Implanted medical device infections represent a significant clinical challenge. Infections, often caused by staphylococcal species, are extremely difficult to treat due to challenges in targeting the infection site whilst avoiding systemic toxicity. This study reports on the development of a novel implant coating to provide controlled, local drug-release, for the inhibition of infection. The release of the broad-spectrum antibiotic rifampicin from a range of biodegradable poly (lacticacid) (PLA) and poly (lactic-co-glycolic acid) (PLGA) polymer formulations was analysed. Increasing the fraction of polymer in a formulation provided control over release; e.g. increasing the PLGA:rifampicin ratio from 25:75 to 75:25 significantly (p ≤ 0.001) slowed release of rifampicin from >99%, to <2% after 7 days. The antimicrobial activity of PLGA:rifampicin based formulations (25:75, 50:50, 75:25) against Staphylococcus aureus revealed that all formulations retained antimicrobial activity over 7 days in disk diffusion tests. The 50:50 formulation produced significantly (p ≤ 0.05) larger zones of growth inhibition than the 25:75 or 75:25 formulations. This investigation confirms rifampicin can be released from biocompatible, polymer-based coatings, and reveals potential for engineering both the release rate and level of antimicrobial efficacyClinical Relevance— This research demonstrates the potential of synthetic polymer coatings for the prevention of medical implant infections.

Despite polyester vascular grafts being routinely used in life-saving aortic aneurysm surgeries, they are less compliant than the healthy, native human aorta. This mismatch in mechanical behaviour has been associated with disruption of haemodynamics contributing to several long-term cardiovascular complications. Moreover, current fabrication approaches mean that opportunities to personalise grafts to the individual anatomical features are limited. Various modifications to graft design have been investigated to overcome such limitations; yet optimal graft functionality remains to be achieved. This study reports on the development and characterisation of an alternative vascular graft material. An alginate:PEGDA (AL:PE) interpenetrating polymer network (IPN) hydrogel has been produced with uniaxial tensile tests revealing similar strength and stiffness (0.39 ± 0.05 MPa and 1.61 ± 0.19 MPa, respectively) to the human aorta. Moreover, AL:PE tubular conduits of similar geometrical dimensions to segments of the aorta were produced, either via conventional moulding methods or stereolithography (SLA) 3D-printing. While both fabrication methods successfully demonstrated AL:PE hydrogel production, SLA 3D-printing was more easily adaptable to the fabrication of complex structures without the need of specific moulds or further post-processing. Additionally, most 3D-printed AL:PE hydrogel tubular conduits sustained, without failure, compression up to 50% their outer diameter and returned to their original shape upon load removal, thereby exhibiting promising behaviour that could withstand pulsatile pressure in vivo. Overall, these results suggest that this AL:PE IPN hydrogel formulation in combination with 3D-printing, has great potential for accelerating progress towards personalised and mechanically-matched aortic grafts.

Diamond-like carbon thin films have emerged as durable, chemically stable optical coatings for many optical and optoelectronics applications due to their hardness, chemical inertness, and optical transparency. This paper presents a novel high-energy electron cyclotron resonance ion beam sputter deposition technique to fabricate pure diamond-like carbon coatings at room temperature. The chemical composition of the deposited coatings including ratios of sp2/sp3 bonding in the thin films were determined by X-ray photoelectron spectroscopy. Results indicate that the sp3 percentage ranges from 45% - 85%. The transmission and reflectance spectra of the coatings were measured from UV to IR ({\lambda}= 185 to 2500 nm) by utilizing a spectrophotometer. The measured spectra were analysed by the Tauc method to determine the optical band gap and Urbach energy and an optical fitting software, which utilizes the model modified by OJL, to extract the refractive index and extinction coefficient. By varying the ion energy, the optical properties were found to be n = 2.30 - 2.51, band gap energy = 0.4 - 0.68 eV, and the Urbach energy = 0.33 - 0.49 eV. This study provides a flexible method for tuning the structural, optical, and electronic properties of diamond-like carbon coatings by controlling the ion energy during deposition.

Respiratory epithelial cells fail to exhibit natural phenotypic and morphological characteristics when grown in standard cell culture conditions. To better understanding respiratory pathogen host-cell interactions in the airways, one approach is to instead grow and differentiate these cells at an air-liquid interface (ALI). This chapter provides the working protocols used in our lab for producing ALI cultures, infecting them with SARS-CoV-2 and monitoring viral replication.

Background: A novel single-use, analyser-free, molecular point-of-care test for SARS-CoV-2 (Veros COVID-19 test, Sherlock Biosciences) could reduce time to results and improve patient care and flow in the emergency department (ED), but its performance in this setting is unknown. Methods: Adults aged >= 18 years presenting to Southampton General Hospital (UK) with suspected COVID-19 were tested with the Veros COVID-19 test in addition to standard of care near-patient PCR. Measures of diagnostic accuracy were calculated for the Veros COVID-19 test stratified by Ct value. Discrepant results underwent viral culture. Findings: Between Jan 16 and May 2, 2023, 400 patients were enrolled with a median (IQR) age of 60 (34-77) and 141 (353%) were SARS-CoV-2 positive by PCR. The Veros test gave valid results on the first test in 384 (960%), and sensitivity and specificity were 127/141 (901%, 95%CI 839-945) and 258/259 (996%, 95%CI 979-100) overall. For those with high or moderate viral load (Ct <= 30), sensitivity was 125/129 (969%, 95%CI 923-992). One (71%) of 14 PCR positive/Veros test negative samples was culture positive. Median (IQR) time from sample collection to result was 19 (18-20) mins with the Veros test versus 73 (59-92) mins with PCR (p < 00001). Interpretation: The Veros COVID-19 test generated results in near real-time, around 1 h sooner than rapid, near-patient, analyser-based PCR, and accuracy was excellent for samples with moderate and high viral loads. The Veros test represents a step-change in molecular diagnostics for infection and could significantly reduce time to results and improve patient management in EDs and other settings (c) 2024 The Author(s). Published by Elsevier Ltd on behalf of The British Infection Association. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Cardiovascular disease remains the leading cause of global deaths and a major contributor to disability. This includes aortic valve stenosis (AS), affecting 9 million people worldwide and mitral regurgitation (MR), affecting 24 million people worldwide. In the UK, mortality in patients with untreated severe AS is estimated to be as high as 50% and 97% at 2- and 5- years, presenting a diagnosis crisis in an aging population. In middle- and low- income countries, rheumatic heart disease remains the most prevalent cause in young adults. Valve replacement with a prosthesis remains the most effective treatment against AS, presenting a lifesaving procedure. However, complications include calcification, durability and a need for lifelong anti-coagulant therapy. Polymer heart valves can bridge the durability of mechanical heart valves with the haemocompatibility of biological valves and at a fraction of the cost. Yet, despite advances in polymer science, there has been little change in leaflet design and very few have reached clinical translation. The Wheatley Heart Valve (WHV) is a novel patented polymer valve comprised of a series of contiguous circles designed to facilitate helical blood flow through the aorta. This minimises bending stresses and generates a sinus washout of blood, alleviating the risks from thrombosis. Moreover, it can be manufactured from a flat sheet, expanding the possibilities for adaptations such as surface treatments and leaflet reinforcements. Early computational fluid models confirm the unique curvature of the WHV facilitates helical blood flow downstream of the valve. Through a multi-disciplinary team consisting of clinicians, biomedical engineers, mathematicians, physicists and manufacturing experts, this research sets out to validate and optimise the design of this technology. By integrating the complex relationships between blood-surface properties, haemodynamics, leaflet design and advanced manufacturing techniques, this approach will advance the WHV closer to clinical translation. Acknowledgements We are grateful to Tenovus Scotland Strathclyde for supporting this project.

A novel high-energy electron cyclotron resonance (ECR) ion beam deposition (IBD) technique was used to fabricate DLC films at different ion beam energies. The ratios of sp2/sp3 bonding in the DLC coatings were determined by Raman spectroscopy and XPS, with the confirmation of being hydrogen-free due to the lack of photoluminescence (PL) background in the Raman spectra. The results indicate that the sp3 percentage ranges from 45 fabricated DLC films in this study. Monte-Carlo based SRIM simulation was used to extract the energy and angular distribution of the sputtered particles from the carbon target and correlate it to the highest sp3 fraction in the manufactured ECR-IBD DLCs. This study demonstrates a method of depositing DLC thin films under ambient conditions (room temperature with no post-annealing or additional bias voltage applied) which produces high-sp3 coatings (higher than those traditionally reported for other sputtering methods) suitable for applications where high quality DLC coatings are required.

With increasing age, the risk of cardiovascular disease such as stroke and heart attack, increases in humans due to structural and mechanical changes within the cardiovascular system. This is due to many factors that occur in advanced age, such as increased arterial stiffness and intra-plaque and medial arterial calcification. Other diseases such as diabetes and hypo- or hypertension also increase the risk of developing arterial problems. Medial calcification is driven by the aging process, as well as diseases such as diabetes and chronic kidney disease. During medial calcification smooth muscle cells (SMCs) within the medial layer of the arterial wall undergo processes similar to bone formation, due to continuous calcium phosphate diffusion. With increasing age or due to diseases the inhibitors that avoid an accumulation of those minerals within the blood vessels, become less effective and functional. This then causes phenotypical changes within vascular SMCs (VSCMs) to osteocytic and osteoblastic type cells. However, the exact morphologies are mostly still unknown. The development of an organ-on-a-chip (OOC) model could help to further the understanding of the changes that the cells undergo, as it would provide a functional and easily manipulated in vitro system of medial calcification. Furthermore, it could also provide a possibility to be used as a model for other cardiovascular research interests.

The true nature of the population spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in populations is often not fully known as most cases, particularly in Africa, are asymptomatic. Finding the true magnitude of SARS-CoV-2 spread is crucial to provide actionable data about the epidemiological progress of the disease for researchers and policymakers. This study developed and optimized an antibody enzyme-linked immunosorbent assay (ELISA) using recombinant nucleocapsid antigen expressed in-house using a simple bacterial expression system. Nucleocapsid protein from SARS-CoV-2 was expressed and purified from Escherichia coli. Plasma samples used for the assay development were obtained from Ghanaian SARS-CoV-2 seropositive individuals during the pandemic, while seronegative controls were plasma samples collected from blood donors before the coronavirus disease 2019 (COVID-19) pandemic. Another set of seronegative controls was collected during the COVID-19 pandemic. Antibody detection and levels within the samples were validated using commercial kits and Luminex. Analyses were performed using GraphPad Prism, and the sensitivity, specificity and background cut-off were calculated. This low-cost ELISA (£0.96/test) assay has a high prediction of 98.9

Severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) has had a tremendous impact on humanity. Prevention of transmission by disinfection of surfaces and aerosols through a chemical-free method is highly desirable. Ultraviolet C (UVC) light is uniquely positioned to achieve inactivation of pathogens. We report the inactivation of SARS-CoV-2 virus by UVC radiation and explore its mechanisms. A dose of 50 mJ/cm2 using a UVC laser at 266 nm achieved an inactivation efficiency of 99.89%, while infectious virions were undetectable at 75 mJ/cm2 indicating >99.99% inactivation. Infection by SARS-CoV-2 involves viral entry mediated by the spike glycoprotein (S), and viral reproduction, reliant on translation of its genome. We demonstrate that UVC radiation damages ribonucleic acid (RNA) and provide in-depth characterization of UVC-induced damage of the S protein. We find that UVC severely impacts SARS-CoV- 2 spike protein's ability to bind human angiotensin-converting enzyme 2 (hACE2) and this correlates with loss of native protein conformation and aromatic amino acid integrity. This report has important implications for the design and development of rapid and effective disinfection systems against the SARS-CoV-2 virus and other pathogens.

Many solid tumours (e.g. sarcoma, carcinoma and lymphoma) form a disorganized neo-vasculature that initiates uncontrolled vessel formation to support tumour growth. The complexity of these environments poses a significant challenge for tumour medicine research. While animal models are commonly used to address some of these challenges, they are time-consuming and raise ethical concerns. In vitro microphysiological systems have been explored as an alternative, but their production typically requires multi-step lithographic processes that limit their production. In this work, a novel approach to rapidly develop multi-material tissue-mimicking, cell-compatible platforms able to represent the complexity of a solid tumour's neo-vasculature is investigated via stereolithography three-dimensional printing. To do so, a series of acrylate resins that yield covalently photo-cross-linked hydrogels with healthy and diseased mechano-acoustic tissue-mimicking properties are designed and characterized. The potential viability of these materials to displace animal testing in preclinical research is assessed by studying the morphology, actin expression, focal adhesions and nitric oxide release of human umbilical vein endothelial cells. These materials are exploited to produce a simplified multi-material three-dimensional printed model of the neo-vasculature of a solid tumour, demonstrating the potential of our approach to replicate the complexity of solid tumours in vitro without the need for animal testing.

Since the introduction of percutaneous coronary intervention (PCI) for the treatment of obstructive coronary artery disease (CAD), patient outcomes have progressively improved. Drug eluting stents (DES) that employ anti-proliferative drugs to limit excess tissue growth following stent deployment have proved revolutionary. However, restenosis and a need for repeat revascularisation still occurs after DES use. Over the last few years, computational models have emerged that detail restenosis following the deployment of a bare metal stent (BMS), focusing primarily on contributions from mechanics and fluid dynamics. However, none of the existing models adequately account for spatiotemporal delivery of drug and the influence of this on the cellular processes that drive restenosis. In an attempt to fill this void, a novel continuum restenosis model coupled with spatiotemporal drug delivery is presented. Our results indicate that the severity and time-course of restenosis is critically dependent on the drug delivery strategy. Specifically, we uncover an intricate interplay between initial drug loading, drug release rate and restenosis, indicating that it is not sufficient to simply ramp-up the drug dose or prolong the time course of drug release to improve stent efficacy. Our model also shows that the level of stent over-expansion and stent design features, such as inter-strut spacing and strut thickness, influence restenosis development, in agreement with trends observed in experimental and clinical studies. Moreover, other critical aspects of the model which dictate restenosis, including the drug binding site density are investigated, where comparisons are made between approaches which assume this to be either constant or proportional to the number of smooth muscle cells (SMCs). Taken together, our results highlight the necessity of incorporating these aspects of drug delivery in the pursuit of optimal DES design.

Genome replication of positive strand RNA viruses requires the production of a complementary negative strand RNA that serves as a template for synthesis of more positive strand progeny. Structural RNA elements are important for genome replication, but while they are readily observed in the positive strand, evidence of their existence in the negative strand is more limited. We hypothesized that this was due to viruses differing in their capacity to allow this latter RNA to adopt structural folds. To investigate this, ribozymes were introduced into the negative strand of different viral constructs; the expectation being that if RNA folding occurred, negative strand cleavage and suppression of replication would be seen. Indeed, this was what happened with hepatitis C virus (HCV) and feline calicivirus (FCV) constructs. However, little or no impact was observed for chikungunya virus (CHIKV), human rhinovirus (HRV), hepatitis E virus (HEV), and yellow fever virus (YFV) constructs. Reduced cleavage in the negative strand proved to be due to duplex formation with the positive strand. Interestingly, ribozyme-containing RNAs also remained intact when produced in vitro by the HCV polymerase, again due to duplex formation. Overall, our results show that there are important differences in the conformational constraints imposed on the folding of the negative strand between different positive strand RNA viruses.

Drug-filled implants (DFIs) have emerged as an innovative approach to control the delivery of drugs. These devices contain the drug within the structure of the implant itself and avoid the need to include additional drug carrier materials such as a polymers, which are often associated with inflammation and delayed healing/tissue regeneration at the implant site. One common feature of in vitro experiments to generate drug release profiles is stirring or agitation of the release medium. However, the influence of the resulting fluid flow on the rate of drug release from DFIs has yet to be quantified. In this paper we consider two DFIs, which although similar in shape and size, employ different strategies to control the release of drug: a porous pin with pores on the order of μ m and a pin drilled with orifices of the order of mm. We develop a multiphysics mathematical model of drug release from these DFIs, subject to fluid flow induced through stirring and show that fluid flow greatly influences the drug release profile for the orifice pin, but that the porous pin drug release profile is relatively insensitive to flow. We demonstrate that drug release from the porous pin may adequately be described through a simplified radial 1D dissolution-diffusion model, while a 3D dissolution-advection-diffusion model is required to describe drug release from the orifice pin. A sensitivity analysis reveals that that the balance of reaction-advection-diffusion in terms of key nondimensional numbers governs the overall drug release. Our findings potentially have important implications in terms of devising the most relevant experimental protocol for quantifying drug release from DFIs.

Pyocyanin production by Pseudomonas aeruginosa can be monitored using hyperspectral imaging and square wave voltammetry, with electrochemical impedance spectroscopy offering new avenues for low-cost sensing approaches to biofilm characterisation.

In the last decade, many computational models have been developed to describe the transport of drug eluted from stents and the subsequent uptake into arterial tissue. Each of these models has its own set of limitations: for example, models typically employ simplified stent and arterial geometries, some models assume a homogeneous arterial wall, and others neglect the influence of blood flow and plasma filtration on the drug transport process. In this study, we focus on two common limitations. Specifically, we provide a comprehensive investigation of the influence of arterial curvature and plaque composition on drug transport in the arterial wall following drug-eluting stent implantation. The arterial wall is considered as a three-layered structure including the subendothelial space, the media and the adventitia, with porous membranes separating them (endothelium, internal and external elastic lamina). Blood flow is modelled by the Navier-Stokes equations, while Darcy's law is used to calculate plasma filtration through the porous layers. Our findings demonstrate that arterial curvature and plaque composition have important influences on the spatiotemporal distribution of drug, with potential implications in terms of effectiveness of the treatment. Since the majority of computational models tend to neglect these features, these models are likely to be under- or over-estimating drug uptake and redistribution in arterial tissue.

Coronary stents are now the most widely used revascularization treatment for coronary heart disease. Their performance has been greatly enhanced through various developments in the stent platform, materials, and deployment technique. Perhaps the most significant of these developments has been the introduction of drug-eluting stents (DES), with these devices achieving dramatic reductions in restenosis, previously the Achilles heel of bare-metal stents. A great variety of newer generation DES have since been developed, but there has only been a relatively modest improvement in clinical outcomes achieved with these more recent devices. Similarly, the clinical potential of bioresorbable stents has yet to be realized. This chapter charts the key developments in drug-eluting stent technology and identifies challenges to further progress. This chapter also considers how in silico models and advanced monitoring systems may provide better understanding of existing device performance, with a view to identifying opportunities for future development.

The advent of drug-eluting stents (DES) has revolutionised the treatment of coronary artery disease. These devices, coated with anti-proliferative drugs, are deployed into stenosed or occluded vessels, compressing the plaque to restore natural blood flow, whilst simultaneously combating the evolution of restenotic tissue. Since the development of the first stent, extensive research has investigated how further advancements in stent technology can improve patient outcome. Mathematical and computational modelling has featured heavily, with models focussing on structural mechanics, computational fluid dynamics, drug elution kinetics and subsequent binding within the arterial wall; often considered separately. Smooth Muscle Cell (SMC) proliferation and neointimal growth are key features of the healing process following stent deployment. However, models which depict the action of drug on these processes are lacking. In this article, we start by reviewing current models of cell growth, which predominantly emanate from cancer research, and available published data on SMC proliferation, before presenting a series of mathematical models of varying complexity to detail the action of drug on SMC growth in vitro. Our results highlight that, at least for Sodium Salicylate and Paclitaxel, the current state-of-the-art nonlinear saturable binding model is incapable of capturing the proliferative response of SMCs across a range of drug doses and exposure times. Our findings potentially have important implications on the interpretation of current computational models and their future use to optimise and control drug release from DES and drug-coated balloons.

Angiotensin-converting enzyme 2 (ACE2) is the main entry point in airway epithelial cells for SARS-CoV-2. ACE2 binding to the SARS-CoV-2 protein spike triggers viral fusion with the cell plasma membrane, resulting in viral RNA genome delivery into the host. Despite ACE2's critical role in SARS-CoV-2 infection, full understanding of ACE2 expression, including in response to viral infection, remains unclear. ACE2 was thought to encode five transcripts and one protein of 805 amino acids. In the present study, we identify a novel short isoform of ACE2 expressed in the airway epithelium, the main site of SARS-CoV-2 infection. Short ACE2 is substantially upregulated in response to interferon stimulation and rhinovirus infection, but not SARS-CoV-2 infection. This short isoform lacks SARS-CoV-2 spike high-affinity binding sites and, altogether, our data are consistent with a model where short ACE2 is unlikely to directly contribute to host susceptibility to SARS-CoV-2 infection.

Background Controlling the spread of SARS-CoV-2 is problematic because of transmission driven by asymptomatic and pre-symptomatic individuals. Community screening can help identify these individuals but is often too expensive for countries with limited health care resources. Low-cost ELISA assays may address this problem, but their use has not yet been widely reported. Methods We developed a SARS-CoV-2 nucleocapsid ELISA and assessed its diagnostic performance on nose and throat swab samples from UK hospitalised patients and sputum samples from patients in Ghana. Results The ELISA had a limit of detection of 8.4 pg/ml antigen and 16 pfu/ml virus. When tested on UK samples (128 positive and 10 negative patients), sensitivity was 58.6% (49.6-67.2) rising to 78.3% (66.7-87.3) if real-time PCR Ct values > 30 were excluded, while specificity was 100% (69.2-100). In a second trial using the Ghanaian samples (121 positive, 96 negative), sensitivity was 52% (42.8-61.2) rising to 72.6% (61.8-81.2) when a > 30 Ct cut-off was applied, while specificity was 100% (96.2-100). Conclusions: Our data show that nucleocapsid ELISAs can test a variety of patient sample types while achieving levels of sensitivity and specificity required for effective community screening. Further investigations into the opportunities that this provides are warranted.