RESUMO
A surface plasmon resonance (SPR) based immunosensor is presented for highly sensitive and selective detection of 17ß-estradiol by the indirect competitive inhibition immuno assay, employing anti-17 ß-estradiol antibody as high molecular weight (HMW) interactant. Immobilization of estradiol-BSA conjugate onto the nano thin gold surface was accomplished by covalent amide linkage through self assembled monolayer. The proposed biosensor is simple to fabricate, reproducible and exhibit excellent sensitivity for estrogen (detection limit,1 pg mL-1) without any significant interference from structurally similar steroidal hormone, progesterone and non-steroidal compound bisphenol-A. The proposed surface displayed a high level of stability during repeated regeneration and immunoreaction cycles suitable for biosensor development.
Assuntos
Anticorpos/imunologia , Técnicas Biossensoriais/métodos , Estradiol/análise , Ressonância de Plasmônio de Superfície/métodos , Anticorpos/química , Técnicas Biossensoriais/instrumentação , Estradiol/imunologia , Técnica Indireta de Fluorescência para Anticorpo/instrumentação , Técnica Indireta de Fluorescência para Anticorpo/métodos , Fluorimunoensaio/instrumentação , Fluorimunoensaio/métodos , Ouro/química , Nanopartículas Metálicas/química , Peso Molecular , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Ressonância de Plasmônio de Superfície/instrumentaçãoRESUMO
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.
