Methods and devices for detecting a target agent of interest, e.g., a pathogen, in a sample are described herein. In some embodiments, a sensor is provided that can include a substrate, a graphene layer disposed on a surface of said substrate, and a protein bound to said graphene layer. The protein can be capable of binding to one or more target agents of interest, e.g., pathogens, etc. The binding of the protein to the one or more target agents of interest can generate a change in an electrical property of the graphene layer.