Developing a novel and simple biosensor for Cystatin C as a fascinating marker of glomerular filtration rate with DNase I-aided recycling amplification strategy.

Cystatin C (Cys C) has been proposed as a fascinating glomerular filtration rate (GFR) marker for early detection of acute kidney injury and chronic kidney disease. However, most of traditional methods for Cys C detection are immunoassays, which was tedious to perform and unfriendly for economics. In this work, a novel and simple biosensor for the sensitive measurement of Cys C via DNase I-aided recycling amplification strategy was successfully constructed based on the graphene oxide (GO) and fluorophore-labelled aptamer, which can be used to the early prediction of kidney injury. The fluorescence of fluorophore-labelled aptamer was quenched by GO based on the Fluorescence Resonance Energy Transfer (FRET) and recovered with the existence of Cys C. In addition, the DNase I enzyme would digest the fluorophore-labelled aptamer and dissociate the Cys C to launch the next reaction, resulting in an increase of signal amplification. Hence, the limit of detection is found to be 0.16 ng mL-1, which is almost 3 times lower than that without DNase I. Consequently, the developed biosensor offers a novel approach towards simple and rapid detection of Cys C based on the integration of GO and aptamer. Conceivably, this strategy holds a wide scope in the application of numerous other analytes if corresponding aptamers are available.