Reusable gold nanoparticle enhanced QCM immunosensor for detecting C-reactive protein

This report describes a novel method to realize high sensitive C-reactive protein (hs-CRP) by using a quartz crystal microbalance (QCM) immunosensor based on 20 nm gold nanoparticles conjugated anti-CRP antibodies. A sandwich-type assay was established: CRP was firstly recognized by the anti-CRP antibody which was immobilized on the gold electrode of the QCM and the sensitivity was enhanced further by binding AuNP conjugated anti-CRP antibody secondly. The response of the QCM is observed to be linearly relative to the CRP concentration in the range of 20 ng/mL to 30 μg/mL and the detection limit is enhanced to a great extend by the amplification procedure. The sensor was regenerated online by the solution of 3 mol/L Urea while preserving the activity of the immunosensor.