Bacteriorhodopsin-Based pH Sensor for Cell Culture Condition Regulation.

In cell culture research and biotechnology, precise pH monitoring is crucial for maintaining cellular health and ensuring reliable experimental outcomes. Traditional pH measurement methods, such as glass electrodes and chemical indicators, are often limited by issues such as fragility, calibration requirements, and potential cytotoxicity. This study presents a novel pH sensor based on bacteriorhodopsin (bR), a light-sensitive protein that undergoes conformational changes in response to pH fluctuations, generating a measurable photoelectric signal. The integrated bR-based electrochemical electrode in a flexible pH biosensor is demonstrated, with measurements spanning the physiological pH range of 6.0-8.5. The sensor shows a high correlation (R2 = 0.977) between photo-generated current signals and pH, indicating robust performance for real-time, non-invasive pH monitoring. The biocompatibility and non-invasive nature of this sensor make it particularly suitable for continuous monitoring in cell culture environments. The sensor's practical application is validated by its integration into cell well plates for tracking the pH changes during cell growth, providing valuable insights into metabolic processes and growth conditions. In the future, efforts will focus on enhancing sensor sensitivity, stability, and integration with multi-parameter monitoring systems for more comprehensive cell culture analysis.