Surface Modifications of Titanium With Covalently-Bonded Silver Nanoparticles for Antimicrobial Applications

2019 ◽  
Author(s):  
Shahrima Maharubin ◽  
Xiaomei Shu ◽  
Manavi Singh ◽  
Benildo De los Reyes ◽  
George Tan
Keyword(s):  
Silver Nanoparticles ◽  
Film Structure ◽  
Bacterial Attachment ◽  
Covalent Attachment ◽  
Implant Surface ◽  
Covalent Bonds ◽  
Surface Profiling ◽  
Short Term Exposure ◽  
Covalently Bonded ◽  
Effective Remedy

Abstract Formation of biofilm on implant surface is one of the major causes for port-operative infection. Incorporation of antimicrobial silver nanoparticles (AgNPs) on implant surface has been studied as an effective remedy in recent decades. This paper presents a novel AgNPs-titanium composite foil manufactured through covalent attachment of AgNPs for biofilm control. This composite foil was fabricated by a series of chemical reactions including thiol-derivatization and formation of Ag-S covalent bonds. The film structure and properties were characterized through scanning electron microscopy (SEM), Energy dispersive X-ray Spectroscopy (EDS) and surface profiling. The antimicrobial performance was examined against gram positive bacterial strain Staphylococcus aureus. Results indicate that the prepared composite foil effectively reduced bacterial attachment in short term exposure and possess high stability against the release of nanoparticles. This novel antimicrobial composite material has a great potential to be used in the future biomedical instrumentation.

Antibacterial Activity of Biodegradable Particles based on Chitosan Containing Colloidal Silver

2020 ◽  
Vol 36 (4) ◽  
pp. 87-93
Author(s):  
V.Yu. Reshetova ◽  
A.F. Krivoshchepov ◽  
I.A. Butorova ◽  
N.B. Feldman ◽  
S.V. Lutsenko ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Polymer Matrix ◽  
Adipic Acid ◽  
Antibacterial Effect ◽  
Academic Excellence ◽  
Colloidal Silver ◽  
Scanning Electron Microscopy Data ◽  
Covalent Bonds ◽  
Agar Diffusion Test

Chitosan beads with colloidal silver nanoparticles inclued in the polymer matrix have been obtained by the introduction of chitosan into an acidified nanosilver sol. Dual interconnection of drops of the resulting solution was then carried out by ionotropic gelation at the first stage and covalent crosslinking of the polymer matrix with adipic acid at the second stage. The surface morphology of the obtained beads was studied by scanning electron microscopy. Data of Fourier transform IR spectroscopy confirmed the formation of covalent bonds between chitosan and adipic acid. The antibacterial activity of obtained beads against S. aureus and E. coli was evaluated using agar diffusion test. It was shown that the сhitosan beads modified with nanostructured silver exhibited an antibacterial effect against the tested strains, and they can be used as a basis for creating biodegradable wound healing dressings with a prolonged antibacterial effect. chitosan, silver nanoparticles, antibacterial activity, wound dressings This work was supported by the "Russian Academic Excellence Project 5-100". The study was carried out with the financial support of the Russian Foundation for Basic Research in the framework of the Scientific Project no. 18-29-18039.

scholarly journals Evaluation of Changes Induced in the Probiotic Escherichia coli M17 Following Recurrent Exposure to Antimicrobials

2021 ◽  
pp. 158-167
Author(s):  
M. J. A. Mbarga ◽  
I. V. Podoprigora ◽  
E. G. Volina ◽  
A. V. Ermolaev ◽  
L. A. Smolyakova
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Silver Nanoparticles ◽  
Biofilm Formation ◽  
Fold Increase ◽  
Bacterial Attachment ◽  
Diffusion Method ◽  
Cross Resistance ◽  
Microdilution Method ◽  
Similar Work

Introduction: It is already well known that the exposure of certain bacteria, pathogenic or not, to antimicrobials is likely to increase their virulence and induce the development of direct or cross resistance to antimicrobials, but there is almost no information available regarding probiotics. Aim: To assess the changes induced in susceptibility to antibiotics, biofilm formation, growth rate and relative pathogenicity in the probiotic Escherichia coli M17 (EC-M17) after long exposure to antimicrobials namely ampicillin, kanamycin, cefazolin and silver nanoparticles (AgNPs). Methods: After determining the minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of the 4 antimicrobials above-mentioned by the microdilution method, EC-M17 was exposed to increasing subinhibitory doses ranging from MIC/8 to MIC for 8 days. The susceptibility to antibiotics of the mutants obtained was assessed by the Kirby Bauer disc diffusion method, biofilm formation by the Congo red agar method and with crystal violet bacterial attachment assay, and relative pathogenicity was assessed using a Galleria melonella waxworm model. Results: Exposure to antimicrobials induces noticeable changes in EC-M17. The highest adaptation to antimicrobials was observed on AgNPs with 8-fold increase in MIC and 16-fold increase in MBC of AgNPs. EC-M17 exposed to ampicillin, kanamycin and silver nanoparticles became resistant to ampicillin, ceftazidime, ceftazidime/clavulanate and tetracycline while exposure to cefazolin induced a significant decrease in sensitivity to tetracycline and ampicillin and resistance to ceftazidime/clavulanate and ceftazidime. The strain exposed to ampicillin was the only one to produce more biofilm than the control strain and except the EC-M17 exposed to cefazolin, all other EC-M17 strains were more pathogenic on G. melonella model than the control. Conclusion: Data in this investigation suggest that repeated exposure of the probiotic EC-M17 to antimicrobials may induce changes in antimicrobials susceptibility, biofilm formation, growth rate, and relative pathogenicity. Therefore, as far as possible, the probiotic E. coli M17 should not be used in combination with antibiotics and further investigations are required to expand similar work on more probiotics in order to avoid resistance build-up which might be transmitted by horizontal transfer.

scholarly journals CnaA domains in bacterial pili are efficient dissipaters of large mechanical shocks

2016 ◽  
Vol 113 (9) ◽  
pp. 2490-2495 ◽  
Author(s):  
Daniel J. Echelman ◽  
Jorge Alegre-Cebollada ◽  
Carmen L. Badilla ◽  
Chungyu Chang ◽  
Hung Ton-That ◽  
...  
Keyword(s):  
Single Molecule ◽  
Pathogenic Bacteria ◽  
Mechanical Energy ◽  
Bacterial Attachment ◽  
Gram Positive ◽  
Covalent Bonds ◽  
Single Molecule Force Spectroscopy ◽  
Hydrophobic Collapse ◽  
Gram Positive Bacteria ◽  
Mechanical Shocks

Pathogenic bacteria adhere despite severe mechanical perturbations induced by the host, such as coughing. In Gram-positive bacteria, extracellular protein appendages termed pili are necessary for adherence under mechanical stress. However, little is known about the behavior of Gram-positive pili under force. Here, we demonstrate a mechanism by which Gram-positive pili are able to dissipate mechanical energy through mechanical unfolding and refolding of isopeptide bond-delimited polypeptide loops present in Ig-type CnaA domains. Using single-molecule force spectroscopy, we find that these loops of the pilus subunit SpaA of the SpaA-type pilus from Corynebacterium diphtheriae and FimA of the type 2 pilus from Actinomyces oris unfold and extend at forces that are the highest yet reported for globular proteins. Loop refolding is limited by the hydrophobic collapse of the polypeptide and occurs in milliseconds. Remarkably, both SpaA and FimA initially refold to mechanically weaker intermediates that recover strength with time or ligand binding. Based on the high force extensibility, CnaA-containing pili can dissipate ∼28-fold as much energy compared with their inextensible counterparts before reaching forces sufficient to cleave covalent bonds. We propose that efficient mechanical energy dissipation is key for sustained bacterial attachment against mechanical perturbations.

Bio-Inspired In Situ Fabrication of 11-Mercaptoundecanoic Acid Coating on Stainless Steel 304 for Corrosion Protection

2018 ◽  
Vol 913 ◽  
pp. 375-383
Author(s):  
Shuo Tian Sun ◽  
Yan Hua Lei ◽  
Tao Liu ◽  
Run Hua Fan ◽  
Shi Bin Sun
Keyword(s):  
Corrosion Protection ◽  
Photoelectron Spectroscopy ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Film Structure ◽  
Covalent Attachment ◽  
Water Contact ◽  
In Situ Fabrication ◽  
Corrosion Resistance Property

Bio-inspired in situ fabrication of 11-Mercaptoundecanoic Acid was proposed to prepare self-assembled coating of alkanethiolates on SS304 alloy. In this method, the SS304 was coated with a reactive biopolymer – Polydopamine (PDA) by dispersing them in a dopamine solution and mildly stirring at room temperature with subsequent covalent attachment of 11-Mercaptoundecanoic Acid molecules through the interaction between thiol groups and Polydopamine. The formation and surface structure of the coating were characterized by water contact angle measurement, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The electronic properties of such obtained functional film were studied by potentiodynamic polarization curve and EIS in 3.5% NaCl solution. Corrosion protection efficiency near 99 % was evaluated, and the excellent corrosion resistance property could be ascribed to the compact film structure and good seawater stability for modified SS304 surface, especially in limiting the infiltration of Cl-.

scholarly journals Covalently Bonded Ir(IV) on Conducted Blue TiO2 for Efficient Electrocatalytic Oxygen Evolution Reaction in Acid Media

Catalysts ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1176
Author(s):  
Chau T. K. Nguyen ◽  
Ngoc Quang Tran ◽  
Thi Anh Le ◽  
Hyoyoung Lee
Keyword(s):  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Acid Media ◽  
Covalent Bonds ◽  
Covalently Bonded ◽  
Tiny Amount ◽  
Primary Obstacle ◽  
Anode Electrode ◽  
Mass Activity ◽  
The Stability

The stability of anode electrode has been a primary obstacle for the oxygen evolution reaction (OER) in acid media. We design Ir-oxygen of hydroxyl-rich blue TiO2 through covalent bonds (Ir–O2–2Ti) and investigate the outcome of favored exposure of different amounts of covalent Ir–oxygen linked to the conductive blue TiO2 in the acidic OER. The Ir-oxygen-blue TiO2 nanoclusters show a strong synergy in terms of improved conductivity and tiny amount usage of Ir by using blue TiO2 supporter, and enhanced stability using covalent Ir-oxygen-linking (i.e., Ir oxide) in acid media, leading to high acidic OER performance with a current density of 10 mA cm−2 at an overpotential of 342 mV, which is much higher than that of IrO2 at 438 mV in 0.1 M HClO4 electrolyte. Notably, the Ir–O2–2Ti has a great mass activity of 1.38 A/mgIr at an overpotential 350 mV, which is almost 27 times higher than the mass activity of IrO2 at the same overpotential. Therefore, our work provides some insight into non-costly, highly enhanced, and stable electrocatalysts for the OER in acid media.

scholarly journals Extending Scaled-Interaction Adaptive-Partitioning QM/MM to Covalently Bonded Systems

2020 ◽  
Author(s):  
Zenghui Yang
Keyword(s):  
Charge Density ◽  
Computational Cost ◽  
Original Form ◽  
Time Step ◽  
Covalent Bonds ◽  
Simple Modification ◽  
Adaptive Partitioning ◽  
Covalently Bonded ◽  
Continuous Potential ◽  
Simple Molecules

Quantum mechanics/molecular mechanics (QM/MM) is the method of choice for atomistic simulations of large systems that can be partitioned into active and environmental regions. Adaptive-partitioning (AP) methods extend the applicability of QM/MM, allowing active zones to change during the simulation. AP methods achieve continuous potential energy surface (PES) by introducing buffer regions in which atoms have both QM and MM characters. Most of the existing AP-QM/MM methods require multiple QM calculations per time step, which can be expensive for systems with many atoms in buffer regions. Although one can lower the computational cost by grouping atoms into fragments, this may not be possible for all systems, especially for applications in covalent solids. The SISPA method [J. Chem. Theory Comput. 2017, 13, 2342] differs from other AP-QM/MM methods by only requiring one QM calculation per time step, but it has the flaw that the QM charge density and wavefunction near the buffer/MM boundary tend to those of isolated atoms/fragments. Besides, regular QM/MM methods for treating covalent bonds cut by the QM/MM boundary are incompatible with SISPA. Due to these flaws, SISPA in its original form cannot treat covalently bonded systems properly. In this work, I show that a simple modification to the SISPA method improves the treatment of covalently bonded systems. I also study the effect of correcting the charge density in SISPA by developing a density-corrected pre-scaled algorithm. I demonstrate the methods with simple molecules and bulk solids.

In vitro effects of silver nanoparticles on gills morphology of female Guppy ( Poecilia reticulate ) after a short‐term exposure

2020 ◽  
Vol 83 (12) ◽  
pp. 1552-1557 ◽  
Author(s):  
Reza Mohsenpour ◽  
Hamed Mousavi‐Sabet ◽  
Aliakbar Hedayati ◽  
Amir Rezaei ◽  
Ahmad Mohamadi Yalsuyi ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Short Term ◽  
Short Term Exposure ◽  
In Vitro Effects

scholarly journals Antimicrobial peptide coatings for hydroxyapatite: electrostatic and covalent attachment of antimicrobial peptides to surfaces

2017 ◽  
Vol 14 (126) ◽  
pp. 20160657 ◽  
Author(s):  
Leigh Townsend ◽  
Richard L. Williams ◽  
Olachi Anuforom ◽  
Matthew R. Berwick ◽  
Fenella Halstead ◽  
...  
Keyword(s):  
Antimicrobial Peptide ◽  
Cell Attachment ◽  
Bacterial Colonization ◽  
Covalent Attachment ◽  
Dual Approach ◽  
Covalently Bonded ◽  
Novel Method ◽  
Tissue Interface ◽  
Peptide Coatings ◽  
Implanted Devices

The interface between implanted devices and their host tissue is complex and is often optimized for maximal integration and cell adhesion. However, this also gives a surface suitable for bacterial colonization. We have developed a novel method of modifying the surface at the material–tissue interface with an antimicrobial peptide (AMP) coating to allow cell attachment while inhibiting bacterial colonization. The technology reported here is a dual AMP coating. The dual coating consists of AMPs covalently bonded to the hydroxyapatite surface, followed by deposition of electrostatically bound AMPs. The dual approach gives an efficacious coating which is stable for over 12 months and can prevent colonization of the surface by both Gram-positive and Gram-negative bacteria.

Assessment of DNA damage and molecular responses in Labeo rohita (Hamilton, 1822) following short-term exposure to silver nanoparticles

2016 ◽  
Vol 96 ◽  
pp. 122-132 ◽  
Author(s):  
Niti Sharma ◽  
Mohd Ashraf Rather ◽  
Malachy N.O. Ajima ◽  
P. Gireesh-Babu ◽  
Kundan Kumar ◽  
...  
Keyword(s):  
Dna Damage ◽  
Silver Nanoparticles ◽  
Labeo Rohita ◽  
Short Term ◽  
Molecular Responses ◽  
Short Term Exposure
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