Preparation Of Photoresponsive Molecularly Imprinted Polymer And The Application In Environmental Analysis

Sulfa antibiotics(SAs),as a class of traditional antibacterial drugs,have been widely used since 1935,especially in the field of animal husbandry.However,due to its massive abuse,SAs residues have been detected in many animal-derived foods,natural water bodies and soils.When SAs exceeds the standard and enters the human body,it will cause the increase of drug-resistant bacteria in the body,affect the normal flora of the human body,and even cause health hazards such as kidney damage.Therefore,the detection of SAs in environmental samples and food is of great significance.Molecular imprinting technology(MIT)is a technology that uses molecularly imprinted polymers(MIPs)to simulate the interaction between enzyme-substrate or antibody-antigen to specifically identify target molecules.MIPs can be used as solid-phase extraction agents to specifically separate/enrich target substances.In recent years,stimulus-responsive MIPs that use external stimuli(conditions such as temperature,p H and light)to control adsorption and elution have become a research hotspot in the MIT field.In this paper,sulfamethazine(SMZ)was used as a template molecule,experimentally synthesized 4-[(4-methacryloyloxy)phenylazo]benzenesulfonic acid(MAPASA)and 5-[(4-(methacryloyloxy)phenyl)diazenyl]isophthalic acid(MAPDIA)as photosensitive monomer,PMMA,SiO₂ and Fe₃O₄ as carriers,using surface imprinting method to prepare three new types of MIPs.It was characterized by FT-IR,SEM,TEM,BET,TGA,UV-Vis,XRD,etc.The characteristics of adsorption,selectivity,and light response were studied.Finally,MIPs were successfully applied to the analysis and detection of SMZ in actual samples(milk,water samples).(1)Preparation and performance study of PMMA-based photoresponsive sulfamethazine imprinted polymer:Polymethyl methacrylate(PMMA)with a large number of ester groups on the surface is used as a carrier,SMZ is used as a template molecule,and MAPASA is used as a photoresponsive monomer and ethyl dimethacrylate(EGDMA)as cross-linking agent,six MIPs with different cross-linking agent and functional monomer ratio were prepared.After comparing the adsorption capacity,the optimal ratio is 1:4:20,which is recorded as PMMA@MIPs.PMMA@MIPs can specifically adsorb SMZ under dark or 440 nm irradiation,and release at 365 nm.Experiments show that the maximum adsorption capacity of PMMA@MIPs is 12.5 mg×g^-1,and the adsorption equilibrium is reached within 80 min.Good reusability,after 4 photocontrolled adsorption-release cycles,the performance is basically unchanged.It has good selectivity for SMZ(IF=3.01).Finally,PMMA@MIPs was successfully applied to the separation/enrichment of SMZ in milk,with a recovery rate of 97.5%.Shows that it can be used as a solid phase extraction agent in the separation process for the quantitative detection of SMZ in actual samples.(2)Preparation and performance study of photoresponsive sulfamethazine imprinted polymer based on SiO₂:using surface-modified SiO₂ as the carrier,MAPDIA as the photosensitive monomer,and EGDMA as the crosslinking agent,in three different solvents(DMF,DMSO,methanol),three MIPs were prepared.After comparing the adsorption capacity,DMF has the best effect,which is recorded as SiO₂@MIPs.Experiments show that the maximum adsorption capacity of SiO₂@MIPs is 28.82 mg×g^-1,and the adsorption equilibrium can be reached within 100 min.In addition,it has fast light response performance,and the trans-cis and cis-trans isomerization rate constants are 7.80×10^-3 s^-1 and 21.78×10^-3 s^-1,respectively.Finally,SiO₂@MIPs was successfully applied to the analysis and detection of SMZ in tap water,with a recovery rate of 89.8-96.7%.(3)Preparation of Fe₃O₄@SiO₂-based photoresponsive sulfamethazine imprinted polymer and its performance study:the silicon-coated and double bond modified magnetic Fe₃O₄ was used as the carrier,MAPDIA was used as the photosensitive monomer,EGDMA and N,N-methylenebisacrylamide(MBA)was used as a crosslinking agent to prepare magnetic photoresponsive MIPs.Compare the adsorption capacity of the two crosslinking agents in different proportions,and select the optimal group as Fe₃O₄@MIPs.Experiments show that the maximum adsorption capacity of Fe₃O₄@MIPs for SMZ is 25.06 mg×g^-1,the adsorption equilibrium is reached in 60 min,and the selectivity is good(IF=2.09).Finally,Fe₃O₄@MIPs was successfully applied to the analysis and detection of SMZ in river water,and the recovery rate was 88.5?95.7%.