Abstract:Based on T-Hg2+-T structure for specific recognition and the tandem intermolecular splitting G-quadruplex-hemin DNAzymes nanowires for catalytic signal amplification, a highly sensitive "Turn-on" biosensor for detection of Hg2+ was developed on the polystyrene microbeads using the hybridization chain reaction. When Hg2+ was present in reaction system, the formation of T-Hg2+-T special structure prompted T-rich DNA probes modified on the microbeads to open and capture the designed hairpin probe P1, which triggered the hybridization chain reaction between hairpin probe P1 and hairpin probe P2. Since the 5’ free terminal and the 3’ free terminal of hairpin probe P1 and P2 both contain the G-rich sequences which are contacted closely with each other and arranged in series through hybridization chain reaction, and the neighbouring G-rich sequences further fold to form autonomously assembled nanowires containing tandem intermolecular splitting G-quardruplex-hemin DNAzyme on the interface of polystyrene microspheres. Under the optimal experimental conditions, the linear range for detection of Hg2+ was 2 pmol/L-1 nmol/L, and the detection limit was 1.5 pmol / L. The sensor still has a high selectivity to Hg2+ when the coexisting ions in the sample are abundant. The sensor had good selectivity, sensitivity, and stability for Hg2+ analysis.