The effect of treating infected skin grafts with Acticoat™ on immune cells

Treatment of infection and inflammation associated with COVID-19, multi-drug resistant pneumonia and fungal sinusitis by nebulizing a nanosilver solution

Solutions containing Ag⁰ nanoclusters, Ag⁺¹, and higher oxidation state silver, generated from nanocrystalline silver dressings, were anti-inflammatory against porcine skin inflammation. The dressings have clinically-demonstrated broad-spectrum antimicrobial activity, suggesting application of nanosilver solutions in treating pulmonary infection. Nanosilver solutions were tested for antimicrobial efficacy; against HSV-1 and SARS-CoV-2; and nebulized in rats with acute pneumonia. Patients with pneumonia (ventilated), fungal sinusitis, burns plus COVID-19, and two non-hospitalized patients with COVID-19 received nebulized nanosilver solution. Nanosilver solutions demonstrated pH-dependent antimicrobial efficacy; reduced infection and inflammation without evidence of lung toxicity in the rat model; and inactivated HSV-1 and SARS-CoV-2. Pneumonia patients had rapidly reduced pulmonary symptoms, recovering pre-illness respiratory function. Fungal sinusitis-related inflammation decreased immediately with infection clearance within 21 days. Non-hospitalized patients with COVID-19 experienced rapid symptom remission. Nanosilver solutions, due to anti-inflammatory, antiviral, and antimicrobial activity, may be effective for treating respiratory inflammation and infections caused by viruses and/or microbes.

Anticandidal Potential of Two Cyanobacteria-Synthesized Silver Nanoparticles: Effects on Growth, Cell Morphology, and Key Virulence Attributes of Candida albicans

Candida albicans is an opportunistic human fungal pathogen responsible for 90-100% of mucosal and nosocomial infections worldwide. The emergence of drug-resistant strains has resulted in adverse consequences for human health, including numerous deaths. Consequently, there is an urgent need to identify and develop new antimicrobial drugs to counter these effects. Antimicrobial nanoagents have shown potent inhibitory activity against a number of pathogens through targeting their defense systems, such as biofilm formation. Here, we investigated the anticandidal activity of silver nanoparticles biosynthesized by the cyanobacterial strains Desertifilum sp. IPPAS B-1220 and Nostoc Bahar_M (D-SNPs and N-SNPs, respectively), along with that of silver nitrate (AgNO3), and examined the mechanisms underlying their lethal effects. For this, we performed agar well diffusion and enzyme activity assays (lactate dehydrogenase, adenosine triphosphatase, glutathione peroxidase, and catalase) and undertook morphological examinations using transmission electron microscopy. The effects of the three treatments on Hwp1 and CDR1 gene expression and protein patterns were assessed using qRT-PCR and SDS-PAGE assays, respectively. All of the three treatments inhibited C. albicans growth; disrupted membrane integrity, metabolic function, and antioxidant activity; induced ultrastructural changes in the cell envelope; and disrupted cytoplasmic and nuclear contents. Of the three agents, D-SNPs showed the greatest biocidal activity against C. albicans. Additionally, the D-SNP treatment significantly reduced the gene expression of Hwp1 and CDR1, suggestive of negative effects on biofilm formation ability and resistance potential of C. albicans, and promoted protein degradation. The mechanism involved in the biocidal effects of both D-SNPs and N-SNPs against C. albicans could be attributed to their ability to interfere with fungal cell structures and/or stimulate oxidative stress, enabling them to be used as a robust antimycotic agent.

Lethal Mechanisms of Nostoc-Synthesized Silver Nanoparticles Against Different Pathogenic Bacteria

BACKGROUND

Increasing antibiotic resistance and the emergence of multidrug-resistant (MDR) pathogens have led to the need to develop new therapeutic agents to tackle microbial infections. Nano-antibiotics are a novel generation of nanomaterials with significant antimicrobial activities that target bacterial defense systems including biofilm formation, membrane permeability, and virulence activity.

PURPOSE

In addition to AgNO3, the current study aimed to explore for first time the antibacterial potential of silver nanoparticles synthesized by Nostoc sp. Bahar_M (N-SNPs) and their killing mechanisms against Streptococcus mutans, methicillin-resistant Staphylococcus aureus, Escherichia coli, and Salmonella typhimurium.

METHODS

Potential mechanisms of action of both silver species against bacteria were systematically explored using agar well diffusion, enzyme (lactate dehydrogenase (LDH) and ATPase) and antioxidant (glutathione peroxidase and catalase)   assays, and morphological examinations. qRT-PCR and SDS-PAGE were employed to investigate the effect of both treatments on mfD, flu, and hly gene expression and protein patterns, respectively.

RESULTS

N-SNPs exhibited greater biocidal activity than AgNO3 against the four tested bacteria. E. coli treated with N-SNPs showed significant surges in LDH levels, imbalances in other antioxidant and enzyme activities, and marked morphological changes, including cell membrane disruption and cytoplasmic dissolution. N-SNPs caused more significant upregulation of mfD expression and downregulation of both flu and hly expression and increased protein denaturation compared with AgNO3.

CONCLUSION

N-SNPs exhibited significant inhibitory potential against E. coli by direct interfering with bacterial cellular structures and/or enhancing oxidative stress, indicating their potential for use as an alternative antimicrobial agent. However, the potential of N-SNPs to be usable and biocompatible antibacterial drug will evaluate by their toxicity against normal cells.

Oxidative Stress and Apoptotic Responses Elicited by Nostoc-Synthesized Silver Nanoparticles against Different Cancer Cell Lines

Green nanoparticles represent a revolution in bionanotechnology, providing opportunities to fight life-threatening diseases, such as cancer, with less risk to the environment and to human health. Here, for the first time, we systematically investigated the anticancer activity and possible mechanism of novel silver nanoparticles (N-SNPs) synthesized by Nostoc Bahar M against the MCF-7 breast cancer cells, HCT-116 colorectal adenocarcinoma cells, and HepG2 liver cancer cells, using cell viability assays, morphological characterization with inverted light and transmission electron microscopy, antioxidants and enzymes (glutathione peroxidase (GPx), glutathione (GSH), adenosine triphosphatase (ATPase), and lactate dehydrogenase (LDH)), and western blotting (protein kinase B (Akt), phosphorylated-Akt (p-Akt), mammalian target of rapamycin (mTOR), B-cell lymphoma 2 (Bcl-2), tumor suppressor (p53), and caspase 3). N-SNPs decreased the viability of MCF-7, HCT-116, and HepG2 cells, with half-maximal inhibitory concentrations of 54, 56, and 80 µg/mL, respectively. They also significantly increased LDH leakage, enhanced oxidative stress via effects on antioxidative markers, and caused metabolic stress by significantly decreasing ATPase levels. N-SNPs caused extensive ultrastructural alterations in cell and nuclear structures, as well as in various organelles. Furthermore, N-SNPs triggered apoptosis via the activation of caspase 3 and p53, and suppressed the mTOR signaling pathway via downregulating apoptosis-evading proteins in MCF-7, HCT-116, and HepG2 cells. Ultrastructural analysis, together with biochemical and molecular analyses, revealed that N-SNPs enhanced apoptosis via the induction of oxidative stress and/or through direct interactions with cellular structures in all tested cells. The cytotoxicity of Nostoc-mediated SNPs represents a new strategy for cancer treatment via targeting various cell death pathways. However, the potential of N-SNPs to be usable and biocompatible anticancer drug will depend on their toxicity against normal cells.

Crystalline assembly of gold nanoclusters for mitochondria targeted cancer theranostics

Herein, we report the formation of a crystalline assembly of gold (Au) nanoclusters for cancer theranostics via active targeting of mitochondria.

Anti-cancerous effect of albumin coated silver nanoparticles on MDA-MB 231 human breast cancer cell line

With the aim of making specific targeting of silver nanoparticles as a drug for tumor cells and developing new anticancer agents, a novel nano-composite was developed. Albumin coated silver nanoparticles (ASNPs) were synthesized, and their anti-cancerous effects were evaluated against MDA-MB 231, a human breast cancer cell line. The synthesized ASNPs were characterized by spectroscopic methods. The morphological changes of the cells were observed by inverted, florescent microscopy and also by DNA ladder pattern on gel electrophoresis; the results revealed that the cell death process occurred through the apoptosis mechanism. It was found that ASNPs with a size of 90 nm and negatively charged with a zeta-potential of about −20 mV could be specifically taken up by tumor cells. The LD₅₀ of ASNPs against MDA-MB 231 (5 μM), was found to be 30 times higher than that for white normal blood cells (152 μM). The characteristics of the synthesized ASNPs included; intact structure of coated albumin, higher cytotoxicity against cancer cells than over normal cells, and cell death based on apoptosis and reduction of gland tumor sizes in mice. This work indicates that ASNPs could be a good candidate for chemotherapeutic drug.

Progress in rigid polysaccharide-based nanocomposites with therapeutic functions

Nanocomposites engineered by incorporating versatile nanoparticles into different bioactive β-glucan matrices display effective therapeutic functions.

Improving cytotoxicity against cancer cells by chemo-photodynamic combined modalities using silver-graphene quantum dots nanocomposites

The combination of chemotherapy and photodynamic therapy has emerged as a promising strategy for cancer therapy due to its synergistic effects. In this work, PEGylated silver nanoparticles decorated with graphene quantum dots (Ag-GQDs) were tested as a platform to deliver a chemotherapy drug and a photosensitizer, simultaneously, in chemo-photodynamic therapy against HeLa and DU145 cancer cells in vitro. Ag-GQDs have displayed high efficiency in delivering doxorubicin as a model chemotherapy drug to both cancer cells. The Ag-GQDs exhibited a strong antitumor activity by inducing apoptosis in cancer cells without affecting the viability of normal cells. Moreover, the Ag-GQDs exhibited a cytotoxic effect due to the generation of the reactive singlet oxygen upon 425 nm irradiation, indicating their applicability in photodynamic therapy. In comparison with chemo or photodynamic treatment alone, the combined treatment of Ag-GQDs conjugated with doxorubicin under irradiation with a 425 nm lamp significantly increased the death in DU145 and HeLa. This study suggests Ag-GQDs as a multifunctional and efficient therapeutic system for chemo-photodynamic modalities in cancer therapy.

Hybrid wound dressings with controlled release of antibiotics: Structure-release profile effects and in vivo study in a guinea pig burn model

Over the last decades, wound dressings have evolved from a crude traditional gauze dressing to tissue-engineered scaffolds. Many types of wound dressing formats are commercially available or have been investigated. We developed and studied hybrid bilayer wound dressings which combine a drug-loaded porous poly(dl-lactic-co-glycolic acid) top layer with a spongy collagen sublayer. Such a structure is very promising because it combines the advantageous properties of both layers. The antibiotic drug gentamicin was incorporated into the top layer for preventing and/or defeating infections. In this study, we examined the effect of the top layer's structure on the gentamicin release profile and on the resulting in vivo wound healing. The latter was tested on a guinea pig burn model, compared to the neutral non-adherent dressing material Melolin® (Smith & Nephew) and Aquacel® Ag (ConvaTec). The release kinetics of gentamicin from the various studied formulations exhibited burst release values between 8% and 38%, followed by a drug elution rate that decreased with time and lasted for at least 7 weeks. The hybrid dressing, with relatively slow gentamicin release, enabled the highest degree of wound healing (28%), which is at least double that obtained by the other dressing formats (8-12%). It resulted in the lowest degree of wound contraction and a relatively low amount of inflammatory cells compared to the controls. This dressing was found to be superior to hybrid wound dressings with fast gentamicin release and to the neat hybrid dressing without drug release. Since this dressing exhibited promising results and does not require frequent bandage changes, it offers a potentially valuable concept for treating large infected burns.

Dual-functional carbon dots–silver@zinc oxide nanocomposite: in vitro evaluation of cellular uptake and induction of apoptosis

We report here the devleopment of novel CDs decorated on a silver–zinc oxide (CD–Ag@ZnO) nanocomposite (NC) consisting of highly fluorescent CDs and Ag@ZnO.

Tumor-targeted folate-decorated albumin-stabilised silver nanoparticles induce apoptosis at low concentration in human breast cancer cells

The current study exploits the folate-mediated delivery of bovine serum albumin (BSA) stabilized Ag NPs and thereby overcomes various drawbacks associated with non-specific targeting.

Highly porous drug-eluting structures: from wound dressings to stents and scaffolds for tissue regeneration

For many biomedical applications, there is need for porous implant materials. The current article focuses on a method for preparation of drug-eluting porous structures for various biomedical applications, based on freeze drying of inverted emulsions. This fabrication process enables the incorporation of any drug, to obtain an "active implant" that releases drugs to the surrounding tissue in a controlled desired manner. Examples for porous implants based on this technique are antibiotic-eluting mesh/matrix structures used for wound healing applications, antiproliferative drug-eluting composite fibers for stent applications and local cancer treatment, and protein-eluting films for tissue regeneration applications. In the current review we focus on these systems. We show that the release profiles of both types of drugs, water-soluble and water-insoluble, are affected by the emulsion's formulation parameters. The former's release profile is affected mainly through the emulsion stability and the resulting porous microstructure, whereas the latter's release mechanism occurs via water uptake and degradation of the host polymer. Hence, appropriate selection of the formulation parameters enables to obtain desired controllable release profile of any bioactive agent, water-soluble or water-insoluble, and also fit its physical properties to the application.

Novel biodegradable composite wound dressings with controlled release of antibiotics: results in a guinea pig burn model

Approximately 70% of all people with severe burns die from related infections despite advances in treatment regimens and the best efforts of nurses and doctors. Silver ion-eluting wound dressings are available for overcoming this problem. However, there are reports of deleterious effects of such dressings due to cellular toxicity that delays the healing process, and the dressing changes needed 1-2 times a day are uncomfortable for the patient and time consuming for the stuff. An alternative concept in wound dressing design that combines the advantages of occlusive dressings with biodegradability and intrinsic topical antibiotic treatment is described herewith. The new composite structure presented in this article is based on a polyglyconate mesh and a porous poly-(dl-lactic-co-glycolic acid) matrix loaded with gentamicin developed to provide controlled release of antibiotics for three weeks. In vivo evaluation of the dressing material in contaminated deep second degree burn wounds in guinea pigs (n=20) demonstrated its ability to accelerate epithelialization by 40% compared to an unloaded format of the material and a conventional dressing material. Wound contraction was reduced significantly, and a better quality scar tissue was formed. The current dressing material exhibits promising results, does not require frequent bandage changes, and offers a potentially valuable and economic approach to treating the life-threatening complication of burn-related infections.

Induction of apoptosis in cancer cells at low silver nanoparticle concentrations using chitosan nanocarrier

We report the development of a chitosan nanocarrier (NC)-based delivery of silver nanoparticles (Ag NPs) to mammalian cells for induction of apoptosis at very low concentrations of the NPs. The cytotoxic efficacy of the Ag NP-nanocarrier (Ag-CS NC) system in human colon cancer cells (HT 29) was examined by morphological analyses and biochemical assays. Cell viability assay demonstrated that the concentration of Ag NPs required to reduce the viability of HT 29 cells by 50% was 0.33 μg mL(-1), much less than in previously reported data. The efficient induction of apoptosis by Ag-CS NCs was confirmed by flow cytometry. Additionally, the characteristic nuclear and morphological changes during apoptotic cell death were investigated by fluorescence and scanning electron microscopy (SEM), respectively. The involvement of mitochondrial pathway of cell death in the Ag-CS NCs induced apoptosis was evident from the depolarization of mitochondrial membrane potential (ΔΨ(m)). Real time quantitative RT-PCR analysis demonstrated the up-regulation of caspase 3 expression which was further reflected in the formation of oligo-nucleosomal DNA "ladders" in Ag-CS NCs treated cells, indicating the important role of caspases in the present apoptotic process. The increased production of intracellular ROS due to Ag-CS NCs treatment indicated that the oxidative stress could augment the induction of apoptosis in HT 29 cells in addition to classical caspase signaling pathway. The use of significantly low concentration of Ag NPs impregnated in chitosan nanocarrier is a much superior approach in comparison to the use of free Ag NPs in cancer therapy.

Use of Acticoat dressings in burns: what is the evidence?

The virtues of silver as an antimicrobial agent have been known for some time. Various silver containing dressings are currently used for the treatment of wounds. Introduced in the late 1990s, Acticoat is a nanocrystalline silver dressing developed to overcome some shortcomings of the older dressings by providing sustained release of silver up to 7 days. We aim to determine the level of evidence available in the literature in view of recent increased usage of Acticoat. A Medline search was conducted to identify articles evaluating the use of Acticoat in burn wounds. A level of evidence adapted from the Oxford Centre for Evidence-Based-Medicine was assigned to each of these articles. Only one study was considered to be LOE 1, which is a multicentre randomised controlled trial comparing Acticoat against Silver Sulfadiazine. One further randomised control trial was downgraded to LOE 2 due to a wide confidence interval. Twenty studies (66%) were LOE 5 of which 6 were case reports and 14 were in vitro/animal studies. The available LOE 1 study demonstrates that Acticoat has better antimicrobial activity compared to another available silver dressing. Other studies suggest Acticoat has fewer adverse effects and reduces healing times. Its ease of application and low frequency of change makes it an ideal dressing in burn wounds. More well designed and properly reported randomised controlled trials are essential for informed clinical decision-making.