Specific detection of proteins using nanomechanical resonators

Rapid, sensitive and inexpensive analysis of biological molecules is vital to many fundamental problems in molecular biology. Nanomechanical resonators are of great interest for such applications. The use of these devices for the analysis of protein mixtures would however require the immobilization of probes onto their surfaces in order to enable the specificity of the detection. Such nanoresonator-based specific detection of proteins is here reported using streptavidin as target system, and immobilized biotin as probe. Nanomechanical resonators resistant to stiction were first realized from silicon carbonitride using a novel fabrication method. Vapor-phase deposition of mercaptopropyl trimethoxysilane was performed, and an added mass of 2.22 ± 0.07 fg/μm2 was measured. This linker molecule was used to attach biotin onto the devices, enabling the specific detection of streptavidin. A mass of 3.6 fg/μm2 was attributed to the added streptavidin, corresponding to one molecule per 27 nm2. The specificity of this recognition was confirmed by exposing the devices to a solution of streptavidin that was already saturated with biotin. An additional negative control was also performed by also exposing bare devices to streptavidin in absence of the attached biotin. No resonance frequency shift was observed in either case, confirming the specificity of the detection.