oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2018 ( 1 )

2017 ( 1 )

2015 ( 52 )

2014 ( 63 )

Custom range...

Search Results: 1 - 10 of 1011 matches for " Webster TJ "
All listed articles are free for downloading (OA Articles)
Page 1 /1011
Display every page Item
Cytotoxicity of selenium nanoparticles in rat dermal fibroblasts
Ramos JF, Webster TJ
International Journal of Nanomedicine , 2012, DOI: http://dx.doi.org/10.2147/IJN.S33767
Abstract: otoxicity of selenium nanoparticles in rat dermal fibroblasts Original Research (2731) Total Article Views Authors: Ramos JF, Webster TJ Published Date July 2012 Volume 2012:7 Pages 3907 - 3914 DOI: http://dx.doi.org/10.2147/IJN.S33767 Received: 10 May 2012 Accepted: 20 June 2012 Published: 23 July 2012 Joseph F Ramos,1 Thomas J Webster2 1School of Engineering, Center of Biomedical Engineering, 2School of Engineering and Department of Orthopedics, Brown University, Providence, RI, USA Background: Ventilator-associated pneumonia is a deadly nosocomial infection caused by contaminated endotracheal tubes. It has been shown that polyvinyl chloride (PVC, the endotracheal tube substrate) coated with elemental selenium nanoparticles reduces bacterial adherence and proliferation on PVC by over 99%. However, it is not known if selenium nanoparticles elicit a cytotoxic effect in vitro. The purpose of this study was to investigate the cytotoxic effects of PVC coated with selenium nanoparticles on fibroblasts, which are mammalian cells central to endotracheal tube intubation. Methods: Different concentrations of selenium nanoparticles were precipitated onto the PVC surface by reduction of selenium salts using glutathione. Characterization of PVC coated with selenium nanoparticles was done by scanning electron microscopy, energy dispersive x-ray, and contact angle measurements. For the cytotoxicity experiments, fibroblasts were seeded at a density of 5000 cm2 onto PVC coated with three different concentrations of selenium nanoparticles (high, medium, low) and incubated for 4 hours (adhesion) as well as for 24 hours and 72 hours (proliferation). The half-maximal inhibitory concentration (IC50) value was determined after 72 hours using an ultrahigh concentration. MTT assays were used to assess cell viability at the indicated time points. Results: The three concentrations of selenium nanoparticles did not elicit a cytotoxic effect after 72 hours (P < 0.01, n = 3). It was found that the IC50 value was at the ultrahigh concentration of selenium nanoparticles. The nanoparticulate elemental selenium concentration previously shown to decrease the function of bacteria was shown not to cause a cytotoxic effect on fibroblasts in vitro. Conclusion: These findings demonstrate great selectivity between bacteria and healthy cells, and are a viable option for coating endotracheal tubes in order to prevent ventilator-associated pneumonia.
Antimicrobial applications of nanotechnology: methods and literature
Seil JT, Webster TJ
International Journal of Nanomedicine , 2012, DOI: http://dx.doi.org/10.2147/IJN.S24805
Abstract: ntimicrobial applications of nanotechnology: methods and literature Review (5690) Total Article Views Authors: Seil JT, Webster TJ Published Date June 2012 Volume 2012:7 Pages 2767 - 2781 DOI: http://dx.doi.org/10.2147/IJN.S24805 Received: 03 August 2011 Accepted: 31 August 2011 Published: 06 June 2012 Justin T Seil, Thomas J Webster Laboratory for Nanomedicine Research, School of Engineering, Brown University, Providence, RI, USA Abstract: The need for novel antibiotics comes from the relatively high incidence of bacterial infection and the growing resistance of bacteria to conventional antibiotics. Consequently, new methods for reducing bacteria activity (and associated infections) are badly needed. Nanotechnology, the use of materials with dimensions on the atomic or molecular scale, has become increasingly utilized for medical applications and is of great interest as an approach to killing or reducing the activity of numerous microorganisms. While some natural antibacterial materials, such as zinc and silver, possess greater antibacterial properties as particle size is reduced into the nanometer regime (due to the increased surface to volume ratio of a given mass of particles), the physical structure of a nanoparticle itself and the way in which it interacts with and penetrates into bacteria appears to also provide unique bactericidal mechanisms. A variety of techniques to evaluate bacteria viability, each with unique advantages and disadvantages, has been established and must be understood in order to determine the effectiveness of nanoparticles (diameter ≤100 nm) as antimicrobial agents. In addition to addressing those techniques, a review of select literature and a summary of bacteriostatic and bactericidal mechanisms are covered in this manuscript.
Spray deposition of live cells throughout the electrospinning process produces nanofibrous three-dimensional tissue scaffolds
Seil J, Webster TJ
International Journal of Nanomedicine , 2011, DOI: http://dx.doi.org/10.2147/IJN.S18803
Abstract: ay deposition of live cells throughout the electrospinning process produces nanofibrous three-dimensional tissue scaffolds Short Report (4312) Total Article Views Authors: Seil J, Webster TJ Published Date May 2011 Volume 2011:6 Pages 1095 - 1099 DOI: http://dx.doi.org/10.2147/IJN.S18803 Justin T Seil, Thomas J Webster Laboratories for Nanomedicine Research, School of Engineering, Brown University, Providence, RI, USA Abstract: Compared with traditional in-vitro cell culture materials, three-dimensional nanofibrous scaffolds provide a superior environment for promoting cell functions. Since nanofibrous scaffolds have nanometer pore sizes, cells are unable to penetrate on their own, so must be incorporated into the scaffold during fabrication to ensure proper cell distribution. In this study, biodegradable and cytocompatible poly(DL-lactide-co-glycolide) (PLGA) nanofibers were produced using an electrospinning process. As a model cell line, fibroblasts were periodically sprayed from a pump-action spray bottle onto the developing scaffold. The viability of cells before and after spraying, and also after incorporation into the scaffold, was compared. Results indicated that cell spraying and the scaffold fabrication process did not significantly reduce cell viability. These findings, thus, contribute to the understanding of how to produce more physiological relevant cell-seeded nanofibrous scaffolds, an important element for the future of nanotechnology and tissue engineering.
Selenium nanoparticles inhibit Staphylococcus aureus growth
Tran PA, Webster TJ
International Journal of Nanomedicine , 2011, DOI: http://dx.doi.org/10.2147/IJN.S21729
Abstract: ium nanoparticles inhibit Staphylococcus aureus growth Original Research (7130) Total Article Views Authors: Tran PA, Webster TJ Published Date July 2011 Volume 2011:6 Pages 1553 - 1558 DOI: http://dx.doi.org/10.2147/IJN.S21729 Phong A Tran1, Thomas J Webster2 1Physics Department, 2School of Engineering and Department of Orthopedics, Brown University, Providence, RI, USA Abstract: Staphylococcus aureus is a key bacterium commonly found in numerous infections. S. aureus infections are difficult to treat due to their biofilm formation and documented antibiotic resistance. While selenium has been used for a wide range of applications including anticancer applications, the effects of selenium nanoparticles on microorganisms remain largely unknown to date. The objective of this in vitro study was thus to examine the growth of S. aureus in the presence of selenium nanoparticles. Results of this study provided the first evidence of strongly inhibited growth of S. aureus in the presence of selenium nanoparticles after 3, 4, and 5 hours at 7.8, 15.5, and 31 μg/mL. The percentage of live bacteria also decreased in the presence of selenium nanoparticles. Therefore, this study suggests that selenium nanoparticles may be used to effectively prevent and treat S. aureus infections and thus should be further studied for such applications.
Reduced adhesion of Staphylococcus aureus to ZnO/PVC nanocomposites
Geilich BM, Webster TJ
International Journal of Nanomedicine , 2013, DOI: http://dx.doi.org/10.2147/IJN.S42010
Abstract: uced adhesion of Staphylococcus aureus to ZnO/PVC nanocomposites Original Research (23) Total Article Views Authors: Geilich BM, Webster TJ Published Date March 2013 Volume 2013:8 Pages 1177 - 1184 DOI: http://dx.doi.org/10.2147/IJN.S42010 Received: 23 December 2012 Accepted: 14 January 2013 Published: 21 March 2013 Benjamin M Geilich,1 Thomas J Webster2 1Program in Bioengineering, 2Department of Chemical Engineering, College of Engineering, Northeastern University, Boston, MA, USA Abstract: In hospitals and clinics worldwide, medical device surfaces have become a rapidly growing source of nosocomial infections. In particular, patients requiring mechanical ventilation (and, thus, intubation with an endotracheal tube) for extended lengths of time are faced with a high probability of contracting ventilator-associated pneumonia. Once inserted into the body, the endotracheal tube provides a surface to which bacteria can adhere and form a biofilm (a robust, sticky matrix that provides protection against the host immune system and antibiotic treatment). Adding to the severity of this problem is the spread of bacterial genetic tolerance to antibiotics, in part demonstrated by the recent and significant increase in the prevalence of methicillin-resistant Staphylococcus aureus. To combat these trends, different techniques in biomaterial design must be explored. Recent research has shown that nanomaterials (materials with at least one dimension less than 100 nm) may have the potential to prevent or disrupt bacterial processes that lead to infections. In this study, polyvinyl chloride (PVC) taken from a conventional endotracheal tube was embedded with varying concentrations of zinc oxide (ZnO) nanoparticles. S. aureus biofilms were then grown on these nanocomposite surfaces during a 24-hour culture. Following this, biofilms were removed from the surfaces and the number of colony forming units present was assessed. Bacterial proliferation on the samples embedded with the highest concentration of ZnO nanoparticles was 87% less when compared to the control, indicating that this technique is effective at reducing biofilm formation on PVC surfaces without the use of antibiotics.
Anodizing color coded anodized Ti6Al4V medical devices for increasing bone cell functions
Ross AP, Webster TJ
International Journal of Nanomedicine , 2013, DOI: http://dx.doi.org/10.2147/IJN.S36203
Abstract: nodizing color coded anodized Ti6Al4V medical devices for increasing bone cell functions Original Research (879) Total Article Views Authors: Ross AP, Webster TJ Published Date January 2013 Volume 2013:8 Pages 109 - 117 DOI: http://dx.doi.org/10.2147/IJN.S36203 Received: 21 July 2012 Accepted: 17 September 2012 Published: 04 January 2013 Alexandra P Ross, Thomas J Webster School of Engineering and Department of Orthopedics, Brown University, Providence, RI, USA Abstract: Current titanium-based implants are often anodized in sulfuric acid (H2SO4) for color coding purposes. However, a crucial parameter in selecting the material for an orthopedic implant is the degree to which it will integrate into the surrounding bone. Loosening at the bone–implant interface can cause catastrophic failure when motion occurs between the implant and the surrounding bone. Recently, a different anodization process using hydrofluoric acid has been shown to increase bone growth on commercially pure titanium and titanium alloys through the creation of nanotubes. The objective of this study was to compare, for the first time, the influence of anodizing a titanium alloy medical device in sulfuric acid for color coding purposes, as is done in the orthopedic implant industry, followed by anodizing the device in hydrofluoric acid to implement nanotubes. Specifically, Ti6Al4V model implant samples were anodized first with sulfuric acid to create color-coding features, and then with hydrofluoric acid to implement surface features to enhance osteoblast functions. The material surfaces were characterized by visual inspection, scanning electron microscopy, contact angle measurements, and energy dispersive spectroscopy. Human osteoblasts were seeded onto the samples for a series of time points and were measured for adhesion and proliferation. After 1 and 2 weeks, the levels of alkaline phosphatase activity and calcium deposition were measured to assess the long-term differentiation of osteoblasts into the calcium depositing cells. The results showed that anodizing in hydrofluoric acid after anodizing in sulfuric acid partially retains color coding and creates unique surface features to increase osteoblast adhesion, proliferation, alkaline phosphatase activity, and calcium deposition. In this manner, this study provides a viable method to anodize an already color coded, anodized titanium alloy to potentially increase bone growth for numerous implant applications.
Reducing infections through nanotechnology and nanoparticles
Taylor E, Webster TJ
International Journal of Nanomedicine , 2011, DOI: http://dx.doi.org/10.2147/IJN.S22021
Abstract: ucing infections through nanotechnology and nanoparticles Review (9437) Total Article Views Authors: Taylor E, Webster TJ Published Date July 2011 Volume 2011:6 Pages 1463 - 1473 DOI: http://dx.doi.org/10.2147/IJN.S22021 Erik Taylor1, Thomas J Webster1,2 1School of Engineering, 2Department of Orthopedics, Brown University, Providence, RI, USA Abstract: The expansion of bacterial antibiotic resistance is a growing problem today. When medical devices are inserted into the body, it becomes especially difficult for the body to clear robustly adherent antibiotic-resistant biofilm infections. In addition, concerns about the spread of bacterial genetic tolerance to antibiotics, such as that found in multiple drug-resistant Staphylococcus aureus (MRSA), have significantly increased of late. As a growing direction in biomaterial design, nanomaterials (materials with at least one dimension less than 100 nm) may potentially prevent bacterial functions that lead to infections. As a first step in this direction, various nanoparticles have been explored for improving bacteria and biofilm penetration, generating reactive oxygen species, and killing bacteria, potentially providing a novel method for fighting infections that is nondrug related. This review article will first examine in detail the mechanisms and applications of some of these nanoparticles, then follow with some recent material designs utilizing nanotechnology that are centered on fighting medical device infections.
Short communication: inhibiting biofilm formation on paper towels through the use of selenium nanoparticles coatings
Wang Q, Webster TJ
International Journal of Nanomedicine , 2013, DOI: http://dx.doi.org/10.2147/IJN.S38777
Abstract: rt communication: inhibiting biofilm formation on paper towels through the use of selenium nanoparticles coatings Original Research (829) Total Article Views Authors: Wang Q, Webster TJ Published Date January 2013 Volume 2013:8 Pages 407 - 411 DOI: http://dx.doi.org/10.2147/IJN.S38777 Received: 03 October 2012 Accepted: 15 October 2012 Published: 23 January 2013 Qi Wang,1 Thomas J Webster2 1Bioengineering Program, 2Department of Chemical Engineering, College of Engineering, Northeastern University, Boston, MA, USA Abstract: Bacterial infections are commonly found on paper towels and other paper products, leading to the potential spread of bacteria and consequent health concerns. The objective of this in vitro study was to introduce antibacterial properties to standard paper towel surfaces by coating them with selenium nanoparticles. Scanning electron microscopy was used to measure the size and distribution of the selenium coatings on the paper towels. Atomic force microscopy was used to measure the surface roughness of paper towels before and after they were coated with selenium nanoparticles. The amount of selenium precipitated on the paper towels was measured by atomic absorption spectroscopy. In vitro bacterial studies with Staphylococcus aureus were conducted to assess the effectiveness of the selenium coating at inhibiting bacterial growth. Results showed that the selenium nanoparticles coated on the paper towel surface were well distributed with semispherical geometries about 50 nm in diameter. Most importantly, the selenium nanoparticle-coated paper towels inhibited S. aureus growth by 90% after 24 and 72 hours compared with the uncoated paper towels. Thus, the study showed that nanoparticle selenium-coated paper towels may lead to an increased eradication of bacteria in a wider range of clinical environments and in the food industry, thus improving human health.
Anodizing color coded anodized Ti6Al4V medical devices for increasing bone cell functions
Ross AP,Webster TJ
International Journal of Nanomedicine , 2013,
Abstract: Alexandra P Ross, Thomas J WebsterSchool of Engineering and Department of Orthopedics, Brown University, Providence, RI, USAAbstract: Current titanium-based implants are often anodized in sulfuric acid (H2SO4) for color coding purposes. However, a crucial parameter in selecting the material for an orthopedic implant is the degree to which it will integrate into the surrounding bone. Loosening at the bone–implant interface can cause catastrophic failure when motion occurs between the implant and the surrounding bone. Recently, a different anodization process using hydrofluoric acid has been shown to increase bone growth on commercially pure titanium and titanium alloys through the creation of nanotubes. The objective of this study was to compare, for the first time, the influence of anodizing a titanium alloy medical device in sulfuric acid for color coding purposes, as is done in the orthopedic implant industry, followed by anodizing the device in hydrofluoric acid to implement nanotubes. Specifically, Ti6Al4V model implant samples were anodized first with sulfuric acid to create color-coding features, and then with hydrofluoric acid to implement surface features to enhance osteoblast functions. The material surfaces were characterized by visual inspection, scanning electron microscopy, contact angle measurements, and energy dispersive spectroscopy. Human osteoblasts were seeded onto the samples for a series of time points and were measured for adhesion and proliferation. After 1 and 2 weeks, the levels of alkaline phosphatase activity and calcium deposition were measured to assess the long-term differentiation of osteoblasts into the calcium depositing cells. The results showed that anodizing in hydrofluoric acid after anodizing in sulfuric acid partially retains color coding and creates unique surface features to increase osteoblast adhesion, proliferation, alkaline phosphatase activity, and calcium deposition. In this manner, this study provides a viable method to anodize an already color coded, anodized titanium alloy to potentially increase bone growth for numerous implant applications.Keywords: nanotechnology, titanium, osteoblasts, anodization
Reduced adhesion of Staphylococcus aureus to ZnO/PVC nanocomposites
Geilich BM,Webster TJ
International Journal of Nanomedicine , 2013,
Abstract: Benjamin M Geilich,1 Thomas J Webster21Program in Bioengineering, 2Department of Chemical Engineering, College of Engineering, Northeastern University, Boston, MA, USAAbstract: In hospitals and clinics worldwide, medical device surfaces have become a rapidly growing source of nosocomial infections. In particular, patients requiring mechanical ventilation (and, thus, intubation with an endotracheal tube) for extended lengths of time are faced with a high probability of contracting ventilator-associated pneumonia. Once inserted into the body, the endotracheal tube provides a surface to which bacteria can adhere and form a biofilm (a robust, sticky matrix that provides protection against the host immune system and antibiotic treatment). Adding to the severity of this problem is the spread of bacterial genetic tolerance to antibiotics, in part demonstrated by the recent and significant increase in the prevalence of methicillin-resistant Staphylococcus aureus. To combat these trends, different techniques in biomaterial design must be explored. Recent research has shown that nanomaterials (materials with at least one dimension less than 100 nm) may have the potential to prevent or disrupt bacterial processes that lead to infections. In this study, polyvinyl chloride (PVC) taken from a conventional endotracheal tube was embedded with varying concentrations of zinc oxide (ZnO) nanoparticles. S. aureus biofilms were then grown on these nanocomposite surfaces during a 24-hour culture. Following this, biofilms were removed from the surfaces and the number of colony forming units present was assessed. Bacterial proliferation on the samples embedded with the highest concentration of ZnO nanoparticles was 87% less when compared to the control, indicating that this technique is effective at reducing biofilm formation on PVC surfaces without the use of antibiotics.Keywords: nanomaterials, endotracheal tube, biofilm, zinc oxide, nanoparticles, Staphylococcus aureus
Page 1 /1011
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.