In this study, we describe a novel method for analyzing protein-protein binding kinetics at ultra-low concentration
(1 pg/mL) using a localized surface plasmon coupled fluorescence fiber-optic biosensor (LSPCF-FOB). The association
and dissociation rate constants, ka and kd, respectively, for the binding kinetics of the mouse IgG/ anti-mouse IgG
interaction have been calculated to be ka = (5.9928±3.1540)x10<sup>6</sup> M<sup>-1</sup>s<sup>-1</sup> and kd = (1.0587±0.5572)x10<sup>-3</sup> s<sup>-1</sup>. The
theoretical basis of this analytical approach is a rapid-mixing model integrated with a two-compartment model; has been
experimentally verified in this study as well. The LSPCF-FOB provides a potentially alternative option for characterizing
the interaction of biomolecules at ultra-low concentrations.
In order to enhance the sensitivity of conventional rapid test technique for the detection of swine-origin influenza A
(H1N1) viruses (S-OIVs), we used a paired surface plasma waves biosensor (PSPWB) based on SPR in conjunction with an optical heterodyne technique. Experimentally, PSPWB showed a 125-fold improvement at least in the S-OIV detection as compared to conventional enzyme linked immunosorbent assay. Moreover, the detection limit of the PSPWB for the S-OIV detection was enhanced 250-fold in buffer at least in comparison with that of conventional rapid influenza diagnostic test.
This study demonstrates a novel phase-sensitive surface plasman resonance biosensor (PS-SPRB) which is able to
convert the phase modulation into amplitude modulation analytically via a differential amplifier. PS-SPRB is able to
measure biomolecule interactions at ultra-low concentration relying on the properties of phase sensitive detection at
shot-noise detection in a real-time. The common-phase noise-rejection mode is provided in PS-SPRB to be able to
immune the background phase noise efficiently. The experimental results confirm the detection sensitivity of 0.00001 wt
% concentration of sucrose solution and 10 fg/ml mouse IgG interaction with anti IgG in real time.
Alpha-fetoprotein (AFP) detection by using a localized surface plasmon coupled fluorescence (LSPCF) fiber-optic biosensor is setup and experimentally demonstrated. It is based on gold nanoparticle (GNP) and coupled with localized surface plasmon wave on the surface of GNP. In this experiment, the fluorophores are labeled on anti-AFP which are bound to protein A conjugated GNP. Thus, LSPCF is excited with high efficiency in the near field of localized surface plasmon wave. Therefore, not only the sensitivity of LSPCF biosensor is enhanced but also the specific selectivity of AFP is improved. Experimentally, the ability of real time measurement in the range of AFP concentration from 0.1ng/ml to 100ng/ml was detected. To compare with conventional methods such as enzyme-linked immunosorbent assay (ELISA) or radioimmunoassay (RIA), the LSPCF fiber-optic biosensor performs higher or comparable detection sensitivity, respectively.