P5 - Optical Immune Biosensors Based on the Nanostructured Silicon and Intended for the Diagnostics of Retroviral Bovine Leucosis

SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Proceedings OPTO 2011
OP - Poster Session
N. Starodub, J. Sitnik - National University of Life and Environmental Sciences, Kyiv (Ukraine), M. Mel‘nichenko - Taras Shevchenko Kiev National University, Kyiv (Ukraine), O. Shmyryeva - National Technical University, Kyiv (Ukraine)
127 - 132


We used the boron doped single-crystal silicon with the square wafers about 0.3 mm of thickness and with the resistance of 1 Ohm*cm. sNPS layers were prepared by the chemical way and their thickness were changed from 3 up to 60 nm. The parameters of the technological process at the chemical modification of the single-crystal silicon surface were controlled by the scanning electronic microscopy (SEM) and the chemical content – Auger electronic spectroscopy. Contacts were formed by the magnetron sputtering of In iones with the use of a metal mask. At the formation of the immune complex (retrovirus proteins – specific antibodies – Ab) in case of the illumination It was stated that the photosensitivity of the structures nano-porous silicon (sPNS) is a little decreased after the immobilization of antigen (Ag -crude sample of the retroviral proteins) but at the addition of Ab (serum blood of ill cows) in the dilution of 1:5000 and, particular, in 1:1000 it sharply is decreased. Unfortunately at the less level of blood dilution (from 1:100 to 1:1) the photosensitivity starts to decrease up to initial level. Maybe, it connected with the increasing of the density of the solution to be analyzed or with other mechanism of the electronic exchanges between the immune complex and the sNPS surface. The deposition of the retroviral proteins on the sNPS a few increases the photoluminescence (PhL) level but at the formation of the specific immune complex it decreases. Moreover, the level of the PhL decreasing depends on the concentration of the specific Ab in the blood. If we used the non-specific Ab or the serum bovine albumin as Ag the level of the PhL does not change. According to our opinion the red PhL may be connected with the tunnel mechanism of the recombination of the charge bearers at the excitation of them in the nano-crystallites of oxide or interface. We do not exclude the hydrogen role too for the generation of the PhL extinguishing. These conclusions are as result of the coincidence of the possible reasons for the PhL decreasing in case of the immune complex formation no the sNPS surface.
To them belong: a) the changes of the absorbance in the solution at the formation of the specific immune complex on the sNPS surface, b) the effect of the immune components or their interaction on the recombinant process of the photocurrent charge in the sNPS. As it is very known the light absorption in the wavelength of the excitation (l = 350 нм) and in the wide field of the sNPS PhL is absent in the Ab and Ag solutions as well as in their complexes.