Enhancement of the Antibacterial Properties of Silver Nanoparticles Using Beta-Cyclodextrin as a Capping Agent

Silver nanoparticles (AgNPs) were synthesized by reducing silver salts using NaBH4 followed by capping with varying concentrations of β-cyclodextrin (β-CD) and were physically characterised. Antibacterial activity against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus was determined by a microtitre well method. The AgNPs were spherical under TEM while DLS showed average diameters of capped particles to be smaller (4-7 nm) than their uncapped equivalents (17 nm). Capped particles demonstrated superior photostability when exposed to intense UV radiation for 4 hours and a significantly (

Silver Doped Perfluoropolyether-Urethane Coatings: Antibacterial Activity and Surface Analysis

The colonisation of clinical and industrial surfaces with pathogenic microorganisms has prompted increased research into the development of effective antibacterial and antifouling coatings. There is evidence that implanted biomedical surfaces coated with metallic silver can be inactivated by hysiological fluids, thus reducing the bioactivity of the coating. In this work, we report the biofilm inhibition of Staphylococcus epidermidis using a roomtemperatureprocessedsilver dopedperfluoropolyether-urethane coating. The release of silver ions from these fluoropolymers over a six-day period inhibited bacterial encrustation – as observed by scanning electron microscopy (SEM). X-ray photoelectron spectroscopy (XPS) analysis indicated differences in carbon, fluorine and sodium surface composition between silver doped and undoped fluoropolymers after exposure to nutrient rich media. These silver doped perfluoropolyether coatings also exhibited antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, Pseudomonas aeruginosa and Acinetobacter baumannii; suggesting potential use in preventing transmission of pathogenic and opportunistic microbes on environmental surfaces in healthcare facilities. The broad-spectrum antibacterial activity of these silver release coatings may be exploited on biomaterials surfaces to combat the development of resistant Gram-negative Enterobacteriaceae that can occur during prophylactic treatment for urinary tract infections

Protective Properties of Functionalised Tetrazine on an Aerospace Aluminium Alloy (AA 2024-T3)

Environmental health concerns over conventional chromium based surface treatments on aluminium substrates are well known. Current research efforts have concentrated on developing protective technologies for multiple applications. Such properties would enable manufacturers to address both corrosion and bacterial threats in areas such as fuel tanks and delivery systems. The present study explores the anticorrosion properties of 1,2-dihydro 1, 2, 4, 5 tetrazine-3, 6-dicarboxylic acid (H2DCTZ) on a copper rich aerospace aluminium alloy (AA 2024-T3). Furthermore the antimicrobial activity of the tetrazine is evaluated against Gram-positive and Gram-negative bacteria, both capable of inducing corrosion. The protective action of the tetrazine was investigated at different concentrations in a chloride ion rich environment (3.5% (w/v) NaCl) utilising electrochemical impedance spectroscopy (EIS). Results over a 72 h period proved that an optimum concentration was 500 ppm. FTIR and SEM elemental mapping of the surface confirmed the nitrogen rich tetrazine affinity for the copper rich intermetallic sites, through coordinate bonds, which delayed corrosion onset and reduced pit formation. Moderate antibacterial tetrazine activity was observed against Escherichia coli and 100% efficacy against Staphylococcus aureus at 250 ppm was achieved. The damage of the bacterial cell envelope at the critical concentrations (250 ppm) is proposed as a possible mechanism for antibacterial action

Prospectus, September 21, 1994

https://spark.parkland.edu/prospectus_1994/1013/thumbnail.jp

Future cost-effectiveness and equity of the NHS Health Check cardiovascular disease prevention programme: Microsimulation modelling using data from Liverpool, UK

Background: Aiming to contribute to prevention of cardiovascular disease (CVD), the National Health Service (NHS) Health Check programme has been implemented across England since 2009. The programme involves cardiovascular risk stratification—at 5-year intervals—of all adults between the ages of 40 and 74 years, excluding any with preexisting vascular conditions (including CVD, diabetes mellitus, and hypertension, among others), and offers treatment to those at high risk. However, the cost-effectiveness and equity of population CVD screening is contested. This study aimed to determine whether the NHS Health Check programme is cost-effective and equitable in a city with high levels of deprivation and CVD. Methods and findings: IMPACTNCD is a dynamic stochastic microsimulation policy model, calibrated to Liverpool demographics, risk factor exposure, and CVD epidemiology. Using local and national data, as well as drawing on health and social care disease costs and health-state utilities, we modelled 5 scenarios from 2017 to 2040: Scenario (A): continuing current implementation of NHS Health Check; Scenario (B): implementation ‘targeted’ toward areas in the most deprived quintile with increased coverage and uptake; Scenario (C): ‘optimal’ implementation assuming optimal coverage, uptake, treatment, and lifestyle change; Scenario (D): scenario A combined with structural population-wide interventions targeting unhealthy diet and smoking; Scenario (E): scenario B combined with the structural interventions as above. We compared all scenarios with a counterfactual of no-NHS Health Check. Compared with no-NHS Health Check, the model estimated cumulative incremental cost-effectiveness ratio (ICER) (discounted £/quality-adjusted life year [QALY]) to be 11,000 (95% uncertainty interval [UI] −270,000 to 320,000) for scenario A, 1,500 (−91,000 to 100,000) for scenario B, −2,400 (−6,500 to 5,700) for scenario C, −5,100 (−7,400 to −3,200) for scenario D, and −5,000 (−7,400 to −3,100) for scenario E. Overall, scenario A is unlikely to become cost-effective or equitable, and scenario B is likely to become cost-effective by 2040 and equitable by 2039. Scenario C is likely to become cost-effective by 2030 and cost-saving by 2040. Scenarios D and E are likely to be cost-saving by 2021 and 2023, respectively, and equitable by 2025. The main limitation of the analysis is that we explicitly modelled CVD and diabetes mellitus only. Conclusions: According to our analysis of the situation in Liverpool, current NHS Health Check implementation appears neither equitable nor cost-effective. Optimal implementation is likely to be cost-saving but not equitable, while targeted implementation is likely to be both. Adding structural policies targeting cardiovascular risk factors could substantially improve equity and generate cost savings

An investigation into the effects of current immunosuppressants and novel compounds on animal models of asthma and delayed type hypersensitivity

THESIS 8536Asthma is a disease with a worldwide distribution and of increasing prevalence. There are two forms of the disease; intrinsic, which is believed to follow a Th1 cytokine profile and extrinsic, which follows a Th2 response. A problem with many current treatments is the side effects they cause at high doses. For this reason, a number of novel compounds were evaluated in animal models of delayed type hypersensitivity (DTH) and asthma. In extrinsic asthma, an allergen stimulates a Th2 response, IgE production from B cells and mast cell degranulation, causing the release of eicosanoids and various cytokines. This stimulates the recruitment of leukocytes such as eosinophils and neutrophils to the lungs and ultimately leads to hypersensitivity of the airways. Bronchial hyper-reactivity also occurs following leukocyte recruitment in intrinsic asthma although it may follow a Th1 response and has not been shown to involve mast cells or IgE production

Preparation and Rapid Analysis of Antibacterial Silver, Copper and Zinc Doped Sol–gel Surfaces

The colonisation of clinical and industrial surfaces with microorganisms, including antibiotic-resistant strains, has promoted increased research into the development of effective antibacterial and antifouling coatings. This study describes the preparation of metal nitrate (Ag, Cu, Zn) doped methyltriethoxysilane (MTEOS) coatings and the rapid assessment of their antibacterial activity using polyproylene microtitre plates. Microtitre plate wells were coated with different volumes of liquid sol–gel and cured under various conditions. Curing parameters were analysed by thermogravimetric analysis (TGA) and visual examination. The optimum curing conditions were determined to be 50–70C using a volume of 200ul. The coated wells were challenged with Gram-positive and Gram-negative bacterial cultures, including biofilm-forming and antibiotic-resistant strains. The antibacterial activities of the metal doped sol–gel, at equivalent concentrations, were found to have the following order: silver > zinc > copper. The order is due to several factors, including the increased presence of silver nanoparticles at the sol–gel coating surface, as determined by X-ray photoelectron spectroscopy, leading to higher elution rates as measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The use of microtitre plates enabled a variety of sol–gel coatings to be screened for their antibacterial activity against a wide range of bacteria in a relatively short time. The broad-spectrum antibacterial activity of the silver doped sol–gel showed its potential for use as a coating for biomaterials