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

Monitoring of priority substances in waste water effluents : monitoring criteria for priority chemicals leading to emission factors

The pollution of water by chemicals and other pollutants affects all life on Earth as habitats and ecosystems are disturbed, and biodiversity is reduced. The Water Quality (Dangerous Substances) Regulations, SI 12 of 2001, prescribe water quality standards in relation to certain substances in surface waters, for example rivers, lakes and tidal waters. The Regulations give further effect to the European Union (EU) Dangerous Substances Directive (76/464/EC) and give effect to certain provisions of the EU Water Framework Directive (WFD) (2000/60/EC). In 2003 and 2004, Ireland’s National Dangerous Substances Expert Group developed lists of priority action, candidate relevant pollutant and candidate general component substances for surface waters in Irelandand designed a substances screening monitoring programme as part of the implementation of the WFD. Many knowledge gaps exist in relation to managing PSs and PHSs in Irish waters. The objective of the EPA-funded project (Monitoring Criteria for Priority Chemicals Leading to Emission Factors) was to develop a model based on emission criteria in order to assist the monitoring of PSs. This project, which started in 2008, represents an important collaboration between two research centres (Dublin City University and Cork Institute of Technology) with analytical expertise, and three councils (Fingal, Cork and Dublin Councils), building capability to establish risk factors for PSs and PHSs

Characterisation of nano-antimicrobial materials

The potential applications of nano-antimicrobial materials are well recognised. A large suite of characterisation techniques are available for the study of nano-antimicrobial materials. The choice of technique depends on the material properties in question and the information required. The focus of this chapter is on the surface and interface techniques as these provide information on material activity and efficacy. Antimicrobial properties of a nanomaterial must be characterised in terms of two interrelated aspects. The nature of the chemical and physical properties of the nanomaterial in question must be fully characterised in terms of, i.e. particle morphology and the elemental composition of the particle. Subsequently, it is necessary to characterise the material in terms of antimicrobial potential. This chapter provides a general guide and overview of characterisation techniques available to researchers studying nano-antimicrobial materials, including key microscopic methods, spectroscopic methods, and some physical surface characterisation methods. The chapter identifies how these techniques can be used to study the physical characteristics of the nanomaterials themselves and the antimicrobial effects on the material surface

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

Combating bio-fouling of sensors and environmental platforms in the marine environment

Bio-fouling is a ubiquitous natural process whereby organisms such as bacteria, algae or invertebrates form a living biological layer, typically at the interface between a solid surface and an aqueous environment. The build up of biofouling is a process that can impair the function of many artificial mechanical devices across a number of different disciplines, ranging from medicine to engineering and marine transport. This work shows the development of novel materials based on bio-inspired design and novel polymeric coatings for prevention of anti-fouling on sensor housings. Results of tested anti-fouling coatings are presented. The effect of topographic features is shown to impact on the settlement of diatoms in the early stages of biofilm formation. Novel polymeric coatings show promise in prevention of bacterial attachment. The results from the deployment of antifouling materials together with real-time water quality data from the test site is shown

Continuous high-frequency monitoring of estuarine water quality as a decision support tool : a Dublin Port case study

High-frequency, continuous monitoring using in situ sensors offers a comprehensive and improved insight into the temporal and spatial variability of any water body. In this paper, we describe a 7-month exploratory monitoring programme in Dublin Port, demonstrating the value of high frequency data in enhancing knowledge of processes, informing discrete sampling, and ultimately increasing the efficiency of port and environmental management. Kruskal–Wallis and Mann–Whitney tests were used to show that shipping operating in Dublin Port has a small–medium effect on turbidity readings collected by in situ sensors. Turbidity events are largely related to vessel activity in Dublin Port, caused by re-suspension of sediments by vessel propulsion systems. The magnitudes of such events are strongly related to water level and tidal state at vessel arrival times. Crucially, measurements of Escherichia coli and enterococci contamination from discrete samples taken at key periods related to detected turbidity events were up to nine times higher after vessel arrival than prior to disturbance. Daily in situ turbidity patterns revealed time-dependent water quality “hot spots” during a 24-h period. We demonstrate conclusively that if representative environmental assessment of water quality is to be performed at such sites, sampling times, informed by continous monitoring data, should take into account these daily variations. This work outlines the potential of sensor technologies and continuous monitoring, to act as a decision support tool in both environmental and port management

Reproducible superhydrophobic PVC coatings: Investigating the use of plasticizers for early stage biofouling control

Here we show an easy to synthesize superhydrophobic material using a solvent phase–separation process of poly vinyl chloride. It is found that solvents mixed in different ratios increase the dielectric value of the solvent and can be tuned to produce superhydrophobic PVC. The PVC solution is then spin-coated onto glass slides for characterization using scanning electron microscopy. Plasticizers are doped into the 70% (v/v) PVC to determine their overall effects; it is found that plasticizers reduce the water contact angle value. The final coatings were tested in a series of antifouling assays in a marine environment lab study; it is found that the superhydrophobic PVC material reduced marine biofouling

Phthalate doped PVC membranes for the inhibition of fouling

Four phthalate plasticizers, each with different structural characteristics were assessed within a poly (vinylchloride) (PVC) matrix for their potential as an antifouling material. The materials contained phthalic ester compounds: dimethyl phthalate (DMP), diethyl phthalate (DEP), butyloctyl phthalate (BOP) and di-(2-ethylhexyl) phthalate (DEHP) and were prepared at 5% w/v concentration. The phthalates all possess the same phthalic ester C6H4COCO moiety with structural differences of chain length and branching across the four plasticizer compounds. This poses a question as to whether alkyl chain length does affect microorganism attachment and subsequent fouling. In order to determine the antifouling capacity of the materials, the polymer coatings underwent a series of analyses for biomass determination, biological assessment, glycocalyx production, contact angle determination, surface roughness using atomic force microscopy (AFM) and topological characterisation through scanning electron microscopy (SEM). It was found that using a 7-day fresh water tank study, the increased branched and longer chain phthalic esters, in DEHP and BOP gave rise to better antifouling performance. A pure culture study involving the test membranes in Staphylococcus aureus and Escherichia coli cell suspensions, displayed less cellular attachment on the DEHP and BOP doped PVC matrices, once again showing potential in preventing cellular attachment and biofouling