Actin inhibited nuclease digestion of DNA-templated silver nanoclusters and the application for fluorescent biosensing

Actin is one of the key proteins expressed in cellular life activities, which is also closely related with many human diseases. Herein, we develop a novel fluorescent method for globular actin (G-actin) assay based on the inhibition of nuclease-cleaved silver nanoclusters (AgNCs). The pristine DNA-templated AgNCs feature a fluorescence transition from green (Ag 13/14 NCs) to red (recombined Ag 10 NCs) triggered by the cleavage of deoxyribonuclease I (DNase I). In the presence of target G-actin, a stable complex forms by the interaction between G-actin and DNase I, thereby inhibiting the cleavage activity and subsequent fluorescence transition. Through monitoring the regulation of fluorescence emission, we ultimately achieve quantitative detection of G-actin. The proposed AgNCs based sensor is highly efficient and sensitive. It is also successfully applied to distinguish normal and cancer cells by measuring G-actin levels. This study not only provides a unique strategy for actin-based applications, but also inspires the engineering of DNA-templated nanomaterials.