Preparation Of Molecularly Imprinted Polymers And Carbon Dots And Their Detection Of Antibiotics

Antibiotics are widely used in agriculture,aquaculture and animal husbandry.Antibiotic misuse is now widespread.Excessive amounts of antibiotics are frequently detected in environmental samples such as water bodies and soil.In response to this situation,many countries have formulated corresponding policies to limit the abuse of antibiotics,but the current situation is still not optimistic.Excessive antibiotics will enter the human body through the food chain,causing skin allergies,tuberculosis,liver disease and other complications,but also make the human body antibiotic-resistant genes,serious harm to human health.Therefore,it is important for human health to develop practical,simple and sensitive antibiotic detection methods.In this paper,a molecular imprinted polymer and two fluorescent carbon dots have been prepared and used for the detection of tetracycline and gentamycin,respectively.The main research contents are as follows:Using tetracycline as template and silica gel as carrier,a surface molecularly imprinted polymer with tetracycline selectivity was synthesized by free radical polymerization.The surface morphology and chemical composition of the polymer were characterized by Scanning electron microscopy and Fourier infrared spectrometer.The adsorption of tetracycline by imprinted polymers and non-imprinted polymers can reach equilibrium in about 1.5 h,and the maximum tetracycline adsorption capacity of them were 26.38 and 22.02 mg/g,respectively,and the calculated imprinting factor was 1.2.Langmuir and Freundlich fitting results showed that the adsorption of tetracycline by imprinted polymers and non-imprinted polymers belonged to monolayer adsorption.Nitrogen,sulfur co-doped fluorescent carbon dots(N,S-CDs)were synthesized using congo red as precursor.N,S-CDs have good water solubility and optical stability,and the quantum yield is 32%.The optimal excitation wavelength and emission wavelength of N,S-CDs are 370 nm and 447 nm,respectively.Gentamicin can quench the fluorescence of N,S-CDs by static quenching.Therefore,an analytical method was established for gentamicin detection.The linear range of the method is 10～500 n M and the detection limit is 1.8 n M.Finally,the method was applied to the detection of gentamicin in milk.The recoveries were between 99.30～101.53%,and relative standard deviation were all less than 5%.Blue-emitting carbon dots(B-CDs)was synthesized with ammonium citrate and o-phlorine as precursors.The optimal excitation and emission wavelengths for B-CDs are350 and 450 nm,respectively.An analytical method for tetracycline detection was established based on internal filter effect.The fluorescence of B-CDs can be linearly quenched by tetracycline in the concentration range of 0.5～50 μM,and the detection limit is 0.13 μM.This method was used for the spike detection of tetracycline in distilled water and tap wabter,and the recovery rate was in 99.42 to 104.24%.This analysis method is proved to have good accuracy.In addition,internal filter effect has been extended.Yellow fluorescent carbon dots(Y-CDs)was synthesized with p-phenylenediamine,methacrylic acid and triethylamine as precursors.An analytical method for the determination of tartrazine was established based on internal filter effect.The linear range of the method is0.05～3 μM,and the detection limit is 0.018 μM.Finally,the method was used for the determination of tartrazine in drinks and cells.