Polystyrene spheres coated with gold nanoparticles for detection of DNA.

A novel method has been developed here utilizing gold-modified polystyrene spheres (PS@Au) as carriers for the investigation of DNA hybridization. The immobilization ability of DNA probes on the PS@Au was investigated by a quartz crystal microbalance (QCM). More gold nanoparticles (AuNPs) were conjugated to the QCM surface in the form of PS@Au as compared with the AuNPs alone. The influence of PS, AuNPs population and size on the DNA probe fixation, and hybridization has been investigated. The results show that more AuNPs were achievable onto the QCM surface and could greatly increase the immobilization amount further hybridization amount of DNA. There was an optimal surface curvature for the probe DNA absorption. The curvature about 12 nm was more suited to the adsorption of probe DNA which could lead to the detection limit further down to 10(-12) M. These results demonstrate that the introduction of PS@Au, with polystyrene spheres as the medium between the QCM surface and the AuNPs, could achieve modified QCM surfaces and increase its detection ability for a better DNA assay and a novel platform for the fabrication of DNA sensors.