Microstructures of biofilm

Biofilms are viewed as one of the most common form in which microorganismsexist naturally in nature. In particular, bacterial biofilms play importantroles in industrial-based problems, disease and infection and have been studied ingreat detail. However, the intrinsic structure of a biofilm is not solidly understoodwhere postulations on mechanisms, structure, chemical and biological nature andthe community are still seldom reliably described. This chapter aims to highlightsome of the most important structures contained in a biofilm—in particular microstructures.It is the microstructure of a biofilm which governs its make-up, integrityand functionality, all of which will be discussed to some level of detail

Detachment of bacteria

The rheological properties of biofilms have a great impact on major processes such as transport of nutrients, light, biocides, water, biochemicals and cells. The knowledge of the mechanical properties of biofilms is essential in quantifying the overall process of biofilm development and bacterial survival (and proliferation)—one of the key processes in a biofilm lifecycle is detachment. It is therefore crucial to be able to predict the biofilm detachment and break up in response to internal and external forces that drive the biofilm cycle. This chapter aims to highlight some of the important processes in the biofilm detachment cycle. It will also draw on some new and old concepts on this age old battle of biofilm survival and proliferation

Emerging biomaterials and strategies for medical applications : a review

The creation of new materials is one of the fundamental driving forces between research andindustry and lays the foundation for new products to enhance health and well being for the future.Antibacterial materials are an active area of research but also an economic sector in fullexpansion that addresses many application domains. It is also a world priority in terms ofreducing infection in humans for improved life and well being. Healthcare is one the largest andmost rapidly expanding needs of modern society, and smart approaches and materials arerequired to extend the boundaries required to improve the field. In this paper, we systematicallyreview a series of biomaterials and strategies that have emerged over the last decade. Inparticular, focus has been driven around the nanorealm. Some of the diverse arenas surroundingthe nanodomain and applications include drug screening technologies, biocompatibility,emerging approaches and biomimetics. In a wider front, intelligent materials are where the nextphases of research are driven, some of which are discussed herein

Biointerfaces and biofouling

Biofouling can be defined as the attachment, adhesion and proliferation of organisms on materials that causes a netnegative effect. Typically, the biofilm proliferation process is divided into two classes – micro- and macro-fouling. For thelatter, barnacles, oysters and some other relatively ‘large’ organisms play important roles in marine environments, waterpipes, heat exchangers, etc., causing series problems to the user faced with addressing the issue.Microfouling refers to theinitial layer of adhered cells whose adhesion is not reversible, which will in time develop into macrofouling. A criticalelement of these processes is the formation of a biofilm on the material’s surface. Bacteria sheathed in a biofilm have ahigher resistance to antibiotics and cleaning agents, thus increasing their overall survival probability – representing anevolutionary survival strategy. The mechanisms of bacterial adhesion are slightly different from those of macrofoulingcolonising organisms. The knowledge gained from these two basic principles has evolved since the 1990s; however, thereis still an obvious void in fundamental knowledge. The aim of this special issue is to review some recent advances inmaterials design and surface functionalisation that have been developed, on the basis of these foundation principles, tomitigate biofouling

Immunosenescence in humans : changes to the aged T Lymphocyte population in response to persistent Cytomegalovirus infection

Immunosenescence describes the decrease in immune function with advancing age, a phenomenon that is associated with changes in the B and T lymphocyte populations. CD8+ T cells display the most dramatic phenotypical and functional changes within the T cell compartment whereby the cohorts of effector and memory T cells expand while the total population and diversity of naive T cells both decline. The cause of immunosenescence is unknown; however, the accumulation of antigen-specific T cells, in particular cytomegalovirus (CMV)-specific T cells, may be a contributing factor. CMV is a beta human herpes virus that infects an extensive section of the global human population in which it may produce a lifelong, latent infection. This stimulates a highly immunogenic response that comprises a significant proportion of T cells that display a high specificity to CMV. It is postulated that this massive T cell inflation and subsequent exhaustion renders the T cell population senescent, reducing the immune system’s ability to combat pathogens as humans age. This review considers fundamental alterations in the immune system in the elderly, focusing on those changes within the CD8+ T cell population, and assesses the contribution of chronic CMV infection to immunosenescence. We propose that memory T cell inflation of CMV-infected individuals and ageing influence the functional and proliferative properties of human CMV-specific T cells, making them less efficient at controlling CMV reactivation

Sebacic and succinic acid derived plasticized PVC for the inhibition of biofouling in its initial stages

AIM: In this work, we report the use of plasticized polyvinyl chloride (PVC) as a potential antifouling coating material. The materials contain a variety of sebacic and succinic acid-derived plasticisers providing a variation in molecular shape and structure; diethyl succinate (DESn), di-(2-ethylhexyl sebacate) (DEHS), dibutyl sebacate (DBS), and diethyl sebacate (DES). Each plasticiser from the sebacate group possessed the same basic C10H16O4 moiety with varied dialkyl terminated groups, affording a different range of homologous series plasticisers. This work investigates whether branching of the side substituted alkyl chains on each plasticiser molecule affects microorganism attachment and subsequent fouling. MATERIALS AND METHODS: The plasticized polymers are spin coated to create thin films for testing. In order to determine the antifouling capacity of the materials, the polymer coatings underwent a series of analyses for biomass determination, glycocalyx production, and protein and carbohydrate adsorption. Topological and morphological characterization was performed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). RESULTS: After a 7 day laboratory biofouling study it was found that the plasticisers with increased alkyl branching, DESN, and DEHS revealed the greatest degree of prevention of microorganism colonization and attachment thus significantly reducing the initial formation of biofilms by up to 65% in some biofouling assays when compared to the uPVC blank

Nanofunctionalized superhydrophobic antifouling coatings for environmental sensor applications - advancing deployment with answers from nature

In this work, a novel preparation for superhydrophobic nanofunctionalized silver and gold, coppercoated substrates as potential antifouling coatings for environmental monitoring devices are fabricated. The superhydrophobic coating is topographically similar to the design of the Lotus leaf (Nelumbo necifera) and was synthesized by creating an electroless galvanic reaction between copper and the metal salt. In doing so, a nano- and micro-topographical structure was created on the surface of a copper substrate which can be rendered superhydrophobic through the addition of a self-assembled monolayer (SAM) of CF3(CF2)7CH2CH2SH. The work investigates whether the hydrophobicity of such materials affects micro-organism attachment and subsequent biofouling. The materials are deployed in a marine environment in Dublin, Ireland for a 6 week study to determine the overall antifouling capacity. The materials are analyzed for biomass, slime (glycocalyx) production and more specifically protein and carbohydrate adsorption all of which are attributed to the inherent makeup of biofilm and exopolymeric substances (EPS) which are secreted by micro-organisms during the biofouling process. This work highlights the dominance of combinational antifouling approaches rather than single tactics for such a complex problem and one that plagues multiple research areas. This novel approach in developing a new antifouling material for sensors, and indeed, any aquatic platform has shown excellent results throughout

The role of biomaterials in the treatment of meniscal tears

© 2017 Kean et al. Extensive investigations over the recent decades have established the anatomical, biomechanical and functional importance of the meniscus in the knee joint. As a functioning part of the joint, it serves to prevent the deterioration of articular cartilage and subsequent osteoarthritis. To this end, meniscus repair and regeneration is of particular interest from the biomaterial, bioengineering and orthopaedic research community. Even though meniscal research is previously of a considerable volume, the research community with evolving material science, biology and medical advances are all pushing toward emerging novel solutions and approaches to the successful treatment of meniscal difficulties. This review presents a tactical evaluation of the latest biomaterials, experiments to simulate meniscal tears and the state-of-the-art materials and strategies currently used to treat tears

Nanoparticles in anti-microbial materials: use and characterisation

Many nanomaterials exhibit anti-microbial properties and demand for such materials grows as new applications are found in such areas as medicine, environmental science and specialised coatings. This book documents the most up to date research on the area of nanoparticles showing anti-microbial activity and discusses their preparation and characterisation. Further materials showing potential anti-microbial properties are also discussed. With its user-friendly approach to applications, this book is an excellent reference for practical use in the lab. Its emphasis on material characterisation will benefit both the analytical and materials scientist. Frequent references to the primary literature ensure that the book is a good source of information to newcomers and experienced practitioners alike. Chapters devoted to nanoparticles, microbial impacts on surfaces and molecular biology will be essential reading, while chapters on characterisation ensure this book stands out in the field

Period four metal nanoparticles on the inhibition of biofouling

Biofilms present operational problems to a variety of industrial areas including but not limited to, medicine, water treatment, sensor sensitivity and shipping. Bacterial adhesion resides as a tiny monolayer and builds-up over time with the production of protective slimes known as extracellular polymeric substances (EPS) forming the 'biofilm'. Infection, inefficiency and diminution of quality are caused by biofilms, which have the potential to be prohibitively expensive to repair. The value of an effective coating that prevents the adhesion of bacteria and subsequent fouling is paramount in preserving sensitivity and longevity of a subjected operational substrate. Polymer and sol-gel (SG) based coatings tender a matrix for the introduction of biocides and antimicrobial agents that offer this prevention. They present a relatively cheap and optically clear platform that can then be doped with the antimicrobial agent. This proves useful in transferring across a range of industries that may require a transparent function to the coating. Nanoparticles offer a means of new line research in combating biofouling and biocorrosion with interest stemming from silver metal nanoparticles (MNPs) that already offer antimicrobial property. The aim of this work is to investigate period four metal nanoparticles for any antimicrobial potential they offer, in the prevention of fouling in the early stages. The research presented herein uses a range of period four MNPs synthesised through an adapted polyol reduction, which have then been doped into SG coatings and tested for their efficacy in preventing levels of biofouling. After a 7-day freshwater study results showed that MNPs prevent levels of biofouling upto 125% compared to the SG blank. The work uses bacterial enumeration, minimum inhibitory concentration (MIC), surface characterisation and slime and biomass analysis to complete a range of studies in assessing the level of fouling observed on the test substrates