Construction Of Electrochemical Sensor Based On Surface Molecular Imprinting Polymer And Its Application In Detection Of Antibiotic

Antibiotics are widely used in medicine due to their excellent bacteriostatic effect.However,the absorption of antibiotics by animals is limited,and most antibiotics enter the environment through animal feces and urine.With the spread of the biological chain,antibiotic residues accumulate in various organisms,eventually causing serious harm to the human body.Human exposure to antibiotics long-term can lead to bacterial resistance,and the emergence of"super-resistant bacteria" will further threaten human health.Therefore,the effective detection of antibiotic residues has far-reaching significance.Molecularly imprinted polymers(MIPs)can provide specific recognition and selective adsorption for target molecules.MIPs have many commercial prospects and high practical application value in the field of sensor analysis due to their simple preparation,low cost and high chemical stability.Compared with other types of sensors,electrochemical sensors have the unique advantages of high sensitivity,fast analysis speed,simple equipment operation and portability.The modification of the electrode by nanomaterials can not only to amplify the signal through catalytic activity and conductivity,but also to enrich the recognition sites through its large specific surface area.Therefore,based on the advantages of molecularly imprinted polymers,electrochemical sensors and nanomaterials,a series of electrochemical sensors for sensitive detection of antibiotics were prepared.The specific research contents are as follows:(1)A novel molecularly imprinted electrochemical sensor(MIP/MC@Au/GCE)for the detection of trace sulfadiazine(SDZ)based on electropolymerized pyrrole(Py)molecularly imprinted polymers(MIPs)was developed.Gold nanoparticles(Au NPs)modified porous material MC@Au was obtained by introducing gold precursor into polymetallic doped MOFs(CoNiFeMOF)and heat treatment under inert gas protection.MC@Au improves the electron transfer ability and specific surface area of the electrod,increases the active recognition site and conductivity.Based on the modified materials,MIPs were prepared by electropolymerization with Py as functional monomer and SDZ as template molecule.Under the optimal conditions,the differential pulse voltammetry(DPV)detection has a good linear ranges:8×10-7 mol/L to 6.8×10-6 mol/L and 6.8×10-6 mol/L to 1.8×10-4 mol/L.(2)An electrochemical sensor for determining TC based on surface molecular imprinted polymer(SMIP)was constucted.The mesoporous magnetic nanomaterials(Fe3O4@SiO2@mTiO2)possessing higher specific surface area were successfully fabricated and used as the imprinted support after being modified by dopamine functionalized reversible addition-fragmentation chain transfer(RAFT)agent.The magnetic molecular imprinted polymer(MSMIP)was finally prepared through a surface-initiated reversible additionfragmentation chain transfer(SI-RAFT)polymerization in the presence of TC.The type of functional monomer and ratio of functional monomer to TC was optimized by density functional theory(DFT)simulation.The electrochemical sensor was successfully constructed by dropping the suspension of reduced graphene oxide and MSMIP on the glassy carbon electrode.Under the optimized conditions,the peak current was linear to TC concentration from 1.6×10-9 to 8.8×10-8 mol/L(R2 of 0.9996)and the detection limit was 9.16×10-10 mol/L.TC could be measured quickly in real milk samples using the as-prepared electrochemical sensor,and recovery rates ranged from 97.20%to 101.50%when standards were added.(3)A dual-signal electrochemical sensor was constructed using molecularly imprinted polymer(ATRP-MIP),which was prepared by atom transfer radical polymerization(ATRP)using magnetic MOFs material(Fe3O4@PDA@UiO-66NH2)as a carrier,as a recognition element.Au NPs were firstly modified on the electrode surface by electrodeposition to amplify the electrochemical signal,and then polythionine(PThi)was placed on the electrode surface in two steps by electrochemical method to provide a second detection signal.The MIP was prepared by ATRP polymerization in the presence methacrylic acid as functional monomer and SDZ as tamplate.After the SDZ was eluted by Soxhlet extraction,a large number of SDZ imprinting sites were left in the MIP.When the SDZ molecule was re-adsorbed,the oxidation peak currents of[Fe(CN)6]3-/4-(ISDZ)and PThi(IPThi)decrease simultaneously at 0.20 V and-0.30 V.By measuring the total current of the ATRP-MIP/PThi/Au/GCE sensor after binding SDZ(ID=ISDZ+IPThi),a high sensitivity detection of SDZ was achieved,and it has a good linear relationship between 4×10-8 to 4×10-6 mol/L and 4×10-6 to 1.1×10-4 mol/L,and the lowest detection limit is 5.82×10-9 mol/L.