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The antimicrobial impact of biogenic-synthesized silver-based nanoparticles has been the focus of increasing interest. As the antimicrobial activity of nanoparticles is highly dependent on their size and surface, the complete and adequate characterization of the nanoparticle is important. This review discusses the characterization and antimicrobial activity of biogenic synthesized silver nanoparticles and silver chloride nanoparticles. By revising the literature, there is confusion in the characterization of these two silver-based nanoparticles, which consequently affects the conclusion regarding to their antimicrobial activities. This review critically analyzes recent publications on the synthesis of biogenic silver nanoparticles and silver chloride nanoparticles by attempting to correlate the characterization of the nanoparticles with their antimicrobial activity. It was difficult to correlate the size of biogenic nanoparticles with their antimicrobial activity, since different techniques are employed for the characterization. Biogenic synthesized silver-based nanoparticles are not completely characterized, particularly the nature of capped proteins covering the nanomaterials. Moreover, the antimicrobial activity of theses nanoparticles is assayed by using different protocols and strains, which difficult the comparison among the published papers. It is important to select some bacteria as standards, by following international foundations (Pharmaceutical Microbiology Manual) and use the minimal inhibitory concentration by broth microdilution assays from Clinical and Laboratory Standards Institute, which is the most common assay used in antibiotic ones. Therefore, we conclude that to have relevant results on antimicrobial effects of biogenic silver-based nanoparticles, it is necessary to have a complete and adequate characterization of these nanostructures, followed by standard methodology in microbiology protocols.

Aqueous extract of Neolamarchia cadamba leaves were used in the synthesis of silver/silver chloride nanoparticles (Ag/AgCl NPs). Further they were separated based on their using step-wise centrifugation approach at 09,000, 12,000, and 15,000 rpm. Thus obtained NPs were characterized for their physicochemical features. NPs showed maximum absorbance at 455 nm, 415 nm, and 402 nm. All the NPs were found to be crystalline in nature with average crystallite size (nm) of 58.31, 23.43, and 09.56. Particle size distribution (nm) of NPs was observed to 435.43, 276.75, and 105.49, Surface charge (-mV) of NPs was observed to be 14.59, 23.90, and 32.17. Ag/AgCl NPs-rpm@15,000 showed antibacterial activity against Escherichia coli , coagulase-negative Staphylococci, and Staphylococcus aureus with zone of inhibition (mm) of 16.65, 13.69, and 14.02 at 50 µg per well, respectively. Ag/AgCl NPs-rpm@15,000 showed excellent catalytic activity in degradation of methyl red, methylene blue, rhodamine-B, and methyl orange dyes in the presence of sodium borohydride under 4, 6, 5, and 4 min with pseudo-first order rate constant (min −1 ) of 0.981 (96.4%), 0.666 (97.1%), 0.905 (98.1%), and 1.032 (96.6%), respectively. Furthermore, Ag/AgCl NPs-rpm@15,000 showed good catalytic efficiency even under different dye combinations. Total combination was degraded under 18 min. Graphical Abstract

The phyto-development of nanomaterials is one of the main challenges for scientists today, as it offers unusual properties and multifunctionality. The originality of our paper lies in the study of new materials based on biomimicking lipid bilayers loaded with chlorophyll, chitosan, and turmeric-generated nano-silver/silver chloride particles. These materials showed a good free radical scavenging capacity between 76.25 and 93.26% (in vitro tested through chemiluminescence method) and a good antimicrobial activity against Enterococcus faecalis bacterium (IZ > 10 mm). The anticancer activity of our developed bio-based materials was investigated against two cancer cell lines (human colorectal adenocarcinoma cells HT-29, and human liver carcinoma cells HepG2) and compared to one healthy cell line (human fibroblast BJ cell line). Cell viability was evaluated for all prepared materials after a 24 h treatment and was used to select the biohybrid with the highest therapeutic index (TI); additionally, the hemolytic activity of the samples was also evaluated. Finally, we investigated the morphological changes induced by the developed materials against the cell lines studied. Biophysical studies on these materials were done by correlating UV–Vis and FTIR absorption spectroscopy, with XRD, SANS, and SAXS methods, and with information provided by microscopic techniques (AFM, SEM/EDS). In conclusion, these “green” developed hybrid systems are an important alternative in cancer treatment, and against health problems associated with drug-resistant infections.

Currently, there is unprecedented emergence of antimicrobial resistant (AMR) bacteria which demand urgent development of novel strategies to combat bacterial infections in humans. In this study, we report on a facile and eco-friendly green synthesis of silver-silver chloride nanoparticles (Ag/AgCl-NPs) using macadamia (Macadamia integrifolia) nutshell (MNS) agro-waste. The effects of physicochemical parameters including pH, Ag ion precursor concentration, time, and temperature were investigated. The biosynthesized Ag/AgCl-NPs sample was characterized using ultraviolet visible spectroscopy (UV–Vis), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) spectroscopy, field emission scanning spectroscopy (FE-SEM), Transmission electron microscopy (TEM), and energy dispersive X-ray (EDX). UV–Vis spectroscopy exhibited surface plasmon resonance (SPR) between 420 and 446 nm typical for silver nanoparticles (AgNPs). FT-IR spectroscopy provided an insight of the phytochemicals responsible for the reduction of Ag+ into Ago and capping/stabilizing the formed Ag/AgCl-NPs. XRD spectroscopy revealed the formation of crystalline Ag/AgCl-NPs with characteristic peaks at around 38.3°, 44.1°, 64.6°, and 77.5° for AgNPs, and 28.9°, 31.9°, 45.4°, 56.3°, and 66.1° for AgCl NPs. FE-SEM spectroscopy exhibited spherical and block like morphologies of agglomerated Ag/AgCl-NPs. TEM illustrated polydisperse spherical shapes of Ag/AgCl-NPs with average particle sizes of 31.11 nm. EDX confirmed the presence of Ag and Cl elements confirming the formation of Ag/AgCl-NPs. The antibacterial activity of the green synthesized Ag/AgCl-NPs was performed using disc diffusion method and the zone inhibition (ZOI) evaluation showed their effectiveness against Gram negative (E. coli) and Gram positive (S. aureus).

The role of silver–silver chloride electrode for providing the reference potential is quite important for the precise potentiometric measurements. Our study focuses to find the conditions for its optimal use, especially, in perspective for a long-term viability of electrode. In particular, we reassessed the temporal stability of the standard potential and presented the results of its measurement for a time span of ten years.

In this study, very simple and fast one-step synthesis of biogenic silver chloride nanoparticles (AgCl-NPs) using a Pulicaria vulgaris Gaertn. aerial part extract from an aqueous solution of silver nitrate at room temperature is proposed. The proceedings of the reaction were investigated by UV–Vis spectroscopy. AgCl-NPs were characterized using X-ray diffraction spectroscopy (XRD), Fourier-transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). Antibacterial and antifungal activities of these nanoparticles were evaluated by disk diffusion and microdilution methods against Staphylococcus aureus, Escherichia coli, Candida albicans, and C. glabrata. In addition, the antioxidant activity of the synthesized AgCl-NPs was determined by the DPPH radical scavenging assay. The antimicrobial test confirmed the bactericidal activity of biosynthesized AgCl-NPs against Gram-positive and Gram-negative bacteria. They also exhibited good antifungal activities with minimum inhibitory concentration (MIC) values ranging from 40 to 60 µg/mL against Candida glabrata and Candida albicans, respectively. In addition, biosynthesized AgCl-NPs were established to have remarkable antioxidant activity. All this pointed out that the proposed new biosynthesis approach resulted in production of AgCl-NPs with convenient biomedical applications.

Silver chloride nanoparticles and microplastics are polluting in surface waters, yet their interactions, associated toxicity and environmental risks are poorly known. Here we hypothesized that polystyrene microplastics could enhance the phototransformation of silver chloride nanoparticles and modify their toxicity. We conducted phototransformation of silver chloride nanoparticles with polystyrene microplastics under light irradiation. The photo-dissolution of silver chloride nanoparticles and photo-reduction of silver ions were determined in both double-distilled-water and environmental waters. We found that polystyrene microplastics highly enhanced the phototransformation of silver chloride nanoparticles by hydroxyl radicals, singlet oxygen, and triplet state microplastics, leading to the release of silver ions and chloride ions. Subsequently, the silver ions were reduced to silver nanoparticles by superoxide radicals. Consequently, the silver species transformation increased the toxicity of silver chloride nanoparticles even at environmental concentration, as evidenced by survival rate of zebrafish larvae reduced from 100% to 23.3%. This is the first study to show that polystyrene microplastics can enhance the phototransformation of silver chloride nanoparticles to silver nanoparticles, thereby increasing the environmental risks of silver chloride nanoparticles in environmental waters.

The biological methods are considered as environmental-eco-friendly methods for the silver nanocomposites mediation and are widely used in this context. However, the biological methods go along with the relevant limitations, for instance simultaneous synthesis of silver chlorides (AgNCl) type during the AgNPs mediation process. Therefore, the present research is coming to summarize several aspects in this context. Firstly, to present the possible promotion of the sustainable development using bioactive source (e.g. milk) as a source of two different available and new lactobacillus strains (Lactobacillus curvatus and Lactobacillus fermentum). Secondly, to show the ability of the respective isolates to be involved in mediation of various biosilver nanocomposites ((Bio)NCs) synthesis. Moreover, at this stage, for the first time, two (Bio)NCs mediation methods, called “direct method” and “modified method”, have been developed, thus three types (AgNPs, AgNCl and AgNP@AgNCl) of nanocomposites mediated by two different Lactobacillus isolates take place. The interdisciplinary approach included using several spectroscopic, microscopic, spectrometric and thermogravimetric methods demonstrated that all six synthesized nanoparticles (three AgNPs, AgNCl and AgNP@AgNCl types from each source) consist of complex structure including both metallic silver core as well as organic surface deposits. The spectrometric technique allowed to identification of the organics branching surface, naturally secreted by the used Lactobacillus isolates during the inoculation step, suggesting the presence of amino-acids sequences which are direct connected with the reduction of silver ion to metal silver, and subsequently with the formation of coated (Bio)NCs and nucleation process. Moreover, based on the obtained results, the mediation mechanism of each (Bio)NCs has been proposed, suggesting that the formation of AgNPs, AgNCl and AgNP@AgNCl types occurs in different manners with faster synthesis firstly of AgNCl, then of the AgNPs type. No differences between the (Bio)NCs synthesized by two different Lactobacillus isolates have been noticed indicating no discrepancies between metabolites secreted by the respective sources. Graphical abstract

Silver chloride nanoparticles (AgClNps) were biosynthesized extracellularly by Flavobacterium panacis (DCY106 T ), which was isolated from the rhizosphere of Panax ginseng in Gochang, Republic of Korea. The reduction of silver nitrate by DCY106 T was initiated within 24 h at 37 °C. The complete reaction did not require supplemental reducing or stabilizing agents, further demonstrating the facile and simple synthesis of this methodology. The formation of nanoparticles was confirmed by UV–Vis spectroscopy, showing the maximum absorbance at ~ 402 nm. Field emission transmission electron microscopy revealed a spherical structure of the nanoparticles. Furthermore, the average size of AgClNps was around 20.66 nm as determined by X-ray diffraction. Fourier transform infrared spectroscopy analysis showed that functional biomolecules, such as proteins or enzymes from the cell-free supernatant of DCY106 T , may provide nanoparticle stabilization against aggregations. In addition, the biosynthesized AgClNps served as competent antimicrobial agents against several pathogenic bacteria and fungi. Antioxidant results determined by 2, 2-diphenyl-1-picrylhydrzyl (DPPH) scavenging assay exhibited an efficient antioxidant activity of AgClNps. Moreover, AgClNps also revealed the anticancer potential against human lung cancer cells. Thus, this study proposes a facile extracellular synthesis of AgClNps by F. panacis (DCY106 T ) are applicable as the potential antimicrobial, antioxidant, and anticancer agents.

In this study, characterization and anticancer activity of synthesized silver and silver chloride nanoparticles (Ag–AgCl NPs) using aqueous fruit extract of Levisticum Officinale were investigated. The first sign of the synthesis of Ag–AgCl NPs was the color change of the solution from yellow to brown due to the addition of plant extract to the silver nitrate (AgNO 3 ) solution, which was confirmed by UV–Vis spectroscopy. The phase and chemical characteristics, size, spherical shape, nanocrystalline structure and stability of Ag–AgCl NPs were evaluated by fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray analysis (EDX), transmission electron microscope (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), X-Ray diffraction (XRD) and zeta potential analyzes. The results confirmed the formation of spherical nanoparticles with the face centered cubic (FCC) crystalline structure. The cytotoxic effect of Ag–AgCl on MDA-MB-468 cancer cell line was studied by 3-[4,5 dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) colorimetric method at 48 h. Also, MTT assay results prove promising that the Ag–AgCl NPs could be an agent of breast cancer treatment.