Topical nanoemulsion therapy reduces bacterial wound infection and inflammation after burn injury

Novel griseofulvin zinc nanohybrid emulsion for intensifying the antimicrobial control of dermatophytes and some opportunistic pathogens

Dermatophytosis is a critical sort of skin infection caused by dermatophytes. The long-term treatment of such skin infections may be improved through the application of nanotechnology. This study aimed to prepare griseofulvin zinc Nanohybrid emulsion (GF-Zn-NHE) to improve griseofulvin activity against dermatophytes and some opportunistic pathogenic yeasts and bacteria. The GF-Zn-NHE is prepared by ultra-homogenization ultra-sonication strategies and validated by UV-visible spectroscopy analysis that confirms presences of griseofulvin and Zn-NPs peaks at 265 and 360 nm, respectively. The GF-Zn-NHE has mean distribution size 50 nm and zeta potential in the range from -40 to -36 mV with no significant changes in size distribution and particle size within 120 day ageing. Fourier transform infrared spectroscopy spectrum confirmed the presence of griseofulvin and Zn-NPs stretching vibration peaks. Gamma ray has a negative influence on GF-Zn-NE production and stability. GF-Zn-NHE drug release 95% up to 24 h and 98% up to 72 h of GF was observed and Zinc 90% up to 24 h and 95% up to 72 h, respectively. High antimicrobial activity was observed with GF-Zn-NHE against dermatophytic pathogens in compare with GF, GF-NE, zinc nitrate and ketoconazole with inhibition zone ranged from 14 to 36 mm. The results have shown that the MIC value for Cryptococcus neoformans, Prophyromonas gingivalis and Pseudomonas aeruginosa is 0.125 mg ml -1 and for Trichophyton rubrum, L. bulgaricus and Escherichia coli value is 0.25 mg ml -1 and for Candida albicans, Malassezia furfur and Enterococcus faecalis is 0.5 mg ml -1 and finally 1 mg ml -1 for Streptococcus mutans. TEM of treated Cryptococcus neoformans cells with GF-Zn-NHE displayed essentially modified morphology, degradation, damage of organelles, vacuoles and other structures.

Fabrication, assessment, and potential anti-bacterial activity of sandalwood oil nanoemulsion and its hand rub sanitizer

In the last decade, extensive research has been performed on developing hand sanitizers that can be used to eradicate the diseases that are caused due to poor hand hygiene. Essential oils possess antibacterial and antifungal properties and thus have great potential to replace the available antibacterial agents. In the present study, sandalwood oil-based nanoemulsion (NE) and sanitizer have been formulated and well characterized for their properties. Antibacterial activity was assessed using growth inhibition studies, agar cup, viability assay, etc. The sandalwood oil NE synthesized had oil to surfactant ratio of 1:0.5 (2.5% sandalwood oil and 0.5% Tween 80) and was observed to have a droplet diameter of 118.3 ± 0.92 nm, the zeta potential of - 18.8 ± 2.01 mV, and stability of 2 months. The antibacterial activity of sandalwood NE and sanitizer was evaluated against microorganisms. The antibacterial activity was assessed using the zone of inhibition value of sanitizer, which was in the range of 19 to 25 mm against all microorganisms. Morphological analysis showed distant changes in membrane shape and size and microorganisms' morphology. The synthesized NE was thermodynamically stable and efficient enough to be used in sanitizer, and the formulated sanitizer showed great antibacterial efficacy.

Emulgel based on fish skin collagen-microalgae-silver increased neovascularization and re-epithelialization of full thickness burn in rats

Deep skin burn represents a global morbidity and mortality problem, and the limitation of topical treatment agents has motivated research to development new formulations capable of preventing infections and accelerating healing. The aim of this work was to develop and characterize an emulgel based on collagen (COL) and gelatin (GEL) extracted from fish skin associated with Chlorella vulgaris extract (CE) and silver nitrate (AgNO3). COL and GEL were characterized by physicochemical and thermal analyses; and CE by electrophoresis and its antioxidant capacity. Three emulgels formulations were developed: COL (0.5%) + GEL (2.5%) (E1), COL+GEL+CE (1%) (E2), and COL+GEL+CE + AgNO3 (0.1%) (E3). All formulations were characterized by physicochemical, rheology assays, and preclinical analyses: cytotoxicity (in vitro) and healing potential using a burn model in rats. COL and GEL showed typical physicochemical characteristics, and CE presented 1.3 mg/mL of proteins and antioxidant activity of 76%. Emulgels presented a coherent physicochemical profile and pseudoplastic behavior. Preclinical analysis showed concentration-dependent cytotoxicity against fibroblast and keratinocytes. In addition, all emulgels induced similar percentages of wound contraction and complete wound closure in 28 days. The histopathological analysis showed higher scores for polymorphonuclear cells to E1 and greater neovascularization and re-epithelialization to E3. Then, E3 formulation has potential to improve burn healing, although its use in a clinical setting requires further studies.

Kinetics of Inflammatory Mediators in the Immune Response to Burn Injury: Systematic Review and Meta-Analysis of Animal Studies

Burns are often accompanied by a dysfunctional immune response, which can lead to systemic inflammation, shock, and excessive scarring. The objective of this study was to provide insight into inflammatory pathways associated with burn-related complications. Because detailed information on the various inflammatory mediators is scattered over individual studies, we systematically reviewed animal experimental data for all reported inflammatory mediators. Meta-analyses of 352 studies revealed a strong increase in cytokines, chemokines, and growth factors, particularly 19 mediators in blood and 12 in burn tissue. Temporal kinetics showed long-lasting surges of proinflammatory cytokines in blood and burn tissue. Significant time-dependent effects were seen for IL-1β, IL-6, TGF-β1, and CCL2. The response of anti-inflammatory mediators was limited. Burn technique had a profound impact on systemic response levels. Large burn size and scalds further increased systemic, but not local inflammation. Animal characteristics greatly affected inflammation, for example, IL-1β, IL-6, and TNF-α levels were highest in young, male rats. Time-dependent effects and dissimilarities in response demonstrate the importance of appropriate study design. Collectively, this review presents a general overview of the burn-induced immune response exposing inflammatory pathways that could be targeted through immunotherapy for burn patients and provides guidance for experimental set-ups to advance burn research.

Healing potential of curcumin nanomicelles in cutaneous burn wounds: an in vitro and in vivo study

PURPOSE/AIM OF THE STUDY

Curcumin is the active substance of turmeric and has been shown to enhance the healing potential of burn wounds. However, its high hydrophobicity and rapid degradability are great challenges for its clinical applications. The development of new curcumin formulations may provide a potential solution to these issues.

METHODS AND RESULTS

In this study, we investigated the use of curcumin nanomicelles for wound dressing and evaluated their effects on fibroblast migration and proliferation in vitro. We found that the application of curcumin nanomicelles to the wounds significantly improved wound contraction and increased the expression of transforming growth factor-1 and basic fibroblast growth factor at day 14 of the healing process. Furthermore, curcumin nanomicelles reduced the expression of interleukin-1 at days 7 and 14 post-wounding. Histopathological analysis revealed that the curcumin nanomicelles-treated burn wounds exhibited more organized granulation tissue, improved angiogenesis, and enhanced re-epithelialization. Additionally, the curcumin treatment led to increased hydroxyproline content and enhanced TGF-β1 expression level in the wounds. The in vitro studies also demonstrated that the curcumin nanomicelles induced proliferation and migration of fibroblasts.

CONCLUSION

Overall, our findings suggest that curcumin nanomicelles can be a promising candidate for the treatment of burn wounds.

Development of Nanotechnology-Based Drug Delivery Systems for Controlling Clinical Multidrug-Resistant Staphylococcus aureus and Escherichia coli Associated with Aerobic Vaginitis

The growing prevalence of resistance to antibiotics potentially makes Escherichia coli and Staphylococcus aureus serious pathogens, necessitating the development of new antimicrobial agents. We extracted crude biosurfactants from a potential probiotic Bacillus spp. to control pathogenic bacteria associated with aerobic vaginal infection. Using nanotechnology formulations, we developed nanoemulsions based on biosurfactants at different concentrations (1% and 3.33%). The results showed that these nanoemulsions were stable, with a weighted index of 0.3, and demonstrated broad-spectrum antibacterial activity against Escherichia coli and Staphylococcus aureus, with MICs ranging between 1.25 and 4 mg/mL. Additionally, the nanoemulsions exhibited interesting antibiofilm effects. All strains became more sensitive to the antibiotics to which they were resistant because of various biosurfactant formulations combined with antibiotics. Lower concentrations of BNE1% and 3.33% were still more efficient than the crude biosurfactants. Our findings demonstrated that the biosurfactant had a strong antibiofilm effect against all tested pathogens. This antibacterial effect can be explained by their ability to alter cell physiology such as cell hydrophobicity and membrane disintegration. Thus, we can conclude that the use of nanotechnology formulations has improved this effect, and the nanoemulsions developed in this study can be used as a potential anti-infectious therapy against multidrug-resistant bacterial strains of clinical origin.

Designing and characterization of curcumin-loaded nanotechnological dressings: A promising platform for skin burn treatment

Burns affect the skin and appendages, impair their function, and become favorable regions for bacterial infections. Owing to time-consuming and costly treatments, burns have been considered a public health problem. The limitations of the treatments used for burns have motivated the search for more efficient alternatives. Curcumin has several potential properties such as anti-inflammatory, healing, and antimicrobial activities. However, this compound is unstable and has low bioavailability. Therefore, nanotechnology could offer a solution for its application. This study aimed to develop and characterize dressings (or gauzes) impregnated with curcumin nanoemulsions that were prepared using two different techniques as a promising platform for skin burn treatment. In addition, the effect of cationization on curcumin release from the gauze was evaluated. Nanoemulsions were successfully prepared using two methods, ultrasound and a high-pressure homogenizer, with sizes of 135 nm and 144.55 nm, respectively. These nanoemulsions exhibited a low polydispersity index, adequate zeta potential, high encapsulation efficiency, and stability for up to 120 d. In vitro assays demonstrated a controlled release of curcumin between 2 and 240 h. No cytotoxicity was observed at concentrations of curcumin up to 75 µg/mL, and cell proliferation was observed. The incorporation of nanoemulsions in the gauze was successfully achieved, and the evaluation of curcumin release showed a faster release from cationized gauzes, whereas the non-cationized gauze promoted a more constant release.

Development of food-grade antimicrobials of fenugreek oil nanoemulsion-bioactivity and toxicity analysis

Antimicrobials of natural origin are proving to be an effective solution to emerging antimicrobial resistance and its physiological side effects. Recent studies have demonstrated that essential oils encapsulated in the form of nanoemulsions have better antimicrobial activity than the oil itself, possibly due to its high stability, solubility, sustained release, and increased bioavailability. In the present study, fenugreek oil-a well-known antimicrobial and antioxidant-has been used to fabricate nanoemulsion (NE), with an objective to meet potential alternative to synthesized antimicrobials. A combination of three different components, water, fenugreek oil, and Tween 80, has been used to prepare the nanoemulsions of different size and one of the most stable nanoemulsion with lowest concentration of surfactant Tween 80 was used to assess its bioactivity, antimicrobial properties, and toxicity against human hepatic cell line. Among all the formulations, nano-emulsion with 2.5% oil concentration, 30 min sonication (hydrodynamic size 135.2 nm, zeta potential 36.8 mV, PDI 0.135, and pH 5.12), was selected for all studies. The nanoemulsion showed potential antibacterial activity against all the microbial strains (Escherichia coli, Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa) used in this study. Interestingly, the nanoemulsion showed potential antibacterial activity against P. aeruginosa, known to show resistance against ampicillin. The toxicity evaluation in human hepatic cell line (WRL-68) indicated no significant toxicity of nanoemulsion up to the concentration of 800 µg/ml. The synthesized nanoemulsion thus has a translational potential as a food-grade non-toxic natural nanoantimicrobials.

Exploration of a W/O Nanoemulsion for Antibiofilm Activity against Cariogenic Enterococcus faecalis

A ciprofloxacin-loaded water-in-oil nanoemulsion (CPX-NE) was prepared and evaluated for the antimicrobial effect against oral biofilms produced by Enterococcus faecalis. CPX-NE was prepared by ultrasonication using functional excipients oleic acid (oil phase), Span 80 (surfactant), and Transcutol P (cosurfactant). Rheological parameters (viscosity = 20 ± 1.24 cp) confirmed optimum values for CPX-NE, a pH of 6.5 ± 0.23 suggested the simulation of CPX-NE with the pH of the mouth cavity, refractive index (1.46 ± 0.22), and % transmittance (92.34 ± 0.02) indicated the isotropic nature of the NE. The droplet size (72.19 ± 1.68 nm), polydispersity index (0.142 ± 0.02), and ζ potential (-28 mV) demonstrated a narrow size distribution and electrostatically stabilized NE. The morphology of the optimized formulation showed uniform spherical nanodroplets, as seen in fluorescence microscopy. In vitro drug release showed an initial burst effect followed by sustained release for 48 h, following Fick's diffusion. The minimum biofilm inhibitory and eradication concentration (MBIC/MBEC) was determined to compare CPX-NE with ciprofloxacin plain drug solution (CPX-PS) for their efficacy. CPX-NE demonstrated a significant inhibitory and eradication effect compared to CPX-PS. It was concluded that the developed CPX-NE has effective antibiofilm activity against E. faecalis and may be useful in the prevention and treatment of dental caries.

Iminated aminoglycosides in self-emulsifying drug delivery systems: Dual approach to break down the microbial defense

HYPOTHESIS

Aminoglycosides are well known, cationic antimicrobial drugs. However, biofilm-based antibiotic resistance significantly limits their efficacy. Masking the polycationic character of these drugs, followed by incorporation into self-emulsifying drug delivery systems (SEDDS) can improve biofilm eradication.

EXPERIMENTS

Imine derivatives were synthesized via coupling with trans-cinnamaldehyde and characterized regarding degree of substitution, logP, cytotoxicity and antimicrobial efficacy on the opportunistic human pathogens Escherichia coli, Staphylococcus aureus and Candida albicans. Imines were loaded into newly developed SEDDS formulations and the antimicrobial efficacy was assessed on these pathogens in planktonic state and after biofilm formation.

FINDINGS

Successful synthesis of imine derivatives with almost entirely masked amine groups was confirmed by NMR, FT-IR, TLC and MS. Imines exhibited a marked elevation in logP value of 8 units for kanamycin and 7.7 units for tobramycin. They showed low toxicity profiles while fully preserving antimicrobial efficacy on all tested pathogens. Incorporation into SEDDS resulted in nanoemulsions, which exhibited equal antimicrobial efficacy on the model germs compared to the corresponding aminoglycosides. Moreover, the biofilm eradication assay revealed superior anti-biofilm properties of the nanoemulsions. Native aminoglycosides were largely prone to reduced microbial susceptibility due to biofilm formation, while the combination of SEDDS with iminated aminoglycosides provided overall enhanced biofilm eradication.

Design and development of essential oil based nanoemulsion for topical application of triclosan for effective skin antisepsis

The skin acts as physical barrier to protect the body from external physical and chemical environment. When skin is infected, the outer epidermal barrier is compromised and colonized with microbial growth. Wound infection presents an immense burden in healthcare costs and decreased quality of life for patients. Topical application of nanoemulsions (NE) at pathological sites offers the potential advantage of direct drug delivery to the skin including potential for follicular targeting. This may have application in the improvement of skin antisepsis. In this study, NEs of triclosan (TSN) were prepared using hot high shear homogenization followed by ultrasonication. The oil phases comprised eucalyptus oil (EO) and olive oil (OO) and pseudo-ternary phase diagrams used to select optimum concentrations of surfactant. EO-based NEs had smaller droplet size and higher entrapment efficiency compared to OO-based NEs. Skin permeation was higher for EO-containing formulations, likely due to higher solubility of TSN in EO, smaller droplet size, low viscosity, and permeation enhancement effects of EO. Significantly, TSN was retained within the skin, demonstrating the potential of NEs for targeting hair follicular delivery within the skin, which may help improve the success of topical antisepsis.

Burn-Induced Local and Systemic Immune Response: Systematic Review and Meta-Analysis of Animal Studies

As burn injuries are often followed by a derailed immune response and excessive inflammation, a thorough understanding of the occurring reactions is key to prevent secondary complications. This systematic review, that includes 247 animal studies, shows the post-burn response of 14 different immune cell types involved in immediate and long-term effects, in both wound tissue and circulation. Peripheral blood neutrophil and monocyte numbers increased directly after burns, whereas thrombocyte numbers increased near the end of the first week. Lymphocyte numbers, however, were decreased for at least two weeks. In burn wound tissue, neutrophil and macrophage numbers accumulated during the first three weeks. Burns also altered cellular functions as we found increased migratory potential of leukocytes, impaired antibacterial activity of neutrophils and enhanced inflammatory mediator production by macrophages. Neutrophil surges were positively associated with burn size and were highest in rats. Altogether, this comprehensive overview of the temporal immune cell dynamics shows that unlike normal wound healing, burn injury induces a long-lasting inflammatory response. It provides a fundamental research basis to improve experimental set-ups, burn care and outcome.

A Pilot Study on the Effect of Thyme Microemulsion Compared with Antibiotic as Treatment of Salmonella Enteritidis in Broiler

Multidrug resistance poses a global threat to the poultry industry and public health, so the direction towards eliminating the use of antibiotics and finding alternatives is a vital step to solve this problem. Thyme microemulsion (10% oil/water) had nanodrop size 28.65 ± 0.89 nm, with a polydispersity index (PDI) of 0.28 with greater homogeneity. It showed IC₅₀ > 100 ug/ml on cytotoxicity assay and 14 active components by GC-Mass. The study was carried out using 210 Cobb chicks divided into fourteen groups. The infected groups were challenged using two Salmonella Enteritidis multidrug resistance (MDR) and Salmonella Enteritidis sensitive strains to the sulpha-trimethoprim antibiotic. The challenged inoculum was 1 × 10⁹ CFU of Salmonella Enteritidis by oral route. The MIC treatments doses were 1 ml/liter water for thyme oil and thyme microemulsion and 33.34 mg/kg b.wt sulfadiazine for 5 days. The results showed that both thymol oil (0.1%) and microemulsion (0.01%) are able to decrease the count of Salmonella Enteritidis in cecal content and fecal dropping and the mortality rates after five days of treatment. In addition, thyme oil and microemulsion had no pathological alteration on chickens' tissues that were collected two weeks after giving the treatment. By the robust HPLC method, the SDZ and TMP residues in tissues of infected groups treated with Cotrimazine® + thyme oil microemulsion had a slight significant economic impact (P < 0.05) compared to Cotrimazine® alone. In conclusion, thymol oil and microemulsion could be an alternative economic choice for multidrug resistance Salmonella Enteritidis treatment in poultry farms.

Nanoemulsion delivery systems for enhanced efficacy of antimicrobials and essential oils

The ever-growing threat of new and existing infectious diseases in combination with antimicrobial resistance requires the need for innovative and effective forms of drug delivery. Optimal drug delivery systems for existing and newly developed antimicrobials can enhance drug bioavailability, enable site-specific drug targeting, and overcome current limitations of drug formulations such as short elimination half-lives, poor drug solubility, and undesirable side effects. Nanoemulsions (NE) consist of nanometer-sized droplets stabilized by emulsifiers and are typically more stable and permeable due to their smaller particle sizes and higher surface area compared to conventional emulsions. NE have been identified as a promising means of antimicrobial delivery due to their intrinsic antimicrobial properties, ability to increase drug solubility, stability, bioavailability, organ and cellular targeting potentials, capability of targeting biofilms, and potential to overcome antimicrobial resistance. Herein, we discuss non-drug loaded essential oil-based NE that can confer antimicrobial actions through predominantly physical or biochemical mechanisms without drug payloads. We also describe drug-loaded NE for enhanced antimicrobial efficacy by augmenting the potency of existing antimicrobials. We highlight the versatility of NE to be administered through multiple different routes (oral, parenteral, dermal, transdermal, pulmonary, nasal, ocular, and rectal). We summarize recent advances in the clinical translation of antimicrobial NE and shed light on future development of effective antimicrobial therapy to combat infectious diseases.

Exploring the antibacterial, antibiofilm, and antivirulence activities of tea tree oil-containing nanoemulsion against carbapenem-resistant Serratia marcescens associated infections

Carbapenem-resistant Serratia marcescens (CRE-S. marcescens) has recently emerged as an opportunistic human pathogen that causes various nosocomial and respiratory tract infections. The prognosis for CRE-S. marcescens-related infections is very poor and these infections are difficult to treat. This study investigated the synthesis of tea tree oil nanoemulsion (TTO-NE) and its impact on CRE-S. marcescens both in vitro and in vivo. TTO-NE was characterized by dynamic light scattering (DLS) and effectively eradicated bacterial planktonic and sessile forms, reduced bacterial virulence factors, and generated reactive oxygen species (ROS) in the bacterial cell. Notably, TTO-NE was efficient in reducing the colonization of CRE-S. marcescens in a C. elegans in vivo model. The data suggest that TTO-NE might be an excellent tool to combat infections associated with CRE-S. marcescens.

Dermal Nanoemulsion Treatment Reduces Burn Wound Conversion and Improves Skin Healing in a Porcine Model of Thermal Burn Injury

Burn wound progression is an inflammation-driven process where an initial partial-thickness thermal burn wound can evolve over time to a full-thickness injury. We have developed an oil-in-water nanoemulsion formulation (NB-201) containing benzalkonium chloride for use in burn wounds that is antimicrobial and potentially inhibits burn wound progression. We used a porcine burn injury model to evaluate the effect of topical nanoemulsion treatment on burn wound conversion and healing. Anesthetized swine received thermal burn wounds using a 25-cm2 surface area copper bar heated to 80°C. Three different concentrations of NB-201 (10, 20, or 40% nanoemulsion), silver sulfadiazine cream, or saline were applied to burned skin immediately after injury and on days 1, 2, 4, 7, 10, 14, and 18 postinjury. Digital images and skin biopsies were taken at each dressing change. Skin biopsy samples were stained for histological evaluation and graded. Skin tissue samples were also assayed for mediators of inflammation. Dermal treatment with NB-201 diminished thermal burn wound conversion to a full-thickness injury as determined by both histological and visual evaluation. Comparison of epithelial restoration on day 21 showed that 77.8% of the nanoemulsion-treated wounds had an epidermal injury score of 0 compared to 16.7% of the silver sulfadiazine-treated burns (P = .01). Silver sulfadiazine cream- and saline-treated wounds (controls) converted to full-thickness burns by day 4. Histological evaluation revealed reduced inflammation and evidence of skin injury in NB-201-treated sites compared to control wounds. The nanoemulsion-treated wounds often healed with complete regrowth of epithelium and no loss of hair follicles (NB-201: 4.8 ± 2.1, saline: 0 ± 0, silver sulfadiazine: 0 ± 0 hair follicles per 4-mm biopsy section, P < .05). Production of inflammatory mediators and sequestration of neutrophils were also inhibited by NB-201. Topically applied NB-201 prevented the progression of a partial-thickness burn wound to full-thickness injury and was associated with a concurrent decrease in dermal inflammation.

Bacteria-Targeted MRI Probe-Based Imaging Bacterial Infection and Monitoring Antimicrobial Therapy In Vivo

Despite the significant advances of imaging techniques nowadays, accurate diagnosis of bacterial infections and real-time monitoring the efficacy of antibiotic therapy in vivo still remain huge challenges. Herein, a self-assembling peptide (FFYEGK) and vancomycin (Van) antibiotic molecule co-modified gadolinium (Gd) MRI nanoaggregate probe (GFV) for detecting Staphylococcus aureus (S. aureus) infection in vivo and monitoring the treatment of S. aureus-infected myositis by using daptomycin (Dap) antibiotic as model are designed and fabricated. The as-prepared GFV probe bears Van molecules, making itself good bacteria-specific targeting, and the peptide in the probe can enhance the longitudinal relaxivity rate (r₁ ) after self-assembly due to the π-π stacking. The study showed that, based on the GFV probe, bacterial infections and sterile inflammation can be discriminated, and as few as 10⁵ cfu S. aureus can be detected in vivo with high specificity and accurately. Moreover, the T₁ signal of GFV probe at the S. aureus-infected site in mice correlates with the increasing time of Dap treating, indicating the possibility of monitoring the efficacy of antibacterial agents for infected mice based on the as proposed GFV probe. This study shows the potential of GFV probe for diagnosis, evaluation, and prognosis of infectious diseases in clinics.

Recent advances in nanotherapeutics for the treatment of burn wounds

Moderate or severe burns are potentially devastating injuries that can even cause death, and many of them occur every year. Infection prevention, anti-inflammation, pain management and administration of growth factors play key roles in the treatment of burn wounds. Novel therapeutic strategies under development, such as nanotherapeutics, are promising prospects for burn wound treatment. Nanotherapeutics, including metallic and polymeric nanoformulations, have been extensively developed to manage various types of burns. Both human and animal studies have demonstrated that nanotherapeutics are biocompatible and effective in this application. Herein, we provide comprehensive knowledge of and an update on the progress of various nanoformulations for the treatment of burn wounds.

Lipid engineered nanoparticle therapy for burn wound treatment

INTRODUCTION

Skin is the largest organ of the human body protecting the underlying organs and tissues from any foreign attack. Any damage caused in the skin may sometimes result in serious consequences within the internal body tissues. Burn is one such issue that damage the layers of skin and thereby makingthe skin vulnerableand pronefor any foreign matter to enter and cause serious diseases.

METHODS

An online literature assessment was steered for the lipid nanoparticles, burn wound treatments, and different types of nanoformulation. Appropriate information was taken from different electronic scientific databases such as Web of Science, Elsevier, Science Direct, Springer, PubMed, Google Scholar etc.,Additional data was summarized from textbooks, local prints and scripts.

RESULTS

Recent innovations and developments in nanotechnology-based drug delivery systems has shown promising results in minimizing the drawbacks associated with conventional therapies. Lipid based nanoparticles possess capabilities to deliver active agents to their target site without the possibility of degradation. Conventional therapy of burn wound is costly and the treatment is long lasting, making the patient uncomfortable. Moreover, italso doesn't yield satisfactory results or narrow effects.Encapsulation of bioactives inside the lipid core protects the active entity from pH and enzymatic degradations.

CONCLUSION

This review highlights the drawbacks associated with the conventional dosage forms. A lot of consideration is focused on the advancement of nanomaterials using innovative methods in wound care for treating burn wounds with the faster healing effect.This review article highlights recent developments in lipid based nanoformulations for treatment of burn wound injury.

Nanotechnology-based lipid systems applied to resistant bacterial control: A review of their use in the past two decades

The rate of infections caused by resistant bacteria to the antimicrobials available for human use grows exponentially every year, which generates major impacts on human health and the world economy. In the last two decades, human beings can witness the expressive increase in the Science and Technology worldwide, and areas such as Health Sciences have benefited from these advances in favor of human health, such as the advent of Pharmaceutical Nanotechnology as an important approach applied for bacterial infections treatment with resistance profile to available antibiotics. This review of the scientific literature brings the applicability of nanotechnology-based lipid systems as an innovative tool in the improvement of bacterial infections treatment. Important studies involving the use of liposomes, solid lipid nanoparticles, nanostructured lipid carriers, nanoemulsions, microemulsions and lipid nanocapsules were verified in the period from 2000 to 2020, where important scientific results were found and will serve as a basis for the use of these systems to remain in constant updating. This manuscript shows the use of these drug delivery systems as potential vehicles for antibacterial compounds, which opens a new hope in the complement of the antibacterial therapeutic arsenal. Important studies developed in the last 20 years are present in this review, and thus guarantees an update on the use of these drug delivery systems for researchers from different areas of Health Sciences.

Topical Antiseptic Formulations for Skin and Soft Tissue Infections

Skin and soft tissue infections (SSTIs) are usually acute conditions of inflammatory microbial occupation of the skin layers and underlying soft tissues. SSTIs are one of the most frequent types of infection, typically requiring medical intervention and contribute to morbidity and mortality in both primary care and hospitalised patients. Due to the dramatic rise of antibiotic resistance, antiseptic agents can be potential alternatives for the prevention and treatment of SSTIs. Notably, they are commonly recommended in many global practical guidelines for use in per- and post- operative procedures. A range of antiseptics, including chlorhexidine, triclosan, alcohol, and povidone-iodine, are used and are mainly formulated as traditional, simple dosage forms such as solutions and semi-solids. However, in recent years, there have been studies reporting the potential for nanotechnology in the delivery of antiseptics. In this review, we have collated the scientific literature that focuses on topical antiseptic formulations for prevention and treatment of SSTIs, and have divided findings into traditional and advanced formulations. We conclude that although nanotechnological formulations have demonstrated potential advantages for delivering drugs; nevertheless, there is still scope for traditional formulations and further development of optimised topical formulations to address the rise of antimicrobial resistance.

Inorganic and Polymeric Nanoparticles for Human Viral and Bacterial Infections Prevention and Treatment

Infectious diseases hold third place in the top 10 causes of death worldwide and were responsible for more than 6.7 million deaths in 2016. Nanomedicine is a multidisciplinary field which is based on the application of nanotechnology for medical purposes and can be defined as the use of nanomaterials for diagnosis, monitoring, control, prevention, and treatment of diseases, including infectious diseases. One of the most used nanomaterials in nanomedicine are nanoparticles, particles with a nano-scale size that show highly tunable physical and optical properties, and the capacity to a wide library of compounds. This manuscript is intended to be a comprehensive review of the available recent literature on nanoparticles used for the prevention and treatment of human infectious diseases caused by different viruses, and bacteria from a clinical point of view by basing on original articles which talk about what has been made to date and excluding commercial products, but also by highlighting what has not been still made and some clinical concepts that must be considered for futures nanoparticles-based technologies applications.

Exploring Endolysin-Loaded Alginate-Chitosan Nanoparticles as Future Remedy for Staphylococcal Infections

Endolysins are a novel class of antibacterials with proven efficacy in combating various bacterial infections, in vitro and in vivo. LysMR-5, an endolysin derived from phage MR-5, demonstrated high lytic activity in our laboratory against multidrug-resistant S. aureus (MRSA) and S. epidermidis strains. However, endolysin and proteins in general are associated with instability and short in vivo half-life, consequently limiting their usage as pharmaceutical preparation to treat bacterial infections. Nanoencapsulation of endolysins could help to achieve better therapeutic outcome, by protecting the proteins from degradation, providing sustained release, thus could increase their stability, shelf life, and therapeutic efficacy. Hence, in this study, the feasibility of alginate-chitosan nanoparticles (Alg-Chi NPs) to serve as drug delivery platform for LysMR-5 was evaluated. LysMR-5-loaded nanoparticles were prepared by calcium ion-induced pre-gelation of alginate core and its complexation with chitosan. The formation of nanoparticles was confirmed on the basis of DLS, zeta potential, and electron microscopy imaging. The LysMR-5-loaded nanoparticles presented a hydrodynamic diameter of 276.5 ± 42, a PDI of 0.342 ± 0.02, a zeta potential - 25 mV, and an entrapment efficiency of 62 ± 3.1%. The potential ionic interaction between alginate, chitosan, and LysMR-5 was investigated by FT-IR and SEM-EDX analysis. Using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), nano-sized particles with characteristic morphology were seen. Different antibacterial assays and SDS-PAGE analysis showed no change in endolysin's structural integrity and bioactivity after entrapment. A direct antibacterial effect of blank Alg-Chi Nps, showing enhanced bactericidal activity upon LysMR-5 loading, was observed against S. aureus. At physiological pH (7.2), the release profile of LysMR-5 from Alg-Chi NPs showed a biphasic release and followed a non-Fickian release mechanism. The biocompatible nature as revealed by cytocompatibility and hemocompatibility studies endorsed their use as drug delivery system for in vivo studies. Collectively, these results demonstrate the potential of Alg-Chi NPs as nano-delivery vehicle for endolysin LysMR-5 and other therapeutic proteins for their use in various biomedical applications.

Comparison of a topical surfactant and a topical antibiotic in the rat comb burn model

BACKGROUND

Burn injury progression in the secondary zone of ischemia is common leading to delayed healing and increased scarring. We hypothesized that a topical surfactant, would reduce burn injury progression in a validated rat comb burn model compared with topical antibiotic ointment.

METHODS

We created 40 comb burns on 20 rats which were randomized to daily topical application of the surfactant or a triple antibiotic ointment. The comb burns consisted of 4 full thickness burns with 3 unburned interspaces between the 4 burns. These unburned interspaces represented the zone of ischemia, and when left untreated, generally progress to full thickness necrosis within several days. Comb burns were assessed daily for the presence of gross necrosis of the interspaces. At 7 days the comb burns were excised and blindly evaluated for the presence of histological evidence of necrosis. The study had 80% power to detect a 25% difference in the percentages of necrotic interspaces on day 7.

RESULTS

There were no differences in the percentages of histologically necrotic interspaces at 7 days in burns treated with the surfactant or antibiotic ointment (85% [95%CI, 74 to 92] vs. 75% [95%CI, 63 to 84]; mean difference 10% [95%CI -4 to 24]). There were also no between group differences in the percentages of grossly necrotic interspaces on any of the seven days of the experiment. The surfactant remained intact and adherent while the antibiotic had been absorbed at each daily dressing change.

CONCLUSIONS

A topical surfactant did not reduce injury progression in the rat comb burn model when compared with antibiotic ointment. The surfactant was more durable than the antibiotic ointment.

Antibacterial potential of essential oils of Zataria multiflora and Mentha piperita, micro- and nano-formulated forms

BACKGROUND AND OBJECTIVES

Plant-derived essential oils (EOs) shave many usages in health and medicine, such as antibacterial agents. The aim of this study was the improvement of antibacterial activities of two EOs using nanotechnology.

MATERIALS AND METHODS

Antibacterial activity was investigated on four important human pathogenic bacteria using the 96-well plate microdilution method, a quantitative approach. Eleven formulations were prepared using each of the EOs. Eventually, the best nanoformulation with the smallest particle size and polydispersive indices (PDI and SPAN) was selected using each EO for further investigations. Moreover, two microemulsions with similar ingredients and the same portion in comparison with two selected nanoemulsions were also prepared. Antibacterial activity of each EO was compared with its micro- and nano-emulsions.

RESULTS

The antibacterial efficacy of Zataria multiflora EO (ZMEO) was significantly better than Mentha piperita EO (MPEO). Besides, the antibacterial activity of nanoemulsion of ZMEO with a particle size of 129 ± 12 nm was significantly better than no- and micro-formulated forms of ZMEO. Interestingly, the efficiency of MPEO nanoemulsion (160 ± 25 nm) was also significantly better than MPEO and its micro-formulated form.

CONCLUSION

Regardless of the intrinsic antibacterial property of two examined EOs, by formulating to nanoemulsion, their efficiencies were improved. Nanoemulsion of ZMEO introduced as an inexpensive, potent and green antibacterial agent.

Nanoemulsion as an Effective Treatment against Human-Pathogenic Fungi

Infections triggered by pathogenic fungi cause a serious threat to the public health care system. In particular, an increase of antifungal drug-resistant fungi has resulted in difficulty in treatment. A limited variety of antifungal drugs available to treat patients has left us in a situation where we need to develop new therapeutic approaches that are less prone to development of resistance by pathogenic fungi. In this study, we demonstrate the efficacy of the nanoemulsion NB-201, which utilizes the surfactant benzalkonium chloride, against human-pathogenic fungi. We found that NB-201 exhibited in vitro activity against Candidaalbicans, including both planktonic growth and biofilms. Furthermore, treatments with NB-201 significantly reduced the fungal burden at the infection site and presented an enhanced healing process after subcutaneous infections by multidrug-resistant C. albicans in a murine host system. NB-201 also exhibited in vitro growth inhibition activity against other fungal pathogens, including Cryptococcus spp., Aspergillus fumigatus, and Mucorales Due to the nature of the activity of this nanoemulsion, there is a minimized chance of drug resistance developing, presenting a novel treatment to control fungal wound or skin infections.IMPORTANCE Advances in medicine have resulted in the discovery and implementation of treatments for human disease. While these recent advances have been beneficial, procedures such as solid-organ transplants and cancer treatments have left many patients in an immunocompromised state. Furthermore, the emergence of immunocompromising diseases such as HIV/AIDS or other immunosuppressive medical conditions have opened an opportunity for fungal infections to afflict patients globally. The development of drug resistance in human-pathogenic fungi and the limited array of antifungal drugs has left us in a scenario where we need to develop new therapeutic approaches to treat fungal infections that are less prone to the development of resistance by pathogenic fungi. The significance of our work lies in utilizing a novel nanoemulsion formulation to treat topical fungal infections while minimizing risks of drug resistance development.

Aspects of Nanomaterials in Wound Healing

Wound infections impose a remarkable clinical challenge that has a considerable influence on morbidity and mortality of patients, influencing the cost of treatment. The unprecedented advancements in molecular biology have come up with new molecular and cellular targets that can be successfully applied to develop smarter therapeutics against diversified categories of wounds such as acute and chronic wounds. However, nanotechnology-based diagnostics and treatments have achieved a new horizon in the arena of wound care due to its ability to deliver a plethora of therapeutics into the target site, and to target the complexity of the normal wound-healing process, cell type specificity, and plethora of regulating molecules as well as pathophysiology of chronic wounds. The emerging concepts of nanobiomaterials such as nanoparticles, nanoemulsion, nanofibrous scaffolds, graphene-based nanocomposites, etc., and nano-sized biomaterials like peptides/proteins, DNA/RNA, oligosaccharides have a vast application in the arena of wound care. Multi-functional, unique nano-wound care formulations have acquired major attention by facilitating the wound healing process. In this review, emphasis has been given to different types of nanomaterials used in external wound healing (chronic cutaneous wound healing); the concepts of basic mechanisms of wound healing process and the promising strategies that can help in the field of wound management.

Nanoemulsions and dermatological diseases: contributions and therapeutic advances

Skin disease is one of the most common human diseases and affects between 30% and 70% of individuals, which requires a lot of attention to their treatments. The delivery of active pharmacological ingredients at the topical level is a challenge because of the difficulties in overcoming the mechanical barrier created by the skin and reaching greater depths, since delivery specificities are decisive for the degree of effectiveness. In this way, the nanoemulsions emerge as a potential system for the incorporation of active substances in the cells and for the controlled release of active principles. The present article intends to review the main treatments for which the nanoemulsions were used in the field of dermatology. In addition, it discusses the results and advantages over the other dermatological therapies that are being used. The results showed that the particle size in nanoemulsions increased the contact surface area, resulting in increased drug efficacy, even in comparison with other existing pharmaceutical formulations. In conclusion, it has been shown that nanoemulsions have a better performance in efficacy, safety, permeability profile, and bioavailability compared with other formulations studied.

Cationic-bilayered nanoemulsion of fusidic acid: an investigation on eradication of methicillin-resistant Staphylococcus aureus 33591 infection in burn wound

AIM

The aim of the current study was to investigate the therapeutic efficacy of cationic-charged bilayered nanoemulsion for topical delivery of fusidic acid in eradicating methicillin-resistant Staphylococcus aureus (MRSA) bacterial burn wound infection.

MATERIALS & METHODS

The developed carriers were characterized for particle size, antibacterial activity, cell viability assay in HaCat cell lines, rheological profile, ex vivo and in vivo studies, namely, full thickness MRSA 33591 murine burn wound infection via topical route.

RESULTS

The developed cationic bilayered nanogel offered enhanced drug permeation, reduction in bacterial load and enhanced wound contraction along with faster re-epithelialization in burn wounds.

CONCLUSION

The results encourage the exploration of the potential of cationic nanogel in treating resistant microorganisms such as MRSA, especially for application in burn wound infection.

Nanoemulsion is an effective antimicrobial for methicillin-resistant Staphylococcus aureus in infected wounds

AIM

To develop NB-201, a nanoemulsion compound, as a novel microbicidal agent against methicillin-resistant Staphylococcus aureus (MRSA) infection, which is a common threat to public health but with limited therapeutic options.

MATERIALS & METHODS

NB-201 was tested in in vitro and in vivo murine and porcine models infected with MRSA.

RESULTS

Topical treatment of MRSA-infected wounds with NB-201 significantly decreased bacterial load and had no toxic effects on healthy skin tissues. NB-201 attenuated neutrophil sequestration in MRSA-infected wounds and inhibited epidermal and deep dermal inflammation. The levels of proinflammatory cytokines were reduced in NB-201-treated MRSA-infected wounds.

CONCLUSION

NB-201 can greatly reduce inflammation characteristic of infected wounds and has antimicrobial activity that effectively kills MRSA regardless of the genetic basis of antibiotic resistance.

EVALUATION OF EFFECTIVENESS IN A NOVEL WOUND HEALING OINTMENT-CROCODILE OIL BURN OINTMENT

Background:

Crocodile oil and its products are used as ointments for burns and scalds in traditional medicines. A new ointment formulation - crocodile oil burn ointment (COBO) was developed to provide more efficient wound healing activity. The purpose of the study was to evaluate the burn healing efficacy of this new formulation by employing deep second-degree burns in a Wistar rat model. The analgesic and anti-inflammatory activities of COBO were also studied to provide some evidences for its further use.

Materials and methods:

The wound healing potential of this formulation was evaluated by employing a deep second-degree burn rat model and the efficiency was comparatively assessed against a reference ointment - (1% wt/wt) silver sulfadiazine (SSD). After 28 days, the animals were euthanized and the wounds were removed for transversal and longitudinal histological studies. Acetic acid-induced writhing in mice was used to evaluate the analgesic activity and its anti-inflammatory activity was observed in xylene -induced edema in mice.

Results:

COBO enhanced the burn wound healing (20.5±1.3 d) as indicated by significant decrease in wound closure time compared with the burn control (25.0±2.16 d) (P<0.01). Hair follicles played an importance role in the physiological functions of the skin, and their growth in the wound could be revealed for the skin regeneration situation. Histological results showed that the hair follicles were well-distributed in the post-burn skin of COBO treatment group, and the amounts of total, active, primary and secondary hair follicles in post-burn 28-day skin of COBO treatment groups were more than those in burn control and SSD groups. On the other hand, the analgesic and anti-inflammatory activity of COBO were much better than those of control group, while they were very close to those of moist exposed burn ointment (MEBO).

Conclusions:

COBO accelerated wound closure, reduced inflammation, and had analgesic effects compared with SSD in deep second degree rat burn model. These findings suggest that COBO would be a potential therapy for treating human burns.

Abbreviations: COBO, crocodile oil burn ointment; SSD, silver sulfadiazine; MEBO, moist exposed burn ointment; TCM, traditional Chinese medicine; CHM, Chinese herbal medicine; GC-MS, gas chromatography-mass spectrometry.

In Vitro Anti-inflammatory and Antimicrobial Activities of Azithromycin After Loaded in Chitosan- and Tween 20-Based Oil-in-Water Macroemulsion for Acne Management

The objectives of the current investigation are (1) to prepare and characterize (particle size, surface charge (potential zeta), surface morphology by transmission electron microscopy, drug content, and drug release) the azithromycin (AZM, 100 mg)-loaded oil-in-water (o/w) macroemulsion, (2) to assess the toxicity of macroemulsion with or without AZM using RBC lysis test in comparison with AZM in phosphate buffer solution of pH 7.4, (3) to compare the in vitro antimicrobial activity (in Escherichia coli using zone inhibition assay) of AZM-loaded macroemulsion with its aqueous solution, and (4) to assess the in vitro anti-inflammatory effect (using egg albumin denaturation bioassay) of the AZM-loaded macroemulsion in comparison with diclofenac sodium in phosphate buffer solution of pH 7.4. The AZM-loaded macroemulsion possessed the dispersed oil droplets with a mean diameter value of 52.40 ± 1.55 μm. A reversal in the zeta potential value from negative (-2.16 ± 0.75 mV) to positive (+6.52 ± 0.96 mV) was noticed when AZM was added into the macroemulsion. At a 1:5 dilution ratio, 2.06 ± 0.03 mg of drug was released from macroemulsion followed by 1.01 ± 0.01 and 0.25 ± 0.08 mg, respectively, for 1:10 and 1:40 dilution ratios. Antimicrobial activity maintenance and significant reduction of RBC lysis property were noticed for AZM after loaded in the macroemulsion. However, an increment in the absorbance values for emulsion-treated samples in comparison to the control samples was noticed in the anti-inflammatory test. This speculates the potential of the AZM-loaded emulsion to manage inflammatory conditions produced at Acne vulgaris.

Nanoparticles for Control of Biofilms of Acinetobacter Species

Biofilms are the cause of 80% of microbial infections. Acinetobacter species have emerged as multi- and pan-drug-resistant bacteria and pose a great threat to human health. These act as nosocomial pathogens and form excellent biofilms, both on biotic and abiotic surfaces, leading to severe infections and diseases. Various methods have been developed for treatment and control of Acinetobacter biofilm including photodynamic therapy, radioimmunotherapy, prophylactic vaccines and antimicrobial peptides. Nanotechnology, in the present scenario, offers a promising alternative. Nanomaterials possess unique properties, and multiple bactericidal mechanisms render them more effective than conventional drugs. This review intends to provide an overview of Acinetobacter biofilm and the significant role of various nanoparticles as anti-biofouling agents, surface-coating materials and drug-delivery vehicles for biofilm control and treatment of Acinetobacter infections.

Enhanced efficacy and anti-biofilm activity of novel nanoemulsions against skin burn wound multi-drug resistant MRSA infections

Multi-drug resistant MRSA (methicillin-resistant Staphylococcus aureus) is a global problem for human health, especially skin burn wound patients. Therefore, we estimated the antibacterial and anti-biofilm activity of a chlorhexidine acetate nanoemulsion (CNE) by previously ourselves designed against skin burn wound MRSA infections. Compared with its water solution (CHX), CNE showed a better and faster action against MRSA both in vitro and in vivo. Importantly, CNE was more effective at inhibiting biofilm formation and clearing the biofilm. We also found that the cell walls and membranes of MRSA were severely disrupted after treatment with CNE. Moreover, the relative electrical conductivity and the leakage of alkaline phosphates, K(+), Mg(2+), DNA and protein obviously increased because the cell wall and membrane were damaged. These data show that novel CNE is a promising potential antimicrobial candidate, especially for skin burn wound MRSA infections.

Nanoemulsion Therapy for Burn Wounds Is Effective as a Topical Antimicrobial Against Gram-Negative and Gram-Positive Bacteria

The aim of this study is to investigate the antimicrobial efficacy of two different nanoemulsion (NE) formulations against Gram-positive and Gram-negative bacteria in an in vivo rodent scald burn model. Male Sprague-Dawley rats were anesthetized and received a partial-thickness scald burn. Eight hours after burn injury, the wound was inoculated with 1 × 10(8) colony-forming units of Pseudomonas aeruginosa or Staphylococcus aureus. Treatment groups consisted of two different NE formulations (NB-201 and NB-402), NE vehicle, or saline. Topical application of the treatment was performed at 16 and 24 hours after burn injury. Animals were killed 32 hours after burn injury, and skin samples were obtained for quantitative wound culture and determination of dermal inflammation markers. In a separate set of experiments, burn wound progression was measured histologically after 72 hours of treatment. Both NE formulations (NB-201 and NB-402) significantly reduced burn wound infections with either P. aeruginosa or S. aureus and decreased median bacterial counts at least three logs when compared with animals with saline applications (p < .0001). NB-201 and NB-402 also decreased dermal neutrophil recruitment and sequestration into the wound as measured by myeloperoxidase (MPO) assay and histopathology (p < .05). In addition, there was a decrease in the proinflammatory dermal cytokines (interleukin 1-beta [IL-1β], IL-6, and tumor necrosis factor alpha [TNF-α]) and the neutrophil chemoattractants CXCL1 and CXCL2. Using histologic examination, it was found that both NB-201 and NB-402 appeared to suppress burn wound progression 72 hours after injury. Topically applied NB-201 and NB-402 are effective in decreasing Gram-positive and Gram-negative bacteria growth in burn wounds, reducing inflammation, and abrogating burn wound progression.

Nanomedicines for Endothelial Disorders

The endothelium lines the internal surfaces of blood and lymphatic vessels and has a critical role in maintaining homeostasis. Endothelial dysfunction is involved in the pathology of many diseases and conditions, including disorders such as diabetes, cardiovascular diseases, and cancer. Given this common etiology in a range of diseases, medicines targeting an impaired endothelium can strengthen the arsenal of therapeutics. Nanomedicine - the application of nanotechnology to healthcare - presents novel opportunities and potential for the treatment of diseases associated with an impaired endothelium. This review discusses therapies currently available for the treatment of these disorders and highlights the application of nanomedicine for the therapy of these major disease complications.

Antibacterial activity of neem nanoemulsion and its toxicity assessment on human lymphocytes in vitro

Neem (Azadirachta indica) is recognized as a medicinal plant well known for its antibacterial, antimalarial, antiviral, and antifungal properties. Neem nanoemulsion (NE) (O/W) is formulated using neem oil, Tween 20, and water by high-energy ultrasonication. The formulated neem NE showed antibacterial activity against the bacterial pathogen Vibrio vulnificus by disrupting the integrity of the bacterial cell membrane. Despite the use of neem NE in various biomedical applications, the toxicity studies on human cells are still lacking. The neem NE showed a decrease in cellular viability in human lymphocytes after 24 hours of exposure. The neem NE at lower concentration (0.7-1 mg/mL) is found to be nontoxic while it is toxic at higher concentrations (1.2-2 mg/mL). The oxidative stress induced by the neem NE is evidenced by the depletion of catalase, SOD, and GSH levels in human lymphocytes. Neem NE showed a significant increase in DNA damage when compared to control in human lymphocytes (P<0.05). The NE is an effective antibacterial agent against the bacterial pathogen V. vulnificus, and it was found to be nontoxic at lower concentrations to human lymphocytes.

Antibiotic eluting clay mineral (Laponite®) for wound healing application: an in vitro study

Different materials in form of sponge, hydrogel and film have been developed and formulated for treating and dressing burn wounds. In this study, the potential of Laponite, a gel forming clay, in combination with an antimicrobial agent (mafenide), as a wound dressing material was tested in vitro. Laponite/mafenide (Lap/Maf) hydrogel was formulated in three different ratios of Lap/Maf 1:1, 1:2, 1:3. Laponite/mafenide/alginate (Lap/Maf/Alg) film was also formulated by combining Lap/Maf gel (1:1) with alginate. Intercalation rate of mafenide into the layers of Laponite nanoparticles and physico-chemical properties, including wound dressing characteristics of materials were studied using various analytical methods. Furthermore, the degradation of materials and the release profile of mafenide were investigated in simulated wound exudates fluid and antibacterial effectiveness of the eluted mafenide was tested on a range of bacterial species. The cytotoxicity of materials was also evaluated in skin fibroblast culture. The results showed that mafenide molecules were intercalated between the nano-sized layers of Laponite. The eluted mafenide showed active antibacterial effects against all three tested bacteria. All intercalated mafenide released from Lap/Maf 1:1 and 1:2 gel formulations and nearly 80% release from 1:3 formulation during test period. No significant difference was observed in release profile of mafenide between Lap/Maf/Alg film and Lap/Maf formulations. Wound dressing tests on Lap/Maf/Alg film showed it is a breathable dressing and has capacity to absorb wound exudates. The study showed that prepared Lap/Maf composite has the potential to be used as an antibiotic eluting gel or film for wound healing application. Additionally, Laponite has shown benefits in wound healing processes by releasing Mg(2+) ions and thereby reducing the cytotoxic effect of mafenide on fibroblast cells.

Animal models in burn research

Burn injury is a severe form of trauma affecting more than 2 million people in North America each year. Burn trauma is not a single pathophysiological event but a devastating injury that causes structural and functional deficits in numerous organ systems. Due to its complexity and the involvement of multiple organs, in vitro experiments cannot capture this complexity nor address the pathophysiology. In the past two decades, a number of burn animal models have been developed to replicate the various aspects of burn injury, to elucidate the pathophysiology, and to explore potential treatment interventions. Understanding the advantages and limitations of these animal models is essential for the design and development of treatments that are clinically relevant to humans. This review aims to highlight the common animal models of burn injury in order to provide investigators with a better understanding of the benefits and limitations of these models for translational applications. While many animal models of burn exist, we limit our discussion to the skin healing of mouse, rat, and pig. Additionally, we briefly explain hypermetabolic characteristics of burn injury and the animal model utilized to study this phenomena. Finally, we discuss the economic costs associated with each of these models in order to guide decisions of choosing the appropriate animal model for burn research.

Evaluation of a nisin-eluting nanofiber scaffold to treat Staphylococcus aureus-induced skin infections in mice

Staphylococcus aureus is a virulent pathogen and a major causative agent of superficial and invasive skin and soft tissue infections (SSSTIs). Antibiotic resistance in S. aureus, among other bacterial pathogens, has rapidly increased, and this is placing an enormous burden on the health care sector and has serious implications for infected individuals, especially immunocompromised patients. Alternative treatments thus need to be explored to continue to successfully treat infections caused by S. aureus, including antibiotic-resistant strains of S. aureus. In this study, an antimicrobial nanofiber wound dressing was generated by electrospinning nisin (Nisaplin) into poly(ethylene oxide) and poly(d,l-lactide) (50:50) blend nanofibers. Active nisin diffused from the nanofiber wound dressings for at least 4 days in vitro, as shown by consecutive transfers onto plates seeded with strains of methicillin-resistant S. aureus (MRSA). The nisin-containing nanofiber wound dressings significantly reduced S. aureus Xen 36 bioluminescence in vivo and viable cell numbers in a murine excisional skin infection model. The bacterial burden of wounds treated with nisin-containing nanofiber wound dressings was 4.3 × 10(2) CFU/wound, whereas wounds treated with control nanofiber wound dressings had 2.2 × 10(7) CFU/wound on the last day of the trial (day 7). Furthermore, the wound dressings stimulated wound closure of excisional wounds, and no adverse effects were observed by histological analysis. Nisin-containing nanofiber wound dressings have the potential to treat S. aureus skin infections and to potentially accelerate wound healing of excisional wounds.

Antimicrobial activity of nanoemulsion in combination with cetylpyridinium chloride in multidrug-resistant Acinetobacter baumannii

Acinetobacter baumannii has emerged as a serious problematic pathogen due to the ever-increasing presence of antibiotic resistance, demonstrating a need for novel, broad-spectrum antimicrobial therapeutic options. Antimicrobial nanoemulsions are emulsified mixtures of detergent, oil, and water (droplet size, 100 to 800 nm) which have broad antimicrobial activity against bacteria, enveloped viruses, and fungi. Here, we screened the antimicrobial activities of five nanoemulsion preparations against four Acinetobacter baumannii isolates to identify the most suitable preparation for further evaluation. Among them, N5, which contains 10% (vol/vol) Triton X-100, 25% (vol/vol) soybean oil, and 1% (wt/vol) cetylpyridinium chloride (CPC), showed the best efficacy against A. baumannii in both its planktonic and biofilm forms and was selected for further study. Our data demonstrate that, while the killing of planktonic forms of A. baumannii was due to the 1% CPC component of our nanoemulsions, the breakdown of biofilms was achieved via the emulsified oil and detergent fractions. Furthermore, we documented the effect of ethanol and NaCl in combination with N5 on planktonic A. baumannii. In killing curves of N5 combined with other agents (ethanol or NaCl), a synergistic effect of a ≥ 2-log decrease in CFU/ml was observed. The antibiofilm activity of N5 was confirmed via a cell proliferation test and scanning electron microscopy. The effects of exposure to severe environmental conditions, which simulates the field conditions in Iraq and Afghanistan, were evaluated, and this exposure did not affect the overall antimicrobial activity of N5. These studies lay a solid foundation for the utilization of nanoemulsions against the antibiotic-resistant forms of A. baumannii.