Pavel S. Postnikov

Bio: Pavel S. Postnikov is an academic researcher from Tomsk Polytechnic University. The author has contributed to research in topics: Plasmon & Chemistry. The author has an hindex of 19, co-authored 126 publications receiving 1440 citations. Previous affiliations of Pavel S. Postnikov include Institute of Chemical Technology in Prague & Vanderbilt University.

Pretreatment-free selective and reproducible SERS-based detection of heavy metal ions on DTPA functionalized plasmonic platform

Abstract: Here we report a surface plasmon-polariton based functionalized SERS platform for the detection of heavy metal ions. Homogenous distribution of the plasmon intensity on the ordered plasmon structure and high affinity of diethylenetriaminepentaacetic acid (DTPA) to heavy metal ions allows the efficient entrapping of heavy metal ions as well as their selective and sensitive detection (LOD was found 10−14 M). Periodical gold structure was created using the excimer laser beam treatment of polymer surface and further coating by gold. DTPA molecules were covalently attached to the gold surface through the two step procedure: (i) grafting of 4-aminophenylene groups via diazonium chemistry and (ii) their acylation by DTPA-anhydride. Grafted DTPA molecules showed high SERS response, due to the SPP excitation and propagation on the gold grafting. Efficient chelating of heavy metal ions by DTPA molecules from solution results in pronounced changes of their SERS response. The shift of carbonyl Raman peak position was found to be dependent on the atomic number of heavy metal ions, enabling the selective detection even in the mixture of few metals. Applied SERS platform can be realized using the portable SERS spectrophotometer and requires the minimal equipment cost as well as the experimental time.

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Carbon Nanozymes: Enzymatic Properties, Catalytic Mechanism, and Applications.

Abstract: Nanozymes have advantages over natural enzymes, such as facile production on large scale, long storage time, low costs, and high stability in harsh environments. Carbon nanomaterials (CNMs), including fullerenes, carbon nanotubes, graphene, carbon quantum dots, and graphene quantum dots, have become a star family in materials science. As a new class of nanozymes, the catalytic activity of CNMs and their hybrids has been extensively reported. In this Minireview, recent progress of CNMs based artificial enzymes, focusing on those with peroxidase-like activity, has been summarized. The enzymatic properties, catalytic mechanisms, and novel applications of CNM nanozymes in sensing, therapy, and environmental engineering are discussed in detail. Additionally, we also highlight the remaining challenges and unsolved problems. With the fast development of bionanotechnology, the unique enzymatic properties and advantages of CNM nanozymes have received much attention and will continue to be an active and challenging field for the years to come.

About graphene oxide

Abstract: Popularity of graphene oxide (GO) became ballistic in the last few years – in short, it almost seems that now everyone wants to work with graphene. However, as the number of electrochemical papers about graphene grows, so is the amount of misinterpretations. Our work was mostly focused on preparation of GO and its electrochemical properties, namely catalysis. Our results show, that chemical preparation of GO by strong oxidation is very tricky. Several approaches were tested, such as different sizes of graphite particles, oxidation mixtures, even repetitive preparations under the same conditions usually resulted in different products. Another big topic are impurities which are present due to natural occurrence in graphite and some of them might be also introduced during purification processes of GO. This could also lead to often observed catalytic activity of graphene. From our observations neither selectivity nor significant electrocatalytic abilities of the reduced graphene oxide modified electrodes towards H2O2 were observed. Moreover, our results suggest that GO does not need linking molecules in order to be deposited onto the surface of the electrodes, since it attaches spontaneously and keeps its electrochemical properties. Graphene is usually reported as a superior material, but its proper description and characterization should not be underestimated.