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Bacteriostatic Effects of Apatite-Covered Ag/AgBr/TiO Nanocomposite in the Dark: Anomaly in Bacterial Motility Seyedsaeid Ahmadvand, Mohammadreza Elahifard, Mehdi Jabbarzadeh, Amir Mirzanejad, Kathryn Pflughoeft, Bahman Abbasi, and Behrooz Abbasi J. Phys. Chem. B, Just Accepted Manuscript • DOI: 10.1021/acs.jpcb.8b10710 • Publication Date (Web): 08 Jan 2019 Downloaded from http://pubs.acs.org on January 9, 2019
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The Journal of Physical Chemistry
Bacteriostatic Effects of Apatite-Covered Ag/AgBr/TiO2 Nanocomposite in the Dark: Anomaly in Bacterial Motility Seyedsaeid Ahmadvand,1 Mohammadreza Elahifard,2 Mehdi Jabbarzadeh,3 Amir Mirzanejad,2 Kathryn Pflughoeft,4 Bahman Abbasi,5 Behrooz Abbasi6 1Department 2Chemical
of Chemistry, University of Nevada, Reno, Reno, NV 89557, U.S.A.
Engineering Department, Faculty of Engineering, Ardakan University, Ardakan, Iran
3Department
of Mechanical Engineering, University of Utah, Salt Lake City, UT 84112, USA
4Department
of Microbiology and Immunology, University of Nevada School of Medicine, Reno, NV 89557, U.S.A.
5Department
of Mechanical Engineering, Oregon State University, Corvallis, OR 97333, U.S.A.
6Department
of Metallurgical Engineering, University of Nevada, Reno, Reno, NV 89557, U.S.A.
[email protected] 1
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ABSTRACT: In this paper, we report a unique property of inactivating Gram-positive/negative bacteria in the dark via apatite-covered Ag/AgBr/TiO2 nanocomposites (AAAT). We demonstrate that the inactivation mechanism is bacteriostatic based on the cellular integrity and motility of bacteria, and low toxicity and high durability of AAAT. From straight observations, the catalytic loading affects the bacterial replication and cell envelope, as well as inducing an anomaly in bacterial motility (continuous rotation) for both types of bacteria. Both simulation and experimental analyses suggest that the anomaly could be due to posterior intracellular signals rather than purely mechanical effects (e.g., size enlargement and motility retardation). Provoked by chemo-mechanical stimuli, these signals increase the frequency of flagellar tumbling and eventually entangle the bacteria.
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The Journal of Physical Chemistry
1. INTRODUCTION Most antibiotics are bactericidal and inactivate bacteria via lysis (e.g., penicillin).1–4 Apart from lysis, chemicals can inactivate bacteria by changing the cellular biochemistry, motility, and reproduction.5–8 When a bacterial cell encounters an chemoattractant or a repellant that binds to a chemoreceptor, a ligand-induced conformational change may occur in the chemoreceptor.9–12 The downstream effect is a change in the ratio of the concentration of phosphorylated to unphosphorylated forms of the CheY protein and thereby flagellar motion.13,14 Bacteria tumble less frequently facing an attractant and more frequently facing a repellent, governed by the concentration of phosphorylated CheY.13–18 Other stimuli can also disrupt bacterial motility, such as catalytic loading of bacteria.8 The scope of action, toxicity, and durability are three major concerns in the synthesis of bacteriostatic materials.19–26 Numerous studies have reported bacteriostatic effects of materials, in which silver, titanium, and phosphate components are individually and combinatorially present.27– 31
These effects become more prominent when all aforementioned compounds exist
simultaneously.32–35 For instance, a bacteriostatic activity has been reported for the porous material, AgTi2(PO4)3, with a very small out-leaching of Ag+ ion (
