Gold Microflower Modified Screen-Printed Carbon Electrode for the Electrochemical Detection of Lactic Acid in Blood and Sweat

A nonenzymatic electrochemical lactic acid sensor was fabricated by electrodepositing gold microflowers on a screen-printed carbon electrode and used to determine lactic acid in human serum and sweat quantitatively. Extensive voltammetric studies with lactic acid in phosphate-buffer saline (PBS) and the analysis of the reduction product proved beyond doubt that lactic acid undergoes two-electron reduction to form lactaldehyde. The reduction current increased quantitively with lactic acid concentration from 0.5-8.5 mM in 0.1 M PBS. The sensor showed excellent sensitivities of 1243 mu A mM-1 cm-2 and 2752 mu A mM-1 cm-2 in two linear ranges, 0.5-2.5 mM and 2.5-8.5 mM, respectively with a detection limit of 0.012 +/- 0.0014 mM. The performance of the sensor was validated by estimating lactic acid in human serum and the sweat generated through physical exercise. The estimated lactic acid concentrations are in good agreement with clinical analysis data. This indicates the potential applicability of the sensor in the point-of-care detection of lactic acid. This work reports the electrochemical sensing of lactic acid on a gold microflower-modified screen-printed carbon electrode in a neutral medium. The electrochemical reduction of the lactic acid to lactaldehyde is utilized for sensing, which is novel. The developed sensor is highly selective and sensitive towards lactic acid and its performance is validated in blood serum and sweat. image