A novel porous silicon based optical Fabry-Perot cavity structure is prepared as a label-free immunosensor platform for detecting antigen-antibody.The lagurus zona pelluciad 3(LZP3) and the specificity of the polyclonal anti-LZP3 antibodies are employed in our laboratory as the target and the probe,respectively.Firstly,the antibodies are immobilized to the porous silicon optical cavity using silanization and glutaraldehyde(GA) chemistry.And then,after the antigen-antibody reaction,it is monitored that the red shift of the reflection spectrum of the immunosensor increases with the antigen concentration.This research also plays a potential role for the extensive applications in immunoassay.
Optical and electrical properties of composites formed by mixing porous silicon （PS） and poly （9, 9- diocty-2, 7-fluorene- co-4, 4＇-butoxydiphenyl） （PFP） have been studied by Fourier transform-infrared spectroscopy （FT-IR）, scanning electron microscopy （SEM） and photoluminescence （PL） spectroscopy. The optical spectra show that porous silicon is incorporated into the polymer without significant change in the polymer properties. The FT-IR spectroscopy has detected the existence of specific interactions, which may be attributed to non-conjugated alkoxy segment. By fitting the current-voltage （/-V） curve of PFP/PS structure with the modified standard ecluation, the n factor and I0 are cletermined
The enhanced sensitivity of a guided mode biosensor is analyzed by employing double-layered porous silicon grating structures. The grating-coupled waveguide structure consists of two porous silicon grating layers with different refractive indices. simulations are carried out by changing the refractive index, which is due to the binding of biological molecules on the porous silicon pore can increase the refractive index of porous silicon. The numerical results show that this novel guided mode biosensor with a double-layered grating can provide not only a very high sensitivity but also a better reflectivity characteristic.
In this paper, we produce porous silicon （PSi） by electrochemical etching, and it is the first time to evaluate the performance of label-free porous silicon biosensor for detection of variable domain of heavy chain of heavy-chain antibody （VHH）. The binding of hen egg white lysozyme （HEWL） and VHH causes a red shift in the reflection spectrum of the biosensor. The red shift is proportional to the VHH concenlration in the range from 14 gg.ml-I to 30 pg.ml~ with a detection limit of 0.648 ng.ml~. The research is useful for the development of label-free biosensor applied in the rapid and sensitive determination of small molecules.
The single-layer porous silicon is prepared by electrochemistry etching method,which is used as an immunosensor for determining recombinant mouse zona pellucida 3 fusion protein(r-mZP3) by Raman spectroscopy analysis at room temperature.The molecule binding increases the effective optical thickness(EOT),and thus the Raman spectrum intensity decreases.The concentration and variation of Raman intensity show a good linear quantitative relation.The excellent sensing performance could open the way to a new family of optical sensors for biological standardization.
Porous silicon （PS） suitable for optical detection of immunoreaction is fabricated. The structure of immunosensor is prepared by the following steps： oxidization, silanization, glutaraldehyde cross-linker, and covalent binding of antibody. When antigen is added into the immunosensor, the Raman intensity is estimated to be linearly reduced according to the concentration of the surface protective antigen protein A （spaA） of below 4.0 μg ml-1. The ultimate detection limit is 1.412 × 102 pg ml-1. Controlled experiments are also presented with non-immune antigen of the spaA, and results show that the immunosensor has high specificity. Compared with the conventional enzyme-linked immuno sorbent assay （ELISA）, this method is quick, inexpensive, and label-free.
