Bacterial and fungal absorption properties of a hydrogel dressing with a superabsorbent polymer core

Anionic polyelectrolyte-regulated cellulose nanocrystal-based hydrogels for controllable drug release

The application of inorganic salt-regulated Hofmeister effects in cellulose nanocrystals (CNC)-based hydrogels is hindered by limitations, including poor biocompatibility and difficulties in achieving precise drug release. In this study, we show that the anionic polyelectrolyte regulated Hofmeister effect promotes the aggregation and crystallization of CNC and polyvinyl alcohol (PVA) chains. This structural transformation significantly enhances the controllability of drug release in CNC-based hydrogels. The incorporation of anionic polyelectrolytes into CNC-based hydrogels creates a semi-interpenetrating polymer network (semi-IPN), significantly enhancing their mechanical properties and improving in vitro drug release controllability. Our hydrogel exhibits significant flexibility in controlling both drug release duration and capacity, with adjustable release times ranging from 16 to 52 h and tunable drug release capacities between 10.13 mg/g and 19.21 mg/g. Furthermore, antibacterial and cytotoxicity assays confirm its favorable biocompatibility and moderate antibacterial properties. Overall, our research findings emphasize that the preparation of cellulose-based hydrogels using polyelectrolytes has certain flexible regulatory functions in drug release.

An observational study of wounds treated with hydro-responsive wound dressings

OBJECTIVE

Acute and hard-to-heal wounds are a significant burden to both a patient's quality of life and resources in healthcare systems. Here, we evaluate the outcomes of a non-comparative case series study in which Ringer's solution-preactivated polyacrylate dressings were used to treat acute and hard-to-heal wounds (the presence of Ringer's solution provides a wound dressing that allows, upon application, the immediate hydration of the underlying wound tissue).

METHOD

Patients with acute and hard-to-heal wounds were enrolled into an open-labelled, non-comparative observational study. Patients were treated with Ringer's solution-preactivated polyacrylate dressings to enable wound debridement and wound cleansing for up to 12 weeks.

RESULTS

A total of 303 patients were enrolled in the study and 278 were included in the analysis. Wound size decreased, from a median of 3.6cm² (interquartile range (IQR): 1.2-9.3] at baseline to a median of 2.6cm² (IQR: 1.1-7.8] at 84 days. Relative wound area reduction (WAR) was 43.1% at 84 days and estimated probability of achievement of a WAR of ≥40% and ≥60% was 68.7% and 53.4%, respectively. Median time to achieve a WAR of ≥40% and ≥60% was 54 days and 75 days, respectively. The median percentage of wound area covered by fibrin had decreased from 50.0% to 10% and granulation tissue had increased from 25% to 50% after 84 days. In addition, periwound skin condition, local signs of infection and pain all showed improvement. The majority of the wounds were assessed as 'healed' or 'better' at the conclusion of the evaluation period.

CONCLUSION

Based on the findings of this study, the use of Ringer's solution-preactivated polyacrylate dressings in daily practice has the potential to improve clinical outcomes, including healing, in patients with acute and hard-to-heal wounds.

Superabsorbent polymers: A state-of-art review on their classification, synthesis, physicochemical properties, and applications

Superabsorbent polymers (SAP) and modified natural polymer hydrogels are widely and increasingly used in agriculture, health care textiles, effluent treatment, drug delivery, tissue engineering, civil concrete structure, etc. However, not many comprehensive reviews are available on this class of novel polymers. A review covering all the viable applications of SAP will be highly useful for researchers, industry persons, and medical, healthcare, and agricultural purposes. Hence, an attempt has been made to review SAPs with reference to their classifications, synthesis, modification by crosslinking, and physicochemical characterization such as morphology, swellability, thermal and mechanical properties, lifetime prediction, thermodynamics of swelling, absorption, release and transport kinetics, quantification of hydrophilic groups, etc. Besides, the possible methods of fine-tuning their structures for improving their absorption capacity, fast absorption kinetics, mechanical strength, controlled release features, etc. were also addressed to widen their uses. This review has also highlighted the biodegradability, commercial viability and market potential of SAPs, SAP composites, the feasibility of using biomass as raw materials for SAP production, etc. The challenges and future prospects of SAP, their safety, and environmental issues are also discussed.

New Approach to Antifungal Activity of Fluconazole Incorporated into the Porous 6-Anhydro-α-l-Galacto-β-d-Galactan Structures Modified with Nanohydroxyapatite for Chronic-Wound Treatments-In Vitro Evaluation

New fluconazole-loaded, 6-Anhydro-α-l-Galacto-β-d-Galactan hydrogels incorporated with nanohydroxyapatite were prepared and their physicochemical features (XRD, X-ray Diffraction; SEM-EDS, Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy; ATR-FTIR, Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy), fluconazole release profiles and enzymatic degradation were determined. Antifungal activity of pure fluconazole was tested using Candida species (C. albicans, C. tropicalis, C. glabarata), Cryptococcus species (C. neoformans, C. gatti) and Rhodotorula species (R. mucilaginosa, R. rubra) reference strains and clinical isolates. Standard microdilution method was applied, and fluconazole concentrations of 2-250 µg/mL were tested. Moreover, biofilm production ability of tested isolates was tested on the polystyrene surface at 28 and 37 ± 0.5 °C and measured after crystal violet staining. Strains with the highest biofilm production ability were chosen for further analysis. Confocal microscopy photographs were taken after live/dead staining of fungal suspensions incubated with tested hydrogels (with and without fluconazole). Performed analyses confirmed that polymeric hydrogels are excellent drug carriers and, when fluconazole-loaded, they may be applied as the prevention of chronic wounds fungal infection.

An in vitro assessment of bacterial transfer by products used in debridement

OBJECTIVE

The aim of this in vitro study was to investigate the transfer of viable Pseudomonas aeruginosa biofilm microorganisms following treatment with debridement tools.

METHOD

The level of viable biofilm microorganisms transferred by debridement tools was compared following treatment that reflected the clinical practice of each product.

RESULTS

A significant level of microorganism transfer was seen in response to the mechanical debridement tool. Minimal transfer of microorganisms was seen when in vitro-established biofilms were treated with hydroresponsive wound dressing + polyhexamethylene biguanide (HRWD+PHMB, HydroClean plus). Less Pseudomonas aeruginosa was recovered from explants exposed to dressings compared with those exposed to debridement tools suggesting that there was less transfer of bacteria by dressings.

CONCLUSION

The reduced transfer of viable microorganisms by HRWD+PHMB may be the result of significant binding and retention of microbes by the superabsorbent polymer within the dressing, together with enhanced sequestered bacterial killing within the dressing by polymer-bound PHMB. The high levels of microbial transfer/transmission seen for debridement tools suggests that, in the clinical setting, a significant level of bacterial spread over the wound surface and/or surrounding skin by these cleansing tools is likely.

Simplifying wound dressing selection for residential aged care

OBJECTIVE

To demonstrate the effectiveness of a simplified wound dressing regimen and develop a decision tree tool for wound management, for use by nurses in a residential aged care setting.

METHOD

A three-phase process was used. Firstly, practice was audited, including a cost analysis of existing wound treatment. Secondly, staff were educated on wounds, wound care products and a simplified wound management protocol. In the final phase, the new wound care products and protocol used for skin tears and other wounds (as assessed by a nurse practitioner) were evaluated and ongoing education provided as required.

RESULTS

A total of 93 residents from two residential aged care facilities participated in the study. Overall, 178 wounds were identified, of which 121 were considered eligible for treatment under the new protocol. The majority of residents were aged >85 years and the major wound type was skin tears 72.7% (n=88). The mean healing time for skin tears was significantly shorter than for other wounds (19.7±14.2 days versus 30.9±25.2 days, p=0.0359). Most wounds were suitable for the simplified dressing selection regimen. Data collected from a survey of nursing staff demonstrated that the simplified protocol products were easy to apply, conformed well, were easy to remove and stayed in place. In addition, patient satisfaction was positive and removal of dressings was generally pain free.

CONCLUSION

In summary, data collected from this project showed that the dressings were effective, performed well and simplified wound dressing selection for nursing staff.

Hydro-responsive wound dressings simplify T.I.M.E. wound management framework

The development of wound management protocols and guidelines such as the T.I.M.E. acronym are useful tools to aid wound care practitioners deliver effective wound care. The tissue, infection/inflammation, moisture balance and edge of wound (T.I.M.E.) framework provides a systematic approach for the assessment and management of the majority of acute and chronic wounds. The debridement of devitalised tissue from the wound bed, the reduction in wound bioburden and effective management of wound exudate - i.e., wound bed preparation - are barriers to wound healing progression that are targeted by T.I.M.E. There are a large number of wound dressings available to experienced wound care practitioners to aid in their goal of healing wounds. Despite the systematic approach of T.I.M.E., the large number of wound dressings available can introduce a level of confusion when dressing choices need to be made. Any simplification in dressing choice, for example by choosing a dressing system comprising of a limited number of dressings that are able to address all aspects of T.I.M.E., would be a valuable resource for delivering effective wound care. This article briefly reviews the principles of T.I.M.E. and describes the evidence for the use of a two-dressing, moisture balance-oriented, dressing-based wound management system.

SAP-containing dressings exhibit sustained antimicrobial effects over 7 days in vitro

OBJECTIVE

To investigate the antimicrobial activity of SAP-containing wound dressings in vitro over a prolonged period of time (7 days) and to assess their ability to sustain the antimicrobial effect.

METHOD

SAP dressings were tested according to the JIS L 1902:2002 against the pathogens Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli and Candida albicans.Additionally, effect on S. aureus and P. aeruginosa growth was investigated after a prolonged incubation period of 7 days. Furthermore, both SAP dressings were repeatedly inoculated with P. aeruginosa suspension and, after 7 days, microbial growth under the dressings was evaluated.

RESULTS

Both SAP-containing wound dressings tested exhibited a significant to strong antimicrobial activity against Staphylococcus aureus, MRSA, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, and Candida albicans in vitro. Moreover, it could be shown that they were able to sustain antibacterial efficacy over a prolonged period of time. Using a direct incubation method with repeated re-inoculation of the dressing samples, it could be shown that growth of P. aeruginosa was reduced after 4 days of treatment and completely inhibited after 7 days. No significant differences were observed between the two SAP-dressings tested.

CONCLUSION

These in vitro experiments impressively demonstrated the antimicrobial mechanism of SAP-containing wound dressings: rapid up-take of fluid, binding of microorganisms to the SAP-core, and retention of the bacteria inside the dressing. Moreover, it could be shown that they are able to exhibit their antimicrobial activity over a prolonged period of time unless the amount of fluid present exceeds their fluid-handling capacity.

Superabsorbent polymer-containing wound dressings have a beneficial effect on wound healing by reducing PMN elastase concentration and inhibiting microbial growth

A comprehensive in vitro approach was used to assess the effects of superabsorbent polymer (SAP) containing wound dressings in treatment of non-healing wounds. A slight negative effect on HaCaT cells was noted in vitro which is most likely due to the Ca(2+) deprivation of the medium by binding to the SAP. It could be shown that SAP wound dressings are able to bind considerable amounts of elastase reducing enzyme activity significantly. Furthermore, SAP's inhibit the formation of free radicals. The SAP-containing wound dressings tested also exhibited a significant to strong antimicrobial activity effectively impeding the growth of gram-negative and gram-positive bacteria as well as yeasts. In conclusion, in vitro data confirm the positive effect of SAP wound dressings observed in vivo and suggest that they should be specifically useful for wound cleansing.

The local treatment and available dressings designed for chronic wounds

The great diversity of wounds and the broad range of available dressings complicate the selection of proper chronic wound treatment. Choosing the right treatment is the essential step in the healing process. In this review, we focus on chronic nonhealing ulcers, which are a critical problem in clinical practice, and current knowledge about persistent wound care. Here, we present the objectives of local treatment with description of several types of dressings and their ingredients, features, indications, and contraindications. These include hydrocolloid, alginate, hydrogel, and dextranomer dressings; polyurethane foam and membrane dressings; semipermeable polyurethane membrane dressings; and TenderWet (Hartmann, Rock Hill, SC) and flax dressings. There is also a brief section on the use of other alternative wound-healing accelerators, such as platelet-rich plasma and light-emitting diode therapy.