Surface plasmon resonance based immunosensor for serological diagnosis of dengue virus infection

Surface plasmon resonance (SPR) is a promising tool in sensor technology for biomedical applications. An SPR based immunosensor was established for label free and real time assay for the serological diagnosis of dengue virus infection employing the dengue virus antigen as the sensing element. The dengue virus antigen conjugated with bovine serum albumin is covalently immobilized on a gold sensor chip via activated self-assembled monolayer (SAM) of 11-mercaptoundecanoic acid, by amide coupling. Surface morphology of the biosensor was recorded using atomic force microscopy. Presence of dengue virus specific IgM antibodies in dengue positive sera was monitored by increase in resonance angle in direct immunoassay, whereas the principle of indirect competitive inhibition immunoassay was used to detect presence of dengue virus for early detection of the onset of dengue viral infection in clinical diagnostics. Results were compared with those obtained by MAC-ELISA. The regeneration was achieved by pepsin solution in glycin-HCl buffer (pH 2.2) and sensor surface displayed a high level of stability during repeated immunoreaction cycles. The proposed biosensor being simple, effective and based on utilization of natural antigen-antibody affinity, our study presents an encouraging scope for development of biosensors for diagnosis of dengue and dengue hemorrhagic fever (DHF) which continues to be a major health problem in the tropical and subtropical regions of world.