Label-Free Optical Recording of Bioelectrical Signals Harnessing Bio-electrochromic Materials Interface.

Understanding how a network of neurons receive, store and process information in the human brain is a grand scientific challenge of our time. Neurons encode and communicate information through electrical signals. Traditional electrode-based recording methods such as patch clamp or multielectrode arrays are either highly invasive to cells or inflexible to sense electrical fields of cells at user-selected spatial positions with limited recording capacity. Existing optical methods, on the other hand, rely heavily on inserting voltage-sensitive fluorescent molecules into the cell membrane, which suffer from cell phototoxicity, limited recording duration and signal-to-noise ratio due to photobleaching.<br/><br/>Here, we introduce ElectroChromic Optical REcording (ECORE), a new electrophysiology method that optically reads out the electrical activity of electrogenic cells in a label-free and non-perturbative manner harnessing the unique properties of electrochromic polymers. The ECORE method fundamentally differs from any existing voltage recording approaches in that cell electrical signals are read out optically through voltage-sensitive optical absorption of electrochromic polymer thin films. Changes in optical reflection of the film, rather than fluorescence, are detected to probe cell electrical activities through a home-engineered optical system with a high signal-to-noise ratio. In this way, ECORE does not perturb the physiology of cells without the insertion of any molecular probes. It is also not limited by photobleaching or phototoxicity, making it a suitable tool for long-term recording of cell electrical signals over weeks or months. I will talk about single-color, dual-color, and multi-channel optical recording of electrical signals from heart muscle cells, heart tissue, neurons, and brain slices interfaced with different conjugated electrochromic polymers with high sensitivity and throughput.