Search

BACKGROUND: Current methods used for the detection of residual proteinaceous contamination vary in sensitivity and specificity. This is of concern because it increases the risk for transmission of neurodegenerative diseases such as spongiform encephalopathies. AIM: To determine the effectiveness of electrolysis-assisted sonication (EAS) for removing residual proteinaceous contamination from surgical grade stainless steel. METHODS: EAS was used to clean surgical grade 316L stainless steel that had been contaminated with the protein bovine serum albumin. Using nitrogen, an abundant element in proteins, as a marker for the presence of protein, X-ray photoelectron spectroscopy (XPS) was used to quantify the amount of protein remaining on the substrate surface. Cathodic, anodic and dual polarization modes of EAS were investigated using 0.1% NaCl solution (w/v, in deionized water) as the electrolyte medium and 13 V as the polarization voltage. FINDING: EAS under dual polarization was found to be the most effective method for removing the residual protein layer down to an estimated XPS detection limit of 10 ng/cm(2). Surface roughness and hardness of the stainless steel remained unchanged following EAS treatment, indicating that the procedure does not compromise the material's properties. CONCLUSION: This relatively inexpensive and quick method of cleaning medical devices using an easily accessible salt-based electrolyte solution may offer a cost-effective strategy for cleaning medical and dental devices made of stainless steel in the future. [ABSTRACT FROM AUTHOR]

High-grade serous ovarian cancer (HGSOC) is the most common and aggressive type of ovarian cancer. Due to a lack of an early detection test and overt symptoms, many patients are diagnosed at a late stage where metastasis makes treatment very challenging. Furthermore, the current standard treatment for HGSOC patients, consisting of debulking surgery and platinum-taxane chemotherapy, reduces quality of life due to debilitating side-effects. Sadly, 80-90% of patients diagnosed with advanced stage ovarian cancer will die due to treatment resistance. As such, novel therapeutic strategies for HGSOC that are both more effective and less toxic are urgently required. Here we describe the assessment of cold atmospheric pressure (CAP) gas discharge technology as a novel treatment strategy in pre-clinical models of HGSOC. Plasma-activated media (PAM) was generated using cell growth media. HGSOC cell lines, patient ascites cells and primary tissue explants were tested for their response to PAM via analysis of cell viability, cell death and oxidative stress assays. Our data show that PAM treatment can be more effective than standard carboplatin chemotherapy at selectively targeting ovarian cancer cells in primary patient samples. Further, we also observed PAM to induce apoptosis in HGSOC cancer cell lines via induction of oxidative stress and mitochondrial-mediated apoptosis. These findings suggest that PAM is a viable therapeutic strategy to test in in vivo models of ovarian cancer, with a view to develop an intraperitoneal PAM-based therapy for HGSOC patients. Our studies validate the ability of PAM to selectively target tumour tissue and ascites cells. This work supports the development of PAM towards in vivo validation and translation into clinical practice., (© 2024 The Author(s). Molecular Oncology published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)

Chronic wound infections are a silent pandemic in danger of becoming a global healthcare crisis. Innovations to control infections and improve healing are required. In the context of this challenge, researchers are exploiting plasma-activated hydrogel therapy (PAHT) for use either alone or in combination with other antimicrobial strategies. PAHT involves the cold atmospheric pressure plasma activation of hydrogels with reactive oxygen and nitrogen species to decontaminate infections and promote healing. This opinion article describes PAHT for wound treatment and provides an overview of current research and outstanding challenges in translating the technology for medical use. A 'blueprint' of an autonomous PAHT is presented in the final section that can move the management and treatment of wounds from the clinical setting to the community., Competing Interests: Declaration of interests R.D.S. and E.J.S. are founders of the company Plasma4 and are inventors on patent WO2015123720A1., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Low temperature plasma technology is proving to be at the frontier of emerging medical technologies with real potential to overcome escalating healthcare challenges including antimicrobial and anticancer resistance. However, significant improvements in efficacy, safety, and reproducibility of plasma treatments need to be addressed to realize the full clinical potential of the technology. To improve plasma treatments recent research has focused on integrating automated feedback control systems into medical plasma technologies to maintain optimal performance and safety. However, more advanced diagnostic systems are still needed to provide data into feedback control systems with sufficient levels of sensitivity, accuracy, and reproducibility. These diagnostic systems need to be compatible with the biological target and to also not perturb the plasma treatment. This paper reviews the state-of-the-art electronic and optical sensors that might be suitable to address this unmet technological need, and the steps needed to integrate these sensors into autonomous plasma systems. Realizing this technological gap could facilitate the development of next-generation medical plasma technologies with strong potential to yield superior healthcare outcomes.

Advances in digital technologies have opened new opportunities for creating more reliable, time- and cost-effective, safer and mobile methods of diagnosing, managing and treating diseases. A few examples of advanced nano- and digital technologies are already FDA-approved for diagnosing and treating diseases. Plasma treatment is still emerging as a new healthcare technology, but it is showing a strong potential for treatment of many diseases including cancers and antimicrobial-resistant infections, with little or no adverse side effects. Here, we argue that with the ever-increasing complex healthcare challenges facing communities, including the ongoing COVID-19 pandemic, it is critical to consider combining unique properties of emerging healthcare technologies into a single multimodal treatment modality that could lead to unprecedented healthcare benefits. In this article, we focus on the healthcare opportunities created by establishing a nexus between plasma, nano- and digital technologies. We argue that the combination of plasma, nano- and digital technologies into a single multimodal healthcare package may significantly improve patient outcomes and comfort, and reduce the economic burden on community healthcare, as well as alleviate many problems related to overcrowded healthcare systems., (© 2020 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.)

The mechanisms of plasma in medicine are broadly attributed to plasma-derived reactive oxygen and nitrogen species (RONS). In order to exert any intracellular effects, these plasma-derived RONS must first traverse a major barrier in the cell membrane. The cell membrane lipid composition, and thereby the magnitude of this barrier, is highly variable between cells depending on type and state (e.g. it is widely accepted that healthy and cancerous cells have different membrane lipid compositions). In this study, we investigate how plasma-derived RONS interactions with lipid membrane components can potentially be exploited in the future for treatment of diseases. We couple phospholipid vesicle experiments, used as simple cell models, with molecular dynamics (MD) simulations of the lipid membrane to provide new insights into how the interplay between phospholipids and cholesterol may influence the response of healthy and diseased cell membranes to plasma-derived RONS. We focus on the (i) lipid tail saturation degree, (ii) lipid head group type, and (iii) membrane cholesterol fraction. Using encapsulated molecular probes, we study the influence of the above membrane components on the ingress of RONS into the vesicles, and subsequent DNA damage. Our results indicate that all of the above membrane components can enhance or suppress RONS uptake, depending on their relative concentration within the membrane. Further, we show that higher RONS uptake into the vesicles does not always correlate with increased DNA damage, which is attributed to ROS reactivity and lifetime. The MD simulations indicate the multifactorial chemical and physical processes at play, including (i) lipid oxidation, (ii) lipid packing, and (iii) lipid rafts formation. The methods and findings presented here provide a platform of knowledge that could be leveraged in the development of therapies relying on the action of plasma, in which the cell membrane and oxidative stress response in cells is targeted.

Electrically generated cold atmospheric plasma is being intensively researched for novel applications in biology and medicine. Significant attention is being given to reactive oxygen and nitrogen species (RONS), initially generated upon plasma-air interactions, and subsequently delivered to biological systems. Effects of plasma exposure are observed to millimeter depths within tissue. However, the exact nature of the initial plasma-tissue interactions remains unknown, including RONS speciation and delivery depth, or how plasma-derived RONS intervene in biological processes. Herein, we focus on current research using tissue and cell models to learn more about the plasma delivery of RONS into biological environments. We argue that this research is vital in underpinning the knowledge required to realize the full potential of plasma in biology and medicine., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Chronic wounds are a major socio-economic problem. Bacterial infections in such wounds are a major contributor to lack of wound healing. An early indicator of wound infection is an increase in pH of the wound fluid. Herein, we describe the development of a pH-responsive drug delivery device that can potentially be used for wound decontamination in situ and on-demand in response to an increase in the pH of the wound environment. The device is based on a porous silicon film that provides a reservoir for encapsulation of an antibiotic within the pores. Loaded porous silicon is capped with dual plasma polymer layers of poly(1,7-octadiene) and poly(acrylic acid), which provide a pH-responsive barrier for on-demand release of the antibiotic. We demonstrate that release of the antibiotic is inhibited in aqueous buffer at pH 5, whereas the drug is released in a sustainable manner at pH 8. Importantly, the released drug was bacteriostatic against the Pseudomonas aeruginosa wound pathogen. In the future, incorporation of the delivery device into wound dressings could potentially be utilized for non-invasive decontamination of wounds., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Despite growing interest in the application of atmospheric plasma jets as medical treatment strategies, there has been comparatively little research on the potential genotoxic and cytotoxic effects of plasma jet treatment. In this study, we have employed the cytokinesis block micronucleus cytome (CBMN-Cyt) assay with WIL2-NS B lymphoblastoid cells to test the potential genotoxicity, as well as the cytotoxicity, of toxic species generated in cell culture media by an argon (Ar) plasma jet. Elevated levels of cell death (necrosis) and occurrence of chromosomal damage (micronuclei MN, nculeoplasmic bridge NPBs and nuclear bus, Nbuds) were observed when cells were exposed to plasma jet-treated media. These results provide a first insight into how we might measure the genotoxic and cytotoxic effect of plasma jet treatments (both indirect and direct) in dividing human cells.

This paper reports on the fabrication of a pSi-based drug delivery system, functionalized with an initiated chemical vapor deposition (iCVD) polymer film, for the sustainable and temperature-dependent delivery of drugs. The devices were prepared by loading biodegradable porous silicon (pSi) with a fluorescent anticancer drug camptothecin (CPT) and coating the surface with temperature-responsive poly(N-isopropylacrylamide-co-diethylene glycol divinyl ether) (pNIPAM-co-DEGDVE) or non-stimulus-responsive poly(aminostyrene) (pAS) via iCVD. CPT released from the uncoated oxidized pSi control with a burst release fashion (∼21 nmol/(cm(2) h)), and this was almost identical at temperatures both above (37 °C) and below (25 °C) the lower critical solution temperature (LCST) of the switchable polymer used, pNIPAM-co-DEGDVE (28.5 °C). In comparison, the burst release rate from the pSi-pNIPAM-co-DEGDVE sample was substantially slower at 6.12 and 9.19 nmol/(cm(2) h) at 25 and 37 °C, respectively. The final amount of CPT released over 16 h was 10% higher at 37 °C compared to 25 °C for pSi coated with pNIPAM-co-DEGDVE (46.29% vs 35.67%), indicating that this material can be used to deliver drugs on-demand at elevated temperatures. pSi coated with pAS also displayed sustainable drug delivery profiles, but these were independent of the release temperature. These data show that sustainable and temperature-responsive delivery systems can be produced by functionalization of pSi with iCVD polymer films. Benefits of the iCVD approach include the application of the iCVD coating after drug loading without causing degradation of the drug commonly caused by exposure to factors such as solvents or high temperatures. Importantly, the iCVD process is applicable to a wide array of surfaces as the process is independent of the surface chemistry and pore size of the nanoporous matrix being coated.

The transport of plasma generated reactive oxygen species (ROS) across a simple phospholipid membrane mimic of a (real) cell was investigated. Experiments were performed in cell culture media (Dulbecco's modified Eagle's medium, DMEM), with and without 10% serum. A (broad spectrum) ROS reporter dye, 2,7-dichlorodihydrofluorescein (DCFH), was used to detect the generation of ROS by a helium (He) plasma jet in DMEM using free DCFH and with DCFH encapsulated inside phospholipid membrane vesicles dispersed in DMEM. The authors focus on the concentration and on the relative rates (arbitrary units) for oxidation of DCFH [or the appearance of the oxidized product 2,7-dichlorofluorescein (DCF)] both in solution and within vesicles. In the first 1 h following plasma exposure, the concentration of free DCF in DMEM was ~15× greater in the presence of serum (cf. to the serum-free DMEM control). The DCF in vesicles was ~2× greater in DMEM containing serum compared to the serum-free DMEM control. These data show that serum enhances plasma ROS generation in DMEM. As expected, the role of the phospholipid membrane was to reduce the rate of oxidation of the encapsulated DCFH (with and without serum). And the efficiency of ROS transport into vesicles was lower in DMEM containing serum (at 4% efficiency) when compared to serum-free DMEM (at 32% efficiency). After 1 h, the rate of DCFH oxidation was found to have significantly reduced. Based upon a synthesis of these data with results from the open literature, the authors speculate on how the components of biological fluid and cellular membranes might affect the kinetics of consumption of plasma generated ROS.

Spatially varied surface treatment of a fluorescently labeled Bovine Serum Albumin (BSA) protein, on the walls of a closed (sealed) microchannel is achieved via a well-defined gradient in plasma intensity. The microchips comprised a microchannel positioned in-between two microelectrodes (embedded in the chip) with a variable electrode separation along the length of the channel. The channel and electrodes were 50 μm and 100 μm wide, respectively, 50 μm deep, and adjacent to the channel for a length of 18 mm. The electrode separation distance was varied linearly from 50 μm at one end of the channel to a maximum distance of 150, 300, 500, or 1000 μm to generate a gradient in helium plasma intensity. Plasma ignition was achieved at a helium flow rate of 2.5 ml/min, 8.5 kVpk-pk, and 10 kHz. It is shown that the plasma intensity decreases with increasing electrode separation and is directly related to the residual amount of BSA left after the treatment. The plasma intensity and surface protein gradient, for the different electrode gradients studied, collapse onto master curves when plotted against electrode separation. This precise spatial control is expected to enable the surface protein gradient to be tuned for a range of applications, including high-throughput screening and cell-biomolecule-biomaterial interactions.

We describe a pH responsive drug delivery system which was fabricated using a novel approach to functionalize biodegradeable porous silicon (pSi) by initiated chemical vapor deposition (iCVD). The assembly involved first loading a model drug (camptothecin, CPT) into the pores of the pSi matrix followed by capping the pores with a thin pH responsive copolymer film of poly(methacrylic acid-co-ethylene dimethacrylate) (p(MAA-co-EDMA)) via iCVD. Release of CPT from uncoated pSi was identical in two buffers at pH 1.8 and pH 7.4. In contrast, the linear release rate of CPT from the pSi matrix with the p(MAA-co-EDMA) coating was dependent on the pH; release of CPT was more than four times faster at pH 7.4 (13.1 nmol/(cm(2) h)) than at pH 1.8 (3.0 nmol/(cm(2) h)). The key advantage of this drug delivery approach over existing ones based on pSi is that the iCVD coating can be applied to the pSi matrix after drug loading without degradation of the drug because the process does not expose the drug to harmful solvents or high temperatures and is independent of the surface chemistry and pore size of the nanoporous matrix.

A rapid, high-precision method for localised plasma-treatment of bonded PDMS microchannels is demonstrated. Patterned electrodes were prepared by injection of molten gallium into preformed microchannel guides. The electrode guides were prepared without any additional fabrication steps compared to conventional microchannel fabrication. Alignment of the "injected" electrodes is precisely controlled by the photomask design, rather than positioning accuracy of alignment tools. Surface modification is detected using a fluorescent dye (Rhodamine B), revealing a well-defined micropattern with regions less than 100 µm along the length of the microchannel.

There is considerable interest in the highly parallelized mass spectrometry analysis of complex sample mixtures without any time-consuming prepurification. Porous silicon-based laser desorption/ionization mass spectrometry (pSi LDI-MS) is enabling technology for such analysis. Previous studies have focused on pSi surface functionalization to enhance sensitivity of detection and engineer surfaces for sample capture and enrichment in LDI-MS analysis. In this report, we build on this work by showing that surface functionalization of thin pSi films can be extended to the covalent immobilization of antibodies, producing a porous immunoaffinity surface. We demonstrate highly selective mass spectrometric detection of illicit drugs (benzodiazepines) on pSi films displaying antibenzodiazepine antibodies covalently immobilized via isocyanate chemistry. The effects of antibody immobilization conditions, antibody concentration, and surface blocking on LDI-MS performance and selectivity were studied. X-ray photoelectron spectroscopy (XPS) was instrumental in characterizing surface chemistry and optimizing LDI-MS performance. Overall, our approach is suitable for rapid and sensitive confirmatory analysis in forensic toxicology requiring only minimal sample volume and may be applied to other areas requiring small molecular analysis such as metabolomics and pharmacology.

Elastomeric polyesters synthesized from non-toxic and biocompatible reactants are topical research materials for tissue-engineering applications. In such applications, the morphology, chemistry and functionality of the materials surfaces play a key role. While a number of papers have focused and reported on the fabrication and biological evaluation of elastic polyesters, only a few have attempted to characterise the surfaces of such materials. In this paper, we report on the preparation and surface characterization of films of a co-polyester bioelastomer, polyoctanediol citrate/sebacate (p(OCS)). The co-polymer was synthesized following the standard procedure of polyesterification using three non-toxic monomers (1,8-octanediol, citric acid and sebacic acid) in a catalyst-free environment. Nuclear magnetic resonance spectroscopy was used to monitor the chemical composition of the various p(OCS) elastomers. The p(OCS) films, prepared by both spin-coating and solvent casting of the p(OCS) pre-polymer solutions, were characterized by scanning electron microscopy, UV-Vis titration, photo-acoustic Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, and tested for their cytocompatibility. The results obtained suggest that the surface morphology, chemistry and the concentration of the surface functional groups can be controlled by simply varying the initial acid concentration (citric/sebacic acids) in the pre-polymer. The films supported the attachment and proliferation of osteoblast-like cells (MG63). This unique approach provides an effective method of controlling and monitoring the fundamental p(OCS) surface properties important for their potential utilisation as a tissue-engineering material.

This work examines the biocompatibility of poly(octanediol citrate)/sebacate (p(OCS)) biodegradable polyester elastomers. The growth of human MG63 osteoblast-like cells was studied on p(OCS) films. Three types of p(OCS) films were synthesised simply by varying the concentrations of 1,8-octanediol (OD), citric acid (CA), and sebacic acid (SA) monomers at initial molar ratios of 1:1:0, 1:0.75:0.25 and 1:0.5:0.5. At these ratios, the p(OCS) films exhibit decreasing hydrophilicity as shown by the measured water contact angle values of 31, 41 and 64 degrees , respectively. For all the samples, no difference in cell growth was detected after 1 day of cell culture. However, after 4 days, the highest number of viable cells was detected on the p(OCS) film synthesised with the intermediate CA molar ratio of 0.75. This sample also contains the median concentration of surface carboxylic acid groups and hydrophilicity. Following long-term cell culture (18 days), a statistically significant higher density of viable cells had grown on the p(OCS) films with SA molar ratios of 0.25 (P < 0.0001) and 0.5 (P = 0.002) in comparison to the material containing 100% CA and no SA. The work demonstrated that the performance of possible p(OCS) bone tissue engineering scaffolds could be improved by simply adjusting the molar ratios of CA and SA in the pre-polymer without any requirements for post-synthesis modification.

Previously, we have developed and characterised a procedure for the deposition of thin silica films by a plasma enhanced chemical vapour deposition (PECVD) procedure using tetraethoxysilane (TEOS) as the main precursor. We have used the silica coatings for improving the corrosion resistance of metals and for enhancing the bioactivity of biomedical metallic implants. Recently, we have been fine-tuning the PECVD method for producing high quality and reproducible PECVD-silica (PECVD-Si) coatings on metals, primarily for biomaterial applications. In order to understand the interaction of the PECVD-Si coatings with biological species (such as proteins and cells), it is important to first analyse the properties of the silica films deposited using the optimised parameters. Therefore, this current investigation was carried out to analyse the characteristic features of PECVD-Si deposited on Ti substrates (PECVD-Si-Ti). We determined that the PECVD-Si coatings on Ti were conformal to the substrate surface, strongly adhered to the underlying substrate and were resistant to delamination. The PECVD-Si surface was composed of stoichiometric SiO(2), showed a low carbon content (below 10 at.%) and was very hydrophilic (contact angle <10°). Finally, we also showed that the PECVD-Si coatings contain functional hydroxyl groups.