Active silver nanoparticles for wound healing

Near-infrared-emitting nanoparticles activate collagen synthesis via TGFβ signaling

Research efforts towards developing near-infrared (NIR) therapeutics to activate the proliferation of human keratinocytes and collagen synthesis in the skin microenvironment have been minimal, and the subject has not been fully explored. Herein, we describe the novel synthesis Ag2S nanoparticles (NPs) by using a sonochemical method and reveal the effects of NIR irradiation on the enhancement of the production of collagen through NIR-emitting Ag2S NPs. We also synthesized Li-doped Ag2S NPs that exhibited significantly increased emission intensity because of their enhanced absorption ability in the UV-NIR region. Both Ag2S and Li-doped Ag2S NPs activated the proliferation of HaCaT (human keratinocyte) and HDF (human dermal fibroblast) cells with no effect on cell morphology. While Ag2S NPs upregulated TIMP1 by only twofold in HaCaT cells and TGF-β1 by only fourfold in HDF cells, Li-doped Ag2S NPs upregulated TGF-β1 by tenfold, TIMP1 by 26-fold, and COL1A1 by 18-fold in HaCaT cells and upregulated TGF-β1 by fivefold and COL1A1 by fourfold in HDF cells. Furthermore, Ag2S NPs activated TGF-β1 signaling by increasing the phosphorylation of Smad2 and Smad3. The degree of activation was notably higher in cells treated with Li-doped Ag2S NPs, mainly caused by the higher PL intensity from Li-doped Ag2S NPs. Ag2S NPs NIR activates cell proliferation and collagen synthesis in skin keratinocytes and HDF cells, which can be applied to clinical light therapy and the development of anti-wrinkle agents for cosmetics.

Biogenically Synthesized Polysaccharides-Capped Silver Nanoparticles: Immunomodulatory and Antibacterial Potentialities Against Resistant Pseudomonas aeruginosa

Bacterial infections are the key cause of death in patients suffering from burns and diabetic wounds while the use of traditional antibiotics has been growing steadily. Thus, in the present study, we are trying to introduce a paradigm shift strategy to improve chronic wound healing of bacterial infection. To that end, we have biologically synthesized silver nanoparticles (AgNPs) using Arthrospira sp polysaccharides, and evaluated their antibacterial efficacy with their safety pattern. Scanning electron micrographs showed spherical AgNPs coated with algal polysaccharides with an approximate size of 9.7 nm. Treatment of Pseudomonas aeruginosa with the AgNPs (0.5–1 μg/mL) resulted in a significant disruption in P. aeruginosa outer membrane, reduction in biofilm formation, and a significant decrease of production of alginate and pyocyanin along with a concentration-dependent reduction in β-lactamase activity. In addition, at the in vivo level, AgNPs displayed substantial activity to control P. aeruginosa infections in rat skin wounds with significant reduction in in COX-2 enzyme in both rat skin homogenate and serum samples. Furthermore, AgNPs facilitated wound curative in the P. aeruginosa infected model by reducing the hemorrhagic areas number and the infiltrated inflammatory cells. Taken all together, these biogenic nanoparticles showed unique properties in controlling bacterial wound infections and improving the healing process of damaged tissues via its direct and indirect effects.

A human skin equivalent burn model to study the effect of a nanocrystalline silver dressing on wound healing

In this study, a deep burn wound model was established using a 3D human skin equivalent (HSE) model and this was compared to native skin. HSEs were constructed from dermis derived from abdominoplasty/breast surgery and this dermal template was seeded with primary keratinocytes and fibroblasts. The HSE model was structurally similar to native skin with a stratified and differentiated epidermis. A contact burn (60 °C, 80 °C, 90 °C) was applied with a modified soldering iron and wounds were observed at day 1 and 7 after burn. The HSEs demonstrated re-growth with keratinocyte proliferation and formation of a neo-epidermis after burn injury, whereas the ex vivo native skin did not. To assess the suitability of the 3D HSE model for penetration and toxicity studies, a nanocrystalline silver dressing was applied to the model for 7 days, with and without burn injury. The effect of silver on skin re-growth and its penetration and subcellular localization was assessed in HSEs histologically and with laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS). The silver treatment delayed or reduced skin re-growth, and silver particles were detected on the top of the epidermis, and within the papillary dermis. This novel in vitro 3D multicellular deep burn wound model is effective for studying the pathology and treatment of burn wound injury and is suitable for penetration and toxicity studies of wound healing treatments.

Silver nanoparticles: Synthesis, medical applications and biosafety

Silver nanoparticles (AgNPs) have been one of the most attractive nanomaterials in biomedicine due to their unique physicochemical properties. In this paper, we review the state-of-the-art advances of AgNPs in the synthesis methods, medical applications and biosafety of AgNPs. The synthesis methods of AgNPs include physical, chemical and biological routes. AgNPs are mainly used for antimicrobial and anticancer therapy, and also applied in the promotion of wound repair and bone healing, or as the vaccine adjuvant, anti-diabetic agent and biosensors. This review also summarizes the biological action mechanisms of AgNPs, which mainly involve the release of silver ions (Ag+), generation of reactive oxygen species (ROS), destruction of membrane structure. Despite these therapeutic benefits, their biological safety problems such as potential toxicity on cells, tissue, and organs should be paid enough attention. Besides, we briefly introduce a new type of Ag particles smaller than AgNPs, silver Ångstrom (Å, 1 Å = 0.1 nm) particles (AgÅPs), which exhibit better biological activity and lower toxicity compared with AgNPs. Finally, we conclude the current challenges and point out the future development direction of AgNPs.

Photosensitized reactive chlorine species-mediated therapeutic destruction of drug-resistant bacteria using plasmonic core-shell Ag@AgCl nanocubes as an external nanomedicine

Due to the rapid growth of drug-resistant bacterial infections, there is an urgent need to develop innovative antimicrobial strategies to conquer the bacterial antibiotic resistance problems. Although a few nanomaterial-based antimicrobial strategies have been developed, the sensitized formation of cytotoxic reactive chlorine species (RCS), including chlorine gas and chlorine free radicals, by photo-activatable plasmonic nanoparticles for evading drug-resistant bacterial infections has not yet been reported. To address this challenge, herein, we report the synthesis of an unprecedented plasmonic core-shell Ag@AgCl nanocrystal through an in situ oxidation route for the photo-induced generation of highly cytotoxic RCS. We present the detailed in vitro and in vivo investigations of visible light activated Ag@AgCl nanostructure-mediated evasion of drug-resistant bacteria. In particular, the in vivo results demonstrate the complete reepithelialization of the methicillin-resistant Staphylococcus aureus (MRSA) infected wounds on skin upon phototherapeutic treatment mediated Ag@AgCl NCs. To the best of our knowledge, this is the first unique example of using Ag@AgCl NCs as an external nanomedicine for photo-induced generation of RCS to mediate effective killing of both Gram-positive and Gram-negative drug resistance bacteria and healing of the subcutaneous abscesses in an in vivo mouse model.

Development of Silver Nanoparticles/Gelatin Thermoresponsive Nanocomposites: Characterization and Antimicrobial Activity

BACKGROUND

Skin and soft tissue infections involve microbial invasion of the skin and underlying soft tissues. To overcome this problem, nanocomposites were obtained using gelatin as a biopolymer scaffold and silver nanoparticles as a wide spectrum antimicrobial agent. Water and glycerol have been used as solvents for the gelatin hydrogel synthesis. This mixture led to a stable and homogeneous biomaterial with improved mechanical properties.

METHODS

Silver nanoparticles were characterized using SEM, EDS and TEM. Moreover, the AgNp/gelatin nanocomposite obtained using these nanoparticles was characterized using SEM and FTIR. Moreover, mechanical and swelling properties were studied.

RESULTS

The storage modulus was 3000 Pa for gelatin hydrogels and reached 5800 Pa for AgNp/gelatin nanocomposite. Silver nanoparticles have been studied as an alternative to antibiotics. Importantly, the rate of silver release was modulated as a function of the temperature of the nanocomposite. Thus, the silver release from the nanocomposites at 24 °C and 38 °C was analyzed by atomic absorption spectroscopy. The silver release reached 25% after 24 h at 24 °C, while a 75% release was achieved at 38°C in the same period, showing the material thermoresponsive behavior. AgNp/gelatin nanocomposite showed a deleterious effect over 99.99% of Pseudomonas aeruginosa and Staphylococcus aureus, leading to a material with antimicrobial properties.

CONCLUSION

AgNp/gelatin nanocomposite with improved mechanical properties and silver nanoparticles as a source of silver ions has been synthesized. The properties of the nanocomposite with controlled silver delivery result in a more efficient topical pharmaceutical form for wound healing applications.

Targeting Tunable Physical Properties of Materials for Chronic Wound Care

Chronic wounds caused by infections, diabetes, and radiation exposures are becoming a worldwide growing medical burden. Recent progress highlighted the physical signals determining stem cell fates and bacterial resistance, which holds potential to achieve a better wound regeneration in situ. Nanoparticles (NPs) would benefit chronic wound healing. However, the cytotoxicity of the silver NPs (AgNPs) has aroused many concerns. This review targets the tunable physical properties (i.e., mechanical-, structural-, and size-related properties) of either dermal matrixes or wound dressings for chronic wound care. Firstly, we discuss the recent discoveries about the mechanical- and structural-related regulation of stem cells. Specially, we point out the currently undocumented influence of tunable mechanical and structural properties on either the fate of each cell type or the whole wound healing process. Secondly, we highlight novel dermal matrixes based on either natural tropoelastin or synthetic elastin-like recombinamers (ELRs) for providing elastic recoil and resilience to the wounded dermis. Thirdly, we discuss the application of wound dressings in terms of size-related properties (i.e., metal NPs, lipid NPs, polymeric NPs). Moreover, we highlight the cytotoxicity of AgNPs and propose the size-, dose-, and time-dependent solutions for reducing their cytotoxicity in wound care. This review will hopefully inspire the advanced design strategies of either dermal matrixes or wound dressings and their potential therapeutic benefits for chronic wounds.

Recent Advances in Nanomaterial-Based Wound-Healing Therapeutics

Nanomaterial-based wound healing has tremendous potential for treating and preventing wound infections with its multiple benefits compared with traditional treatment approaches. In this regard, the physiochemical properties of nanomaterials enable researchers to conduct extensive studies on wound-healing applications. Nonetheless, issues concerning the use of nanomaterials in accelerating the efficacy of existing medical treatments remain unresolved. The present review highlights novel approaches focusing on the recent innovative strategies for wound healing and infection controls based on nanomaterials, including nanoparticles, nanocomposites, and scaffolds, which are elucidated in detail. In addition, the efficacy of nanomaterials as carriers for therapeutic agents associated with wound-healing applications has been addressed. Finally, nanomaterial-based scaffolds and their premise for future studies have been described. We believe that the in-depth analytical review, future insights, and potential challenges described herein will provide researchers an up-to-date reference on the use of nanomedicine and its innovative approaches that can enhance wound-healing applications.

Silver(i) complexes with different pyridine-4,5-dicarboxylate ligands as efficient agents for the control of cow mastitis associated pathogens

Infections of the cow udder leading to mastitis and lower milk quality are one of the biggest problems in the dairy industry worldwide. Unfortunately, therapeutic options for the treatment of cow mastitis are limited as a consequence of the development of pathogens that are resistant to conventionally used antibiotics. In the search for agents that will be active against cow mastitis associated pathogens, in the present study, five new silver(i) complexes with different chelating pyridine-4,5-dicarboxylate types of ligands, [Ag(NO₃)(py-2py)]_n (1), [Ag(NO₃)(py-2metz)]_n (2), [Ag(CH₃CN)(py-2py)]BF₄ (3), [Ag(py-2tz)₂]BF₄ (4) and [Ag(py-2metz)₂]BF₄ (5), py-2py is dimethyl 2,2'-bipyridine-4,5-dicarboxylate, py-2metz is dimethyl 2-(4-methylthiazol-2-yl)pyridine-4,5-dicarboxylate and py-2tz is dimethyl 2-(thiazol-2-yl)pyridine-4,5-dicarboxylate, were synthesized, structurally characterized and assessed for in vitro antimicrobial activity using both standard bioassay and clinical isolates from a contaminated milk sample obtained from a cow with mastitis. These complexes showed remarkable activity against the standard panel of microorganisms and a selection of clinical isolates from the milk of the cow diagnosed with mastitis. With the aim of determining the therapeutic potential of silver(i) complexes, their toxicity in vivo against the model organism, Caenorhabditis elegans (C. elegans), was investigated. The complexes that had the best therapeutic profile, 2 and 5, induced bacterial membrane depolarization and the production of reactive oxygen species (ROS) in Candida albicans cells and inhibited the hyphae as well as the biofilm formation. Taken together, the presented data suggest that the silver(i) complexes with pyridine ligands could be considered for the treatment of microbial pathogens, which are causative agents of cow mastitis.

Nanoformulation of Biogenic Cefotaxime-Conjugated-Silver Nanoparticles for Enhanced Antibacterial Efficacy Against Multidrug-Resistant Bacteria and Anticancer Studies

OBJECTIVES

Due to the expanded bacterial genetic tolerance to antibiotics through different mechanisms, infectious diseases of MDR bacteria are difficult for treatment. Consequently, we synthesized drug conjugated nanoparticles to dissolve this problem. Moreover, the present study aims to display the cell death status treated with cefotaxime-CS-AgNPs and also, apoptosis pathways of human RPE-1 normal cells and human MCF-7 breast cancer cells.

METHODS

Here, we demonstrate the possibility to synthesize AgNPs and conjugate them with cefotaxime to survey the probability of cefotaxime-CS-AgNPs as an antimicrobial agent against cefotaxime-resistant strains E. coli and MRSA.

RESULTS

TEM showed the size of AgNPs, CS-AgNPs and cefotaxime-CS-AgNPs ranged from 7.42 to 18.3 nm, 8.05-23.89 nm and 8.48-25.3 nm, respectively, with a spherical shape. The cefotaxime-CS-AgNPs enhanced the high antimicrobial properties compared to AgNPs or pure antibiotic. The MIC of Cefotaxime-CS-AgNPs ranged from 3 µg/mL to 8 µg/mL against tested E. coli and MRSA bacteria. Consequently, the highest reduction in the MIC of cefotaxime-CS-AgNPs was noted against tested strains ranging from 22% to 96%. Comparing cefotaime-CS-AgNPs to AgNPs we showed that cefotaime-CS-AgNPs have no cytotoxic effect on normal cells at even 12 µg/mL for 24 hrs. The IC50 for the AgNPs and cefotaxime-CS-AgNPs was 12 µg/mL for human RPE-1 normal cells and human MCF-7 breast cancer cell lines. The pro-apoptotic genes p53, p21, and Bax of cancer cell lines significantly upregulated followed by downregulated by anti-apoptotic gene Bcl-2 after 48 hrs at 24 µg/mL, and this concentration represents the most effective dose.

CONCLUSION

Results enhanced the conjugating utility in old unresponsive cefotaxime to AgNPs to restore its efficiency against previous strains and demonstrated potential therapeutic applications of cefotaxime-CS-AgNPs. Moreover, this research gives remarkable insights for designing nanoscale delivery and curative systems that have a pronounced cytotoxic activity on cancer cells and are safe to normal cells.

Therapeutic advances in wound healing

Wound healing is a complex physiological process that occurs in the human body involving the sequential activation of multiple cell types and signaling pathways in a coordinated manner. Chronic wounds and burns clearly decrease quality of life of the patients since they are associated with an increase in physical pain and socio-economical complications. Furthermore, incidence and prevalence of chronic wounds (unlike burns) have been increasing mainly due to population aging resulting in increased costs for national health systems. Thus, the development of new and more cost-effective technologies/therapies is not only of huge interest but also necessary to improve the long-term sustainability of national health systems. This review covers the current knowledge on recent technologies/therapies for skin regeneration, such as: wound dressings; skin substitutes; exogenous growth factor based therapy and systemic therapy; external tissue expanders; negative pressure; oxygen; shock wave, and photobiomodulation wound therapies. Associated benefits and risks as well as the clinical use and availability are all addressed for each therapy. Moreover, future trends in wound care including novel formulations using metallic nanoparticles and topical insulin are herein presented. These novel formulations have shown to be promising therapeutic options in the near future that may change the wound care paradigm.

Study of Antibacterial Properties of Ziziphus mauritiana based Green Synthesized Silver Nanoparticles against Various Bacterial Strains

Due to their low cost and environmentally friendly nature, plant extracts based methods have gained significant popularity among researchers for the synthesis of metallic nanoparticles. Herein, green synthesis of silver nanoparticles was performed using the aqueous solution of Ziziphus mauritiana leaves extract (ZM-LE) as a bio-reducing agent. The as-obtained silver nanoparticles were characterized by using UV-Vis spectroscopy, XRD (X-ray diffraction), TEM (transmission electron microscopy), and FT-IR (Fourier-transform infrared spectroscopy). In addition, the effects of the concentrations of the leaves extract, silver nitrate, and the temperature on the preparation of nanoparticles were also investigated. In order to determine the nature of secondary metabolites present in leaves extract, a preliminary investigation of phytoconstituents was carried out using different methods including Folin-Ciocalteu and AlCl3 methods. The results have indicated the presence of a considerable amount of phenolic and flavonoid contents in the leaves extract, which are believed to be responsible for the reduction of silver ions and stabilization of resulting nanoparticles. Indeed, the FT-IR spectrum of silver nanoparticles also confirmed the presence of residual phytomolecules of leaves extract as stabilizing ligands on the surface of nanoparticles. The antibacterial properties of as-obtained silver nanoparticles were tested against various bacterial strains including Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis. The nanoparticles strongly inhibited the growth of S. aureus with a minimum inhibitory concentration (MIC) of 2.5 μg/ml and moderately inhibited the growth of E. coli with a MIC of 5 μg/ml.

Efficacy and safety of nano-silver dressings combined with recombinant human epidermal growth factor for deep second-degree burns: A meta-analysis

OBJECTIVE

The purpose of this meta-analysis was to assess the efficacy and safety of nano-silver dressing combined with recombinant human epidermal growth factor for deep second-degree burns.

METHODS

PubMed, Web of Science, EMBASE, Cochrane Library and other databases were searched to identify relevant randomised controlled trials.

RESULTS

Twelve studies that assessed nano-silver dressing combined with recombinant human epidermal growth factor were identified. Nano-silver dressing combined with recombinant human epidermal growth factor for deep second-degree burns could significantly reduce the duration of wound healing (mean difference -5.68, 95% CI -7.38 - -3.99, P<0.00001), the wound healing rate (risk ratio [RR] 0.34, 95% CI 0.23-0.48, P<0.00001), the rate of scar hyperplasia (RR 0.67, 95% CI 0.54-0.84, P=0.0004), the wound bacterial positive rate (RR 0.50, 95% CI 0.28-0.89, P=0.02), and the adverse reactions rate (RR 0.31, 95% CI 0.16-0.58, P=0.0003).

CONCLUSION

This comprehensive meta-analysis of the available evidence suggest that the use of nano-silver dressing combined with recombinant human epidermal growth factor results in shorter duration of wound healing, reduced wound bacterial positive rates and adverse reactions rate, and improved wound healing rates.

Gold-silver nanoshells promote wound healing from drug-resistant bacteria infection and enable monitoring via surface-enhanced Raman scattering imaging

Chronic infections, caused by multidrug-resistant (MDR) bacteria, constitute a serious problem yet often underappreciated in clinical practice. The in situ monitoring of the bacteria-infected disease is also necessary to track and verify the therapeutic effect. Herein we present a facile approach to overcome the above challenges through a Raman tag 3,3'-diethylthiatricarbocyanine iodide (DTTC)-conjugated gold-silver nanoshells (AuAgNSs). With a strong responsive of the near-infrared laser due to surface plasmon resonance (SPR) from hybrid metallic nanoshell structure, AuAgNSs exhibits an efficient photothermal effect, and it simultaneously releases silver ions during laser irradiation to bacterial eradicate. Herein, two MDR bacteria strain, methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum β-lactamase Escherichia coli, are chosen as models and studied both in vitro and in vivo. As a result, the AuAgNSs-DTTC substrates enable surface-enhanced Raman scattering imaging to provide a non-invasive and extremely high sensitive detection (down to 300 CFU mL^-1 for MRSA) and prolonged tracking (at least 8 days) of residual bacteria. In a chronic MRSA-infected wound mouse model, the AuAgNSs gel-mediated photothermal therapy/silver-release leads to a synergistic would healing with negligible toxicity or collateral damage to vital organs. These results suggest that AuAgNSs-DTTC is a promising anti-bacterial tool for clinical translation.

Spatiotemporal distribution and speciation of silver nanoparticles in the healing wound

First observation of AgNPs dynamics in the wounds of real patients through elemental imaging and speciation.

Current status and future outlook of nano-based systems for burn wound management

Wound healing process is a natural and intricate response of the body to its injuries and includes a well-orchestrated sequence of biochemical and cellular phenomena to restore the integrity of skin and injured tissues. Complex nature and associated complications of burn wounds lead to an incomplete and prolonged recovery of these types of wounds. Among different materials and systems which have been used in treating the wounds, nanotechnology driven therapeutic systems showed a great opportunity to improvement and enhancement of the healing process of different type of wounds. The aim of this study is to provide an overview of the recent studies about the various nanotechnology-based management of burn wounds and the future outlook of these systems in this area. Laboratory and animal models for assessing the efficacy of these systems in burn wound management also discussed.

The Use of Nanomedicine for Targeted Therapy against Bacterial Infections

The emergence of drug resistance combined with limited success in the discovery of newer and effective antimicrobial chemotherapeutics poses a significant challenge to human and animal health. Nanoparticles may be an approach for effective drug development and delivery against infections caused by multi-drug resistant bacteria. Here we discuss nanoparticles therapeutics and nano-drug delivery against bacterial infections. The therapeutic efficacy of numerous kinds of nanoparticles including nanoantibiotics conjugates, small molecules capped nanoparticles, polymers stabilized nanoparticles, and biomolecules functionalized nanoparticles has been discussed. Moreover, nanoparticles-based drug delivery systems against bacterial infections have been described. Furthermore, the fundamental limitation of biocompatibility and biosafety of nanoparticles is also conferred. Finally, we propose potential future strategies of nanomaterials as antibacterials.

Comparative safety analysis of bactericidal nano-colloids: Assessment of potential functional toxicity and radical scavenging action

Extensive utilization of silver nanoparticles (AgNP) has raised concerns of their safety profile upon interaction with biological system. In past decade, various nanoparticles (NPs) with excellent antimicrobial potential have been synthesized, a majority of which have struggled with the established toxicity in biological systems. The NPs safety is still a hot debate and various strategies are being adopted to overcome this giant limitation. This paper successfully reports comparative toxicity profiles of previously synthesized antimicrobial NPs in our lab and concludes the effectiveness of biologically synthesized NPs for its safe usage in biological systems. In this study, five of our previously synthesized NPs that showed excellent antimicrobial potential were compared for their in vivo toxicity and corresponding radical scavenging activities. Based on lowest morbidity, mortality, weight loss, toxicity and agglomeration profile, best NPs with highest antimicrobial potentials were screened out and used for further biomedical applications. The previously reported NPs used in this study included Aerva javanica synthesized nanoparticles (AjNPs), Heliotropium crispium synthesized nanoparticles (HcNPs), and violacein capped nanoparticles (VNPs), these showed least toxicity upon in vivo histological analysis. AjNPs among them showed maximum safety and efficacy profile and consistently showed least production of reactive oxygen species, least mortality and morbidity rate as compared to other groups. Present study establishes that all these biologically synthesized NPs and specifically AjNPs can be efficiently employed as antimicrobial agents as they have not exhibited toxic profile and have shown least accumulation into the organs such as liver spleen and kidney.

Effects and formulation of silver nanoscaffolds on cytotoxicity dependent ion release kinetics towards enhanced excision wound healing patterns in Wistar albino rats

Wound tissue regeneration and angiogenesis are dynamic processes that send physiological signals to the body. Thus, designing novel nanoscaffolds by understanding their surface modifications and toxicological response in a biological system with a potent anti-inflammatory response is a viable solution. In this respect, inspired by the surface chemistry, in the present work we focus on the chemical optimization of silver nanoscaffolds using surface cappings in order to understand their kinetic release behaviour in simulated wound fluids (SWF), to analyze their blood compatibility in human lymphocytes and erythrocytes and then embed them in a chitosan-agarose matrix (CAM) as a productive drug delivery system to evaluate in vivo excision wound tissue regeneration efficiency in Wistar rats. In this regard, polyvinyl alcohol capped silver nanocomposites (PVA-AgNPs) exhibit a dominant antibacterial efficacy with the sustained and controlled release of silver ions and percentage cell mortality and percentage hemolysis of only 10% and 16% compared with uncapped-AgNPs or silver bandaids (SBDs). Also, PVA-AgNP impregnated CAM (PVA-CAM) shows positive effects through their anti-inflammatory and angiogenic properties, with a nearly 95% healing effect within 9 days. The complete development of collagen and fibroblast constituents was also monitored in PVA-CAM by hematoxylin & eosin (H & E) and Masson trichrome (MT) staining. These results provide a clear insight into the development of a potent therapeutic formulation using CAM as a scaffold incorporated with surface functionalized PVA-AgNPs as a bioeffective and biocompatible polymer for the fabrication of efficacious silver wound dressing scaffolds in clinical practice.

Lock Stock and Barrel of Wound Healing

Any kind of injury may lead to wound formation. As per World Health Organization Report, "more than 5 million people die each year due to injuries. This accounts for 9% of the world's population death, nearly 1.7 times the number of fatalities that result from HIV/AIDS, tuberculosis and malaria combined. In addition, ten million people suffer from non-fatal injuries which require treatment". This scenario leads to increased health and economic burden worldwide. Rapid wound healing is exigent subject-field in the health care system. It is imperative to be updated on wound care strategies as impaired wound healing may lead to chronic, non-healing wounds and thus further contributes to the national burden. This article is a comprehensive review of wound care strategies. The first and second part of this review article focuses on the understanding of wound, its types and human body's healing mechanism. Wound healing is natural, highly coordinated process that starts on its own, immediately after the injury. However, individual health condition influences the healing process. Discussion of factors affecting wound healing has also been included. Next part includes the detailed review of diverse wound healing strategies that have already been developed for different types of wound. A detailed description of various polymers that may be used has been discussed. Amongst drug delivery systems, oligomers, dendrimers, films, gels, different nano-formulations, like nanocomposites, nanofibers, nanoemulsions and nanoparticles are discussed. Emphasis on bandages has been made in this article.

Silver nanoparticle-induced developmental inhibition of Drosophila melanogaster accompanies disruption of genetic material of larval neural stem cells and non-neuronal cells

A few studies had determined the effects of silver nanoparticles on the development of Drosophila melanogaster. However, none had addressed its genotoxic effects on specific larval cells of the fly in details. This study was conducted to determine the effects of silver nanoparticle on the development of D. melanogaster with simultaneous evaluation of its genotoxic potential on specific larval cell types that play important roles in immunological defenses as well as growth and development. Five male and five female flies were maintained in standard Drosophila melanogaster culture medium containing varying concentrations of silver nanoparticles, i.e., 25, 50, 100, 200, and 300 mg/l with control culture medium containing no nanoparticle. Total time needed for stage-specific development, population yield, and genotoxic effects on third instar larval polytene chromosomes, hemocytes, and neuroblasts was determined. Body pigmentation of pupae and young adults was examined visually. In comparison with control, silver nanoparticles dose dependently inhibited the metamororphosis and population yields of pupae and young adults of Drosophila melanogaster. Every concentration of the nanoparticles inhibited pupa to adult conversion, with huge reduction under the influence of nanoparticle concentration of 100 mg/ml and above. Developmental inhibition was accompanied by dose-dependent and significant structural aberrations of larval polytene chromosomes and deformities of hemocytes and neuroblasts. Pupae and young adults also exhibited gradual discoloration of body with the increase in exposure to nanoparticle concentration.

Colloidal Silver Induces Cytoskeleton Reorganization and E-Cadherin Recruitment at Cell-Cell Contacts in HaCaT Cells

Up until the first half of the 20th century, silver found significant employment in medical applications, particularly in the healing of open wounds, thanks to its antibacterial and antifungal properties. Wound repair is a complex and dynamic biological process regulated by several pathways that cooperate to restore tissue integrity and homeostasis. To facilitate healing, injuries need to be promptly treated. Recently, the interest in alternatives to antibiotics has been raised given the widespread phenomenon of antibiotic resistance. Among these alternatives, the use of silver appears to be a valid option, so a resurgence in its use has been recently observed. In particular, in contrast to ionic silver, colloidal silver, a suspension of metallic silver particles, shows antibacterial activity displaying less or no toxicity. However, the human health risks associated with exposure to silver nanoparticles (NP) appear to be conflicted, and some studies have suggested that it could be toxic in different cellular contexts. These potentially harmful effects of silver NP depend on various parameters including NP size, which commonly range from 1 to 100 nm. In this study, we analyzed the effect of a colloidal silver preparation composed of very small and homogeneous nanoparticles of 0.62 nm size, smaller than those previously tested. We found no adverse effect on the cell proliferation of HaCaT cells, even at high NP concentration. Time-lapse microscopy and indirect immunofluorescence experiments demonstrated that this preparation of colloidal silver strongly increased cell migration, re-modeled the cytoskeleton, and caused recruitment of E-cadherin at cell-cell junctions of human cultured keratinocytes.

Upshift of the d Band Center toward the Fermi Level for Promoting Silver Ion Release, Bacteria Inactivation, and Wound Healing of Alloy Silver Nanoparticles

Silver (Ag)-based nanoparticles (NPs) with a high potential of Ag⁺ release have been known to be capable of promoting bacteria inactivation and the wound healing process; however, keeping a steady flux of high levels of Ag⁺ in Ag-based NPs is still challenging. Herein, a novel strategy in terms of altering the intrinsic electronic structure of Ag NPs was attempted to facilitate Ag oxidation and boost the Ag⁺ flux, as results of improved antibacterial and wound healing performance of Ag NPs. Gold (Au), platinum (Pt), and palladium (Pd) were doped into Ag NPs to tune their d band centers to upshift toward the Fermi level, and the formed Pd-Ag alloy NPs showed the largest shift, followed by Pt-Ag and Au-Ag NPs, as determined by density function theory calculation and ultraviolet photoemission spectroscopy measurement. Further X-ray photoelectron spectroscopy analysis indicates that a larger upshift could induce less electron filling in the antibonding orbital and a higher Ag oxidation level, leading to the more remarkable Ag⁺ release as determined by inductively coupled plasma optical emission spectrometry. All these alloy Ag NPs could more efficiently inhibit bacterial growth and accelerate the wound healing process than pure Ag NPs, and their antibacterial activity and wound healing performance were progressively proportional to the upshift values of the d band center. Taken together, tuning the d band center to upshift toward the Fermi level becomes a feasible strategy for designing therapeutic Ag-based NPs with a promising antibacterial and wound healing performance.

Gelatin-stabilized composites of silver nanoparticles and curcumin: characterization, antibacterial and antioxidant study

This is a preliminary study of a material comprising gelatin (Gel), silver nanoparticles (AgNPs) and curcumin (Cur) aimed for wound-healing treatment. Gelatin was used to stabilize AgNPs and encapsulate curcumin to form a therapeutic composite (GelCurAg) for their strong bactericidal and antioxidant properties. GelCurAg formulations with different gelatin concentrations were characterized to attain information about their physiochemical properties and the loading efficiency of therapeutic agents. In vitro assessment of GelCurAg focused on antibacterial, antioxidant and cytotoxic aspects. The results suggested that Gel1CurAg (synthesized from 1% gelatin solution) could be utilized as potential therapeutic agents in treating infectious wound owing to its bactericidal and antioxidant effects and low toxicity for clinical uses.

Starch-mediated synthesis of mono- and bimetallic silver/gold nanoparticles as antimicrobial and anticancer agents

BACKGROUND AND AIM

Bimetallic silver/gold nanosystems are expected to significantly improve therapeutic efficacy compared to their monometallic counterparts by maintaining the general biocompatibility of gold nanoparticles (AuNPs) while, at the same time, decreasing the relatively high toxicity of silver nanoparticles (AgNPs) toward healthy human cells. Thus, the aim of this research was to establish a highly reproducible one-pot green synthesis of colloidal AuNPs and bimetallic Ag/Au alloy nanoparticles (NPs; Ag/AuNPs) using starch as reducing and capping agent.

METHODS

The optical properties, high reproducibility, stability and particle size distribution of the colloidal NPs were analyzed by ultraviolet (UV)-visible spectroscopy, dynamic light scattering (DLS) and ζ-potential. The presence of starch as capping agent was determined by Fourier transform infrared (FT-IR) spectroscopy. The structural properties were studied by X-ray diffraction (XRD). Transmission electron microscopy (TEM) imaging was done to determine the morphology and size of the nanostructures. The chemical composition of the nanomaterials was determined by energy-dispersive X-ray spectroscopy (EDS) and inductively coupled plasma mass spectrometry (ICP-MS) analysis. To further study the biomedical applications of the synthesized nanostructures, antibacterial studies against multidrug-resistant (MDR) Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA) were conducted. In addition, the NPs were added to the growth media of human dermal fibroblast (HDF) and human melanoma cells to show their cytocompatibility and cytotoxicity, respectively, over a 3-day experiment.

RESULTS

UV-visible spectroscopy confirmed the highly reproducible green synthesis of colloidal AuNPs and Ag/AuNPs. The NPs showed a face-centered cubic crystal structure and an icosahedral shape with mean particle sizes of 28.5 and 9.7 nm for AuNPs and Ag/AuNPs, respectively. The antibacterial studies of the NPs against antibiotic-resistant bacterial strains presented a dose-dependent antimicrobial behavior. Furthermore, the NPs showed cytocompat-ibility towards HDF, but a dose-dependent anticancer effect was found when human melanoma cells were grown in presence of different NP concentrations for 72 hours.

CONCLUSION

In this study, mono- and bimetallic NPs were synthesized for the first time using a highly reproducible, environmentally friendly, cost-effective and quick method and were successfully characterized and tested for several anti-infection and anticancer biomedical applications.

In Vivo Study of the Antibacterial Chitosan/Polyvinyl Alcohol Loaded with Silver Nanoparticle Hydrogel for Wound Healing Applications

Silver nanoparticles have attracted great interests widely in medicine due to its great characteristics of antibacterial activity. In this research, the antibacterial activity and biocompatibility of a topical gel synthesized from polyvinyl alcohol, chitosan, and silver nanoparticles were studied. Hydrogels with different concentrations of silver nanoparticles (15 ppm, 30 ppm, and 60 ppm) were evaluated to compare their antibacterial activity, nanoparticles’ sizes, and in vivo behaviors. The resulted silver nanoparticles in the hydrogel were characterized by TEM showing the nanoparticles’ sizes less than 22 nm. The in vitro results prove that the antibacterial effects of all of the samples are satisfied. However, the in vivo results demonstrate the significant difference among different hydrogels in wound healing, where hydrogel with 30 ppm shows the best healing rate.

Application of micellar electrokinetic chromatography for detection of silver nanoparticles released from wound dressing

The recent emergence of nanotechnology has provided a new therapeutic modality in case of silver nanoparticles. Dressings containing silver form the basis for the treatment of burns and wounds, either acute or chronic ones. The aim of the study was to examine silver release from the different wound dressings: commercially available (Atrauman Ag, Aquacel Ag) and experimental (FKDP-AgNPs) using MEKC. In order to characterize prepared keratin based wound dressing before and after its modification with AgNPs, a compositional analysis was conducted using energy dispersive X-ray spectroscopy. Nanosilver toxicity was evaluated with the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4 sulfophenyl)-2H-tetrazolium test. Silver release from wound dressings was assessed using MEKC. The best separation was observed for MEKC in 20 mM borate buffer at pH 9 with 20 mM SDS addition. In vitro studies showed silver at higher concentration than 10 ppm exerted a toxic effect on fibroblasts isolated from diabetic mice versus. NIH/3T3 and BJ cell lines (p < 0.05). We observed silver was released more gradually from experimental FKDP-AgNPs wound dressing, in compare to commercially available wound dressings. The fast and low-cost method utilizing MEKC can be used in clinical practice to detect silver release from the wound dressings.

Nanomaterials as potential and versatile platform for next generation tissue engineering applications

Tissue engineering (TE) is an emerging field where alternate/artificial tissues or organ substitutes are implanted to mimic the functionality of damaged or injured tissues. Earlier efforts were made to develop natural, synthetic, or semisynthetic materials for skin equivalents to treat burns or skin wounds. Nowadays, many more tissues like bone, cardiac, cartilage, heart, liver, cornea, blood vessels, and so forth are being engineered using 3-D biomaterial constructs or scaffolds that could deliver active molecules such as peptides or growth factors. Nanomaterials (NMs) due to their unique mechanical, electrical, and optical properties possess significant opportunities in TE applications. Traditional TE scaffolds were based on hydrolytically degradable macroporous materials, whereas current approaches emphasize on controlling cell behaviors and tissue formation by nano-scale topography that closely mimics the natural extracellular matrix. This review article gives a comprehensive outlook of different organ specific NMs which are being used for diversified TE applications. Varieties of NMs are known to serve as biological alternatives to repair or replace a portion or whole of the nonfunctional or damaged tissue. NMs may promote greater amounts of specific interactions stimulated at the cellular level, ultimately leading to more efficient new tissue formation. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2433-2449, 2019.

Bactericidal and Cytotoxic Properties of Silver Nanoparticles

Silver nanoparticles (AgNPs) can be synthesized from a variety of techniques including physical, chemical and biological routes. They have been widely used as nanomaterials for manufacturing cosmetic and healthcare products, antimicrobial textiles, wound dressings, antitumor drug carriers, etc. due to their excellent antimicrobial properties. Accordingly, AgNPs have gained access into our daily life, and the inevitable human exposure to these nanoparticles has raised concerns about their potential hazards to the environment, health, and safety in recent years. From in vitro cell cultivation tests, AgNPs have been reported to be toxic to several human cell lines including human bronchial epithelial cells, human umbilical vein endothelial cells, red blood cells, human peripheral blood mononuclear cells, immortal human keratinocytes, liver cells, etc. AgNPs induce a dose-, size- and time-dependent cytotoxicity, particularly for those with sizes ≤10 nm. Furthermore, AgNPs can cross the brain blood barrier of mice through the circulation system on the basis of in vivo animal tests. AgNPs tend to accumulate in mice organs such as liver, spleen, kidney and brain following intravenous, intraperitoneal, and intratracheal routes of administration. In this respect, AgNPs are considered a double-edged sword that can eliminate microorganisms but induce cytotoxicity in mammalian cells. This article provides a state-of-the-art review on the synthesis of AgNPs, and their applications in antimicrobial textile fabrics, food packaging films, and wound dressings. Particular attention is paid to the bactericidal activity and cytotoxic effect in mammalian cells.

Recent advances in inorganic nanomaterials for wound-healing applications

The emergence of inorganic nanoparticles has generated considerable expectation for solving various biomedical issues including wound healing and tissue regeneration. This review article highlights the role and recent advancements of inorganic nanoparticles for wound healing and tissue regeneration along with their advantages, clinical status, challenges and future directions.

Potential Biomolecules and Current Treatment Technologies for Diabetic Foot Ulcer: An Overview

BACKGROUND

Diabetic foot ulceration remains a major challenge and is one of the most expensive and leading causes of major and minor amputations among patients with diabetic foot ulcer. Hence the purpose of this review is to emphasize on potential molecular markers involved in diabetic foot ulcer physiology, the efficacy of different types of dressing materials, adjunct therapy and newer therapeutic approach like nanoparticles for the treatment of diabetic foot ulcer.

METHODS

We conducted a systematic literature review search by using Pubmed and other web searches. The quality evidence of diabetic foot ulcer biomolecules and treatments was collected, summarized and compared with other studies.

RESULTS

The present investigation suggested that impaired wound healing in diabetic patients is an influence of several factors. All the advanced therapies and foot ulcer dressing materials are not suitable for all types of diabetic foot ulcers, however more prospective follow ups and in vivo and in vitro studies are needed to draw certain conclusion. Several critical wound biomolecules have been identified and are in need to be investigated in diabetic foot ulcers. The application of biocompatible nanoparticles holds a promising approach for designing dressing materials for the treatment of diabetic foot ulcer.

CONCLUSION

Understanding the cellular and molecular events and identifying the appropriate treatment strategies for different foot ulcer grades will reduce recurrence of foot ulcer and lower limb amputation.

Fabrication of Silver Nanoparticles Using a Gas Phase Nanocluster Device and Preliminary Biological Uses

Nanoparticles can be used in a large variety of applications, including magnetic sensing, biological, superconductivity, tissue engineering, and other fields. In this study, we explore the fabrication of gas phase silver nanoparticles using a sputtering evaporation source. This setup composed of a dual magnetron cluster source holds several advantages over other techniques. The system has independent control over the cluster concentration and a wide range of cluster size and materials that can be used for the clusters and for the matrix where it can be embedded. Characterization of these silver nanoparticles was done using transmission electron microscopy (TEM). We obtain a lateral width of 10.6 nm with a dispersion of 0.24 nm. With atomic force microscopy (AFM) a Gaussian fit of this distribution yields and average height of 6.3 nm with a standard deviation of 1.4 nm. We confirm that the deposited silver nanoparticles have a homogenous area distribution, that they have a defined shape and size distribution, and that they are single standing nanoparticles. Given that the scientific literature is not precise regarding the toxic concentration of the nanoparticles, devices such as ours can help clarify these questions. In order to explore further biological applications, we have done preliminary experiments of cell spreading (myoblast adhesion), obtaining interesting morphological changes correlated with the silver concentration on the surface. With a deposited silver concentration ranging from 100–620 ng/cm², the cells showed morphological changes in a short time of 2 h. We conclude that this high precision nanoparticle fabrication technique is adequate for further biological research.

NMR insights on nano silver post-surgical treatment of superficial caseous lymphadenitis in small ruminants

Caseous lymphadenitis (CL), caused by a pathogen of the second class of biosafety – Corynebacterium pseudotuberculosis, is a chronic and severe infectious disease that affects small ruminants and requires long, ineffective treatment which generally leads to animal sacrifice so as to stop the disease spreading. The infected animals suffer the excision of affected superficial lymph nodes and post-surgical treatment with iodine (10% solution in ethanol) and, sometimes, prolonged antibiotic use, but only if the sick animals are of great importance to breeding. Herein, we propose a cheap and easy to apply treatment of CL with excellent results using biogenic silver nanoparticles (AgNP) based technology. AgNP antibacterial properties were investigated in vitro against Corynebacterium pseudotuberculosis cells and in vivo on small ruminants with CL. Treatment of surgical wounds resulting from the excision of superficial CL lesions with a AgNP-based cream was compared to the standard post-surgical treatment method by iodine. Also, the effects of AgNP-based cream treatment were evaluated and compared with the effects of the iodine CL treatment by serum NMR-based metabolomics. Serum samples were collected from 29 animals, 9 sheep and 20 goats, during the treatments and analyzed. All animals showed stable serum metabolomes when iodine or AgNP-based cream effects were compared. The AgNP-based cream treatment showed excellent results, especially in accelerating the healing of wounds, which occurred two to three times faster in comparison with the iodine treatment. AgNP-based cream treatment also prevented CL reappearance and did not cause any side effects on animals. This is the first report on very effective post-surgical treatment of superficial CL in small ruminants based on biogenic silver nanoparticles, which might open up the possibility for a safe veterinary application of AgNP-based cream.

Biogenic nanosilver in a pharmaceutical cream for wound healing in animal and human healthcare.

Recent advancements in biopolymer and metal nanoparticle-based materials in diabetic wound healing management

Currently, diabetes mellitus (DM) accelerated diabetic foot ulcer (DFU) remains vivacious health problem related with delayed healing and high amputation rates which leads to enormous clinical obligation. Keeping in view of the foregoing, researchers have been made in their efforts to develop novel materials which accelerate delayed wound healing in the diabetic patient and reduce the adversative influences of DFUs. The most prominent materials used for the wound healing application have biocompatibility, low cytotoxicity, excellent biodegradable properties, and antimicrobial activity properties. Utilization of nanoparticles has emerged as a protruding scientific and technological revolution in controlling DFUs. Biopolymers in combination with bioactive nanoparticles having antimicrobial, antibacterial, and anti-inflammatory properties have great potential in wound care to enhance the healing process of diabetic wound infectious. Combination of antibacterial nanoparticles like silver nanoparticles (AgNPs), gold nanoparticles (AuNPs), copper nanoparticles (CuNPs) etc. with polymeric matrix could efficiently inhibit bacterial growth and at the same time fastens the healing process of a wound. This review briefed the recent development of different natural polymers and antibacterial nanoparticles to mitigate the diabetes mellitus based DFU.

Biomedical Applications of Silver Nanoparticles: An Up-to-Date Overview

During the past few years, silver nanoparticles (AgNPs) became one of the most investigated and explored nanotechnology-derived nanostructures, given the fact that nanosilver-based materials proved to have interesting, challenging, and promising characteristics suitable for various biomedical applications. Among modern biomedical potential of AgNPs, tremendous interest is oriented toward the therapeutically enhanced personalized healthcare practice. AgNPs proved to have genuine features and impressive potential for the development of novel antimicrobial agents, drug-delivery formulations, detection and diagnosis platforms, biomaterial and medical device coatings, tissue restoration and regeneration materials, complex healthcare condition strategies, and performance-enhanced therapeutic alternatives. Given the impressive biomedical-related potential applications of AgNPs, impressive efforts were undertaken on understanding the intricate mechanisms of their biological interactions and possible toxic effects. Within this review, we focused on the latest data regarding the biomedical use of AgNP-based nanostructures, including aspects related to their potential toxicity, unique physiochemical properties, and biofunctional behaviors, discussing herein the intrinsic anti-inflammatory, antibacterial, antiviral, and antifungal activities of silver-based nanostructures.

Antioxidant and antibacterial activity of silver nanoparticles synthesized by Cestrum nocturnum

Background

Silver nanoparticles are toxic to bacteria and have widespread application in different research areas.

Objective

The aim of this study was to synthesize silver nanoparticles using an aqueous leaf extract of Cestrum nocturnum and to test its antioxidant and antibacterial activities.

Materials and methods

The silver nanoparticles were synthesized by addition of 20 ml extract (8% w/v) with 180 ml silver nitrate solution (1 mM). The synthesis of silver nanoparticles was confirmed by UV–Vis spectrophotometer. The silver nanoparticles were characterized by X-ray diffractometer, Transmission Electron Microscope, Scanning Electron Microscope and Fourier Transform Infra-Red spectroscopy. The antioxidant property of silver nanoparticles was analyzed by the 2, 2-diphenyl-1-picrylhydrazyl, hydrogen peroxide, hydroxyl radical and superoxide radical scavenging methods. The bacteriostatic and bactericidal activity of silver nanoparticles against Escherichiacoli, Enterococcusfaecalis, and Salmonellatyphi was determined using bacterial growth inhibition method. The antibacterial sensitivity and Minimum Inhibitory Concentration (MIC) of silver nanoparticles was determined against the bacteria.

Results

The results confirmed that the silver nanoparticles synthesized by C.nocturnum extract were crystalline in nature, average particle size was 20 nm and were mostly spherical in shape. The antioxidant methods confirmed that the silver nanoparticles have more antioxidant activity as compared to vitamin C. The silver nanoparticles have strong antibacterial (maximum Vibrio cholerae and minimum E. faecalis) activity. The MIC value of silver nanoparticles was 16 μg/ml (Citrobacter), 4 μg/ml (E. faecalis), 16 μg/ml (S. typhi), 8 μg/ml (E. coli), 8 μg/ml (Proteusvulgaris), and 16 μg/ml (V. cholerae).

Conclusion

Green synthesized silver nanoparticles have strong antioxidant and antibacterial activity due to the presence of bioactive molecules on the surface of silver nanoparticles.

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This study focuses on synthesis of silver nanoparticles from medicinal plant in nature.

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The medicinal plant is rich in antioxidant property.

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This study will help the researcher to uncover the antibacterial activity of silver nanoparticles.

Topical delivery of chitosan-capped silver nanoparticles speeds up healing in burn wounds: A preclinical study

This study investigated the effects of topical application of chitosan-capped silver nanoparticles (Ch/AgNPs) on burn wound healing. The chitosan-capped silver nanoparticles were synthesized in one step from the silver nitrate, sodium borohydride, and chitosan and were characterized using transmission electron microscopy, fourier transform infrared spectroscopy, and X-ray diffraction methods. The antioxidant assay was performed to evaluate the scavenging rate. The effects of Ch/AgNPs on burn wound healing was also evaluated by histopathological, molecular, and biochemical evaluations after 7, 14 and 28 days of treatment in a rat model. In comparison to the negative control and silver sulfadiazine groups, the Ch/AgNPs treated wounds exhibited significantly lower inflammatory reaction as determined by the reduced level of interleukin-1β (IL-1β) and neutrophil counts. Treatment by Ch/AgNPs also significantly enhanced re-epithelialization, so that complete epithelialization was achieved in the lesions of the animals of this group, at the 7th day post-wounding. Rapid re-epithelialization, improved granulation tissue formation, reduced IL-1β expression, mild inflammation, and increased transforming growth factor-β1 and basic fibroblast growth factor, at 7 days post-wounding, are convincing reasons to confirm this idea that Ch/AgNPs are effective in speeding up the wound healing stages. Our histopathological findings are in agreement with the molecular and biochemical results and strongly demonstrate that Ch/AgNPs stimulate burn wound healing by decreasing the length of repair phases. Therefore, on the basis of our findings, Ch/AgNPs can be a promising candidate in stimulating wound repair and regeneration.

Antibacterial evaluation of silver nanoparticles synthesized from lychee peel: individual versus antibiotic conjugated effects

This paper describes the extracellular synthesis of silver nanoparticles from waste part of lychee fruit (peel) and their conjugation with selected antibiotics (amoxicillin, cefixim, and streptomycin). FTIR studies revealed the reduction of metallic silver and stabilization of silver nanoparticles and their conjugates due to the presence of CO (carboxyl), OH (hydroxyl) and CH (alkanes) groups. The size of conjugated nanoparticles varied ranging from 3 to 10 nm as shown by XRD. TEM image revealed the spherical shape of biosynthesized silver nanoparticles. Conjugates of amoxicillin and cefixim showed highest antibacterial activity (147.43 and 107.95%, respectively) against Gram-negative bacteria i.e. Alcaligenes faecalis in comparison with their control counterparts. The highest reduction in MIC was noted against Gram-positive strains i.e. Enterococcus faecium (75%) and Microbacterium oxydans (75%) for amoxicillin conjugates. Anova two factor followed by two-tailed t test showed non-significant results both in case of cell leakage and protein estimation between nanoparticles and conjugates of amoxicillin, cefixime and streptomycin. In case of MDA release, non-significant difference among the test samples against the selected strains. Our study found green-synthesized silver nanoparticles as effective antibacterial bullet against both Gram positive and Gram negative bacteria, but they showed a more promising effect on conjugation with selected antibiotics against Gram negative type.