DNA-Templated In Situ Synthesis of Highly Dispersed AuNPs on Nitrogen-Doped Graphene for Real-Time Electrochemical Monitoring of Nitric Oxide Released from Live Cancer Cells.

Dispersion promotion of nanomaterials can significantly enhance their catalytic activities. With a new DNA-templated in situ synthesis approach, we report the preparation of highly dispersed AuNPs on nitrogen-doped graphene sheets (NGS) with significantly improved electrocatalytic ability for the monitoring of nitric oxide (NO) released from live cancer cells. The template DNA is adsorbed on NGS via π-π stacking, and the Au precursor chelates along the DNA lattice through dative bonding. Subsequent introduction of the reducing agent leads to in situ nucleation and growth of AuNPs, eventually resulting in highly dispersed AuNPs on NGS. Because of the synergistic enhancement of the catalytic activities of AuNPs and NGS, as well as the high dispersion of AuNPs, such a nanocomposite shows significant electro-oxidation capability toward NO, leading to a highly sensitive subnanomolar detection limit for NO in vitro. More importantly, the laminin glycoproteins can be readily adsorbed on the surface of the nanomaterials to render excellent biocompatibility for the adhesion and proliferation of live cells, enabling the biointerface for electrochemical detection of NO released from live cancer cells.