A novel high-stability bioelectrochemical sensor based on sol-gel immobilization of lactate dehydrogenase and AuNPs-rGO signal enhancement for serum pyruvate detection

Pyruvate participates in diverse metabolic pathways in the body and is normally present in human blood at 40–120 μM, with concentrations outside this range associated with various diseases. Therefore, accurate and stable blood pyruvate level tests are necessary for effective disease detection. However, traditional analytical techniques require complicated instrumentation and are time consuming and expensive, prompting researchers to develop improved methods based on biosensors and bioassays. Here, we designed a highly stable bioelectrochemical pyruvate sensor affixed to a glassy carbon electrode (GCE). To maximize biosensor stability, 0.1 U of lactate dehydrogenase was affixed to the GCE using a sol-gel process, resulting in generation of Gel/LDH/GCE. Next, 2.0 mg/mL AuNPs-rGO was added to enhance current signal strength, resulting in generation of the bioelectrochemical sensor Gel/AuNPs-rGO/LDH/GCE. AuNPs-rGO synthesized in advance was verified as correct using transmission electron microscopy and UV–Vis, Fourier-transform infrared and X-ray photoelectron spectroscopy. Pyruvate detection conducted via differential pulse voltammetry in phosphate buffer (pH 7.4, 100 mM) at 37 °C for 1–4500 μM pyruvate provided detection sensitivity as high as 254.54 μA/mM/cm2. The reproducibility, regenerability and storage stability were analyzed with the relative standard deviation of 5 bioeletrochemical sensors detection was 4.60% and biosensor accuracy after 9 cycles was 92%, with accuracy remaining at 86% after 7 days. In the presence of D-glucose, citric acid, dopamine, uric acid and ascorbic acid, the Gel/AuNPs-rGO/LDH/GCE sensor exhibited excellent stability, high anti-interference ability and better performance than conventional spectroscopic methods for detection of pyruvate in artificial serum.