A reusable piezo-immunosensor with amplified sensitivity for ceruloplasmin based on plasma-polymerized film

A reusable piezoelectric immunosensor with amplified sensitivity has been developed for the detection of ceruloplasmin (CP) in human serum. The quartz crystal microbalance (QCM) was deposited with plasma-polymerized n-butyl amine film with the surface topology further characterized by using atomic force microscopy (AFM). Anti-ceruloplasmin antibody (CP-Ab) was electrostatically adsorbed on the PPF-modified crystal via an oppositely charged polyelectrolyte layer of alginate. It was found that the alginate-mediated immobilization interface could allow for antibodies to be largely immobilized with well-retained immunoactivity. In particular, a simple regeneration process for the sensor produced, i.e. by shifting the pH, can also be realized. Moreover, an optimized assay medium containing polyethylene glycol (PEG) was tested with enhanced immunosensing response (sensitivity). A dynamic concentration range of two orders of magnitude and a detection limit of 0.15 μg ml⁻¹ of CP were observed. Analytical results of clinical samples show that the developed immunoassay is comparable with the enzyme-linked immunosorbent assay (ELISA) method. However, it presents some superior advantages over the traditional sandwich format in that the analyzing performances are direct, rapid and simple without multiple separation and labeling steps.