Biology subjects

Zavyalova, E.

Publications and source records attributed to Zavyalova, E..

4 recordsLinked to original sources

bioRxiv2025

Surface-enhanced Raman spectroscopy on the membranes for antimicrobial resistance testing

Antimicrobial resistance is one of the top global health threats; it is associated with millions of deaths per year. Traditional and most commonly used antibiotic susceptibility tests are based on detection of bacterial growth and its inhibition in the presence of an antimicrobial. These tests typically take over 1-2 days to perform, so empirical therapy schemes are often administered before the proper testing. Rapid tests for antimicrobial resistance are necessary to optimize the treatment of bacterial infection. A combination of MTT test with Raman spectroscopy to provide 1.5-hour long test antimicrobial susceptibility determination requiring 106-108 CFU/mL of bacteria. Here the first rapid antibiotic susceptibility test for trace amounts of bacteria is described. The bacterial titer can be decreased down to 102 CFU/mL using surface-enhanced Raman spectroscopy (SERS) of the MTT-treated bacteria caught with the silver coated track-etched membranes allowing the antimicrobial testing of low-titer bacterial samples within 1.5 hour. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=109 SRC="FIGDIR/small/664554v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@1e241c5org.highwire.dtl.DTLVardef@14c071forg.highwire.dtl.DTLVardef@67aad7org.highwire.dtl.DTLVardef@140db_HPS_FORMAT_FIGEXP M_FIG C_FIG A combination of MTT test with membrane filtration and surface-enhanced Raman spectroscopy is used to determine antibiotic susceptibility of E.col

microbiology↗

bioRxiv2025

Ag+-regulated aptamers to thrombin

Nucleic acid aptamers are artificial recognition elements with high potential in biotechnology. Approaches for aptamer affinity optimization and activity regulation are required for aptamer-based nanodevices. Here thrombin aptamer affinity was increased by a single nucleotide modification with 7,8-dihydro-8-oxo-1,N6-ethenoadenine. Whereas a double modification makes the aptamer activity Ag+-dependent.

biochemistry↗

bioRxiv2024

Kinetics of i-motif folding within the duplex context

Non-canonical nucleic acid structures possess an ability to interact selectively with proteins, thereby exerting influence over various intracellular processes. Numerous studies indicate that genomic G-quadruplexes and i-motifs are involved in the regulation of transcription. These structures are formed temporarily during the unwinding of the DNA double helix; and their direct determination is a rather difficult task. In addition, i-motif folding is pH-dependent, with most i-motifs having low stability at neutral pH. However, some genomic i-motifs with long cytosine repeats were shown to be stable at pH 7.3, suggesting their functionality within the nucleus. Here we studied pH-dependent behavior of a model i-motif with flanking sequences that forms a duplex motif. Kinetic studies on bimodular structures with cytosine residues replaced with an environment-sensitive fluorescent label reveal the stabilization of the i-motif structure near the i-motif-duplex junction. These results highlight the importance of the natural environment of i-motifs for the correct assessment of their stability.

biochemistry↗

bioRxiv2024

Rapid Raman spectroscopy-based test for antimicrobial resistance

Antimicrobial resistance is one of the top global health threats. In 2019, antimicrobial resistance was associated with 4.95 million deaths, of which 1.97 million were caused by drug resistant infections directly. The main subset of AMR is the antibiotic resistance, that is resistance of bacteria to antibiotic treatment. Traditional and most commonly used antibiotic susceptibility tests are based on detection of bacterial growth and its inhibition in the presence of an antimicrobial. These tests typically take over 1-2 days to perform, so empirical therapy schemes are often administered before the proper testing. Rapid tests for antimicrobial resistance are necessary to optimize the treatment of bacterial infection. Here we combine MTT test with Raman spectroscopy to provide 1.5-hour long test for minimal inhibitory concentrations determination. Several E.coli and K.pneumoniae strains were tested with three types antibiotics, including ampicillin from penicillin family, kanamycin from aminoglycoside family and levofloxacin from fluoroquinolone family. The test provided the same minimal inhibitory concentrations as traditional Etest confirming its robustness.

molecular biology↗