Mass spectrometric detection of the amino acid sequence polymorphism of the hepatitis C virus antigen.

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.

[SOI-nanowire biosensor for the detection of D-NFAT 1 protein].

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.