Hydrophobin HGFI–based fibre-optic biosensor for detection of antigen–antibody interaction

A compact S-tapered fibre biosensor functionalised with class I hydrophobin HGFI found in Grifola frondosa has been proposed for the first time to accrue label-free detection of reaction between goat–anti-rabbit immunoglobulin G (IgG) (GAR, antibody) and rabbit–anti-hemagglutinin IgG (R, antigen). The HGFI nanolayer self-assembled on fibre surface provides a distinguished analytical platform to implement biocompatible binding owing to its prominent amphiphilicity and remarkable optical as well as biochemical properties. Water contact angle measurements, atomic force microscopy, and immunofluorescence assay are utilised to characterize the modification properties of siliconised substrate surface with HGFI. Functionalisation of the S-tapered fibre is achieved by exploiting self-assembly of HGFI and immobilisation of GAR for specific R detection. HGFI with a concentration of 300 μg/ml allows the formation of a self-assembled amphipathic film on fibre surface, which can adsorb antibody smoothly with such desirable merits as ease of operation, fast response, good stability, good repeatability, and no side effects. Immunoassay experiments are conducted based on dip wavelengths interrogation of the interferometric transmission spectrum. In this study, we propose a novel antigen detection scheme, which could be extended for the detection of other biomolecules owing to its high integration, good specificity, real-time detection, and simple detection scheme.