Lidé

Ing. Jaroslav Jíra, CSc.

Všechny publikace

Bactericidal effect of zinc oxide nanoparticles on Gram-positive and Gram-negative strains in reverse spin bioreactor

  • DOI: 10.1088/1757-899X/1050/1/012013
  • Odkaz: https://doi.org/10.1088/1757-899X/1050/1/012013
  • Pracoviště: Katedra fyziky
  • Anotace:
    We present an experimental study investigating the efficacy of zinc oxide nanoparticle use for bacterial decontamination of water using reverse spin technology. The number of viable bacteria reduced with treatment time and the rate of inactivation was dependent on zinc oxide concentration. Gram-positive S. aureus bacteria were more resistant to zinc oxide nanoparticles compared to Gram-negative E. coli, however both strains were completely eradicated after 4 hours using a concentration of 10 μg/mL. Nanoparticles did not inhibit growth of bacteria when added to an agar surface, neither when in liquid before bacteria inoculation nor when loaded onto filter paper disks after bacteria inoculation. These results emphasise the importance of efficient reactor mixing to enhance interaction capability for ZnO use in water decontamination.

Effect of ZnO nanoparticle sizes and illumination on growth inhibition of Escherichia coli and Staphylococcus aureus bacteria in cultivation medium

  • DOI: 10.1088/1757-899X/1050/1/012007
  • Odkaz: https://doi.org/10.1088/1757-899X/1050/1/012007
  • Pracoviště: Katedra fyziky
  • Anotace:
    We study antibacterial effects of the zinc oxide nanoparticles (ZnO NPs) in cultivation medium (Mueller-Hinton broth) on Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria models. We compare synthesized ZnO hedgehog NPs and commercial ZnO NPs (50 nm and 20 μm nominal size) in different concentrations (1 mg/mL and 0.1 mg/mL). Results show that E. coli are more sensitive to the ZnO presence in the cultivation media than S. aureus. We also characterize influence of visible and UV light on the ZnO NP effects.

Growth Inhibition of Gram-Positive and Gram-Negative Bacteria by Zinc Oxide Hedgehog Particles

  • DOI: 10.2147/IJN.S300428
  • Odkaz: https://doi.org/10.2147/IJN.S300428
  • Pracoviště: Katedra fyziky
  • Anotace:
    Purpose: Nanomaterials for antimicrobial applications have gained interest in recent years due to the increasing bacteria resistance to conventional antibiotics. Wound sterilization, water treatment and surface decontamination all avail from multifunctional materials that also possess excellent antibacterial properties, eg zinc oxide (ZnO). Here, we assess and compare the effects of synthesized hedgehog-like ZnO structures and commercial ZnO particles with and without mixing on the inactivation of bacteria on surfaces and in liquid environments.

Microscopic Study of Bovine Serum Albumin Adsorption on Zinc Oxide (0001) Surface

  • DOI: 10.1002/pssa.202000558
  • Odkaz: https://doi.org/10.1002/pssa.202000558
  • Pracoviště: Katedra fyziky
  • Anotace:
    Properties and functions of various ZnO materials are intensively investigated in biological systems for diagnostics, therapy, health risks assessment as well as bactericidal and decontamination purposes. Herein, the interface between ZnO and biological environment is studied by characterizing adsorption of bovine serum albumin (BSA) and fetal bovine serum (FBS) using atomic force microscopy with CF4-treated tips. Similar molecular morphologies (thickness around 2 nm) yet different binding forces to ZnO (10–25 nN) are observed. These observations are corroborated by atomic scale simulations of BSA on (0001) ZnO surface using force-field method and showing rearrangements of Zn surface atoms. Such binding may have an impact also on other properties of ZnO–BSA complex.

PLASMA-SYNTHESISED ZINC OXIDE NANOPARTICLE BEHAVIOR IN LIQUIDS

  • DOI: 10.37904/nanocon.2021.4318
  • Odkaz: https://doi.org/10.37904/nanocon.2021.4318
  • Pracoviště: Katedra fyziky
  • Anotace:
    Zinc oxide nanoparticles have been synthesized using non-thermal atmospheric pressure plasma (ZnO-NTP). We investigated the behavior of these ligand-free as a colloid suspension using different solvents, from deionized water to physiological saline and microbial culture broth. We found that the zeta potential of ZnO-NTP became more negative after exposure to microbial culture broth relative to water, which suggests increased colloid stability. Photoluminescence spectra of ZnO-NTP were similar regardless of liquid type, yet optical and fluorescent images of samples showed different agglomeration behavior depending on liquid type. Scanning electron microscopy images revealed large agglomerates of ZnO-NTP interacting with the surface of bacteria cells, ranging in size from 200 nm up to 2 µm. We also studied effect of sub-lethal concentrations of ZnO-NTP on bacteria under illumination. There was no significant difference in viable bacteria concentration after 24h exposure to 10 µg/mL ZnO-NTP relative to untreated control irrespective of sample illumination.

COMPARISON OF MICROBIAL INTERACTIONS OF ZINC OXIDE NANOMATERIALS IN VARIOUS SIZE AND SHAPE

  • DOI: 10.37904/nanocon.2019.8666
  • Odkaz: https://doi.org/10.37904/nanocon.2019.8666
  • Pracoviště: Katedra fyziky
  • Anotace:
    Zinc oxide nanoparticles (ZnO NP) have shown great potential as a novel antibacterial material at a time when resistance towards conventional antibiotics is becoming more prevalent. We report bacteria inactivation by ZnO NP with novel hedgehog-like morphology using model gram-negative (E. coli) and gram-positive (S. aureus) bacteria. E. coli exposed to the novel ZnO hedgehog NP during growth resulted in 4 orders of magnitude reduction in viable cell concentration after 24 h, which is more than 2 orders higher reduction compared to commercially available ZnO NPs with nominal sizes from 50 nm to 20 um. There was a positive correlation between hedgehog NP concentration and bacteria cell concentration reduction within the range tested 0.1 – 1.0 mg/mL. S. aureus was less sensitive to ZnO NP exposure and inactivation effect of various ZnO NP was comparable. The effect can be thus atrributed to direct mechanical damage of the bacterial mebrane that is the most effective for the novel hedgehog ZnO NP. This conclusion was corroborated also by disk diffusion assays

Inhibition of E. coli Growth by Nanodiamond and Graphene Oxide Enhanced by Luria-Bertani Medium

  • DOI: 10.3390/nano8030140
  • Odkaz: https://doi.org/10.3390/nano8030140
  • Pracoviště: Katedra fyziky
  • Anotace:
    Nanodiamonds (NDs) and graphene oxide (GO) are modern carbon-based nanomaterials with promising features for the inhibition of microorganism growth ability. Here we compare the effects of nanodiamond and graphene oxide in both annealed (oxidized) and reduced (hydrogenated) forms in two types of cultivation media—Luria-Bertani (LB) and Mueller-Hinton (MH) broths. The comparison shows that the number of colony forming unit (CFU) of Escherichia coli is significantly lowered (45%) by all the nanomaterials in LB medium for at least 24 h against control. On the contrary, a significant long-term inhibition of E. coli growth (by 45%) in the MH medium is provided only by hydrogenated NDs terminated with C-HX groups. The use of salty agars did not enhance the inhibition effects of nanomaterials used, i.e. disruption of bacterial membrane or differences in ionic concentrations do not play any role in bactericidal effects of nanomaterials used. The specific role of the ND and GO on the enhancement of the oxidative stress of bacteria or possible wrapping bacteria by GO nanosheets, therefore isolating them from both the environment and nutrition was suggested. Analyses by infrared spectroscopy, photoelectron spectroscopy, scanning electron microscopy and dynamic light scattering corroborate these conclusions.

Surface chemistry of water-dispersed detonation nanodiamonds modified by atmospheric DC plasma afterglow

  • DOI: 10.1039/c7ra04167e
  • Odkaz: https://doi.org/10.1039/c7ra04167e
  • Pracoviště: Katedra fyziky
  • Anotace:
    Surface modification of detonation nanodiamonds (DNDs) is a key factor for their application in diverse fields of science and technology. In this work we report on an easy and low-cost method for modifying water-dispersed DNDs by atmospheric DC plasma afterglow. DNDs were used in either as-received form (asrec-DND) or were oxidized by air-annealing at 450 °C for 30 minutes (O-DND). The influence of applied voltage and thus the type of discharge (corona discharge at 10 kV or transient spark discharge at 15 kV) and treatment duration (5 and 10 minutes) on the surface chemistry of DNDs was evaluated by Fourier Transform Infrared (FTIR) spectroscopy supported by X-ray photoelectron spectroscopy (XPS) and dynamic light scattering (DLS). Treated asrec-DNDs revealed stable positive ζ-potential (30 mV) during rearrangement of oxygen-containing moieties (changes in area below 1250 cm−1) as well as CHx groups, reflected in the enormous enhancement of the band at 1328 cm−1 and disappearance of the C[double bond, length as m-dash]C band at 1589 cm−1. On the other hand, the DC discharge afterglow had only minor impact on the surface chemistry of O-DND particles, as detected by FTIR and XPS, while a negative change of ζ-potential by up to 22 mV occurred. O-DND particles dried in vacuum also exhibited a noticeable catalytic effect towards hydrocarbons.

Bacterial response to nanodiamonds and graphene oxide sheets

  • DOI: 10.1002/pssb.201600237
  • Odkaz: https://doi.org/10.1002/pssb.201600237
  • Pracoviště: Katedra fyziky
  • Anotace:
    Carbon nanomaterials such as nanodiamond (ND) and graphene oxide (GO) attract increasing attention for biomedical applications due their unique and adjustable properties. Here we report on antibacterial activity of NDs and GO as evaluated by bacterial colony counting. ND and GO were used in oxidized (O-ND, GO) or reduced (H-ND, rGO) forms. ND or GO are mixed in Mueller–Hinton (MH) broth with Escherichia coli at the concentration of 1 mg ml−1. The resulting suspensions were cultivated for 5 and 24 h at 37 °C in a shaker. After each period, a sample of the suspension was spread on the MH agar and cultivated for 24 h at 37° C. The effect of nanomaterials on colony forming ability (CFA) of E. coli was evaluated and compared with the negative control sample. The most noticeable effect was that after 5 h H-ND decreased the CFA of E. coli in the MH broth by 60% and GO by 50%. After 24 h, H-ND decreased CFA by 50%. Other nanomaterials had no statistically significant antibacterial effect. Factors influencing ND and GO antibacterial activity against the E. coli and possibly against other bacteria are discussed.

Impact of Low Frequency Electromagnetic Field Exposure on Selected Microorganisms

  • Autoři: Malikova, I., Janousek, L., Fantova, V., Ing. Jaroslav Jíra, CSc., Kříha, V.
  • Publikace: 38th International Conference on Telecommunications and Signal Processing. Piscataway: IEEE, 2015. p. 408-411. ISSN 1805-5435. ISBN 978-1-4799-8498-5.
  • Rok: 2015
  • Pracoviště: Katedra fyziky
  • Anotace:
    Effects of short term exposure on two selected microorganisms by a low frequency electromagnetic field are studied in the article. One of the most radiation resistant bacterium and commensal bacterium normally occurring in gastrointestinal tracts of mammals are chosen for this research. The theory of ion parametric resonance is taken as the base for studying the influence of the electromagnetic field on biological structures. Specific measurements are performed according to this theory in order to evaluate the impact. The electromagnetic treatment influences the growth rate of both bacteria. The methods and results of experiments are described and discussed in the article.

Impact of Low Frequency Electromagnetic Field on the Candida albicans.

  • Autoři: Malíková, I., Janoušek, L., Fantova, V., Ing. Jaroslav Jíra, CSc., Kříha, V.
  • Publikace: Journal of Electrical Engineering. 2015, 66(2), 108-112. ISSN 1335-3632.
  • Rok: 2015
  • DOI: 10.1515/jee-2015-0017
  • Odkaz: https://doi.org/10.1515/jee-2015-0017
  • Pracoviště: Katedra fyziky
  • Anotace:
    Effect of low frequency electromagnetic field on growth of selected microorganism is studied in the article. The diploid fungus that grows both as yeast and filamentous cell was chosen for this research. The theory of ion parametric resonance was taken as the base for studying the influence of electromagnetic field on biological structures. We tested the hypothesis, whether it is possible to observe the change in growth properties of Candida albicans with an AC electromagnetic field tuned to resonance with calcium ions cyclotron frequency.

Skupina biomedicínského inženýrství

  • Pracoviště: Katedra fyziky, Katedra kybernetiky
  • Anotace:
    Článek popisuje vznik, působení, hlavní směry výzkumu a vyučované předměty skupiny biomedicínského inženýrství na katedře fyziky ČVUT FEL

Elektroterapie ve sportovní medicíně

  • Autoři: Slovák, P., Ing. Jaroslav Jíra, CSc.,
  • Publikace: MEDSOFT 2000. Praha: TECH-MARKET, 2000, ISBN 80-86114-31-7.
  • Rok: 2000

Za stránku zodpovídá: Ing. Mgr. Radovan Suk