Biogenic silver nanoparticles: assessment of their cytotoxicity, genotoxicity and study of capping proteins

The development of nanotechnology in the last two decades has led to the use of silver nanoparticles (AgNPs) in various biomedical applications, including antimicrobial, anti-inflammatory, and anticancer therapies. However, the potential of the medical application of AgNPs depends on the safety of their use. In this work, we assessed the in vitro cytotoxicity and genotoxicity of silver nanoparticles and identified biomolecules covering AgNPs synthesized from actinobacterial strain SH11. The cytotoxicity of AgNPs against MCF-7 human breast cancer cell line and murine macrophage cell line RAW 264.7 was studied by MTT assay, cell LDH (lactate dehydrogenase) release, and the measurement of ROS (reactive oxygen species) level while genotoxicity in Salmonella typhimurium cells was testing using the Ames test. The in vitro analysis showed that the tested nanoparticles demonstrated dose-dependent cytotoxicity against RAW264.6 macrophages and MCF-7 breast cancer cells. Moreover, biosynthesizedAgNPsdid not show a mutagenic e ect of S. typhimurium. The analyses and identification of biomolecules present on the surface of silver nanoparticles showed that they were associated with proteins. The SDS-PAGE (sodium dodecyl sulfate–polyacrylamide gel electrophoresis) analysis revealed the presence of 34 and 43 kDa protein bands. The identification of proteins performed by using LC-MS/MS (liquid chromatography with tandem mass spectrometry) demonstrated their highest homology to bacterial porins. Capping biomolecules of natural origin may be involved in the synthesis process of AgNPs or may be responsible for their stabilization. Moreover, the presence of natural proteins on the surface of bionanoparticles eliminates the postproduction steps of capping which is necessary for chemical synthesis to obtain the stable nanostructures required for application in medicine

Streptomyces alkaliterrae sp. nov., isolated from an alkaline soil, and emended descriptions of Streptomyces alkaliphilus, Streptomyces calidiresistens and Streptomyces durbertensis

A polyphasic study was undertaken to establish the taxonomic position of six representative streptomycetes isolated from an alkaline soil adjacent to a meteoric alkaline soda lake in India. Chemotaxonomic, cultural and morphological properties of the isolates were consistent with their classification in the genus Streptomyces. The isolates formed extensively branched substrate mycelia and aerial hyphae that differentiated in straight chains of spores with smooth surfaces. They contained LL-diaminopimelic acid in the wall peptidoglycan, produced either hexa- or octa-hydrogenated menaquinones with nine isoprene units, major amounts of saturated, iso- and anteiso- fatty acids and phosphatidylethanolamine as the characteristic polar lipid. The isolates grew well at 30 °C, pH 9 and in the presence of 3 to 5% (w/v) sodium chloride. Isolates OF1T, OF3 and OF8 formed a distinct clade within the Streptomyces 16S rRNA gene tree sharing relatively high sequence similarities with the type strains of Streptomyces durbertensis (99.3%), Streptomyces palmae (98.1%) and Streptomyces xinghaiensis (98.3%), but can be distinguished from them using combinations of phenotypic properties. A phylogenomic tree based on draft genome sequences of the isolates and S. durbertensis DSM 104538T confirmed the phylogenetic relationships. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values calculated from the whole genome sequences of isolate OF1T and S. durbertensis DSM 104538T were low at 92.0% and 45.2%, respectively, indicating that they belong to different genomic species. Consequently, on the basis of the genomic, phylogenetic and associated phenotypic data it is proposed that isolates OF1T, OF3 and OF8 be assigned to the genus Streptomyces as Streptomyces alkaliterrae sp. nov. with strain OF1T (NCIMB 15195T =PCM 3001T) as the type strain. Isolates IF11, IF17 and IF19, and S. alkaliphilus DSM 42118T were shown to belong to the same taxospecies and together with S. calidiresistens DSM 42108T comprised a well supported clade in the Streptomyces 16S rRNA gene tree. Isolate IF17 and S. alkaliphilus DSM 42118T formed a well-supported clade in the phylogenomic tree, had almost identical digital G + C similarity values, produced long straight chains of smooth-surfaced spores and shared ANI and dDDH values (98.0 and 79.6%, respectively) consistent with their assignment to the same genomic species. In light of all of the data isolates IF11, IF17 and IF19 should be seen as authentic stains of S. alkalihilus. Data acquired in the present study have also been used to emend the descriptions of S. alkaliphilus, S. calidiresistens and S. durbertensis. The genomes of isolates IF17, and OF1T, OF3 and OF8 contain relatively high numbers of biosynthetic gene clusters some of which were discontinously distributed indicating ones predicted to express for novel specialised metabolites

Biofabrication of novel silver and zinc oxide nanoparticles from Fusarium solani IOR 825 and their potential application in agriculture as biocontrol agents of phytopathogens, and seed germination and seedling growth promoters

Introduction: Plant pathogenic microorganisms adversely affect the growth and yield of crops, which consequently leads to losses in food production. Metal-based nanoparticles (MNPs) can be a remedy to solve this problem.Methods: Novel silver nanoparticles (AgNPs) and zinc oxide nanoparticles (ZnONPs) were biosynthesized from Fusarium solani IOR 825 and characterized using Dynamic Light Scattering (DLS), Fourier Transform Infrared (FTIR) spectroscopy, Transmission Electron Microscopy (TEM), X-ray diffraction (XRD) and measurement of Zeta potential. Antibacterial activity of NPs was evaluated against four plant pathogenic strains by determination of the minimum inhibitory (MIC) and biocidal concentrations (MBC). Micro-broth dilution method and poisoned food technique were used to assess antifungal activity of NPs against a set of plant pathogens. Effect of nanopriming with both types of MNPs on maize seed germination and seedlings growth was evaluated at a concentration range of 1–256 μg mL-1.Results: Mycosynthesis of MNPs provided small (8.27 nm), spherical and stable (zeta potential of −17.08 mV) AgNPs with good crystallinity. Similarly, ZnONPs synthesized by using two different methods (ZnONPs(1) and ZnONPs(2)) were larger in size (117.79 and 175.12 nm, respectively) with Zeta potential at −9.39 and −21.81 mV, respectively. The FTIR spectra showed the functional groups (hydroxyl, amino, and carboxyl) of the capping molecules on the surface of MNPs. The values of MIC and MBC of AgNPs against bacteria ranged from 8 to 256 μg mL-1 and from 512 to 1024 μg mL-1, respectively. Both types of ZnONPs displayed antibacterial activity at 256–1024 μg mL-1 (MIC) and 512–2048 μg mL-1 (MBC), but in the concentration range tested, they revealed no activity against Pectobacterium carotovorum. Moreover, AgNPs and ZnONPs inhibited the mycelial growth of Alternaria alternata, Fusarium culmorum, Fusarium oxysporum, Phoma lingam, and Sclerotinia sclerotiorum. MIC and MFC values of AgNPs ranged from 16–128 and 16–2048 μg mL -1, respectively. ZnONPs showed antifungal activity with MIC and MFC values of 128–2048 μg mL-1 and 256–2048 μg mL-1, respectively. The AgNPs at a concentration of ≥32 μg mL-1 revealed sterilization effect on maize seeds while ZnONPs demonstrated stimulatory effect on seedlings growth at concentrations of ≥16 μg mL-1 by improving the fresh and dry biomass production by 24% and 18%–19%, respectively.Discussion: AgNPs and ZnONPs mycosynthesized from F. solani IOR 825 could be applied in agriculture to prevent the spread of pathogens. However, further toxicity assays should be performed before field evaluation. In view of the potential of ZnONPs to stimulate plant growth, they could be crucial in increasing crop production from the perspective of current food assurance problems

Biogenic silver nanoparticles: What we know and what do we need to know?

Nanobiotechnology is considered to be one of the fastest emerging fields. It is still a relatively new and exciting area of research with considerable potential for development. Among the inorganic nanomaterials, biogenically synthesized silver nanoparticles (bio-AgNPs) have been frequently used due to their unique physicochemical properties that result not only from their shape and size but also from surface coatings of natural origin. These properties determine antibacterial, antifungal, antiprotozoal, anticancer, anti-inflammatory, and many more activities of bio-AgNPs. This review provides the current state of knowledge on the methods and mechanisms of biogenic synthesis of silver nanoparticles as well as their potential applications in different fields such as medicine, food, agriculture, and industries.Web of Science1111art. no. 290

Pullulan-based films impregnated with silver nanoparticles from the Fusarium culmorum strain JTW1 for potential applications in the food industry and medicine

Introduction: Biopolymers, such as pullulan, a natural exopolysaccharide from Aureobasidium pullulans, and their nanocomposites are commonly used in the food, pharmaceutical, and medical industries due to their unique physical and chemical properties. Methods: Pullulan was synthesized by the A. pullulans ATCC 201253 strain. Nanocomposite films based on biosynthesized pullulan were prepared and loaded with different concentrations of silver nanoparticles (AgNPs) synthesized by the Fusarium culmorum strain JTW1. AgNPs were characterized by transmission electron microscopy, Zeta potential measurements, and Fourier-transform infrared spectroscopy. In turn, the produced films were subjected to physico-chemical analyses such as goniometry, UV shielding capacity, attenuated total reflection–Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy, and their mechanical and degradation properties were assessed. The antibacterial assays of the nanoparticles and the nanocomposite films against both food-borne and reference pathogens, including Listeria monocytogenes, Salmonella infantis, Salmonella enterica, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae, were performed using standard methods. Results: AgNPs were small (mean 15.1 nm), spherical, and displayed good stability, being coated with protein biomolecules. When used in higher concentrations as an additive to pullulan films, they resulted in reduced hydrophilicity and light transmission for both UV-B and UV-A lights. Moreover, the produced films exhibited a smooth surface. Therefore, it can be concluded that the addition of biogenic AgNPs did not change the morphology and texture of the films compared to the control film. The nanoparticles and nanocomposite films demonstrated remarkable antibacterial activity against both food-borne and reference bacteria. The highest activity of the prepared films was observed against L. monocytogenes. Discussion: The obtained results suggest that the novel nanocomposite films prepared from biosynthesized pullulan and AgNPs can be considered for use in the development of medical products and food packaging. Moreover, this is the first report on pullulan-based nanocomposites with mycogenic AgNPs for such applications

Materials based on chitosan enriched with zinc nanoparticles for potential applications on the skin

Chitosan as a nontoxic, biodegradable, and biocompatible biopolymer with film-forming properties can also be modified to improve its parameters. Modification of polymer films by the addition of nanoparticles is an increasingly common solution due to the higher efficiency of products at the nanoscale compared to the macroscale. In this work, thin chitosan films enriched with biogenic zinc oxide nanoparticles (ZnONPs) from Fusarium solani IOR 825 were obtained by the solvent evaporation method. The influence of nanoadditive on the physicochemical, mechanical, and antimicrobial properties of the polymeric matrix was evaluated. Two different concentrations of ZnONPs were added to the chitosan solution. Spectrometric measurements, mechanical tests, microscopic imaging, and microbiological tests were performed for nanoparticlesmodified and control samples. Analysis revealed that ZnONPs influence the properties of chitosan films. FTIR spectroscopy showed changes that are the result of interactions between polymer matrix and the additive. Modified samples were characterized by increased values of Young’s modulus and tensile strength. SEM analysis combined with energy-dispersive X-ray spectrometry confirmed the presence of zinc in the modified films. The addition of nanoparticles slightly affected the surface morphology of the tested samples, and an increase in roughness was observed. Microbiological tests showed the biostatic activity of the films containing ZnONPs. The obtained films based on chitosan with the addition of ZnONPs can be considered easy-to-obtain biomaterials with potential use as cosmetic and biomedical products

Silver nanoparticles, synthesis and biological activity.

Rosnąca oporność bakterii, zwłaszcza rosnących w biofilmach, na konwencjonalne antybiotyki jest przyczyną szerokich poszukiwań nowych środków terapeutycznych. Nanocząstki srebra, ze względu na udowodniony potencjał antybakteryjny, są intensywnie badane. Istnieje kilka metod syntezy nanosrebra, najbardziej przyjazna dla środowiska jest synteza biogeniczna. Nanocząstki srebra charakteryzują się mnogością wewnątrzkomórkowych celów działania. Mechanizm ich antybakteryjnej aktywności opiera się głównie na uszkodzeniu osłon bakteryjnych i indukcji reaktywnych form tlenu. Nanocząstki srebra, oprócz dużego potencjału antybakteryjnego, zdolne są do współdziałania z konwencjonalnymi antybiotykami, w ten sposób potęgowana jest ich aktywność. Wiele badań in vitro i in vivo wskazuje na toksyczność nanosrebra wobec Eukaryota, obiecujący jest zwłaszcza ich potencjał anty-nowotworowy. Powszechne użycie nanocząstek wymusza konieczność rygorystycznego monitoringu ich syntezy i stosowania.The growing resistance of bacteria, especially those living in biofilms, to conventional antibiotics causes a broad search for new therapeutic agents. Silver nanoparticles, due to their known antibacterial activity, are intensively studied. Among several methods of nanosilver synthesis, the most friendly is the biogenic "green" synthesis. The targets and mechanisms of action of silver nanoparticles are pleiotrophic, and involve mainly destruction of cellular envelopes and induction of reactive oxygen species. Nanosilver particles are also able to interact with conventional antibiotics, thus enhancing their antibacterial activity. The data obtained both in vivo and in vitro demonstrate the toxic effect of nanosilver on Eukaryota, including its antitumor potential. The broad usage of silver nanoparticles calls for a restricted monitoring of their production and application

“To Be Microbiocidal and Not to Be Cytotoxic at the Same Time…”—Silver Nanoparticles and Their Main Role on the Surface of Titanium Alloy Implants

The chemical vapor deposition (CVD) method has been used to produce dispersed silver nanoparticles (AgNPs) on the surface of titanium alloy (Ti6Al4V) and nanotubular modified titanium alloys (Ti6Al4V/TNT5), leading to the formation of Ti6Al4V/AgNPs and Ti6Al4V/TNT5/AgNPs systems with different contents of metallic silver particles. Their surface morphology and silver particles arrangement were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), and atomic force microscopy (AFM). The wettability and surface free energy of these materials were investigated on the basis of contact angle measurements. The degree of silver ion release from the surface of the studied systems immersed in phosphate buffered saline solution (PBS) was estimated using inductively coupled plasma ionization mass spectrometry (ICP-MS). The biocompatibility of the analyzed materials was estimated based on the fibroblasts and osteoblasts adhesion and proliferation, while their microbiocidal properties were determined against Gram-positive and Gram-negative bacteria, and yeasts. The results of our works proved the high antimicrobial activity and biocompatibility of all the studied systems. Among them, Ti6Al4V/TNT5/0.6AgNPs contained the lowest amount of AgNPs, but still revealed optimal biointegration properties and high biocidal properties. This is the biomaterial that possesses the desired biological properties, in which the potential toxicity is minimized by minimizing the number of silver nanoparticles