embodiments without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A biomass-based fluorescent material, characterized in that, The material comprises a matrix material and AIE fluorescent molecules bonded to the matrix material. The matrix material is selected from at least one of starch, chitosan, chitin, lignin, cellulose ester, cellulose ether, and microcrystalline cellulose. The AIE fluorescent molecules are selected from at least one of thiophene and its derivatives, styrene derivatives, pyrrole derivatives, fluorene and its derivatives, carbazole derivatives, thiophene compounds, and naphthalimide compounds. The degree of substitution of the AIE fluorescent molecules in the biomass-based fluorescent material is 0.0001-1.

0.

2. A method for preparing the biomass-based fluorescent material as described in claim 1, characterized in that, Includes the following steps: (1) Dissolve and disperse the matrix material in an organic solvent to obtain a homogeneous solution of the matrix material; (2) Disperse the AIE fluorescent molecules into a homogeneous solution of the matrix material and carry out the reaction; (3) The product obtained in step (2) is purified and dried to obtain biomass-based fluorescent material.

3. The preparation method according to claim 2, characterized in that, In step (2), the mass ratio of the matrix material to the AIE fluorescent molecules is 1:(0.01-5).

4. The preparation method according to claim 2, characterized in that, The reaction in step (2) is an etherification reaction, with a reaction temperature of 40-100℃ and a reaction time of 4-72h.

5. A biomass-based fluorescent material, characterized in that, The device comprises a matrix material, an AIE fluorescent molecule bonded to the matrix material, and a charged molecule bonded to the matrix material. The matrix material is selected from at least one of starch, chitosan, chitin, lignin, cellulose esters, cellulose ethers, and microcrystalline cellulose. The AIE fluorescent molecule is selected from at least one of thiophene and its derivatives, styrene derivatives, pyrrole derivatives, fluorene and its derivatives, carbazole derivatives, thiophene compounds, and naphthalimide compounds. The charged molecule is selected from at least one of quaternary ammonium salts, sulfonates, carboxylates, and betaine compounds.

6. A method for preparing the biomass-based fluorescent material as described in claim 5, characterized in that, Includes the following steps: (1) Dissolve and disperse the matrix material in the ionic liquid to obtain a homogeneous and transparent clear solution; (2) The solution obtained in step (1) is dispersed in an organic solvent and microspheres are obtained by coaxial airflow shearing. After regeneration with a precipitant and washing with deionized water, biomass-based hydrogel microspheres are obtained. (3) The biomass-based hydrogel microspheres were placed in an organic solvent for solvent exchange, and AIE fluorescent molecules and charged molecules were added to carry out the reaction; (4) The product obtained in step (3) is sieved, purified, and solvent-replaced, or the product obtained in step (3) is replaced with tert-butanol and freeze-dried to obtain biomass-based fluorescent materials.

7. The preparation method according to claim 6, characterized in that, The ionic liquid in step (1) is an organic molten salt with a melting point below 100°C, formed by cations and anions. The cation is selected from at least one of 1-ethyl-3-methylimidazolium cation, 1-propyl-3-methylimidazolium cation, 1-allyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, N-ethylpyridine cation, N-butylpyridine cation, and N-hexylpyridine cation. The anion is selected from at least one of chloride ion, bromide ion, formate ion, acetate ion, propionate ion, butyrate ion, and methyl phosphate ion.

8. The preparation method according to claim 6, characterized in that, The reaction in step (3) is an etherification reaction or an esterification reaction, with a reaction temperature of 40-100℃ and a reaction time of 4-72h.

9. The application of a biomass-based fluorescent material as described in claim 1 or 5, characterized in that, The authenticity of tobacco materials can be identified by observing the fluorescence changes of nitrosamine compounds in tobacco products produced by biomass-based fluorescent materials.

10. The application according to claim 9, characterized in that, Includes the following steps: (1) Grind the tobacco shreds in the tobacco product to be tested into powder, soak it in an ammonium acetate aqueous solution, and extract it by shaking for a period of time; (2) Centrifuge the solution obtained in step (1) to obtain the supernatant; (3) The supernatant obtained in step (2) is filtered through an aqueous filter membrane and the volume is adjusted to obtain the extract; (4) Add biomass-based fluorescent material to the extract and identify the authenticity of tobacco products by the fluorescence quenching effect of nitrosamine compounds on the biomass-based fluorescent material.

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