Long-term antibacterial properties of a nanostructured titanium alloy surface: An in vitro study

The demand for joint replacement and other orthopedic surgeries involving titanium implants is continuously increasing; however, 1%–2% of surgeries result in costly and devastating implant associated infections (IAIs). Pseudomonas aeruginosa and Staphylococcus aureus are two common pathogens known to colonise implants, leading to serious complications. Bioinspired surfaces with spike-like nanotopography have previously been shown to kill bacteria upon contact; however, the longer-term potential of such surfaces to prevent or delay biofilm formation is unclear. Hence, we monitored biofilm formation on control and nanostructured titanium disc surfaces over 21 days following inoculation with Pseudomonas aeruginosa and Staphylococcus aureus. We found a consistent 2-log or higher reduction in live bacteria throughout the time course for both bacteria. The biovolume on nanostructured discs was also significantly lower than control discs at all time points for both bacteria. Analysis of the biovolume revealed that for the nanostructured surface, bacteria was killed not just on the surface, but at locations above the surface. Interestingly, pockets of bacterial regrowth on top of the biomass occurred in both bacterial species, however this was more pronounced for S. aureus cultures after 21 days. We found that the nanostructured surface showed antibacterial properties throughout this longitudinal study. To our knowledge this is the first in vitro study to show reduction in the viability of bacterial colonisation on a nanostructured surface over a clinically relevant time frame, providing potential to reduce the likelihood of implant associated infections

Bio-Inspired Nanostructured Ti-6Al-4V Alloy: The Role of Two Alkaline Etchants and the Hydrothermal Processing Duration on Antibacterial Activity

Inspired by observations that the natural topography observed on cicada and dragonfly wings may be lethal to bacteria, researchers have sought to reproduce these nanostructures on biomaterials with the goal of reducing implant-associated infections. Titanium and its alloys are widely employed biomaterials with excellent properties but are susceptible to bacterial colonisation. Hydrothermal etching is a simple, cost-effective procedure which fabricates nanoscale protrusions of various dimensions upon titanium, depending on the etching parameters used. We investigated the role of etching time and the choice of cation (sodium and potassium) in the alkaline heat treatment on the topographical, physical, and bactericidal properties of the resulting modified titanium surfaces. Optimal etching times were 4 h for sodium hydroxide (NaOH) and 5 h for potassium hydroxide (KOH). NaOH etching for 4 h produced dense, but somewhat ordered, surface nanofeatures with 75 nanospikes per µm2. In comparison, KOH etching for 5 h resulted sparser but nonetheless disordered surface morphology with only 8 spikes per µm2. The NaOH surface was more effective at eliminating Gram-negative pathogens, while the KOH surface was more effective against the Gram-positive strains. These findings may guide further research and development of bactericidal titanium surfaces which are optimised for the predominant pathogens associated with the intended application

The Impact of Engineered Silver Nanomaterials on the Immune System

Over the last decades there has been a tremendous volume of research efforts focused on engineering silver-based (nano)materials. The interest in silver has been mostly driven by the element capacity to kill pathogenic bacteria. In this context, the main area of application has been medical devices that are at significant risk of becoming colonized by bacteria and subsequently infected. However, silver nanomaterials have been incorporated in a number of other commercial products which may or may not benefit from antibacterial protection. The rapid expansion of such products raises important questions about a possible adverse influence on human health. This review focuses on examining currently available literature and summarizing the current state of knowledge of the impact of silver (nano)materials on the immune system. The review also looks at various surface modification strategies used to generate silver-based nanomaterials and the immunomodulatory potential of these materials. It also highlights the immune response triggered by various silver-coated implantable devices and provides guidance and perspective towards engineering silver nanomaterials for modulating immunological consequences

Synthèse, caractérisation et évaluation biologique de mouchoir en papier (de tissu) réalisant échafaudages pour cicatrisation des plaies

Tissue engineering is a promising therapeutic approach that assembles cells, biomaterials, and micro-environmental factors to promote tissue repair and functional restoration. Despite many advances, tissue engineers still face significant challenges in developing artifacts to promote dermal cell growth. Scaffolds are porous artifacts that serve as extracellular matrix but are able to create the microenvironment for the growth and differentiation of skin cells and enhanced tissue development. The emerging and promising next generation of engineered tissues is relying on producing biopolymeric scaffolds containing entities like growth factors, zeolites, mesoporous silica etc., that promote enhanced skin regeneration. The use of zeolites has been considered as a way to manipulate the host healing response at the site of injury to facilitate the tissue repair. Moreover, natural polymers accomplish a diverse set of functions in their native setting. The modern trend is to mimic extracellular matrix and the most appropriate way is to choose natural polymers which are biocompatible, biodegradable and non-toxic. The current study is the evaluation of the potential of using zeolites embedded tissue engineering scaffolds based on natural polymers for wound healing applications. We have tried to excavate the wound healing properties of different faujasites incorporated tissue engineering scaffolds using biopolymers like pectin, carboxymethyl cellulose, gelatin and hyaluronic acid by techniques like lyophilisation and solvent casting. The structural, mechanical, thermal, water uptake and in vitro degradation studies of the prepared composite scaffolds were investigated. The antibacterial activity, cytotoxicity and wound healing studies on Sprague Dawley rats were discussed in detail which state that zeolites incorporated scaffolds are suitable candidates for wound dressing.L'ingénierie des tissus est une approche thérapeutique prometteuse qui rassemble des cellules, des biomatériaux et des facteurs de l'environnement pour promouvoir la réparation de tissus et la restauration fonctionnelle. Malgré beaucoup de progrès, les chercheurs font toujours face à la difficulté de conception de matériaux pour promouvoir la croissance de cellules cutanées. Les squelettes (scaffolds) sont des objets poreux fabriqués qui servent de matrice extracellulaire pour créer un microenvironnement pour la croissance et la différentiation de cellules de peau et le développement de tissus améliorés. L'utilisation de zéolites a été envisagée pour faciliter la réparation des tissus. De plus, les polymères naturels accomplissent un ensemble divers des fonctions dans leur environnement biologique. Des polymères naturels, biocompatibles, biodégradables et non-toxiques ont été choisis. Cette étude consiste à évaluer le potentiel de tissus hybrides polymères-zéolites pour la guérison de blessures. Nous avons testé les propriétés de différent taux de faujasites incorporés dans l échafaudage polymère comme la pectine, carboxymethyl cellulose, la gélatine et l'acide hyaluronic par les techniques de lyophilisation et la voie solvant. Les études de structure, de propriétés mécaniques, thermiques et de dégradation ont été réalisées. L'activité antibactérienne, la cytotoxicité et la guérison de blessures effectuées sur des rats ont été discuté en détails.LORIENT-BU (561212106) / SudocSudocFranceF

Antibacterial and anti-inflammatory pH-responsive tannic acid-carboxylated agarose composite hydrogels for wound healing

pH-sensitive hydrogels play an important role in controlled drug release applications and have the potential to impact the management of wounds. In this study, we report the fabrication of novel carboxylated agarose/tannic acid hydrogel scaffolds cross-linked with zinc ions for the pH-controlled release of tannic acid. The resulting hydrogels exhibited negligible release of tannic acid at neutral and alkaline pH and sustained release at acidic pH, where they also displayed maximum swelling. The hydrogels also displayed favorable antibacterial and anti-inflammatory properties, and a lack of cytotoxicity toward 3T3 fibroblast cell lines. In simulated wound assays, significantly greater cell migration and proliferation was observed for cells exposed to tannic acid hydrogel extracts. In addition, the tannic acid hydrogels were able to suppress NO production in stimulated human macrophages in a concentration-dependent manner, indicating effective anti-inflammatory activity. Taken together, the cytocompatibility, antibacterial, and anti-inflammatory characteristics of these novel pH-sensitive hydrogels make them promising candidates for wound dressings. © 2016 American Chemical Society

Not Available

Chapter 10 of training manual "Utilization of marine bioactive compounds - Research advances and future trends"Not AvailableNot Availabl

Oxygen-releasing coatings for improved tissue preservation

Current organ transplantation protocols require the rapid transport of freshly isolated donor tissue to the recipient patient at the site where the procedure is to be conducted. During transport, the tissue graft can quickly deteriorate as a result of oxygen starvation. In this study, we report the fabrication of oxygen-releasing coatings for improved tissue preservation. The coatings were prepared via the encapsulation of calcium peroxide or urea peroxide microparticles between layers of octadiene plasma polymer films. By varying the thickness of the plasma polymer coating and type of peroxide, formulations were obtained that generate oxygen upon contact with aqueous solutions, while at the same time limiting the amount of toxic reactive oxygen species produced. The optimized coatings were tested under hypoxic conditions using the MIN6 β-cell line, which resulted in a 3-fold increase in the viability of cultured cells. These thin oxygen-releasing coatings can be deposited on a wide range of surfaces, creating a platform for oxygen delivery with the potential to extend the viability of transported tissues and increase the time frame available for graft transport

Not Available

Not AvailableThe effect of microwave blanching on quality characteristics of vacuum and conventional polyethylenepacked sutchi catfish fillets was evaluated under chilled condition. Emphasis has been given to retain the sensory characteristics such as colour and textural properties, which is a major problem in sutchi catfish fillets during extended chill storage. In general, microwave blanching imposed minimum changes on fatty acid and mineral composition of fish meat. A marginal increase in fat content was recorded after microwave heating of fish fillets. The microwave-blanched fillets showed minimum cooking loss of 3.2 mL per 100 g meat. A slower increase in spoilage parameters was obtained with microwave-blanched samples compared with unblanched samples, demonstrating the higher storage stability of the sample under chilled conditions. Microwave heating of fish fillets coupled with quick-chilling and packing under vacuum improved the colour and texture stability of sutchi catfish fillets to a considerable extent. Microwave blanching increased the hardness and chewiness values and decreased the stiffness values of fish fillets. The biochemical and sensory evaluation of microwave-blanched and vacuum-packed sutchi catfish fillets showed extended storage life of 21 days, compared with 12 days for unblanched vacuum-packed samplesNot Availabl