A novel signal transduction system for development of uric acid biosensors.

Uric acid (UA) is an important biomarker for clinical diagnosis. Here, we present a novel signal transduction system for the development of UA biosensors with the characteristics of stability and ease-of-use. In this system, bacterial allosteric transcription factor HucR was used as the bio-recognition element, and the competition between HucR and the restriction endonuclease HindIII-HF to bind to the designed DNA template was employed to enable signal transduction of UA recognized by HucR. The presence of UA can induce conformational change of HucR, which dissociates HucR from the designed DNA template, allowing the access of the competitor HindIII-HF to cut this DNA template. Thus, the signal of UA recognized by HucR is transduced to easily detectable DNA signal. As proof-of-concept, we demonstrated two UA biosensors by coupling this signal transduction system with real-time quantitative PCR (RT-qPCR) and amplified luminescent proximity homogeneous assay (Alpha), respectively. The RT-qPCR-based UA biosensor has a detection limit of 5 nM with a linear range up to 300 nM UA; Alpha-based UA biosensor has a detection limit of 30 nM with a linear range of 100 nM-10 μM. Moreover, the robustness of both biosensors was verified by reliably detecting UA present in a human serum sample. Altogether, the novel UA biosensors developed in this work hold great potential for clinical application.