Dual Signal Amplification by Urease Catalysis and Silver Nanoparticles for Ultrasensitive Colorimetric Detection of Nucleic Acids

Signal amplification techniques are highly desirablefor the analysisof low-level targets that are closely related with diseases and themonitoring of important biological processes. However, it is stillchallenging to achieve this goal in a facile and economical way. Herein,we developed a novel dual signal amplification strategy by combiningurease catalysis with the release of Ag+ from silver nanoparticles(AgNPs). This strategy was used for quantifying a DNA sequence (HIV-1)related with human immunodeficiency virus (HIV). DNA target HIV-1hybridizes with the capture DNA probe on magnetic beads and the reporterDNA probe on AgNPs, forming a sandwich complex. The captured AgNPsare then transformed into numerous Ag+ ions that inactivatenumerous ureases. Without catalytic production of ammonia from urea,the substrate solution shows a low pH 5.8 that will increase otherwise.The pH change is monitored by a pH indicator (phenol red), which allowsfor colorimetric detection. The proposed approach is sensitive, easyto use, economic, and universal, exhibiting a low detection limitof 9.7 fM (i.e., 1.94 attomoles) and a dynamic linear range of 4 ordersfor HIV-1 sequence detection.

Automated summary

A novel dual signal amplification strategy was developed for the detection of HIV-1 DNA sequence. This approach combines urease catalysis with the release of Ag+ from silver nanoparticles, allowing for sensitive and economical quantification. The proposed method exhibits a low detection limit and a wide dynamic linear range.