The Experts below are selected from a list of 23724 Experts worldwide ranked by ideXlab platform
Jolanta A Watson - One of the best experts on this subject based on the ideXlab platform.
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a gecko skin micro nano structure a low adhesion superhydrophobic anti wetting self cleaning biocompatible Antibacterial Surface
Acta Biomaterialia, 2015Co-Authors: Gregory S Watson, David W Green, Lin Schwarzkopf, Xin Li, Bronwen W Cribb, Sverre Myhra, Jolanta A WatsonAbstract:Geckos, and specifically their feet, have attracted significant attention in recent times with the focus centred around their remarkable adhesional properties. Little attention however has been dedicated to the other remaining regions of the lizard body. In this paper we present preliminary investigations into a number of notable interfacial properties of the gecko skin focusing on solid and aqueous interactions. We show that the skin of the box-patterned gecko (Lucasium sp.) consists of dome shaped scales arranged in a hexagonal patterning. The scales comprise of spinules (hairs), from several hundred nanometres to several microns in length, with a sub-micron spacing and a small radius of curvature typically from 10 to 20 nm. This micro and nano structure of the skin exhibited ultralow adhesion with contaminating particles. The topography also provides a superhydrophobic, anti-wetting barrier which can self clean by the action of low velocity rolling or impacting droplets of various size ranges from microns to several millimetres. Water droplets which are sufficiently small (10-100 μm) can easily access valleys between the scales for efficient self-cleaning and due to their dimensions can self-propel off the Surface enhancing their mobility and cleaning effect. In addition, we demonstrate that the gecko skin has an Antibacterial action where Gram-negative bacteria (Porphyromonas gingivalis) are killed when exposed to the Surface however eukaryotic cell compatibility (with human stem cells) is demonstrated. The multifunctional features of the gecko skin provide a potential natural template for man-made applications where specific control of liquid, solid and biological contacts is required.
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A gecko skin micro/nano structure – A low adhesion, superhydrophobic, anti-wetting, self-cleaning, biocompatible, Antibacterial Surface
Acta Biomaterialia, 2015Co-Authors: Gregory S Watson, David W Green, Lin Schwarzkopf, Bronwen W Cribb, Sverre Myhra, Jolanta A WatsonAbstract:Geckos, and specifically their feet, have attracted significant attention in recent times with the focus centred around their remarkable adhesional properties. Little attention however has been dedicated to the other remaining regions of the lizard body. In this paper we present preliminary investigations into a number of notable interfacial properties of the gecko skin focusing on solid and aqueous interactions. We show that the skin of the box-patterned gecko (Lucasium sp.) consists of dome shaped scales arranged in a hexagonal patterning. The scales comprise of spinules (hairs), from several hundred nanometres to several microns in length, with a sub-micron spacing and a small radius of curvature typically from 10 to 20 nm. This micro and nano structure of the skin exhibited ultralow adhesion with contaminating particles. The topography also provides a superhydrophobic, anti-wetting barrier which can self clean by the action of low velocity rolling or impacting droplets of various size ranges from microns to several millimetres. Water droplets which are sufficiently small (10-100 μm) can easily access valleys between the scales for efficient self-cleaning and due to their dimensions can self-propel off the Surface enhancing their mobility and cleaning effect. In addition, we demonstrate that the gecko skin has an Antibacterial action where Gram-negative bacteria (Porphyromonas gingivalis) are killed when exposed to the Surface however eukaryotic cell compatibility (with human stem cells) is demonstrated. The multifunctional features of the gecko skin provide a potential natural template for man-made applications where specific control of liquid, solid and biological contacts is required.
Paul K. Chu - One of the best experts on this subject based on the ideXlab platform.
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Antibacterial Surface Design of Titanium-Based Biomaterials for Enhanced Bacteria-Killing and Cell-Assisting Functions Against Periprosthetic Joint Infection
ACS Applied Materials and Interfaces, 2016Co-Authors: Jiaxing Wang, Geyong Guo, Qiaojie Wang, Shi Qian, Jin Tang, Xuanyong Liu, Jinhua Li, Hao Shen, Xianlong Zhang, Paul K. ChuAbstract:Periprosthetic joint infection (PJI) is one of the formidable and recalcitrant complications after orthopedic surgery and inhibiting biofilm formation on the implant Surface is considered crucial to prophylaxis of PJI. However, it has recently been demonstrated that free-floating biofilm-like aggregates in the local body fluid and bacterial colonization on the implant and peri-implant tissues can coexist and are involved in the pathogenesis of PJI. An effective Surface with both contact-killing and release-killing antimicrobial capabilities can potentially abate these concerns and minimize PJI caused by adherent/planktonic bacteria. Herein, Ag nanoparticles (NPs) are embedded in titania (TiO2) nanotubes by anodic oxidation and plasma immersion ion implantation (PIII) to form a contact-killing Surface. Vancomycin is then incorporated into the nanotubes by vacuum extraction and lyophilization to produce the release-killing effect. A novel clinical PJI model system involving both in vitro and in vivo use of methicillin-resistant Staphylococcus aureus (MRSA) ST239 is established to systematically evaluate the Antibacterial properties of the hybrid Surface against planktonic and sessile bacteria. The vancomycin-loaded and Ag-implanted TiO2 nanotubular Surface exhibits excellent antimicrobial and anti-biofilm effects against planktonic/adherent bacteria without appreciable silver ion release. The fibroblasts/bacteria co-cultures reveal that the Surface can help fibroblasts to combat bacteria. We first utilize the nano-architecture of implant Surface as a bridge between the inorganic bactericide (Ag NPs) and organic Antibacterial agent (vancomycin) to achieve total victory in the battle of PJI. The combination of contact-killing and release-killing together with cell-assisting function also provides a novel and effective strategy to mitigate bacterial infection and biofilm formation on biomaterials and has large potential in orthopedic applications.
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Plasma-Modified Biomaterials for Self-Antimicrobial Applications
ACS Applied Materials & Interfaces, 2011Co-Authors: Xiangmei Liu, Amy Yeung, Kelvin W.k. Yeung, Richard Y. T. Kao, Paul K. ChuAbstract:The Surface compatibility and Antibacterial properties of biomaterials are crucial to tissue engineering and other medical applications, and plasma-assisted technologies have been employed to enhance these characteristics with good success. Herein, we describe and review the recent developments made by our interdisciplinary team on self-antimicrobial biomaterials with emphasis on plasma-based Surface modification. Our results indicate that a self-Antibacterial Surface can be produced on various types of materials including polymers, metals, and ceramics by plasma treatment. Surface characteristics such as roughness, microstructure, chemistry, electronegativity, free energy, hydrophilicity, and interfacial physiochemistry are important factors and can be tailored by using the appropriate plasma-assisted processing parameters. In particular, mechanistic studies reveal that the interfacial physiochemical processes, biocidal agents, and Surface free energy are predominantly responsible for the Antibacterial e...
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Antibacterial copper containing titanium nitride films produced by dual magnetron sputtering
Surface & Coatings Technology, 2007Co-Authors: Xiubo Tian, Zeming Wang, Shiqin Yang, Zhengwei Luo, Paul K. ChuAbstract:There is an increasing interest in reducing bacterial harmfulness in recent years. Copper-containing titanium nitride films were fabricated on commercial stainless steel using hybrid processes combining dual magnetron sputtering. The objective of this work is to obtain Antibacterial Surface properties through copper doping for consumer products such as household hardware. In the fabrication process, a titanium target was sputtered using a radio-frequency power supply for easy monitoring of the film color. Copper was also sputtered using a DC power supply. In order to optimize the Surface properties, multi-layer films were deposited and the relative amount of copper in the films was modulated by the ratio of the deposition time of different targets. The deposited films exhibit superior corrosion resistance and the corrosion current of the treated sample is reduced to about one-sixth of that of the untreated one. The pin-on-disk results show that the treated samples possess low friction coefficients and the wear tracks are observed to be narrow and smooth. The copper-containing films are very effective in killing the bacteria Escherichia coli. A longer TiN deposition time may lead to a more superior Antibacterial capability in addition to enhanced corrosion resistance and wear resistance.
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antimicrobial properties of copper plasma modified polyethylene
Polymer, 2006Co-Authors: Yihe Zhang, Wei Zhang, Jun Zhao, Qing Yan, Paul K. ChuAbstract:Abstract Copper plasma immersion ion implantation is utilized to produce an Antibacterial Surface on polyethylene. XPS analysis of the plasma-treated materials reveals that a relatively large amount of copper, about 11% relative to carbon, is implanted into the near Surface region. At the same time, about 3% copper is found to be also deposited on the Surface. The implanted copper is observed to have the zero valence state indicating that the implanted Cu does not bind chemically with the atoms in the polymer. On the other hand, the copper atoms close to the Surface are found to have the divalent state due to Surface oxidation. Formation of C C bonds is also observed due to dehydrogenation following copper plasma implantation. Based on the results of atomic force microscopy and contact angle measurements, the Surface hydrophilicity and roughness are not significantly altered. Our Antibacterial experiments indicate that the copper implanted polyethylene exhibits excellent Antibacterial effects against Escherichia coli and Staphylococcus aureus , and the effectiveness is 96.2% and 86.1%, respectively.
Gregory S Watson - One of the best experts on this subject based on the ideXlab platform.
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a gecko skin micro nano structure a low adhesion superhydrophobic anti wetting self cleaning biocompatible Antibacterial Surface
Acta Biomaterialia, 2015Co-Authors: Gregory S Watson, David W Green, Lin Schwarzkopf, Xin Li, Bronwen W Cribb, Sverre Myhra, Jolanta A WatsonAbstract:Geckos, and specifically their feet, have attracted significant attention in recent times with the focus centred around their remarkable adhesional properties. Little attention however has been dedicated to the other remaining regions of the lizard body. In this paper we present preliminary investigations into a number of notable interfacial properties of the gecko skin focusing on solid and aqueous interactions. We show that the skin of the box-patterned gecko (Lucasium sp.) consists of dome shaped scales arranged in a hexagonal patterning. The scales comprise of spinules (hairs), from several hundred nanometres to several microns in length, with a sub-micron spacing and a small radius of curvature typically from 10 to 20 nm. This micro and nano structure of the skin exhibited ultralow adhesion with contaminating particles. The topography also provides a superhydrophobic, anti-wetting barrier which can self clean by the action of low velocity rolling or impacting droplets of various size ranges from microns to several millimetres. Water droplets which are sufficiently small (10-100 μm) can easily access valleys between the scales for efficient self-cleaning and due to their dimensions can self-propel off the Surface enhancing their mobility and cleaning effect. In addition, we demonstrate that the gecko skin has an Antibacterial action where Gram-negative bacteria (Porphyromonas gingivalis) are killed when exposed to the Surface however eukaryotic cell compatibility (with human stem cells) is demonstrated. The multifunctional features of the gecko skin provide a potential natural template for man-made applications where specific control of liquid, solid and biological contacts is required.
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A gecko skin micro/nano structure – A low adhesion, superhydrophobic, anti-wetting, self-cleaning, biocompatible, Antibacterial Surface
Acta Biomaterialia, 2015Co-Authors: Gregory S Watson, David W Green, Lin Schwarzkopf, Bronwen W Cribb, Sverre Myhra, Jolanta A WatsonAbstract:Geckos, and specifically their feet, have attracted significant attention in recent times with the focus centred around their remarkable adhesional properties. Little attention however has been dedicated to the other remaining regions of the lizard body. In this paper we present preliminary investigations into a number of notable interfacial properties of the gecko skin focusing on solid and aqueous interactions. We show that the skin of the box-patterned gecko (Lucasium sp.) consists of dome shaped scales arranged in a hexagonal patterning. The scales comprise of spinules (hairs), from several hundred nanometres to several microns in length, with a sub-micron spacing and a small radius of curvature typically from 10 to 20 nm. This micro and nano structure of the skin exhibited ultralow adhesion with contaminating particles. The topography also provides a superhydrophobic, anti-wetting barrier which can self clean by the action of low velocity rolling or impacting droplets of various size ranges from microns to several millimetres. Water droplets which are sufficiently small (10-100 μm) can easily access valleys between the scales for efficient self-cleaning and due to their dimensions can self-propel off the Surface enhancing their mobility and cleaning effect. In addition, we demonstrate that the gecko skin has an Antibacterial action where Gram-negative bacteria (Porphyromonas gingivalis) are killed when exposed to the Surface however eukaryotic cell compatibility (with human stem cells) is demonstrated. The multifunctional features of the gecko skin provide a potential natural template for man-made applications where specific control of liquid, solid and biological contacts is required.
Rohan A. Shirwaiker - One of the best experts on this subject based on the ideXlab platform.
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Interdigitated silver-polymer-based Antibacterial Surface system activated by oligodynamic iontophoresis – An empirical characterization study
Biomedical Microdevices, 2014Co-Authors: Rohan A. Shirwaiker, Richard A. Wysk, Subhashinie Kariyawasam, Hector Carrion, Robert C. Voigt, Harriet Black NembhardAbstract:There is a pressing need to control the occurrences of nosocomial infections due to their detrimental effects on patient well-being and the rising treatment costs. To prevent the contact transmission of such infections via health-critical Surfaces, a prophylactic Surface system that consists of an interdigitated array of oppositely charged silver electrodes with polymer separations and utilizes oligodynamic iontophoresis has been recently developed. This paper presents a systematic study that empirically characterizes the effects of the Surface system parameters on its Antibacterial efficacy, and validates the system’s effectiveness. In the first part of the study, a fractional factorial design of experiments (DOE) was conducted to identify the statistically significant system parameters. The data were used to develop a first-order response Surface model to predict the system’s Antibacterial efficacy based on the input parameters. In the second part of the study, the effectiveness of the Surface system was validated by evaluating it against four bacterial species responsible for several nosocomial infections – Staphylococcus aureus , Escherichia coli , Pseudomonas aeruginosa , and Enterococcus faecalis – alongside non-Antibacterial polymer (acrylic) control Surfaces. The system demonstrated statistically significant efficacy against all four bacteria. The results indicate that given a constant total effective Surface area, the system designed with micro-scale features (minimum feature width: 20 μm) and activated by 15 μA direct current will provide the most effective Antibacterial prophylaxis.
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Biocompatibility analysis of an electrically-activated silver-based Antibacterial Surface system for medical device applications
Journal of Materials Science: Materials in Medicine, 2013Co-Authors: Meghan E. Samberg, Nancy A. Monteiro-riviere, Paul E. Orndorff, Rohan A. ShirwaikerAbstract:The costs associated with the treatment of medical device and surgical site infections are a major cause of concern in the global healthcare system. To prevent transmission of such infections, a prophylactic Surface system that provides protracted release of Antibacterial silver ions using low intensity direct electric current (LIDC; 28 μA system current at 6 V) activation has been recently developed. To ensure the safety for future in vivo studies and potential clinical applications, this study assessed the biocompatibility of the LIDC-activated interdigitated silver electrodes-based Surface system; in vitro toxicity to human epidermal keratinocytes, human dermal fibroblasts, and normal human osteoblasts, and Antibacterial efficacy against Staphylococcus aureus and Escherichia coli was evaluated. The study concluded that the technological applications of the Surface system for medical devices and surgical tools, which contact human tissues for less than 1.5 h, are expected to be self-sterilizing without causing toxicity in vivo.
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Micro-scale fabrication and characterization of a silver-polymer-based electrically activated Antibacterial Surface.
Biofabrication, 2011Co-Authors: Rohan A. Shirwaiker, Richard A. Wysk, Subhashinie Kariyawasam, Hector Carrion, Robert C. VoigtAbstract:This paper reports the fabrication methodology and characterization results for an electrically activated silver-polymer-based Antibacterial Surface with primary applications in preventing indirect contact transmission of infections. The Surface consists of a micro-scale grating pattern of alternate silver electrodes and SU-8 partitions with a minimum feature size of 20 µm, and activated by an external voltage. In this study, prototype coupons (15 mm × 15 mm) of the Antibacterial Surface were fabricated on silicon substrates using two sets of lithographies, and analyzed for their physical characteristics using microscopy and Surface profilometry. The prototypes were also electrically analyzed to determine their current–voltage characteristics, and hence silver ion (Ag+) release concentrations. Finally, they were tested for their Antibacterial efficacy against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) using a newly engineered microbiological testing procedure. The Antibacterial efficacy testing results show significant reductions in the number of viable organisms of both the species after 45 min of testing with 15 µA system current. Due to the growing incidences of hospital-acquired infections and rising treatment costs, study and application of such alternative Antibacterial systems in critical touch-contact and work Surfaces (e.g., door push plates, countertops, medical instrument trays) for healthcare environments has become essential.
Robert C. Voigt - One of the best experts on this subject based on the ideXlab platform.
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Interdigitated silver-polymer-based Antibacterial Surface system activated by oligodynamic iontophoresis – An empirical characterization study
Biomedical Microdevices, 2014Co-Authors: Rohan A. Shirwaiker, Richard A. Wysk, Subhashinie Kariyawasam, Hector Carrion, Robert C. Voigt, Harriet Black NembhardAbstract:There is a pressing need to control the occurrences of nosocomial infections due to their detrimental effects on patient well-being and the rising treatment costs. To prevent the contact transmission of such infections via health-critical Surfaces, a prophylactic Surface system that consists of an interdigitated array of oppositely charged silver electrodes with polymer separations and utilizes oligodynamic iontophoresis has been recently developed. This paper presents a systematic study that empirically characterizes the effects of the Surface system parameters on its Antibacterial efficacy, and validates the system’s effectiveness. In the first part of the study, a fractional factorial design of experiments (DOE) was conducted to identify the statistically significant system parameters. The data were used to develop a first-order response Surface model to predict the system’s Antibacterial efficacy based on the input parameters. In the second part of the study, the effectiveness of the Surface system was validated by evaluating it against four bacterial species responsible for several nosocomial infections – Staphylococcus aureus , Escherichia coli , Pseudomonas aeruginosa , and Enterococcus faecalis – alongside non-Antibacterial polymer (acrylic) control Surfaces. The system demonstrated statistically significant efficacy against all four bacteria. The results indicate that given a constant total effective Surface area, the system designed with micro-scale features (minimum feature width: 20 μm) and activated by 15 μA direct current will provide the most effective Antibacterial prophylaxis.
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Micro-scale fabrication and characterization of a silver-polymer-based electrically activated Antibacterial Surface.
Biofabrication, 2011Co-Authors: Rohan A. Shirwaiker, Richard A. Wysk, Subhashinie Kariyawasam, Hector Carrion, Robert C. VoigtAbstract:This paper reports the fabrication methodology and characterization results for an electrically activated silver-polymer-based Antibacterial Surface with primary applications in preventing indirect contact transmission of infections. The Surface consists of a micro-scale grating pattern of alternate silver electrodes and SU-8 partitions with a minimum feature size of 20 µm, and activated by an external voltage. In this study, prototype coupons (15 mm × 15 mm) of the Antibacterial Surface were fabricated on silicon substrates using two sets of lithographies, and analyzed for their physical characteristics using microscopy and Surface profilometry. The prototypes were also electrically analyzed to determine their current–voltage characteristics, and hence silver ion (Ag+) release concentrations. Finally, they were tested for their Antibacterial efficacy against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) using a newly engineered microbiological testing procedure. The Antibacterial efficacy testing results show significant reductions in the number of viable organisms of both the species after 45 min of testing with 15 µA system current. Due to the growing incidences of hospital-acquired infections and rising treatment costs, study and application of such alternative Antibacterial systems in critical touch-contact and work Surfaces (e.g., door push plates, countertops, medical instrument trays) for healthcare environments has become essential.