| Pollutants in water will enter the human body through accidental ingestion,skin contact,etc.,therefore,it is of great significance for human health to realize high sensitivity and selectivity detection of pollutants in water.Due to the advantages of visualization,easy preparation,rapid detection and without complex instruments,colorimetric sensing detection has attracted great interest of many researchers.The principle of colorimetric sensing is based on the action between recognition element and target,light response signal is generated during the reaction,and the analysis of the object can be measured.The main research direction of colorimetric sensing is high sensitivity and high selectivity detection of pollutants,which means the improvement of catalytic activity of nanomaterials and the specificity of the identification element and analyte.Compared with other nanomaterials,molybdenum disulfide（Mo S2）has been widely used in sensor detection because of its good catalytic activity and easy functionalization.However,the limited catalytic activity and the easily aggregated structure restrict the application of two-dimensional Mo S2.Hence,in order to improve the detection performance of the Mo S2-based colorimetric sensing system,this article aimed to improve the sensitivity and selectivity of colorimetric sensing platform based on Mo S2-Fe3O4 hydrogel,and screen aptamer of diphenyl phosphate.The main research contents and conclusions are as follows:（1）Mo S2-Fe3O4hydrogel with higher peroxidase-like activity was prepared by an easy preparation process of chemical co-precipitation,and realizing the sensitive detection of H2O2in the water through the construction of colorimetric sensors.In the H2O2-TMB color system,the generation of oxygen-containing free radicals by H2O2 is catalyzed by Mo S2 and Fe3O4synergistically.Meanwhile,the construction of hydrogel 3D structure can inhibit the stacking of Mo S2 nanosheets,which is benefit for the exposure of active sites,and highly enhanced peroxidase-like activity.The Mo S2-Fe3O4hydrogel with high catalytic velocity for substrates of H2O2,which is about 1.5 times higher than that of HRP.Based on high catalytic activity H2O2 detection was conducted with a linear relationship between absorbance and H2O2concentrations,ranging from 3.0 to 200μM,and the limit of detection（LOD）was 0.28μM（3σ/k）.In addition,the standard addition recovery method was used to detect H2O2 in tap water,lake and sea,and the recovery rate was 81.0%-98.2%,and the RSD value was0.4%-10.8%.（2）Retardant-diphenyl phosphate was chosen as target,which is one biomarker of organophosphorus flame,and the DNA aptamer was screened by immobilizing the nucleic acid library through magnetic bead method.After 12 rounds of SELEX selection,the elution efficiency of the screened products reached 1.4%,and we speculated that enrichment occurred.The screening products were subjected to high-throughput sequencing,and the sequencing results showed that the highest sequence repetition rate was as high as 1.04%.Three sequences with highest repetition rate were chosen to simulate the secondary structure,and speculate on their sites of action with the target.And through the SYBR Green I dye method to test the affinity,the result shows that the screening product has little affinity with diphenyl phosphate target,which laid the foundation for screening aptamers of enzyme-TPHP-M6complex,which is intermediate products of organophosphorus flame retardants during metabolic process. |
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