A Soft and Stretchable Platinum Nano Particle Based Electrode for Real-Time In Vivo Monitoring of Hydrogen Peroxide

Hydrogen peroxide (H2O2) plays a crucial role as a signaling molecule in tissue environments, influencing oxidative stress responses, immune functions, and cellular signaling pathways. Real-time monitoring of H2O2 levels within tissues is essential for understanding oxidative dynamics implicated in diseases such as neurodegenerative disorders, cardiovascular diseases, and cancer. For example, in neurological studies, monitoring H2O2 provides insights into oxidative damage mechanisms in brain tissues, enhancing our understanding of diseases like Alzheimer's and Parkinson's. Similarly, in cardiovascular contexts, real-time H2O2 monitoring helps assess oxidative stress levels in vascular tissues, crucial for managing inflammation and promoting cardiovascular health. Additionally, in oncology, monitoring H2O2 in tumor microenvironments aids in understanding tumor progression and responses to therapies.<br/><br/>Here, we have developed a soft and stretchable platinum-nanoparticle (PtNP)-based electrode for in-vivo H2O2 monitoring. The sensor employs a multi-layered architecture, featuring a brittle interfacial platinum-nanoparticle-based layer electrically connected to an underlying stretchable conductive layer through a vertically conductive film. The sensor's silicone-based conductive stretchable trace is sealed with a silicone-based vertically conductive layer. The interfacial layer is fabricated through e-beam deposition of Cr/Au, followed by PtNP electrodeposition. Even under strain and fracturing of the PtNP layer, the fractured surfaces remain electrically connected to the bottom stretchable traces, thereby preserving the sensing capability unaltered under 100% strain.<br/><br/>To assess its robustness for in vivo applications, the stretchable H2O2 sensor can be tested across various biological systems, including human stem cell-derived neurons and cardiomyocytes, primary neurons and astrocytes, and ex vivo and in vivo mouse brain models. Implanted in the brains of mice, the sensor adheres smoothly to brain tissues, providing stable, real-time recordings of H2O2 dynamics in response to pharmacological stimuli and pathological conditions. Future enhancements will integrate wireless modules for unrestricted movement measurements, further advancing its utility in studying and treating oxidative stress-related diseases.