Application Of Surface Imprinting Technology In Rapid Detection Of Typical Marine Environmental Pollutants

Marine environment is seriously polluted by various organic pollutants such as antibiotic drugs from aquaculture and marine biotoxins produced by harmful algal blooms,which threaten human health through the food chain due to biological accumulation in the ocean.For the food safety,the effective quantification of these pollutants in marine environmental samples is of great significance to ensure that the concentration is below the legal level.In this paper,a variety of new core-shell imprinted polymers were prepared by surface imprinting method using Fe3O4@SiO2,carbon dots and other nanoparticles as nuclear support substrates.With dual advantages of molecular imprinting technology and photometric analysis,magnetic imprinting extraction procedures and a carbon dots-based imprinted fluorescent sensor were developed for the selective and sensitive detection of malachite green(MG),oxytetracycline(OTC)and okadaic acid(OA)in the marine environment.The main contents and results of this paper are as follows:1.A new type of magnetic molecularly imprinted nanoparticles was designed and prepared by surface imprinting method using Fe3O4@SiO2 as the support.The polymers at each step were thoroughly studied based on transmission electron microscopy,FTIR spectroscopy and thermogravimetric analysis.Simultaneously,adsorption performances of the resultant nanoparticles were analyzed in detail and extremely excellent affinity with the MG was revealed.Further,the main parameters of magnetic molecular imprinted solid-phase extraction(MMIP-SPE)were screened by multivariate optimization methods.The magnetic nanoparticles were used as special adsorbents to directly extract MG from crude marine sediment extracts,and a selective preconcentration and detection of MG followed with UV-Vis spectrophotometry from marine sediment samples was realized under the optimal MMIP-SPE conditions.The limits of detection(LOD)and limits of quantification(LOQ)were respectively 2.5 and 8.3 ?g L-1 for MG,and the wide linear range of 0.25?50 mg L-1(R2=0.997).The developed method exhibits satisfactory recoveries from the spiked samples,ranging from 80.4 to 93.0%with an RSD of less than 5.18%(n=3).This simple and rapid method is expected to lead to new approaches for the specific separation and enrichment of MG from complex marine environmental matrix without the need for complex equipment.2.A fast and sensitive trace determination method was developed for the rapid analysis of OTC in natural seawater samples of surface seawater.By means of co-precipitation and sol-gel method,Fe3O4@SiO2 was obtained.Subsequently,the OTC magnetic imprinting material was fabricated via surface imprinting polymerization to embed Fe3O4@SiO2 as the sacrificial matrix and the dummy imprinting strategy.The dummy template strategy effectively solves the problem of template leakage and incomplete elution during the adsorption process.The simplicity of the material was provided by centrifugal-free powerful magnetism,and the selectivity and sensitivity of the detection method were guaranteed by a core-shell structure with the imprinting layer and fluorescence analysis.The LOD and LOQ of this method were 0.7 and 2.3 ?g L-1,respectively.The recoveries of the spiked samples were 89.8-107.7%with relative standard deviation values of less than 5.44%(n=3).3.Based on the principle of PET recognition,a dual-emitting fluorescence MIPs nanosensor with CDs@SiO2 as a nuclear carrier was ingeniously fabricated and successfully applied in rapid and sensitive detection of OA from seawater and sediment samples.The eco-friendly CDs obtained by hydrothermal treatment of plant leaves were employed as interior label,and the conjugates of 3-amino-propyltriethoxysilane and nitrobenzoxadiazole(APTES-NBD)played the role of signal recognition unit.The imprinted polymeric shell for OA was formed around the CDs@SiO2 by copolymerization method and then the characterization and binding properties of the MIPs were systematically investigated.The MIPs sensor can selectively rebind the analyte with the addition of OA and the fluorescence intensity of NBD will rapidly be enhanced along with changes of the hybrid fluorescence color,eventually to realize the visual detection of OA.The results showed that a linear fluorescence enhancement response in the range of 100?1770 ng L-1 was achieved with a limit of detection of 25.20 ng L-1 and the recoveries ranged from 90.0%to 107.0%with precisions below 4.11%(n=3).More importantly,a reliable visual sense change can be clearly observed by the naked eyes during the fluorescence analysis,which provides potential applications of molecularly imprinted sensors in trace analysis of marine environmental matrix.In this paper,MG,OTC and OA,which are common organic pollutants in marine environment,were selected as the research objects.The combination of magnetic base or carbon quantum dot base and molecular imprinting technology was mainly discussed,and core-shell imprinted nanoparticles with specific recognition were synthesized by surface imprinting technology.The core-shell imprinted nanoparticles made the imprinting site at or close to the surface,which increased the effective imprinting site,increased the imprinting capacity,accelerated the mass transfer rate,and was conducive to the diffusion and elution of template molecules.The use of magnetic materials as a support eliminated the need for suction filtration or centrifugation in the process of separating the polymer from the solution,saving time and simple operation.Ratio fluorescence molecularly imprinted polymers,which combine high selectivity and sensitivity,can output visual detection signal while high selectivity recognition,and can be used for rapid analysis of actual samples.This simple,reliable and sensitive analytical strategy holds great potential for rapid and highly selective detection of trace small molecular organic pollutants in complex substrates.