The Role of the Biofunctionalized Silica Nanospring Surface for Selective Biosensing

We have addressed the challenges by integrating an immunoassay technique, which is one of the most powerful techniques because of the specificity and selectivity of antigen-antibody interaction, into a biosensor constructed with vertically-aligned (silica) nanosprings (VANS). The unique characteristics of VANS, such as biocompability, large surface-to-volume ratio, etc., facilitate selective sensing and miniaturization. Silane chemistry is used to functionalize VANS surfaces to covalently link a probe layer onto the VANS, providing better control over the concentration and orientation of the attached biomolecule. A mouse immunoglobulin G (IgG), which is sandwiched in between two layers of a goat antimouseIgG, binds the goat antimouseIgG, and is detected by the changes in the impedance of the biosensor. The selectivity of the sensor has been verified using rabbit IgG as a control. The experiments reveal that the response of the VANS sensor is solely due to the interaction of the target molecule, i.e . mouse IgG, with the probe layer, i.e . goat antimouseIgG (GαM IgG). The change in impedance indicates that the addition of antibodies impedes ionic motion, thereby changing the effective dielectric response of the VANS-biomolecular medium.