Ultrahigh-sensitive wireless QCM with bio-nanocapsules

Quartz-crystal-microbalance (QCM) biosensor is a mass-sensitive biosensor, and its sensitivity in detecting target proteins can be improved with weighted detection antibodies. In this communication, we propose a mass-amplified detection of biomarkers by bio-nanocapsules (BNCs) in wireless high-frequency multichannel QCM biosensor. BNC exhibits molecular mass of 6.57 MDa and possesses many immunoglobulin-G (IgG) Fc-binding Z domains on its surface, making it possible to display ∼60 antibodies in an oriented immobilization manner. We find that by reinforcing the bond strength between the Z domain and the Fc part of antibody with the cross-linker, a high sensitive detection of biomarkers with QCM is realized. We used multichanel wireless QCM system with fundamental resonance frequencies above 54 MHz and performed detection of C-reactive protein. The detection limit is lower than 10 pg/mL, confirming that combination of BNC and wireless high-frequency QCM allows high sensitivity detection of biomarkers.