Bacteriology, inflammation, and healing: a study of nanocrystalline silver dressings in chronic venous leg ulcers

A prospective study on the efficacy of sequential treatment of technology Lipido-Colloid Impregnated with Silver and Technology Lipido-Colloid Nano-Oligosaccharide Factor in the management of venous leg ulcers

Background and Aims

Venous leg ulcers (VLUs) are associated with significant morbidity and poor quality of life (QOL). Compression therapy and wound dressing are the mainstay treatment options. Technology Lipido-Colloid Impregnated with Silver (TLC-Ag) reduces bacterial load and Technology Lipido-Colloid Nano-Oligosaccharide Factor (TLC-NOSF) reduces elevated matrix metalloproteinases and improve wound healing. However, evidence is scarce on the role of sequential therapy. This study aims to evaluate if sequential treatment with TLC-Ag and TLC-NOSF improves VLU wound healing and QOL.

Methods

This is a prospective cohort study from May 2020 to October 2021 on patients with VLUs who received sequential therapy, consisting of 2 weeks of TLC-Ag followed by two-layer compression bandage (2LB) with TLC-NOSF until complete wound healing. Participants were followed-up with weekly dressing changes. Our primary outcomes were wound area reduction (WAR) and Pressure Ulcer Scale of Healing (PUSH) score. Our secondary outcomes were QOL measures.

Results

There were 28 patients with 57.1% males (n = 16) with a mean age of 65.3 years. Mean duration of VLU was 13.9 ± 11.7 weeks before the initiation of sequential therapy. Mean baseline wound area was 8.44 cm2. Median time to wound healing was 10 weeks. 57.1% of patients achieved complete wound closure at 3 months. There was significant WAR after 1 month (mean area 8.44-5.81 cm2, 31.2% decrease) and after 3 months (mean area 8.44-2.53 cm2, 70.0% decrease). Mean monthly WAR was 28.9%. PUSH score also decreased at 1 month (16.5% decrease, p < 0.001) and 3 months (63.3% decrease, p < 0.001) marks following the sequential therapy. EuroQol Visual Analog Scale (EQ-VAS) improved following sequential therapy (baseline: 69.0 ± 15.0, week 13: 80.2 ± 13.2, p < 0.001).

Conclusion

Sequential therapy with TLC-Ag followed by TLC-NOSF and 2LB is feasible, with good wound healing and improvement in QOL of patients with VLUs.

Do Commonly Used Antimicrobial Topicals Facilitate Venous Leg Ulcer Healing?

OBJECTIVE

To survey which topical antimicrobials are most helpful in treating venous leg ulcers (VLUs).

DATA SOURCES

In this narrative review, the authors searched the databases of Google Scholar, Cochrane Library, and Wiley Online Library.

STUDY SELECTION

Studies were eligible for inclusion if they studied the effects of antimicrobial agents on chronic VLU healing and were published after 1985. Exceptions to this were in vitro studies of manuka honey and Dakin solution (Century Pharmaceuticals). Search terms included "venous leg ulcer", "nonhealing ulcer", "antimicrobial resistance", and "biofilms".

DATA EXTRACTION

Data extracted included design, setting, descriptions of intervention and control groups, outcomes, data collection tools, and potential harms.

DATA SYNTHESIS

A total of 19 articles encompassing 26 studies/trials met the inclusion criteria. Of the 26 studies, 17 were randomized controlled trials; the remaining 9 were a mix of lower-quality case series and comparative, nonrandomized, or retrospective studies.

CONCLUSION

Studies suggest that VLUs can be treated with multiple different topical antimicrobials. Depending on the extent of chronicity and bacterial colonization, some antimicrobials may be better suited than others.

Effect of four-layer dressing on the microbiological profile of venous leg ulcer

OBJECTIVE

Venous leg ulcer (VLU) is a chronic disease and has periods of exacerbation and remission. Various bandage systems-single-layered, double-layered and multiple-layered with elastic and non-elastic components-have been developed. The requirement for sustained pressure brought about the introduction of the four-layer bandage. We studied the bacteriology of VLUs and the effect of four-layer bandages on their healing.

METHOD

Clinical details of all patients, with wound size measurement by gauze piece, wax paper and scale, were recorded. The wounds were initially debrided and photographic records of all patients were maintained. Patients were followed up every week, when the dressings and four-layer bandages were changed.

RESULTS

A total of 60 patients were recruited to the study with four patients having bilateral disease and so a total of 64 VLUs were evaluated. Of these, 60 (93.8%) healed completely, one (1.6%) healed partially and three (4.7%) did not heal. After excluding the four VLUs that did not fully heal, 10 (16.7%) had recurrence while 50 (83.3%) had no recurrence in the follow-up period, which lasted for one year. During the first visit (baseline), meticillin-resistant Staphylococcus aureus (MRSA) was isolated in 29 (45.31%) VLUs and Pseudomonas spp. in 20 (31.25%) VLUs. With subsequent dressing, the VLU size decreased and the culture of the VLU was sterile from the third culture onwards in 45 cases. There was a significant correlation (p<0.001) between VLU size and the number of dressings.

CONCLUSION

Compression therapy is the mainstay of treatment of VLU, with rapid healing and improvement in bacteriological profile. Compression in the range of 30-40mmHg is the most effective treatment for uncomplicated VLUs with adequate arterial competency.

Green Synthesis and Characterization of Silver Nanoparticles Using Myrsine africana Leaf Extract for Their Antibacterial, Antioxidant and Phytotoxic Activities

Nanotechnology is the study and control of materials at length scales between 1 and 100 nanometers (nm), where incredible phenomena enable new applications. It affects all aspects of human life and is the most active research topic in modern materials science. Among the various metallic nanoparticles used in biomedical applications, silver nanoparticles (AgNPs) are among the most important and interesting nanomaterials. The aim of this study was to synthesize AgNPs from the leaf extract of Myrsine africana to investigate their antibacterial, antioxidant, and phytotoxic activities. When the leaf extract was treated with AgNO3, the color of the reaction solution changed from light brown to dark brown, indicating the formation of AgNPs. The UV-visible spectrum showed an absorption peak at 438 nm, confirming the synthesis of AgNPs. Scanning electron microscopy (SEM) showed that the AgNPs were spherical and oval with an average size of 28.32 nm. Fourier transform infrared spectroscopy confirms the presence of bio-compound functional groups on the surface of the AgNPs. The crystalline nature of the AgNPs was confirmed by XRD pattern. These biosynthesized AgNPs showed pronounced antibacterial activity against Gram-positive and Gram-negative bacteria, with higher inhibitory activity against Escherichia coli. At 40 µg/mL AgNPs, the highest antioxidant activity was obtained, which was 57.7% and an IC50 value of 77.56 µg/mL. A significant positive effect was observed on all morphological parameters when AgNPs were applied to wheat seedlings under constant external conditions at the different concentrations. The present study provides a cost-effective and environmentally friendly method for the synthesis of AgNPs, which can be effectively used in the field of therapeutics, as antimicrobial and diagnostic agents, and as plant growth promoters.

Nanobiotechnology: Applications in Chronic Wound Healing

Wounds occur when skin integrity is broken and the skin is damaged. With progressive changes in the disease spectrum, the acute wounds caused by mechanical trauma have been become less common, while chronic wounds triggered with aging, diabetes and infection have become more frequent. Chronic wounds now affect more than 6 million people in the United States, amounting to 10 billion dollars in annual expenditure. However, the treatment of chronic wounds is associated with numerous challenges. Traditional remedies for chronic wounds include skin grafting, flap transplantation, negative-pressure wound therapy, and gauze dressing, all of which can cause tissue damage or activity limitations. Nanobiotechnology — which comprises a diverse array of technologies derived from engineering, chemistry, and biology — is now being applied in biomedical practice. Here, we review the design, application, and clinical trials for nanotechnology-based therapies for chronic wound healing, highlighting the clinical potential of nanobiotechnology in such treatments. By summarizing previous nanobiotechnology studies, we lay the foundation for future wound care via a nanotech-based multifunctional smart system.

The antibacterial effect of nanosilver fluoride in relation to caries activity in primary teeth: a protocol for a randomized controlled clinical trial

Background

Minimally invasive dentistry is a highly convenient and efficient method of managing caries in pediatric patients. Silver diamine fluoride (SDF) is commonly used to arrest active caries lesions. However, the associated black stain, possibility of soft tissue injury, and unpleasant taste often limit its use. Recently, nanosilver fluoride (NSF) emerged as a promising topical fluoride agent with potent cariostatic and antibacterial potentials. This novel anticaries agent has gained attention as an alternative to overcome the drawbacks of SDF in caries arrest.

Objectives

To assess the antibacterial effect of NSF in relation to caries activity in dentin caries lesions, as well as to investigate the change in saliva bacterial levels in primary teeth in comparison to SDF after 1 and 3 months.

Materials and methods

Fifty children aged 4 to 6 years old with active dentin caries lesions (score 5 according to International Detection and Assessment System (ICDAS II) criteria) will be enrolled in the study. They will be equally and randomly allocated into 2 groups: a group receiving NSF and a control group receiving SDF treatment. Microbiological samples will be collected from the carious lesions and from unstimulated saliva at the baseline and at the 1 and 3 months’ follow-up appointments. Bacterial counts will be assessed using Mitis Salivarius agar (selective culture media for S. mutans) and Rogosa agar (selective culture media for lactobacilli), and the results will be expressed in colony-forming units. Data regarding the children’s oral health will be collected and their dmf index will be scored. The arrest of active carious lesions will be measured at the follow-up appointments according to ICDAS II criteria.

Results

The relation between bacterial colony counts and lesion activity for both groups will be assessed, as well as the change in salivary bacterial counts. The collected data will be statistically evaluated and tabulated. This clinical trial has been registered on ClinicalTrials.gov in January 2022 (original version) with ID: NCT05221749.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06477-5.

Synthesis approach-dependent antiviral properties of silver nanoparticles and nanocomposites

Numerous viral infections are common among humans, and some can lead to death. Even though conventional antiviral agents are beneficial in eliminating viral infections, they may lead to side effects or physiological toxicity. Silver nanoparticles and nanocomposites have been demonstrated to possess inhibitory properties against several pathogenic microbes, including archaea, bacteria, fungi, algae, and viruses. Its pronounced antimicrobial activity against various microbe-mediated diseases potentiates its use in combating viral infections. Notably, the appropriated selection of the synthesis method to fabricate silver nanoparticles is a major factor for consideration as it directly impacts antiviral efficacy, level of toxicity, scalability, and environmental sustainability. Thus, this article presents and discusses various synthesis approaches to produce silver nanoparticles and nanocomposites, providing technological insights into selecting approaches to generate antiviral silver-based nanoparticles. The antiviral mechanism of various formulations of silver nanoparticles and the evaluation of its propensity to combat specific viral infections as a potential antiviral agent are also discussed.

Green and Chemical Silver Nanoparticles and Pomegranate Formulations to Heal Infected Wounds in Diabetic Rats

Infected cutaneous ulcers from diabetic rats with Candida albicans and Streptococcus aureus were treated with spray formulations containing green silver nanoparticles (GS), chemical silver nanoparticles (CS), or pomegranate peel extract (PS). After wound development and infection, the treatments were performed twice per day for 14 days. The wound healing was analyzed on days 2, 7, and 14 through the determination of CFUs, inflammatory infiltrate, angiogenesis, fibroplasia, myeloperoxidase, and collagen determination. Expressive improvement in wound healing was noted using both silver nanoparticles for 7 days. All the treatments were superior to controls and promoted significant S. aureus reduction after 14 days. CS presented better anti-inflammatory results, and GS and CS the highest number of fibroblasts. Despite the techniques' limitations, GS and CS demonstrated considerable potential for managing infected wounds, especially considering no early strategies prior to the drugs, such as the debridement of these wounds, were included.

An Insight into Nano Silver Fluoride-Coated Silk Fibroin Bioinspired Membrane Properties for Guided Tissue Regeneration

The current work focuses on the development of a novel electrospun silk fibroin (SF) nonwoven mat as a GTR membrane with antibacterial, biomineralization and biocompatible properties. The γ-poly glutamic acid (γ-PGA)-capped nano silver fluoride (NSF) and silver diamine fluoride (SDF) were first synthesized, which were dip-coated onto electrospun silk fibroin mats (NSF-SF and SDF-SF). UV-Vis spectroscopy and TEM depicted the formation of silver nanoparticles. NSF-SF and SDF-SF demonstrated antibacterial properties (against Porphyromonas gingivalis) with 3.1 and 6.7 folds higher relative to SF, respectively. Post-mineralization in simulated body fluid, the NSF-SF effectively promoted apatite precipitation (Ca/P ~1.67), while the SDF-SF depicted deposition of silver nanoparticles, assessed by SEM-EDS. According to the FTIR-ATR deconvolution analysis, NSF-SF portrayed ~75% estimated hydroxyapatite crystallinity index (CI), whereas pure SF and SDF-SF demonstrated ~60%. The biocompatibility of NSF-SF was ~82% when compared to the control, while SDF-coated samples revealed in vitro cytotoxicity, further needing in vivo studies for a definite conclusion. Furthermore, the NSF-SF revealed the highest tensile strength of 0.32 N/mm and 1.76% elongation at break. Therefore, it is substantiated that the novel bioactive and antibacterial NSF-SF membranes can serve as a potential candidate, shedding light on further in-depth analysis for GTR applications.

Driveline exit-site care protocols in patients with left ventricular assist devices: a systematic review

 

OBJECTIVES

Driveline infections continue to be a significant complication following left ventricular assist device (LVAD) implantation. Driveline exit-site care is crucial for the prevention of infections; however, there are no uniform guidelines. The goal of this study was to provide an overview of the currently published driveline exit-site care protocols in patients with LVAD.

METHODS

A systematic literature review was performed. Studies before 15 December 2020 were included if the number of driveline infections was a primary outcome and the driveline exit-site care protocol was explained.

RESULTS

Eleven articles were included in the systematic review, including 1602 patients with LVADs. The median of the frequency of driveline infections in the articles was 13.8% with a range of 0–52.6%. There was a marked variability in the methods of care of driveline exit sites, without a standardized driveline dressing technique in patients with LVADs. The frequency of driveline infections was 6–7.5% in studies using a dressing kit that included chlorhexidine, a silver-based dressing and an anchoring device. Furthermore, there was variability in the anchoring devices and the frequency of dressing changes, which varied from daily to weekly. No specific anchoring device or change frequency was found to be superior.

CONCLUSIONS

Based on this systematic review, driveline exit care protocols that included chlorhexidine, a silver-based dressing, the use of an anchoring device and dressing kits might be best in reducing driveline infection rates. However, prospective studies with larger cohorts are needed to establish the optimal protocol for driveline exit-site care.

Mitigation of Obesity-Related Systemic Low-Grade Inflammation and Gut Microbial Dysbiosis in Mice with Nanosilver Supplement

Systemic low-grade inflammation and imbalance of gut microbiota are important risk factors promoting the progression of obesity-related metabolic disorders. This provides potential pharmacological and nutritional targets for the management of obesity and obesity-related disorders. Here, we evaluated the modulatory effects of nanosilver on obesity-related systemic low-grade inflammation and gut microbial dysbiosis. C57BL/6J mice were fed with normal diet (ND) or high-fat diet (HFD) for 6 months, with/without nanosilver supplementation in drinking water. Nanosilver administration showed little systemic toxicity and did not affect the progression of obesity but mitigated the obesity-related systemic low-grade inflammation in obese mice. Such mitigation of systemic low-grade inflammation was specifically mediated by reducing the inflammatory status of epididymal visceral white adipose tissue (eWAT). Nanosilver treatments increased the diversity of gut microbial communities and markedly recovered the relative abundance of Verrucomicrobia, Epsilonbacteraeota, Actinobacteria, and Deferribacteres, without altering the proportion of Bacteroidetes or Firmicutes. The beneficial effects of nanosilver in obese mice were in association with an increase in Akkermansia but a decrease in Parasutterella at the genus level. This study suggested a potential application of nanosilver in reducing the health risks of obesity.

Effect of Silver Nanoparticles on Healing of Third-Degree Burns Infected with Pseudomonas Aeruginosa in Laboratory Mice

The treatment of full-thickness skin burn using nanomaterials is promising as a medical application reducing the risk of infection and severe dermal scarring. Therefore, this study aims to evaluate the effectiveness of nanomaterials, particularly 3% silver nanoparticles containing ointment (3% SNO), on the full-thickness skin burn of laboratory mice. A total number of 36 male mice were used, equally divided into three groups: negative control (not burned and not treated); positive control (+ve) (burned and treated with castor oil and white petroleum jelly); and SNO-treated group (burned and treated with 3% SNO). The skin of the animals’ back was shaved. A 2x0.5 cm metal plate was heated on a burner to burn the skin of the animals of positive control and SNO-treated groups. Pseudomonas aeruginosa bacterial suspension was applied to the burnt area. The application of SNO, as well as the mixture of white petroleum jelly and castor oil, was started after 6 hours of inducing burns and continued for 14 days (three times daily) in the respected groups. The SNO-treated group showed accelerated healing within 14 days demonstrated by re-epithelialization of the epidermal layer and proliferation of the fibroblasts in the dermal layer. Less healing evidence was observed in the +ve control group in the same period. In conclusion, to our knowledge, this is the first study that uses a 3% SNO formula and has found that it has a promising impact on the treatment of infected skin burns.

Phyto-fabrication, purification, characterisation, optimisation, and biological competence of nano-silver

Published studies indicate that virtually any kind of botanical material can be exploited to make biocompatible, safe, and cost-effective silver nanoparticles. This hypothesis is supported by the fact that plants possess active bio-ingredients that function as powerful reducing and coating agents for Ag+. In this respect, a phytomediation method provides favourable monodisperse, crystalline, and spherical particles that can be easily purified by ultra-centrifugation. However, the characteristics of the particles depend on the reaction conditions. Optimal reaction conditions observed in different experiments were 70-95 °C and pH 5.5-8.0. Green silver nanoparticles (AgNPs) have remarkable physical, chemical, optical, and biological properties. Research findings revealed the versatility of silver particles, ranging from exploitation in topical antimicrobial ointments to in vivo prosthetic/organ implants. Advances in research on biogenic silver nanoparticles have led to the development of sophisticated optical and electronic materials with improved efficiency in a compact configuration. So far, eco-toxicity of these nanoparticles is a big challenge, and no reliable method to improve the toxicity has been reported. Therefore, there is a need for reliable models to evaluate the effect of these nanoparticles on living organisms.

Selective Laser Efficiency of Green-Synthesized Silver Nanoparticles by Aloe arborescens and Its Wound Healing Activities in Normal Wounded and Diabetic Wounded Fibroblast Cells: In vitro Studies

Introduction

Silver nanoparticles (AgNPs) have been extensively used in wound healing applications owing to their valuable physicochemical and biological properties. The main objective of this study was to evaluate the combined effects of green-synthesized silver nanoparticles (G-AgNPs) and photobiomodulation (PBM; laser irradiation at 830 nm with 5 J/cm²) in normal wounded and diabetic wounded fibroblast cells (WS1).

Methods

The combined effect of G-AgNPs and PBM was studied by various in vitro wound healing studies including cell morphology, cell migration rate and percentage wound closure, cell viability, cell proliferation, and filamentous (F)-actin and nuclear morphology staining.

Results

Cell viability results revealed good cellular compatibility of G-AgNPs to WS1 cells. The combined therapy of G-AgNPs and PBM demonstrated promising results to achieve progressive migration and wound closure in both normal wounded and diabetic wounded cell models. G-AgNPs alone and in combination with PBM had no negative effect on cell viability and proliferation, and there was an increase in cell migration.

Conclusion

Overall, these findings demonstrate that the combined treatment of G-AgNPs and PBM does not display any adverse effects on wound healing processes in both normal wounded and diabetic wounded cell models.

The effect of continuous diffusion of oxygen treatment on cytokines, perfusion, bacterial load, and healing in patients with diabetic foot ulcers

To evaluate continuous diffusion of oxygen therapy (CDO) on cytokines, perfusion, and bacterial load in diabetic foot ulcers we evaluated 23 patients for 3 weeks. Tissues biopsies were obtained at each visit to evaluate cytokines and quantitative bacterial cultures. Perfusion was measured with hyperspectral imaging and transcutaneous oxygen. We used paired T tests to compare continuous variables and independent T tests to compare healers and nonhealers. There was an increase from baseline to week 1 in TGF-β (P = .008), TNF-α (P = .014), VEGF (P = .008), PDGF (P = .087), and IGF-1 (P = .058); baseline to week 2 in TGF-β (P = .010), VEGF (P = .051), and IL-6 (P = .031); and baseline to week 3 with TGF-β (P = .055) and IL-6 (P = .054). There was a significant increase in transcutaneous oxygen after 1 week of treatment on both medial and lateral foot (P = .086 and .025). Fifty-three percent of the patients had at least a 50% wound area reduction (healers). At baseline, there were no differences in cytokines between healers and nonhealers. However, there was an increase in CXCL8 after 1 week of treatment (P = .080) and IL-6 after 3 weeks of treatment in nonhealers (P = .099). There were no differences in quantitative cultures in healers and nonhealers.

Modulatory effects of Cornus sanguinea L. mediated green synthesized silver nanoparticles on oxidative stress, COX-2/NOS2 and NFkB/pNFkB expressions in experimental inflammation in Wistar rats

The present study presents a green, cost efficient and easy synthesis method of silver nanoparticles (AgNPs) using an aqueous extract of Cornus sanguinea L. fruits (CS). The phytosynthesized silver nanoparticles were characterized using various analytical techniques such as UV-Vis absorption spectroscopy, which confirmed the formation of AgNPs and FTIR spectroscopy, in order to certify the role of the biomolecules present in the fruit extract as reducing and capping agents of the AgNPs. The UV-Vis absorption spectrum showed a broad band at 407 nm characteristic for colloidal silver. Transmission electron microscopy was conducted to investigate the shape and size of the silver nanoparticles, revealing a spherical shape with an average particle size of 18 nm. The antioxidant and anti-inflammatory activities of the fruit extract and green synthesized silver nanoparticles were assessed in vivo on experimental inflammation. The obtained results showed that CS and AgNPs reduced oxidative stress in parallel with increasing of antioxidant defense and diminished the COX-2 expressions. CS extract had a dual effect on NFkB activation depending on the time of testing while AgNPs increased NFkB phosphorylation at 48 h. These results suggested that both AgNPs and CS extract exhibited antioxidant and anti-inflammatory activities but with a different dynamics of action.

Synergetic Effect of Silver Nanoparticles and UVC Irradiation on H2AX Gene Expression in TK6 Cells

OBJECTIVE

The use of nanoscale particles, for instance silver nanoparticles (Ag NPs) has considerably increased recently. Since Ag NPs can be transmuted into silver ions; the toxicity and genotoxicity of these NPs along with other external factors such as ultraviolet type C (UVC) irradiation must be evaluated. In the present study, the aim was to investigate the genotoxic effects Ag NPs and UVC co-exposure on human lymphoblastoid TK6 cells.

MATERIALS AND METHODS

In this experimental study, Ag NPs (~20 nm) were purchased from US Research Nanomaterials Inc. and H2AX gene expression was evaluated using quantitative real time polymerase chain reaction (qRT-PCR), 1 and 24 hours post Ag NPs and UVC treatment.

RESULTS

Results showed that treatment of TK6 cells with different Ag NP concentrations without exposure to UVC can reduce H2AX gene expression, but treatment of these cells with Ag NPs in combination UVC irradiation can reduce viability that leads to a synergistic increase in the amount of H2AX gene expression.

CONCLUSION

According to our findings, Ag NPs can act to sensitize cells to UVC radiation when used for cancer treatment. So, combination of Ag NPs and UVC irradiation could be used in radiotherapy.

Injectable Scaffolds Enriched with Silver to Inhibit Bacterial Invasion in Tissue Regeneration

During wound healing, bacterial infections may prolong skin regeneration and tissue repair, causing delayed or incomplete healing. The therapeutic strategies currently used include general therapeutic modes, growth factors, skin substitutes, matrices and/or cell therapy. Among recent technologies, wound dressing materials comprising silver nitrate or silver sulfadiazine as the antimicrobial agent are widespread, despite their known cytotoxicity. The aim of this work was to develop and evaluate the efficacy of gelatinous injectable biomaterials composed of collagen and alginates, enriched with silver against bacterial pathogens commonly involved in wound infections. To reduce cytotoxicity, silver was used as lactate and saccharinated salts. Results show that silver-enriched beads were effective against both Gram-positive and Gram-negative strains in a concentration-dependent manner. Silver addition was more active against Staphylococcusepidermidis than against Pseudomonasaeruginosa. The antibacterial activity was localized only in the area of contact with the beads at concentrations lower than 0.3 mM, whereas at higher concentrations a larger inhibition halo was observed. No cytotoxic effect on eukaryotic cells was seen both testing the materials’ extracts or the Ag-doped beads in contact tests. These results, although preliminary, suggest that these scaffolds are a promising approach for realizing injectable or spreadable functional biomaterials with antibacterial activity for applications in wound management.

Autoclave-assisted synthesis of AgNPs in Z. officinale extract and assessment of their cytotoxicity, antibacterial and antioxidant activities

In this study, the authors synthesised silver nanoparticles (AgNPs) using autoclave as a simple, unique and eco-friendly approach. The effect of Zingiber officinale extract was evaluated as a reducing and stabiliser agent. According to transmission electron microscopy results, the AgNPs were in the spherical shape with a particle size of ∼17 nm. The biomedical properties of AgNPs as antibacterial agents and free radical scavenging activity were estimated. Synthesised AgNPs showed significant 1,1-diphenyl-2-picryl-hydrazyl free radical scavenging. Strong bactericidal activity was shown by the AgNPs on Gram-positive and Gram-negative bacteria. A maximum inhibition zone of ∼14 mm was obtained for epidermidis at a concentration of 60 μg/ml for sample fabricated at 24 h. The AgNPs also showed a significant cytotoxic effect against MCF-7 breast cancer cell lines with an half maximal inhibitory concentration value of 62 μg/ml in 24 h by the MTT assay. It could be concluded that Z. officinale extract can be used effectively in the production of potential antioxidant and antimicrobial AgNPs for commercial application.

Induction of 8-hydroxydeoxyguanosine and ultrastructure alterations by silver nanoparticles attributing to placental transfer in pregnant rats and fetuses

A quantitative assessment of the genotoxicity of silver nanoparticles (AgNPs) ascribed to its transplacental transfer and tissue distribution in pregnant rats was carried out in this study. A single intravenous (i.v.) injection of AgNPs with a size range from 4.0 to 17.0 nm was administered to pregnant rats at a dose of 2 mg/kg b.w. on the 19th day of gestation. Five groups beside control, each of the five rats were euthanized after 10 min, 1, 6, 12, or 24 h, respectively. The accumulation of nanoparticles (NPs) in mother and fetal tissues was quantified by inductively coupled plasma optical emission spectroscopy, where the highest accumulation level was recorded in maternal blood (0.523 µg/ml) after 24 h of administration. AgNPs induced accumulation in spleen tissue higher than placenta and fetal tissue homogenates. The data showed significantly detected levels of 8-hydroxydeoxyguanosine in all collected samples from administered animals compared with untreated individuals. Level of 8-OHdG in amniotic fluid exhibited the greatest values followed by maternal spleen, kidneys, and liver, respectively. Investigation by transmission electron microscope showed that the transfer of AgNPs through placental wall caused indentation of nuclei, clumped chromatin, pyknotic nuclei, and focal necrotic areas, while AgNPs appeared mainly accumulated in the macrophages of the spleen. Therefore, the data assume that the genotoxicity studies of AgNPs must be recommended during a comprehensive assessment of the safety of novel types of NPs and nanomaterials. Additionally, exposure to AgNPs must be prevented or minimized during pregnancy or prenatal periods.

UV-light mediated green synthesis of silver and gold nanoparticles using Cornelian cherry fruit extract and their comparative effects in experimental inflammation

The purpose of our study is to investigate the comparative effects of materials based on silver and gold nanoparticles functionalized with polyphenols from Cornus Mas extract (AgNPs-CM and AuNPs-CM) in vivo on experimental inflammation. The nanoparticles were obtained at room temperature under UV irradiation and were characterized by different methods: ultraviolet-visible spectroscopy, transmission electron microscopy, X ray diffraction, Fourier transform infrared spectroscopy and dynamic light scattering. The modulatory effects of AgNPs-CM and AuNPs-CM on inflammation were quantified by oxidative stress parameters, pro and anti-inflammatory cytokines levels and apoptosis assessment at 2 h, 24 and 48 h after induction of inflammation with carrageenan in the paw tissue of Wistar rats. Our results showed that silver and gold nanoparticles only partial and for a short period have mobilized the antioxidant defense mechanisms. In addition, they diminished inflammation and apoptosis in the early stage while later, at 48 h, exerted an immunomodulatory effect, activated ERK ½ and induced apoptosis. The photoreduced silver and gold nanoparticles, functionalized with natural compounds, modulated the inflammation in a similar manner in the soft tissue injected with carrageenan. In order to decipher the mechanisms involved in interactions of metallic nanoparticles with biological systems and for a complete assessment of the risks and benefits of these products in clinical practice long term studies are necessary.

Silver nanoparticles in situ synthesized by polysaccharides from Sanghuangporus sanghuang and composites with chitosan to prepare scaffolds for the regeneration of infected full-thickness skin defects

In recent years, silver nanoparticles have widely been used in antibacterial dressings to solve antibiotic resistance problems. However, traditional methods for reducing silver nanoparticles are usually toxic. To overcome this problem, Sanghuangporus sanghuang polysaccharides (FSHPs) were used as a green reducing agent to prepare silver nanoparticles (AgNPs) with a size of 3-35 nm. The FSHPs‑silver nanoparticles (FSHPs-Ag) composite with chitosan solution were then freeze-dried to obtain a porous sponge dressing of chitosan-FSHPs-Ag (CS-FSHPs-Ag). The internal pores of CS-FSHPs-Ag were between 50 and 100 μm and had good swelling and water retention properties, which could provide a moist environment for wounds. Based on the experimental results, the appropriate concentration of AgNPs required for CS-FSHPs-Ag to inhibit Escherichia coli and Staphylococcus aureus was determined. Moreover, there was no statistically significant difference between the material treatment and the blank control group, indicating that the material almost showed no toxicity to L929 cells. Finally, this material was used for dressing animal wounds. The results showed that the CS-FSHPs-Ag promoted wound contraction and internal tissue growth better than the wounds treated with Aquacel® Ag, which indicated that the CS-FSHPs-Ag has a great potential as an ideal wound dressing material.

Protease activity as a prognostic factor for wound healing in venous leg ulcers

BACKGROUND

Venous leg ulcers (VLUs) are a common type of complex wound that have a negative impact on people's lives and incur high costs for health services and society. It has been suggested that prolonged high levels of protease activity in the later stages of the healing of chronic wounds may be associated with delayed healing. Protease modulating treatments have been developed which seek to modulate protease activity and thereby promote healing in chronic wounds.

OBJECTIVES

To determine whether protease activity is an independent prognostic factor for the healing of venous leg ulcers.

SEARCH METHODS

In February 2018, we searched the following databases: Cochrane Central Register of Controlled Trials (CENTRAL), Ovid MEDLINE, Ovid Embase and CINAHL.

SELECTION CRITERIA

We included prospective and retrospective longitudinal studies with any follow-up period that recruited people with VLUs and investigated whether protease activity in wound fluid was associated with future healing of VLUs. We included randomised controlled trials (RCTs) analysed as cohort studies, provided interventions were taken into account in the analysis, and case-control studies if there were no available cohort studies. We also included prediction model studies provided they reported separately associations of individual prognostic factors (protease activity) with healing. Studies of any type of protease or combination of proteases were eligible, including proteases from bacteria, and the prognostic factor could be examined as a continuous or categorical variable; any cut-off point was permitted. The primary outcomes were time to healing (survival analysis) and the proportion of people with ulcers completely healed; the secondary outcome was change in ulcer size/rate of wound closure. We extracted unadjusted (simple) and adjusted (multivariable) associations between the prognostic factor and healing.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion at each stage, and undertook data extraction, assessment of risk of bias and GRADE assessment. We collected association statistics where available. No study reported adjusted analyses: instead we collected unadjusted results or calculated association measures from raw data. We calculated risk ratios when both outcome and prognostic factor were dichotomous variables. When the prognostic factor was reported as continuous data and healing outcomes were dichotomous, we either performed regression analysis or analysed the impact of healing on protease levels, analysing as the standardised mean difference. When both prognostic factor and outcome were continuous data, we reported correlation coefficients or calculated them from individual participant data.We displayed all results on forest plots to give an overall visual representation. We planned to conduct meta-analyses where this was appropriate, otherwise we summarised narratively.

MAIN RESULTS

We included 19 studies comprising 21 cohorts involving 646 participants. Only 11 studies (13 cohorts, 522 participants) had data available for analysis. Of these, five were prospective cohort studies, four were RCTs and two had a type of case-control design. Follow-up time ranged from four to 36 weeks. Studies covered 10 different matrix metalloproteases (MMPs) and two serine proteases (human neutrophil elastase and urokinase-type plasminogen activators). Two studies recorded complete healing as an outcome; other studies recorded partial healing measures. There was clinical and methodological heterogeneity across studies; for example, in the definition of healing, the type of protease and its measurement, the distribution of active and bound protease species, the types of treatment and the reporting of results. Therefore, meta-analysis was not performed. No study had conducted multivariable analyses and all included evidence was of very low certainty because of the lack of adjustment for confounders, the high risk of bias for all studies except one, imprecision around the measures of association and inconsistency in the direction of association. Collectively the research indicated complete uncertainty as to the association between protease activity and VLU healing.

AUTHORS' CONCLUSIONS

This review identified very low validity evidence regarding any association between protease activity and VLU healing and there is complete uncertainty regarding the relationship. The review offers information for both future research and systematic review methodology.

Appropriate use of dressings containing nanocrystalline silver to support antimicrobial stewardship in wounds

Antimicrobial resistance is an ever‐increasing global concern, with the era of untreatable infection becoming a reality. Wound care is no exception, with increasing issues of antibiotic‐resistant infections across different wound types and care settings. Antibiotic resistance and stewardship have been the priority for most strategic interventions so far; however, in wound care, alternative or supplementary strategies using antiseptics should be considered. Antiseptics such as silver can provide effective cidal activity across a broad range of wound pathogens, assuming they are used at the correct level for an appropriate duration. Evidence summarised in this manuscript suggests that effective antiseptics, such as nanocrystalline silver, have an increasing body of evidence in support of their use to minimise transmission of antibiotic‐resistant organisms as part of institutional infection control procedures and, in addition, through appropriate early use and stewardship on local wound infections, in conjunction with local procedures, to minimise the need for systemic antibiotic therapy. Engagement, alignment, and collaboration between wound care professionals and wider related teams and governments on antimicrobial stewardship, and the potential role of antiseptics within this, will help to generate further evidence for such interventions in the fight against antimicrobial‐resistant infections in wound care.

A Gold/Silver Hybrid Nanoparticle for Treatment and Photoacoustic Imaging of Bacterial Infection

Ag+ ions are a well-known antibacterial agent, and Ag nanoparticles act as a reservoir of these Ag+ ions for targeted therapy of bacterial infections. However, there are no tools to effectively trigger and monitor the release of Ag+ ions from Ag nanoparticles. Photoacoustic (PA) imaging is an emerging noninvasive imaging tool, and gold nanorods (AuNRs) are an excellent contrast agent for PA imaging. In this work, we developed Au/Ag hybrid nanoparticles by coating AuNRs with silver (Ag), which decreased their photoacoustic signal. The as-prepared, Ag-coated Au nanorods (Au/AgNRs) are stable under ambient conditions, but the addition of ferricyanide solution (1 mM) results in oxidative etching of the silver shell. The PA contrast is simultaneously recovered as the silver is released, and this PA signal offers noninvasive monitoring of localized release of Ag+ ions. The released Ag+ ions exhibit a strong bactericidal efficacy similar to equivalent free Ag+ ions (AgNO3), and the nanoparticles killed >99.99% of both (Gram-positive) methicillin-resistant Staphylococcus aureus (MRSA, 32 μM Ag+ equivalent) and (Gram-negative) Escherichia coli (8 μM Ag+ equivalent). The theranostic potential of these nanoparticles was demonstrated in a pilot in vivo study. Mice were inoculated with MRSA and Au/AgNRs were subcutaneously implanted followed by silver etching. There was a 730% increase in the PA signal ( p < 0.01) pre- and post-etching, and the bacterial counts in infected tissues of the treated group were reduced by 1000-fold (log CFU/g = 4.15 vs 7.75) versus the untreated control; this treatment efficacy was confirmed with histology. We further showed that these hybrid nanoparticles could release Ag+ after stimulation by reactive oxygen species including hydrogen peroxide and peroxynitrite. These hybrid Au/Ag nanoparticles are a useful theranostic agent for the photoacoustic imaging and treatment of bacterial infections.

Silver absorption and toxicity evaluation of silver wound dressings in 40 patients with chronic wounds

BACKGROUND

Silver-containing dressings are considered to be safe even though there have been some reports of complications, including argyria and various organ system dysfunctions. Despite the widespread use of silver dressings, little research has been done regarding the absorption and toxicity of silver.

OBJECTIVE

We aimed to study the systemic absorption of silver in patients with chronic inflammatory wounds and to determine associated factors of systemic silver absorption and evaluated its association with silver toxicity.

PATIENTS AND METHOD

Prospective, longitudinal, observational, multicentre, open-label pilot study. Patients from the Dermatology Departments of Lorraine (France) with the following inclusion criteria: (i) a chronic wound of more than 6 weeks and (ii) an ulcer needing silver-containing dressing were included. Before and after 28 days of treatment, clinical characteristics of the wound were recorded; hemogram, hepatic and renal functions, albumin sera and serum silver level were measured.

RESULTS

Half of the cases displayed raised levels of silver after 1 month of treatment. Predictive factors for systemic silver absorption were wound area, anaemia and malnutrition with anaemia and malnutrition confirmed on multivariate analysis. Wound vascularization may also play a role, as a higher absorption was observed in cases of wound granulation without arterial components. No toxicity was detected. This work has also emphasized the slow elimination of silver from the body.

CONCLUSION

Both long-term application and iterative treatments with silver dressings should be discouraged, especially in the elderly, who often suffer from malnutrition and anaemia to avoid potential cumulative toxicity.

Therapeutic effect of Aloe vera and silver nanoparticles on acid-induced oral ulcer in gamma-irradiated mice

Radiation combined injury, a life-threatening condition, has higher mortality than simple radiation injury. The aim of the present study was to analyze the efficiency of Aloe vera and silver nanoparticles in improving the healing of ulcerated oral mucosa after irradiation. Thirty male Albino mice were divided into five groups: control, radiation, Aloe vera (AV), silver nanoparticles (NS), and AV+NS. The mice were exposed to whole body 6Gy gamma-radiation. After one hour, 20% acetic acid was injected into the submucosal layer of the lower lip for ulcer induction. The animals received topical treatment with the assigned substances for 5 days. Lip specimens were subjected to hematoxylin and eosin and anti alpha-smooth muscle actin immunohistochemical staining. Results demonstrated occurance of ulcer three days post irradiation in all groups except in the AV+NS group where only epithelial detachment was developed. After seven days, data revealed persistent ulcer in radiation group, and almost normal epithelium in the AV+NS group. A significant reduction of epithelial thickness was detected in all groups at the third day as compared to control. At the seventh day, only the AV+NS group restored the epithelial thickness. Area percent of alpha-smooth muscle actin expression was significantly decreased in radiation group at the third day followed by significant increase at the seventh day. However, all treatment groups showed significant increase in alpha-smooth muscle actin at the third day, which decreased to normal level at the seventh day. Our study demonstrated the efficiency of Aloe vera and silver nanoparticles in enhancing ulcer healing after irradiation.

Nanosilver: new ageless and versatile biomedical therapeutic scaffold

Silver nanotechnology has received tremendous attention in recent years, owing to its wide range of applications in various fields and its intrinsic therapeutic properties. In this review, an attempt is made to critically evaluate the chemical, physical, and biological synthesis of silver nanoparticles (AgNPs) as well as their efficacy in the field of theranostics including microbiology and parasitology. Moreover, an outlook is also provided regarding the performance of AgNPs against different biological systems such as bacteria, fungi, viruses, and parasites (leishmanial and malarial parasites) in curing certain fatal human diseases, with a special focus on cancer. The mechanism of action of AgNPs in different biological systems still remains enigmatic. Here, due to limited available literature, we only focused on AgNPs mechanism in biological systems including human (wound healing and apoptosis), bacteria, and viruses which may open new windows for future research to ensure the versatile application of AgNPs in cosmetics, electronics, and medical fields.

Silver nanoparticles reduce the apoptosis induced by tumor necrosis factor-α

Silver nanoparticles (AgNPs) are widely known to have anti-inflammatory properties, but the exact mechanism underlying this anti-inflammatory effect is not clearly understood. Tumor necrosis factor-α (TNFα) is a major pro-inflammatory cytokine that is expressed in the early stage of cell inflammation and induces apoptosis by several known pathways. Our study aimed to investigate the effect of AgNPs on the response of lung epithelial cells to TNFα and the molecular mechanism of this response. Lung epithelial cell line NCI-H292 cells were exposed to AgNPs (5 µg/mL) and/or TNFα (20 ng/mL) for 24 h, then cellular uptake was analyzed using flow cytometry. Our results showed that AgNPs were taken up by cells in a dose-dependent manner and that the cellular uptake ratio of AgNPs was significantly increased in the presence of TNFα. Apoptosis assays indicated that exposure to AgNPs significantly decreased the apoptotic effect of TNFα. Confocal microscopy was used to localize the tumor necrosis factor receptor 1 (TNFR1) and revealed that TNFR1 localized on the surface of cells exposed to TNFα. In contrast, TNFR1 localized inside cells exposed to both AgNPs and TNFα, with very few receptors scattered on the cell membrane. The results indicated that AgNPs reduced the cell surface TNFR1 expression level. The results suggested that the reduction of surface TNFR1 reduced cellular response to TNFα, resulting in an anti-apoptotic effect.

Mechanisms Underlying Neurotoxicity of Silver Nanoparticles

The potent antimicrobial properties of nanoparticulate silver (AgNPs) have led to broad interest in using them in a wide range of commercial and medical applications. Although numerous in vivo and in vitro studies have provided evidence of toxic effects, rapid commercialization of AgNP-based nanomaterials has advanced without characterization of their potential environmental and health hazards. There is evidence that AgNPs can be translocated from the blood to the brain, regardless the route of exposure, and accumulate in the brain over time. As the brain is responsible for basic physiological functions and controls all human activities, it is important to assess the hazardous influence of AgNPs released from widely used nanoproducts and possible side effects of AgNP-based therapies. A number of studies have suggested that the size, shape and surface coating, as well as rates of silver ion release and interactions with proteins are the key factors determining the neurotoxicity of AgNPs. AgNPs target endothelial cells forming the blood-brain barrier, neurons and glial cells and leads finally to oxidative stress-related cell death. In this chapter, we review in detail current data on the impact of AgNPs on the central nervous system and discuss the possible mechanisms of their neurotoxic effects.

Synthesis of Nanosilver Particles in the Texture of Bank Notes to Produce Antibacterial Effect

Silver particles show antibacterial and antiseptic properties at the nanoscale. Such properties result from an alteration in the binding capacity of silver atoms in bits of less than 6.5[Formula: see text]nm which enables them to kill harmful organisms. Silver nanoparticles are now the most broadly used agents in the area of nanotechnology after carbon nanotubes. Given that currency bills are one of the major sources of bacterial disseminations and their contamination has recently been nominated as a critical factor in gastrointestinal infections and possibly colon cancers, here we propose a new method for producing antibacterial bank notes by using silver nanoparticles. Older bank notes are sprayed with acetone to clean the surface. The bank note is put into a petri-dish containing a solution of silver nitrate and ammonia so that it is impregnated. The bank notes are then reduced with the formaldehyde gas, which penetrates its texture and produces silver nanoparticles in the cellulose matrix. The side products of the reactions are quickly dried off and the procedure ends with the drying of the bank note. The transmission electron microscope (TEM) images confirmed the nanoscale size range for the formed particles while spectroscopy methods, such as XRD, provided proof for the metallic nature of the particles. Bacterial challenge tests then showed that no colonies of the three tested bacterium (Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa survived on the sample after a 72[Formula: see text]h incubation period. This study has provided a method for synthesizing silver NPs directly into the texture of fabrics and textiles (like that of bank notes) which can result in lower production costs, making the use of silver NPs economically beneficial. The method, specifically works on the fabric of bank notes, suggesting a method to tackle the transmission of bacteria through bank notes. Moreover, this study is a testament to the strong antibacterial nature of even low concentrations of silver NPs.

The Role of Topical Antiseptic Agents Within Antimicrobial Stewardship Strategies for Prevention and Treatment of Surgical Site and Chronic Open Wound Infection

Scope and Significance: The topical use of antiseptics for wound care has a role in an antimicrobial stewardship strategy. However, the details of this role need clarification. Further clinical research into the use of topical antiseptics in wound care would lower the risk of furthering antibiotic resistance and contribute to more effective antibiotic use. As part of this research, experimental and surveillance data are needed on the resistance and tolerance patterns associated with topical antiseptic use in wound infections. Objective: The development of antibiotic resistance presents global challenges in terms of patient harm and increased healthcare costs. The treatment of "at risk" and infected wounds contributes to this conundrum. Synergies between antibiotics and antiseptics and their appropriate combined use need exploration. Approach: A review of available evidence on the appropriateness of antiseptics as a fundamental component of antimicrobial stewardship strategies has been undertaken. Innovation: Opening up new ways of thinking and identifying gaps of knowledge will lead to optimizing justification of antimicrobial choices and combinations. This may lead to changes in practice in terms of solutions for the prevention and treatment of wound infection. Conclusion: Antiseptics are an integral part of antimicrobial stewardship strategies for the prevention and treatment of surgical site and chronic open wound infections.

Validation of a Screening Questionnaire for Chronic Leg Ulcers

The use of a validated screening questionnaire to identify individuals with chronic leg ulcers allows large-scale population-based studies to be conducted that measure and monitor the prevalence of the disease. The aim of this study was to design and validate such a screening questionnaire to identify patients with chronic leg ulcers. A simple 3-item questionnaire was developed at the Department of Dermatology, University Hospital of Zealand, Denmark. In total, 90 patients attending the department’s outpatient clinic for dermatological diseases and chronic wounds were included in this study. All included participants completed the questionnaire and were subsequently examined by dermatologists. We found that the constructed 3-item questionnaire in this study had a sensitivity and specificity of 95% and 93% and a positive predictive value and negative predictive value of 78% and 95%, respectively. Moreover, we found that the use of the 3-item questionnaire, as compared with a single question, in which the participants were asked whether they currently have a leg ulcer, resulted in significantly higher positive predictive value (+11.6%, P = .035) and specificity (+5.6%, P = .046) of the diagnostic test. Future studies are merited to investigate the diagnostic accuracy of the questionnaire in other populations and settings.

Evaluation of the wound healing efficacy of chemical and phytogenic silver nanoparticles

Wound healing requires a series of cellular events and a cascade of co-ordinated and systemic biochemical events. Silver nanoparticles possess many beneficial properties for wound management including antibacterial, anti-inflammatory and pro-healing properties. In this study, the authors investigated the wound healing properties of Cinnamomum verum extract mediated nanosilver (CENS) particles in comparison with 1% povidone iodine, citrate mediate NS and CE treatments. The topical application of CENS showed good antibacterial activity and accelerated wound healing with complete epithelialisation and normal re-growth of hair in all three models of study: namely, excision, incision and dead space models in rats compared with all other treatments. CENS was also found to promote collagen synthesis, stabilise wound besides countering oxidative stress and stimulating cellular proliferation CENS could be a novel therapeutic agent for wound management.

Cytotoxic and sublethal effects of silver nanoparticles on tendon-derived stem cells - implications for tendon engineering

Tendon injuries occur commonly in sports and workplace. Tendon-derived stem cells (TDSCs) have great potential for tendon healing because they can differentiate into functional tenocytes. To grow TDSCs properly in vivo, a scaffold is needed. Silver nanoparticles (AgNPs) have been used in a range of biomedical applications for their anti-bacterial and -inflammatory effects. AgNPs are therefore expected to be a good scaffolding coating material for tendon engineering. Yet, their cytotoxicity in TDSCs remains unknown. Moreover, their sublethal effects were mysterious in TDSCs. In our study, decahedral AgNPs (43.5 nm in diameter) coated with polyvinylpyrrolidone (PVP) caused a decrease in TDSCs' viability beginning at 37.5 μg ml-1 but showed non-cytotoxic effects at concentrations below 18.8 μg ml-1. Apoptosis was observed in the TDSCs when higher doses of AgNPs (75-150 μg ml-1) were used. Mechanistically, AgNPs induced reactive oxygen species (ROS) formation and mitochondrial membrane potential (MMP) depolarization, resulting in apoptosis. Interestingly, treating TDSCs with N-acetyl-l-cysteine (NAC) antioxidant significantly antagonized the ROS formation, MMP depolarization and apoptosis indicating that ROS accumulation was a prominent mediator in the AgNP-induced cytotoxicity. On the other hand, AgNPs inhibited the tendon markers' mRNA expression (0-15 μg ml-1), proliferation and clonogenicity (0-15 μg ml-1) in TDSCs under non-cytotoxic concentrations. Taken together, we have reported here for the first time that the decahedral AgNPs are cytotoxic to rat TDSCs and their sublethal effects are also detrimental to stem cells' proliferation and tenogenic differentiation. Therefore, AgNPs are not a good scaffolding coating material for tendon engineering.

Polyvinyl pyrrolidone/carrageenan blend hydrogels with nanosilver prepared by gamma radiation for use as an antimicrobial wound dressing

Hydrogels were prepared using polyvinyl pyrrolidone (PVP) blended with carrageenan by gamma irradiation at different doses of 25 and 40 kGy. Gel fraction of hydrogels prepared using 10 and 15% PVP in combination with 0.25 and 0.5% carrageenan was evaluated. Based on gel fraction, 15% PVP in combination with 0.25% carrageenan and radiation dose of 25 kGy was selected for the preparation of hydrogels with nanosilver. Radiolytic synthesis of silver nanoparticles within the PVP hydrogel was carried out. The hydrogels with silver nanoparticles were assessed for antimicrobial effectiveness and physical properties of relevance to clinical performance. Fluid handling capacity (FHC) for PVP/carrageenan was 2.35 ± 0.39-6.63 ± 0.63 g/10 cm(2) in 2-24 h. No counts for Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, and Candida albicans were observed in the presence of hydrogels containing 100 ppm nanosilver after 3-6 h. The release of silver from hydrogels containing 100 ppm nanosilver was 20.42 ± 1.98 ppm/100 cm(2) in 24 h. Hydrogels containing 100 ppm nanosilver with efficient FHC demonstrated potential microbicidal activity (≥3 log10 decrease in CFU/ml) against wound pathogens, P. aeruginosa, S. aureus, E. coli, and C. albicans. PVP/carrageenan hydrogels containing silver nanoparticles can be used as wound dressings to control infection and facilitate the healing process for burns and other skin injuries.

Curbing Inflammation in Skin Wound Healing: A Review

Wound healing is a complex regulated process that results in skin scar formation in postnatal mammals. Chronic wounds are major medical problems that can confer devastating consequences. Currently, there are no treatments to prevent scarring. In the early fetus wounds heal without scarring and the healing process is characterized by relatively less inflammation compared to adults; therefore, research aimed at reducing the inflammatory process related to wound healing might speed healing and improve the final scar appearance.

Nanocarriers in therapy of infectious and inflammatory diseases

Nanotechnology is a growing science that has applications in various areas of medicine. The composition of nanocarriers for drug delivery is critical to guarantee high therapeutic performance when targeting specific host sites. Applications of nanotechnology are prevalent in the diagnosis and treatment of infectious and inflammatory diseases. This review summarizes recent advancements in the application of nanotechnology to the therapy of infectious and inflammatory diseases. The major focus is on the design and fabrication of various nanomaterials, characteristics and physicochemical properties of drug-loaded nanocarriers, and the use of these nanoscale drug delivery systems in treating infectious and inflammatory diseases, such as AIDS, hepatitis, tuberculosis, melanoma, and representative inflammatory diseases. Clinical trials and future perspective of the use of nanocarriers are also discussed in detail. We hope that such a review will be valuable to researchers who are exploring nanoscale drug delivery systems for the treatment of specific infectious and inflammatory diseases.