A method for detection and identification of the hepatitis C virus antigen (HCVcoreAg) in human serum with consideration for possible amino acid substitutions is proposed. The method is based on a combination of biospecific capturing and concentrating of the target protein on the surface of the chip for atomic force microscope (AFM chip) with subsequent protein identification by tandem mass spectrometric (MS/MS) analysis. Biospecific AFM-capturing of viral particles containing HCVcoreAg from serum samples was performed by use of AFM chips with monoclonal antibodies (anti-HCVcore) covalently immobilized on the surface. Biospecific complexes were registered and counted by AFM. Further MS/MS analysis allowed to reliably identify the HCVcoreAg in the complexes formed on the AFM chip surface. Analysis of MS/MS spectra, with the account taken of the possible polymorphisms in the amino acid sequence of the HCVcoreAg, enabled us to increase the number of identified peptides.

The nanowire (NW) detection is one of fast-acting and high-sensitive methods allowing to reveal potentially relevant protein molecules. A NW biosensor based on the silicon-on-insulator (SOI)-structures was used for biospecific label-free detection of NFAT 1 (D-NFAT 1) oncomarker in real time. For this purpose, SOI-nanowires (NWs) were modified with aptamers against NFAT 1 used as molecular probes. It was shown that using this biosensor it is possible to reach the sensitivity of ~10(-15) M. This sensitivity was comparable with that of the NW biosensor with immobilized antibodies used as macromolecular probes. The results demonstrate promising approaches used to form the sensor elements for high-sensitive disease diagnostics.

Change in temperature is one of the factors affecting the activity of enzymes. In this work, the thermal denaturation and aggregation of cytochrome P450 BM3 were studied by atomic force microscopy. The specific temperature transitions were studied by fluorescence analysis. In the low melting temperature range (10–33°C), a decrease in the fluorescence intensity of the aromatic residues was observed simultaneously with an increase in the fluorescence intensity of the flavin groups. The protein melting in this range indicated three narrow S-shaped cooperative transitions at 16, 22, and 29°C. Atomic force microscopy analysis in this temperature range showed that the BM3 molecules retained a globular shape as compact objects (heights, h < 7 nm; lateral dimensions, d < 50 nm), but the protein oligomeric state changed. The first two transitions were accompanied by a decrease in the degree of oligomerization and the third one by its increase.

The nanowire (NW) detection is one of the fast-acting and high-sensitive methods, which can recognize potentially relevant protein molecules. A NW-biosensor based on the silicon-on-insulator (SOI)-structures has been used for biospecific label-free real time detection of the NFATc1 (D-NFATc1) oncomarker. For this purpose, SOI-nanowires (NWs) were modified with aptamers against NFATc1 used as molecular probes. It was shown that using this biosensor it is possible to reach sensitivity of 10−15 M. This sensitivity was comparable to that of the NW-biosensor with immobilized antibodies used as macromolecular probes. The results demonstrate that approaches used in this study are promising for development of sensor elements for high-sensitive diagnostics of diseases.

Atomic force microscopy with two types of probes—standard (radius of curvature R ∼ 10 nm) and supersharp (R ∼ 2 nm)—was used to determine an oligomeric state of CYP102A1. Using the standard probes CYP102A1 images were obtained in liquid, air and vacuum environments, and a CYP102A1 monomer: oligomer ratio α ≈ 1 was also determined. However, the use of standard probes did not allow to resolve structures of these oligomers. Using the supersharp probes it was possible to determine not only the monomer: oligomer ratio, but also to evaluate the dimer: trimer: tetramer ratio in vacuum. Thus, the ratio α for CYP102A1 in liquid can be determined by the standard probes in liquid, air, and vacuum, while oligomeric states of this protein can be specified by using the supersharp probes in vacuum.

The possibility of detection of serological markers, containing the hepatitis B surface antigen (HBsAg) and hepatitis C virus core-antigen (HCVcoreAg) in human serum, by a new atomic force micros-copy (AFM)-based nanotechnological approach has been demonstrated. The antibodies against the hepatitis B virus surface antigen (anti-HBsAg) and the antibodies against the hepatitis C virus core antigen (anti-HCVcoreAg) were immobilized on an AFM-chip. It was shown that such approach enables to detect HBsAg, HCVcoreAg and the viral fragments containing these antigens in the serum. The comparative analysis of detection of HBsAg-and HCVcoreAg-containing particles by the AFM method versus traditional methods (ELISA, PCR) has demonstrated the 75% coincidence of results between the AFM and two other methods.