Enzyme activity termination by titanium carbide nanosheet and its application for the detection of deoxyribonuclease I.

Deoxyribonuclease I (DNase I) is a typical nuclease that plays key roles in many physiological processes and the development of a novel biosensing strategy for DNase I detection is of fundamental significance. In this study, a fluorescence biosensing nanoplatform based on a two-dimensional (2D) titanium carbide (TiC) nanosheet for sensitive and specific detection of DNase I was reported. Fluorophore-labeled single-stranded DNA (ssDNA) can be spontaneously and selectively adsorbed on TiC nanosheet through the hydrogen bond and metal chelate interaction between phosphate groups of ssDNA and titanium of TiC nanosheet, resulting in effective quenching of the fluorescence emitted by fluorophore. Notably, it was found the enzyme activity of DNase I will be terminated by the TiC nanosheet. Therefore, the fluorophore-labeled ssDNA was firstly digested by DNase I and the "post-mixing" strategy of TiC nanosheet was chosen to evaluate the enzyme activity of DNase I, which provided the possibility of improving the accuracy of the biosensing method. Experimental results demonstrated that this method can be utilized for quantitative analysis of DNase I activity and exhibited a low detection limit of 0.16 U/ml. Additionally, the evaluation of DNase I activity in human serum samples and the screening of inhibitors with this developed biosensing strategy were successfully realized, implying that it has high potential as a promising nanoplatform for nuclease analysis in bioanalytical and biomedical fields.