Paper-based chip for detecting metal ions in environment by ion imprinting method and preparation method thereof

Abstract

The present application relates to the field of ion imprinting detection, discloses a paper-based chip for ion imprinting detection of metal ions in the environment and a preparation method thereof; the grafted quantum dots are prepared by the amidation reaction of chitosan and CdTe quantum dots, the occurrence of non-radiative recombination is reduced, the surface electrical environment is changed, the probability of non-radiative transition is reduced, so that the fluorescence emission intensity and quantum yield are improved, meanwhile, the high adhesion of chitosan can also effectively prevent the aggregation of quantum dots and improve the stability of quantum dots in aqueous solution. The chitosan is grafted with polydopamine and deposited on the surface of the glass fiber paper base together with polyethyleneimine, the copolymer of polydopamine and polyethyleneimine has strong adhesion and can build a firm polymer coating on the surface of the fiber; meanwhile, the polyethyleneimine can help to adsorb Cu 2+ , further improving the reliability of the paper-based chip in the detection process.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of ion imprinting method detection, in particular to a paper-based chip for detecting metal ions in the environment by ion imprinting method and a preparation method thereof. BACKGROUND

[0002] At present, in the fields of manufacturing, construction, medical treatment, etc., there are a large number of copper materials, which leads to overuse of copper materials. Meanwhile, improper treatment of waste copper materials leads to the copper materials becoming one of heavy metal pollutants, which pollutes water sources. When the copper materials enter the human body, they cause burden to organs such as liver, and cause metabolic disorder, resulting in diseases such as cirrhosis. Therefore, how to control and detect the content of Cu in water bodies has become a topic of increasing concern. 2+

[0003] Therefore, it is of great significance to invent a paper-based chip for detecting metal ions in the environment by ion imprinting method. SUMMARY

[0004] The present application aims to provide a paper-based chip for detecting metal ions in the environment by ion imprinting method and a preparation method thereof, so as to solve the problems in the background art.

[0005] In order to solve the above technical problems, the present application provides the following technical solutions:

[0006] The preparation method of the paper-based chip for detecting metal ions in the environment by ion imprinting method comprises the following steps:

[0007] S1: adding a CdTe quantum dot solution into a grafted chitosan solution, stirring and reacting to obtain a grafted quantum dot;

[0008] S2: adding the grafted quantum dot into a copper chloride solution, oscillating and reacting; adding polyethyleneimine and a buffer solution, adding glass fiber paper, oscillating and reacting under nitrogen condition to obtain a grafted glass paper substrate;

[0009] S3: adding the grafted glass paper substrate into an ethyl silicate solution, stirring and mixing, oscillating and reacting, and EDTA elution to obtain the paper-based chip.

[0010] Further, in the step S1, the grafted chitosan is prepared by the following method:

[0011] Chitosan and dopamine are dispersed in an acetic acid solution, the mixed solution is dropped into a sodium hydroxide solution, stirring and reacting, washing, and drying to obtain the grafted chitosan; wherein the mass ratio of chitosan to dopamine is 3:1.

[0012] ​Further, in the step S1, the CdTe quantum dot solution is a mixed solution of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride solution and CdTe quantum dot solution, wherein the concentration of the 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride solution is 0.2wt%, and the concentration of the CdTe quantum dot solution is 1.8×10 -6 mol / L; the solvent of the grafted chitosan solution is acetic acid solution with a concentration of 0.1mol / L, and the concentration of the grafted chitosan solution is 0.1wt%; the volume ratio of the 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride solution, the CdTe quantum dot solution and the grafted chitosan solution is 1:10:1.

[0013] Further, in the step S1, the reaction temperature is 20-25℃, and the pH during the reaction process is 7-9.

[0014] Further, in the step S2, the mass ratio of the grafted quantum dots to polyethyleneimine is (1-4):(1-2).

[0015] Further, in the step S2, the buffer solution is Tris-HCl buffer solution with a pH of 8.

[0016] Further, in the step S2, the copper chloride solution is a mixed solution of copper chloride and 3-aminopropyltrimethoxysilane; the mass ratio of ethyl silicate, copper chloride and 3-aminopropyltrimethoxysilane is 5:(0.17-0.2):1.

[0017] Further, the CdTe quantum dots are prepared by the following method:

[0018] The chromium chloride is dissolved in distilled water, the mercaptoacetic acid is added, the pH is adjusted to 9.0-9.2 by sodium hydroxide, and nitrogen is introduced for 20min to obtain the chromium chloride solution; the tellurium powder and sodium borohydride are added into 75% ethanol, and the reaction is carried out at 40℃ for 4h to obtain sodium telluride; the chromium chloride solution is added, and the reaction is carried out under the refluxing of nitrogen for 2h to obtain the CdTe quantum dots.

[0019] Compared with the prior art, the present application has the following beneficial effects: the grafted quantum dots are prepared by the amidation reaction of chitosan and CdTe quantum dots, the occurrence of the non-radiative recombination phenomenon caused by surface defects is reduced by the grafted quantum dots of chitosan, the surface electrical environment is changed, the probability of non-radiative transition is reduced, the fluorescence emission intensity and the quantum yield are improved, the Cu 2+ The fluorescence intensity in the detection process is improved, the fluorescence quenching effect is enhanced, and the ion detection sensitivity is improved; meanwhile, the high adhesion of chitosan can effectively prevent the agglomeration of quantum dots and improve the stability of quantum dots in water.

[0020] The present application grafts polydopamine on chitosan and co-deposits on the surface of glass fiber paper base with polyethylene imine, the copolymer of polydopamine and polyethylene imine has strong adhesion, and can construct a firm polymer coating on the fiber surface; meanwhile, polyethylene imine can help to adsorb Cu 2+ , and further improves the reliability of the paper-based chip in the detection process. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0022] In the following examples, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride is provided by Shenguo Bioengineering (Shanghai) Co., Ltd.; dopamine hydrochloride and chitosan (average molecular weight = 1500 Da) are provided by Sigma-Aldrich Chemical Company, USA; and polyethylene imine is provided by Shanghai Aladdin Reagent Co., Ltd.

[0023] Example 1

[0024] S1: 65 mg of chromium chloride was dissolved in 75 mL of distilled water, 60 μL of mercaptoacetic acid was added, and the pH was adjusted to 9.0 with sodium hydroxide. Nitrogen was introduced for 20 min to obtain a chromium chloride solution. 40 mg of tellurium powder and 40 mg of sodium borohydride were added to 2 mL of 75% ethanol, and the reaction was carried out at 40°C for 4 h to obtain sodium telluride. The chromium chloride solution was added, and the reaction was carried out under reflux for 2 h under a nitrogen atmosphere to obtain CdTe quantum dots;

[0025] S2: Chitosan and dopamine were dispersed in an acetic acid solution, and the mixed solution was dropped into a sodium hydroxide solution. After stirring and reaction, washing and drying were carried out to obtain grafted chitosan;

[0026] S3: 1 mL of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride solution and 1 mL of grafted chitosan solution were added to 10 mL of CdTe quantum dot solution, and the pH of the reaction system was maintained at 7. The reaction was carried out at 25°C for 2 h under stirring, and centrifugation was carried out at 6000 r / min for 15 min for filtration. The precipitate was washed with deionized water for 3 times to obtain grafted quantum dots;

[0027] S4: 0.2 g of copper chloride and 1 g of 3-aminopropyltrimethoxysilane were added into 5 mL of ethanol and mixed uniformly to obtain a copper chloride solution; 2 g of the grafted quantum dots were added into the copper chloride solution and oscillated at 25 °C for 4 h; the reaction product and 2 g of polyethyleneimine were added into a Tris-HCl buffer solution with a pH of 8, and glass fiber paper was added, and oscillated at 25 °C for 6 h under a nitrogen atmosphere, and eluted with EDTA to obtain the grafted glass paper substrate;

[0028] S5: 5 g of ethyl silicate was added into 5 mL of water and mixed uniformly, and hydrochloric acid was added to adjust the pH to 2 to obtain an ethyl silicate solution; the grafted glass paper substrate was added into the ethyl silicate solution and stirred and mixed, and oscillated at 25 °C for 4 h to obtain the paper-based chip.

[0029] Test: adsorption performance test

[0030] Blank sample preparation: the grafted glass paper substrate was prepared according to the above steps S1-S4, 5 g of ethyl silicate was added into 5 mL of water and mixed uniformly, and hydrochloric acid was added to adjust the pH to 2 to obtain an ethyl silicate solution; 1 g of 3-aminopropyltrimethoxysilane was added into 5 mL of ethanol and mixed uniformly to obtain a 3-aminopropyltrimethoxysilane solution; the ethyl silicate solution and the 3-aminopropyltrimethoxysilane solution were stirred and mixed, and the grafted glass paper substrate was added, and oscillated at 25 °C for 4 h to obtain the paper-based chip.

[0031] The paper-based chip prepared in the blank sample was soaked in 10 mL of Cu 2+ solutions with different concentrations and pH = 7, and the concentrations were 0.96 mg / L, respectively. The paper was incubated by oscillation at room temperature, and the paper was taken out after 15 min, and the fluorescence intensity F0 was detected by a fluorescence spectrometer;

[0032] The paper-based chip prepared in Example 1 was soaked in 10 mL of Cu 2+ solutions with different concentrations and pH = 7, and the concentrations were 0.96 mg / L, respectively. The paper was incubated by oscillation at room temperature, and the paper was taken out after 15 min, and the fluorescence intensity F was detected by a fluorescence spectrometer.

[0033] Example 2

[0034] S1: 65 mg of chromium chloride was dissolved in 75 mL of distilled water, 60 μL of mercaptoacetic acid was added, and the pH was adjusted to 9.0 with sodium hydroxide, and nitrogen was introduced for 20 min to obtain a chromium chloride solution; 40 mg of tellurium powder and 40 mg of sodium borohydride were added into 2 mL of 75% ethanol and reacted at 40 °C for 4 h to obtain sodium telluride; the chromium chloride solution was added, and the reaction was carried out under reflux for 2 h under a nitrogen atmosphere to obtain CdTe quantum dots;

[0035] S2: dispersing chitosan and dopamine in acetic acid solution, dropping the mixed solution into sodium hydroxide solution, stirring and reacting, washing, and drying to obtain grafted chitosan;

[0036] S3: adding 1 mL of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride solution and 1 mL of grafted chitosan solution into 10 mL of CdTe quantum dot solution, maintaining the pH of the reaction system at 7.5, stirring and reacting at 25℃ for 2 h, centrifuging at 6000 r / min for 15 min, filtering, and washing the precipitate with deionized water for 3 times to obtain grafted quantum dots;

[0037] S4: adding 0.2 g of copper chloride and 1 g of 3-aminopropyltrimethoxysilane into 5 mL of ethanol, mixing uniformly to obtain a copper chloride solution; adding 2 g of grafted quantum dots into the copper chloride solution, oscillating and reacting at 25℃ for 4 h; adding the reaction product and 2 g of polyethyleneimine into a Tris-HCl buffer solution with a pH of 8, adding glass fiber paper, oscillating and reacting at 25℃ for 6 h under nitrogen, and eluting with EDTA to obtain a grafted glass paper substrate;

[0038] S5: adding 5 g of ethyl silicate into 5 mL of water, mixing uniformly, adding hydrochloric acid to adjust the pH to 2 to obtain an ethyl silicate solution; adding the grafted glass paper substrate into the ethyl silicate solution, stirring and mixing, and oscillating and reacting at 25℃ for 4 h to obtain a paper chip.

[0039] Test: adsorption performance test

[0040] Blank sample preparation: the grafted glass paper substrate was prepared according to the above steps S1-S4, 5 g of ethyl silicate was added into 5 mL of water, mixed uniformly, hydrochloric acid was added to adjust the pH to 2 to obtain an ethyl silicate solution; 1 g of 3-aminopropyltrimethoxysilane was added into 5 mL of ethanol, mixed uniformly to obtain a 3-aminopropyltrimethoxysilane solution; the ethyl silicate solution and the 3-aminopropyltrimethoxysilane solution were stirred and mixed, the grafted glass paper substrate was added, and oscillating and reacting at 25℃ for 4 h to obtain a paper chip.

[0041] The paper chip prepared by the blank sample was soaked in 10 mL of Cu 2+ solution with different concentrations and pH=7, and the concentrations were 0.96 mg / L respectively. The paper sheet was oscillated and cultivated at room temperature, and the paper sheet was taken out after 15 min, and the fluorescence intensity F0 was detected by a fluorescence spectrometer;

[0042] The paper chip prepared in Example 2 was soaked in 10 mL of Cu 2+ solution with different concentrations and pH=7, and the concentrations were 0.96 mg / L respectively. The paper sheet was oscillated and cultivated at room temperature, and the paper sheet was taken out after 15 min, and the fluorescence intensity F was detected by a fluorescence spectrometer.

[0043] Example 3

[0044] S1: 65 mg of chromium chloride was dissolved in 75 mL of distilled water, 60 μL of mercaptoacetic acid was added, and the pH was adjusted to 9.0 with sodium hydroxide, and nitrogen was bubbled for 20 min to obtain a chromium chloride solution; 40 mg of tellurium powder and 40 mg of sodium borohydride were added to 2 mL of 75% ethanol, and reacted at 40°C for 4 h to obtain sodium telluride; the chromium chloride solution was added, and the reaction was carried out under reflux for 2 h under a nitrogen atmosphere to obtain CdTe quantum dots;

[0045] S2: Chitosan and dopamine were dispersed in an acetic acid solution, and the mixed solution was added dropwise to a sodium hydroxide solution, and the reaction was carried out with stirring, and the product was washed and dried to obtain grafted chitosan;

[0046] S3: 1 mL of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride solution and 1 mL of grafted chitosan solution were added to 10 mL of CdTe quantum dot solution, the pH of the reaction system was maintained at 8, and the reaction was carried out at 25°C with stirring for 2 h, and the product was filtered by centrifugation at 6000 r / min for 15 min, and the precipitate was washed with deionized water 3 times to obtain grafted quantum dots;

[0047] S4: 0.2 g of copper chloride and 1 g of 3-aminopropyltrimethoxysilane were added to 5 mL of ethanol and mixed uniformly to obtain a copper chloride solution; 2 g of grafted quantum dots were added to the copper chloride solution, and the reaction was carried out at 25°C with oscillation for 4 h; the reaction product and 2 g of polyethyleneimine were added to a Tris-HCl buffer solution with a pH of 8, and glass fiber paper was added, and the reaction was carried out at 25°C with oscillation for 6 h under a nitrogen atmosphere, and EDTA was used for elution to obtain a grafted glass paper substrate;

[0048] S5: 5 g of ethyl silicate was added to 5 mL of water and mixed uniformly, and hydrochloric acid was added to adjust the pH to 2 to obtain an ethyl silicate solution; the grafted glass paper substrate was added to the ethyl silicate solution and mixed with stirring, and the reaction was carried out at 25°C with oscillation for 4 h to obtain a paper-based chip.

[0049] Test: Adsorption performance test

[0050] Blank sample preparation: The grafted glass paper substrate was prepared according to the above steps S1-S4, 5 g of ethyl silicate was added to 5 mL of water and mixed uniformly, and hydrochloric acid was added to adjust the pH to 2 to obtain an ethyl silicate solution; 1 g of 3-aminopropyltrimethoxysilane was added to 5 mL of ethanol and mixed uniformly to obtain a 3-aminopropyltrimethoxysilane solution; the ethyl silicate solution and the 3-aminopropyltrimethoxysilane solution were mixed with stirring, and the grafted glass paper substrate was added, and the reaction was carried out at 25°C with oscillation for 4 h to obtain a paper-based chip.

[0051] The paper-based chip prepared in the blank sample was immersed in 10 mL of Cu 2+The concentration in the solution was 0.96 mg / L respectively. The paper sheet was incubated under the condition of room temperature, and the paper sheet was taken out after 15 min. The fluorescence intensity F0 was detected by the fluorescence spectrometer.

[0052] The paper-based chip prepared in Example 3 was soaked in 10 mL of Cu 2+ The concentration in the solution was 0.96 mg / L respectively. The paper sheet was incubated under the condition of room temperature, and the paper sheet was taken out after 15 min. The fluorescence intensity F0 was detected by the fluorescence spectrometer.

[0053] Example 4

[0054] S1: 65 mg of chromium chloride was dissolved in 75 mL of distilled water, 60 μL of mercaptoacetic acid was added, and the pH was adjusted to 9.0 with sodium hydroxide. Nitrogen was introduced for 20 min to obtain a chromium chloride solution. 40 mg of tellurium powder and 40 mg of sodium borohydride were added to 2 mL of 75% ethanol, and the mixture was reacted at 40°C for 4 h to obtain sodium telluride. The chromium chloride solution was added, and the reaction was carried out under reflux for 2 h to obtain CdTe quantum dots;

[0055] S2: Chitosan and dopamine were dispersed in an acetic acid solution, and the mixed solution was dropped into a sodium hydroxide solution. The mixture was stirred and reacted, washed, and dried to obtain grafted chitosan;

[0056] S3: 1 mL of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride solution and 1 mL of grafted chitosan solution were added to 10 mL of CdTe quantum dot solution. The pH of the reaction system was maintained at 8.5, and the mixture was stirred at 25°C for 2 h. The mixture was centrifuged at 6000 r / min for 15 min, filtered, and the precipitate was washed with deionized water for 3 times to obtain grafted quantum dots;

[0057] S4: 0.2 g of copper chloride and 1 g of 3-aminopropyltrimethoxysilane were added to 5 mL of ethanol, and the mixture was mixed uniformly to obtain a copper chloride solution. 2 g of grafted quantum dots were added to the copper chloride solution, and the mixture was stirred at 25°C for 4 h. The reaction product and 2 g of polyethyleneimine were added to a Tris-HCl buffer solution with a pH of 8, and glass fiber paper was added. The mixture was stirred at 25°C for 6 h under a nitrogen atmosphere, and EDTA was used for elution to obtain a grafted glass paper substrate.

[0058] S5: 5 g of ethyl silicate was added to 5 mL of water, and the pH was adjusted to 2 with hydrochloric acid to obtain an ethyl silicate solution. The grafted glass paper substrate was added to the ethyl silicate solution, and the mixture was stirred and mixed. The mixture was stirred at 25°C for 4 h to obtain a paper-based chip.

[0059] Test: adsorption performance test

[0060] Blank sample preparation: the grafted glass paper substrate was prepared according to the above steps S1-S4, 5g ethyl silicate was added into 5mL water and mixed uniformly, hydrochloric acid was added to adjust the pH to 2 to obtain an ethyl silicate solution; 1g 3-aminopropyl trimethoxysilane was added into 5mL ethanol and mixed uniformly to obtain a 3-aminopropyl trimethoxysilane solution; the ethyl silicate solution and the 3-aminopropyl trimethoxysilane solution were stirred and mixed, and the grafted glass paper substrate was added, and the reaction was carried out at 25°C for 4h to obtain a paper-based chip.

[0061] The paper-based chip prepared in the blank sample was soaked in 10mL of Cu 2+ solution with different concentrations at pH=7, and the concentrations were 0.96mg / L respectively. The paper sheet was incubated under room temperature condition, and the paper sheet was taken out after 15min, and the fluorescence intensity F0 was detected by a fluorescence spectrometer;

[0062] The paper-based chip prepared in Example 4 was soaked in 10mL of Cu 2+ solution with different concentrations at pH=7, and the concentrations were 0.96mg / L respectively. The paper sheet was incubated under room temperature condition, and the paper sheet was taken out after 15min, and the fluorescence intensity F was detected by a fluorescence spectrometer.

[0063] Example 5

[0064] S1: 65mg of chromium chloride was dissolved in 75mL of distilled water, 60μL of mercaptoacetic acid was added, and the pH was adjusted to 9.0 with sodium hydroxide, and nitrogen was introduced for 20min to obtain a chromium chloride solution; 40mg of tellurium powder and 40mg of sodium borohydride were added into 2mL of 75% ethanol, and the reaction was carried out at 40°C for 4h to obtain sodium telluride; the chromium chloride solution was added, and the reaction was carried out under reflux for 2h to obtain CdTe quantum dots;

[0065] S2: chitosan and dopamine were dispersed in acetic acid solution, and the mixed solution was dropped into sodium hydroxide solution, and the reaction was carried out under stirring, washing and drying to obtain grafted chitosan;

[0066] S3: 1mL of 1-ethyl-(3-dimethylaminopropyl) carbonyl diimide hydrochloride solution and 1mL of grafted chitosan solution were added into 10mL of CdTe quantum dot solution, the pH of the reaction system was maintained at 9, and the reaction was carried out under stirring at 25°C for 2h, and the reaction system was centrifuged at 6000r / min for 15min, and the precipitate was washed with deionized water for 3 times to obtain grafted quantum dots;

[0067] S4: 0.2 g of copper chloride and 1 g of 3-aminopropyltrimethoxysilane were added into 5 mL of ethanol and mixed uniformly to obtain a copper chloride solution; 2 g of the grafted quantum dots were added into the copper chloride solution and oscillated at 25 °C for 4 h; the reaction product and 2 g of polyethyleneimine were added into a Tris-HCl buffer solution with a pH of 8, and glass fiber paper was added, and oscillated at 25 °C for 6 h under a nitrogen atmosphere, and eluted with EDTA to obtain the grafted glass paper substrate;

[0068] S5: 5 g of ethyl silicate was added into 5 mL of water and mixed uniformly, and hydrochloric acid was added to adjust the pH to 2 to obtain an ethyl silicate solution; the grafted glass paper substrate was added into the ethyl silicate solution and stirred and mixed, and oscillated at 25 °C for 4 h to obtain the paper-based chip.

[0069] Test: adsorption performance test

[0070] Preparation of a blank sample: the grafted glass paper substrate was prepared according to the above steps S1-S4, 5 g of ethyl silicate was added into 5 mL of water and mixed uniformly, and hydrochloric acid was added to adjust the pH to 2 to obtain an ethyl silicate solution; 1 g of 3-aminopropyltrimethoxysilane was added into 5 mL of ethanol and mixed uniformly to obtain a 3-aminopropyltrimethoxysilane solution; the ethyl silicate solution and the 3-aminopropyltrimethoxysilane solution were stirred and mixed, and the grafted glass paper substrate was added, and oscillated at 25 °C for 4 h to obtain the paper-based chip.

[0071] The paper-based chip prepared in the blank sample was soaked in 10 mL of Cu 2+ solutions with different concentrations and pH = 7, and the concentrations were 0.96 mg / L, respectively. The paper sheet was oscillated and cultivated at room temperature, and the paper sheet was taken out after 15 min, and the fluorescence intensity F0 was detected by a fluorescence spectrometer;

[0072] The paper-based chip prepared in Example 5 was soaked in 10 mL of Cu 2+ solutions with different concentrations and pH = 7, and the concentrations were 0.96 mg / L, respectively. The paper sheet was oscillated and cultivated at room temperature, and the paper sheet was taken out after 15 min, and the fluorescence intensity F was detected by a fluorescence spectrometer.

[0073] Comparative Example 1

[0074] S1: 65 mg of chromium chloride was dissolved in 75 mL of distilled water, 60 μL of mercaptoacetic acid was added, and the pH was adjusted to 9.0 with sodium hydroxide, and nitrogen was introduced for 20 min to obtain a chromium chloride solution; 40 mg of tellurium powder and 40 mg of sodium borohydride were added into 2 mL of 75% ethanol and reacted at 40 °C for 4 h to obtain sodium telluride; the chromium chloride solution was added, and the reaction was carried out under reflux for 2 h under a nitrogen atmosphere to obtain CdTe quantum dots;

[0075] S2: dispersing chitosan and dopamine in acetic acid solution, dropping the mixed solution into sodium hydroxide solution, stirring and reacting, washing, and drying to obtain grafted chitosan;

[0076] S3: adding 1 mL of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride solution and 1 mL of grafted chitosan solution into 10 mL of CdTe quantum dot solution, maintaining the pH of the reaction system at 5, stirring and reacting at 25℃ for 2 h, centrifuging at 6000 r / min for 15 min for filtration, and washing the precipitate with deionized water for 3 times to obtain grafted quantum dots;

[0077] S4: adding 0.2 g of copper chloride and 1 g of 3-aminopropyltrimethoxysilane into 5 mL of ethanol to uniformly mix to obtain a copper chloride solution; adding 2 g of grafted quantum dots into the copper chloride solution, and oscillating and reacting at 25℃ for 4 h; adding the reaction product and 2 g of polyethyleneimine into a Tris-HCl buffer solution with a pH of 8, adding glass fiber paper, oscillating and reacting at 25℃ for 6 h under nitrogen, and eluting with EDTA to obtain a grafted glass paper substrate;

[0078] S5: uniformly mixing 5 g of ethyl silicate into 5 mL of water, adding hydrochloric acid to adjust the pH to 2 to obtain an ethyl silicate solution; adding the grafted glass paper substrate into the ethyl silicate solution to stir and mix, and oscillating and reacting at 25℃ for 4 h to obtain a paper chip.

[0079] Test: adsorption performance test

[0080] Blank sample preparation: the grafted glass paper substrate is prepared according to the above steps S1-S4, 5 g of ethyl silicate is uniformly mixed into 5 mL of water, hydrochloric acid is added to adjust the pH to 2 to obtain an ethyl silicate solution; 1 g of 3-aminopropyltrimethoxysilane is added into 5 mL of ethanol to uniformly mix to obtain a 3-aminopropyltrimethoxysilane solution; the ethyl silicate solution and the 3-aminopropyltrimethoxysilane solution are stirred and mixed, the grafted glass paper substrate is added, and oscillating and reacting at 25℃ for 4 h to obtain a paper chip.

[0081] The paper chip prepared by the blank sample is soaked in 10 mL of Cu 2+ solutions with different concentrations and pH=7, and the concentrations are 0.96 mg / L respectively. The paper sheet is incubated by oscillation at room temperature, and the paper sheet is taken out after 15 min, and the fluorescence intensity F0 is detected by a fluorescence spectrometer.

[0082] The paper chip prepared by the blank sample is soaked in 10 mL of Cu 2+ solutions with different concentrations and pH=7, and the concentrations are 0.96 mg / L respectively. The paper sheet is incubated by oscillation at room temperature, and the paper sheet is taken out after 15 min, and the fluorescence intensity F is detected by a fluorescence spectrometer.

[0083] Comparative Example 2

[0084] S1: 65 mg of chromium chloride was dissolved in 75 mL of distilled water, 60 μL of mercaptoacetic acid was added, and the pH was adjusted to 9.0 with sodium hydroxide, and nitrogen was bubbled for 20 min to obtain a chromium chloride solution; 40 mg of tellurium powder and 40 mg of sodium borohydride were added to 2 mL of 75% ethanol, and reacted at 40°C for 4 h to obtain sodium telluride; the chromium chloride solution was added, and the reaction was carried out under reflux for 2 h under a nitrogen atmosphere to obtain CdTe quantum dots;

[0085] S2: the glass fiber paper was immersed in 0.2 mol / L hydrochloric acid solution for 30 min, taken out and placed in 20 mL of 50% ethanol solution, 200 μL of APTES was added, and the reaction was carried out for 2 h to obtain glass fiber paper A; 5 mL of 20 mg / mL EDTC and 5 mL of 10 mg / mL NHS were added to the CdTe quantum dot solution, the pH was adjusted to 5, glass fiber paper A was added, and the paper was incubated in the dark for 12 h to obtain a grafted glass paper substrate;

[0086] S3: 5 g of ethyl silicate was added to 5 mL of water, mixed uniformly, and hydrochloric acid was added to adjust the pH to 2 to obtain an ethyl silicate solution; 0.2 g of copper chloride and 1 g of 3-aminopropyltrimethoxysilane were added to 5 mL of ethanol, mixed uniformly, and a copper chloride solution was obtained; the ethyl silicate solution and the copper chloride solution were stirred and mixed, and the grafted glass paper substrate was added, and the reaction was carried out at 25°C for 4 h to obtain a paper-based chip.

[0087] Test: adsorption performance test

[0088] Blank sample preparation: the grafted glass paper substrate was prepared according to the above steps S1-S2, 5 g of ethyl silicate was added to 5 mL of water, mixed uniformly, and hydrochloric acid was added to adjust the pH to 2 to obtain an ethyl silicate solution; 1 g of 3-aminopropyltrimethoxysilane was added to 5 mL of ethanol, mixed uniformly, and a 3-aminopropyltrimethoxysilane solution was obtained; the ethyl silicate solution and the 3-aminopropyltrimethoxysilane solution were stirred and mixed, and the grafted glass paper substrate was added, and the reaction was carried out at 25°C for 4 h to obtain a paper-based chip.

[0089] The paper-based chip prepared by the blank sample was immersed in 10 mL of Cu 2+ solution with different concentrations at pH = 7, and the concentrations were 0.96 mg / L, respectively. The paper sheet was incubated under oscillation at room temperature, and the paper sheet was taken out after 15 min, and the fluorescence intensity F0 was detected by a fluorescence spectrometer;

[0090] The paper-based chip prepared by the blank sample was immersed in 10 mL of Cu 2+ solution with different concentrations at pH = 7, and the concentrations were 0.96 mg / L, respectively. The paper sheet was incubated under oscillation at room temperature, and the paper sheet was taken out after 15 min, and the fluorescence intensity F was detected by a fluorescence spectrometer;

[0091] The test data are shown in the following table:

[0092] fluorescence intensity F0 / F Example 1 1.43 Example 2 1.56 Example 3 1.63 Example 4 1.69 Example 5 1.74 Comparative Example 1 1.21 Comparative Example 2 1.38

[0093] Conclusion: From Examples 1-5, it can be seen that when the pH of the reaction system is 9 during the preparation of the grafted quantum dots, the paper-based chip prepared has the best performance; in Comparative Example 1, the pH of the reaction system is too low during the preparation of the grafted quantum dots, which leads to the collapse of chitosan grafting and low grafting rate, resulting in the decrease of the performance of the paper-based chip prepared; in Comparative Example 2, chitosan is not used to graft CdTe quantum dots during the preparation of the grafted quantum dots, and the fluorescence intensity of the quantum dots is low during the detection, leading to the decrease of the performance of the paper-based chip prepared.

[0094] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or make equivalent replacements to some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a paper-based chip for detecting copper ions in the environment by ion imprinting, characterized in that: The method comprises the following steps: S1: adding a mixed solution of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and CdTe quantum dot solution into a grafted chitosan solution, stirring and reacting to obtain grafted quantum dots; S2: adding the grafted quantum dots into a mixed solution of copper chloride and 3-aminopropyltrimethoxysilane, oscillating and reacting; adding polyethyleneimine and a buffer solution, adding glass fiber paper, oscillating and reacting under nitrogen condition to obtain a grafted glass paper substrate; S3: adding the grafted glass paper substrate into an ethyl silicate solution, stirring and mixing, oscillating and reacting, and EDTA elution to obtain a paper-based chip; The grafted chitosan is prepared by the following method: dispersing chitosan and dopamine in an acetic acid solution, dropping the mixed solution into a sodium hydroxide solution, stirring and reacting, washing, and drying to obtain the grafted chitosan; wherein the mass ratio of chitosan to dopamine is 3:1; The concentration of the 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride solution is 0.2wt%, the concentration of the CdTe quantum dot solution is 1.8×10 -6 mol / L; the solvent of the grafted chitosan solution is acetic acid solution with a concentration of 0.1mol / L, the concentration of the grafted chitosan solution is 0.1wt%; the volume ratio of the 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride solution, the CdTe quantum dot solution and the grafted chitosan solution is 1:10:

1. The mass ratio of ethyl silicate to copper chloride to 3-aminopropyltrimethoxysilane is 5:(0.17-0.2):

1.

2. The method for preparing a paper-based chip for detecting copper ions in the environment by ion imprinting according to claim 1, characterized in that: In step S1, the reaction temperature is 20-25℃, and the pH during the reaction process is 7-9.

3. The method for preparing a paper-based chip for ion imprinting detection of copper ions in the environment according to claim 1, characterized in that: In step S2, the mass ratio of grafted quantum dots to polyethyleneimine is (1-4):(1-2).

4. The method for preparing a paper-based chip for ion imprinting detection of copper ions in the environment according to claim 1, characterized in that: In step S2, the buffer solution is a Tris-HCl buffer solution with a pH of 8.

5. The paper-based chip prepared by the preparation method of the ion imprinting method for detecting copper ions in the environment according to any one of claims 1-4.