Positively Charged Nanogold Combined With Mesoporous Silica-based Immunoassay For The Detection Of Avermectin

With the improvement of people's lives,the requirements for the quality of life are continuous to increase,especially for food safety requirements.Avermectin,as an agricultural veterinary drug,is one of the most widely used agricultural and veterinary drugs so far.However,it may remain in the food.Therefore,it is necessary to establish a rapid and effective method for detecting avermectin.In this study,modified avermectin was used to immunize New Zealand white rabbits to obtain polyclonal antibodies.Moreover,the positively charged nano-gold coated with mesoporous silica was combined with the obtained polyclonal antibody to establish an avermectin residue detection strategy.First,avermectin was modified through chemical synthesis method to make it easier to couple the protein,and then then coupled with the bovine serum protein and ovalbumin via carbodiimide method to obtain immune antigen and coating antigen.Next,polyclonal antibodies were obtained by immunizing New Zealand white rabbits with immune antigen.In addition,we prepared positively-charged nanomaterials through chemical synthesis and added mesoporous silica as a carrier to overcome the aggregation and precipitation of positively-charged nanogold.Infrared spectroscopy was used to verify the successful synthesis of avermectin modification,and UV absorption spectrum and SDS-PAGE were used to identify the successful synthesis of immune and coated antigens of avermectin.Scanning electron microscopy,transmission electron microscopy,element mapping,N₂adsorption-desorption,X-ray diffraction,energy dispersive X-ray,and Zeta potentiometer were used to verify the successful synthesis of nanomaterials.A positively charged nano-gold immunoassay based on mesoporous silica for the detection of avermectin residues in food was established in this work.Under the optimized conditions,standard curves based on mesoporous silica based positively charged nanogold immunoassay and enzyme-linked immunoassay for the detection of avermectin were constructed.For the enzyme-linked immunoassay method,the IC₅₀value is 56.29 ng/m L,the LOD is 6.14 ng/m L,and the linear range is 7.68–412.49 ng/m L.For the positively charged nanogold immunoassay based on mesoporous silica The IC₅₀value is 21.61 ng/m L,the LOD is 2.17 ng/m L,and the linear range is 2.53-184.28 ng/m L.The results show that the positively charged nanogold immunoassay based on mesoporous silica is more sensitive than the enzyme-linked immunosorbent assay.Moreover,specificity experiments and sample recovery experiments proved that this method has high specificity and high recovery rate.Furthermore,compared with HPLC,this method has high accuracy.In general,the developed mesoporous dioxide-based positively charged nano-gold immunoassay of silicon has proven to be an effective method for detecting avermectin in animal tissues.