In this paper, a complete study is carried out investigating the relationship between the biosensing and the electrical characteristics of freestanding two-terminal Schottky-barrier silicon nanowires. This paper successfully reproduces computationally the electrical behavior obtained experimentally from the nanowire devices before and after the surface biomodification. Throughout modeling and simulations, this paper confirms that the experimental results obtained from the electrical characterization of bare two-terminal Schottky-barrier silicon nanowires present current-to-voltage characteristics fully equivalent to that of a pure memristor device, according to the literature. Furthermore, this paper shows that the voltage gap appearing in the current-to-voltage characteristics for nanowires with biomodified surface is related to capacitive effects due to minority carriers in the nanowire and it is also indicated that those effects are strongly affected by the concentration of antigens uptaken on the device surface. Overall, this paper confirms the implication of the memristive effect for biosensing applications and therefore, demonstrates the memristive biosensors.