In this study, we demonstrated that the fiber-optic biosensor based on localized surface plasmon coupled fluorescence (LSPCF) is capable of detecting alpha-fetoprotein (AFP) in human serum. The sensitivity of LSPCF fiber-optic biosensor is not only enhanced but also the specific selectivity is improved since the fluorophores are excited by the localized surface plasmon with high efficiency. Experimentally, this fiber-optic biosensor is able to detect AFP concentration in phosphate buffered saline (PBS) solution from 0.1 ng/mL to 100 ng/mL whereas the linear relationship between the AFP concentrations and the fluorescence signals is shown. Furthermore, a linear response between the fluorescence signals and the concentrations of AFP in human serum from 2.33 ng/mL to 143.74 ng/mL is also obtained. As a result, the detection limit of the LSPCF fiber-optic biosensor on AFP detection is comparable with the conventional enzyme-linked immunosorbent assay (ELISA). Additionally, the LSPCF fiber-optic biosensor benefits on inexpensive, disposable and simpler optical geometry that can become a high efficient immunoassay comparable with the conventional ELISA and radioimmunoassay (RIA) clinically. (C) 2008 Elsevier B.V. All rights reserved.
