Natural pigment-based biosensors for environmental monitoring.

The relentless acceleration of human activities, combined with increasing global consumption patterns, has resulted in the widespread release of various pollutants into the biosphere, posing significant risks to both ecosystems and human health. Traditional analytical methods for monitoring these environmental threats often depend on complex, energy-intensive instruments or toxic synthetic reagents, which inadvertently contribute to the chemical waste cycle. In response to the urgent need for greener analytical approaches, natural pigments have emerged as a highly promising, eco-friendly alternative to synthetic indicators. This review critically summarizes recent advances in the development of natural pigment-based biosensors for environmental sensing. It systematically explores recent examples of detecting heavy metals, gases, pH, and pathogen genes. The review also discusses whole-cell biosensors, in which the pollutant reacts with the pigment or with a genetic pathway that leads to pigment production, resulting in a color change. By integrating biodegradable and non-toxic natural pigments with affordable and user-friendly sensing technologies, this work highlights the next generation of a truly sustainable framework for real-time pollution surveillance.