An interleukin-6 ZnO/SiO2/Si surface acoustic wave biosensor

A novel high sensitivity ZnO/SiO2/Si Love mode surface acoustic wave (SAW) biosensor for the detection of interleukin-6 (IL-6), is reported. The biosensors operating at 747.7 MHz and 1.586 GHz were functionalized by immobilizing the monoclonal IL-6 antibody onto the ZnO biosensor surface both through direct surface adsorption and through covalent binding on gluteraldehyde. The morphology of the IL-6 antibody-protein complex was studied using scanning electron microscopy (SEM), and the mass of the IL-6 protein immobilized on the surface was measured from the frequency shift of the SAW resonator biosensor. The biosensor was shown to have extended linearity, which was observed to improve with higher sensor frequency and for IL-6 immobilization through the monoclonal antibody. Preliminary results of biosensor measurements of low levels of IL-6 in normal human serum are reported. The biosensor can be fully integrated with CMOS Si chips and developed as a portable real time detection system for the interleukin family of proteins in human serum.