Preparation Of Self-assembled Molecularly Imprinted Nanoparticles And Its Applications In Sensors

Molecularly imprinted polymers?MIPs?are a kind of“artificial antibody”with binding sites that are complementary with template in shape,size and functional groups and could bind templates specifically.MIPs have become the substitute of bioactive substances?antibodies and enzymes?in practical applications owning to their lower price and better environmental stability.Compared with traditional MIPs,nano-sized MIPs have higher surface-volume ratio,more binding sites close to their surface and lower mass transfer resistance during the extraction and rebinding procedure.However,most nano-sized MIPs were prepared in organic solvents,leading to the inefficient recognition in aqueous solution where the determination of bioactive molecules occurs.So,it's high time to develop water dispersible nano-sized MIPs.According to the previous study of our group,water dispersible molecularly imprinted nanoparticles?MIP NPs?could be prepared via the co-assembly of amphiphilic copolymers and templates in aqueous solution.The MIP NPs were further applied to construct molecularly imprinted electrochemical sensors which could recognize templates in aqueous solution.However,these amphiphilic copolymers didn't possess any fluorescent or electrical properties,leading to the lack of responsive capacities of MIP NPs to templates;that is to say,MIP NPs couldn't realize the sensitive detection of templates due to the lack of detectable signals after template recognition.In this paper,water dispersible MIP NPs with both recognition and responsive capacities were prepared via the combination of molecularly imprinting technology,assembly and the introduction of responsive moieties.Templates recognition procedure could be transferred into detectable signals by the coupling of molecularly imprinting technology and responsiveness.The work includes the following parts:?1?The preparation of molecularly imprinted PANI NPs via co-assembly and its application in MIP sensorThe random amphiphilic copolymer P?AMPS-co-St?with 2-acrylamido-2-methyl propane sulfonic acid and styrene in its back born was synthesized firstly.The water dispersible PANI NPs were prepared by the co-assembly of P?AMPS-co-St?and PANI in aqueous solution.It turned out that the diameter of PANI NPs could be adjusted by varying the structure parameter of P?AMPS-co-St?and the content of PANI in PANI NPs.Ovalbumin?OVA?was added into the co-assembly system as template,which could be embedded into PANI NPs by hydrogen binding for the preparation of molecularly imprinted PANI nanoparticles?MIP-PANI NPs?.Then,MIP-PANI NPs were modified on the electrode;after template removal,molecularly imprinted PANI sensor?MIP-PANI sensor?was fabricated.The effects of the thickness of molecularly imprinted film on the surface of MIP-PANI sensor and OVA concentration on detection performance were further studied.The results showed that MIP-PANI sensor had good selectivity to templates in aqueous solution,a linear detection range of 10^-1110^-6 mg mL^-1 and a detection limit of 10^-12 mg m L^-1.?2?The preparation of fluorescent molecularly imprinted nanoparticles via co-assembly and its applicationThe random amphiphilic copolymer P?AA-co-NVC?with fluorescent moiety carbazole and hydrophilic acrylic acid in its back born was synthesized,then PANV-GMA was prepared by applying glycidyl methacrylate for the partly modification of carboxylic groups to introduce double bonds into the copolymer.Induced by water,PANV-GMA,cross-linker?divinyl benzene,DVB?and photo-initiator?dimethoxybenzoin,DMPA?could co-assemble by hydrophobic interaction,and the template?paracetamol,PCM?could be embedded into the nanoparticles for the preparation of crosslinkable MIP NPs.The fluorescent molecularly imprinted nanoparticles?FMIP NPs?were prepared via interior cross-linking induced by UV-light and template removal.The effects of the content of carbazole group of PANV-GMA,PCM concentration,DVB amount and pH on size and determination performance of FMIP NPs were further studied.It turned out that the particle size of FMIP NPs could be adjusted by varying PCM concentration,DVB amount and p H,and the prepared FMIP nanoparticles had good selectivity to PCM in aqueous solution,a linear detection range of 4.0×10^-61.0×10^-3 mol L^-1and a detection limit of 6.0×10^-7 mol L^-1.