АV

А. V. Ermakov

Molecular Theranostics (United States)

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Ekaterina V. Lengert

Saratov State Medical University

Roman A. Verkhovskii

Saratov State University

B. J. Hinch

Rutgers, The State University of New Jersey

АН

А. Н. Иванов

Saratov State Medical University

Gleb B. Sukhorukov

Queen Mary University of London

Daniil N. Bratashov

Saratov State University

ИМ

И. М. Белоусова

State Optical Institute named after SI Vavilov

ВМ

В. М. Киселев

State Optical Institute named after SI Vavilov

Angelina A. Savkina

Saratov State Medical University

Anastasiia Kozlova

The University of Texas Health Science Center at Houston

Cooperative Institutions

Russian Academy of Sciences

Saratov State University

Saratov State Medical University

Lomonosov Moscow State University

Saratov Research Center

M.N. Mikheev Institute of Metal Physics

Rutgers, The State University of New Jersey

Institute of Physics

Ministry of Health of the Russian Federation

Ural Branch of the Russian Academy of Sciences

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Electron-beam-induced patterned deposition of allylcyclopentadienyl palladium using scanning tunneling microscopy

Journal of Applied Physics (1994)

D. Saulys А. V. Ermakov Eric Garfunkel P. A. Dowben

Scanning tunneling microscopy has been used to study the electron-induced decomposition of allylcyclopentadienyl palladium [Pd(η3-C3H5)(η5-C5H5)] and subsequent deposition on a Si(111) surface. Deposition occurs via an electron impact mechanism on either the tip or surface, depending on the bias polarity, and is observed with voltages of ≥2.75 V. This is close to the predicted condensed phase dissociation energy of 2.3 eV for Pd(η3-C3H5)(η5-C5H5)→Pd+C3H5+C5H5. Metallic deposits of nanometer dimensions can be written on the surface. Deposition onto an electrochemically etched tip results in a narrow conductive secondary tip which gives improved spatial resolution when imaging high-aspect ratio features on the surface.

Deposition

Nanometre

10.1063/1.357935

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Citations (17)

Experimental testing of tannic acid target delivery system for correcting periodontal microcirculation

Saratov Medical Journal (2022)

Angelina A. Savkina Ekaterina V. Lengert А. V. Ermakov Э. Б. Попыхова Tatiana Stepanova

Objective: to study the effect of the targeted delivery system of tannic acid (TA) in silver alginate microcapsules on the state of gum microvasculature in rats with intact periodontium vs. experimental periodontitis. Materials and Methods. The study was conducted on 90 white rats, distributed among six groups: the control group, two groups with intact periodontium and single application of gel with microcapsules loaded/not loaded with TA, experimental periodontitis group, and two groups of animals with periodontitis and repeated application of gel with microcapsules loaded/not loaded with TA. We assessed gingival perfusion and blood flow modulation mechanisms in rats via laser Doppler flowmetry. Results. Applying gel with silver microcapsules to an intact gum in rats caused 7.5% transient increase in perfusion and activation of microcirculation modulation. Loading microcapsules with TA reduced the severity of transient microcirculatory changes. Using gel with TA-loaded capsules in rats with periodontitis allowed achieving a more pronounced normalization of perfusion and mechanisms of microcirculation modulation vs. using gel containing microcapsules without active components. Conclusion. Loading alginate microcapsules with silver ions and TA yielded reduction of the irritating effect on gingival mucosa accompanied by an increase in the effectiveness of correcting microcirculatory disorders in periodontitis.

Periodontium

Tannic acid

10.15275/sarmj.2022.0103

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In vivo study of polyelectrolyte microcarriers loaded with zinc phthalocyanine for image-guided photodynamic therapy

А. V. Ermakov Arthur B. Volovetsky Artyom O. Zvyagintcev Daria B. Trushina Andrei V. Zvyagin

In this work, we investigate a hybrid system based on a biocompatible polymer matrix loaded with a fluorescent photodynamic dye zinc phthalocyanine as a platform with high photodynamic activity in the first biological window and the ability to visualize the biodistribution of the system in vivo. In this regard, biocompatible polyelectrolyte carriers of submicron size were used, which enable efficient immobilization of low-molecular-weight dyes and carry out photodynamic therapy without uncontrolled release of the photodynamic agent. Since the thickness of the polyelectrolyte shell of the carrier do not exceed several tens of nanometers, and the lifetime of singlet oxygen enable motion over distances of up to several microns, the photodynamic activity of the immobilized agent can be observed even without the release of the photodynamic agent from the polyelectrolyte carrier, thus making the carrier itself a photodynamic agent. The ability to flexibly vary the composition of the polyelectrolyte shell of the carriers allows it to include functional organic and inorganic components, which makes it possible to provide the function of visualizing the biodistribution of the delivery system in vivo during circulation in the body. The system described in this work will provide additional functionalization of the carriers, such as the ability to visualization of the biodistribution of submicron polymer carriers loaded with photodynamic agents in laboratory mice in vivo which has been investigated in this work. These results open up a venue for the therapy based on the principles of "image-guided therapy".

Biodistribution

10.1117/12.2626960

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A surface work function measurement technique utilizing constant deflected grazing electron trajectories: Oxygen uptake on Cu(001)

Review of Scientific Instruments (2010)

А. V. Ermakov E. Z. Ciftlikli S. E. Syssoev I.G. Shuttleworth B. J. Hinch

We report on the application of a novel nondestructive in-vacuum technique for relative work function measurements, employing a grazing incidence electron deflection above a sample with a planar surface. Two deflected electron beam detectors are used as a position sensitive detector to control feedback to the sample potential as the sample work function changes. With feedback the sample potential exactly follows the surface sample-size averaged work function variation, so that the deflected beam trajectory remains stable. We also discuss methods to optimize the initial electron trajectories for this method, so as to minimize unwanted effects such as from uncontrolled external magnetic fields. As the electron beam does not impinge on the surface in this new technique electron induced desorption, ionization, dissociation, and/or decomposition is not induced at the interface. Importantly also the technique allows for free access to the surfaces enabling simultaneous deposition/evaporation and/or application of other surface characterization methods. We demonstrate its application in concurrent measurements of helium atom reflectivity and work function changes taking place during molecular oxygen exposure of a Cu(001) surface. A work function measurement sensitivity and stability is demonstrated at ∼10 mV at a sampling rate of 1 Hz and after application of an ∼7 s smoothing routine. In comparison to the helium atom reflectivity measurements, the work function measurements are more sensitive to the initial O uptake, and less so to the final coverage variations and possible surface reordering at higher O coverages.

10.1063/1.3488457

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Extreme electron-hole drag and negative mobility in the Dirac plasma of graphene

arXiv (Cornell University) (2024)

Л. А. Пономаренко Alessandro Principi Andy Niblett Wendong Wang Р. В. Горбачев

Coulomb drag between adjacent electron and hole gases has attracted considerable attention, being studied in various two-dimensional systems, including semiconductor and graphene heterostructures. Here we report measurements of electron-hole drag in the Planckian plasma that develops in monolayer graphene in the vicinity of its Dirac point above liquid-nitrogen temperatures. The frequent electron-hole scattering forces minority carriers to move against the applied electric field due to the drag induced by majority carriers. This unidirectional transport of electrons and holes results in nominally negative mobility for the minority carriers. The electron-hole drag is found to be strongest near-room temperature, despite being notably affected by phonon scattering. Our findings provide better understanding of the transport properties of charge-neutral graphene, reveal limits on its hydrodynamic description and also offer insight into quantum-critical systems in general.

10.48550/arxiv.2410.10640

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Impact of silver nanoparticle concentration in alginate microcapsules on their effects on morphological changes in periodontitis

Saratov Medical Journal (2022)

Angelina A. Savkina Ekaterina V. Lengert А. V. Ermakov Tatyana Stepanova А. Н. Иванов

Objective: to evaluate the effects of alginate microcapsules on morphological changes in periodontitis depending on silver nanoparticle concentration in them. Materials and Methods. The study was conducted on 30 rats distributed among three groups of 10 animals: the comparison group comprising animals with an experimental model of periodontitis and two experimental groups including animals with 5-week periodontitis, which were subjected to applications of the gel containing microcapsules with high (0.25 M, Group 1) and low (0.1 M, Group 2) concentrations of silver on the surface of their gums. To assess morphological changes, the mandible was sampled for subsequent examination. Results. In animals with periodontitis, changes in the supporting structure of the tooth took place, including defibration and perivascular edema in periodontal ligament of the tooth, and bone resorption via its replacement with connective tissue. The application of a gel containing microcapsules with silver nanoparticles led to a partial reduction of such disorders: particularly, it reduced bone resorption and its replacement with connective tissue. Destructive changes in periodontal tissues caused by gel with a high content of silver nanoparticles (0.25 M) were less pronounced than those caused by capsules with a low content of silver (0.1 M). Conclusion. Gels containing microcapsules with silver nanoparticles contributed to the reduction of destructive changes in the supporting structure of the tooth in periodontitis. The severity of the effects of the gel increased with an increase in the content of silver nanoparticles in alginate microcapsules.

Silver nanoparticle

10.15275/sarmj.2022.0401

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Cu(001) to HD energy transfer and translational to rotational energy conversion on surface scattering

The Journal of Chemical Physics (2001)

Lyudmila V. Goncharova J. Braun А. V. Ermakov G. G. Bishop Detlef‐M. Smilgies

Intense peaks are observed in angular intensity distributions for HD scattering from the Cu(001) surface. These can be ascribed to coherent diffraction with translational energy transfers of ΔE=0, −11.0, or 33.11 meV to molecular rotational energy. Time-of-flight spectra, at other scattering angles, display inelastic peaks that are assigned to phonon creation or annihilation processes with either the HD rotationally elastic or inelastic transitions. The HD phonon dispersion curves suggest a strong HD coupling both with surface Rayleigh modes and with bulk phonon modes of the metal surface. Comparisons of both elastic and inelastic scattering intensities are also made with those reported for the Ni(001) surface. To explain an apparent anomalous diffraction peak intensity ratio for Ni, a preferential coupling for the HD J=0 rotational state into a predissociation channel above the Ni surface is proposed.

Surface phonon

10.1063/1.1403001

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Citations (22)

Preparation and Properties of Nanocolloidal Rhenium Sulfide Solution for Lymphoscintigraphic Methods of Micrometastase Examination

Applied Biochemistry and Microbiology (2017)

B. M. Manuilov А. V. Ermakov

10.1134/s000368381708004x

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Electrical Characterization of Micron-Sized Chambers Used as a Depot for Drug Delivery

IEEE Sensors Journal (2022)

Ahsan Noor Khan А. V. Ermakov Theo Saunders Henry Giddens David Gould

Implantable drug delivery devices have emerged as a quintessential therapeutic platform for curing chronic ailments that require enhanced and localized drug concentrations. A typical device encompasses an array of tiny reservoirs or chambers to store drug formulations before their release inside a biological milieu. With the recent progress in biocompatible and biodegradable materials, it has become readily possible to fabricate chambers for rapid and on-demand drug release. However, to deal with an emerging diagnostic and therapeutic conundrum, new paradigms are required to devise chambers with multifunctional capabilities. In this article, we present micrometer-sized chambers that are fabricated by a patterned film base to realize their structure in an array formation. The microchambers are fabricated from a polylactic acid matrix and modified with a range of conducting species using the layer-by-layer (LBL) assembly technique. For electrical response characterization of microchambers, a complementary split ring resonator (CSRR) is used to estimate the loss tangent. A proof of concept is also discussed that the conductive nature of microchambers can be envisioned to perform thermal therapy and drug delivery in response to electromagnetic radiations.

Biocompatible material

10.1109/jsen.2022.3194717

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Dissociative and molecular adsorption and recombinative desorption of methylchlorosilanes at the Cu (001) surface

Bulletin of the American Physical Society (2007)

James Lallo Lyudmila V. Goncharova А. V. Ermakov B. J. Hinch Daniel R. Strongin

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