In this study, we analyze the relations between radiation properties and sensitivity of optical nanoantennas and their shape and design parameters using nanocircuit concepts. We apply these findings to optimize the sensitivity and bandwidth of printed plasmonic nanoantennas for their potential use in optical communications and label-free biosensing applications. In comparison to conventional plasmonic optical sensors, which mainly rely on localized surface plasmons, our design rules suggest that optical nanoantennas may provide enhanced sensitivity for biomedical applications, and our analytical solutions based on their equivalent nanocircuit model may provide an efficient tool for their design optimization. Several numerical simulations are presented to verify utility of this design method, providing excellent agreement between numerical and analytical results.