Optical Biosensing Technology Based On Gold Nanoparticles Colorimetry

Gold nanoparticles(Au NPs)have been widely used in sensors,catalysis,medical diagnosis and treatment,due to their excellent biocompatibility,adjustable surface modification performance and unique optical properties.The optical biosensing technology based on Au NPs has the advantages of simplicity,stability,and low cost,can achieve high-sensitivity detection of targets.The thesis analyzes the domestic and foreign research status of biosensing technology based on Au NPs.Aiming at the problem of lack of detection equipment in some areas,an optical biosensing method based on Au NPs colorimetry is proposed.Combining with dual-functional polystyrene nanospheres(PSs),which have both catalytic activity and bio-recognition functions,a colorimetric platform based on Au NPs is built to achieve highly sensitive optical biosensing of hepatitis B virus markers.This method does not require any complicated sample pretreatment or expensive detection equipment,and has broad prospects in clinical diagnosis,especially in resourcepoor areas.The specific work of this thesis is as follows:(1)Preparing and optimizing dual-functional PSs by a simultaneous coupling method,combined with the growth of Au NPs to realize the optical biosensing of hepatitis B virus marker-Hepatitis B surface antigen(HBs Ag).However,due to the competition between catalase and antibody during simultaneous coupling of PSs,the two functions of bifunctional PSs are not perfectly compatible,which resulting in the low detection sensitivity of this scheme.Therefore,it is necessary to improve the coupling method of bifunctional PSs.(2)Preparing and optimizing dual-functional PSs by a step-by-step coupling method,combined with the growth of Au NPs to realize the optical biosensing of HBs Ag.The naked eye detection limit of this scheme is 0.1 ng/m L,which is 3-4 orders of magnitude higher than the synchronous coupling method's.Measured by the microplate reader,the detection limit is 0.01 ng/m L(clinical requirement is 0.5 ng/m L),the linear range is 0.01-10 ng/m L,the recovery rate of HBs Ag spiked in serum is 93.44%-104.67%,and the relative standard deviation is 0.04%-3.61%.It can be seen that the bifunctional PSs prepared by step-by-step coupling method can significantly inhibit the competition during simultaneous coupling,which greatly improving the detection sensitivity of the targets.And the scheme has high specificity,reproducibility and stability,can apply in serum well.(3)Based on the dual-functional PSs with step-by-step coupling method and crosslinking aggregation of Au NPs,the optical biosensing of HBs Ag can be achieved.The naked eye detection limit of this scheme is 1 ng/m L.Measured by the microplate reader,the detection limit is 0.01 ng/m L,the linear range is 0.5-20 ng/m L,the recovery rate of HBs Ag spiked in serum is 97.54%-113.46%,and the relative standard deviation is2.01%-4.52%.It can be seen that the scheme has high specificity,reproducibility and stability,can apply in serum well.It is beneficial to combine microfluidic chips in the future.