The technology is a novel red blood cell (RBC) based biosensor capable of detecting molecules in the blood for diagnostic purposes, as well as, delivering therapies directly to blood cells within the body. This technology utilizes an innovative method of mimicking RBCs for use as a biosensor via a multi-layer coating consisting of poly-L-lysine and a red blood cell membrane. Proof-of-concept has been achieved, as the inventors have successfully attached nanoparticles to their biosensor and deposited the nanoparticles in an in vitro assay.