Label-free detection of c-reactive protein using zno tetrapods modified quartz crystal microbalance system

A label free c-reactive protein (CRP) biosensor based on anti-CRP immobilized on ZnO tetrapods was studied by quartz crystal microbalance (QCM). The ZnO tetrapods were synthesized by evaporating high purity zinc pellets (99.999%) at 900 °C in a high temperature furnace and then distributed onto the electrode surfaces of QCM at room temperature. The monoclonal anti-C-reactive protein was immobilized on ZnO tetrapods film after 3-aminopropyltrietoxy silane and glutaraldehyde modified. The stability of immobilized anti-CRP was studied and the result showed anti-CRP strongly immobilized on ZnO tetrapods after modifying. The antibody immobilized ZnO tetrapods based QCM sensor electrode detected the concentration range of CRP from 0.1 μg/mL to 26 μg/mL with an acceptable sensitivity of 7±0.17 Hz/decade. The response of CRP sensor has high linearity (0.99) and stable for above detected concentrations. The time response of antibody immobilized ZnO tetrapods based sensor was observed less than 10 s with good selectivity, reproducibility, repeatability and stability. All the results indicated that one-dimensional ZnO structure is a good material for biosensor application.