Anti-biofouling laser-scribed graphene electrochemical sensor for reliable detection of uric acid in human saliva

The direct detection of uric acid (UA) in unprocessed raw saliva by electrochemical sensors is usually a challenge because of the strong biofouling effect of some mucoproteins. Here, a disposable and anti-biofouling graphene electrochemical sensor for the detection of UA in human saliva is reported. The sensor was fabricated by the modification of a composite of BSA and Tween-20 (BSAT) on laser-induced graphene (LIG) electrodes via drop casting. This modification method produces an ultrathin BSAT coating on the sidewall of porous LIG sheets via possible hydrophobic interactions, which apparently improves the hydrophilicity and anti-biofouling ability of the LIG-based sensor. The structural and electrochemical properties of the BSAT coating were investigated by various techniques, and electrode kinetics-dependent electrochemical behaviors of various electroactive probes were observed. Under optimal conditions, the UA sensor possesses a calibration range of 20.0 ∼ 1000 μM and a detection limit of 2.1 μM (S/N = 3), which was successfully applied to the detection of UA in 5-fold diluted human raw saliva under different physiological conditions.