Colorimetric biosensors for pathogen detection toward accessible and scalable diagnostics

Colorimetric biosensors are emerging as versatile analytical platforms for healthcare, environmental monitoring, and food safety by converting biological interactions into visible signals for rapid, cost-effective detection. Advances in nanobiotechnology and materials science, including inorganic nanoparticles, metal-organic frameworks, and quantum dots, have enhanced sensitivity through signal amplification and tunable optical properties. Integration with microfluidics, smartphone-based imaging, machine learning, and Internet of Things platforms has enabled portable, real-time diagnostics. Emerging wearable and multiplexed formats further expand accessibility and sustainability. However, challenges remain in ensuring stability, selectivity in complex matrices, reproducibility, and large-scale manufacturing for widespread deployment. This perspective highlights emerging directions in nanobiotechnology-driven colorimetric biosensors, exemplified by coronavirus disease 2019 (COVID-19) detection platforms developed during the global severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. Rather than cataloging sensing chemistries alone, this perspective advances a translational roadmap that connects physical sensing principles, nanobiotechnology advances, and digital integration strategies to enable scalable, field-deployable diagnostic platforms.