DNA template-synthesized silver nanoparticles: A new platform for high-performance fluorescent biosensing of biothiols

To develop the high-performance fluorescent bio-sensors, the metal nanoparticles were employed as nanoquenchers and attracted reasonable attention in the design of fluorescent biosensors. In this work, silver nanoparticles (AgNPs) were obtained via reduction of Ag + on FAM-labeled DNA template. For the tight binding between AgNPs and DNA, the template-synthesized AgNPs turned out high quenching efficiency and could be applied as super nanoquenchers to establish the biosensing platform for fluorescent detection. As an example, the template-synthesized DNA-AgNPs conjugates were employed in sensing thiols. By forming S-Ag bonds, thiols interact intensely with AgNPs and replace the FAM-labeled DNA off from the surface of AgNPs, resulting in a fluorescence enhancement. Besides the advantages of lower background and higher signal-to-background ratio (S/B), the conjugates present better stability, making them applicable in complicated biological fluids. To further evidence the feasibility of sensing thiols in real samples, the thiols in human urine were detected. The total amount of free thiols found in human urine was ranging from 229 μM to 302 μM with the proposed sensor. To conclude the reliability, low content of Cys was added and the recovery was 98%–103%.