A signal-on, colorimetric determination of deoxyribonuclease I activity utilizing the photoinduced synthesis of gold nanoparticles

and threonine (Thr), forms AuNPs by UV light irradiation with the aid of Thr which acts as a catalyst for the Au(iii) reduction process. As a result, a red-colored suspension is produced. By monitoring the color changes of the samples with the naked eye, the DNase I activity was conveniently determined. In addition, the clinical utility of this simple, yet highly efficient colorimetric strategy was verified by reliably quantifying the DNase I activities in a bovine urine sample. Importantly, the working principle designed for the determination of DNase I activity was successfully expanded for the detection of target nucleic acids, ensuring the universal applicability of the developed assay system.