Broad-spectrum bioactivities of silver nanoparticles: the emerging trends and future prospects

Introducing a Novel Chemotherapeutic Drug for the Treatment of Lung Adenocarcinoma: Silver Nanoparticles Green-formulated by Cinnamomum verum

In this study we report the green synthesis of nontoxic, stable, and small size silver nanoparticle by Cinnamomum verum with reducing/capping ability without any toxic reducing agents. The in situ prepared AgNPs were characterized by advanced physicochemical techniques like FE-SEM, TEM, and UV-Vis study. It has been established that AgNPs have a spherical shape with a mean diameter from 10 to 45 nm. In the antioxidant test, the IC50 of AgNPs and BHT against DPPH free radicals were 191 and 242 µg/mL, respectively. In the cellular and molecular part of the recent study, the treated cells with AgNPs were assessed by MTT assay for 48 h about the cytotoxicity and anti-human lung adenocarcinoma properties on normal (HUVEC) and lung adenocarcinoma cell lines i.e. PC-14, LC-2/ad, and HLC-1. The IC50 of AgNPs were 259, 291, and 395 µg/mL against PC-14, LC-2/ad, and HLC-1 cell lines, respectively. The viability of malignant lung cell line reduced dose-dependently in the presence of AgNPs.

Nanomaterials for Postharvest Management of Insect Pests: Current State and Future Perspectives

Globally, between one quarter and one-third of total grains produced each year are lost during storage mainly through infestation of insect pests. Among the available control options such as chemical and physical techniques, fumigation with aluminum phosphide (AlP) is so far considered the best control strategy against storage insect pests. However, these insect pests are now developing resistance against AIP due to its indiscriminate use due to non-availability of any effective alternative control option. Resistance to AIP among storage insect pests is increasing, and its inhalation has shown adverse effects on animals and human beings. Nanotechnology has opened up a wide range of opportunities in various fields such as agriculture (pesticides, fertilizers, etc.), pharmaceuticals, and electronics. One of the applications of nanotechnology is the usage of nanomaterial-based insecticide formulations for mitigating field and storage insect pests. Several formulations, namely, nanoemulsions, nanosuspensions, controlled release formulations, and solid-based nanopesticides, have been developed with different modes of action and application. The major advantage is their small size which helps in proper spreading on the pest surface, and thus, better action than conventional pesticides is achieved. Besides their minute size, these have no or reduced harmful effects on non-target species. Nanopesticides can therefore provide green and efficient alternatives for the management of insect pests of field and storage. However, an outcry against the utilization of nano-based pesticides is also revealed. It is considered by some that nano-insecticides may also have hazardous effects on humans as well as on the environment. Due to limited available data, nanopesticides have become a double-edged weapon. Therefore, nanomaterials need to be evaluated extensively for their large-scale adoption. In this article, we reviewed the nanoformulations that are developed and have proved effective against the insect pests under postharvest storage of grains.

Role of Salvia officinalis Silver Nanoparticles in Attenuation Renal Damage in Rabbits Exposed to Methotrexate

Nanomaterials are now considered in an extensive range of applications in various fields such as biotechnology and biomedicine. The present study aimed to investigate the protective role of Salvia officinalis Silver Nanoparticles (SOSNPs) as an anti-oxidant on nephrotic damage induced by methotrexate (MTX) in adult rabbits. Green silver nanoparticles were synthesized using alcoholic extract of Salvia officinalis (S. Officinalis) leaves and were characterized by UV-spectrophotometry and scanning electron microscope. The mixing of the plant extract of S. Officinalis with silver nitrate solution leads to the change of the reaction mixture color to yellowish within 1 h and dark brown after 8 h. For studying the protective role of SOSNPs, a total of 28 adult Wistar albino rabbits were divided into four groups and treated intramuscularly (twice per week) for 45 days as follows: T1: S. Officinalis (150 mg/kg B.W), T2: SOSNPs (150 mg/kg B.W); T3: MTX (0.25 mg/kg B.W) and SOSNPs (150 mg/kg B.W); T4: MTX (0.25 mg/kg B.W). Blood was collected at 0, 15, 30, and 45 days using retro-orbital sinus and cardiac puncture technique, and the serum factors including malondialdehyde (MDA), glutathione (GSH) in serum, creatinine, as well as blood urea nitrogen and uric acid concentrations were measured at the next step. The results indicated that MTX (T4) caused a case of oxidative stress by a significant decrease in GSH and MDA as well as an increase in serum creatinine, urea, and uric acid concentrations. On the other hand, the protective roles of S. Officinalis and SOSNPs given concurrently with MTX were clarified in T2 and T3 groups, where there was the alleviation of renal damage through the correction of the previously mentioned parameters as well as the correction of anti-oxidant status. Finally, the present study documented the anti-oxidant activity and renal protective effects of SOSNPs against the damaging effects of MTX in rabbits.

Antiviral Properties of Streptomyces tuirus DBZ39 Mediated Gold Nanoparticles Against Bluetongue virus

<b>Background and Objective:</b> The proposed study involves the approach from the point of anti-viral activity of gold nanoparticles against the <i>Bluetongue virus</i>. Among viral diseases, Bluetongue is regarded as an economically scouring disease. Neither a vaccine nor an antiviral drug is available for the prevention or treatment of this disease. The antiviral activity of gold nanoparticles synthesized by a novel isolate of <i>Streptomyces tuirus</i> DBZ39 is the breakthrough of the study. <i>Streptomyces tuirus </i>DBZ39, a novel isolate obtained from alkaline soil was proved to be efficient actinomycetes, for the extracellular synthesis of gold nanoparticles. <b>Materials and Methods:</b> An upstream bioprocess was optimized and developed for the synthesis of controlled size gold nanoparticles with solitary mono dispersal pattern in aurum chloride solution. The characterization and confirmation of gold nanoparticles were illustrated by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Analysis (EDAX) and Fourier Transmission Infrared Radiation Analysis (FTIR). <b>Results:</b> Biomass size of 3 g, substrate concentration of 1 mM, pH of 8.5 and temperature of 45°C were observed as optimum conditions for the synthesis of 15-24 nm size gold nanoparticles. The <i>Bluetongue virus</i> (BTV) which belongs to the genus Orbivirus in the family Reoviridae with 26 serotypes is an etiological agent of infectious and non-contagious Bluetongue disease of main sheep and several other domestic animals. <b>Conclusion:</b> Gold nanoparticles for the 1st time, at a higher concentration of 1:64 dilutions revealed a very promising and novel antiviral property against the <i>Bluetongue virus</i>.

Nano-silver functionalized polysaccharides as a platform for wound dressings: A review

The healing of defected skin tissue is a complex process, especially for chronic wounds. Poor healing of these wounds may cause extensive suffering and high cost for patients. Traditional wound dressings are typically designed for a single function and they cannot satisfy all requirements for the whole process of wound healing. Therefore, it is necessary to develop new types of wound dressings with multiple functions for wound healing. In particular, adding an antibacterial function has been shown to be of great benefit during tissue repair. Nano‑silver is widely used in wound treatment because of various advantages, such as its wide antibacterial spectrum and lower drug resistance. Therefore, wound dressings loaded with nano‑silver have attracted widespread attention in wound healing. Naturally derived polysaccharides hold great potential as wound dressings, because of their abundant availability, low prices and good biocompatibility. In this review, nano‑silver functionalized polysaccharide-based wound dressings are systematically reviewed, including their preparation methods, antibacterial performances and classification of nano‑silver wound dressings. Moreover, the toxicity of nano‑silver based wound dressings is discussed and the prospective research direction is elaborated. This review aims to provide readers with an overview of the latest developments in silver nanotechnology, and to provide a little guidance for the research of nano‑silver functionalized polysaccharide-based wound dressings.

Biologically formed silver nanoparticles and in vitro study of their antimicrobial activities on resistant pathogens

Background and Objectives:

Silver nanoparticles (AgNPs) have been found to have multiple uses as antibacterial, antifungal and anti-biofilm agents because of their biological activities and safety. The present study was aimed to analyze the antimicrobial and anti-biofilm activities as well as the cytotoxic effect of AgNPs against different human pathogens.

Materials and Methods:

AgNPs were synthesized using cell free supernatants of Escherichia coli (ATCC 25922), Enterococcus faecalis (ATCC 19433), Pseudomonas aeruginosa (ATCC 27856), Enterobacter cloacae (ATCC 13047) and Penicillium oxalicum strain, then were analyzed using UV/Vis Spectral Analysis, Transmission electron microscopy (TEM). Scanning Electron Microscope (SEM) and Energy Dispersive-X-ray Spectroscopy (EDX) analysis. Antimicrobial activities of biosynthesized AgNPs were assessed with selected antimicrobial agents against multidrug resistant bacteria and candida. Anti-biofilm and cytotoxicity assays of these biosynthesized AgNPs were also done.

Results:

The synthesis of AgNPs were confirmed through observed color change and monitoring UV-Vis spectrum which showed homogeneous (little agglomeration) distribution of silver nanoparticles. TEM and SEM have shown that the particle size ranged from 13 to 34 (nm) with spherical shape and a high signal with EDX analysis. Antibacterial and antifungal efficacy of antibiotics and fluconazole were increased in combination with biosynthesized AgNPs against resistant bacteria and candida. Significant reduction in biofilm formation was found better with Penicillium oxalicum AgNPs against biofilm forming bacteria.

Conclusion:

Penicillium oxalicum has the best effect towards synthesizing AgNPs, for antimicrobial activities against resistant bacteria and candida, in addition to anti-biofilm activities against biofilm forming Staphylococcus aureus and E. coli and the safest cytotoxicity effect on (MRC-5) cell line.

Silver-Protein Nanocomposites as Antimicrobial Agents

The use of nanomaterials alone or in composites with proteins is a promising alternative to inhibit pathogenic bacteria. In this regard, this study used seed proteins from both fenugreek (Trigonella foenum-graecum L.) (FNP) and mung bean (Viga radiate) (MNP), with silver nanoparticles (Ag-NPs) and nanocomposites of either Ag-NPs plus FNP (Ag-FNP) or Ag-NPs plus MNP (Ag-MNP) as inhibitory agents against pathogenic bacteria. FNP and MNP were isolated from fenugreek seeds and mung bean seeds, respectively, and fractionated using Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE). Both FNP and MNP were immobilized with Ag-NPs to synthesize the nanocomposites Ag-FNP and Ag-MNP, respectively. The physicochemical characteristics of Ag-NPs and their composites with proteins were studied by X-ray Diffraction (XRD), dynamic light scattering (DLS), the zeta potential, Scanning and Transmission Electron Microscopy (SEM and TEM, respectively), Atomic Force Microscopy (AFM), and the Brunauer-Emmett-Teller isotherm (BET), elucidating their structural parameters, size distribution, size charges, size surface morphology, particle shape, dimensional forms of particles, and specific surface area, respectively. The sole proteins, Ag-NPs, and their nanocomposites inhibited pathogenic Gram-positive and Gram-negative bacteria. The inhibitory activities of both nanocomposites (Ag-FNP and Ag-MNP) were more than those obtained by either Ag-NPs or proteins (FNP, MNP). Minimum inhibitory concentrations (MICs) of Ag-FNP were very low (20 and 10 µg mL-1) against Salmonellatyphimurium and Pseudomonasaerugenosa, respectively, but higher (162 µg mL-1) against E. coli and Listeriamonocytogenes. MICs of Ag-MNP were also very low (20 µg mL-1) against Staphylococcusaureus but higher (325 µg mL-1) against Listeriamonocytogenes. TEM images of Staphylococcusaureus and Salmonellatyphimurium, treated with Ag-FNP and Ag-MNP, at their MIC values, showed asymmetric, wrinkled exterior surfaces, cell deformations, cell depressions, and diminished cell numbers.

Assessment of the Antibacterial Potential of Biosynthesized Silver Nanoparticles Combined with Vancomycin Against Methicillin-Resistant Staphylococcus aureus-Induced Infection in Rats

Methicillin-resistant Staphylococcus aureus (MRSA) is considered one of the most serious multidrug-resistant bacteria worldwide. MRSA resistance to methicillin antibiotics made vancomycin, the acceptable treatment option. Silver nanoparticles (Ag-NPs) are among the well-known antibacterial substances showing multimode antibacterial action. Therefore, Ag-NPs are appropriate applicants for use in combination with vancomycin in order to augment its antibacterial action. This study aimed to biosynthesize silver nanoparticles and to evaluate its antibacterial activity against MRSA alone and when combined with vancomycin both in vitro and in vivo. Agaricus bisporus is used to reduce the silver nitrate salts in solution to yield silver nanoparticles which was characterized by UV-visible spectrophotometric analysis that shows maximum absorption at 420 nm as a preliminary confirmation for nanoparticles synthesis, Energy-Dispersive Analysis of X-ray (EDX) which confirms the crystalline nature of silver nanoparticles and transmission electron microscopy (TEM) image shows the particles in spherical form with mean size 27.45 nm. The synthesized silver nanoparticles were tested for antibacterial activity against MRSA, and the synergetic effects of the combination of silver nanoparticles and vancomycin were evaluated. The results showed a strong synergistic antibacterial effect between Ag-NPs and vancomycin in vitro with fractional inhibitory concentration 0.37 and in vivo against MRSA strain. The result revealed that mycosynthesized silver nanoparticles (NPs) enhance the in vitro and in vivo antibacterial activity of vancomycin against MRSA. These results suggested that sliver nanoparticles have an effective antibacterial activity against MRSA count, histopathology, and liver enzymes as well as protective immune response specially when combined with vancomycin in the lungs of infected rats with MRSA.

Therapeutics studies and biological properties of Teucrium polium (Lamiaceae)

Teucrium polium has been used in traditional medicine as antifungal, antipyretic, antispasmodic, and antibacterial. It is consumed by many jordanians for the treatment of many diseases. The effects of this plant have been investigated in kidney, liver, and brain. Its antidiabetic, antimicrobial, antioxidant, and anticancer effects have been introduced. Polyphenolic compound, flavonoids, monoterpenes, alkanoides, and essential oils were identified. Several studies revealed that this plant has a hypoglycemic effect and can help to control blood sugar. It was reported that plants containing flavonoids and phenolics compounds exhibit a large array of biological activities like genotoxicity (chromosomal aberrations and sister chromatid exchange) and oxidative stress damage. These phytochemicals are found in herbal and vegetables plants, as well as being reliably protective against oxidative stress damage and lipid peroxidation. In addition, T. polium has secondary effects on different organs, namely liver, kidney and at high doses this plant becomes toxic. In conclusion, this review investigates many pharmacologicals properties and side effects of T. polium.

Synthesis of silver nanoparticles using Plantago lanceolata extract and assessing their antibacterial and antioxidant activities

Silver nanoparticles (Ag. NPs) have shown a biological activity range, synthesized under different environment-friendly approaches. Ag. NPs were synthesized using aqueous crude extract (ACE) isolated from Plantago lanceolata. The ACE and Ag. NPs were characterized and assessed their biological and antioxidant activities. The existence of nanoparticles (NPs) was confirmed by color shift, atomic force microscopy (AFM), and UV-Vis's spectroscopy. The FT-IR analysis indicated the association of biomolecules (phenolic acid and flavonoids) to reduce silver (Ag⁺) ions. The SEM study demonstrated a sphere-shaped and mean size in the range of 30 ± 4 nm. The EDX spectrum revealed that the Ag. NPs were composed of 54.87% Ag with 20 nm size as identified by SEM and TEM. AFM has ended up being exceptionally useful in deciding morphological elements and the distance across of Ag. NPs in the scope of 23-30 nm. The TEM image showed aggregations of NPs and physical interaction. Ag. NPs formation also confirmed by XPS, DRS and BET studies. Ag. NPs showed efficient activity as compared to ACE, and finally, the bacterial growth was impaired by biogenic NPs. The lethal dose (LD₅₀) of Ag. NPs against Agrobacterium tumefaciens, Proteus vulgaris, Staphylococcus aureus, and Escherichia coli were 45.66%, 139.71%, 332.87%, and 45.54%, with IC50 (08.02 ± 0.68), (55.78 ± 1.01), (12.34 ± 1.35) and (11.68 ± 1.42) respectively, suppressing the growth as compared to ACE. The antioxidant capacity, i.e., 2,2-diphenyl-1-picrylhydrazyl (DPPH) of Ag. NPs were assayed. ACE and Ag. NPs achieved a peak antioxidant capacity of 62.43 ± 2.4 and 16.85 ± 0.4 μg mL^-1, compared to standard (69.60 ± 1.1 at 100 μg mL^-1) with IC₅₀ (369.5 ± 13.42 and 159.5 ± 10.52 respectively). Finally, the Ag. NPs synthesized by P. lanceolata extract have an excellent source of bioactive natural products (NP). Outstanding antioxidant, antibacterial activities have been shown by NPs and can be used in various biological techniques in future research.

Antibacterial Activity of Kaolin-Silver Nanomaterials: Alternative Approach to the Use of Antibiotics in Animal Production

According to the search for alternatives to replace antibiotics in animal production suggested in the antimicrobial resistance action plans around the world, the objective of this work was to evaluate the bactericidal effect of kaolin-silver nanomaterial for its possible inclusion as an additive in animal feed. The antibacterial activity of the C3 (kaolin-silver nanomaterial) product was tested against a wide spectrum of Gram-negative and Gram-positive bacteria (including multidrug resistant strains) by performing antibiograms, minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC), as well as growth inhibition curves against seven strains causing infections in animals. The C3 product generated inhibition halos in all the tested strains, and a higher activity against Gram-negative bacteria was found, with MBC values ranged from 7.8 µg/mL (P. aeruginosa) to 15.6 µg/mL (E. coli and Salmonella). In contrast, it was necessary to increase the concentration to 31.3 µg/mL or 250 µg/mL to eliminate 99.9% of the initial population of S. aureus ATCC 6538 and E. faecium ATCC 19434, respectively. Conversely, the inhibition growth curves showed a faster bactericidal activity against Gram-negative bacteria (between 2 and 4 h), while it took at least 24 h to observe a reduction in cell viability of S. aureus ATCC 6538. In short, this study shows that the kaolin-silver nanomaterials developed in the framework of the INTERREG POCTEFA EFA183/16/OUTBIOTICS project exhibit antibacterial activity against a wide spectrum of bacteria. However, additional studies on animal safety and environmental impact are necessary to evaluate the effectiveness of the proposed alternative in the context of One Health.

Antiviral nanoparticles for sanitizing surfaces: A roadmap to self-sterilizing against COVID-19

Nanoparticles provide new opportunities in merging therapeutics and new materials, with current research efforts just beginning to scratch the surface of their diverse benefits and potential applications. One such application, the use of inorganic nanoparticles in antiseptic coatings to prevent pathogen transmission and infection, has seen promising developments. Notably, the high reactive surface area to volume ratio and unique chemical properties of metal-based nanoparticles enables their potent inactivation of viruses. Nanoparticles exert their virucidal action through mechanisms including inhibition of virus-cell receptor binding, reactive oxygen species oxidation and destructive displacement bonding with key viral structures. The prevention of viral outbreaks is one of the foremost challenges to medical science today, emphasizing the importance of research efforts to develop nanoparticles for preventative antiviral applications. In this review, the use of nanoparticles to inactivate other viruses, such as influenza, HIV-1, or norovirus, among others, will be discussed to extrapolate broad-spectrum antiviral mechanisms that could also inhibit SARS-CoV-2 pathogenesis. This review analyzes the published literature to highlight the current state of knowledge regarding the efficacy of metal-based nanoparticles and other antiviral materials for biomedical, sterile polymer, and surface coating applications.

Biochemical and histological alterations induced by nickel oxide nanoparticles in the ground beetle Blaps polychresta (Forskl, 1775) (Coleoptera: Tenebrionidae)

The present study evaluates the effect of nickel oxide nanoparticles on some biochemical parameters and midgut tissues in the ground beetle Blaps polychresta as an indicator organism for nanotoxicity. Serial doses of the NiO-NPs colloid (0.01, 0.02, 0.03, 0.04, 0.05, and 0.06 mg/g) were prepared for injecting into the adult beetles. Insect survival was reported daily for 30 days, and the sublethal dose of 0.02 mg/g NiO-NPs was selected for the tested parameters. After the treatment, nickel was detected in the midgut tissues by X-ray microanalysis. The treated group demonstrated a significant increase in aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities when compared to the untreated group. However, the treated group demonstrated a significant decrease in ascorbate peroxidase (APOX) activity when compared to the untreated group. Histological and ultrastructural changes in the midgut tissues of treated and untreated beetles were also observed. The current findings provide a precedent for describing the physiological and histological changes caused by NiO-NPs in the ground beetle B. polychresta.

A Synergistic New Approach Toward Enhanced Antibacterial Efficacy via Antimicrobial Peptide Immobilization on a Nitric Oxide-Releasing Surface

Despite technological advancement, nosocomial infections are prevalent due to the rise of antibiotic resistance. A combinatorial approach with multimechanistic antibacterial activity is desired for an effective antibacterial medical device surface strategy. In this study, an antimicrobial peptide, nisin, is immobilized onto biomimetic nitric oxide (NO)-releasing medical-grade silicone rubber (SR) via mussel-inspired polydopamine (PDA) as a bonding agent to reduce the risk of infection. Immobilization of nisin on NO-releasing SR (SR-SNAP-Nisin) and the surface characteristics were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy with energy-dispersive X-ray spectroscopy and contact angle measurements. The NO release profile (7 days) and diffusion of SNAP from SR-SNAP-Nisin were quantified using chemiluminescence-based nitric oxide analyzers and UV-vis spectroscopy, respectively. Nisin quantification showed a greater affinity of nisin immobilization toward SNAP-doped SR. Matrix-assisted laser desorption/ionization mass spectrometry analysis on surface nisin leaching for 120 h under physiological conditions demonstrated the stability of nisin immobilization on PDA coatings. SR-SNAP-Nisin shows versatile in vitro anti-infection efficacy against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus in the planktonic and adhered states. Furthermore, the combination of NO and nisin has a superior ability to impair biofilm formation on polymer surfaces. SR-SNAP-Nisin leachates did not elicit cytotoxicity toward mouse fibroblast cells and human umbilical vein endothelial cells, indicating the biocompatibility of the material in vitro. The preventative and therapeutic potential of SR-SNAP-Nisin dictated by two bioactive agents may offer a promising antibacterial surface strategy.

Stability Evaluation of Lyotropic Liquid Crystalline Precursor for the Co-delivery of Chlorhexidine and Silver Nanoparticles

Sealing the therapeutic agents in the root canal is considered to be an essential step in root canal therapy. The lyotropic liquid crystalline precursor (LLCP) incorporated with chlorhexidine (CHX) and silver nanoparticles (Ag-NPs) has been confirmed as a promising candidate for root canal therapy in the previous study. Importantly, the stability of the LLCP system was a significant determinant for its therapeutic effect and further application. The objective of this study was to comprehensively investigate the stability of the LLCP incorporated with CHX and Ag-NPs. The oil-water partition coefficient of CHX and Ag-NPs was measured. The water absorption and the physical stability of drug-loaded LLCP solution were studied. Stability under high temperature, high humidity, and strong light irradiation was also investigated. The results demonstrated that CHX and Ag-NPs could be entrapped in the water channel of LLCP, indicating the low tendency of drugs leakage. The drug-loaded LLCP was a pseudoplastic fluid and it showed an excellent physical stability with a sedimentation rate of 0.981 and a settling time of 26~28 h. The payload of LLCP was confirmed to weaken the water absorption behavior, which facilitated its transformation to cubic liquid crystal. The stress testing under high temperature, high humidity, and strong light irradiation also manifested that the LLCP was stable when stored under moisture-proof condition. In conclusion, the developed LLCP incorporated with CHX and Ag-NPs was highly stable during storage and qualified for further application.

Green Synthesized Metal Oxide Nanoparticles Mediate Growth Regulation and Physiology of Crop Plants under Drought Stress

Metal oxide nanoparticles (MONPs) are regarded as critical tools for overcoming ongoing and prospective crop productivity challenges. MONPs with distinct physiochemical characteristics boost crop production and resistance to abiotic stresses such as drought. They have recently been used to improve plant growth, physiology, and yield of a variety of crops grown in drought-stressed settings. Additionally, they mitigate drought-induced reactive oxygen species (ROS) through the aggregation of osmolytes, which results in enhanced osmotic adaptation and crop water balance. These roles of MONPs are based on their physicochemical and biological features, foliar application method, and the applied MONPs concentrations. In this review, we focused on three important metal oxide nanoparticles that are widely used in agriculture: titanium dioxide (TiO2), zinc oxide (ZnO), and iron oxide (Fe3O4). The impacts of various MONPs forms, features, and dosages on plant growth and development under drought stress are summarized and discussed. Overall, this review will contribute to our present understanding of MONPs' effects on plants in alleviating drought stress in crop plants.

Evaluation of Long-Lasting Antibacterial Properties and Cytotoxic Behavior of Functionalized Silver-Nanocellulose Composite

Materials possessing long-term antibacterial behavior and high cytotoxicity are of extreme interest in several applications, from biomedical devices to food packaging. Furthermore, for the safeguard of the human health and the environment, it is also stringent keeping in mind the need to gather good functional performances with the development of ecofriendly materials and processes. In this study, we propose a green fabrication method for the synthesis of silver nanoparticles supported on oxidized nanocellulose (ONCs), acting as both template and reducing agent. The complete structural and morphological characterization shows that well-dispersed and crystalline Ag nanoparticles of about 10-20 nm were obtained in the cellulose matrix. The antibacterial properties of Ag-nanocomposites (Ag-ONCs) were evaluated through specific Agar diffusion tests against E. coli bacteria, and the results clearly demonstrate that Ag-ONCs possess high long-lasting antibacterial behavior, retained up to 85% growth bacteria inhibition, even after 30 days of incubation. Finally, cell viability assays reveal that Ag-ONCs show a significant cytotoxicity in mouse embryonic fibroblasts.

Bacterial metal nanoparticles to develop new weapons against bacterial biofilms and infections

The widespread use of antibiotics has resulted in the outbreak and spread of antibiotic-resistant pathogens. Bacterial antibiotic resistance may develop at cellular and community levels. In the latter case, it is based on tolerance which implicates the shift from a free-living form of life (i.e., planktonic) to a sessile multi-stratified community (i.e., biofilm). Metal nanoparticles (MNPs) have been shown to be promising candidates as antimicrobial agents. MNPs are able to interact with and penetrate bacterial biofilms, thus, resulting effective antibiofilm compounds. Another interesting aspect is the possibility of using plants, fungi, yeasts, and bacteria to obtain biogenic MNPs (BMNP). Bacteria are able to grow in presence of many different toxic heavy metal ions thanks to different metal resistance gene clusters that allow a variety of biochemical counters (formation of harmless complexes, efflux, precipitation, reduction, etc.). The formation of BMNPs by bacterial cells could be, in most cases, just a consequence of metal detoxification mechanisms. This review focuses on BMNPs from bacterial origin that may represent a good source of compounds with a broad spectrum of activity against common Gram-positive and Gram-negative pathogens and bacterial biofilms thereof. In particular, the state of art on BMNP synthesis by bacteria is presented and potential applications in the fight against biofilm-associated infections and resistant pathogens are highlighted. In addition, critical aspects on BMNP bacterial synthesis and utilization are commented.Key points• New antimicrobials to fight antibiotic-resistant pathogens are urgently needed.• Biogenic metal nanoparticles can efficiently hit biofilm-forming pathogens.• Metal-nanoparticle composition could confer specific antibiofilm activity.

Assessment of combining biosynthesized silver nanoparticles using Bacillus thuringiensis and gamma irradiation for controlling Pectinophora gossypiella (saunders) (lepidoptera: Gelechiidae)

PURPOSE

Combining gamma irradiation and nanotechnology has become one of the most promising new approaches for area-wide (AW) pest management in recent years. The laboratory trials were conducted to determine the combining effects of BT-AgNPs and gamma irradiation for controlling P. gossypiella. Radio-sensitivity of male pupae at different doses of gamma radiation and the effectiveness of biosynthesized silver nanoparticles using Bacillus thuringiensis on larval instar were assayed. Additionally, the ultrastructure changes on the alimentary canal of 4th instar larvae were studied to evaluate the impact of the combined approach at a cellular level.

MATERIALS AND METHODS

Laboratory- rearing technique was used for rearing Pectinophora gossypiella. The irradiation process was achieved at Co60 - Gamma Chamber (4000 A). Alanine dosimeters were used for measuring the average absorbed dose and dose mapping. Preparation of Silver nanoparticles (AgNPs) using Bacillus thuringiensis (Bt) and their characterization has been investigated. The treated 4th instar larvae by gamma irradiation or ∕and BT-AgNPs were dissected under the stereo microscope. The alimentary canal was obtained anatomically and Transmission Electron Microscope) was used in examining the stained sections.

RESULTS

Based on the nonhatching eggs produced by irradiated males' pupae, the values of effective doses were calculated. The effective doses ranged from 16 to 291 Gy for the ED25 - ED75. The sterility index reached 74.1% when irradiated with males by 291 Gy crossed with nonirradiated females and the adult emergence decreased to be 35.3%. The insecticidal potential of Bt-AgNPs on the 2nd and 4th larval instars was dose-dependent and its LC50 toxicity value was 0. 3 and 0. 4 mg/ml, respectively. The lethal concentration LC50 of the 2nd instar larvae increased the larval and pupal mortality to 55% and 44.4%, respectively, and reduced the adult emergence to be 55.6%. The combining effects of Bt-AgNPs with 291 Gy induced 100% pupae mortality and there was no adult emergence in F1 generation. Such effects also severed the ultrastructure deformity of the midgut of the 4th instar larvae after the two-day post-treatment.

CONCLUSIONS

The combining effects are recommended as an effective IPM program to control P. gossypiella by releasing sterile males (derived from pupae irradiated with 291 Gy) crossing with the normal females in the field, and reducing the fertility of the population to 31.2%. Subsequently, the resulted larvae treated with LC50 of Bt-AgNPs prevented the adult emergence and stopped the life cycle of P. gossypiella.

Antibacterial effect of silver nanoparticles mixed with calcium hydroxide or chlorhexidine on multispecies biofilms

The purpose is to evaluate the antibacterial effects of the silver nanoparticles (AgNPs) (Nanografi, METU Teknokent, Ankara, Turkey) mixed with calcium hydroxide (Ca(OH)₂) (Ultracal XS, Ultradent, St Louis, US) or chlorhexidine gel (CHX) (Gluco-Chex, Cerkamed, Stalowa Wola, Poland) against a multispecies biofilm, by confocal laser scanning microscopy (CLSM) and culture-based analysis. Dentine blocks were inoculated with Enterococcus faecalis, Streptococcus mutans, Lactobacillus acidophilus and Actinomyces naeslundii for 1 week. Infected dentine blocks were randomly divided into groups according to medication; saline solution (SS), Ca(OH)₂, Ca(OH)₂ + AgNP, 2%CHX gel and 2%CHX gel + AgNP and time of application: 1 and 7 days (all groups, n = 5). Bacterial samples were collected before and after medication to quantify the bacterial load. Biofilm elimination was quantitatively analyzed by Live/Dead BacLight Bacterial Viability staining and CLSM. The addition of AgNPs to Ca(OH)₂ increased the effectiveness of medicament in terms of bacterial reduction in both application times (1 and 7 days) (p < 0.05: ANOVA, Tukey's test) according to culture-based analysis. The CLSM images revealed that mixture of AgNP with CHX killed significantly more bacteria when compared with all other medicaments at 1- and 7-day application times (p < 0.05 and p > 0.05, respectively: Kruskal-Wallis, Dunn post hoc tests). The efficacy of Ca(OH)₂ mixed with AgNPs was superior to Ca(OH)₂ used alone in both application times (p < 0.05) according to CLSM analysis. The present study put forth the potential use of AgNPs mixed with Ca(OH)₂ or CHX on multispecies (Enterococcus faecalis, Streptococcus mutans, Lactobacillus acidophilus and Actinomyces naeslundii) biofilm in 1 and 7day application periods.

Cloth Face Masks Containing Silver: Evaluating the Status

Amid the coronavirus disease 2019 pandemic, demand for cloth face masks containing nanosilver has increased. Common product claims such as "antiviral" and "antimicrobial" can be attractive to buyers seeking to protect themselves from this respiratory disease, but it is important to note that filtration capabilities are the main factor to prevent virus transmission and that antimicrobial ability is a secondary protection factor. Silver has long been known to be antibacterial, and growing research supports additional antiviral properties. In this study, 40 masks claiming to contain silver were evaluated for substantiated antiviral and antimicrobial claims using methods available to the public. Criteria for determining the validity of substantiated claims included the use of patented technology, international certification for antimicrobial and/or antiviral textile by ISO or ASTM, EPA pesticide registration, and peer-reviewed literature. Our analysis showed that, of the 40 masks, 21 had substantiated claims. Using scanning electron microscopy (SEM), two of the substantiated face masks (A and B) were examined for silver identification for further confirmation. Mask A uses silver and copper ions attached to zeolite particles; the zeolite particles discovered through SEM were approximately 90-200 nm in diameter. In mask B, particles of silver and titanium at the 250 nm size were found. In conclusion, these certifications or patents are not enough to determine credibility, and stricter regulations by federal agencies on product testing for manufacturers that make claims are necessary to ensure the efficacy of the product advertised, as well as a cloth face mask inhalation standard.

Titanium Nanotube Modified With Silver Cross-Linked Basic Fibroblast Growth Factor Improves Osteoblastic Activities of Dental Pulp Stem Cells and Antibacterial Effect

Titanium modifications with different silver loading methods demonstrate excellent antibacterial properties. Yet pure silver nanoparticles with limited bioactive properties may delay regeneration of bone surrounding the dental implant. Therefore, loading silver with bioactive drugs on titanium surfaces seems to be a very promising strategy. Herein, we designed a silver (Ag) step-by-step cross-linking with the basic fibroblast growth factor (bFGF) by polydopamine (PDA) and heparin on titanium nanotube (TNT) as its cargo (TNT/PDA/Ag/bFGF) to improve the implant surface. Our results showed that TNT/PDA/Ag/bFGF significantly enhanced the osteogenic differentiation of dental pulp stem cells (DPSCs). It also showed an excellent effect in bacterial inhibition and a reduction of pro-inflammatory factors through inhibition of M1 macrophage activity. These results showed that bFGF cross-linked silver coating on TNTs presented good osteogenic differentiation and early anti-infiammatory and antibacterial properties. Together, this novel design on titanium provides a promising therapeutic for dental implants.

SARS-CoV-2: phylogenetic origins, pathogenesis, modes of transmission, and the potential role of nanotechnology

The COVID-19 pandemic has elicited a rapid response from the scientific community with significant advances in understanding the causative pathogen (SARS-CoV-2). Mechanisms of viral transmission and pathogenesis, as well as structural and genomic details, have been reported, which are essential in guiding containment, treatment, and vaccine development efforts. Here, we present a concise review of the recent research in these domains and an exhaustive analysis of the genomic origins of SARS-CoV-2. Particular emphasis has been placed on the pathology and disease progression of COVID-19 as documented by recent clinical studies, in addition to the characteristic immune responses involved therein. Furthermore, we explore the potential of nanomaterials and nanotechnology to develop diagnostic tools, drug delivery systems, and personal protective equipment design within the ongoing pandemic context. We present this as a ready resource for researchers to gain succinct, up-to-date insights on SARS-CoV-2.

Synthesis, Characterization, Antibacterial and Wound Healing Efficacy of Silver Nanoparticles From Azadirachta indica

Bacteria are the causative agents of numerous diseases. Ever increasing number of bacterial infections has generated the need to find new antibiotic materials and new ways to combat bacterial infections. Our study investigated Azadirachta indica (AI) as an alternate source of antibiotic compounds. Phytochemical and GC-MS analysis revealed presence of flavonoids, phenolic compounds, terpenoids and terpenes. Aqueous extracts of leaves were used to synthesize silver nanoparticles (AI-AgNPs), as established by colorimetric confirmation with maximum absorbance peak at 400 nm. Optimized reaction parameters produced high yield of stable AI-AgNPs, which were characterized by UV-Vis spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and transmission electron microscopy. Results confirmed particle diameter of 33 nm and spherical shape of AI-AgNPs. Fourier transform infrared spectroscopy inferred the presence of functional groups in bioactive constituents involved in conversion of silver ions into elemental silver by acting as capping and reducing agents during formation of AI-AgNPs. X-ray diffraction revealed their crystalline nature. Toxicity studies on Drosophila validated normal egg laying capacity and eclosion of F1 generation on AI-AgNPs (100 μg/mL). DPPH (65.17%) and ABTS (66.20%) assays affirmed strong radical scavenging effect of AI-AgNPs (500 μg/mL). The antibacterial activity of AI-AgNPs (1,000 μg/mL) was confirmed by disc diffusion assay with zone of inhibition against Bacillus cereus (17.7 mm), Escherichia coli (18.7 mm), Pseudomonas aeruginosa (10.3 mm), and Staphylococcus aureus (17.7 mm). Minimum inhibitory concentration and minimum bactericidal concentration values for AI-AgNPs ranged between 390 and 780 μg/mL. Higher bacterial suppression by AI-AgNPs in comparison with AI-extract was further divulged by prominent damage to the bacterial cell walls, disintegration of cell membranes and outflow of intercellular content as evident in SEM images. AI-AgNPs were loaded on PF127 (biocompatible-biodegradable polymer) to form a viscous, spreadable, hydrogel that demonstrated enhanced antibacterial properties in disc diffusion assay (13-18.7 mm). When topically applied on mice, AI-AgNPs-PF127 hydrogel did not show symptoms of skin irritation. Application of AI-AgNPs-PF127 hydrogel on wound sites in mice, significantly increased the wound contraction rate. Our studies present a simple green route to synthesize AI-AgNPs with enhanced antibacterial and free-radical scavenging efficacy; and AI-AgNPs-PF127 hydrogel as a low-toxic, eco-friendly delivery vehicle with potential in wound healing.

Nanotechnology for virus treatment

The continued emergence of novel viruses poses a significant threat to global health. Uncontrolled outbreaks can result in pandemics that have the potential to overburden our healthcare and economic systems. While vaccination is a conventional modality that can be employed to promote herd immunity, antiviral vaccines can only be applied prophylactically and do little to help patients who have already contracted viral infections. During the early stages of a disease outbreak when vaccines are unavailable, therapeutic antiviral drugs can be used as a stopgap solution. However, these treatments do not always work against emerging viral strains and can be accompanied by adverse effects that sometimes outweigh the benefits. Nanotechnology has the potential to overcome many of the challenges facing current antiviral therapies. For example, nanodelivery vehicles can be employed to drastically improve the pharmacokinetic profile of antiviral drugs while reducing their systemic toxicity. Other unique nanomaterials can be leveraged for their virucidal or virus-neutralizing properties. In this review, we discuss recent developments in antiviral nanotherapeutics and provide a perspective on the application of nanotechnology to the SARS-CoV-2 outbreak and future virus pandemics.

Architectured Therapeutic and Diagnostic Nanoplatforms for Combating SARS-CoV-2: Role of Inorganic, Organic, and Radioactive Materials

Although extensive research is being done to combat SARS-CoV-2, we are yet far away from a robust conclusion or strategy. With an increased amount of vaccine research, nanotechnology has found its way into vaccine technology. Researchers have explored the use of various nanostructures for delivering the vaccines for enhanced efficacy. Apart from acting as delivery platforms, multiple studies have shown the application of inorganic nanoparticles in suppressing the growth as well as transmission of the virus. The present review gives a detailed description of various inorganic nanomaterials which are being explored for combating SARS-CoV-2 along with their role in suppressing the transmission of the virus either through air or by contact with inanimate surfaces. The review further discusses the use of nanoparticles for development of an antiviral coating that may decrease adhesion of SARS-CoV-2. A separate section has been included describing the role of nanostructures in biosensing and diagnosis of SARS-CoV-2. The role of nanotechnology in providing an alternative therapeutic platform along with the role of radionuclides in SARS-CoV-2 has been described briefly. Based on ongoing research and commercialization of this nanoplatform for a viral disease, the nanomaterials show the potential in therapy, biosensing, and diagnosis of SARS-CoV-2.

Antifungal Activity of Gelatin-Tapioca Starch Film and Coating Containing Copper Nanoparticles against Colletotrichum gloeosporioides Causing Anthracnose

This study aimed to fabricate a nontoxic coating containing copper nanoparticles (CuNPs) to protect fruits from pathogenic Colletotrichum gloeosporioides causing anthracnose on several tropical fruits. We used a green approach, in which CuNPs were synthesized by reducing CuSO4 with ascorbic acid in the presence of gelatin and glycerol as the capping agents. The formation of CuNPs was confirmed by UV-vis absorption spectra of the reaction mixture, which showed a surface plasmon resonance peak at 578–594 nm. The x-ray diffraction spectrum of the CuNPs indicated the presence of mostly metallic copper with some minor impurities of Cu2O, CuO, and Cu(OH)2. Transmission electron microscopy (TEM) images and dynamic light scattering studies showed that the sizes of 90% of CuNPs were in 100–300 nm range. A 30–50 nm capping layer of gelatin surrounding CuNPs can be observed in the TEM images. Comparing FTIR spectra of the used reagents and CuNPs confirmed the depletion of ascorbic acid, as well as the gelatin layer protecting CuNPs. The synthesized CuNPs showed dose-dependent antifungal activity against C. gloeosporioides with 100% growth inhibition at 200 ppm copper. Gelatinized tapioca starch was then added to the CuNPs solution to obtain a film-forming mixture to produce stand-alone composite films on Petri dishes and coatings on mangoes. C. gloeosporioides could not grow on the surface of nutrient agar in contact with the films containing 245 ppm CuNPs, while they grew normally on control films without CuNPs. For the in vivo antifungal tests on mangoes, both the control and the CuNPs-containing coatings equally inhibit fungal growth, possibly due to the low oxygen permeability of the protein and starch components in the films. This study thus demonstrated the potential applications of composite coatings using biodegradable polymers that contain CuNPs in postharvest protecting fruits from phytopathogenic fungi.

The tale of a versatile enzyme: Molecular insights into keratinase for its industrial dissemination

Keratinases are unique among proteolytic enzymes for their ability to degrade recalcitrant insoluble proteins, and they are of critical importance in keratin waste management. Over the past few decades, researchers have focused on discovering keratinase producers, as well as producing and characterizing keratinases. The application potential of keratinases has been investigated in the feed, fertilizer, leathering, detergent, cosmetic, and medical industries. However, the commercial availability of keratinases is still limited due to poor productivity and properties, such as thermostability, storage stability and resistance to organic reagents. Advances in molecular biotechnology have provided powerful tools for enhancing the production and functional properties of keratinase. This critical review systematically summarizes the application potential of keratinase, and in particular certain newly discovered catalytic capabilities. Furthermore, we provide comprehensive insight into mechanistic and molecular aspects of keratinases including analysis of gene sequences and protein structures. In addition, development and current advances in protein engineering of keratinases are summarized and discussed, revealing that the engineering of protein domains such as signal peptides and pro-peptides has become an important strategy to increase production of keratinases. Finally, prospects for further development are also proposed, indicating that advanced protein engineering technologies will lead to improved and additional commercial keratinases for various industrial applications.

Relative expression of microRNAs, apoptosis, and ultrastructure anomalies induced by gold nanoparticles in Trachyderma hispida (Coleoptera: Tenebrionidae)

The extensive use of nanomaterials generates toxic effects on non-target species and the ecosystem. Although gold nanoparticles (Au-NPs) are generally expected to be safe, the recent study contains conflicting data regarding their cytotoxicity in the darkling beetles Trachyderma hispida. The study postulated cellular perturbation in the ovarian tissue of the beetles induced by a sublethal dose of Au-NPs (0.01 mg/g). When compared with the controls, a significant inhibition in the activities of the antioxidant enzymes selenium-dependent (GPOX) and selenium-independent (GSTP) glutathione peroxidases (GPx) was observed in the treated beetles. The study proposed microRNAs (miRNA-282 and miRNA-989) as genotoxic markers for the first time, reporting a significant suppression in their transcriptional levels in the treated beetles. Furthermore, TUNEL (Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) and flow cytometry assays (annexin V-Fitc) indicated a significant increase in ovarian cell apoptosis in the treated beetles. Additionally, an ultrastructure examination revealed pathological changes in the ovarian cells of the treated beetles. The resulting anomalies in the present study may interrupt the fecundity of the beetles and lead to the future suppression of beetle populations.

Sustainable One-Step Solid-State Synthesis of Antibacterially Active Silver Nanoparticles Using Mechanochemistry

A combination of solid-state mechanochemical and green approaches for the synthesis of silver nanoparticles (AgNPs) is explored in this study. Thymus serpyllum L. (SER), Sambucus nigra L. (SAM) and Thymus vulgaris L. (TYM) plants were successfully applied to reduce AgNO3 to AgNPs, as confirmed by X-ray diffraction analysis, with SER being the best reducing agent, and TYM being the worst. The experiments were performed via a one-step planetary milling process, where various AgNO3:plant mass ratios (1:1, 1:10, 1:50 and 1:100) were investigated. Atomic absorption spectrometry indicated that the stability of the mechanochemically produced AgNPs increased markedly when a sufficiently large quantity of the reducing plant was used. Furthermore, when larger quantities of plant material were employed, the crystallite size of the AgNPs decreased. TEM analysis revealed that all AgNPs produced from both AgNO3:plant ratios 1:1 and 1:10 exhibit the bimodal size distribution with the larger fraction with size in tens of nm and the smaller one below 10 nm in size. The antibacterial activity of the produced AgNPs was observed only for AgNO3:plant ratio 1:1, with the AgNPs prepared using SER showing the greatest antibacterial properties.

Synthesis of Functional Silver Nanoparticles and Microparticles with Modifiers and Evaluation of Their Antimicrobial, Anticancer, and Antioxidant Activity

An accumulating body of evidence reports the synthesis and biomedical applications of silver nanoparticles. However, the studies regarding the use of maleic acid and citric acid in the synthesis of nano-sized silver particles (AgNPs) and micro-sized silver particles (AgMPs) as well as their antibacterial, antifungal, and anticancer activities have not been reported. In the current study, we synthesized AgNPs and AgMPs using maleic acid and citric acid as capping agents and have characterized them by UV-Vis, energy-dispersive X-Ray spectroscopy (EDS), X-Ray diffraction (XRD), and scanning electron microscope (SEM) analysis. The capped silver particles were examined for their antimicrobial activity and cytotoxicity against bacteria, fungi, and brine shrimp. Additionally, the anticancer activity of these particles was tested against human breast and liver cancer cell lines. The free radical scavenging activity of capped silver particles was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. SEM analysis revealed a round plate-like morphology of maleic acid capped particles with an average size of 39 ± 4 nm, whereas citric acid capped particles display flower-shaped morphology with rough surfaces and an average size of 250 ± 5 nm. The uncapped AgMPs were hexagonal with 500 ± 4 nm size. EDS and XRD analysis confirmed the presence of Ag and face-centered cubic crystalline nature, respectively. Functionally, capped silver particles exhibited antibacterial activity against Gram-positive (Staphylococcus aureus, Bacillus subtilis, and Micrococcus luteus) and Gram-negative bacteria (Salmonella setubal, Enterobacter aerogenes, and Agrobacterium tumefaciens). The bactericidal activity was more active against Gram-negative bacteria with minimum inhibitory concentration (MIC) as low as 5 ppm as compared to 25 ppm for Gram-positive. Similarly, the silver particles demonstrated antifungal activity by inhibiting the growth of five fungal strains (Mucor species, Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus, and Fusarium solani) up to 50% at the concentration of 500 ppm. Additionally, these particles showed substantial toxicity against brine shrimp and also significantly inhibited the proliferation of breast cancer (MCF7) and liver cancer (HePG2) cell lines (IC₅₀ 8.9-18.56 µM). Uncapped AgMPs were less effective, inhibiting only the proliferation of MCF7 cells with IC₅₀ 46.54 µM. Besides cytotoxicity, these particles acted as potential antioxidants, showing free radical scavenging up to 74.4% in a concentration-dependent manner. Taken together, our results showed that the modifiers affect the shape and size of silver particles and may, in part, contribute to the antimicrobial and antioxidant activity of silver particles. However, the contribution of maleic acid and citric acid in enhancing the antimicrobial, anticancer, and antioxidant potential independent of silver nano and microparticles needs to be studied further. In vivo experiments may determine the therapeutic effectiveness of silver particles capped with these modifiers.

Ecotoxicity Evaluation of Pristine and Indolicidin-coated Silver Nanoparticles in Aquatic and Terrestrial Ecosystem

BACKGROUND

Metallic nanoparticles (NPs) are highly exploited in manufacturing and medical processes in a broad spectrum of industrial applications and in the academic sectors. Several studies have suggested that many metallic nanomaterials including those derived by silver (Ag) are entering the ecosystem to cause significant toxic consequences in cell culture and animal models. However, ecotoxicity studies are still receiving limited attention when designing functionalized and non.-functionalized AgNPs.

OBJECTIVE

This study aimed to investigate different ecotoxicological profiles of AgNPs, which were analyzed in two different states: in pristine form uncoated AgNPs and coated AgNPs with the antimicrobial peptide indolicidin. These two types of AgNPs are exploited for a set of different tests using Daphnia magna and Raphidocelis subcapitata, which are representatives of two different levels of the aquatic trophic chain, and seeds of Lepidium sativum, Cucumis sativus and Lactuca sativa.

RESULTS

Ecotoxicological studies showed that the most sensitive organism to AgNPs was crustacean D. magna, followed by R. subcapitata and plant seeds, while AgNPs coated with indolicidin (IndAgNPs) showed a dose-dependent decreased toxicity for all three.

CONCLUSION

The obtained results demonstrate that high ecotoxicity induced by AgNPs is strongly dependent on the surface chemistry, thus the presence of the antimicrobial peptide. This finding opens new avenues to design and fabricate the next generation of metallic nanoparticles to ensure the biosafety and risk of using engineered nanoparticles in consumer products.

Mycosynthesis of Silver Nanoparticles Using Screened Trichoderma Isolates and Their Antifungal Activity against Sclerotinia sclerotiorum

To control the disease caused by Sclerotinia sclerotiorum, a total of 15 isolates of the Trichoderma species was screened for the biosynthesis of silver nanoparticles (AgNPs). Among them, the highest yield occurred in the synthesis of AgNPs using a cell-free aqueous filtrate of T.virens HZA14 producing gliotoxin. The synthetic AgNPs were charactered by SEM, EDS, TEM, XRD, and FTIR. Electron microscopy studies revealed that the size of AgNPs ranged from 5–50 nm and had spherical and oval shapes with smooth surfaces. Prepared AgNPs interacted with protein, carbohydrate and heterocyclic compound molecules, and especially, interaction patterns of AgNPs with the gliotoxin molecule were proposed. The antifungal activity assays demonstrated that percentage inhibition of the prepared AgNPs was 100, 93.8 and 100% against hyphal growth, sclerotial formation, and myceliogenic germination of sclerotia at a concentration of 200 μg/mL, respectively. The direct interaction between nanoparticles and fungal cells, including AgNPs’ contact, accumulation, lamellar fragment production and micropore or fissure formation on fungal cell walls, was revealed by SEM and EDS. These will extend our understanding of the mechanisms of AgNPs’ action for preventing diversified fungal disease.

Development and evaluation of a novel beneficent antimicrobial bioscaffold based on animal waste-fish swim bladder (FSB) doped with silver nanoparticles

Treated fish wastes have found many applications in industry and medicine. Besides, nowadays low-cost scaffold with antimicrobial activity which can accelerates the process of wound healing is very demanding. In this study fish swim bladder (FSB), taken from Rutilus frisii, which is a disposable waste was doped with silver nanoparticles (AgNPs) and evaluated as antimicrobial wound dressing. The scanning electron microscopy (SEM) micrographs showed the presence of AgNPs on the scaffold. Histological observation confirmed cells and muscle removal from FSB and collagen preservation. There was significant antibacterial activity even in 50 ppm AgNPs concentration against pathogenic bacteria, swelling ratio was rather low, and cytotoxic assay revealed that the AgNPs-FSB scaffold had no toxic effect on human foreskin fibroblast (HFF) cells. Interestingly, despite the porous structure, the AgNPs-FSB scaffold was found to be a suitable barrier to microbial penetration even after 72 h. Further study showed the gradual release of AgNPs during 24 h. In conclusion, biofabricated FSB prepared in this study have appropriate characteristics notably encompassing a high quantity of collagen and broad-spectrum antimicrobial activity. Also, its porous structure made it suitable as a 3-D structure for the growth of cells and adding other antimicrobial nano-sized materials.

Eco-friendly synthesis of silver nanoparticles from the whole plant of Cleome viscosa and evaluation of their characterization, antibacterial, antioxidant and antidiabetic properties

The current research is to develop an easy and eco-friendly method for the synthesis of three different concentrations of silver nanoparticles (1mMCvAgNPs, 2mMCvAgNPs and 3mMCvAgNPs) using aqueous whole plant extract of Cleome viscosa and to evaluate their antibacterial, antioxidant and antidiabetic properties. CvAgNPs were characterized by Using UV–vis spectrophotometer, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and transmission electron microscope (TEM). The formation of CvAgNPs was confirmed by the observation of band between 250 nm to 600 nm UV–vis spectrum. The crystalline structure of CvAgNPs with a face-centered cubic (FCC) was confirmed by XRD. The responsible phytochemicals for the reduction and capping material of CvAgNPs were observed with FT-IR. The SEM analysis confirmed the size and shapes of CvAgNPs. The CvAgNPs have shown the rich content of total phenolic and total flavonoid components. The CvAgNPs have shown significant antibacterial activity on multi drug resistance Gram-negative and Gram-positive bacteria and also have shown significant strong antioxidant activities (DPPH, ABTS, H₂O₂ scavenging, Phosphomolybdenum assay and reducing power). The inhibitory action of CvAgNPs on α-glucosidase and α-amylase was stronger than the inhibitory action of acarbose. To best of our knowledge, this is the first attempt on the synthesis of AgNPs using C. viscosa whole plant aqueous extract. The synthesized CvAgNPs exhibited good antimicrobial, antioxidant and antidiabetic properties. Hence, to validate our results, the in vivo studies at the molecular level are needed to develop Cleome viscosa as an antibacterial, antioxidant and anti-diabetic agent.

TRAIL-conjugated silver nanoparticles sensitize glioblastoma cells to TRAIL by regulating CHK1 in the DNA repair pathway

OBJECTIVES

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) selectively triggers apoptosis in cancer cells, but not in normal cells. Resistance of glioblastoma cells to TRAIL is a major obstacle for successful clinical treatment of TRAIL. Thus, there is an essential requirement for novel approaches to sensitize TRAIL resistance. Silver nanoparticles (AgNPs) are one of the most promising nanomaterials that show immense antitumor potential via targeting various cellular and molecular processes; however, the effects of AgNPs on TRAIL sensitivity in cancer cells remain unclear. Therefore, we hypothesized that TRAIL-conjugated AgNPs (TRAIL-AgNPs) can overcome TRAIL resistance through inducing death receptor activation in glioblastoma cells, but not normal cells.

METHODS

In this study, the therapeutic effect of TRAIL-AgNPs is investigated by analyzing the cell viability, caspase activity, and CHK1 gene expression in T98 G TRAIL-Sensitive (TS) and T98 G TRAIL-Resistant (TR) glioblastoma cells.

RESULTS

It is found that TRAIL-AgNPs are more toxic compared to TRAIL and AgNPs treatments alone on TR cells. While TRAIL and AgNPs alone do not enhance the caspase activity, conjugation of TRAIL to AgNPs increases the caspase activity in TR cells. Moreover, the TRAIL-AgNPs-treated TR cells show less CHK1 expression compared to the TRAIL treatment.

CONCLUSION

These results suggest that TRAIL sensitivity of TR cells can be enhanced by conjugation of TRAIL with AgNPs, which would be a novel therapeutic approach to sensitize TRAIL resistance.

Eco Friendly Approach for Synthesis, Characterization and Biological Activities of Milk Protein Stabilized Silver Nanoparticles

Today, the overall occurrence of re-emerging and rising illnesses has been a serious load on economies as well as public health. Here, we describe a simple, nontoxic and eco-friendly method for the synthesis of milk protein (MP)-stabilized silver nanoparticles (MP-s-AgNPs) using ultrahigh-temperature full cream milk. Highly stable AgNPs were prepared with a fair control over their size, without using any reducing or stabilizing agent, and their formation was attributed to the presence of the MP casein. Ag⁺ ion reduction was possibly caused by the MPs. The synthesized MP-s-AgNPs were characterized in detail by ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and dynamic light scattering. MP-s-AgNPs showed inhibitory activity against both Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative microorganisms (Salmonella typhi and Escherichia coli). Moreover, MP-s-AgNPs were found to be more toxic to bacteria than to fungi (Aspergillus fumigatus, Aspergillus ochraceus and Penicillium chrysogenum).

Development of Robust Chitosan–Silica Class II Hybrid Coatings with Antimicrobial Properties for Titanium Implants

The purpose of this study was to develop robust class II organic–inorganic films as antibacterial coatings on titanium alloy (Ti6Al4V) implants. Coating materials were prepared from organic chitosan (20–80 wt.%) coupled by 3-glycydoxytrimethoxysilane (GPTMS) with inorganic tetraethoxysilane (TEOS). These hybrid networks were imbedded with antimicrobial silver nanoparticles (AgNPs) and coated onto polished and acid-etched Ti6Al4V substrates. Magic-angle spinning nuclear magnetic resonance (13CMAS-NMR), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) and the ninhydrin assay, confirmed the presence and degree of covalent crosslinking (91%) between chitosan and GPTMS. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) identified surface roughness and microtopography on thin films and confirmed homogeneous distribution of elements throughout the coating. Cross-hatch and tensile adhesion testing demonstrated the robustness and adherence (15–20 MPa) of hybrid coatings to acid-etched titanium substrates. Staphylococcus aureus and Escherichia coli cultures and their biofilm formation were inhibited by all hybrid coatings. Antibacterial effects increased markedly for coatings loaded with AgNPs and appeared to increase with chitosan content in biofilm assays. These results are promising in the development of class II hybrid materials as robust and highly adherent antibacterial films on Ti6Al4V implants.

Silver nanoparticles: Toxicity in model organisms as an overview of its hazard for human health and the environment

Silver nanoparticles (AgNPs) have attracted remarkable attention due to their powerful antimicrobial action as well as their particular physicochemical properties. This has led to their application in a wide variety of products with promising results. However, their interaction with the environment and toxicity in live terrestrial or aquatic organisms is still a matter of intense debate. More detailed knowledge is still required about the toxicity of AgNPs, their possible uptake mechanisms and their adverse effects in live organisms. Several studies have reported the interactions and potential negative effects of AgNPs in different organisms. In this review, we report and discuss the current state of the art and perspectives for the impact of AgNPs on different organisms present in the environment. Recent progress in interpreting uptake, translocation and accumulation mechanisms in different organisms and/or living animals are discussed, as well as the toxicity of AgNPs and possible tolerance mechanisms in live organisms to cope with their deleterious effects. Finally, we discuss the challenges of accurate physicochemical characterization of AgNPs and their ecotoxicity in environmentally realistic conditions such as soil and water media.

Surface modification approaches for prevention of implant associated infections

In this highlight, we summarize the surface modification approaches for development of infection-resistant coatings for biomedical devices and implants. We discuss the relevant key and highly cited research that have been published over the last five years which report the generation of infection-resistant coatings. An important strategy utilized to prevent bacterial adhesion and biofilm formation on device/implant surface is anti-adhesive protein repellant polymeric coatings based on polymer brushes or highly hydrated hydrogel networks. Further, the attachment of antimicrobial agents that can efficiently kill bacteria on the surface while also prevent bacterial adhesion on the surface is also investigated. Other approaches include the incorporation of antimicrobial agents to the surface coating resulting in a depot of bactericides which can be released on-demand or with time to prevent bacterial colonization on the surface that kill the adhered bacteria on the surface to make surface infection resistant.

Effects of Silver Nanoparticle from Dicoma anomala Sond. Root Extract on MCF-7 Cancer Cell Line and NF54 Parasite Strain: an In Vitro Study

Biogenic silver nanoparticles (AgNPs) continue captivating researchers in biomedicine field of research. Dicoma anomala Sond. plant, locally known as hloenya, hlonya, maagbossie, inyongwana, is widely recommended by South African traditional health practitioners (THPs) to treat against different health issues. The antiplasmodial effects of novel sesquiterpene molecules (C₃₀H₃₆O₇; MW: 509.25) isolated from D. anomala Sond. have been reported by us (Patent US 8,586,112 B2). The aim of the study was to determine the anticancer activity of AgNPs synthesized using D. anomala plant root extract and the antiparasitic potency of AgNP-conjugated sesquiterpene. Nanoparticles have been characterized using different methods. Anticancer activity of AgNPs was evaluated against the MCF-7. This study also revealed that the AgNP-conjugated sesquiterpene has shown better antiparasitic activity against Plasmodium falciparum NF54 strain. One-pot synthesized AgNPs using Dicoma anomala Sond. root extract caused oxidative damage in breast cancer cells. These findings indicate the need for more in-depth research in the use of the AgNPs and sesquiterpene for development into potential leads as an antimalarial candidates and to improve the bioavailability of these sesquiterpenes.

Adaptive changes induced by noble-metal nanostructures in vitro and in vivo

The unique features of noble-metal nanostructures (NMNs) are leading to unprecedented expansion of research and exploration of their application in therapeutics, diagnostics and bioimaging fields. With the ever-growing applications of NMNs, both therapeutic and environmental NMNs are likely to be exposed to tissues and organs, requiring careful studies towards their biological effects in vitro and in vivo. Upon NMNs exposure, tissues and cells may undergo a series of adaptive changes both in morphology and function. At the cellular level, the accumulation of NMNs in various subcellular organelles including lysosomes, endoplasmic reticulum, Golgi apparatus, mitochondria, and nucleus may interfere with their functions, causing changes in a variety of cellular functions, such as digestion, protein synthesis and secretion, energy metabolism, mitochondrial respiration, and proliferation. In animals, retention of NMNs in metabolic-, respiratory-, immune-related, and other organs can trigger significant physiological and pathological changes to these organs and influence their functions. Exploring how NMNs interact with tissues and cells and the underlying mechanisms are of vital importance for their future applications. Here, we illustrate the characteristics of NMNs-induced adaptive changes both in vitro and in vivo. Potential strategies in the design of NMNs are also discussed to take advantage of beneficial adaptive changes and avoid unfavorable changes for the proper implementation of these nanoplatforms.

Development of Non-ionic Surfactant and Protein-Coated Ultrasmall Silver Nanoparticles: Increased Viscoelasticity Enables Potency in Biological Applications

To enhance the interactivity with biological cells, we developed ultrasmall (5 nm in diameter) Ag NPs coated with a mixture of Tween-20 (Tw-20) surfactant and human serum albumin (HSA) or hemoglobin (Hb) proteins. These were tested with cancerous and healthy cell lines to investigate the therapeutic applicability. Using the established concept of generation of reactive oxygen species (ROS) and the ROS-induced oxidative stress in carcinogenic cells by Ag NPs, we found that the presently synthesized Ag NPs selectively destroyed the cancerous cells. A mixture of Tw-20 with protein, where the surfactant was in large excess, created a coating over the Ag NPs resulting weaker protein-protein interactions and facilitating interfacial protein-surfactant interactions, which leads to an increase in the film viscoelasticity to enhance the stability of the Ag NPs and cell viability. Moreover, this concept has been applied to drug delivery using a model fluorophore (fluorescein) on Ag NPs to explore the prospects in photodynamic therapy. The results are encouraging and deserve further investigation.