Fig 1.
Optical biosensor based on SPR in a POF and experimental setup.
Scheme of synthesis of derivatized SAM on chip POF. The gold surface was treated sequentially with a solution of α-lipoic acid (a), ethylenediamine (b) and butyric acid (c).
Fig 2.
3D rendering of: a gold coated Si substrate a) before and b) after functionalization with lipoic acid, and c) after additional subsequent functionalization with butyric acid and pOBP. Note that a different Z scale was used for the three images.
Fig 3.
Porcine Odorant Binding Protein structure.
Cartoon representation of the structure pOBP with butanal. The image was produced by Protein workshop Right.
Fig 4.
Binding experiment-SPR results.
(a) SPR transmission spectra, normalized to the air spectrum, for different pOBP concentrations in the case of sensor with gold layer with bio-receptor. Inset: Zoom of the resonance wavelengths region. (b) Resonance wavelength variation as a function of pOBP concentrations [μM].
Fig 5.
Control—SPR experimental results.
SPR transmission spectra, normalized to the air spectrum, for different pOBP concentrations in the case of the reference sensor with gold layer—SAM without bio-receptor. Inset: Zoom of the resonance wavelengths region.
Fig 6.
(a) SPR transmission spectra, normalized to the air spectrum, for different concentration in solution of butanal and with a fixed concentrations of pOBP (1.27 μM), in the case of sensor with gold layer with bio-receptor. Inset: Zoom of the resonance wavelengths region. (b) Resonance wavelength variation as a function of butanal concentration, obtained with binding of a fixed concentration of pOBP in presence of increasing concentration of butanal during pre-incubation time.