Snowflake-like DNA crystals templated Cu clusters as a fluorescent turn-on probe for sensing actin

Herein, we synthesized snowflake-like DNA crystals (SDC) via hybridization chain reaction and used it for the first time in the synthesis of copper nanoclusters with enhanced fluorescence. Atomic force microscopy (AFM) and laser confocal microscopy characterization confirmed that SDC/CuNCs are self-assembled successfully on SDC. Aggregation induced emission allows SDC/CuNCs to exhibit better stability and stronger emission intensity. Thus, we developed the "turn-on" label-free fluorescence detection method of actin based on SDC/CuNCs which offer simplicity, low cost, good selectivity, and high sensitivity. The detection limit was determined to be 0.0124 μg mL^-1, which was an order of magnitude lower than that of reported fluorescent methods (0.12 μg mL^-1). Compared with previous method, the linear range is also much wider. We also performed standard recovery experiments in actual samples for evaluating the practicality of this strategy and proved that the capability of the proposed approach for the determination of actin is feasible and the interference from complex biological samples is negligible. These results indicate that SDC/CuNCs are expected to play a more important role in the field of biosensors.