Oxygen Detection in Dermal Interstitial Fluid with Microneedles Based on Platinum Nanoparticles

Area of Science:

• Biomedical Engineering
• Sensor Technology
• Nanomaterials

Background:

• Real-time monitoring of dermal interstitial fluid (ISF) oxygen levels is crucial for understanding physiological states and diagnosing conditions.
• Existing methods for oxygen sensing are often invasive, cumbersome, or lack the sensitivity and responsiveness required for continuous monitoring.
• Microneedle technology offers a minimally invasive approach for accessing ISF, but its application in oxygen sensing requires novel material development and integration.

Purpose of the Study:

• To develop and evaluate a microneedle-based oxygen sensor wearable patch (O2 MN) for real-time, minimally invasive detection of dermal ISF oxygen.
• To pioneer the use of platinum nanoparticles as the sensing element in a microneedle platform for enhanced electrochemical sensitivity.
• To comprehensively assess the performance of the O2 MN sensor through in vitro, on-body, and in vivo experiments.

Main Methods:

• Fabrication of a wearable patch integrating a microneedle working electrode with platinum nanoparticles and a microneedle counter/reference electrode (Ag/AgCl ink).
• Electrochemical characterization of the O2 MN sensor, including sensitivity, response time, reversibility, repeatability, stability, and reproducibility.
• Validation of sensor accuracy through in vitro tests, on-body measurements in euthanized rats, and in vivo correlation studies with blood oxygen levels.

Main Results:

• The O2 MN sensor demonstrated high sensitivity (-0.51 nA μM-1) and a rapid response time (9 s) for detecting oxygen in the range of 10-254 μM at -0.3 V.
• Excellent analytical performance was observed, including high reversibility (RSD = 3.4%), repeatability (RSD = 5.2%), medium-term stability (1.9% deviation over 90 min), and acceptable reproducibility (6.6%).
• In vitro validation showed a Pearson correlation coefficient of 0.99, and in vivo studies revealed a strong positive correlation (Pearson correlation coefficient = 0.83) between dermal ISF and blood oxygen levels.

Conclusions:

• The developed microneedle-based oxygen sensor wearable patch (O2 MN) is a reliable and effective tool for real-time, minimally invasive monitoring of dermal ISF oxygen.
• The use of platinum nanoparticles in the microneedle platform provides high electrochemical sensitivity and rapid response, outperforming previous oxygen sensing technologies.
• The O2 MN patch holds significant potential for diverse biomedical applications, enabling continuous physiological monitoring and improved diagnostic capabilities.