Biosensors are analytical tools that play an important role in advanced applications, especially in the
monitoring of biological molecules related to health conditions. A variety of biosensors have been described in this
review to emphasize the important applications in the biological field. These biosensors are categorized into four
groups depending on the bioreceptor molecules, including enzymatic biosensors, immuno-based biosensors, DNA-based
biosensors, and other interesting biosensors. Many platforms and materials have been developed with various benefits.
The detection principles of the biosensors in this review are focused on optical and electrochemical techniques due to
their characteristic advantages. Information of using novel materials for fabrication of biosensors is also provided.