Gold Nanoparticles Enhanced Surface Plasmon Resonance Biosensor

In recent years,a variety of new types of biosensors is emerging,and has been widely used.The SPR biosensor represents the most advanced and mature label-free optical biosensor technique,which can detect the biomolecular interactions dynamics directly,real-time,rapidly and without markers or staining.Thus,it is widely used in the fields of biomolecular interactions detection,clinical diagnostics,food and environment monitoring,and so on.However,as the continuous research directions expanding and the research contents deepening,people have higher requirements about the conditions and level of the SPR biosensor detection,especially for the detection sensitivity improving.Gold nanoparticles(AuNPs)have unique optical and electrical properties,good biocompatibility,easy modification and other characteristics.As a result,it has been used in many fields,such as optical,catalytic and biological science.Its localized surface plasmon resonance(LSPR)feature is one of the most interesting features and makes it a superior support for new biological and chemical sensors.The strong affinity of the interaction between poly adenine(poly A)and gold,can match with the chemical affinity for Au-S,and preferentially adsorbed on the gold surface.We can control the DNA grafting density,structure and reduce the non-specific adsorption of DNA to improve the reproducibility of the experiment,by controlling the length of the anchor poly A sequence.In this work,we use seed-growth method for AuNPs synthesis,and obtain four kinds of AuNPs with different particle diameter with relatively narrow size distribution.Then,we immobilize two kinds DNA on the gold substrate or AuNPs via the interaction between the poly A and gold,the extending section of which are complementary.We successfully immobilized DNA on Au substrate and AuNPs,controlling the density of DNA by poly A,and explore them hybridization behavior with target DNA.At last,we use a sandwich structure,binding the AuNPs on the surface of SPR biosensor to enhance the traditional SPR signal,through the complementary hybridization between the DNA section that respectively immobilized on the AuNPs and the gold substrate.We also researched the effect of different conditions for enhancement of SPR.