21. Electrochemical Biosensors

Semiconductors made from group 12 and 16 elements are referred to as group II–VI semiconductors. These include group 12 elements such as cadmium and zinc and group 16 elements, called chalcogens, such as sulfur, selenium, and telluride. Combination of these elements results in various core–shell structures such as cadmium selenide, cadmium sulfide, cadmium telluride, and various zinc-based chalcogens. These elements have low band gap and have high optical activity. As a result, these materials have been largely explored for the development of optical-based biosensors, especially fluorescent and chemiluminescent based.

Other than optical activity, these materials exhibit good electrochemical properties as well due to their low band gap but still these core–shell materials have been less exploited for utilizing their electrochemical properties for applications like electrochemical biosensing. Electrochemical (bio)sensors have been the driving force for researchers since long due to their robustness, miniaturization possibility, and simplicity in fabrication and usage. These are widely employed for number of applications like food quality, water quality, and point-of-care devices for biomedical domain. This chapter is intended to give an overview of the various group II–VI semiconductors, their functionalization methods, and newly explored electrochemical-based biosensing applications.