Bioassay Method Based On Single Gold Nanoparticle Detection

Gold nanoparticles are very easy to prepare and modify and exhibit excellent optical properties.Therefore,they have been attracted a wide spread attention by researchers and a lot of practical applications in bioassay and imaging have been developed.The main content of this paper is to develop the ultrahigh sensitive and rapid homogeneous bioassay based on the utilization of single-countable gold nanoparticle.The details are shown as follows:First,two kinds of most widely used gold nanoparticles-gold nanospheres and gold nanorods-were prepared and characterized.To accurately mearsure the concentration,a enrichment detection method based on electrostatic confinement was developed to absolutely quantify the nanoparticles even in extremely low abundance.Second,we have developed a novel ultrahigh sensitive bioassay method based on non-colocation enrichment.This method relies the magnetic beads to capture target molecules and gold nanorods to label the target molecules.The target molecules are replaced by gold nanorods in 1:1 ratio using magnetic screening and separation.Combined with the absolute quantification of gold nanorods,the inevitable challenge of low sampling rate in the conventional in-situ detection mode was solved.We applied this method for the detection of DNA and protein and obtained ultrahigh sensitivity.Third,a class of homogeneous,rapid,‘ mix and detection',highly sensitive bioassay methods has been developed.One of this method measures the difference of scattering intensity between single gold nanorod and its aggregate(induced by the addition of target molecule)to quantify the target.The other method replaces the target molecules with gold nanorods in a 1:1 ration by means of the introduction of magnetic beads and aptamers.The absolute quantification of gold nanorods is used to quantify the target.