A SERS-active microneedle array for rapid and minimally invasive lactic acid detection.

Area of Science:

• Biomedical Engineering
• Sports Science
• Analytical Chemistry

Background:

• Intense exercise leads to lactic acid (LA) accumulation, causing muscle fatigue and impacting physiological functions.
• Lactate threshold (LT) is crucial for athletic performance, making LA detection vital for assessing physical condition and optimizing training.
• Current methods for LA detection can be invasive or lack sensitivity, necessitating advanced monitoring tools.

Purpose of the Study:

• To develop and validate a surface-enhanced Raman scattering (SERS)-active microneedle (MN) array for real-time LA detection in interstitial fluid.
• To investigate the impact of physiological state (fasting vs. normal feeding) and exercise intensity on LA accumulation.
• To assess the potential of SERS-MN arrays for guiding exercise training and rehabilitation.

Main Methods:

• Fabrication of SERS-active microneedle arrays by integrating gold nanoshells, 4-mercaptobenzeneboronic acid, and lactate oxidase.
• Insertion of MN arrays into the skin of mice to detect LA in the interstitial fluid (ISF).
• Monitoring changes in ISF LA concentration in mice under different exercise durations and feeding conditions.

Main Results:

• The SERS-MN array successfully detected changes in LA concentration in mouse ISF following exercise.
• Normal mice showed significant increases in ISF LA after 3 and 6 minutes of swimming.
• Fasting mice exhibited altered baseline LA levels and a different accumulation rate during exercise compared to normally fed mice.

Conclusions:

• This study presents the first identification of distinct LA production patterns between fasting and normally fed animals.
• Fasting influences baseline LA levels and exercise-induced LA accumulation rates.
• The developed SERS-MN array shows promise as a safer and more effective tool for exercise monitoring and personalized training guidance.