Biomolecular sensing via coupling DNA-based recognition with gold nanoparticles

Gold nanoparticles (AuNPs) have been extensively employed to develop novel nanobiosensors based on their unique optical properties. Here we first describe the unique localized surface plasmon resonance properties of AuNPs, which can be finely tuned via the aggregation of AuNPs and disassembly of AuNP aggregates. We then review the applications of both AuNPs-DNA conjugates and unmodified AuNPs in selective detection of a variety of molecular targets, including DNA, proteins, small molecules and ions, by incorporating DNA hybridization or aptamer-target binding. In many situations, target-induced assembly and disassembly lead to a characteristic red/blue colour change that arises from the shift of surface plasmon resonance absorption of AuNPs. The superquenching ability of AuNPs and its application in fluorescent sensors are also discussed.