Coassembly of Gold Nanoclusters with Nucleic Acids: Sensing, Bioimaging, and Gene Transfection

Abstract Assemblies of biopolymers and nanomaterials have become a powerful tool to build up new architectures with growing application potential. Herein, novel peptide‐stabilized fluorescent gold nanoclusters, K4‐AuNCs, are utilized as building blocks to investigate their coassembly with nucleic acids. K4‐AuNCs possess ultrasmall size (1.8 nm), red fluorescence emission, and positively charged surfaces, which are able to coassemble with DNA or RNA strands through electrostatic interactions to form pitaya‐like hybrid nanoparticles ranging from 30 to 80 nm, accompanied by an up to 3.5‐fold fluorescence enhancement. The coassembly also forms intracellularly, rendering K4‐AuNCs an attractive dye for specific in vivo nucleic acid staining, due to their higher photostability than commercial fluorescent probes such as SYTO 9. This work also demonstrates that the coassembly of K4‐AuNCs with nucleic acids can be applied to gene transfection and to build up a sensing platform to detect DNase/RNase activity or to screen their inhibitors. The new strategy greatly extends the application range of gold nanoclusters into the development of new nucleic acid detection methods and novel hybrid materials.