A silicon nanosensor technology based on electrical impedance measurements has been developed for the detection of proteins. The nanosensor miniaturizes the high-density, low-volume multiwell plate concept. The scientific core of this technology lies in integrating nanoporous membranes with microfabricated chip platforms. This results in the conversion of individual pores into nanowells of picoliter volume. Monoclonal antibodies were localized and isolated into individual wells. Detection of two cardiac proteomic biomarkers has been demonstrated with this technology. The two proteins, C-reactive protein and NT-pro–brain natriuretic peptide (BNP), are associated with adverse cardiac outcomes in clinical samples when detected in the pg/mL concentration. The formation of the antibody-antigen binding complex occurs in individual wells. The membrane allows for robust separation among individual wells. This technology has the capability to achieve near real-time detection with improved sensitivity at 1 ag/mL for BNP and 1 fg/mL for CRP from human serum.