The Interaction Between Gold Nanoparticles With DNA And Application In The Detection Of Human P53 Gene Mutation

Gold nanoparticles(GNPs) have many unusual chemical and physical properties such as unique optical effects,novel electrical effects and excellent biological affinity. Gold nanoparticles not only are widely used in the catalysis,self-assembly, microelectronics,sensors fields,but also show broad prospects in the biomedical field, such as biological label,nucleic acid detection,gene amplification,drug delivery,and transcription regulation.Therefore,gold nanoparicles have attracted considerable attention in recent years and become an important tool in genetic engineering.This article mainly studied the interaction of gold nanoparticles with single-stranded DNA and application in the detection of human p53 gene mutations.The synthesis and characterization of gold nanoparticles is very important for both fundamental and applied research.It is difficult to obtain stable and controlled gold nanoparticles in size and shape due to many factors.Through introducing different reducing methods and changing the concentration of reducing agent,we successfully synthesized three kinds of gold nanoparticles of 5 nm,13 nm,and 50 nm in size,which colors appeared brown,red,and yellow,respectively.The shape and size of gold nanoparticles were characterized by UV-Vis absorption spectrum and transmission electron microscope(TEM).The excellent bioaffinity is the foundation for the application of gold nanoparticles in biolabel,nucleic acid detection,and genetic engineering.The research of the interaction between gold nanoparticles and DNA is important for realizing the mechanism of the interaction and boarding the application of gold nanoparticles in biomedical fields.We choosed gold nanoparticles of 13 nm in this research.The experimental data showed that gold nanoparticles could aggregate after adding NaCl or NaOH and dissolve after acidification with HCl.Both processes were irreversible.If the same particles were incubated with singe strand DNA(ssDNA), GNPs-ssDNA complex were stable against NaCl-induced or NaOH-induced aggregation and assembled only when HCl was added,but redispersed when NaOH wass added.Four different types of dNTPs exhibited different binding affinity to gold nanoparticles in the order of dATP＞dGTP＞dCTP＞dTTP.The order of the polynucleotides was consistent with dNTPs(poly A₃₀＞poly G₃₀＞poly C₃₀＞poly T₃₀).Moreover,longer ssDNA had stronger protective effect to gold nanoparticles.Gold nanoparticles are unique tools for biomolecule detection and provide novel idea for gene mutation detection.Based on the different binding affinities between single-strand DNA and double-strand DNA(dsDNA) to gold nanoparticles,two novel methods were established to detect the p53 gene mutations successfully.