Antimicrobial TiO2 nanocomposite coatings for surfaces, dental and orthopaedic implants.

Engineering of self-disinfecting surfaces to constrain the spread of SARS-CoV-2 is a challenging task for the scientific community because the human coronavirus spreads through respiratory droplets. Titania (TiO2) nanocomposite antimicrobial coatings is one of the ideal remedies to disinfect pathogens (virus, bacteria, fungi) from common surfaces under light illumination. The photocatalytic disinfection efficiency of recent TiO2 nanocomposite antimicrobial coatings for surfaces, dental and orthopaedic implants are emphasized in this review. Mostly, inorganic metals (e.g. copper (Cu), silver (Ag), manganese (Mn), etc), non-metals (e.g. fluorine (F), calcium (Ca), phosphorus (P)) and two-dimensional materials (e.g. MXenes, MOF, graphdiyne) were incorporated with TiO2 to regulate the charge transfer mechanism, surface porosity, crystallinity, and the microbial disinfection efficiency. The antimicrobial activity of TiO2 coatings was evaluated against the most crucial pathogenic microbes such as Escherichia coli, methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis, Legionella pneumophila, Staphylococcus aureus, Streptococcus mutans, T2 bacteriophage, H1N1, HCoV-NL63, vesicular stomatitis virus, bovine coronavirus. Silane functionalizing agents and polymers were used to coat the titanium (Ti) metal implants to introduce superhydrophobic features to avoid microbial adhesion. TiO2 nanocomposite coatings in dental and orthopaedic metal implants disclosed exceptional bio-corrosion resistance, durability, biocompatibility, bone-formation capability, and long-term antimicrobial efficiency. Moreover, the commercial trend, techno-economics, challenges, and prospects of antimicrobial nanocomposite coatings are also discussed briefly.

High-intensity focused ultrasound in the treatment of solid tumours.

Traditionally, surgery has been the only cure for many solid tumours. Technological advances have catalysed a shift from open surgery towards less invasive techniques. Laparoscopic surgery and minimally invasive techniques continue to evolve, but for decades high-intensity focused ultrasound has promised to deliver the ultimate objective - truly non-invasive tumour ablation. Only now, however, with recent improvements in imaging, has this objective finally emerged as a real clinical possibility.

Cytotoxic effects induced by unmodified and organically modified nanoclays in the human hepatic HepG2 cell line.

The term 'nanoclay' generically refers to the natural clay mineral, montmorillonite, with silica and alumina as the dominant constituents. The incorporation of nanoclays into polymeric systems dramatically enhances their barrier properties as well as their thermal and mechanical resistance. Consequently, nanoclays are employed in a wide range of industrial applications with recent studies reporting potential use in the modulation of drug release. With the increase in manufacturing of nanoclay-containing products, information on the toxicological and health effects of nanoclay exposure is warranted. Thus, the objective of the present study was to evaluate the cytotoxicity of two different nanoclays: the unmodified nanoclay, Cloisite Na+ ®, and the organically modified nanoclay, Cloisite 93A®, in human hepatoma HepG2 cells. Following 24 h exposure the nanoclays significantly decreased cell viability. Cloisite Na+ induced intracellular reactive oxygen species (ROS) formation which coincided with increased cell membrane damage, whilst ROS generation did not play a role in Cloisite 93A-induced cell death. Neither of the nanoclays induced caspase-3/7 activation. Moreover, in the cell culture medium the nanoclays aggregated differently and this appeared to have an effect on their mechanisms of toxicity. Taken together, our data demonstrate that nanoclays are highly cytotoxic and as a result pose a possible risk to human health.

Development of a novel porous cryo-foam for potential wound healing applications.

This body of work describes the development of a porous hydrogel for wound healing applications. In the present study poly (vinyl alcohol) (PVA) and poly (acrylic acid) (PAA) based hydrogels were prepared, and their properties were examined. Varying concentrations of the polymers and distilled water were used to prepare the hydrogels. The use of a high shear mixer, for foaming the PVA and PVA/PAA gels, and how this physical change can affect the structure and porosity of the hydrogel in question, represents a key feature of this work. The mechanical and thermal properties were determined by parallel plate rheometry and modulated differential scanning calorimetry (MDSC) respectively. The results indicated that the hydrogels containing low concentration of PVA and high volume of H(2)O are significantly weaker than those synthesised with higher concentrations of PVA. The thermal analysis shows distinct endotherms and provides evidence of crystallisation. The chemical structure of the hydrogels was confirmed by means of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR).

Characterisation and controlled drug release from novel drug-loaded hydrogels.

Hydrogel based devices belong to the group of swelling controlled drug delivery systems. Temperature responsive poly(N-isopropylacrylamide)-poly(vinylpyrrolidinone) random copolymers were produced by free radical polymerisation, using 1-hydroxycyclohexylphenyketone as an ultraviolet-light sensitive initiator, and poly(ethylene glycol) dimethacrylate as the crosslinking agent (where appropriate). The hydrogels were synthesised to have lower critical solution temperatures (LCST) near body temperature, which is favourable particularly for 'smart' drug delivery applications. Two model drugs (diclofenac sodium and procaine HCl) were entrapped within these xerogels, by incorporating the active agents prior to photopolymerisation. The properties of the placebo samples were contrasted with the drug-loaded copolymers at low levels of drug integration. Modulated differential scanning calorimetry (MDSC), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and atomic force microscopy (AFM) were used to investigate the influence of the drugs incorporated on the solid-state properties of the xerogels. MDSC and swelling studies were carried out to ascertain their effects on the LCST and swelling behaviour of the hydrated samples. In all cases, drug dissolution analysis showed that the active agent was released at a slower rate at temperatures above the phase transition temperature. Finally, preliminary in vitro cytotoxicity evaluations were performed to establish the toxicological pattern of the gels.

Preparation of monolithic matrices for oral drug delivery using a supercritical fluid assisted hot melt extrusion process.

The use of supercritical fluids as plasticisers in polymer processing has been well documented. The body of work described in this research paper outlines the use of a supercritical CO(2) assisted extrusion process in the preparation of a hot melt extruded monolithic polymer matrix for oral drug delivery. Several batches of matrix material were prepared with Carvedilol used as the active pharmaceutical ingredient (API). These batches were subsequently extruded both with and without supercritical CO(2) incorporation. The resultant matrices were characterised using steady-state parallel plate rheometry, differential scanning calorimetry (DSC), atomic force microscopy (AFM), micro-thermal analysis (microTA) and dissolution testing. Dissolution analysis showed that the use of supercritical CO(2) during the extrusion process resulted in a faster dissolution of API when compared with unassisted extrusion. The supercritical CO(2) incorporation also resulted in reduced viscosity during processing, therefore allowing for quicker throughput and productivity. The results detailed within this paper indicate that supercritical fluid assisted hot melt extrusion is a viable enhancement to conventional hot melt extrusion for the production of monolithic dosage forms.

The Development of a Melt-Extruded Shellac Carrier for the Targeted Delivery of Probiotics to the Colon.

Hot melt extrusion (HME) is considered an efficient technique in developing solid molecular dispersions, and has been demonstrated to provide sustained, modified and targeted drug delivery resulting in improved bioavailability. However, most commercial enteric or pH-responsive polymers are relatively difficult to process or have high Glass Transition Temperature (Tg) values, making their use with temperature-sensitive drugs, probiotics or biologics not viable. Shellac is a natural thermoplastic, and after a review of current literature on the pharmaceutical HME process, a possible gap in the knowledge of the use of shellac to produce dosage forms by means of HME was identified. This work explores the possibility of SSB® 55 pharmaceutical-grade shellac as a melt-extrudable encapsulation polymer to entrap freeze-dried probiotic powder and to determine bacterial cell viability post-processing. Well-defined strands were produced from the physical mixture of shellac and Biocare® Bifidobacterium Probiotic. FTIR clarified that there are no significant interactions between the probiotic and polymer. All of the samples demonstrated less than 5% degradation over 24 h at pH of both 1.2 and 6.8. At pH 7.4, both loaded samples gave a similar dissolution trend with complete degradation achieved after 10-11 h. Following five-month storage, 57.8% reduction in viability was observed.

The use of agar as a novel filler for monolithic matrices produced using hot melt extrusion.

The use of filler materials in an extended release monolithic polymer matrix can lead to a vastly altered release profile for the active pharmaceutical ingredient. A range of excipients for use in monolithic matrices have been discussed in the literature. The body of work described in this research paper outlines the use of agar as a novel filler material in a hot melt extruded polymer matrix. Several batches of matrix material were prepared with Diclofenac sodium used as the active pharmaceutical ingredient (API). Agar and microcrystalline cellulose were used as the filler materials in varying ratios, to examine the effect of % filler content as well as filler type on the properties of the hot melt extruded matrix. The resultant extrudates were characterised using steady state parallel plate rheometry, differential scanning calorimetry (DSC) and dissolution testing. The rheometry analysis concluded that the fillers used resulted in an increase in the matrix viscosity. The DSC scans obtained showed negligible effects on the melting behavior of the matrix as a result of the filler inclusion. Dissolution analysis showed that the presence of the fillers resulted in a slower release rate of API than for the matrix alone. The results detailed within this paper indicate that agar is a viable filler for extended release hot melt produced dosage forms.

Multifunctional polyvinylpyrrolidinone-polyacrylic acid copolymer hydrogels for biomedical applications.

Copolymers of N-vinylpyrrolidinone and acrylic acid, crosslinked with ethylene glycol dimethacrylate and polyethylene glycol 600 dimethacrylate were prepared by UV-polymerisation. These polymers were analysed for their extractable content by Soxhlet extraction of the samples at 100 degrees C for 72 h. Aspirin and paracetamol were incorporated into the polymer structure at 25 wt.% during the curing process and their presence confirmed by Fourier transform infrared spectroscopy. It was found that the release rate of the drug from the polymer matrix was dependent on intermolecular bonding between the polymer and active agent with aspirin being released slower than paracetamol in all cases. Results showed that paracetamol was completely released after 24h whereas complete release of aspirin took up to 70 h. Finally preliminary in vitro biocompatibility testing was performed for crosslinked polyvinylpyrrolidinone, by determining human hepatoma HepG2 cell viability in the MTT assay and DNA damage in the comet assay following direct contact with various concentrations of polyvinylpyrrolidinone-containing media. Cytotoxicity data suggests a dose-dependent effect for both crosslinkers, with concentrations in the range 0.025-2.5 mg ml(-1) showing a marginal decrease in viability to, at most, 70% that of untreated cells. Again DNA migration in the comet assay following short-term exposure to EGDMA crosslinked hydrogels correlates with MTT data.

Prevalence of Escherichia coli O157:H7 and indicator organisms on the surface of intact subprimal beef cuts prior to further processing.

The objective of this study was to determine the prevalence of Escherichia coli O157:H7, other E. coli strains, total coliforms, and aerobic organisms on the surface of subprimal beef cuts prior to enhancement. Subprimal cuts were sampled during winter (January and February 2004) and summer (August through October 2004). During each collection period, six representative subprimal cuts (chuck tenders, 0.64-cm trimmed strips, bottom round flat, rough-trimmed brisket, cap-on top rounds, and cap-off insides) were sampled. A total of 600 samples in winter (100 samples per cut) and 599 samples in summer (100 chuck tenders, 100 0.64-cm trimmed strips, 100 bottom round flats, 100 cap-off insides, 97 rough-trimmed briskets, and 102 cap-on top rounds) were collected from five plants in the Midwest, southern Midwest, northern Midwest, and Southeast and swabbed using the sponge swab method. All sponges were analyzed for E. coli O157:H7. In addition, 400 subprimal cuts from four plants were analyzed for aerobic plate counts, total coliforms, and other E. coli strains during each collection period. E. coli O157:H7 was not detected on any of the 1,199 subprimal samples; thus, incidence of E. coli O157:H7 was < 0.083%. Seasonal differences between aerobic plate counts and total coliform counts for each of the same cuts were 1.0 log CFU per cut or less. E. coli strains were not detected in 82, 52, 69, and 82% of the chuck tenders, 0.64-cm trimmed strips, bottom round flats, and cap-off insides, respectively.

High-intensity focused ultrasound principles, current uses, and potential for the future.

High-intensity focused ultrasound (HIFU) continues to be a very attractive option for minimally invasive procedures. Using well-established principles, this ablative therapy can be used to treat a number of benign and malignant diseases with few side effects. During the last 15 years, there has been an enormous amount of work, both laboratory based and in the form of clinical trials, aimed at developing devices that can deliver treatments with safe and effective outcomes. In this article, we aim to outline the principles of HIFU, describe the current commercially available machines and their applications, and discuss the role of HIFU in the future.

An evaluation of the biocompatibility properties of a salt-modified polyvinyl alcohol hydrogel for a knee meniscus application.

The treatment of irreparable knee meniscus tears remains a major challenge for the orthopaedic community. The main purpose of this research was to analyse the biocompatibility properties of a salt-modified polyvinyl alcohol hydrogel, in order to assess its potential for use as an artificial meniscal implant. Aqueous polyvinyl alcohol was treated with a sodium sulphate solution to precipitate out the polyvinyl alcohol resulting in a pliable hydrogel. Cytotoxicological analysis indicates that PVA/sodium sulphate hydrogels display a non-toxic disposition and were found to be compatible with the L929 fibroblast cell line.

Gluteus medius coactivation response in field hockey players with and without low back pain.

OBJECTIVES: To examine the effect of prolonged standing on gluteus medius coactivation and to observe whether the changes in gluteus medius coactivation over time were related to the development of low back pain in elite female field hockey players. DESIGN: Prospective cohort design. METHODS: Participants were 39 elite female field hockey players (14 with a history of low back pain). Before the prolonged stand, maximal hip abduction strength, side bridge hold endurance and hip abduction range of motion were measured bilaterally. Surface electromyography was collected from the gluteus medius for coactivation analysis during a prolonged stand for 70 min. Low back pain was rated every 10 min on a visual analogue scale. RESULTS: Fourteen of 39 participants developed low back pain. The Time effect was significant for gluteus medius coactivation response (p = 0.003) and visual analogue scale score (p < 0.001). There were no significant group × time interactions. Yet athletes who developed pain had higher coactivation for the majority of the stand task. CONCLUSIONS: While female field hockey players have high agonist-antagonist coactivation patterns during prolonged standing, stand task is a useful tool to predict low back pain occurrence in players with and without history of pain.

Biomechanical analysis of a salt-modified polyvinyl alcohol hydrogel for knee meniscus applications, including comparison with human donor samples.

The primary objective of this research was the biomechanical analysis of a salt-modified polyvinyl alcohol hydrogel, in order to assess its potential for use as an artificial meniscal implant. Aqueous polyvinyl alcohol (PVA) was treated with a sodium sulphate (Na2SO4) solution to precipitate out the polyvinyl alcohol resulting in a pliable hydrogel. The freeze-thaw process, a strictly physical method of crosslinking, was employed to crosslink the hydrogel. Development of a meniscal shaped mould and sample housing unit allowed the production of meniscal shaped hydrogels for direct comparison to human meniscal tissue. Results obtained show that compressive responses were slightly higher in PVA/Na2SO4 menisci, displaying maximum compressive loads of 2472N, 2482N and 2476N for samples having undergone 1, 3 and 5 freeze-thaw cycles respectively. When compared to the human meniscal tissue tested under the same conditions, an average maximum load of 2467.5N was observed. This suggests that the PVA/Na2SO4 menisci are mechanically comparable to the human meniscus. Biocompatibility analysis of PVA/Na2SO4 hydrogels revealed no acute cytotoxicity. The work described herein has innovative potential in load bearing applications, specifically as an alternative to meniscectomy as replacement of critically damaged meniscal tissue in the knee joint where repair is not viable.

Contrast-enhanced ultrasound assessment of tissue response to high-intensity focused ultrasound.

We report the use of contrast-enhanced ultrasonography as an immediate means of assessing the clinical response to high-intensity focused ultrasound (US) or HIFU treatment of liver tumours. HIFU is a noninvasive transcutaneous technique for the ablation of tumours that has been shown to destroy tumour vasculature, as well as to cause coagulative necrosis of tumour cells. As a dynamic indicator of tissue perfusion, microbubble contrast agents have already been reported to increase the diagnostic sensitivity of ultrasonography in the detection of liver tumours. This report documents the ability of one i.v. microbubble contrast agent (SonoVue, Bracco, Italy) to delineate the extent of HIFU ablation by comparison of pre- and immediately posttreatment perfusion within the target tumour. Observed changes were seen to correlate well with the ablated volume on histologic evaluation of the treated volume. This is the first time that this imaging technique has been reported in this setting.

Changes in spirituality and well-being in a retreat program for cardiac patients.

CONTEXT: Many epidemiological studies indicate that spirituality or religion are positively correlated with health measures, but research is needed on interventions that change spirituality to verify that it actually affects health and to justify suggestions that changes in spiritual practices or beliefs may have health benefits. However, it is not clear that health interventions can influence spirituality or which techniques are effective. OBJECTIVE: To evaluate whether participation in a retreat program for cardiac patients and their partners resulted in changes in spirituality and whether changes in spirituality were related to changes in well-being meaning in life, anger, and confidence in handling problems. DESIGN: Participants filled out questionnaires before and after participating in the retreat. SETTING: Retreats were sponsored by the Health Promotion and Wellness Program, University of Wisconsin-Stevens Point, and were held in a remote training center. PARTICIPANTS: Notices were sent to cardiac rehabilitation programs and directly to heart patients, resulting in the enrollment of 72 first-time participants. INTERVENTION: The 2.5-day educational retreats included discussion and opportunities to experience healthy lifestyle options. Exercise, nutrition, stress management techniques, communication skills that enhance social support, and spiritual principles of healing were incorporated. Experiential practices included yoga, meditation, visualization, and prayer. RESULTS: Of the participants, 78% reported increased spirituality after the retreat. Changes in spirituality were positively associated with increased well-being meaning in life, confidence in handling problems, and decreased tendency to become angry. CONCLUSIONS: Programs that explore spirituality in a health context can result in increased spirituality that is associated with increased well-being and related measures. Many patients and their families want to integrate the spiritual and health dimensions of their lives. Further work is needed to develop healthcare settings that can support this integration.

A pilot study of risk-based prevention in private practice.

BACKGROUND: Risk-based prevention is a means of ensuring that patients receive preventive treatment appropriate for their risk of disease. While straightforward, its application in private practice has not been examined. METHODS: Volunteer clinicians in 15 offices participated in a six-month pilot study to test methods for a larger, risk-based prevention demonstration study operated by a dental insurer. Concomitant with oral examinations for patients of this insurer, clinicians identified patients at elevated risk of developing dental caries and periodontitis. For these patients, the reasons for elevated risk (risk indicators), as well as planned preventive treatment in response to that risk, were recorded and transmitted to the insurer via the claim form. RESULTS: The clinicians identified relatively small percentages of patients as being at high risk of developing caries (4 percent) and periodontitis (7 percent), with little variation across the 15 offices. Larger proportions of patients were identified as being at moderate risk of developing caries (29 percent) and periodontitis (30 percent), with more extensive variation across offices. In general, patients classified as being at elevated risk had received more disease-related treatment than patients at low risk before the classification, which provided some validation for the accuracy of risk assessment. CONCLUSIONS: The results of this pilot study suggest that formal, risk-based prevention can be accomplished in dental offices. Clinicians' reported risk assignments and indicators, together with their planned preventive treatments, demonstrate a good understanding of risk-based prevention. CLINICAL IMPLICATIONS: Researchers may need to clarify the criteria used to assess moderate risk of developing dental caries, and clinicians may need to emphasize greater use of fluorides and more frequent recall visits for adults at elevated risk of developing dental caries.

An evaluation of the thermal and mechanical properties of a salt-modified polyvinyl alcohol hydrogel for a knee meniscus application.

The treatment of irreparable knee meniscus tears remains a major challenge for the orthopaedic community. The main purpose of this research was to analyse the mechanical properties and thermal behaviour of a salt-modified polyvinyl alcohol hydrogel, in order to assess its potential for use as an artificial meniscal implant. Aqueous poly vinyl alcohol was treated with a sodium sulphate solution to precipitate out the polyvinyl alcohol resulting in a pliable hydrogel. The freeze-thaw process, a strictly physical method of crosslinking, was employed to crosslink the hydrogel. Physical crosslinks in the form of crystalline regions were induced within the hydrogel structure which resulted in a large increase in mechanical resistance. Results showed that the optimal sodium sulphate addition of 6.6% (w/v) Na2SO4 in 8.33% (w/v) PVA causes the PVA to precipitate out of its solution. The effect of multiple freeze thaw cycles was also investigated. Investigation comprised of a variety of well-established characterisation techniques such as differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), mechanical analysis, rheometry and swelling studies. DSC analysis showed that samples cross-linked using the freeze thaw process display a thermal shift due to increased crosslink density. FTIR analysis confirmed crystallisation is present at 1142cm(-1) and also showed that no chemical alteration occurs when PVA is treated with sodium sulphate. Swelling studies indicated that that PVA/sodium sulphate hydrogels absorb less water than untreated hydrogels due to increased amounts of PVA present. Compressive strength analysis of PVA/sodium sulphate hydrogels prepared at -80°C displayed average maximum loads of 2472N, 2482.4N and 2476N of over 1, 3 and 5 freeze thaw cycles respectively. Mechanical analysis of the hydrogel indicated that the material is thermally stable and resistant to breakdown by compressive force. These properties are crucial for potential use as a meniscus or cartilage replacement. As such, the results of this study indicate that polyvinyl alcohol modified with sodium sulphate may be a suitable material for the construction of an artificial knee meniscus.

Effects of temperature, packaging and electron beam irradiation processing conditions on the property behaviour of Poly (ether-block-amide) blends.

The radiation stability of Poly (ether-block-amide) (PEBA) blended with a multifunctional phenolic antioxidant and a hindered amide light stabiliser was examined under various temperatures, packaging and electron beam processing conditions. FTIR revealed that there were slight alterations to the PEBA before irradiation; however, these became more pronounced following irradiation. The effect of varying the temperature, packaging and processing conditions on the resultant PEBA properties was apparent. For example, rheology demonstrated that the structural properties could be enhanced by manipulating the aforementioned criteria. Mechanical testing exhibited less radiation resistance when the PEBA samples were vacuum packed and exposed to irradiation. MFI and AFM confirmed that the melting strength and surface topography could be reduced/increased depending on the conditions employed. From this study it was concluded that virgin PEBA submerged in dry ice with non-vacuum packaging during the irradiation process, provided excellent radiation resistance (20.9% improvement) in contrast to the traditional method.

Effects of gamma ray and electron beam irradiation on the mechanical, thermal, structural and physicochemical properties of poly (ether-block-amide) thermoplastic elastomers.

Both gamma ray and electron beam irradiation are widely used as a means of medical device sterilisation. However, it is known that the radiation produced by both processes can lead to undesirable changes within biomedical polymers. The main objective of this research was to conduct a comparative study on the two key radiosterilisation methods (gamma ray and electron beam) in order to identify the more detrimental process in terms of the mechanical, structural, chemical and thermal properties of a common biomedical grade polymer. Poly (ether-block-amide) (PEBA) was prepared by injection moulding ASTM testing specimens and these were exposed to an extensive range of irradiation doses (5-200 kGy) in an air atmosphere. The effect of varying the irradiation dose concentration on the resultant PEBA properties was apparent. For instance, the tensile strength, percentage elongation at break and shore D hardness can be increased/decreased by controlling the aforementioned criteria. In addition, it was observed that the stiffness of the material increased with incremental irradiation doses as anticipated. Melt flow index demonstrated a dramatic increase in the melting strength of the material indicating a sharp increase in molecular weight. Conversely, modulated differential scanning calorimetry established that there were no significant alterations to the thermal transitions. Noteworthy trends were observed for the dynamic frequency sweeps of the material, where the crosslink density increased according to an increase in electron beam irradiation dose. Trans-vinylene unsaturations and the carbonyl group concentration increased with an increment in irradiation dose for both processes when observed by FTIR. The relationship between the irradiation dose rate, mechanical properties and the subsequent surface properties of PEBA material is further elucidated throughout this paper. This study revealed that the gamma irradiation process produced more adverse effects in the PEBA material in contrast to the electron beam irradiation process.