Protein-inorganic hybrid flowers with a two-stage accelerated strategy for stimulated activation of CRISPR/Cas12a enhance polynucleotide kinase biosensing.

Polynucleotide kinases (PNK) play a crucial role in DNA damage repair and are closely associated with specific diseases, making them promising targets for therapeutic intervention. In this study, we propose a two-stage accelerated strategy that utilizes protein-inorganic hybrid flowers (PHFs) to enhance the performance of the terminal deoxynucleotidyl transferase (TdT)-combined CRISPR/Cas12a system (TCS) for efficient detection of PNK activity. In TCS, the participation of PHFs confines the substrate probes (SPs) to a limited space, thereby significantly enhancing the local concentration of phosphorylated 3' termini of SPs and effectively promoting the enzymatic reaction kinetics as the first step in the accelerated strategy. Upon encountering the target PNK, the phosphorylated 3' termini were promptly recognized and dephosphorylated to 3'-OH termini. Subsequently, TdT catalyzed the assembly of deoxyadenosine triphosphates (dATPs) without a template, rapidly activating the CRISPR/Cas12a system by forming multiple polyadenine (poly-A) chains. PHF-fixed poly-A chains then substantially boosted the localized concentration of CRISPR/Cas12a systems and vastly enhanced their efficacy in cleaving reporter nucleic acids. Our findings indicated that the spatial confinement effect facilitated by PHFs promoted frequent molecular collisions and accelerated multiple enzymatic reactions. The developed sensing strategy allows for the detection of PNK activity within a linear range of 0.001-1 U/mL, with a detection limit of 1.82 × 10 U/mL. Additionally, this strategy has been successfully applied to detect PNK activity in cell extracts and to screen for PNK inhibitors. Owing to these advantages, PNK can be rapidly and accurately detected with a high sensitivity, specificity, and biostability.