Multi-functional conductive hydrogels based on heparin-polydopamine complex reduced graphene oxide for epidermal sensing and chronic wound healing

Flexible hydrogel sensors have expanded the applications of electronic devices due to their suitable mechanical properties and excellent biocompatibility. However, conventionally synthesized reduced graphene oxide (rGO) encounters limitations in reduction degree and dispersion, restricting the conductivity of graphene hydrogels and impeding the development of high-sensitivity flexible sensors. Moreover, hydrogels are susceptible to inflammation and bacterial infections, jeopardizing sensor stability over time. Thus, the challenge persists in designing conductive hydrogels that encompass high sensitivity, antibacterial efficacy, and anti-oxidative capabilities. In this study, GO was modified and reduced via a heparin-polydopamine (Hep-PDA) complex, yielding well-reduced and uniformly dispersed Hep-PDA-rGO nanosheets. Consequently, a hydrogel utilizing Hep-PDA-rGO was synthesized, showcasing commendable conductivity (3.63 S/m) and sensor performance, effectively applied in real-time motion monitoring. Notably, the hydrogel's attributes extend to facilitating chronic diabetic wound healing. It maintained a suitable inflammatory environment credited to its potent antibacterial and antioxidative properties, while its inherent conductivity promoted angiogenesis. The multifunctional nature of this hydrogel highlight its potential not only as an epidermal sensor but also as a promising dressing candidate for chronic wound treatment.

The effect of wound electrical stimulation in venous leg ulcer healing-a systematic review

OBJECTIVE

The benefit of using electric stimulation therapy (EST) to heal venous leg ulcers (VLUs) is not well established. The main aim of this systematic review was to evaluate the effects of ulcer EST in VLU healing.

METHODS

A systematic search of the literature was conducted using the databases PubMed, Scopus, and Web of Science and included original studies that reported VLU healing after EST. The inclusion criteria were at least two surface electrodes placed on or near the wound or a planar probe covering the ulcer area to be treated. The Cochrane risk of bias tool for randomized control trials (RCTs) and Joanna Briggs Institute critical appraisal checklist for case series were used to evaluate the risk of bias.

RESULTS

This review included eight RCTs and three case series involving a total of 724 limbs in 716 patients with VLUs. The mean patient age was 64.2 years (95% confidence interval, 62.3-66.2), and 46.2% (95% confidence interval, 41.2%-50.4%) were men. The active electrode was placed on the wound with the passive electrode placed on healthy skin (n = 6), the two electrodes were placed on either side of the wound edges (n = 4), or a planar probe was used (n = 1). The pulsed current was the most used waveform (n = 9). The change in the ulcer size was the main method used to determine ulcer healing (n = 8), followed by the ulcer healing rate (n = 6), exudate levels (n = 4), and the time to healing (n = 3). Five RCTs detected a statistically significant improvement in at least one VLU healing outcome, after EST compared with the control group. In two of these, EST was better than the control but only for patients who had not undergone surgical treatment of VLU.

CONCLUSIONS

The findings from the present systematic review support the use of EST to accelerate wound healing of VLUs, especially for patients who are not surgical candidates. However, the significant variation in electric stimulation protocols represents an important limitation to its use and should be addressed in future studies.

Activation of healing and reduction of pain by single-use automated microcurrent electrical stimulation therapy in patients with hard-to-heal wounds

Evidence shows that Electrical Stimulation Therapy (EST) accelerates healing and reduces pain, but EST has yet to become widely used. One reason is the historical use of complex, clinic-based EST devices. This evaluation assessed the early response of different hard-to-heal wounds to a simple, wearable, single-use, automated microcurrent EST device (Accel-Heal, Accel-Heal Technologies Limited - Hever, UK). Forty wounds (39 patients: 18 female - 21 male), mean age 68.9 ± 14.0 years comprised of: seven post-surgical, three trauma, 12 diabetic foot (DFU), 10 venous (VLU), four pressure injuries (PI), four mixed venous or arterial ulcers (VLU/arterial) received automated microcurrent EST for 12 days. Early clinical responses were scored on a 0-5 scale (5-excellent-0-no response). Pain was assessed at 48 h, seven days, and 14 days on a 0-10 visual analogue scale (VAS). Overall, 78% of wounds showed a marked positive clinical response (scores of 5 and 4). Sixty eight percent of wounds were painful with a mean VAS score of 5.5. Almost every patient (96%) with pain experienced reduction within 48 h. All patients with painful wounds experienced pain reduction after seven days: 2.50 VAS (45% reduction) and further pain reduction after 14 days: 1.83 VAS (33%).

Electrochemical Devices in Cutaneous Wound Healing

In healthy skin, vectorial ion transport gives rise to a transepithelial potential which directly impacts many physiological aspects of skin function. A wound is a physical defect that breaches the epithelial barrier and changes the electrochemical environment of skin. Electroceutical dressings are devices that manipulate the electrochemical environment, host as well as microbial, of a wound. In this review, electroceuticals are organized into three mechanistic classes: ionic, wireless, and battery powered. All three classes of electroceutical dressing show encouraging effects on infection management and wound healing with evidence of favorable impact on keratinocyte migration and disruption of wound biofilm infection. This foundation sets the stage for further mechanistic as well as interventional studies. Successful conduct of such studies will determine the best dosage, timing, and class of stimulus necessary to maximize therapeutic efficacy.

Accelerated Skin Wound Healing by Electrical Stimulation

When the integrity of the skin got damaged, an endogenous electric field will be generated in the wound and a series of physiological reactions will be initiated to close the wound. The existence of the endogenous electric field of the wound has a promoting effect on all stages of wound healing. For wounds that cannot heal on their own, the exogenous electric field can assist the treatment. In this review, the effects of exogenous electrical stimulation on wound healing, such as the inflammation phase, blood flow, cell proliferation and migration, and the wound scarring is overviewed. This article also reviews the new electrical stimulation methods that have emerged in recent years, such as small power supplies, nanogenerators (NGs), and other physical, chemical or biological strategies. These new electrical stimulation methods and devices are safe, low-cost, stable, and small in size. The challenge and perspective are discussed for the future trends of the electrical stimulation treatment in accelerating skin wound healing.

Skin-inspired gelatin-based flexible bio-electronic hydrogel for wound healing promotion and motion sensing

Next generation tissue-engineered skin scaffolds promise to provide sensory restoration through electrical stimulation in addition to effectively rebuilding and repairing skin. The integration of real-time monitoring of the injury motion activities can fundamentally improve the therapeutic efficacy by providing detailed data to guide the clinical practice. Herein, a mechanically-flexible, electroactive, and self-healable hydrogels (MESGel) was engineered for the combinational function of electrically-stimulated accelerated wound healing and motion sensing. MESGel shows outstanding biocompatibility and multifunctional therapeutic properties including flexibility, self-healing characteristics, biodegradability, and bioelectroactivity. Moreover, MESGel shows its potential of being a novel flexible electronic skin sensor to record the injury motion activities. Comprehensive in vitro and in vivo experiments prove that MESGel can facilitate effective electrical stimulation, actively promoting proliferation in Chinese hamster lung epithelial cells and therefore can accelerate favorable epithelial biology during skin wound healing, demonstrating an effective therapeutic strategy for a full-thickness skin defect model and leading to new-type flexible bioelectronics.

The impact of continuous electrical microcurrent on acute and hard-to-heal wounds: a systematic review

BACKGROUND

Wound infections result in considerable morbidity, mortality and healthcare costs. Antibiotic resistance has complicated wound healing, and new, non-antibiotic-based treatment methods are being developed.

AIMS

To evaluate evidence on the safety, efficacy and real-world effectiveness of electroceutical devices (ECDs) that provide continuous electrical stimulation to wounds.

METHOD

A systematic search was conducted to identify primary studies published between 2009 and 2019 that described therapeutic wound treatment using portable ECDs. Studies were included if the ECD delivered continuous electrical current directly to the wound area for the duration of treatment.

RESULTS

Of 171 citations identified in the search, 13 articles met the inclusion criteria and were analysed. Nine studies evaluated dressings embedded with zinc and silver particles that generated electricity electrochemically, and four evaluated electrode-based units with external batteries. ECDs were effective in healing complex, hard-to-heal wounds that had not responded to other treatments. Four studies showed that ECDs led to complete closure of wounds without complications, and in some cases healed wounds faster than standard of care (SOC). One study found that ECDs resulted in higher ratings by both patients and surgeons than SOC for the progression of wound healing and scar appearance. Additionally, three studies found ECD treatment was less expensive than SOC, due to patients requiring fewer dressing changes or nurse visits.

CONCLUSION

ECDs appeared to be a safe, effective and cost-effective method for treating severe, complex and challenging wounds, including hard-to-heal wounds, surgical incisions and skin graft donor sites.

Possible implications and clinical value of commercially sponsored evaluations: discussion on research methodology

This paper is written in response to a publication in the Journal of Wound Care in 2018 by Guest et al., 'Cost-effectiveness of an electroceutical device in treating non-healing venous leg ulcers: results of an RCT'. The publication and subsequent analysis of the paper provides a vehicle for a wider debate about the care of people with wounds, including who manages the wound, how resources are allocated and the use of supplemental technologies. It also raises a further important issue regarding whether the outcomes from a single randomised controlled trial (RCT) provides a more reliable level of evidence than the findings of previous investigations involving observational trials. This article analyses the results from the cited study, comparing clinical outcomes from previous published studies, and evaluates whether a conclusion may be reached as to the most appropriate and reliable method to assess the efficacy of such medical devices used in wound care. It discusses why the assessment of clinical evidence can be a problem when there is variance of outcomes in studies which use different research methodologies. The hierarchy of evidence lies at the heart of the appraisal process; and within health-care it is common that smaller commercial companies present small-scale observational trials as evidence for the efficacy of the product they are promoting. We question whether this level of data promoted as evidence for clinical efficacy should be dismissed. Guest et al. reported that, in the UK within wound care, clinical practice is inconsistent with significant regional variations; therefore, unless clinical practice guidelines are strictly enforced in a study, which then may be unrepresentative of clinical practice, does it mean that any results produced could not be transferred to the clinical environment? We discuss the conundrum.

Low-intensity ultrasound attenuates paw edema formation and decreases vascular permeability induced by carrageenan injection in rats

Background

Therapeutic potential of low-intensity ultrasound (LIUS) has become evident in various musculoskeletal diseases. We have previously shown that LIUS has an inhibitory effect on local edema in various diseases including the arthritis and brain injury. In this study, we examined whether LIUS can attenuate paw edema formation vis-à-vis vascular permeability and inflammation in rats induced by carrageenan. LIUS with a frequency of 1 MHz and the intensities of 50, 100, or 200 mW/cm² were exposed on rat paws for 10 min immediately after carrageenan injection.

Results

Carrageenan injection induced paw edema which was peaked at 6 h and gradually decreased nearly to the initial baseline value after 72 h. LIUS showed a significant reduction of paw edema formation at 2 and 6 h at all intensities tested. The highest reduction was observed at the intensity of 50 mW/cm². Histological analyses confirmed that LIUS clearly decreased the carrageenan-induced swelling of interstitial space under the paw skin and infiltration of polymorphonuclear leukocytes. Moreover, Evans Blue extravasation analyses exhibited a significant decreases of vascular permeability by LIUS. Finally, immunohistochemical staining showed that expression of pro-inflammatory proteins, namely, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) induced by carrageenan injection was reduced back to the normal level after LIUS stimulation.

Conclusions

These results provide a new supporting evidence for LIUS as a therapeutic alternative for the treatment of edema in inflammatory diseases such as cellulitis.

Electroacupuncture: applications in the treatment of chronic nonhealing wounds

Maximizing the effectiveness of any wound treatment requires that normal wound-healing dynamics are appreciated. In considering adjuvant wound therapies, the clinical evidence supporting a therapy must be fully understood. The biological changes associated with electroacupuncture can have a positive effect on wound healing, although limited clinical data are available.

Electrical Stimulation and Cutaneous Wound Healing: A Review of Clinical Evidence

Electrical stimulation (ES) has been shown to have beneficial effects in wound healing. It is important to assess the effects of ES on cutaneous wound healing in order to ensure optimization for clinical practice. Several different applications as well as modalities of ES have been described, including direct current (DC), alternating current (AC), high-voltage pulsed current (HVPC), low-intensity direct current (LIDC) and electrobiofeedback ES. However, no one method has been advocated as the most optimal for the treatment of cutaneous wound healing. Therefore, this review aims to examine the level of evidence (LOE) for the application of different types of ES to enhance cutaneous wound healing in the skin. An extensive search was conducted to identify relevant clinical studies utilising ES for cutaneous wound healing since 1980 using PubMed, Medline and EMBASE. A total of 48 studies were evaluated and assigned LOE. All types of ES demonstrated positive effects on cutaneous wound healing in the majority of studies. However, the reported studies demonstrate contrasting differences in the parameters and types of ES application, leading to an inability to generate sufficient evidence to support any one standard therapeutic approach. Despite variations in the type of current, duration, and dosing of ES, the majority of studies showed a significant improvement in wound area reduction or accelerated wound healing compared to the standard of care or sham therapy as well as improved local perfusion. The limited number of LOE-1 trials for investigating the effects of ES in wound healing make critical evaluation and assessment somewhat difficult. Further, better-designed clinical trials are needed to improve our understanding of the optimal dosing, timing and type of ES to be used.

Electrical stimulation vs. standard care for chronic ulcer healing: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

We conducted a systematic review to investigate the effect of electrical stimulation on ulcer healing compared to usual treatment and/or sham stimulation. This systematic review also aimed to investigate the effect of different types of electrical stimulation on ulcer size reduction.

MATERIALS AND METHODS

MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials (CENTRAL) were searched from inception to October 2013 on randomised controlled trials (RCTs), in English and on human subjects, which assessed the effect of electrical stimulation on ulcer size as compared to standard care and/or sham stimulation. Data from included RCTs were pooled with use of fixed and random effects meta-analysis of the weighted mean change differences between the comparator groups. Heterogeneity across studies was assessed with the I(2) statistic.

RESULTS

Twenty-one studies were eligible for inclusion in the meta-analysis. In six trials (n = 210), electrical stimulation improved mean percentage change in ulcer size over total studies periods by 24·62%, 95% confidence interval (CI) 19·98-29·27, P < 0·00001 with no heterogeneity. In three trials (n = 176), electrical stimulation insignificantly improved mean weekly change in ulcer size by 1·64%, 95% (CI) -3·81 to 7·09, P = 0·56 with significant heterogeneity (I(2) = 96%, P < 0·00001). In six trials (n = 266), electrical stimulation decreased ulcer size by 2·42 cm(2), 95% (CI) 1·66-3·17, P < 0·00001, with significant heterogeneity. In one trial (n = 16), electrical stimulation also insignificantly improved the mean daily percentage change in ulcer size by 0·63%, 95% (CI) -0·12 to 1·37, P = 0·10, with significant heterogeneity.

CONCLUSIONS

Electrical stimulation appears to increase the rate of ulcer healing and may be superior to standard care for ulcer treatment.

Modelling the cost-effectiveness of electric stimulation therapy in non-healing venous leg ulcers

OBJECTIVE

To estimate the cost-effectiveness of using electric stimulation (ES) therapy (Accel-Heal) plus dressings and compression bandaging compared with dressings and compression bandaging alone in treating chronic, non-healing venous leg ulcers (VLUs) of >6 months' duration from the perspective of the National Health Service (NHS) in the UK.

METHOD

A 5-month Markov model was constructed, depicting the management of a chronic, non-healing VLU of >6 months' duration. The model considers the decision by a clinician to continue with a patient's previous care plan (comprising dressings and compression bandaging) or treating with ES therapy plus dressings and compression bandaging. The model was used to estimate the relative cost-effectiveness of ES therapy at 2008-2009 prices.

RESULTS

According to the model, 38% of VLUs are expected to heal within 5 months after starting ES therapy, with a further 57% expected to improve. This improvement in clinical outcome is expected to lead to a 6% health gain of 0.017 QALYs (from 0.299 to 0.316 QALYs) over 5 months. The model also showed that using ES therapy instead of continuing with a patient's previous care plan is expected to reduce the NHS cost of managing them by 15%, from £880 to £749, due in part to a 27% reduction in the requirement for nurse visits (from mean 49.0 to 35.9 visits per patient) over the first 5 months after the start of treatment. Hence, use of ES therapy was found to be a dominant treatment (improved outcome for less cost).

CONCLUSION

Within the model's limitations, use of ES therapy potentially affords the NHS a cost-effective treatment, compared with patients remaining on their previous care plan in managing chronic, non-healing VLUs of >6 months' duration. However, this is dependant on the number of ES therapy units per treatment, the unit cost of the device, and the number of nurse visits required to manage patients in clinical practice.

DECLARATION OF INTEREST

This study was sponsored by Synapse Microcurrent Ltd., manufacturers of Accel-Heal. The authors have no other conflicts of interest that are directly relevant to the content of this manuscript. In particular, Synapse Microcurrent Ltd. had no role in the study design, in the collection, analysis and interpretation of data, or in writing the manuscript.