Ce(III)-modulation over non-enzymatic Pt/CeO2/GO biosensor with outstanding sensitivity and stability for lactic acid detection

A series of non-enzymatic graphene functionalized biosensors was developed via deposition precipitation method for lactic acid (LA) detection, which were characterized by transmission electron microscopy (TEM), Raman spectroscopy , X-ray photoelectron spectroscopy (XPS), gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry, and proton nuclear magnetic resonance ( 1 H NMR). The electrochemical performances of the non-enzymatic biosensors were measured by means of the electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) method. The comprehensive analysis of structures shows that Pt, CeO 2 , and GO components interact with each other. During the storing and releasing oxygen, the valence ratio of Ce 3+ /Ce 4+ and the number of oxygen vacancies in CeO 2 change accordingly, which can be conducive to increasing electronic transmission capacity and finally leads to the improvement of electrocatalytic performance. Among them, the Pt/CeO 2 /GO biosensor containing 0.47 at% platinum exhibits an excellent electrochemical detection performance with high sensitivity of 12.3 µA·L/ (mmol·cm 2 ) and a low limit of detection (LOD) of 5.12 μmol/L in a wide linear range from 10 to 900 μmol/L. In addition, the proposed biosensor possesses a promising anti-interference capability, as well as high stability and good reproducibility, which was assessed by testing the cyclic voltammogram in 0.1 mol/L lactic acid one year later. The underlying mechanism was proposed for electrochemical oxidation of LA to carbon dioxide and acetic acid with the synergistic effect among Pt, CeO 2 , and GO. Furthermore, the results of the standard addition method in real samples (human serum and urine samples) reveal that the lactic acid detection of the non-enzymatic Pt/CeO 2 /GO biosensor is accompanied by high reliability. Thus, it will be a valuable biosensor for in vitro detection of lactic acid level in clinical samples.