Subscriber access provided by Technical University of Munich University Library
Biological and Medical Applications of Materials and Interfaces
Antibacterial Performance of TiCaPCON Films Incorporated with Ag, Pt and Zn: Bactericidal Ions versus Surface Micro-Galvanic Interactions Viktor Ponomarev, Irina V. Sukhorukova, Alexander Nikolaevich Sheveyko, Elizaveta S. Permyakova, Anton M. Manakhov, Sergei G. Ignatov, Natalya Gloushankova, Irina Zhitnyak, Oleg Igorevich Lebedev, Josef Pol#ák, Aleksander Kozmin, and Dmitry V. Shtansky ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b06671 • Publication Date (Web): 03 Jul 2018 Downloaded from http://pubs.acs.org on July 7, 2018
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
Antibacterial Performance of TiCaPCON Films Incorporated with Ag, Pt and Zn: Bactericidal Ions versus Surface Micro-Galvanic Interactions V.A. Ponomarev,† I.V. Sukhorukova,† A.N. Sheveyko,† E.S. Permyakova,† A.M. Manakhov,† S.G. Ignatov,‡ N.A. Gloushankova,§ I.Y. Zhitnyak,§ O.I. Lebedev,£ J. Polčak,¥ A.M. Kozmin,€ D.V. Shtansky*† †
National University of Science and Technology “MISIS”, Leninsky prospect 4, Moscow 119049, Russia
‡
State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region 142279, Russia
§
N.N Blokhin Russian Cancer Research Center of RAMS, Kashirskoe shosse 24, Moscow 115478, Russia
£
CRISMAT, UMR 6508, CNRS-ENSICAEN, 6Bd Marechal Juin, 14050 Caen, France
¥
Brno University of Technology, Technicka 2896/2, 616 69 Brno, Czech Republic
€
National Research University of Electronic Technology “MIET”, Shokin Square 1, Zelenograd, Moscow Region 124498, Russia
KEYWORDS: Antibacterial films, bactericide ion release, electrochemical behavior, Kelvin probe force microscopy, micro-galvanic effect, cytocompatibility
ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ABSTRACT: It is very important to prevent bacterial colonization at the early postoperative stages. There are four major strategies and their corresponding types of antibacterial surfaces specifically designed to fight infection: bactericide release, anti-adhesion, pH-sensitive, and contact-killing. Herein we aimed at determining antibacterial efficiency of different types of bactericidal ions and revealing the possible contribution of surface micro-galvanic effects arising from a potential difference on heterogeneous surfaces. We considered five types of TiCaPCON films with Ag, Zn, Pt, Ag+Zn, and Pt+Zn nanoparticles (NPs) on their surface. The Ag-modified film demonstrated a pronounced antibacterial effect at a very low Ag ion concentration of 0.11 ppb in physiological solution that was achieved already after 3 h immersion in E. coli bacterial culture. The Zn-containing sample also showed a noticeable antibacterial effect against E. coli and S. aureus strains, wherein the concentration of Zn ions was two orders of magnitude higher (15 ppb) compared with Ag ions. The presence of Ag NPs accelerated Zn ion leaching out of the TiCaPCON-Ag-Zn film, but no synergistic effect of simultaneous presence of the two bactericidal components was observed. After incubation of the samples with Ag, Zn, and Ag+Zn NPs in E. coli and S. aureus suspensions for 24 an 8 h, respectively, all bacterial cells were completely inactivated. The Pt-containing film showed very low Pt ion release and therefore the contribution of this type of ions to the total bactericidal effect could be neglected. The results of electrochemical studies and Kelvin probe force microscopy indicated that micro-galvanic couples were formed between the Pt NPs and TiCaPCON film, but no noticeable antibacterial effect against either E. coli or S. aureus strains was observed. All ion-modified samples provided good osteoblastic cell attachment, spreading, and proliferation, and therefore were concluded to be non-toxic for cells. In addition, the TiCaPCON films with Ag, Pt, and Zn NPs on their surface demonstrated good osteoconductive characteristics.
2 ACS Paragon Plus Environment
Page 2 of 42
Page 3 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
1. INTRODUCTION
The development and fabrication of antibacterial yet biocompatible surfaces are still a challenge whose solution will significantly improve the quality of healthcare and human life. Surface engineering is a powerful tool that allows one to endow a surface with desired combination of physical, chemical, mechanical, and biological characteristics without affecting the material bulk properties. There are four main types of antibacterial surfaces designed to fight infection, their main bacteria-killing mechanisms being: (i) bactericide release, (ii) anti-adhesion (also called as bacterial-repelling or anti-fouling), (iii) pH-sensitive (bacteria-triggered), and (iv) contact-killing.1 The release-based strategy implies the presence of antimicrobial agents such as metal nanoparticles (Ag,2-5 Cu,6,7 Au,8,9 Zn10), different types of antibiotics,5,11,12 quaternary ammonium compounds,13 halogenide-related species (fluoride,14 iodine15), chlorhexidine,16 nitric oxide,17 and chitosan.18 The antibiotic release approach has certain limitations such as a shortterm antibacterial effect, multiple drug resistance, and possibly adverse side effects. The controlled release of metallic ions is difficult to achieve because the ion release rate does not always depend on the bactericide element concentration, and additional factors, such as the state of metal agglomeration, surface roughness, and kinetics of surface oxidation, play a critical role.19 Recent studies clearly demonstrated no direct correlation between bactericide ion leaching and antibacterial properties.19,20 In contrast, the cytocompatibility of materials is known to be dose dependent, therefore the concentration of bactericidal elements must be low. To prevent the formation of a biofilm during the whole duration of rehabilitation period, the antibacterial properties should be maintained for several months, until complete osteointegration. However, the concentration of bactericide component in the near-surface layer reduces over time, resulting in inevitable deterioration of antibacterial characteristics. The anti-adhesion approach is based on preventing bacteria adsorption on the surface. The adsorption of bacteria is the first step of biofilm formation followed by attachment and colonization.21 The bacterial adhesion mechanism depends on the type of microbial species,12 but electrostatic interaction between bacteria and implant surface is the most common. The bacterial adhesion can be controlled via surface wettability.22,23 Since bacteria are more effectively adsorbed on hydrophobic surfaces, the fabrication of hydrophilic, highly hydrated, and uncharged surfaces can significantly reduce the probability of bacterial adhesion. Good surface wettability is also favorable for enhanced cell attachement, spreading, and proliferation.24 The bacteria-triggered approach is based on the bacterial metabolism, which generates acidic substance leading to a pH decrease in the body fluid.25,26 Thus materials release
3 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 4 of 42
antibacterial agent only when bacteria approach their surface and the acidity of the medium changes. The search for alternatives to the standard methods of preventing bacterial colonization led to the development of contact-killing surfaces that do not contain toxic agents. This approach includes the fabrication of a special surface topography, inclusion of cationic compounds in the coating or involvement of micro-galvanic effect. Such micro-galvanic effects are caused by local electrical currents arising from the potential difference between coating phase components (metallic nanoparticles (NPs) on the surface (cathodes) and surrounding conductive matrix (anode)) in a conductive liquid medium (physiological solution). Due to anode dissolution, the electrons generated via reaction (1) pass through coating matrix to the metallic NPs and participate in the depolarization reactions (2) and (3) with the electrolyte molecules. The electrical circuit is closed by transferring negatively charged ions through the electrolyte to the anode. In case of Ti-based coating matrix, the above mentioned chemical reactions can be described as follows: Ti → Tin+ + ne-
(1)
2H2O + 2e- → H2 + 2OH-
(2)
O2 + 2H2O + 4e- → 4OH-
(3)
Note, however, there is very little direct evidence that bacteria can be killed through direct micro-galvanic interactions. For example, micro-galvanic effect between Ag NPs and Ti matrix was studied by Cao et al.27,28 via measuring electrochemical polarization and Zeta potential. The results indicated that Ag-modified surfaces were able to reduce significantly the proliferation of S. aureus and E. coli bacteria despite very low Ag content (
