Molecularly imprinted polypyrrole films for smart voltage-gated molecular uptake and release

The controlled uptake and release of biochemical molecules at material interfaces is critical for applications in drug delivery, biosensing, and neurostimulation. While molecularly imprinted polymers (MIPs) offer selective molecular recognition, real-time visualization of electrically controlled molecular trafficking remains underexplored. This study investigates a voltage-gated molecular interface using molecularly imprinted polypyrrole (MIP-PPy) films, designed to enable reversible uptake and release of target molecules with direct optical monitoring. Fluorescein sodium salt, a model for anionic neurotransmitters, was incorporated during electrochemical polymerization to create specific recognition sites within the polymer matrix. We employed real-time fluorescence microscopy to directly track molecule transport dynamics in response to applied voltages, utilizing a custom 3D-printed flow cell for simultaneous electrical control and in situ imaging. The MIP-PPy films demonstrated self-regenerating uptake behavior from the surrounding solution, overcoming the limitations of unidirectional release in conventional microfluidic systems. This bidirectional control introduces new opportunities for reservoir-free, adaptive chemical modulation. Biocompatibility assessments using SH-SY5Y neuroblastoma and Huh7 hepatoma cells demonstrate high levels of viability and adhesion, confirming the films' suitability for biological integration. Overall, this study provides a visual and quantitative platform for investigating electrically induced molecular transport, which will assist in the development of closed-loop drug delivery and neurostimulation systems inspired by synaptic signaling.