Photodynamic black phosphorus nanosheets functionalized with polymyxin B for targeted ablation of drug-resistant mixed-species biofilms

Biofilms, particularly those formed by multiple bacterial species, pose significant economic and environmental challenges, especially in the context of medical implants. Addressing the urgent need for effective treatment strategies that do not exacerbate drug resistance, we developed a novel nanoformulation, Ce6&PMb@BPN, based on black phosphorus nanosheets (BPN) for targeted treatment of mixed-species biofilms formed by Acinetobacter baumannii (A. baumannii) and methicillin-resistant Staphylococcus aureus (MRSA).The formulation leverages polymyxin B (PMb) for bacterial targeting and chlorin e6 (Ce6) for photodynamic action. Upon near-infrared (NIR) irradiation, Ce6&PMb@BPN efficiently eliminates biofilms by combining chemotherapy, photodynamic therapy (PDT) and photothermal therapy (PTT), reducing biofilm biomass significantly within 30 min. In vivo studies on mice infected with mixed-species biofilm-coated catheters demonstrated the formulation's potent antibacterial and biofilm ablation effects. Moreover, comprehensive biosafety evaluations confirmed the excellent biocompatibility of Ce6&PMb@BPN. Taken together, this intelligently designed nanoformulation holds potential for effectively treating biofilm-associated infections, addressing the urgent need for strategies to combat antibiotic-resistant biofilms, particularly mixed-species biofilm, in medical settings.

In-Vitro Cytotoxic Evaluation of Titanium Dioxide Nanoparticle Using L929 Cell Lines

Tooth movement in orthodontic therapy is connected to the frictional force that is created as the wire passes over the bracket. It is possible for teeth to move quickly when friction is at a minimum. Wires coated with nanoparticles have been found to reduce friction as a result of current developments in the orthodontics sector. Having an antimicrobial property is an added benefit. To reduce the friction generated by brackets, wires, and bands by lessening their cytotoxicity, this study examines the potential use of TiO2 nanoparticles in orthodontics. A monolayer of L929 was utilized in an indirect cytotoxicity test to evaluate the cytotoxicity of the coated orthodontic wire. The absence of reactive zones in our sample data demonstrates that TiO2 is not cytotoxic. Considering the results of our study, we conclude that TiO2 is secure for use as a coating for orthodontic devices.

Molecular marker identification, antioxidant, antinociceptive, and anti-inflammatory responsiveness of malonic acid capped silver nanoparticle

Nano-sized silver has drawn a great deal of attention in the field of health sciences owing to its remarkable therapeutic applications. Interestingly, the method applied to synthesize nanoparticles and the choice of reagents considerably influence their therapeutic potential and toxicities. Current research has explored the toxicity, anti-inflammatory, antinociceptive, and antioxidant responses of the malonic acid-capped silver nanoparticles (MA-AgNPs (C) by using sodium borohydride as a reducing agent at low temperatures by employing both in vitro and in vivo approaches. Furthermore, it has highlighted the synergistic effect of these novel compounds with conventional anti-inflammatory therapeutic agents. Acute and sub-acute toxicity analysis performed following OECD guidelines showed that the studied MA-AgNPs (C) are safer, and prominent toxic signs have not been detected at the highest studied dose of 2,000 mg/kg. Cytotoxicity evaluation through brine shrimp lethality revealed 20% lethality at the highest concentration of 169.8 μg/mL. Significantly, positive anti-inflammatory and analgesic responses alone as well as synergism with the standard were identified through in vitro as well as in vivo methods which were more potent at a lower dose (200 mg/kg). Notably synergistic outcomes were more pronounced than individual ones, indicating their prominent effect as a feasible drug delivery system. IL-6 and TNF-α assessment in excised paw tissue through RTPCR technique further supported their anti-inflammatory potential. DPPH assay revealed eminent in vitro antioxidant activity which was further corroborated by in vivo antioxidant assessment through evaluation of SOD in excised paw tissue.

Acute Toxicity, Anti-diabetic, and Anti-cancerous Potential of Trillium Govanianum-conjugated Silver Nanoparticles in Balb/c Mice

BACKGROUND

The current study aimed to develop an economic plant-based therapeutic agent to improve the treatment strategies for diseases at the nano-scale because Cancer and Diabetes mellitus are major concerns in developing countries. Therefore, in vitro and in vivo antidiabetic and anti-cancerous activities of Trillium govanianum conjugated silver nanoparticles were assessed.

METHODS

In the current study synthesis of silver nanoparticles using Trillium govanianum and characterization were done using a scanning electron microscope, UV-visible spectrophotometer, and FTIR analysis. The in vitro and in vivo anti-diabetic and anti-cancerous potential (200 mg/kg and 400 mg/kg) were carried out.

RESULTS

It was discovered that Balb/c mice did not show any major alterations during observation of acute oral toxicity when administered orally both TGaqu (1000 mg/kg) and TGAgNPs (1000 mg/kg), and results revealed that 1000 mg/kg is not lethal dose as did not find any abnormalities in epidermal and dermal layers when exposed to TGAgNPs. In vitro studies showed that TGAgNPs could not only inhibit alpha-glucosidase and protein kinases but were also potent against the brine shrimp. Though, a significant reduction in blood glucose levels and significant anti-cancerous effects was recorded when alloxan-treated and CCl4-induced mice were treated with TGAgNPs and TGaqu.

CONCLUSION

Both in vivo and in vitro studies revealed that TGaqu and TGAgNPs are not toxic at 200 mg/kg, 400 mg/kg, and 1000 mg/kg doses and possess strong anti-diabetic and anti-cancerous effects due to the presence of phyto-constituents. Further, suggesting that green synthesized silver nanoparticles could be used in pharmaceutical industries to develop potent therapeutic agents.

The protective effect of silver nanoparticles' on epithelial cornea cells against ultraviolet is accompanied by changes in calcium homeostasis and a decrease of the P2X7 and P2Y2 receptors

PURPOSE

The aim of the study was to evaluate the effect of silver nanoparticles hydrocolloids (AgNPs) on human corneal epithelial cells. Epithelial cells form the outermost and the most vulnerable to environmental stimuli layer of the cornea in the eye. Mechanical stress, UV radiation, and pathogens such as bacteria, viruses, and parasites challenge the fragile homeostasis of the eye. To help combat stress, infection, and inflammation wide portfolio of interventions is available. One of the oldest treatments is colloidal silver. Silver nanoparticle suspension in water is known for its anti-bacterial anti-viral and antiprotozoal action. However, AgNPs interact also with host cells, and the character of the interplay between corneal cells and silver seeks investigation.

METHODS

The human epithelial corneal cell line (HCE-2) was cultured in vitro, treated with AgNPs, and subjected to UV. The cell's viability, migration, calcium concentration, and expression/protein level of selected proteins were investigated by appropriate methods including cytotoxicity tests, "wound healing" assay, Fluo8/Fura2 AM staining, qRT-PCR, and western blot.

RESULTS

Incubation of human corneal cells (HCE-2) with AgNP did not affect cells viability but limited cells migration and resulted in altered calcium homeostasis, decreased the presence of ATP-activated P2X7, P2Y2 receptors, and enhanced the expression of PACAP. Furthermore, AgNPs pretreatment helped restrain some of the deleterious effects of UV irradiation. Interestingly, AgNPs had no impact on the protein level of ACE2, which is important in light of potential SARS-CoV-2 entrance through the cornea.

CONCLUSIONS

Silver nanoparticles are safe for corneal epithelial cells in vitro.

Novel metal peroxide nanoboxes restrain Clostridioides difficile infection beyond the bactericidal and sporicidal activity

Clostridioides difficile spores are considered as the major source responsible for the development of C. difficile infection (CDI), which is associated with an increased risk of death in patients and has become an important issue in infection control of nosocomial infections. Current treatment against CDI still relies on antibiotics, which also damage normal flora and increase the risk of CDI recurrence. Therefore, alternative therapies that are more effective against C. difficile bacteria and spores are urgently needed. Here, we designed an oxidation process using H2O2 containing PBS solution to generate Cl- and peroxide molecules that further process Ag and Au ions to form nanoboxes with Ag-Au peroxide coat covering Au shell and AgCl core (AgAu-based nanoboxes). The AgAu-based nanoboxes efficiently disrupted the membrane structure of bacteria/spores of C. difficile after 30-45 min exposure to the highly reactive Ag/Au peroxide surface of the nano structures. The Au-enclosed AgCl provided sustained suppression of the growth of 2 × 107 pathogenic Escherichia coli for up to 19 days. In a fecal bench ex vivo test and in vivo CDI murine model, biocompatibility and therapeutic efficacy of the AuAg nanoboxes to attenuate CDI was demonstrated by restoring the gut microbiota and colon mucosal structure. The treatment successfully rescued the CDI mice from death and prevented their recurrence mediated by vancomycin treatment. The significant outcomes indicated that the new peroxide-derived AgAu-based nanoboxes possess great potential for future translation into clinical application as a new alternative therapeutic strategy against CDI.

Iron oxide/silver hybrid nanoparticles impair the cholinergic system and cause reprotoxicity in Caenorhabditis elegans

Iron oxide nanoparticles present superparamagnetic properties that enable their application in various areas, including drug delivery at specific locations in the organism. Silver nanoparticles have potent antimicrobial effects. Although the combination of Fe3O4-NPs and Ag-NPs in one hybrid nanostructure (Fe3O4@Ag-NPs) demonstrated promising targeted biomedical applications, their toxicological effects are unknown and need to be assessed. Caenorhabditis elegans is a promising model for nanotoxicological analysis, as it allows an initial screening of new substances. After exposure to Fe3O4-NPs, Ag-NPs and Fe3O4@Ag-NPs, we observed that hybrid NPs reduced the C. elegans survival and reproduction. Higher concentrations of Fe3O4@Ag-NPs caused an increase in cell apoptosis in the germline and a decrease in egg laying, which was associated with a decrease in worm swimming movements and abnormalities in the cholinergic neurons. Fe3O4@Ag-NPs caused an increase in reactive oxygen species, along with activation of DAF-16 transcription factor. A higher expression of the target genes GST-4::GFP and SOD-3::GFP were evidenced, which suggests the activation of the antioxidant system. Our results indicate the reprotoxicity caused by high levels of Fe3O4@Ag-NPs, as well as cholinergic neurotoxicity and activation of the antioxidant system in C. elegans, suggesting that high concentrations of these nanomaterials can be harmful to living organisms.

Toxicological Aspects, Safety Assessment, and Green Toxicology of Silver Nanoparticles (AgNPs)—Critical Review: State of the Art

In recent years, research on silver nanoparticles (AgNPs) has attracted considerable interest among scientists because of, among other things, their alternative application to well-known medical agents with antibacterial properties. The size of the silver nanoparticles ranges from 1 to 100 nm. In this paper, we review the progress of research on AgNPs with respect to the synthesis, applications, and toxicological safety of AgNPs, and the issue of in vivo and in vitro research on silver nanoparticles. AgNPs’ synthesis methods include physical, chemical, and biological routes, as well as “green synthesis”. The content of this article covers issues related to the disadvantages of physical and chemical methods, which are expensive and can also have toxicity. This review pays special attention to AgNP biosafety concerns, such as potential toxicity to cells, tissues, and organs.

Genotoxicity and Toxicity Assessment of a Formulation Containing Silver Nanoparticles and Kaolin: An In Vivo Integrative Approach

A new material composed of a kaolin base with silver nanoparticles (AgNPs) attached to its surface was developed, as an alternative to antibiotics used as supplements in animal feed. As part of its safety assessment, an in vivo geno-toxicological evaluation of this material was conducted in rats. First, a preliminary dose finding study was carried out to decide the doses to be tested in the main study: 50, 300 and 2000 mg/kg b.w. For the main study, a combined strategy composed of the MN test (TG 474) and the comet assay (TG 489), integrated in a repeated dose 28-day oral toxicity study (TG 407), was performed. A No Observed Adverse Effect Level (NOAEL) of 2000 mg of the silver-kaolin formulation/kg b.w. by oral route, for 28 days, was determined. The silver-kaolin formulation did not induce micronuclei in bone marrow, or DNA strand breaks (SBs) or alkali labile sites (ALS) in liver, spleen, kidney or duodenum at any dose. The modified Fpg comet assay did not reveal oxidized bases in the same tissues at the dose of 2000 mg/kg b.w. Silver was quantified by ICP-MS in all the target organs, confirming the negative results obtained under these conditions.

Toxicological Evaluation of Silver Nanoparticles Synthesized with Peel Extract of Stenocereus queretaroensis

Silver nanoparticles (AgNPs) synthesized with plants are widely used in different industries, such as the medical, industrial, and food industries; however, their hazards and risks remain unclear. Here, we aimed to evaluate the toxicological effects of AgNPs in both in vitro and in vivo models. Previously, we developed and characterized green synthesized AgNPs based on Stenocereus queretaroensis (S. queretaroensis). The present study evaluates the toxicity of these AgNPs through cytotoxicity and mutagenicity tests in vitro, as well as genotoxicity tests, including the evaluation of acute oral, dermal, and inhalation toxicity, along with dermal and ocular irritation, in vivo, according to guidelines of The Organization for Economic Co-operation and Development (OECD). We evaluated cell cytotoxicity in L929 cells, and the half-maximal inhibitory concentration was 134.76 µg/mL. AgNPs did not cause genotoxic or mutagenic effects. Furthermore, in vivo oral, dermal, and acute inhalation toxicity results did not show any adverse effects or mortality in the test animals, and after the dermal and ocular irritation assessments, the in vivo models did not exhibit irritation or corrosion. Therefore, the results show that these previously synthesized S. queretaroensis AgNPs do not represent a risk at the tested concentrations; however, little is known about the effects that AgNPs induce on physiological systems or the possible risk following long-term exposure.

In Vivo Effects of Orally Administered Different Concentrations of Silver Oxide Nanoparticles in Hyperuricemic Mice

Silver oxide nanoparticles (AgO-NPs) antioxidant, anti-cancer, anti-microbial, and tissue repair properties. Gouty arthritis is the inflammation of tissues and joints caused by the deposition of monosodium urate crystals. In this experiment, we investigated the anti-hyperuricemic effectiveness of different concentrations of AgO-NPs in mice. The present study aimed to investigate the effect of administration of AgO-NPs in monosodium urate (MSU)-induced gouty mice for the very first time. Monosodium urate (MSU) crystals were administered intraperitoneal for gout induction, followed by 5, 10, and 20 µg/mL doses of AgO-NPs for 2 weeks. The positive control was provided with the commercially available drug allopurinol to compare the effects of AgO-NPs and allopurinol. The main purpose of the study was to investigate the effectiveness of the nanoparticles in comparison with commercially available drugs. AgO-NPs have been shown to improve the condition of gouty arthritis by reducing significantly (P ˂ 0.001) increased levels of ALT, AST, and total bilirubin. The total protein estimation results showed significant improvement at concentration of 20 µg/mL of AgO-NPs. The lipid profile results showed that high concentration (20 µg/mL) of AgO-NPs decrease the lipid content significantly as compared to control. It was concluded from this study that the antioxidant, anti-inflammatory, and antilipidemic properties of AgO-NPs may improve the hyperuricemic condition in gouty arthritis mice.

Superior in vivo Wound-Healing Activity of Mycosynthesized Silver Nanogel on Different Wound Models in Rat

Wound healing is a complex phenomenon particularly owing to the rise in antimicrobial resistance. This has attracted the attention of the scientific community to search for new alternative solutions. Among these, silver being antimicrobial has been used since ancient times. Considering this fact, the main goal of our study was to evaluate the wound-healing ability of mycofabricated silver nanoparticles (AgNPs). We have focused on the formulation of silver nanogel for the management of wounds in albino Wistar rats. Mycosynthesized AgNPs from Fusarium oxysporum were used for the development of novel wound-healing antimicrobial silver nanogel with different concentrations of AgNPs, i.e., 0.1, 0.5, and 1 mg g^-1. The formulated silver nanogel demonstrated excellent wound-healing activity in the incision, excision, and burn wound-healing model. In the incision wound-healing model, silver nanogel at a concentration of 0.5 mg g^-1 exhibited superior wound-healing effect, whereas in the case of excision and burn wound-healing model, silver nanogel at the concentrations of 0.1 and 1 mg g^-1 showed enhanced wound-healing effect, respectively. Moreover, silver nanogel competently arrests the bacterial growth on the wound surface and offers an improved local environment for scald wound healing. Histological studies of healed tissues and organs of the rat stated that AgNPs at less concentration (1 mg g^-1) do not show any toxic or adverse effect on the body and promote wound healing of animal tissue. Based on these studies, we concluded that the silver nanogel prepared from mycosynthesized AgNPs can be used as a promising antimicrobial wound dressing.

Gut microbiome and plasma metabolome changes in rats after oral gavage of nanoparticles: sensitive indicators of possible adverse health effects

BACKGROUND

The oral uptake of nanoparticles is an important route of human exposure and requires solid models for hazard assessment. While the systemic availability is generally low, ingestion may not only affect gastrointestinal tissues but also intestinal microbes. The gut microbiota contributes essentially to human health, whereas gut microbial dysbiosis is known to promote several intestinal and extra-intestinal diseases. Gut microbiota-derived metabolites, which are found in the blood stream, serve as key molecular mediators of host metabolism and immunity.

RESULTS

Gut microbiota and the plasma metabolome were analyzed in male Wistar rats receiving either SiO2 (1000 mg/kg body weight/day) or Ag nanoparticles (100 mg/kg body weight/day) during a 28-day oral gavage study. Comprehensive clinical, histopathological and hematological examinations showed no signs of nanoparticle-induced toxicity. In contrast, the gut microbiota was affected by both nanoparticles, with significant alterations at all analyzed taxonomical levels. Treatments with each of the nanoparticles led to an increased abundance of Prevotellaceae, a family with gut species known to be correlated with intestinal inflammation. Only in Ag nanoparticle-exposed animals, Akkermansia, a genus known for its protective impact on the intestinal barrier was depleted to hardly detectable levels. In SiO2 nanoparticles-treated animals, several genera were significantly reduced, including probiotics such as Enterococcus. From the analysis of 231 plasma metabolites, we found 18 metabolites to be significantly altered in Ag-or SiO2 nanoparticles-treated rats. For most of these metabolites, an association with gut microbiota has been reported previously. Strikingly, both nanoparticle-treatments led to a significant reduction of gut microbiota-derived indole-3-acetic acid in plasma. This ligand of the arylhydrocarbon receptor is critical for regulating immunity, stem cell maintenance, cellular differentiation and xenobiotic-metabolizing enzymes.

CONCLUSIONS

The combined profiling of intestinal microbiome and plasma metabolome may serve as an early and sensitive indicator of gut microbiome changes induced by orally administered nanoparticles; this will help to recognize potential adverse effects of these changes to the host.

Development and Characterization of Curcumin-Silver Nanoparticles as a Promising Formulation to Test on Human Pterygium-Derived Keratinocytes

Pterygium is a progressive disease of the human eye arising from sub-conjunctival tissue and extending onto the cornea. Due to its invasive growth, pterygium can reach the pupil compromising visual function. Currently available medical treatments have limited success in suppressing efficiently the disease. Previous studies have demonstrated that curcumin, polyphenol isolated from the rhizome of Curcuma longa, induces apoptosis of human pterygium fibroblasts in a dose- and time-dependent manner showing promising activity in the treatment of this ophthalmic disease. However, this molecule is not very soluble in water in either neutral or acidic pH and is only slightly more soluble in alkaline conditions, while its dissolving in organic solvents drastically reduces its potential use for biomedical applications. A nanoformulation of curcumin stabilized silver nanoparticles (Cur-AgNPs) seems an effective strategy to increase the bioavailability of curcumin without inducing toxic effects. In fact, silver nitrates have been used safely for the treatment of many ophthalmic conditions and diseases for a long time and the concentration of AgNPs in this formulation is quite low. The synthesis of this new compound was achieved through a modified Bettini's method adapted to improve the quality of the product intended for human use. Indeed, the pH of the reaction was changed to 9, the temperature of the reaction was increased from 90 °C to 100 °C and after the synthesis the Cur-AgNPs were dispersed in Borax buffer using a dialysis step to improve the biocompatibility of the formulation. This new compound will be able to deliver both components (curcumin and silver) at the same time to the affected tissue, representing an alternative and a more sophisticated strategy for the treatment of human pterygium. Further in vitro and in vivo assays will be required to validate this formulation.

Assessment of the Therapeutic Efficacy of Silver Nanoparticles against Secondary Cystic Echinococcosis in BALB/c Mice

Background: Cystic echinococcosis (CE) is a highly prevalent parasitic disease resulting from the hydatid cyst of Echinococcus granulosus. It is also described as a zoonotic disease and considered a neglected tropical infection. Aim: This study assessed the antiparasitic activity of silver nanoparticles (AgNPs), against E. granulosus infection in BALB/c mice. Methods: The green synthesis of AgNPs was accomplished using Zizyphus spina-christi leaves. AgNPs were orally administered to BALB/c mice for acute short-term toxicity evaluation, in doses of 50 mg, 100 mg, 200 mg, and 300 mg/kg, and observations for toxic signs were carried out at 24, 48 h, and 14 days, continuously. Moreover, a total of 20 mice divided into two groups were intraperitoneally administered with 1500 viable protoscoleces for secondary hydatidosis infection. Results: The results showed that AgNPs did not induce any adverse effects or signs and no death, in either group of mice. The histopathological findings in the liver, kidneys, and intestine of the mice administered with AgNPs revealed mild histological effects compared with the control ones. The treated-infected mice showed a change in the appearance of the liver hydatid cysts from hyaline to milky cloudy compared with the untreated infected mice. Conclusion: Biosynthesized AgNPs showed anti-hydatic effects and are suggested as anti-echinococcal cyst treatment.

Nano-enabled strategies to combat methicillin-resistant Staphylococcus aureus

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) has become a threat to global health because of limited treatments. MRSA infections are difficult to treat due to increasingly developing resistance in combination with protective biofilms of Staphylococcus aureus (S. aureus). Nanotechnology-based research revealed that effective MRSA treatments could be achieved through targeted nanoparticles (NPs) that withstand biological films and drug resistance. Thus, the principal aim towards improving MRSA treatment is to advance drug delivery tools, which successfully address the delivery-related problems. These potential delivery tools would also carry drugs to the desired sites of therapeutic action to overcome the adverse effects. This review focused on different types of nano-engineered carriers system for antimicrobial agents with improved therapeutic efficacy of entrapped drugs. The structural characteristics that play an essential role in the effectiveness of delivery systems have also been addressed with a description of recent scientific advances in antimicrobial treatment, emphasizing challenges in MRSA treatments. Consequently, existing gaps in the literature are highlighted, and reported contradictions are identified, allowing for the development of roadmaps for future research.

Safety assessment of bio-synthesized iodine-doped silver nanoparticle wound ointment in experimental rats

Background

In the wake of antibiotic resistance, treatment of intractable wound have been very challenging and any alternative treatment which may lead to less use of antibiotics deserves further exploitation. Nanoparticle conjugates has potentially not only reduce antibiotic use but it has been considered safe and effectively disinfect wounds already colonized with resistant bacteria as well as promoting granulation tissue formation. In this study, Iodine-doped silver nanoparticle Ointment (Ag-I NPs) was investigated for its toxicological effect on excisional wound of albino rats.

Methods

Aqueous extraction of Piper guineense leaf was carried out and used for the synthesis of Ag-I NPs. The synthesized Ag-I NPs were characterized by Ultraviolet visible spectrophotometer which confirmed the availability of silver nanoparticles. The particles were then used to prepare a wound healing ointment for treating excision wound inflicted on wistar rat model. Blood samples, liver and kidney biopsies were collected on the 21st day of the experiment from all the rats for hematology, biochemical and histopathological analysis.

Result

In the hematological and biochemical analysis, hemoglobin (Hb), packed cell volume (PCV) and mean corpuscular hemoglobin (MCH), superoxide dismutase (SOD), alkaline phosphatase (ALP) of experimental rats treated with Ag-I NPs were significantly different (p < 0.05) compared to the untreated group. In the histopathology, the photomicrograph of the liver showed the normal control, PEG, Ag-NP, and Ag-I NP groups remained intact displaying distinctive histo-morphological appearance and stable cell density while the untreated (UTD) group showed fatty liver and reduced cellular density. The kidney photomicrograph of the normal control and Ag- I NP groups were present with intact renal corpuscles while the other photomicrographs displayed corpuscular degeneration marked by the large halo-spaced bowman space.

Conclusion

Silver nanoparticles (Ag NPs) and iodine-doped silver nanoparticle (Ag-I NP) altered haematological parameters in the rats and also influenced some biochemical changes in the serum of the rats. While in the histopathological study, the antioxidant present in the plant extract used to synthesize Ag NPs and Ag I-NPs may have functioned in synergy to maintain and preserve the integrity of the hepatocytes and renal corpuscles of the rats.

Current Knowledge of Silver and Gold Nanoparticles in Laboratory Research-Application, Toxicity, Cellular Uptake

Silver and gold nanoparticles can be found in a range of household products related to almost every area of life, including patches, bandages, paints, sportswear, personal care products, food storage equipment, cosmetics, disinfectants, etc. Their confirmed ability to enter the organism through respiratory and digestive systems, skin, and crossing the blood-brain barrier raises questions of their potential effect on cell function. Therefore, this manuscript aimed to summarize recent reports concerning the influence of variables such as size, shape, concentration, type of coating, or incubation time, on effects of gold and silver nanoparticles on cultured cell lines. Due to the increasingly common use of AgNP and AuNP in multiple branches of the industry, further studies on the effects of nanoparticles on different types of cells and the general natural environment are needed to enable their long-term use. However, some environmentally friendly solutions to chemically synthesized nanoparticles are also investigated, such as plant-based synthesis methods.

Histopathological Changes of Organs (Lungs, Liver, Kidney, and Brain) After Using Two Types of AgiCoat and Acticoat Nanosilver Dressings on Deep Second-Degree Burn in Rat

Prevention of infections is a very important issue in treating the burn wounds. The nanosilver dressings have many promising advantages, but absorption of silver ions and its adverse effects to the body were always a question. The aim of this study was to compare Silver serum levels and acute toxic effects of nanosilver on histopathology of organs (lungs, liver, kidney, spleen, and brain) in two types of AgiCoat and Acticoat (nanosilver) dressings on second-degree deep burn in rat. This is an experimental study conducted in our animal laboratory. We divided 24 Sprague-Dawley male rats weighing 300 to 350 randomly into two groups. After anesthesia, a second deep-degree burn was made over dorsal skins of rats by standard method. For group A, Agicoat and, for group B, Acticoat dressings were used. The dressings were changed every 3 days with AgiCoat and Acticoat, respectively. After 14 days, we got blood samples and tissue samples taken from heart, liver, kidneys, spleen, lungs, and brain and a sample from dorsal skin of the rat for histopathological examinations. The results showed that the levels of serum silver in both groups were significantly higher than the standard level (1.22 part per million (PM); AgiCoat, P = .017; Acticoat, P = .000), but there was no significant difference between the groups (P = .551). Examination of the relationship between the level of serum silver and histopathological changes in liver showed that hepatotoxicity of AgiCoat was higher compared with Acticoat and the difference was significant (P = .002). There were no pathological changes in brain, kidneys, spleen, heart, and lungs. Wound healing was faster in Acticoat group. The nanosilver dressings can cause toxicity in liver but not in kidney, brain, spleen, heart, and lungs. Liver pathology and hepatotoxicity were more prominent in AgiCoat group. Wound healing was faster in Acticoat group.

Formulation and Evaluation of Linum usitatissimum Mucilage-Based Nanoparticles for Effective Delivery of Ezetimibe

Introduction

The aim of current study was to prepare Linum usitatissimum mucilage (LUM) based nanoparticles, capable of encapsulating hydrophobic drug ezetimibe as nanocarriers.

Methods

Solvent evaporation and nanoprecipitation techniques were used to develop nanoparticles by encapsulating ezetimibe in the articulated matrix of polysaccharide fractions. Developed nanoparticles were characterized to determine the particle size, zeta potential, polydispersibility index (PDI), and entrapment efficiency (EE). Morphology and physicochemical characterization were carried out through SEM, FTIR, PXRD and thermal analysis. Saturation solubility and in vitro release studies were also performed. Safety assessment of ezetimibe loaded nanoparticles was evaluated via oral acute toxicity study.

Results

The mean particle size, zeta potential, PDI and EE for emulsion solvent evaporation were 683.6 nm, -28.3 mV, 0.39, 63.7% and for nanoprecipitation were 637.7 nm, 0.07, -27.1 mV and 80%, respectively. Thermal analysis confirmed enhanced thermal stability, whereas PXRD confirmed amorphous nature of drug. Saturation solubility (p-value <0.05) demonstrated improved solubility of drug when enclosed in linseed nanoparticles. Nanoprecipitation surpasses emulsion solvent evaporation in dissolution test by possessing smaller size. Acute oral toxicity study indicated no significant changes in behavioral, clinical or histopathological parameters of control and experimental groups.

Conclusion

The in vitro release of ezetimibe was augmented by enhancing aqueous solubility through devised nanoparticles. Thus, linseed mucilage could act as biopolymer in the fabrication of nanoparticle formulation. The acute oral toxicological investigations provided evidence that LUMNs were safe after oral administration.

Disruption of brain conductivity and permittivity and neurotransmitters induced by citrate-coated silver nanoparticles in male rats

As one of the most exonerative, competitive, and abundant nanoparticles in curative uses, silver nanoparticles (AgNPs) play a growing important role in developing global neurodegeneration. Herein, we inspected the neurotoxic and histopathological effects of the oral dose of 26.9 nm citrate-coated AgNPs (100 and 1000 mg/kgbw, 28 days) on the brain conductivity and permittivity combined with neurotransmitter assays. While male mice in the control group were given deionized water. In terms of biophysical levels, the brain electric conductivity and relative permittivity were significantly decreased in the 26.9 nm citrate-coated AgNP treated groups versus the controls. Besides, 26.9 nm citrate-coated AgNP treatment resulted in a significant deficiency in the concentrations of brain acetylcholine esterase, dopamine, and serotonin. Total brain contents of silver ion significantly increased in a dose-dependent manner. Further, light and electron microscopy revealed a progressive disruption in the lamellar pattern of the myelinated axons of the nerve fibers, in addition to the accumulation of nanosilver in lysosomes and swollen mitochondria in axoplasm. In conclusion, 26.9 nm citrate-coated AgNPs are capable of gaining access to the brain of mice and causing electric conductivity and relative permittivity damage along with a high degree of cellular toxicity in the brain tissue. Therefore, the present study highlights, for the first time, the adverse effects of the citrate-coated AgNPs to the brain of mice and raises the concern of their probable neurotoxic impacts which is helpful for conclusive interpretation of future behavioral and potential neurodegeneration-based aspects. It would be of interest to investigate citrate-coated AgNPs mediated axonal relevant-signal transduction levels in future studies.

Nanomaterials as drug delivery systems with antibacterial properties: current trends and future priorities

Introduction:Despite extensive advances in the production and synthesis of antibiotics, infectious diseases are one of the main problems of the 21st century due to multidrug-resistant (MDR) distributing in organisms. Therefore, researchers in nanotechnology have focused on new strategies to formulate and synthesis the different types of nanoparticles (NPs) with antimicrobial properties.Areas covered:The present review focuses on nanoparticles which are divided into two groups, organic (micelles, liposomes, polymer-based and lipid-based NPs) and inorganic (metals and metal oxides). NPs can penetrate the cell wall then destroy permeability of cell membrane, the structure and function of cell macromolecules by producing of reactive oxygen species (ROS) and eventually kill the bacteria. Moreover, their characteristics and mechanism in various bacteria especially MDR bacteria and finally their biocompatibility and the factors affecting their activity have been discussed.Expert opinion:Nanotechnology has led to higher drug absorption, targeted drug delivery and fewer side effects. NPs can overcome MDR through affecting several targets in the bacteria cell and synergistically increase the effectiveness of current antibiotics. Moreover, organic NPs with regard to their biodegradability and biocompatibility characteristics can be suitable agents for medical applications. However, they are less stable in environment in comparison to inorganic NPs.

Biosynthesis of Novel Silver Nanoparticles Using Eryngium thyrsoideum Boiss Extract and Comparison of their Antidiabetic Activity with Chemical Synthesized Silver Nanoparticles in Diabetic Rats

In the present study, silver nanoparticles (1) were synthesized by green method using Eryngium campestre Boiss aqueous extract and silver nanoparticles (2) were synthesized with chemical method. The silver nanoparticles (1) and (2) were characterized with FT-IR, UV-Vis, XRD, EDX, SEM, and TEM analyses. The effects of silver nanoparticles (1) and (2) were investigated on glucose, hematology, and blood biochemical parameters in alloxan- induced diabetes type 1 model rats. Diabetic or intact rats received intraperitoneal injection of saline or 2.5 mg/kg of silver nanoparticles (1) and (2) for 14 consecutive days. Hematological parameters and serum concentration of FBS, HbA₁C, ALT, AST, GGT, ALP, albumin, creatinine, and urea were determined. Interestingly, silver NPs (1) or (2) did not exert toxic influences on hematological parameters and liver and kidney function in intact rats. Both silver nanoparticles (1) and (2) exert hypoglycemic effects in diabetic rats. They did not alter urea, creatinine, and hematological parameters except white blood cell (WBC) count in diabetic rats. Silver nanoparticles (1) decreased significantly liver enzyme levels including ALT and AST of diabetic rats. However silver nanoparticles (2) could not suppress the increased levels of liver enzymes in diabetic rats. In comparison with silver nanoparticles (2), the silver nanoparticles (1) are more protective than the same dose of silver nanoparticles (2) in the regulation and improving the liver function in diabetic rats. Also, silver nanoparticles (1) may exert protective effects on liver damage of diabetic rats rather than kidney damage.

Evaluation of the neurotoxic effects of engineered nanomaterials in C57BL/6J mice in 28-day oral exposure studies

In recent years, concerns have emerged about the potential neurotoxic effects of engineered nanomaterials (NMs). Titanium dioxide and silver are among the most widely used types of metallic NMs. We have investigated the effects of these NMs on behaviour and neuropathology in male and female C57BL/6J mice following 28-day oral exposure with or without a 14-day post-exposure recovery. The mice were fed ad libitum with food pellets dosed with 10 mg/g TiO₂, 2 mg/g polyvinylpyrrolidone-coated Ag or control pellets. Behaviour was evaluated by X-maze, open field, string suspension and rotarod tests. Histological alterations were analysed by immunohistochemistry and brain tissue homogenates were investigated for markers of oxidative stress, inflammation and blood-brain barrier disruption. Effects of the NMs on tyrosine and serine/threonine protein kinase activity in mouse brains were investigated by measuring kinase activity on peptide microarrays. Markers of inflammation, oxidative stress and blood-brain barrier integrity were not significantly affected in the male and female mice following exposure to Ag or TiO₂. Both types of NMs also revealed no consistent significant treatment-related effects on anxiety and cognition. However, in the Ag NM exposed mice altered motor performance effects were observed by the rotarod test that differed between sexes. At 1-week post-exposure, a diminished performance in this test was observed exclusively in the female animals. Cortex tissues of female mice also showed a pronounced increase in tyrosine kinase activity following 28 days oral exposure to Ag NM. A subsequent Inductively Coupled Plasma - Mass Spectrometry (ICP-MS) based toxicokinetic study in female mice revealed a rapid and persistent accumulation of Ag in various internal organs including liver, kidney, spleen and the brain up to 4 weeks post-exposure. In conclusion, our study demonstrated that subacute exposure to foodborne TiO₂ and Ag NMs does not cause substantial neuropathological changes in mice. However, the toxicokinetic and specific toxicodynamic findings indicate that long-term exposures to Ag NM can cause neurotoxicity, possibly in a sex-dependent manner.

Evaluation of Polyacrylonitrile Nonwoven Mats and Silver-Gold Bimetallic Nanoparticle-Decorated Nonwoven Mats for Potential Promotion of Wound Healing In Vitro and In Vivo and Bone Growth In Vitro

We prepared polyacrylonitrile (PAN) and urchin-like Ag-Au bimetallic or Ag nanoparticle-decorated PAN nonwoven mats using electrospinning and evaluated them in vitro and in vivo for wound healing, antibacterial effects on skin tissue, and promotion of bone ingrowth in vitro. A facile, green, low-temperature protocol was developed to obtain these nonwoven mats. The sterilization rate of urchin-like Ag-Au bimetallic and Ag nanoparticle-decorated PAN nonwoven mats against Staphylococcus aureus was 96.81 ± 2.81% and 51.90 ± 9.07%, respectively, after 5 h treatment. In an in vitro cell model, these two mats did not show significant toxicity; cell viability of >80% was obtained within 5 h of treatment. In vivo animal model preclinical assessment showed that the urchin-like Ag-Au bimetallic nonwoven mat group showed significant wound recovery because of sebaceous gland, hair follicle, and fat formation during skin tissue regeneration; increased neovascularization and compact collagen fibers were observed in the dermal layer, comparable to the findings for the control group. The mother substrate of the urchin-like Ag-Au bimetallic nanoparticle-decorated PAN nonwoven mats, that is, pure PAN nonwoven mats, was found to be a potential scaffold for bone tissue engineering as osteoblast ingrowth from the top to the bottom of the membrane and proliferation inside the membrane were observed. The key genetic factor Cbfa1 was identified as a key osteoblast differentiation regulator in vitro. Thus, electrospun membrane materials show potential for use as dual-functional biomaterials for bone regeneration and infection control and composite grafts for infectious bone and soft tissue defects.

All That Glitters Is Not Silver-A New Look at Microbiological and Medical Applications of Silver Nanoparticles

Silver and its nanoparticles (AgNPs) have different faces, providing different applications. In recent years, the number of positive nanosilver applications has increased substantially. It has been proven that AgNPs inhibit the growth and survival of bacteria, including human and animal pathogens, as well as fungi, protozoa and arthropods. Silver nanoparticles are known from their antiviral and anti-cancer properties; however, they are also very popular in medical and pharmaceutical nanoengineering as carriers for precise delivery of therapeutic compounds, in the diagnostics of different diseases and in optics and chemistry, where they act as sensors, conductors and substrates for various syntheses. The activity of AgNPs has not been fully discovered; therefore, we need interdisciplinary research to fulfil this knowledge. New forms of products with silver will certainly find application in the future treatment of many complicated and difficult to treat diseases. There is still a lack of appropriate and precise legal condition regarding the circulation of nanomaterials and the rules governing their safety use. The relatively low toxicity, relative biocompatibility and selectivity of nanoparticle interaction combined with the unusual biological properties allow their use in animal production as well as in bioengineering and medicine. Despite a quite big knowledge on this topic, there is still a need to organize the data on AgNPs in relation to specific microorganisms such as bacteria, viruses or fungi. We decided to put this knowledge together and try to show positive and negative effects on prokaryotic and eukaryotic cells.

Emerging Nano-Formulations and Nanomedicines Applications for Ocular Drug Delivery

Ocular diseases can deteriorate vision to the point of blindness and thus can have a major impact on the daily life of an individual. Conventional therapies are unable to provide absolute therapy for all ocular diseases due to the several limitations during drug delivery across the blood-retinal barrier, making it a major clinical challenge. With recent developments, the vast number of publications undergird the need for nanotechnology-based drug delivery systems in treating ocular diseases. The tool of nanotechnology provides several essential advantages, including sustained drug release and specific tissue targeting. Additionally, comprehensive in vitro and in vivo studies have suggested a better uptake of nanoparticles across ocular barriers. Nanoparticles can overcome the blood-retinal barrier and consequently increase ocular penetration and improve the bioavailability of the drug. In this review, we aim to summarize the development of organic and inorganic nanoparticles for ophthalmic applications. We highlight the potential nanoformulations in clinical trials as well as the products that have become a commercial reality.

New Protein-Coated Silver Nanoparticles: Characterization, Antitumor and Amoebicidal Activity, Antiproliferative Selectivity, Genotoxicity, and Biocompatibility Evaluation

Nanomaterials quickly evolve to produce safe and effective biomedical alternatives, mainly silver nanoparticles (AgNPs). The AgNPs' antibacterial, antiviral, and antitumor properties convert them into a recurrent scaffold to produce new treatment options. This work reported the full characterization of a highly biocompatible protein-coated AgNPs formulation and their selective antitumor and amoebicidal activity. The protein-coated AgNPs formulation exhibits a half-inhibitory concentration (IC₅₀) = 19.7 µM (2.3 µg/mL) that is almost 10 times more potent than carboplatin (first-line chemotherapeutic agent) to inhibit the proliferation of the highly aggressive human adenocarcinoma HCT-15. The main death pathway elicited by AgNPs on HCT-15 is apoptosis, which is probably stimulated by reactive oxygen species (ROS) overproduction on mitochondria. A concentration of 111 µM (600 µg/mL) of metallic silver contained in AgNPs produces neither cytotoxic nor genotoxic damage on human peripheral blood lymphocytes. Thus, the AgNPs formulation evaluated in this work improves both the antiproliferative potency on HCT-15 cultures and cytotoxic selectivity ten times more than carboplatin. A similar mechanism is suggested for the antiproliferative activity observed on HM1-IMSS trophozoites (IC₅₀ = 69.2 µM; 7.4 µg/mL). There is no change in cell viability on mice primary cultures of brain, liver, spleen, and kidney exposed to an AgNPs concentration range from 5.5 µM to 5.5 mM (0.6 to 600 µg/mL). The lethal dose was determined following the OECD guideline 420 for Acute Oral Toxicity Assay, obtaining an LD₅₀ = 2618 mg of Ag/Kg body weight. All mice survived the observational period; the histopathology and biochemical analysis show no differences compared with the negative control group. In summary, all results from toxicological evaluation suggest a Category 5 (practically nontoxic) of the Globally Harmonized System of Classification and Labelling of Chemicals for that protein-coated AgNPs after oral administration for a short period and urge the completion of its preclinical toxicological profile. These findings open new opportunities in the development of selective, safe, and effective AgNPs formulations for the treatment of cancer and parasitic diseases with a significant reduction of side effects.

Biocompatibility of Biomaterials for Nanoencapsulation: Current Approaches

Nanoencapsulation is an approach to circumvent shortcomings such as reduced bioavailability, undesirable side effects, frequent dosing and unpleasant organoleptic properties of conventional drug delivery systems. The process of nanoencapsulation involves the use of biomaterials such as surfactants and/or polymers, often in combination with charge inducers and/or ligands for targeting. The biomaterials selected for nanoencapsulation processes must be as biocompatible as possible. The type(s) of biomaterials used for different nanoencapsulation approaches are highlighted and their use and applicability with regard to haemo- and, histocompatibility, cytotoxicity, genotoxicity and carcinogenesis are discussed.

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.

Noble Metals and Soft Bio-Inspired Nanoparticles in Retinal Diseases Treatment: A Perspective

We are witnessing an exponential increase in the use of different nanomaterials in a plethora of biomedical fields. We are all aware of how nanoparticles (NPs) have influenced and revolutionized the way we supply drugs or how to use them as therapeutic agents thanks to their tunable physico-chemical properties. However, there is still a niche of applications where NP have not yet been widely explored. This is the field of ocular delivery and NP-based therapy, which characterizes the topic of the current review. In particular, many efforts are being made to develop nanosystems capable of reaching deeper sections of the eye such as the retina. Particular attention will be given here to noble metal (gold and silver), and to polymeric nanoparticles, systems consisting of lipid bilayers such as liposomes or vesicles based on nonionic surfactant. We will report here the most relevant literature on the use of different types of NPs for an efficient delivery of drugs and bio-macromolecules to the eyes or as active therapeutic tools.

Safety Assessment of Nanomaterials to Eyes: An Important but Neglected Issue

The production and application of nanomaterials have grown tremendously during last few decades. The widespread exposure of nanoparticles to the public is provoking great concerns regarding their toxicity to the human body. However, in comparison with the extensive studies carried out to examine nanoparticle toxicity to the human body/organs, one especially vulnerable organ, the eye, is always neglected. Although it is a small part of the body, 90% of outside information is obtained via the ocular system. In addition, eyes usually directly interact with the surrounding environment, which may get severer damage from toxic nanoparticles compared to inner organs. Therefore, the study of assessing the potential nanoparticle toxicity to the eyes is of great importance. Here, the recent advance of some representative manufactured nanomaterials on ocular toxicity is summarized. First, a brief introduction of ocular anatomy and disorders related to particulate matter exposure is presented. Following, the factors that may influence toxicity of nanoparticles to the eye are emphasized. Next, the studies of representative manufactured nanoparticles on eye toxicity are summarized and classified. Finally, the limitations that are associated with current nanoparticle-eye toxicity research are proposed.

Silver nanoparticles engineered by thermal co-reduction approach induces liver damage in Wistar rats: acute and sub-chronic toxicity analysis

Recently, nanotechnology applications have increased tremendously in consumer products. However, it has been observed that these nanoparticles can cause a potential risk to the environment as well as human health. In the present manuscript, we have analyzed acute and sub-chronic toxicity of engineered silver nanoparticles (AgNPs) by assessing the impact on Wistar rats. AgNPs were synthesized by a novel approach-thermal co-reduction-with spherical shape and a uniform size distribution of 60 nm. The estimated LD₅₀ value was observed to be more than 2000 mg/kg bw in acute toxicity studies. Sub-chronic toxicity indicated impairment of liver and kidney enzymes and various hematological and biochemical parameters. Tissue distribution studies indicated the target organ for accumulation is liver after treatment with AgNP. Particle deposition and congestion was observed in major organs-though, and heart and pancreatic tissues were not affected even by the higher doses. On the basis of the observations of this study, it is concluded that up to 40 mg/kgbw is a safer dose of AgNPs (60 nm, engineered by thermal co-reduction approach) and further research will be required to validate the long-term accumulation in body. In addition, it can also be considered by policymakers for the safer use of AgNPs.

In vitro and in vivo toxicity assessment of biologically synthesized silver nanoparticles from Elaeodendron croceum

Background The cytotoxic properties of nanoparticles have attracted a great deal of attention in the field of nanoscience and nanotechnology due to their small size and ability to penetrate cellular membranes. Methods The silver nanoparticles were synthesized using Elaeodendron croceum stem bark and characterized. The oral acute toxicity studies were carried out by administration of 500, 1000, 2000 mg/kg body weight to Wister rats in respective groups. An in vitro cytotoxicity assay was evaluated in MDA-MB-231 breast cancer cells using the WST-1 Cell Proliferation assay. The percentage of cell viability after treatment with aqueous extracts of Elaeodendron croceum (ECE) and Elaeodendron croceum silver nanoparticles (ECAgNPs) was compared with that of paclitaxel. Results The in vivo studies revealed that the LD50 was higher than 2000 mg/kg and there was no significant difference (p>0.05) between the treatment groups compared with the control group for mean organ-to-body weight ratio except in the liver and in all hematological parameters except WBC and hematocrit. Similarly, there was no significant difference (p>0.05) for serum electrolytes (Na+, Mg2+ K+, Cl-, and Ca2+), total protein, urea, ɣ-glutamyl transferase (GGT), Aspartate aminotransferase (AST), Alkaline phosphatase (ALP), Alanine aminotransferase (ALT), albumin, total and conjugated bilirubin between the treatment and the control group. However, there were changes in creatinine, urea, and cholesterol. In the in vitro assays, ECE and ECAgNPs showed IC50 values of 70.87±2.99 and 138.8±3.98 µg/mL respectively against MDA-MB-231 cells compared to paclitaxel, which showed an IC50 value of 80 ng/mL. Conclusion The results showed that the LD50 of the ECE and ECAgNPs in Wister rats was determined to be greater than 2000 mg/kg body weight. The aqueous extract also showed more cytotoxic than the ECAgNPs suggesting that the toxic compounds in aqueous extract were involved in the capping of the AgNPs.

Metal nanoparticles restrict the growth of protozoan parasites

The Trypanosoma and Toxoplasma spp, are etiological agents of diseases capable of causing significant morbidity, mortality and economic burden, predominantly in developing countries. Currently, there are no effective vaccines for the diseases caused by these parasites; therefore, therapy relies heavily on antiprotozoal drugs. However, the treatment options for these parasitic diseases are limited, thus underscoring the need for new anti-protozoal agents. Here, we investigated the anti-parasite action of nanoparticles. We found that the nanoparticles have strong and selective in vitro activity against T. b. brucei but moderate in vitro activity against T. congolense and T. evansi. An estimation of the in vitro anti-Trypanosoma efficacy showed that the nanoparticles had ≥200-fold selective activity against the parasite versus mammalian cells. Moreover, the nanoparticle alloys moderately suppressed the in vitro growth of T. gondii by ≥60%. In our in vivo study, the nanoparticles appeared to exhibit a trypanostatic effect, but did not totally suppress the rat parasite burden, thereby failing to appreciably extend the survival time of infected animals compared with the untreated control. In conclusion, this is the first study to demonstrate the selective in vitro anti-Trypanosoma action of nanoparticles and thus supports the potential of nanoparticles as alternative anti-parasitic agents.

Silver Oxide Coatings with High Silver-Ion Elution Rates and Characterization of Bactericidal Activity

This paper reports the synthesis and characterization of silver oxide films for use as bactericidal coatings. Synthesis parameters, dissolution/elution rate, and bactericidal efficacy are reported. Synthesis conditions were developed to create AgO, Ag₂O, or mixtures of AgO and Ag₂O on surfaces by reactive magnetron sputtering. The coatings demonstrate strong adhesion to many substrate materials and impede the growth of all bacterial strains tested. The coatings are effective in killing Escherichia coli and Staphylococcus aureus, demonstrating a clear zone-of-inhibition against bacteria growing on solid media and the ability to rapidly inhibit bacterial growth in planktonic culture. Additionally, the coatings exhibit very high elution of silver ions under conditions that mimic dynamic fluid flow ranging between 0.003 and 0.07 ppm/min depending on the media conditions. The elution of silver ions from the AgO/Ag₂O surfaces was directly impacted by the complexity of the elution media, with a reduction in elution rate when examined in complex cell culture media. Both E. coli and S. aureus were shown to bind ~1 ppm Ag⁺/mL culture. The elution of Ag⁺ resulted in no increases in mammalian cell apoptosis after 24 h exposure compared to control, but apoptotic cells increased to ~35% by 48 and 72 h of exposure. Taken together, the AgO/Ag₂O coatings described are effective in eliciting antibacterial activity and have potential for application on a wide variety of surfaces and devices.

Inhibition of the Quorum Sensing System (ComDE Pathway) by Aromatic 1,3-di-m-tolylurea (DMTU): Cariostatic Effect with Fluoride in Wistar Rats

Dental caries occurs as a result of dysbiosis among commensal and pathogenic bacteria leading to demineralization of enamel within a dental biofilm (plaque) as a consequence of lower pH in the oral cavity. In our previous study, we have reported 1,3-disubstituted ureas particularly, 1,3-di-m-tolylurea (DMTU) could inhibit the biofilm formation along with lower concentrations of fluoride (31.25 ppm) without affecting bacterial growth. In the present study, RT-qPCR analysis showed the target specific molecular mechanism of DMTU. In vivo treatment with DMTU, alone or in combination with fluoride, resulted in inhibition of caries (biofilm development of Streptococcus mutans) using a Wistar rat model for dental caries. The histopathological analysis reported the development of lesions on dentine in infected subjects whereas the dentines of treated rodents were found to be intact and healthy. Reduction in inflammatory markers in rodents' blood and liver samples was observed when treated with DMTU. Collectively, data speculate that DMTU is an effective anti-biofilm and anti-inflammatory agent, which may improve the cariostatic properties of fluoride.

A study on the in vitro percutaneous absorption of silver nanoparticles in combination with aluminum chloride, methyl paraben or di-n-butyl phthalate

Some reports indicate that the silver released from dermally applied products containing silver nanoparticles (AgNP) (e.g. wound dressings or cosmetics) can penetrate the skin, particularly if damaged. AgNP were also shown to have cytotoxic and genotoxic activity. In the present study percutaneous absorption of AgNP of two different nominal sizes (Ag15nm or Ag45nm by STEM) and surface modification, i.e. citrate or PEG stabilized nanoparticles, in combination with cosmetic ingredients, i.e. aluminum chloride (AlCl₃), methyl paraben (MPB), or di-n-butyl phthalate (DBPH) was assessed using in vitro model based on dermatomed pig skin. The inductively coupled plasma mass spectrometry (ICP-MS) measurements after 24h in receptor fluid indicated low, but detectable silver absorption and no statistically significant differences in the penetration between the 4 types of AgNP studied at 47, 470 or 750μg/ml. Similarly, no significant differences were observed for silver penetration when the AgNP were used in combinations with AlCl₃ (500μM), MPB (1250μM) or DBPH (35μM). The measured highest amount of Ag that penetrated was 0.45ng/cm² (0.365-0.974ng/cm²) for PEG stabilized Ag15nm+MPB.

Mechanistic Basis of Antimicrobial Actions of Silver Nanoparticles

Multidrug resistance of the pathogenic microorganisms to the antimicrobial drugs has become a major impediment toward successful diagnosis and management of infectious diseases. Recent advancements in nanotechnology-based medicines have opened new horizons for combating multidrug resistance in microorganisms. In particular, the use of silver nanoparticles (AgNPs) as a potent antibacterial agent has received much attention. The most critical physico-chemical parameters that affect the antimicrobial potential of AgNPs include size, shape, surface charge, concentration and colloidal state. AgNPs exhibits their antimicrobial potential through multifaceted mechanisms. AgNPs adhesion to microbial cells, penetration inside the cells, ROS and free radical generation, and modulation of microbial signal transduction pathways have been recognized as the most prominent modes of antimicrobial action. On the other side, AgNPs exposure to human cells induces cytotoxicity, genotoxicity, and inflammatory response in human cells in a cell-type dependent manner. This has raised concerns regarding use of AgNPs in therapeutics and drug delivery. We have summarized the emerging endeavors that address current challenges in relation to safe use of AgNPs in therapeutics and drug delivery platforms. Based on research done so far, we believe that AgNPs can be engineered so as to increase their efficacy, stability, specificity, biosafety and biocompatibility. In this regard, three perspectives research directions have been suggested that include (1) synthesizing AgNPs with controlled physico-chemical properties, (2) examining microbial development of resistance toward AgNPs, and (3) ascertaining the susceptibility of cytoxicity, genotoxicity, and inflammatory response to human cells upon AgNPs exposure.

Fabrication of transparent quaternized PVA/silver nanocomposite hydrogel and its evaluation as an antimicrobial patch for wound care systems

Grafting of quaternary nitrogen atoms into the backbone of polymer is an efficient way of developing new generation antimicrobial polymeric wound dressing. In this study, an elastic, non-adhesive and antimicrobial transparent hydrogel based dressing has been designed, which might be helpful for routine observation of wound area without removing the dressing material along with maintaining a sterile environment for a longer period of time. Green synthesized silver nanoparticles have been loaded into the quaternized PVA hydrogel matrix to improve its antimicrobial property. Silver nanoparticles loaded quaternized PVA hydrogel showed enhanced mechanical and swelling properties compared to native quaternized PVA hydrogel. Release kinetics evaluated by atomic absorption spectroscopy revealed that the release mechanism of silver nanoparticles from the hydrogel follows Fickian diffusion. Antimicrobial efficacy of the hydrogels was evaluated by disk diffusion test on Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli. After 96 h of release in phosphate buffer, the growth inhibition zone created by silver nanoparticless loaded quaternized PVA hydrogel is comparable to that created by ampicillin. These observations assert that the silver nanoparticles loaded quaternized PVA hydrogel acts as a reservoir of silver nanoparticles, which helps in maintaining a sterile environment for longer time duration by releasing Ag nanocrystallite in sustained manner.

Silver acetate exposure: Effects on reproduction and post natal development

Effects of oral silver acetate exposure were assessed in P generation and F generation post-natal day 26 rats. Male and female Sprague Dawley rats (n = 20 each) were exposed to silver acetate at 0.4, 4.0 or 40.0 mg/kg bw in their drinking water for 10 weeks prior to and during mating. Females were exposed to silver acetate throughout gestation and lactation. Clinical signs, body weight, feed and fluid consumption were recorded regularly. Decreased mean daily fluid consumption was observed in male and female animals during the 10 week pre mating period and during gestation in the 40 mg/kg bw dose group. Decreased fertility was observed in the 40 mg/kg bw dose group. Decreased feed consumption was observed across all dose groups and decreased mean daily fluid consumption was observed in the 4.0 mg/kg dose group during lactation. Decreased implant numbers, mean numbers of pups born/litter and numbers of live pups born/litter was observed in the 40 mg/kg bw dose group. Pup weight was reduced on lactation days 0, 4 and 7 (males) and 4, 7 and 21 (females) in the 4.0 mg/kg bw dose group and in males at lactation day 21 (40 mg/kg bw dose group). Runting was observed in males (Lactation Day; LD 4) and female (LD 4 and 7) animals in the 4.0 mg/kg bw dose group. Reduced postnatal-day 26 pup weight was observed in male pups in the 40 mg/kg bw dose group and female pups in the 4.0 mg/kg bw dose group.

Electron microscopic ultrastructural study on the toxicological effects of AgNPs on the liver, kidney and spleen tissues of albino mice

The present study deals with the intraperitoneal administration of 500, 1000, 3000, and 5000mg/kg of AgNPs in albino mice for 28 days to evaluate the potential toxicological effects of AgNPs on blood biochemical parameters and to investigate the light and electron microscopic histopathological alterations on three major targets organs i.e., liver, kidney and spleen. The AgNPs was well tolerated and no mortality was observed even at the highest dose i.e., 5000mg/kg. Mice treated with 500 and 1000mg/kg AgNPs did not show significant behavioral, biochemical and ultrastructural pathological changes. Mice treated with 1000mg/kg AgNPs produces little ultrastructural alteration in liver, kidney and spleen. However, mice treated with 3000 and 5000mg/kg AgNPs revealed significant changes in biochemical parameters. Electron microscopic ultrastructural investigation of liver and kidney shows that the administration of 3000 and 5000mg/kg AgNPs revealed irregularity in the nuclear membrane, nuclear chromatin condensations, degenerated hepatocytes, swollen and pleomorphic mitochondria with distorted cristae, extensive dilation of rough endoplasmic reticulum, destructed cytoplasm, hypertrophied and fused podocytes and thickened basement membrane in the endothelial cells of the proximal tubules. The spleen sections at 3000 and 5000mg/kg AgNPs revealed megakaryocytes hyperplasia, lobulations, invaginations and folding of nuclei and nuclear membrane. The present research indicates that AgNPs were well tolerated at the lower doses, but significant alterations in liver, kidney and spleen were observed at the higher doses tested. It is, therefore, suggested that further studies are needed for the minimization of the observed side effects, especially at higher doses before AgNPs being applied in pharmaceutical application.