Continuous Measurement of Lactate Concentration in Human Subjects through Direct Electron Transfer from Enzymes to Microneedle Electrodes

• Published in: ACS sensors Vol. 8; no. 4; pp. 1639 - 1647
• Main Authors: Freeman, David M. E., Ming, Damien K., Wilson, Richard, Herzog, Peter L., Schulz, Christopher, Felice, Alfons K. G., Chen, Yu-Chih, O’Hare, Danny, Holmes, Alison H., Cass, Anthony E. G.
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 28.04.2023
• Subjects: Electrodes; Electron Transport; Electrons; Humans; Lactic Acid; Research Subjects; microneedles; continuous monitoring; biosensor; lactate; direct electron transfer enzyme; in-human study
• ISSN: 2379-3694; 2379-3694
• DOI: 10.1021/acssensors.2c02780

Microneedle lactate sensors may be used to continuously measure lactate concentration in the interstitial fluid in a minimally invasive and pain-free manner. First- and second-generation enzymatic sensors produce a redox-active product that is electrochemically sensed at the electrode surface. Direct electron transfer enzymes produce electrons directly as the product of enzymatic action; in this study, a direct electron transfer enzyme specific to lactate has been immobilized onto a microneedle surface to create lactate-sensing devices that function at low applied voltages (0.2 V). These devices have been validated in a small study of human volunteers; lactate concentrations were raised and lowered through physical exercise and subsequent rest. Lactazyme microneedle devices show good agreement with concurrently obtained and analyzed serum lactate levels.