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Bacterial adhesion to the surface can quickly lead to the development of biofilms, which can create a variety of economic and health issues. In the marine industry, Biofouling causes sailing resistance, resulting in higher fuel consumption and waste emissions for boats, ships, and submarines. Metals such as titanium and its alloys along with stainless steel are commonly used in orthopedic implants and the most common complications seen after the implantation are bacterial infections acquired through invasive and post-operative medical procedures. This type of infection damages the bone and surrounding tissues. Separating a biofilm from an implant surface is time-consuming because even minor biofilm residues left on the implant surface might cause the infection to reappear. Implant replacement or long-term antibiotic therapy are usually suggested in such circumstances, which is not optimal for individuals with co-morbid conditions. In the case of long-term use of antibiotics, antibiotic resistance is a serious issue. As a result, several techniques aimed at lowering the risk of bacterial infections in bio-implants are critical. Surface textures on a micro scale can help in the fight against Biofouling by increasing antibacterial properties, preventing bacterial adhesion, or killing or inactivating adherent microorganisms and creating an inapt environment for biofilm formation. As a result, the capacity to generate passive antibacterial surfaces on components has far-reaching consequences in practically every industry. In this study, micro-textures were generated on the surfaces of titanium (Grade 5), aluminum, and stainless steel. The topographical characteristics of the textured surfaces were studied, and a comparative study of wettability between textured and non-textured surfaces was conducted. S. aureus and E. coli, being the most common infection-causing bacteria in implants and were used to investigate the antibacterial properties. The results show that the textured surface lowers bacterial adhesion and growth up to 91.57% in comparison to the non-textured samples for E. coli and 51.40% for S. aureus, which can be related to the surface topography and the presence of peaks and troughs, which also contribute to the surface's Hydrophilicity. [ABSTRACT FROM AUTHOR]

In recent years, the growing problem of antibiotic resistance has highlighted the need for antibacterial materials to prevent the development of infections. Different types of tests exist to certify the antibacterial properties of materials. Variations in results can occur due to the unique requirements of each test technique. The antibacterial test result may be influenced, in particular, by the distinct modes of action of leaching and non‐leaching compounds. Using antibacterial materials prepared by the dispersion of an amphiphilic cationic synthetic copolymer in a polyurethane matrix, the influence of the reaction medium and the contact time on the results obtained by two well‐established tests: ISO 22196 and CERTIKA is investigated. This shows that the kinetics of killing is bacteria dependent and depending on the test conditions (concentration of salt, time of contact, or media), contradictory results could be obtained. Moreover, the influence of the ionic strength (called salt effect) in both free solution and antibacterial surface is highlighted. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM), widely used to fabricate medical devices, is applicable for antibacterial surface protection. Silver, transferred from tool electrode or powder suspended in the dielectric to the modified layer during the EDM process, significantly enhanced antibacterial properties of the modified surface. However, bacterial resistance to silver, which was widespread in clinical, still posed challenges for the modified surfaces containing silver. Zinc, owing to its strong antibacterial effects and no challenge related to Zn-resistant bacteria hitherto reported in clinical, was therefore used as tool electrode material to modify Ti6Al4V surfaces during the EDM process. Discharge energies up to 170 µJ with different polarities were applied in the EDM milling process using deionized water-based dielectric fluid. Results show that discharge energy and polarity play a vital role in chemical composition and roughness of the modified surfaces as well as material removal rate and tool wear rate. The surfaces containing zinc contents up to 28 % can be generated. The use of a low energy generates zinc-rich surfaces with less micro-cracks. The EDM process using zinc tool electrode shows a promising potential for antibacterial surface modification of medical devices. [ABSTRACT FROM AUTHOR]

This study aims to assess the antibacterial activity of boric acid ester derived from boron mines, which is utilised as an active component in the paint industry. Multiple product variations were obtained by adding boric acid ester to the base, referred to as the reference sample, known as silk matte paint, and used as an interior paint with active substance concentrations ranging from 0.005% to 0.6%. Escherichia coli (ATCC10536) bacteria were inoculated at 78000 cfu cm−2 into samples with 0.005- 0.075% active substance, and at 24000 cfu cm−2 into samples containing 0.15- 0.6% of the active substance, and the reduction rates were determined by a mathematical equation via multivariate linear regression analysis, relating Escherichia coli reduction percentages, surface energy values, and pH measurements, including the power percentages and gloss values for the reference sample. The highest level of antibacterial effect was observed in the sample containing 0.075% active substance. [ABSTRACT FROM AUTHOR]

The medical device market is a high-growth sector expected to sustain an annual growth rate of over 5%, even in developed countries. Daily, numerous patients have medical devices implanted or inserted within their bodies. While medical devices have significantly improved patient outcomes, as foreign objects, their wider use can lead to an increase in device-related infections, thereby imposing a burden on healthcare systems. Multiple materials with significant societal impact have evolved over time: the 19th century was the age of iron, the 20th century was dominated by silicon, and the 21st century is often referred to as the era of carbon. In particular, the development of nanocarbon materials and their potential applications in medicine are being explored, although the scope of these applications remains limited. Technological innovations in carbon materials are remarkable, and their application in medicine is expected to advance greatly. For example, diamond-like carbon (DLC) has garnered considerable attention for the development of antimicrobial surfaces. Both DLC itself and its derivatives have been reported to exhibit anti-microbial properties. This review discusses the current state of DLC-based antimicrobial surface development. [ABSTRACT FROM AUTHOR]

The spread of diseases caused by bacterial adhesion and immobilization in public places constitutes a serious threat to public health. Prevention of bacteria spread by the construction of an antibacterial surface takes precedence over post-infection treatment. Herein, we demonstrate an effective antibacterial surface with strong wear resistance by constructing cationic engineered nanodiamonds (C-NDs). The C-NDs with positive surface potentials interact effectively with bacteria through electrostatic interactions, where the C-NDs act on the phospholipid bilayer and lead to bacterial membrane collapse and rupture through hydrogen bonding and residual surface oxygen-containing reactive groups. In this case, bactericidal rate of 99.99% and bacterial biofilm inhibition rate of more than 80% can be achieved with the C-NDs concentration of 1 mg/mL. In addition, the C-NDs show outstanding antibacterial stability, retaining over 87% of the antibacterial effect after stimulation by adverse environments of heat, acid, and external abrasion. Therefore, an antibacterial surface with high wear resistance obtained by integrating C-NDs with commercial plastics has been demonstrated. The antibacterial surface with a mass fraction of 1 wt.% C-NDs improved abrasion resistance by 3981 times, with 99% killing of adherent bacteria. This work provides an effective strategy for highly efficient antibacterial wear-resistant surface, showing great practical applications in public health environments. [ABSTRACT FROM AUTHOR]

Bacterial‐related infections can be hazardous for human health and the surrounding environment. Traditional antibiotic‐based treatments for these infections are increasingly ineffective due to the emergence of antibiotic‐resistant bacteria. Antimicrobial peptide mimics have emerged as promising replacements owing to their potency against bacteria and lack of susceptibility to generate resistant cells. Thus, we synthesized a random copolymer, consisting of aminopropyl methacrylamide and benzyl methacrylamide (AB polymer) by random co‐polymerization that mimics host–defense antimicrobial peptides. For its use as a coating, the AB polymer is drop‐casted onto a cleaned glass substrate and tested for its antibacterial activity toward Escherichia coli and Staphylococcus aureus, wherein almost 99% of antibacterial activity was observed within 5 min. The prepared coating also possessed excellent longevity characteristics of up to 5 weeks. The AB polymer is also able to inhibit biofilm formation as well as disrupt a mature biofilm and can also be employed as an antibacterial wipe for cleaning bacterial contaminated surfaces. Mechanism study through SEM analysis showed that the AB polymer ruptures the bilayer membrane of both bacterial strains, thereby leading to pore formation causing cell death. Cell viability study depicted that 71% of the A549 lung carcinoma epithelial cells are viable compared to 80% on bare glass substrate. Thus, the synthesized AB polymer may be used in a variety of antibacterial applications directly in the form of solution (wipes) or forming a coating (drop casted/spray coated) for battling bacterial colonization. [ABSTRACT FROM AUTHOR]

Mechano-bactericidal nanopillars represent a class of antibacterial surfaces that rely on nanoscale topographical features to inflict damage on attached bacteria. A potential application for mechano-bactericidal nanopillars is their use as self-cleaning antibacterial coatings for surfaces that are exposed to inadvertent splashes or cough droplets containing infectious bacteria. In this work, we prepared two types of zinc oxide nanopillars: nanopillars with an average width of 194 nm and an average spacing of 163 nm (referred to as low-surface-density nanopillars) and nanopillars with an average width of 88 nm and an average spacing of 91 nm (referred to as high-surface-density nanopillars). To assess their antibacterial capabilities, we deposited small aqueous droplets containing bioluminescent Pseudomonas aeruginosa onto the nanopillars and monitored the loss of the bioluminescence signal to quantify acute bacterial inactivation in real time. To investigate possible recovery of bacterial viability after acute inactivation, the nanopillars were submerged in nutrient-rich media and incubated for another 24 h, while the bioluminescence signal was monitored. Combining the results from bioluminescence monitoring with scanning electron microscopy, optical density measurements, and plate counting of colony-forming units after the recovery period, we found that nanopillars with an average width of 194 nm and an average spacing of 163 nm were indeed mechano-bactericidal and efficacy was dependent on the bacterial concentration within the droplets. Nanopillars with an average width of 88 nm and an average spacing of 91 nm were ineffective as bactericidal surfaces regardless of the bacterial concentration. This work further supports the use-case of mechano-bactericidal nanopillars as antibacterial coatings for dry surfaces and demonstrates bioluminescence monitoring as a promising tool to complement existing assessment techniques for mechano-bactericidal nanopillars as well as other antibacterial coatings. [ABSTRACT FROM AUTHOR]

The alternative antibacterial treatment photothermal therapy (PTT) significantly affects oral microbiota inactivation. In this work, graphene with photothermal properties was coated on a zirconia surface using atmospheric pressure plasma, and then the antibacterial properties against oral bacteria were evaluated. For the graphene oxide coating on the zirconia specimens, an atmospheric pressure plasma generator (PGS-300, Expantech, Suwon, Republic of Korea) was used, and an Ar/CH4 gas mixture was coated on a zirconia specimen at a power of 240 W and a rate of 10 L/min. In the physiological property test, the surface properties were evaluated by measuring the surface shape of the zirconia specimen coated with graphene oxide, as well as the chemical composition and contact angle of the surface. In the biological experiment, the degree of adhesion of Streptococcus mutans (S. mutans) and Porphyromonas gingivalis (P. gingivalis) was determined by crystal violet assay and live/dead staining. All statistical analyzes were performed using SPSS 21.0 (SPSS Inc., Chicago, IL, USA). The group in which the zirconia specimen coated with graphene oxide was irradiated with near-infrared rays demonstrated a significant reduction in the adhesion of S. mutans and P. gingivalis compared with the group not irradiated. The oral microbiota inactivation was reduced by the photothermal effect on the zirconia coated with graphene oxide, exhibiting photothermal properties. [ABSTRACT FROM AUTHOR]

This work aimed to enhance the surface properties of common food packaging materials (PVC, PS, PET, PVDC) by applying a TiO2 nano thin film coating. Physical and chemical analyses confirmed a well-defined anatase phase film. PET showed the highest antibacterial activity, followed by PVDC, PS, and PVC. After 60 min of UV-A irradiation, E. coli elimination rates were 99.85% (PET), 97.14% (PVDC), 96.5% (PS), and 85.91% (PVC). Similarly, for S. Typhimurium, the respective rates were 97.8% (PET), 83.71% (PVDC), 74.79% (PS), and 68.94% (PVC). Complete eradication of both strains occurred within 120 min (E. coli) and 180 min (S. Typhimurium). Durability testing revealed PET's mass loss of 97 mg/kg after 15 cycles, while PVC had the lowest value of 7 mg/kg. These findings demonstrate that TiO2 thin film-coated substrates effectively inhibit bacteria growth, extending food product shelf life. [ABSTRACT FROM AUTHOR]

Additive manufacturing has opened the door to patient‐tailored orthopedic implants, which can significantly minimize implant failures associated with prosthesis‐to‐bone mismatch. Success of an implant also depends on the choice of implant materials, effective osseointegration, implant quality, and the mechanical properties together with its capability to limit infection due to bacterial contamination. Herein, nanospikes are created on 3D‐printed titanium‐alloyed implant surfaces, which can kill bacteria to minimize any implant‐associated infections. For the first time, orthopedic implants with a fracture to the proximal phalanx are fabricated using selective laser melting (SLM) followed by a heat‐treatment step and the hydrothermal process. It is showed in the results that by optimizing SLM parameters, dimensionally consistent parts can be produced and tensile properties of the 3D‐printed implants can be significantly improved via a simple cyclic heat‐treatment process compared to the traditionally manufactured implants. Nanospikes similar to those present on dragonfly wings fabricated on 3D‐printed implants surface are able to kill above 90% of adhering bacteria by rupturing the membranes upon contact. These results indicate that fabrication of patient‐specific 3D‐printed implants with inherent bactericidal properties has the potential to eliminate postsurgical infections and possible implant failures. [ABSTRACT FROM AUTHOR]

The globalization of the market, as well as the increasing world population, which require a higher demand for food products, pose a great challenge to ensure food safety and prevent food loss and waste. In this sense, active materials with antibacterial properties are an important alternative in the prolongation of shelf life and ensuring food safety. In this work, the ability of copper(II) hydroxy nitrate (CuHS) to obtain antibacterial films based on low density polyethylene (LDPE) and polylactic acid (PLA), was evaluated. The thermal properties of the composites, evaluated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), showed that the concentrations of added CuHS do not particularly change these characteristics with respect to the neat polymer matrix films. The mechanical properties, determined using dynamic mechanical analysis (DMTA), indicate a small increase in the brittleness of the material in PLA-based composites. The antibacterial properties against Listeria monocytogenes and Salmonella enterica were evaluated using a surface contact test, and a bacterial reduction of at least 8 to 9 logarithmic units for the composites with 0.3% CuHS, both in LDPE and PLA and against both bacteria, were achieved. The reusability of the composite films after their first use demonstrated a higher stability against Listeria monocytogenes. The migration and cytotoxicity of the composites loaded with 0.3% CuHS was evaluated, demonstrating the safety of these materials, which reinforces their potential use in food packaging applications. [ABSTRACT FROM AUTHOR]

Recent years have seen much attention being given to self-assembly of dipeptide-based structures, especially to self-regulation of dipeptide structures with different amino acid sequences. In this study we investigated the effects of varying solvent environments on the self-assembly of glycine-histidine (Gly-His) dipeptide structures. First we determined the morphological properties of Gly-His films formed in different solvent environments with scanning electron microscopy and then structural properties with Fourier-transform infrared (FTIR) spectroscopy. In addition, we studied the effects of Gly-His films on silver nanoparticle (AgNP) formation and the antioxidant and cytotoxic properties of AgNPs obtained in this way. We also, assessed antibacterial activities of Gly-His films against Gram-negative Escherichia coli and Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus. Silver nanoparticle-decorated Gly-His films were not significantly cytotoxic at concentrations below 2 mg/mL but had antibacterial activity. We therefore believe that AgNP-decorated Gly-His films at concentrations below 2 mg/mL can be used safely against bacteria.

Cyclic N-halamines are highly antimicrobial, very stable, and not susceptible to bacterial resistance. A polysiloxane delivery vehicle was synthesized to deliver cyclic imide N-halamine onto cellulose via a benign and universal procedure that does not require a harmful solvent or chemical bonding. In brief, Knoevenagel condensation between barbituric acid and 4-hydroxybenzaldehyde furnished 5-(4-hydroxybenzylidene)pyrimidine-2,4,6-trione, whose phenolic O−H was subsequently reacted with the Si−H of poly(methylhydrosiloxane) (PMHS) via silane alcoholysis. The product of silane alcoholysis was interpenetrated into cellulose in supercritical CO2 (scCO2) at 50 °C, to form a continuous modification layer. The thickness of the modification layer positively correlated with interpenetration pressure in the experimental range of 10 to 28 MPa and reached a maximum value of 76.5 nm, which demonstrates the ability for tunable delivery, to control the loading of the imide N−H bond originating from barbituric acid unit. The imide N−H bonds on cellulose with the thickest modifier were then chlorinated into N−Cl counterparts using tert-butyl hypochlorite, to exert a powerful biocidability, providing ~7 log reductions of both S. aureus and E. coli in 20 min. The stability and rechargeability of the biocidability were both very promising, suggesting that the polysiloxane modifier has a satisfactory chemical structure and interlocks firmly with cellulose via scCO2 interpenetration. [ABSTRACT FROM AUTHOR]

To prevent implant-associated infections, surface modifications need to be developed that prevent bacterial colonisation and biofilm formation. In the present study, titanium surfaces were processed by nanosecond-pulsed laser ablation to generate a variety of different structures (anatase, rutile, Osteon, as well as Osteon additionally coated with silver and clove nanoparticles). Analysis of adhesion and biofilm formation of the oral pioneer bacterium Streptococcus oralis could demonstrate antibacterial properties of anatase surfaces. For clinical translation, the effect should be enhanced by further adaption and combined with the osseointegrative Osteon structure

[Display omitted] • Magnetron-sputtered DLC:Cu films effectively release Cu compounds in aqueous media. • Oxygen plasma etching oxidises the Cu and prolongs the metal compound release. • The DLC matrix remains intact despite the different plasma and immersion exposures. • Effective against corona and herpes viruses and E.coli and E.faecalis bacteria. • The Cu release in aqueous media defines the virucidal efficacy of the films. Copper compound-rich films and coatings are effective against widespread viruses and bacteria. Even though the killing mechanisms are still debated, it is agreed that the metal ion, nanoparticle release, and surface effects are of paramount importance to the antiviral and antibacterial efficacy of the surfaces. In this work we have investigated the behavior of the reactive magnetron sputtered nanocomposite diamond-like carbon thin films with copper nanoparticles (DLC:Cu). The films were etched employing oxygen plasma and/or exposed to ultra-pure water, aiming to investigate the differences of the Cu release in the medium and changes in film morphology. The presence of metallic copper and Cu 2 O phases was confirmed by multiple analytical methods. Pristine films were more effective in the Cu release reaching up to 1.3 mg/L/cm2 concentration. Plasma processing resulted in the oxidation of the films which released less Cu, but after exposure to water, their average roughness increased more, up to 5.5 nm. Pristine and O 2 plasma processed DLC:Cu films were effective against both model coronavirus and herpesvirus after 1-hour contact time and reached virus reductions of up to 2.23 and 1.63 log 10 , respectively. Pristine DLC:Cu films were more effective than plasma-processed ones against herpesvirus, while less expressed difference was found for coronavirus. The virucidal efficacy over up to 24 h exposures in the aqueous medium was validated. A bactericidal study confirmed that pristine DLC:Cu films were effective against gram-negative E. coli and gram-positive E. faecalis bacteria. After 3 h, 100 % antibacterial efficiency (ABE) was obtained for E. coli and 99.97 % for E. faecalis. After 8 h and longer exposures, 100 % ABE was reached. The half-life inactivation of viruses was 8.10–11.08 min and for E. faecalis 15.1–72.2 min. [ABSTRACT FROM AUTHOR]

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Antibacterial surfaces are surfaces that can resist bacteria, relying on the nature of the material itself. It is significant for safe food and water, human health, and industrial equipment. Biofilm is the main form of bacterial contamination on the material surface. Preventing the formation of biofilm is an efficient way to develop antibacterial surfaces. The strategy for constructing the antibacterial surface is divided into bacteria repelling and bacteria killing based on the formation of the biofilm. Material surface wettability, adhesion, and steric hindrance determine bacteria repelling performance. Bacteria should be killed by surface chemistry or physical structures when they are attached to a material surface irreversibly. Killing approaches are usually in the light of the cell membrane of bacteria. This review summarizes the fabrication methods and applications of antibacterial surfaces from the view of the treatment of the material surfaces. We also present several crucial points for developing long-term stability, no drug resistance, broad-spectrum, and even programable antibacterial surfaces. [ABSTRACT FROM AUTHOR]

Bacteria in the external environment inevitably invade the wound and subsequently colonize the wound surface during surgery and biomedical operations, which slows down the process of wound healing and tissue repair; this poses a significant threat to human health. Therefore, the development of an intelligent antibacterial surface has become the focus of research in the field of antimicrobial strategies, which has important social and economic significance. Here, we present a simple approach of producing an ionic interaction-driven anionic activation substratum which is then functionalized with cationic molecules through coulombic interactional immobilization. The switchable multifunctional antibacterial surface can decrease bacterial attachment and inactivate the attached microorganisms, thus overcoming the conventional challenge for antibacterial surfaces. Briefly, poly (3-sulfopropyl methacrylate potassium salt) (PSPMA) brushes were constructed by surface-initiated atom transfer radical polymerization on silicon or cotton fabric substrates, and a positive-charged component, namely lysozyme (LYZ), hexadecyl trimethyl ammonium bromide (CTAB) or chitosan (CS), was loaded on negative-charged sulfonate groups through electrostatic interactions. The resultant brush-grafted surfaces exhibited more than ∼95.5% bactericidal efficacy and ∼92.8% release rate after the introduction of an adequate amount of contra-ions (1.0 M; Na+ & Cl−) against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus , thus achieving a regenerated surface through the cyclic process of "assembly-dissociation". Smart cotton fabric (Fabric-PSPMA/LYZ and Fabric-PSPMA/CS) surfaces were constructed, which were found to promote wound epidermal tissue regeneration with a higher efficiency after 7-day in vivo studies. This ionic interaction-driven method used in the present work is simple and can reversibly renew antibacterial surfaces, which will help in the wider utilization of switchable antibacterial materials with a more ecologic and economic significance. Smart antibacterial surfaces with renewable characteristics have attracted considerable interests over the past few years. Here, we used ionic interaction-driven force to manipulate dynamic conformational changes in PSPMA surface brushes, accompanied by highly switchable bacteria killing and bacteria releasing behaviors. Different cationic molecules were also designed for assembly/dissociation on the PSPMA-modified surfaces, and the essential parameters, including chemical structures, molecular weight, and cationic charge density, were investigated. With the refined structural combinations and the balance of bacteria killing/bacteria releasing behaviors, smart cotton fabrics (e.g., Fabric-PSPMA/lysozyme and Fabric-PSPMA/chitosan) were designed that could promote wound healing and tissue repair. These results contribute to the fundamental understanding of a switchable cationic-anionic pair design and the corresponding practical, renewable, highly antibacterial fabric. [Display omitted] [ABSTRACT FROM AUTHOR]

Initial microbial attachment on surfaces is the first step in bacteria contamination and direct intervention in the early adhesion stage by constructing an antibacterial coating is an effective strategy to prevent the attachment and proliferation of bacteria. Herein, a storable polyphenol-based coating is designed and fabricated by self-assembling the cationic template and ionic ligand. The materials containing microparticles with sticky properties inherited from tannic can be deposited on various surfaces by a simple redispersion-immersion process. The functional ligands on the outer layer of the coating can kill bacteria by combining chemical damages produced by tannic as well as mechanical disruption caused by the micro-nano topography as reflected by the elevated Young's modulus and differentiated stiffness of the bacterial membrane. The results reveal a simple method to prepare polyphenol-based antibacterial coatings and enrich our understanding of the combined use of chemical and mechanical interventions to enhance the antibacterial activity. [ABSTRACT FROM AUTHOR]

Abstract Antibacterial surfaces coated with nanomaterials, including silver nanoparticles, are considered effective alternative antimicrobial agents that can be used instead of antibiotics and chemical agents. However, reports of the potential toxicity of these materials raise questions about the safety of their use in biomedical applications. The objective of this research was to reduce the human cell cytotoxicity of silver nanoparticle-coated polyurethane foils by complexing silver nanoparticles with graphene oxide. The antimicrobial activity of nanoplatforms coated with silver nanoparticles, graphene oxide and the composite of silver nanoparticles and graphene oxide was assessed with Salmonella enteritidis. Cytotoxicity was analysed by an analysis of the viability and morphology of human fibroblasts, human umbilical vein endothelial cells (HUVECs) and chicken embryo chorioallantoic membrane. Additionally, the synthesis level of inflammatory proteins was examined for fibroblasts cultured on different nanoplatforms. The nanoplatform coated with the silver nanoparticles and graphene oxide composite showed strongest antibacterial properties, although nanoplatforms coated with only silver nanoparticles or graphene oxide also resulted in decreased S. enteritidis growth. Furthermore, a nanoplatform coated with silver nanoparticles and graphene oxide composite showed limited immunological stimulation and significantly reduced cytotoxicity towards fibroblasts, HUVECs and chicken embryo chorioallantoic membrane in comparison to the nanoplatform coated only with silver nanoparticles, due to the higher stability of the nanomaterials in the nanocomposite.

The globalization of the market and the increase of the global population that requires a higher demand of food products superimposes a big challenge to ensure food safety. In this sense, a common strategy to extend the shelf life and save life of food products is by avoiding bacterial contamination. For this, the development of antibacterial contact surfaces is an urgent need to fulfil the above-mentioned strategy. In this work, the role of MXene (Ti3C2Tx) in providing antibacterial contact surfaces was studied through the creation of composite films from polylactic acid (PLA), as the chosen polymeric matrix. The developed PLA/MXene films maintained the thermal and mechanical properties of PLA and also presented the attractive antibacterial properties of MXene. The composites’ behaviour against two representative foodborne bacteria was studied: Listeria mono-cytogenes and Salmonella enterica (representing Gram-positive and Gram-negative bacteria, respectively). The composites prevented bacterial growth, and in the case of Listeria only 0.5 wt.% of MXene was necessary to reach 99.9999% bactericidal activity (six log reductions), while against Salmonella, 5 wt.% was necessary to achieve 99.999% bactericidal activity (five log reductions). Cy-totoxicity tests with fHDF/TER166 cell line showed that none of the obtained materials were cytotoxic. These results make MXene particles promising candidates for their use as additives into a polymeric matrix, useful to fabricate antibacterial contact surfaces that could prove useful for the food packaging industry.

[Display omitted] Hydrophobic micro-porous membrane such as polyvinylidene fluoride (PVDF) with excellent thermal-/chemical-stability and low surface energy has received extensive attention in industrial water treatment and sustainable energy conversion. However, undesirable contaminants caused by inevitable proteins or microorganisms adhesion may lead to a rapid loss of separation efficiency, which significantly deteriorate their porous structures and eventually limit their practical performance. Herein, we present a scalable approach for fabricating comb-like copolymer modified PVDF membranes (PVDF-PN@AgNPs) that prevent bacteria from proliferating on the surface and temperature-controlled release of adhered contaminants. Comb-like structured copolymers were imparted to a polydopamine (PDA)-treated PVDF membrane by Michael addition reaction, which enabled a covalent binding of comb-like structured copolymers to the membrane. Such unique structural design of grafted copolymer, containing hydrophilic side chain and temperature-responsive chain backbone, stably prevents bacteria adhesion and provides reversible surface wettability. Therefore, the resultant membranes were evaluated to prevent bacterial adhesion, high touch-killing efficiency and temperature-controlled contaminants release (~99% of protein and ~75% of bacteria). Moreover, with the collapse and stretch of grafted copolymer chain backbone, the synthetic membrane further reversibly adjusted inner micro-porous structure and surface wettability, which eventually helped to achieve variable water fluid transport efficiency. This study not only provides a feasible structural design for stably coping with the challenging of antifouling and subsequent contamination adhesion of PVDF membrane, but also potentially answers the significant gap between lab research advances and practical application, particularly in the industrial membrane field. [ABSTRACT FROM AUTHOR]

Surface contamination is a major concern in the design, fabrication, and application of biomaterials. In this work, a series of new adenine derivatives were synthesized in a three‐step method with the goal of protecting the functional materials against microbial adhesion. Initially, 9‐(chloroalkyl)‐9H‐purin‐6‐amine compounds were synthesized from adenine. Then, these compounds were reacted with potassium thiocyanate or potassium selenocyanate. In the last step, adenine derivatives incorporating a tetrazole ring were synthesized via the cycloaddition of sodium azide with thiocyano or selenocyano derivatives. The antimicrobial activity of the compounds was evaluated by using the minimal inhibitory concentration method. Furthermore, the effect of the compounds on pBR322 plasmid DNA was studied using gel electrophoretic mobility measurements. The antimicrobial assay showed that some of the synthesized compounds exerted vigorous antibacterial and antifungal activities. Further experiments indicated that seleno‐adenine derivatives have higher antimicrobial and DNA effect than other derivatives. The surfaces activated by the adenine derivative demonstrated antibacterial activity resisting bacterial attachment in order to remove dead bacteria from the surface. All results showed that some of these adenine derivatives have an antibacterial activity and the potential for further applications, for example as a smart surface coating that prevents bacterial adhesion to biomaterials. [ABSTRACT FROM AUTHOR]

Abstract Background Due to the increased emergence of antimicrobial resistance, alternatives to minimize the usage of antibiotics become attractive solutions. Biophysical manipulation of material surface topography to prevent bacterial adhesion is one promising approach. To this end, it is essential to understand the relationship between surface topographical features and bactericidal properties in order to develop antibacterial surfaces. Results In this work a systematic study of topographical effects on bactericidal activity of nanostructured surfaces is presented. Nanostructured Ormostamp polymer surfaces are fabricated by nano-replication technology using nanoporous templates resulting in 80-nm diameter nanopillars. Six Ormostamp surfaces with nanopillar arrays of various nanopillar densities and heights are obtained by modifying the nanoporous template. The surface roughness ranges from 3.1 to 39.1 nm for the different pillar area parameters. A Gram-positive bacterium, Staphylococcus aureus, is used as the model bacterial strain. An average pillar density at ~ 40 pillars μm−2 with surface roughness of 39.1 nm possesses the highest bactericidal efficiency being close to 100% compared with 20% of the flat control samples. High density structures at ~ 70 pillars μm−2 and low density structures at

La inclusión del cobre como material antibacteriano en la arquitectura sanitaria ayuda a resolver la gran paradoja que existe en los servicios asistenciales; entrar a servicios de salud para sanarse de una enfermedad puntual y adquirir enfermedades de riesgo de muerte. Esta investigación demuestra la eficacia del cobre en formato laminar en vez de sólido, haciendo mediciones de con luminometría, abriendo un camino factible para el cobre como revestimiento antibacteriano y dotando de su propiedad antibacteriana superficial a costos reducidos, sin necesidad de cambios de mobiliario ni obras Abstract The inclusion of copper as an antibacterial material in health architecture helps to solve the great paradox that exists in healthcare services; enter health services to heal from a specific illness and acquire life-threatening diseases. This research demonstrates the effectiveness of copper in laminar format instead of solid, making measurements of ATP with luminometry, opening a feasible way for copper as an antibacterial coating and endowing its superficial antibacterial property at reduced costs, without the need for furniture changes or works.

Ag (silver)-based bioceramic coatings were fabricated on AZ31 Mg alloy by combining the MAO (micro-arc oxidation) and PVD (physical vapor deposition) methods. As a first step, AZ31 Mg surfaces were coated using MAO using a solution consisting of sodium silicate and potassium hydroxide. As a second step, an Ag layer was accumulated on the MAO surfaces using the PVD method. The XRD patterns thus obtained demonstrated the presences of Mg (magnesium), Si (silicon), M2SiO4 (forsterite) and MgO (periclase) on the Ag-deposited MAO surfaces. The elemental or compound structures of Ag were not detected due to the homogeneous distribution of a trace amount of Ag on the surfaces. Both coatings' surfaces were porous due to the existence of discharge channels. All elements were found to be uniformly distributed across the entirety of the surfaces. The Ag-deposited MAO surfaces were found to have hydrophobic properties with respect to plain MAO surfaces. Newly formed layers consisted of Ca 15 (SiO 4) 6 (PO 4) 2 (calcium silicate phosphate), Ca 3 (PO 4) 2 (tuite) and Ca 10 (PO 4) 6 (OH) 2 (hydroxyapatite) as produced on plain MAO and Ag-deposited MAO surfaces by immersion in SBF (simulated body fluid); these layers were more homogeneous on Ag-deposited MAO coatings than ones on plain MAO. Also, for E. coli (Escherichia coli) and S. aureus (Staphylococcus aureus) bacteria, the numbers of active bacterial colonies on Ag-deposited MAO surfaces were significantly reduced with respect to plain MAO surfaces. • Ag-based MgO/Mg 2 SiO 4 bioceramic coatings on AZ31 Mg were uniformly produced by MAO and TE techniques. • The Ag-based MAO surfaces presented superhydrophobic properties compared to the MAO surfaces. • The apatite layer on the Ag-based MAO surfaces was more homogeneous than one on the MAO surfaces. • In vitro bioactivity of the Ag-based MAO coatings was improved compared to the MAO coatings. • Active bacteria colonies on Ag-based MAO surfaces was reduced compared to the MAO coatings. [ABSTRACT FROM AUTHOR]

Microbial contamination of biomedical surfaces is an important clinical challenge, driving the development of new antibacterial materials. Nanoprotrusions on the wing surface of some insects have intrinsic antibacterial and antifouling properties, which inspires fabrication of biomimetic nanopatterns on medical devices. Herein, we report a broad-spectrum bactericidal surface consisting of graphene nanospikes synthesized by plasma-enhanced chemical vapor deposition. Similar coatings have been reported before, but the killing mechanism and main parameters for efficiency of such coatings have not been clarified. We investigated the correlation of anti-biofilm efficiency of graphene nanospikes to their major physicochemical parameters. While height and thickness of nanospikes did not directly correlate with bactericidal effects, edge/defect density showed linear correlation with lethality for both Gram-negative and Gram-positive bacteria. We further demonstrated that the killing mechanism is synergistic, depending on physical rupture of bacterial membranes as well as considerable oxidative damage to the cells. Of note, for the first time, we quantify the level of oxidative stress induced by graphene nanospikes in two bacterial species using genetically encoded biosensors. Our work provides a fundamental understanding of the impact of various parameters of graphene nanostructures on the bactericidal efficiency, enabling rational design of graphene-based bactericidal surfaces. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract This work describes the morphology, corrosion resistance, and antibacterial performance of copper coating deposited onto carbon steel by cold gas spray (CGS). Cross-sectional images of the coating showed a dense microstructure, with porosity lower than 1%. XRD analysis revealed no oxides or phases different to pure copper. The results of electrochemical tests demonstrated the efficient barrier properties and the compact microstructure of the coating, which protected the substrate against corrosion in chloride solution for >1000 h. The copper coating was effective as an antimicrobial agent for inhibiting the growth of Staphylococcus aureus , with bacterial growth being completely inhibited after 10 min of direct contact between the bacteria and the coating surface. Graphical abstract Unlabelled Image Highlights • Copper powders were sprayed onto carbon steel using cold gas spray (CGS). • Copper coatings are dense with low porosity and high adhesion. • Coating resisted to corrosion in 3.5 wt% NaCl solution for ~1100 h. • CGS coatings showed an antibacterial rate of the 100% after 10 min of test. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • N-halamine and pyridinium were incorporated onto magnetic sub-microparticles. • The combination of N-halamine and pyridinium showed synergism. • The synergism provided boosted biocidability than single functionality counterparts. • The biocidability was stable and the rechargability of N-halamine was promising. Abstract Dual biocidal groups of N-halamine and pyridinium were used to modify surface of magnetic sub-microparticles to exert enhanced synergistic antibacterial capacity. Magnetic silica Fe 3 O 4 sub-microparticles (SMPs) were synthesized and then encapsulated with interpenetrating polymer network (IPN) of polystyrene (PS) and poly(acrylic acid) (PAA). The carboxylic acid groups of PAA were used as surface reactive sites to bond with amino groups of 4-aminopyridine through amidation reaction. N-halamine/pyridinium-derivatized magnetic sub-microparticles were sequentially produced by quaternization of the pyridine to pyridinium with 1-chlorohexane and chlorination of amide N–H to N-halamine with NaClO. The synthetic steps and products were characterized with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray photoelectron spectrocsopy (XPS). The N-halamine/pyridinium-derivatized SMPs with dual biocidal functionalities showed faster deactivation abilities against both Escherichia coli and Staphylococcus aureus compared with their counterparts that contained only N-halamine or pyridinium, and exhibited promising stability toward repeated washing and long-term storage. The designed SMPs in this study offer potential and ideal candidates for sterilization application due to multiple advantages including improved synergistic biocidal ability, high surface area, and easy recyclability. [ABSTRACT FROM AUTHOR]

In the present work, the effect of graphene oxide (GO) nanosheets on the antibacterial activity of CuO nanowire arrays under visible light irradiation is shown. A combined thermal oxidation/electrophoretic deposition technique was employed to prepare three-dimensional networks of graphene oxide nanosheets hybridized with vertically aligned CuO nanowires. With the help of standard antibacterial assays and X-ray photoelectron spectroscopy, it is shown that the light-activated antibacterial response of the hybrid material against gram-negative Escherichia coli is significantly improved as the oxide functional groups of the GO nanosheets are reduced. In order to explore the physicochemical mechanism behind this behavior, ab-initio simulations based on density functional theory were performed and the effect of surface functional groups and hybridization were elucidated. Supported by the experiments, a three-step photo-antibacterial based mechanism is suggested: (i) injection of an electron from CuO into rGO, (ii) localization of the excess electron on rGO functional groups, and (iii) release of reactive oxygen species lethal to bacteria. Activation of new photoactive and physical mechanisms in the hybrid system makes rGO-modified CuO nanowire coatings as promising nanostructure devices for antimicrobial applications in particular for dry environments. [ABSTRACT FROM AUTHOR]

Despite the fact that numerous infection-resistant surfaces have been developed to prevent bacterial colonization and biofilm formation, developing a stable, highly antibacterial and easily produced surface remains a technical challenge. As a crucial structural component of biofilm, extracellular DNA (eDNA) can facilitate initial bacterial adhesion, subsequent development, and final maturation. Inspired by the mechanistic pathways of natural enzymes (deoxyribonuclease), here we report a novel antibacterial surface by employing cerium (Ce(IV)) ion to mimic the DNA-cleavage ability of natural enzymes. In this process, the coordination chemistry of plant polyphenols and metal ions was exploited to create an in situ metal-phenolic film on substrate surfaces. Tannic acid (TA) works as an essential scaffold and Ce(IV) ion acts as both a cross-linker and a destructor of eDNA. The Ce(IV)-TA modified surface exhibited highly enhanced bacteria repellency and biofilm inhibition when compared with those of pristine or Fe(III)-TA modified samples. Moreover, the easily produced coatings showed high stability under physiological conditions and had nontoxicity to cells for prolonged periods of time. This as-prepared DNA-cleavage surface presents versatile and promising performances to combat biomaterial-associated infections. [ABSTRACT FROM AUTHOR]

Abstract: Herein, ene‐functionalized dopamine is first coated onto a polyether sulfone membrane surface to introduce double bonds as anchoring sites for hydrogel film. Then, a hydrogel film is synthesized and simultaneously attached onto the membrane via photoinduced crosslinking copolymerization of N‐isopropylacrylamide (NIPAAm) and methacryloxyethyltrimethyl ammonium chloride. The thickness of the hydrogel film can be well‐controlled ranging from the nanometer to micrometer scales, which can retain the permeability of the membrane. Water contact angle and swelling tests demonstrate that the modified membrane shows thermoresponsive surface wettability. The quaternary ammonium salts in the hydrogel film can kill the attached bacteria efficiently and the dead bacteria can be detached by reducing the temperature below the lower critical solution temperature of poly(NIPAAm). The modified membrane also shows improved hemocompatibility, confirmed by prolonged clotting time and low hemolysis ratio. Hence, the designed thermoresponsive antibacterial hydrogel film with enhanced hemocompatibility has great potential to be applied in biomedical areas. [ABSTRACT FROM AUTHOR]

[Display omitted] • A dynamic self-polishing and self-renewing antibacterial surface was developed. • The functionalized surface has good biocompatibility, enzymatic biodegradable properties and excellent bactericidal properties. • This strategy provides a promising and new route to design and fabricate multifunctional surfaces with long-term antibacterial activity for biomaterials and implantable devices. To meet the development of multifunctional surfaces with long-term antibacterial activity for biomaterials and implantable devices, herein, a novel self-polishing antibacterial surface was developed. The functionalized surface was prepared by first surface-initiated ring-opening grafting polymerization (SI-ROP) of a cyclic carbonate monomer 4′-(fluorosulfonyl)benzyl-5-methyl-2-oxo-1,3-dioxane-5-carboxylate (FMC) containing a sulfonyl fluoride group in the side chain onto the material surface and then by a "sulfur(IV)-fluorine" exchange (SuFEx) postclick modification reaction to link the imidazolium salt ionic liquid to the polyFMC (PFMC) brush. In vitro experimental results showed that the functionalized surface has good biocompatibility, enzymatic biodegradable properties and excellent bactericidal properties, which can effectively kill E. coli (∼94%) and S. aureus (∼93%). In addition, the functionalized surface can release the killed bacteria (∼90%) several times efficiently under the action of lipase enzymatic degradation, restoring the original bactericidal function of the surface, thus forming a dynamic self-polishing and self-renewing antibacterial surface. Therefore, this method for the fabrication of self-polishing antibacterial surfaces may offer innovative insights into applications of biomedical implant materials. [ABSTRACT FROM AUTHOR]

Nanostructured surfaces can be engineered to kill bacteria in a contact-dependent manner. The study of bacterial interactions with a nanoscale topology is thus crucial to developing antibacterial surfaces. Here, a systematic study of the effects of nanoscale topology on bactericidal activity is presented. We describe the antibacterial properties of highly ordered and uniformly arrayed cotton swab-shaped (or mushroom-shaped) nanopillars. These nanostructured surfaces show bactericidal activity against Staphylococcus aureus and Pseudomonas aeruginosa. A biophysical model of the cell envelope in contact with the surface, developed ab initio from the infinitesimal strain theory, suggests that bacterial adhesion and subsequent lysis are highly influenced by the bending rigidity of the cell envelope and the surface topography formed by the nanopillars. We used the biophysical model to analyse the influence of the nanopillar cap geometry on the bactericidal activity and made several geometrical alterations of the nanostructured surface. Measurement of the bactericidal activities of these surfaces confirms model predictions, highlights the non-trivial role of cell envelope bending rigidity, and sheds light on the effects of nanopillar cap architecture on the interactions with the bacterial envelope. More importantly, our results show that the surface nanotopology can be rationally designed to enhance the bactericidal efficiency.

The effective and widely tested biocides: Benzalkonium chloride, bronopol, chitosan, chlorhexidine and irgasan were added in different concentrations to atelocollagen matrices. In order to assess how these antibacterial agents influence keratinocytes cell growth, cell viability and proliferation were determined by using MTT assay. Acquired data indicated a low toxicity by employing any of these chemical substances. Furthermore, cell viability and proliferation were comparatively similar to the samples where there were no biocides. It means that regardless of the agent, collagen-cell-attachment properties are not drastically affected by the incorporation of those biocides into the substrate. Therefore, these findings suggest that these atelocollagen substrates enhanced by the addition of one or more of these agents may render effectiveness against bacterial stains and biofilm formation, being the samples referred to herein as “antimicrobial substrates” a promising view in the design of novel antimicrobial biomaterials potentially suitable for tissue engineering applications.

The aim of this work was to use electrospray to create photocatalytic TiO 2 coatings and to study their antibacterial and antibiofilm capacity. The electrospray used a sol of TiO 2 anatase nanoparticles prepared by a sol–gel method, which formed stable suspensions of positively charged particles (ζ-potential + 22.3 ± 3.7 mV). The electrospray deposited TiO 2 on non-porous glass surfaces at two loading densities originating homogeneous coatings (3.2–4.3 µm) of particles the top layer of which displayed aggregates ranging from the micron scale to a few hundreds of nanometers, with lower size as TiO 2 loading increased. TiO 2 -functionalized surfaces were tested for the inactivation of the Gram-positive bacterium Staphylococcus aureus . The electrosprayed surface was moderately hydrophilic turning highly hydrophilic upon irradiation (water contact angle 9.6° after 15 h under Xe-arc lamp). photocatalytic surfaces were put in contact with exponentially growing bacterial cultures in a flow system in which solar simulated irradiation followed two different 24 h dark-light arrangements with 9 or 18 h dark exposure followed by 15 or 6 h irradiation. The electrosprayed surfaces experienced extensive colonization by viable bacteria and clear biofilm formation revealed by exopolysaccharide matrix visualization. Using both dark-light cycles all cells became non-viable with extensive membrane damage. Biofilm matrix measurements showed that the irradiated surfaces were essentially free of bacterial exopolysaccharide matrix for specimens with the higher TiO 2 loading density. The biofilm removal reached 99% and no regrowth of viable cells was observed in any case. The results showed that TiO 2 -electrospray can avoid biofilm accumulation under stringent environmental conditions. [ABSTRACT FROM AUTHOR]

Biomaterial-associated infections critically compromise the functionality and performance of the medical devices, and pose a serious threat to human healthcare. Recently, natural DNase enzyme has been recognized as a potent material to prevent bacterial adhesion and biofilm formation. However, the vulnerability of DNase dramatically limits its long-term performance in antibacterial applications. In this work, DNase-mimicking polymer brushes were constructed to mimic the DNA-cleavage activity as well as the macromolecular scaffold of the natural DNase. The bacteria repellent efficacy of DNase-mimicking polymer brush-functionalized surface was comparable to that of the DNase-functionalized surface. More importantly, due to their inherent stability, DNase-mimicking polymer brushes presented the much better performance in inhibiting bacterial biofilm development for prolonged periods of time, as compared to the natural DNase. The as-developed DNase-mimicking polymer brush-functionalized surface presents a promising approach to combat biomaterial-associated infections. [ABSTRACT FROM AUTHOR]

A photo-responsive antibacterial surface was prepared grafting non-toxic Prussian blue nanoparticles on a functionalized glass surface. Colloidal Prussian blue was synthesized as nanoparticles with cubic shape and grafted on a polyamine-functionalized SiO2surface, obtaining a good coverage and a homogeneous distribution of the nanocubes. Irradiation of these samples in the so-called ‘bio-transparent window’ of the near-infrared allows to exert a triggered antibacterial effect. [ABSTRACT FROM AUTHOR]

Antibacterial polyolefins surfaces, combining biocidal and antiadhesive properties, were elaborated by a covalent grafting of antimicrobial peptides (AMPs), able to kill adherent bacteria, on a pre-immobilized hyaluronic acid (HA) layer, able to repel the micro-organisms. Different HA activation rate for its immobilization, were used to change HA layer morphology and number of residual free carboxylic acid functions for AMPs grafting. Based on adhesion tests on Staphylococcus epidermidis and microscopy fluorescent observations, the presence of the two combined properties was shown to be depended on the HA activation rate. Thus, the best addition effect was observed for an AMP grafting on a surface based on a high HA activation, data pointing out a decrease of the bacterial adhesion up to 99.8% and a perturbation of the bacterial membrane integrity of adhered bacteria. On the contrary, a decrease of the antibacterial activity was observed for an AMP grafting on a surface based on a low HA activation. [ABSTRACT FROM AUTHOR]

In this work, laser micropolishing (LμP) was employed to reduce the surface roughness and waviness of cold-rolled AISI 304 stainless steel sheets. A pulsed fibre laser operating in the ns regime was used and the influence of laser parameters in a N 2 -controlled atmospheres was evaluated. In the optimal conditions, the surface remelting induced by the process allowed to reduce the surface roughness by closing cracks and defects formed during the rolling process. Other conditions that did not improve the surface quality were analysed for defect typology. Moreover, laser treatments allowed the production of more hydrophobic surfaces, and no surface chemistry modification was identified. Surface cleanability was investigated with Escherichia coli ( E. coli ), evaluating the number of residual bacteria adhering to the substrate after a washing procedure. These results showed that LμP is a suitable way to lower the average surface roughness by about 58% and average surface waviness by approximately 38%. The LμP process proved to be effective on the bacteria cleanability as approximately five times fewer bacteria remained on the surfaces treated with the optimized LμP parameters compared to the untreated surfaces. [ABSTRACT FROM AUTHOR]

Antibacterial surfaces such as copper coatings are able to reduce the growth of bacteria. In this study, copper coatings was deposited on the 316 stainless steel substrates by a handmade device operating as an atmospheric plasma spraying system. The chemical composition microstructure and morphology surface of the coatings are examined by x-ray diffraction (XRD) and scanning electron microscope (SEM) and back scattering electron microscope (BSE). Micro hardness as one of the key properties of the coating is characterized based on cross-section. We also evaluate the thickness and the adhesion strength of the coating. Dissection material of coating is performed by energy dispersive x-ray spectroscopy (EDX). Further, the antibacterial activity of our coatings is assessed by both gram negative Escherichia coli ATCC 10536 and gram positive Staphylococcus aureus PTCC 1112 bacteria. As the last step, the antibacterial performance of the coated stainless steel surface with copper are compared to uncoated one. Results confirm that the copper coatings improve the antibacterial property of substrates and owning fine antibacterial behavior compared to stainless steel. [ABSTRACT FROM AUTHOR]

Five different Ag dots arrays (16 to 400 dots/mm 2 ) were fabricated on a continuous platinum, palladium, or iridium thin film and for comparison also on titanium film by sputter deposition and photolithographic patterning. To analyze the antibacterial activity of these microstructured films Staphylococcus aureus ( S. aureus ) were placed onto the array surfaces and cultivated overnight. To analyze the viability of planktonic as well as surface adherent bacteria, the applied bacterial fluid was subsequently aspirated, plated on blood agar plates and adherent bacteria were detected by fluorescence microscopy. A particular antibacterial effect towards S. aureus was induced by Ag dot arrays on each of the platinum group thin film (sacrificial anode system for Ag) in contrast to Ag dot arrays fabricated on the Ti thin films (non-sacrificial anode system for Ag). Among platinum group elements the Ir-Ag system exerted the highest antibacterial activity which was accompanied by most advanced dissolution of the Ag dots and Ag ion release compared to Ag dots on Pt or Pd. [ABSTRACT FROM AUTHOR]

The relationship between microbe populations that are active on engineered-product surfaces and their relationship to surface corrosion or human health is increasingly being recognized by the materials engineering community as a critically important study-direction. Microbial contamination from biofilms and germ colonies leads to costs that are reported to be extremely high every year in infection control, epidemics, corrosion loss and energy/infrastructure materials loss throughout the world. Nanostructured surfaces, particularly those that are hard-surface nanoporous (pore radii between 2 and 1000 nm), are an emerging class of surfaces that have recently been recognized as important for the prevention of microbial colony growth and biofilm formation. Such nanostructured/nanoporous surfaces, whether made with deposited nanoparticles (welded nanoparticles), or formed by ion-assisted growth on a surface have been found to display biocidal activity with varying efficacy that depends on both the microbe and the nanosurface features. The rate of mortality from common pathogens that are resident in ubiquitous bio-films when attached to common engineering surfaces made of steels, titanium and zirconium appears to be increasing. In this short review, we look at methods of manufacture of durable (i.e., highly scratch resistant) nanostructuring on commonly used engineering surfaces. The microstructures, energy dispersive X-ray analysis, X-ray photo-electron spectroscopy and other types of characterization of a few such surfaces are presented. Simple tests are required by the surface engineering community for understanding the efficacy of a surface for antimicrobial action. These are reviewed. The surface drying rate and the dynamics of the droplet spread have been proposed in the literature as quick methods that correlate well with the residual antimicrobial activity efficacy even after some surface abrasion of the nanostructured surface. A categorization of a surface against short-term antimicrobial action and long-term action is proposed in this review article. Test periods that span time-frames greater than 5 years have demonstrated a high efficacy of the nanoporous nanostructures for preventing bio-film formation. New comparative results for diamond- and graphite-containing surfaces are presented. A brief discussion on a recently developed plasma application technique for creating durable nanoporous surfaces is presented. Although considerable information is now available regarding tunable surface nanofeatures for antimicroabial efficacy, there is a need for more research activity, particularly directed toward the low cost manufacture and rapid characterization of durable (wear and chemical resistant) surfaces that display permanent antimicrobial behavior. [ABSTRACT FROM AUTHOR]