Mode of action of poloxamer-based surfactants in wound care and efficacy on biofilms

Cellulose- and Saccharide-Based Orally Dispersible Thin Films Transform the Solid States and Dissolution Characteristics of Poorly Soluble Curcumin

This study aimed at developing and optimizing the orally dispersible thin film (ODTF) containing a plant-derived drug-curcumin (CUR). CUR belongs to a biopharmaceutical classification system (BCS) class IV compound that requires improving its water solubility and tissue permeability preceding formulation. An ODTF was applied to produce a solid dispersion matrix for CUR to resolve such solubility and permeability problems. The film-forming polymers used in the study were cellulose-based (hydroxypropyl methylcellulose/HPMC and carboxymethylcellulose/CMC) and saccharide-based maltodextrin (MDX). Poloxamer (POL) was also employed as surfactant and solubilizer. The solvent casting technique was applied to produce the films. The ethanolic solution of CUR was mixed with an aqueous solution of POLs and then incorporated into different film-forming polymers prior to casting. The processing of the CUR with POL solution was intended to aid in the even dispersion of the drug in the polymeric matrices and enhance the wettability of the films. The physical state and properties of the films were characterized in terms of their morphology, crystallinity of the drug, and phase miscibility of the mixtures. The dissolution profile of the films was also evaluated in terms of dissolution rate and dissolution efficiency. The obtained ODTF products were smooth and flat-surfaced. Physical characterization also indicated that the CUR was homogeneously dispersed in the ODTFs and no longer existed as crystalline material as revealed by X-ray diffraction (XRD). The CUR was also not phase-separated from the films as disclosed by differential scanning calorimetry (DSC). Such dispersion was achieved through the solubilizing effect of POLs and compact polymeric film matrices that prevented the CUR from recrystallization. Furthermore, the ODTFs also improved the dissolution of CUR by 3.2-fold higher than the raw CUR. Overall, cellulose-based films had favorable physical properties compared with saccharide-based films.

A surfactant-based dressing can reduce the appearance of Pseudomonas aeruginosa pigments and uncover the dermal extracellular matrix in an ex vivo porcine skin wound model

From previous studies, we have shown that viable colony forming units of bacteria and bacterial biofilms are reduced after sequential treatment with a surfactant-based dressing. Here, we sought to test the impact on visible bacterial pigments and the ultrastructural impact following the sequential treatment of the same surfactant-based dressing. Mature Pseudomonas aeruginosa biofilms were grown on ex vivo porcine skin explants, and an imaging-based analysis was used to compare the skin with and without a concentrated surfactant. In explants naturally tinted by bacterial chromophores, wiping alone had no effect, while the use of a surfactant-based dressing reduced coloration. Similarly, daily wiping led to increased immunohistochemical staining for P. aeruginosa antigens, but not in the surfactant group. Confocal immunofluorescent imaging revealed limited bacterial penetration and coating of the dermis and loose pieces of sloughing material. Ultrastructural analysis confirmed that the biofilms were masking the extracellular matrix (ECM), but the surfactant could remove them, re-exposing the ECM. The masking of the ECM may provide another non-inflammatory explanation for delayed healing, as the ECM is no longer accessible for wound cell locomotion. The use of a poloxamer-based surfactant appears to be an effective way to remove bacterial chromophores and the biofilm coating the ECM fibres.

Biofouling on titanium implants: a novel formulation of poloxamer and peroxide for in situ removal of pellicle and multi-species oral biofilm

Eradicating biofouling from implant surfaces is essential in treating peri-implant infections, as it directly addresses the microbial source for infection and inflammation around dental implants. This controlled laboratory study examines the effectiveness of the four commercially available debridement solutions '(EDTA (Prefgel®), NaOCl (Perisolv®), H2O2 (Sigma-Aldrich) and Chlorhexidine (GUM® Paroex®))' in removing the acquired pellicle, preventing pellicle re-formation and removing of a multi-species oral biofilm growing on a titanium implant surface, and compare the results with the effect of a novel formulation of a peroxide-activated 'Poloxamer gel (Nubone® Clean)'. Evaluation of pellicle removal and re-formation was conducted using scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy to assess the surface morphology, elemental composition and chemical surface composition. Hydrophilicity was assessed through contact angle measurements. The multi-species biofilm model included Streptococcus oralis, Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans, reflecting the natural oral microbiome's complexity. Biofilm biomass was quantified using safranin staining, biofilm viability was evaluated using confocal laser scanning microscopy, and SEM was used for morphological analyses of the biofilm. Results indicated that while no single agent completely eradicated the biofilm, the 'Poloxamer gel' activated with 'H2O2' exhibited promising results. It minimized re-contamination of the pellicle by significantly lowering the contact angle, indicating enhanced hydrophilicity. This combination also showed a notable reduction in carbon contaminants, suggesting the effective removal of organic residues from the titanium surface, in addition to effectively reducing viable bacterial counts. In conclusion, the 'Poloxamer gel + H2O2' combination emerged as a promising chemical decontamination strategy for peri-implant diseases. It underlines the importance of tailoring treatment methods to the unique microbial challenges in peri-implant diseases and the necessity of combining chemical decontaminating strategies with established mechanical cleaning procedures for optimal management of peri-implant diseases.

An objective comparative study of non-surgical cleansing techniques and cleanser types in bacterial burden management

Cleansing is a vital component of effective wound hygiene and biofilm management, often accomplished through vigorous mechanical action or through soaking with moistened gauze. In the present study, a quantitative comparison of the effectiveness of different cleansing techniques and solutions in removing bacteria was conducted on 71 chronic wounds using bacterial fluorescence imaging as a real-time diagnostic for moderate to high bacterial loads. Vigorous gauze cleansing for 30 s proved most effective by reducing bacterial fluorescence by 33.99%, surpassing 10-min soaking in bacterial reduction (13.24%). Among different cleansers, no statistically significant differences in effectiveness were observed, but povidone-iodine showed the strongest trend towards bacterial reduction. Sub-analysis highlighted the superiority of antiseptic cleansers over saline and gentle soap (-33.30% vs. -1.80% bacterial reduction respectively). Five percent acetic acid was also shown to be more effective in removing specific bacterial strains (Pseudomonas aeruginosa). Findings from studies like this contribute to refining wound hygiene guidelines and clinical algorithms for bacterial and biofilm management.

What is the impact of intraperitoneal surfactant administration against postoperative intraabdominal adhesion formation? an experimental study

Background/Aim

Surfactant is a surface-active substance that, in addition to its detergent effect, also has effects that reduce inflammation and fibrosis. Because of these effects, it was aimed herein to investigate the effect of intraperitoneal surfactant application on preventing postoperative peritoneal adhesion formation in a uterine horn adhesion model.

Materials and methods

Twenty-one Wistar albino rats were randomly divided into 3 groups (G1-G3), as follows: G1 (n = 7): control group. The abdomen was opened and then closed; G2 (n = 7): adhesion group. The abdomen was opened. Then, a 2-cm linear incision was made over the right uterine horn, 2 mL of isotonic saline was administered intraperitoneally, and the abdomen was closed; and G3 (n = 7): treatment group. The abdomen was opened, a 2-cm linear incision was made over the right uterine horn, 2 mL (70 mg/kg) of surfactant was administered intraperitoneally, and the abdomen was closed. After 15 days, the rats were euthanized, the abdomens were reopened, and adhesion scoring was performed. After the right uterine horns were removed and fixed with 10% formalin, appropriate sections were taken from the traumatized tissue, stained with Masson's trichrome, and fibrosis and inflammation scoring were performed.

Results

The adhesion area and intensity were significantly higher in G2 than in G1 and G3 (p = 0.001) and were similar in G1 and G3 (p = 0.165). While fibrosis and inflammation were significantly higher in G2 than in G1 and G3 (p = 0.001), there was no difference between G1 and G3 (p = 0.5).

Conclusion

Intraperitoneal surfactant administration at a dose of 70 mg/kg was found to be effective in preventing intraabdominal adhesion formation in a rat uterine horn model.

A Comparative Investigation of Chemical Decontamination Methods for In-Situ Cleaning of Dental Implant Surfaces

Surface chemistry evaluation is crucial in assessing the efficacy of chemical decontamination products for titanium implants. This study aimed to investigate the effectiveness of chemical decontamination solutions in cleaning a contaminated dental implant surface and to evaluate the potential of combining Pluronic gel with hydrogen peroxide (NuBone®Clean) by evaluating pellicle disruption and re-formation on implant surfaces. In addition, ensuring safety with in vitro and human testing protocols. X-ray Photoelectron Spectroscopy (XPS) was utilised for surface analysis. All the tested gels had some effect on the surface cleanness except for PrefGel®. Among the tested chemical decontamination candidates, NuBone®Clean demonstrated effectiveness in providing a cleaner titanium surface. Furthermore, none of the tested chemical agents exhibited cytotoxic effects, and the safety assessment showed no adverse events. The results of this study highlight the significance of conducting comprehensive evaluations, encompassing safety and efficacy, before introducing new chemical agents for dental treatments. The findings suggest that NuBone®Clean shows potential as a chemical decontamination solution for implant surfaces. However, further investigation through randomised clinical trials is necessary. By adhering to rigorous testing protocols, the development of safe and efficient chemical decontamination strategies can be advanced, benefiting patients and promoting progress in implant dentistry.

Effects of Poloxamers as Excipients on the Physicomechanical Properties, Cellular Biocompatibility, and In Vitro Drug Release of Electrospun Polycaprolactone (PCL) Fibers

Electrospun microfibers are emerging as one of the advanced wound dressing materials for acute and/or chronic wounds, especially with their ability to carry drugs and excipients at a high loading while being able to deliver them in a controlled manner. Various attempts were made to include excipients in electrospun microfibers as wound dressing materials, and one of them is poloxamer, an amphiphilic polymer that exhibits wound debridement characteristics. In this study, we formulated two types of poloxamers (i.e., P188 and P338) at 30% (w/w) loading into electrospun polycaprolactone (PCL) fibers to evaluate their physicomechanical properties, biocompatibility, and in vitro drug release of a model drug. Our findings showed that the incorporation of poloxamers in the PCL solutions during electrospinning resulted in a greater "whipping" process for a larger fiber deposition area. These fibers were mechanically stiffer and stronger, but less ductile as compared to the PCL control fibers. The incorporation of poloxamers into electrospun PCL fibers reduced the surface hydrophobicity of fibers according to our water contact angle studies and in vitro degradation studies. The fibers' mechanical properties returned to those of the PCL control groups after "dumping" the poloxamers. Moreover, poloxamer-loaded PCL fibers accelerated the in vitro release of the model drug due to surface wettability. These poloxamer-loaded PCL fibers were biocompatible, as validated by MTT assays using A549 cells. Overall, we demonstrated the ability to achieve a high loading of poloxamers in electrospun fibers for wound dressing applications. This work provided the basic scientific understanding of materials science and bioengineering with an emphasis on the engineering applications of advanced wound dressings.

What’s old is new again: Insights into diabetic foot microbiome

Diabetes is a chronic disease that is considered one of the most stubborn global health problems that continues to defy the efforts of scientists and physicians. The prevalence of diabetes in the global population continues to grow to alarming levels year after year, causing an increase in the incidence of diabetes complications and health care costs all over the world. One major complication of diabetes is the high susceptibility to infections especially in the lower limbs due to the immunocompromised state of diabetic patients, which is considered a definitive factor in all cases. Diabetic foot infections continue to be one of the most common infections in diabetic patients that are associated with a high risk of serious complications such as bone infection, limb amputations, and life-threatening systemic infections. In this review, we discussed the circumstances associated with the high risk of infection in diabetic patients as well as some of the most commonly isolated pathogens from diabetic foot infections and the related virulence behavior. In addition, we shed light on the different treatment strategies that aim at eradicating the infection.

A new protective gel to facilitate ulcer healing in artificial ulcers following oesophageal endoscopic submucosal dissection: a multicentre, randomized trial

There are significant risks of adverse events following oesophageal endoscopic submucosal dissection (ESD), such as stricture, delayed bleeding and perforation. Therefore, it is necessary to protect artificial ulcers and promote the healing process. The current study was performed to investigate the protective role of a novel gel against oesophageal ESD-associated wounds. This was a multicentre, randomized, single-blind, controlled trial that recruited participants who underwent oesophageal ESD in four hospitals in China. Participants were randomly assigned to the control or experimental group in a 1:1 ratio and the gel was used after ESD in the latter. Masking of the study group allocations was only attempted for participants. The participants were instructed to report any adverse events on post-ESD days 1, 14, and 30. Moreover, repeat endoscopy was performed at the 2-week follow-up to confirm wound healing. Among the 92 recruited patients, 81 completed the study. In the experimental group, the healing rates were significantly higher than those in the control group (83.89 ± 9.51% vs. 73.28 ± 17.81%, P = 0.0013). Participants reported no severe adverse events during the follow-up period. In conclusion, this novel gel could safely, effectively, and conveniently accelerate wound healing following oesophageal ESD. Therefore, we recommend applying this gel in daily clinical practice.

Formulation optimization of sterilized xanthones-loaded nanoemulgels and evaluation of their wound healing activities

Xanthones (XTs) are bioactive compounds found in mangosteen trees (Garcinia mangostana Linn.). They are used as an active ingredient in various health products. However, there is a lack of data of their application in wound healing. In particular, the topical products of XTs for wound healing; they should be sterilized to minimize the risks of wound infection from contaminated microorganisms. This study thus aimed to optimize the formulation of sterilized XTs-loaded nanoemulgel (XTs-NE-G) and to investigate their wound healing activities. The XTs-NE-Gs were prepared by mixing various gels containing sodium alginate (Alg) and Pluronic F127 (F127) into a XTs-nanoemulsion (NE) concentrate according to the face-centered central composite design. The results showed that the optimized XTs-NE-G was A5-F3 containing 5% w/w Alg and 3% w/w F127. It enhanced the proliferation-, migration rates of skin fibroblasts (HFF-1 cells) with an optimal viscosity. After blending the XTs-NE concentrate and the gel that was previously sterilized by a membrane filtration and an autoclaving technique, respectively, the sterilized A5-F3 was obtained. The sterilized A5-F3 still had effective bioactivities towards the HFF-1 cells. It promoted re-epithelialization, collagen deposition and inflammation suppression in the mice' wounds. It could thus be accepted for further investigation in clinical studies.

The Multifunctional Role of Poloxamer P338 as a Biofilm Disrupter and Antibiotic Enhancer: A Small Step forward against the Big Trouble of Catheter-Associated Escherichia coli Urinary Tract Infections

Poloxamer 338 (P338), a nonionic surfactant amphiphilic copolymer, is herein proposed as an anti-biofilm compound for the management of catheter-associated urinary tract infections (CAUTIs). P338’s ability to disrupt Escherichia coli biofilms on silicone urinary catheters and to serve as antibiotic enhancer was evaluated for biofilm-producing E. coli Ec5FSL and Ec9FSL clinical strains, isolated from urinary catheters. In static conditions, quantitative biofilm formation assay allowed us to determine the active P338 concentration. In dynamic conditions, the BioFlux system, combined with confocal laser scanning microscopy, allowed us to investigate the P338 solution’s ability to detach biofilm, alone or in combination with sub-MIC concentrations of cefoxitin (FOX). The 0.5% P338 solution was able to destroy the structure of E. coli biofilms, to reduce the volume and area fraction covered by adherent cells (41.42 ± 4.79% and 56.20 ± 9.22% reduction for the Ec5FSL and Ec9FSL biofilms, respectively), and to potentiate the activity of 1\2 MIC FOX in disaggregating biofilms (19.41 ± 7.41% and 34.66 ± 3.75% reduction in the area fraction covered by biofilm for Ec5FSL and Ec9FSL, respectively) and killing cells (36.85 ± 7.13% and 32.33 ± 4.65% increase in the biofilm area covered by dead Ec5FSL and Ec9FSL cells, respectively).

Embedding Wound Hygiene into a proactive wound healing strategy

Foreword. Wound Hygiene: the next stage

Since a panel published the first consensus document on Wound Hygiene in March 2020, there has been a flurry of activity in support of this newly established concept in proactive wound healing. 1 The document concluded that all wounds, particularly hard-to-heal ones, will benefit from Wound Hygiene, which should be initiated at the first referral, following a full holistic assessment to identify the wound aetiology and comorbidities, and then implemented at every dressing change until full healing occurs. 1 The consensus has since been bolstered by educational webinars; competency-based skills training and support; development of international Wound Hygiene ambassadors; a survey of 1478 respondents, published in July 2021; 2 and a case study supplement, published in January 2022, featuring a range of wound types, anatomies and underlying conditions on the improvements in wound-healing progress that can be achieved. 3 Wound Hygiene has gained its own identity and is now a term in and of itself, that encompasses a 4-step protocol of care. It is an antibiofilm approach that is increasingly being used across wound care. The results of the survey 2 were particularly encouraging for seeing how far Wound Hygiene has come, and how quickly: More than half (57.4%) had heard of the concept of Wound Hygiene Of those, 75.3% have implemented Wound Hygiene Overall, following implementation of Wound Hygiene, 80.3% of respondents reported improved healing rates. 2 However, the top three barriers identified by the survey—lack of confidence, competence and research data—show that there is more to be done to support Wound Hygiene in practice. 2 As a result, a consensus panel of international key opinion leaders convened virtually in the summer of 2021 to discuss what has been done so far, the outputs of the survey, and ideas for addressing the unmet needs identified by the results. The result is this publication, which represents an addendum to the initial consensus document, broadening support for implementation of Wound Hygiene. This document will reflect on the reasons Wound Hygiene has been successful in its first two years of implementation, reiterating its DNA: Do not wait to treat hard-to-heal wounds Use a simple 4-step approach Enable all healthcare professionals to implement and use Wound Hygiene. The document will also discuss the evolution of the Wound Hygiene concept, focusing on how and when to implement Wound Hygiene on all tissue types of hard-to-heal wounds, and proposing what these are. The panel has expanded the framework in which Wound Hygiene is used, with the ultimate objective of introducing the concept of ‘embedding Wound Hygiene intro a proactive wound healing strategy.’ Key inefficiencies are often observed along the journeys of people living with hard-to-heal wounds. The limited number of specialised healthcare professionals and the resulting delays in reaching them may increase the likelihood of a hard-to-heal wound developing. In a world where so much is happening so quickly that we may, at times, feel powerless to drive change, the panel wants to provide further guidance to propel the use of Wound Hygiene. The concept of Wound Hygiene is resonating, and the panel wants you to know that in whatever region you work, in whatever area of clinical practice, you are enabled to make this change. Wielding the 4-step Wound Hygiene protocol consistently is a key action every healthcare professional in every care setting can take to tackle the global wound care crisis. Wound Hygiene has taken off—now, where do we want to land? In a place where Wound Hygiene is practised on all wounds, at every stage, until healing. The panel once again recognises that the community of global healthcare providers should consider their local standards and guidelines when applying the recommendations of this document. To this end, the panel has created a flexible 3-phase framework that situates Wound Hygiene as integral to proactive wound healing. The panel hopes you will continue to implement Wound Hygiene and see the benefits it can bring to people living with wounds, as well as those who care for them.

The Investigation of Thymol Formulations Containing Poloxamer 407 and Hydroxypropyl Methylcellulose to Inhibit Candida Biofilm Formation and Demonstrate Improved Bio-Compatibility

The aim of this study was to investigate the potential of thymol to inhibit Candida biofilm formation and improve thymol biocompatibility in the presence of hydroxypropyl methylcellulose (HPMC) and poloxamer 407 (P407), as possible drug carriers. Thymol with and without polymers were tested for its ability to inhibit biofilm formation, its effect on the viability of biofilm and biocompatibility studies were performed on HEK 293 (human embryonic kidney) cells. Thymol showed a concentration dependent biofilm inhibition; this effect was slightly improved when it was combined with HPMC. The Thymol-P407 combination completely inhibited the formation of biofilm and the antibiofilm effect of thymol decreased as the maturation of Candida biofilms increased. The effect of thymol on HEK 293 cells was a loss of nearly 100% in their viability at a concentration of 250 mg/L. However, in the presence of P407, the viability was 25% and 85% using neutral red uptake and sulforhodamine B assays, respectively. While, HPMC had less effect on thymol activity the thymol-P407 combination showed a superior inhibitory effect on biofilm formation and better biocompatibility with human cell lines. The combination demonstrates a potential medical use for the prevention of Candida biofilm formation.

Curcuma longa L. Effects on Akt/mTOR Pathway and NF-κB Expression During Skin Wound Healing: An Immunohistochemical Study

Skin ulcers, wounds, or burns represent a burden for health care worldwide. Our aim was to explore the effects of mucoadhesive formulation with Curcuma longa L. extract mucoadhesive formulation containing curcumin (MFC) on skin healing in Wistar rats. Fifty-four rats were randomly allocated into 3 groups: control, vehicle, and MFC. A full-thickness circular wound was induced on the back of each animal. Two daily applications of the products were performed according to the experimental group. On days 3, 10, and 21, 6 animals in each group were euthanized. Clinical analysis was based on wound area. Histologic analysis was performed in hematoxylin and eosin-stained sections, with re-epithelization and inflammation being assessed by means of semiquantitative scores. To analyze the Akt/mTOR pathway, immunohistochemistry for phospho Akt (pAkt) and phospho ribosomal protein S6 were investigated. In addition, nuclear factor kappa-light-chain-enhancer of activated B cells immunolabeling was performed. Clinical analysis revealed wounds with a smaller area on days 3 and 10 in curcumin-treated animals. Histologically, MFC had a significant impact on inflammatory events on days 3 and 10 and promoted faster re-epithelization, which was evidenced on day 10. MFC-treated wounds exhibited pAkt upregulation on day 10 and both pAkt and phospho ribosomal protein S6 downregulation on day 21. Nuclear factor kappa-light-chain-enhancer of activated B cells expression varied through the evaluation periods; however, no significant difference was observed between groups. Collectively, our results indicate that MFC is efficient in accelerating cutaneous wound repair through modulation of the inflammatory process and stimulus of re-epithelization by an Akt/mTOR-dependent mechanism.

Alternative Approaches for the Management of Diabetic Foot Ulcers

Diabetic foot ulcers (DFU) represent a growing public health problem. The emergence of multidrug-resistant (MDR) bacteria is a complication due to the difficulties in distinguishing between infection and colonization in DFU. Another problem lies in biofilm formation on the skin surface of DFU. Biofilm is an important pathophysiology step in DFU and may contribute to healing delays. Both MDR bacteria and biofilm producing microorganism create hostile conditions to antibiotic action that lead to chronicity of the wound, followed by infection and, in the worst scenario, lower limb amputation. In this context, alternative approaches to antibiotics for the management of DFU would be very welcome. In this review, we discuss current knowledge on biofilm in DFU and we focus on some new alternative solutions for the management of these wounds, such as antibiofilm approaches that could prevent the establishment of microbial biofilms and wound chronicity. These innovative therapeutic strategies could replace or complement the classical strategy for the management of DFU to improve the healing process.

Factors Affecting the Penetration of Niosome into the Skin, Their Laboratory Measurements and Dependency to the Niosome Composition: A Review

Skin, the most significant protective organ in the body, may face serious problems, including cancer, infectious diseases, etc., requiring different drugs for the treatment. However, most of these drugs have poor chemical and physical stability, and insufficient penetration through the skin layers. In recent years, with the development of nanotechnology, it has been possible to load a variety of drugs into nanocarriers, to effectively targeted drug delivery. The unique structure of niosome presents an effective novel drug delivery system with the ability to load both hydrophilic and lipophilic drugs, having many potential therapeutic applications including skin treatment. However, surveying and discussing these recent, rapidly growing reported studies, along with their theoretical principals, are required for the full understanding and exploring the great potential of this approach in skin diseases and cosmetic treatments. To this aim, an emphasis has been given to the factors affecting the penetration of niosome into the skin and their laboratory measurements and dependency on the niosome composition. In sum, longer tail surfactants for storing hydrophobic drugs and intracellular passing and surfactants with a large head group for penetrating hydrophilic drugs are more suitable. Cholesterol and oleic acid are commonly used lipids to gain more stability and permeability, respectively. The ionic component in the niosome interrupts cellular connectivity, thus making it more permeable, but it may cause relative cell toxicity. Herbal oils have been used in the structure to make the nanoparticles elastic and allow them to pass through pores without changing the size of the particles.

Screening of Surfactants for Improved Delivery of Antimicrobials and Poly-Lactic-co-Glycolic Acid Particles in Wound Tissue

Topical wound management is often a challenge due to the poor penetration of antimicrobials in wound tissue and across the biofilm matrix where bacteria are embedded. Surfactants have been used for decades to improve the stability of formulations, increase drug solubility, and enhance penetration. In this study, we screened different detergents with respect to their cytotoxicity and their ability to improve the penetration of poly-lactic-co-glycolic acid (PLGA) particles in wound tissue. Among the tested surfactants, Kolliphor SLS and Tween 80 increased the penetration of PLGA particles and had a limited cytotoxicity. Then, these surfactants were used to formulate PLGA particles loaded with the poorly water-soluble antibiotic ciprofloxacin. The antimicrobial efficacy of the formulations was tested in a wound infection model based on human ex vivo skin. We found that even though PLGA particles had the same antimicrobial efficiency than the particle-free drug formulation, thanks to their solubilizing and anti-biofilm properties, the surfactants remarkably improved the antimicrobial activity of ciprofloxacin with respect to the drug formulation in water. We conclude that the use of Tween 80 in antimicrobial formulations might be a safe and efficient option to improve the topical antimicrobial management of chronic wound infections.

SARS-CoV-2 decontamination of skin with disinfectants active during and after application

Background

The coronavirus disease 2019 pandemic has resulted in high levels of exposure of medical workers to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Hand decontamination is one of the actions recommended to reduce the risk of infection.

Aim

Two disinfectants – BIAKŌS antimicrobial skin and wound cleanser (AWC) and AWC2 (Sanara MedTech, Fort Worth, TX, USA) – were tested to determine whether they can inactivate SARS-CoV-2 upon contact or as a coating applied before contact with the virus.

Methods

The ability of AWC and AWC2 to inactivate SARS-CoV-2 was tested in liquid and dried form on plastic surfaces and porcine skin.

Findings

AWC and AWC2 were effective in reducing the infectious titre of SARS-CoV-2 in liquid form during application and in dried form 4 h after application. Virus on skin was reduced up to 2 log₁₀-fold and 3.5 log₁₀-fold after treatment with AWC and AWC2, respectively.

Conclusion

Application of AWC and AWC2 to skin reduces the level of SARS-CoV-2 and the risk of infection.

Frequent template switching in postreplication gaps: suppression of deleterious consequences by the Escherichia coli Uup and RadD proteins

When replication forks encounter template DNA lesions, the lesion is simply skipped in some cases. The resulting lesion-containing gap must be converted to duplex DNA to permit repair. Some gap filling occurs via template switching, a process that generates recombination-like branched DNA intermediates. The Escherichia coli Uup and RadD proteins function in different pathways to process the branched intermediates. Uup is a UvrA-like ABC family ATPase. RadD is a RecQ-like SF2 family ATPase. Loss of both functions uncovers frequent and RecA-independent deletion events in a plasmid-based assay. Elevated levels of crossing over and repeat expansions accompany these deletion events, indicating that many, if not most, of these events are associated with template switching in postreplication gaps as opposed to simple replication slippage. The deletion data underpin simulations indicating that multiple postreplication gaps may be generated per replication cycle. Both Uup and RadD bind to branched DNAs in vitro. RadD protein suppresses crossovers and Uup prevents nucleoid mis-segregation. Loss of Uup and RadD function increases sensitivity to ciprofloxacin. We present Uup and RadD as genomic guardians. These proteins govern two pathways for resolution of branched DNA intermediates such that potentially deleterious genome rearrangements arising from frequent template switching are averted.

Photothermal-Induced Antibacterial Activity of Gold Nanorods Loaded into Polymeric Hydrogel against Pseudomonas aeruginosa Biofilm

In this study, the photothermal-induced bactericidal activity of phospholipid-decorated gold nanorods (DSPE-AuNR) suspension against Pseudomonas aeruginosa planktonic and biofilm cultures was investigated. We found that the treatment of planktonic culture of Pseudomonas aeruginosa with DSPE-AuNR suspension (0.25-0.03 nM) followed by a continuous laser beam exposure resulted in ~6 log cycle reduction of the bacterial viable count in comparison to the control. The percentage reduction of Pseudomonas aeruginosa biofilm viable count was ~2.5-6.0 log cycle upon laser excitation with different concentrations of DSPE-AuNR as compared to the control. The photothermal ablation activity of DSPE-AuNR (0.125 nM) loaded into poloxamer 407 hydrogel against Pseudomonas aeruginosa biofilm resulted in ~4.5-5 log cycle reduction in the biofilm viable count compared to the control. Moreover, transmission electron microscope (TEM) images of the photothermally-treated bacteria revealed a significant change in the bacterial shape and lysis of the bacterial cell membrane in comparison to the untreated bacteria. Furthermore, the results revealed that continuous and pulse laser beam modes effected a comparable photothermal-induced bactericidal activity. Therefore, it can be concluded that phospholipid-coated gold nanorods present a promising nanoplatform to eradicate Pseudomonas aeruginosa biofilm responsible for common skin diseases.

In vitro cellular viability studies on a concentrated surfactant-based wound dressing

In this study, three cellular cytotoxic assays (direct contact assay, extraction assay, and cell insert assay) were applied to evaluate the effects of a concentrated surfactant gel preserved with antimicrobials and a concentrated surfactant gel with 1% silver sulfadiazine on both the mouse fibroblast cell line L929 and human dermal fibroblasts (HDFa). Also, the in vitro wound model was wounded by a 100 μL pipette tip and used to assess cell migration and wound closure after treatment with both gels. A needle-scratched membrane disruption model was used to preliminarily evaluate membrane stabilisation and the membrane-resealing effects of concentrated surfactant gels. It was demonstrated that the concentrated surfactant gel preserved with antimicrobials was not toxic to both L929 and HDFa. However, the concentrated surfactant gel with 1% silver sulfadiazine demonstrated a degree of cytotoxicity to both cell types. After treatment with a concentrated surfactant gel preserved with antimicrobials, cell movement to close the scratch gap was enhanced at 24 and 48 hours. The results also showed that cells treated with the concentrated surfactant gel preserved with antimicrobials decreased cell necrosis and improved cell resistance of the f-actin rearrangement after a needle scratch. The results demonstrated that a concentrated surfactant gel preserved with antimicrobials is non-cytotoxic and has ability to accelerate wound closure by enhancing cell mobility. Furthermore, the concentrated surfactant gel appeared to stabilise the plasma membrane and demonstrated a resealing ability and helped to retain the plasma membrane integrity and enhanced wound healing.

Surfactants: Role in biofilm management and cellular behaviour

Appropriate and effective wound cleaning represents an important process that is necessary for preparing the wound for improved wound healing and for helping to dislodge biofilms. Wound cleaning is of paramount importance to wound bed preparation for helping to enhance wound healing. Surfactant applications in wound care may represent an important area in the cleaning continuum. However, understanding of the role and significance of surfactants in wound cleansing, biofilm prevention and control, and enhancing cellular viability and proliferation is currently lacking. Despite this, some recent evidence on poloxamer-based surfactants where the surfactants are present in high concentration have been shown to have an important role to play in biofilm management; matrix metalloproteinase modulation; reducing inflammation; and enhancing cellular proliferation, behaviour, and viability. Consequently, this review aims to discuss the role, mode of action, and clinical significance of the use of medically accepted surfactants, with a focus on concentrated poloxamer-based surfactants, to wound healing but, more specifically, the role they may play in biofilm management and effects on cellular repair.

Mode of action of poloxamer-based surfactants in wound care and efficacy on biofilms

Surfactants are widely used as detergents, emulsifiers, wetting agents, foaming agents, and dispersants in both the food and oil industry. Their use in a clinical setting is also common, particularly in wound care. Complicated or chronic wounds show clinical signs of delayed healing, persistent inflammation, and the production of non-viable tissue. These types of wounds also present challenges such as infection and potentially house antimicrobial-tolerant biofilms. The use of wound cleansers to aid cleaning and debridement of the wound is essential. A large proportion of skin and wound cleansers contain surfactants but there is only a small amount of data that shows the effectiveness of them in the enhancement of wound closure. This review paper aims to explore the available literature surrounding the use and mode of action of surfactants in wound healing, in particular Poloxamer 188 (Pluronic F-68) and Poloxamer 407 (Pluronic F-127), and also uncover the potential mechanisms behind the enhancement of wound healing and comparison to other surfactants used in wound care. Furthermore, the presence of a microbial biofilm in the wound is a significant factor in delayed wound healing. Therefore, the effect of clinically used surfactants on biofilms will be discussed, with emphasis on poloxamer-based surfactants.