Registration of the protein with compact disk

Aptamer-Sensitized Nanoribbon Biosensor for Ovarian Cancer Marker Detection in Plasma

The detection of CA 125 protein in buffer solution with a silicon-on-insulator (SOI)-based nanoribbon (NR) biosensor was experimentally demonstrated. In the biosensor, sensor chips, bearing an array of 12 nanoribbons (NRs) with n-type conductance, were employed. In the course of the analysis with the NR biosensor, the target protein was biospecifically captured onto the surface of the NRs, which was sensitized with covalently immobilized aptamers against CA 125. Atomic force microscopy (AFM) and mass spectrometry (MS) were employed in order to confirm the formation of the probe–target complexes on the NR surface. Via AFM and MS, the formation of aptamer–antigen complexes on the surface of SOI substrates with covalently immobilized aptamers against CA 125 was revealed, thus confirming the efficient immobilization of the aptamers onto the SOI surface. The biosensor signal, resulting from the biospecific interaction between CA 125 and the NR-immobilized aptamer probes, was shown to increase with an increase in the target protein concentration. The minimum detectable CA 125 concentration was as low as 1.5 × 10−17 M. Moreover, with the biosensor proposed herein, the detection of CA 125 in the plasma of ovarian cancer patients was demonstrated.

Mass Spectrometric Identification of Proteins Enhanced by the Atomic Force Microscopy Immobilization Surface

An approach to highly-sensitive mass spectrometry detection of proteins after surface-enhanced concentrating has been elaborated. The approach is based on a combination of mass spectrometry and atomic force microscopy to detect target proteins. (1) Background: For this purpose, a technique for preliminary preparation of molecular relief surfaces formed as a result of a chemical or biospecific concentration of proteins from solution was developed and tested on several types of chip surfaces. (2) Methods: mass spectrometric identification of proteins using trailing detectors: ion trap, time of flight, orbital trap, and triple quadrupole. We used the electrospray type of ionization and matrix-assisted laser desorption/ionization. (3) Results: It is shown that when using locally functionalized atomically smooth surfaces, the sensitivity of the mass spectrometric method increases by two orders of magnitude as compared with measurements in solution. Conclusions: It has been demonstrated that the effective concentration of target proteins on specially prepared surfaces increases the concentration sensitivity of mass spectrometric detectors—time-of-flight, ion trap, triple quadrupole, and orbital ion trap in the concentration range from up to 10⁻¹⁵ M.

Covalent Protein Immobilization onto Muscovite Mica Surface with a Photocrosslinker

Muscovite mica with an amino silane-modified surface is commonly used as a substrate in atomic force microscopy (AFM) studies of biological macromolecules. Herein, the efficiency of two different protein immobilization strategies employing either (N-hydroxysuccinimide ester)-based crosslinker (DSP) or benzophenone-based photoactivatable crosslinker (SuccBB) has been compared using AFM and mass spectrometry analysis. Two proteins with different physicochemical properties—human serum albumin (HSA) and horseradish peroxidase enzyme protein (HRP)—have been used as model objects in the study. In the case of HRP, both crosslinkers exhibited high immobilization efficiency—as opposed to the case with HSA, when sufficient capturing efficiency has only been observed with SuccBB photocrosslinker. The results obtained herein can find their application in commonly employed bioanalytical systems and in the development of novel highly sensitive chip-based diagnostic platforms employing immobilized proteins. The obtained data can also be of interest for other research areas in medicine and biotechnology employing immobilized biomolecules.

Immuno-MALDI MS dataset for improved detection of HCVcoreAg in sera

Complicated and large-scale challenge the contemporary biomedical community faces are development of highly-sensitive analytical methods for detection of protein markers associated with development of pathogenic mechanisms [2]. The atomic force microscopy (AFM) method in combination with specific fishing is unique among other analytical protein detection approaches; it allows visualization and counting of single protein molecules [3–6]. The present dataset focus on mass spectrometry method for detection of human hepatitis C virus core antigen (HCV core Ag) taking into account the potential modification with cations in blood serum samples, using mica chips for the atomic force microscopy (AFM-chips). To conduct specific protein fishing, we used flat AFM-chips preliminary sensibilized with molecular probes – aptamers, which are single-stranded DNA sequences. In our study we used four types of aptamers up to 85 nucleotides specific against the target protein – HCVcoreAg [3,4]. Working (n = 19) and control (n = 11) AFM-chips with aptamers were preliminarily immobilized on the surface in four zones and incubated in blood serum samples (See Supplementary fig. 1). Analysis of MS data regarding modification of marker protein peptides with Na+, K+, K2Cl+, and Na2Cl + ions enables to enhance the reliability of target proteins detection in the serum thereby demonstrating a high diagnostic potential.

Optical disc technology-enabled analytical devices: from hardware modification to digitized molecular detection

Beyond their essential applications in portable data storage for the past 30 years, optical discs and corresponding recording/reading technologies have been extensively explored with the ultimate goal of creating novel analytical tools for on-site chemical analysis and point-of-care (POC) medical diagnosis. In particular, the disc media (CD, DVD, and BD) are proven to be inexpensive and versatile substrate materials for the preparation of various biochips and microfluidic systems; conventional computer drives and disc players are widely adapted for biochip signal reading and microscopic imaging. Herein we provide an overview of such optical disc technology-enabled analytical devices, e.g., integrated systems developed from specifically fabricated analog disks, modified optical drives, or adapted software algorithms.

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.