In-situ monitoring of cellular H 2 O 2 within 3D cell clusters using conductive scaffolds

Accurately monitoring H O concentrations in 3D cell clusters is challenging due to limited diffusion and rapid degradation of H O in the culture medium. Despite the incorporation of three-dimensional cell culture approaches, the detection technology has largely remained as a 2D planar system. In this study, we present a versatile approach of 3D electrochemical sensing utilizing carbon nanotubes as conductive scaffolds for in-situ monitoring of H O in cell clusters. These scaffolds enabled direct contact between H O released from cells and the electrodes, thereby improving sensitivity and ensuring biocompatibility for cell aggregates. The scaffolds exhibited electrocatalytic behavior with a limit of detection of 6.7 nM H O . Additionally, the electrochemical responses of cell clusters with the scaffolds exhibited significantly higher current compared to clusters without scaffolds when stimulated with model drugs. This study underscores the potential of conductive scaffolds for real-time monitoring of H O released from cell clusters in 3D microenvironments.