Biogenic synthesis of antimicrobial silver nanoparticles capped with l-cysteine

Soft surface-enhanced Raman scattering sensing platform based on an oil-in-water emulsion stabilized by silver nanoparticles

Pickering emulsions are excellent candidates for developing soft biosensors utilized for detecting native biomolecules such as peptides and proteins through the Surface-Enhanced Raman Spectroscopy (SERS) transduction mechanism. Here, we have developed a SERS sensor based on oil-in-water Pickering emulsions stabilized by Ag nanoparticles (Ag-NPs) with the Raman active molecule (4-Aminothiphenol, 4ATP) adsorbed to their surface. The structural properties and composition of the Pickering emulsion were tuned to meet the demands of the maximal optical response. Our results show that the obtained SERS signals of the main studied Pickering emulsion (water: oil ratio 7:3, 1 wt% Ag-NPs) outperformed colloidal dispersions with the same Ag-NPs concentration by 10-fold at any studied content of 4ATP. The superior optical response of the Pickering emulsion compared to the colloidal dispersion can thus pave the way for the detection of a large variety of analytes at high sensitivity by a soft sensing device. This study innovates by comparing the SERS signals of Raman-active Ag-NPs when they are assembled at the oil/water interface of an emulsion to the case where the NPs are individually dispersed in the medium. The findings shed light on the edit value of utilizing Raman-active Pickering stabilizers for biosensing applications.

Green biologically synthesized metal nanoparticles: biological applications, optimizations and future prospects

In green biological synthesis, metal nanoparticles are produced by plants or microorganisms. Since it is ecologically friendly, economically viable and sustainable, this method is preferable to other traditional ones. For their continuous groundbreaking advancements and myriad physiochemical and biological benefits, nanotechnologies have influenced various aspects of scientific fields. Metal nanoparticles (MNPs) are the field anchor for their outstanding optical, electrical and chemical capabilities that outperform their regular-sized counterparts. This review discusses the most current biosynthesized metal nanoparticles synthesized by various organisms and their biological applications along with the key elements involved in MNP green synthesis. The review is displayed in a manner that will impart assertiveness, help the researchers to open questions, and highlight many points for conducting future research.

Structural, optical, morphological, sun-light driven photocatalytic and antimicrobial investigations of Ag2S and Cu/Ag2S nanoparticles

This study focusses on the preparation of silver sulphide (Ag2S) and Cu-doped Ag2S (Cu/Ag2S) nanoparticles (NPs) by sol-gel method and demonstrated their photocatalytic and antibacterial applications. The X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) analysis demonstrated that the prepared NPs are effectively crystallized in the polycrystalline single-phase monoclinic geometry of Ag2S. The optical bandgap is significantly reduced, and for both the sample the average grain size is observed to have narrowed from 42 nm to 23 nm. Both NPs were confirmed to be spherical nature as observed by scanning electron microscopy (SEM), and the energy dispersive X-ray (EDX) spectroscopy analysis validated the presence of all necessary components at the expected concentrations in the obtained samples. Under the irradiation of sunshine, the photocatalytic properties of each sample were investigated for their ability to facilitate the photodegradation of a hazardous methylene blue (MB) dye in an aqueous solution. Cu/Ag2S sample possesses a profound photocatalytic reaction for the destruction of MB dye. Furthermore, the Cu-doped Ag2S NPs suppress the proliferation of Staphylococcus aureus and Escherichia coli. In comparison to pure Ag2S NPs, Cu/Ag2S showed enhanced antibacterial activity against both the bacteria. Current study suggests that the Cu doped Ag2S NPs could be a promising material for wastewater treatment and antimicrobial agents.

In Situ and Ex Situ Raman Studies of Cysteine’s Behavior on a Titanium Surface in Buffer Solution

In this paper, surface-enhanced Raman spectroscopy (SERS) was used to investigate the adsorption process of cysteine (Cys). Studies were carried out in the presence of phosphate-buffered saline solution (PBS), at pH 7.4, and acidified to pH 5, 3, and 1, on the surface of Ti for implant application. In situ SERS spectra obtained for the Cys/Ti solution system, after 24 h of immersion time, indicated that the buffer solution strongly influences the adsorption behavior of Cys on the Ti surface. This results in a decrease in Cys adsorption on the Ti surface, in the range of pH 7.4 to 3. The strong interaction between a sulfur atom of Cys and a Ti surface was observed only at pH = 1, under strongly acidic conditions. In contrast, ex situ SERS spectra recorded for the same samples but in a dried Cys/Ti system show a completely different behavior of Cys on the Ti surface. Formation of a disulfide (S-S) bond has occurred as a result of the dimerization or aggregation of Cys molecules on the Ti surface. Detailed analysis of the adsorption behavior of Cys on the Ti surface can be very important in the preparation of bioactive materials (i.e., coated by organic layers).

A Novel Ag@AgCl Nanoparticle Synthesized by Arctic Marine Bacterium: Characterization, Activity and Mechanism

An additive- and pollution-free method for the preparation of biogenic silver and silver chloride nanoparticles (Ag@AgCl NPs) was developed from the bacteria Shewanella sp. Arc9-LZ, which was isolated from the deep sea of the Arctic Ocean. The optimal synthesizing conditions were explored, including light, pH, Ag⁺ concentration and time. The nanoparticles were studied by means of ultraviolet-visible (UV-Vis) spectrophotometry, energy dispersive spectrometry (EDS), X-ray diffraction (XRD) and inductively coupled plasma optical emission spectrometers (ICP-OES). The transmission electron microscope (TEM) showed that the nanoparticles were spherical and well dispersed, with particle sizes less than 20.00 nm. With Ag@AgCl nanoparticles, the kinetic rate constants for congo red (CR) and rhodamine B (RhB) dye degradation were 2.74 × 10^-1 min^-1 and 7.78 × 10^-1 min^-1, respectively. The maximum decolourization efficiencies of CR and RhB were 93.36% and 99.52%, respectively. Ag@AgCl nanoparticles also showed high antibacterial activities against the Gram-positive and Gram-negative bacteria. The Fourier transform infrared spectroscopy (FTIR) spectrum indicated that the O-H, N-H and -COO- groups in the supernatant of Arc9-LZ might participate in the reduction, stabilization and capping of nanoparticles. We mapped the schematic diagram on possible mechanisms for synthesizing Ag@AgCl NPs.

Interaction Mechanisms and Interface Configuration of Cysteine Adsorbed on Gold, Silver, and Copper Nanoparticles

Cysteine-protected metal nanoparticles (NPs) have shown interesting physicochemical properties of potential utility in biomedical applications and in the understanding of protein folding. Herein, cysteine interaction with gold, silver, and copper NPs is characterized by Raman spectroscopy and density functional theory calculations to elucidate the molecular conformation and adsorption sites for each metal. The experimental analysis of Raman spectra upon adsorption with respect to free cysteine indicates that while the C-S bond and carboxyl group are similarly affected by adsorption on the three metal NPs, the amino group is sterically influenced by the electronegativity of each metal, causing a greater modification in the case of gold NPs. A theoretical approach that takes into consideration intermolecular interactions using two cysteine molecules is proposed using a S-metal-S interface motif anchored to the metal surface. These interactions generate the stabilization of an organo-metallic complex that combines gauche (P_H) and anti (P_C) rotameric conformers of cysteine on the surface of all three metals. Similarities between the calculated Raman spectra and experimental data confirm the thiol and carboxyl as adsorption groups for gold, silver, and copper NPs and suggest the formation of monomeric "staple motifs" that have been found in the protecting monolayer of atomic-precise thiolate-capped metal nanoclusters.

Selenium Nanoparticles Biosynthesized by Pantoea agglomerans and Their Effects on Cellular and Physiological Parameters in the Rainbow Trout Oncorhynchus mykiss

Simple Summary

Nanoparticles (Nps), new biotechnological tools, possess unique physical and chemical properties and are increasingly being used in several fields, such as manufacture, medicine and veterinary medicine. In this work, we evaluated the effects of selenium (Se) nanoparticles stabilized with L-Cysteine (Se⁰Nps/L-Cys) as a nutritional supplement, to modulate immunological, oxidative status, and productive parameters in O. mykiss. The results demonstrated that Se⁰Nps/L-Cys showed less toxicity and higher antioxidant activity than Se⁰Nps and Na₂SeO₃. The Se⁰Nps/L-Cys, as a dietary supplement, had a significantly better effect on both immunological and physiological parameters, causing improvements at the productive level of O. mykiss when compared with Se⁰Nps and Na₂SeO₃. We concluded that Se⁰Nps sythetised by P. agglomerans, used as dietary supplement, is an environmentally friendly and promising alternative for nutritional supplementation for O. mykiss.

Abstract

The applications of nanoparticles (Nps) as food additives, health enhancers, and antimicrobials in animal production are increasing. The aim of this study was to evaluate the effect of selenium (Se) nanoparticles (Se⁰Nps) stabilized with L-cysteine (Se⁰Nps/L-Cys), as a nutritional supplement, on immunological, oxidative status, and productive parameters in O. mykiss. TEM and SEM-EDS showed the accumulation of spherical Se⁰Nps entirely composed by elemental selenium (Se⁰) as intracellular and extracellular deposits in Pantoea agglomerans UC-32 strain. The in vitro antioxidant capacity of Se⁰Nps/L-Cys was significant more efficient ROS scavengers than Se⁰Nps and Na₂SeO₃. We also evaluate the effect of Se⁰Nps/L-Cys on cell viability and oxidative stress in RTgill-W1, RTS-11, or T-PHKM Oncorhynchus mykiss cell lines. Se⁰Nps/L-Cys showed less toxic and high antioxidant activity than Se⁰Nps and Na₂SeO₃. Finally, the dietary Se⁰Nps/L-Cys had a significant better effect on both plasma lysozyme and respiratory burst activity (innate immune response), on tissular Gpx activity (oxidative status), and on well-being (productive parameter) of O. mykiss when it is compared to Se⁰Nps and Na₂SeO₃. Se⁰Nps/L-Cys is a promising alternative for nutritional supplement for O. mykiss with better performance than Na₂SeO₃ and Se⁰Nps, ease to implementation, and reduced environmental impact.

Multifarious Biological Applications and Toxic Hg2+ Sensing Potentiality of Biogenic Silver Nanoparticles Based on Securidaca inappendiculata Hassk Stem Extract

INTRODUCTION

The use of environmentally benign resources for nanoparticles synthesis is consistently pushed to the front burner in a bid to ensure and enhance environmental protection and beneficiation. In this light, application of different plant parts for the reduction and stabilization of nanoparticles is gaining popularity.

MATERIALS AND METHODS

In this contribution, we have exploited Securidaca inappendiculata stem extract (SISE), as the reducing and stabilizing agent for room temperature synthesis of highly stable and dispersed AgNPs. The major bioactive compounds in SISE were profiled using an ultra-high-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UHPLC-MS-QTOF-MS).

RESULTS AND DISCUSSION

SISE could reduce silver salts to its nanoparticles almost instantaneously with a maximum absorption spectrum at 423 nm, under the optimal conditions. The fabricated SISE AgNPs was extensively characterized using FTIR, TEM, SEM, XRD, EDS, Zeta analysis/DLS and TGA/DTG analysis. SISE AgNPs with average particles size between 10-15 nm and a zeta potential value of -19.5 ± 1.8 mV was obtained. It was investigated for in-vitro biological applications by carrying out, antimicrobial, antioxidant, hemolytic, cytotoxicity and antidiabetic assays. It was found that SISE AgNPs exhibited potent antimicrobial capacity against some food borne microbes, good antioxidant property, while also demonstrating high biocompatibility. Moreover, with a view to extending further the applications SISE AgNPs, it was tested as a colorimetric nanoprobe for Hg2+ detection in aqueous environment, where good linearity between 0.10 and 10.0 μM, with a detection limit of 26.5 nM, were obtained. The practicality of the probe was investigated by carrying out Hg2+ detection in water sample, with good accuracy and precision.

DISCUSSION

Overall, this work introduced a new stabilizer for biocompatible AgNPs with far-reaching applications.

Antibacterial and Antifungal Properties of Silver Nanoparticles-Effect of a Surface-Stabilizing Agent

The biocidal properties of silver nanoparticles (AgNPs) prepared with the use of biologically active compounds seem to be especially significant for biological and medical application. Therefore, the aim of this research was to determine and compare the antibacterial and fungicidal properties of fifteen types of AgNPs. The main hypothesis was that the biological activity of AgNPs characterized by comparable size distributions, shapes, and ion release profiles is dependent on the properties of stabilizing agent molecules adsorbed on their surfaces. Escherichia coli and Staphylococcus aureus were selected as models of two types of bacterial cells. Candida albicans was selected for the research as a representative type of eukaryotic microorganism. The conducted studies reveal that larger AgNPs can be more biocidal than smaller ones. It was found that positively charged arginine-stabilized AgNPs (ARGSBAgNPs) were the most biocidal among all studied nanoparticles. The strongest fungicidal properties were detected for negatively charged EGCGAgNPs obtained using (-)-epigallocatechin gallate (EGCG). It was concluded that, by applying a specific stabilizing agent, one can tune the selectivity of AgNP toxicity towards desired pathogens. It was established that E. coli was more sensitive to AgNP exposure than S. aureus regardless of AgNP size and surface properties.

Recent advances in anticancer and antimicrobial activity of silver nanoparticles synthesized using phytochemicals and organic polymers

Development of eco-friendly synthetic methods has resulted in the production of biocompatible Ag NPs for applications in medical sector. To overcome the prevailing antibiotic resistance in bacteria, Ag NPs are being extensively researched over the past few years due to their broad spectrum and robust antimicrobial properties. Silver nanoparticles are also being studied widely in advanced anticancer therapy as an alternative anticancer agent to combat cancer in an effective manner. Keeping this backdrop in consideration, this review aims to provide an extensive coverage of the recent progresses in the green synthesis of Ag NPs specifically using plant derived reducing agents such phytochemicals and numerous other biopolymers. Current development in antimicrobial activity of Ag NPs against various pathogens has been deliberated at length. Recent advances in potent anticancer activity of the biogenic Ag NPs against various cancerous cell lines has also been discussed in detail. Mechanistic details of the synthesis of Ag NPs, their anticancer and antimicrobial action has also been highlighted.

Self-assembly of silver nanoparticles through functionalization with coumarin-thiazole fused-ring thiol

Self-assembly of nanoscale building blocks plays a critical role for the edifice of functional nanomaterials. In this work coumarin based fused-ring heterocyclic thiol functionalized silver nanoparticle exhibiting large self-assembly is reported. The particles spontaneously self-organise towards the formation of larger superstructures, yet still retaining their individual particle morphology (~10nm). The π-stacking behaviour of coumarin based fused ring aromatic skeleton seems to play the key role for the induction of dense assembly in this hybrid nanoparticles. In the present work the anchoring group (thiol) is directly attached to the aromatic framework of the Coumarin-thiazole fused-ring, for easier electron flow between the metal and the aromatic ligand. The synthesized materials have been characterized by UV-Vis, Fluorescence, XRD, TEM, SAED, IR, 1H and 13C NMR. The synthesis of the ligand and process of functionalization is simple and easily reproducible.

Biosynthesis, characterization and antibacterial activity of silver nanoparticles by the Arctic anti-oxidative bacterium Paracoccus sp. Arc7-R13

Silver nanoparticles (AgNPs) have attracted wide interest due to its broad range of applications. This study aims to describe the biosynthesis of AgNPs using an Arctic anti-oxidative bacterium Arc7-R13 and to study its characteristics and antibacterial activity. The biosynthesis of AgNPs was verified using UV-Vis spectrum with the maximum absorption at 416 nm. The morphology of the silver nanoparticles was characterized by TEM and its characterization were investigated by EDX and FTIR. Phylogenetic analysis based on 16S rRNA gene sequence showed that strain Arc7-R13 was affiliated with genus Paracoccus. TEM analysis revealed that the AgNPs synthesized by strain Arc7-R13 were spherical and ellipsoidal in shape with size ranging from 2 to 25 nm. The optimal concentration of AgNO3 and temperature for the biosynthesis were 4 mmol/L and 37 °C, respectively. EDX analysis verified the presence of the element silver in the biosynthesized AgNPs. FTIR analysis revealed that the specific functional groups, OH, CH₃ and C≡N, might be responsible for reduction and stabilization of AgNPs. Antimicrobial test showed that the AgNPs had strong antimicrobial activity against all kinds of strains investigated, including Gram-positive Bacillus subtilis, Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa, Escherichia coli.

Recent advances in the application of silica nanostructures for highly improved water treatment: a review

The demand for high-quality safe and clean water supply has revolutionized water treatment technologies and become a most focused subject of environmental science. Water contamination generally marks the presence of numerous toxic and harmful substances. These contaminants such as heavy metals, organic and inorganic pollutants, oil wastes, and chemical dyes are discharged from various industrial effluents and domestic wastes. Among several water treatment technologies, the utilization of silica nanostructures has received considerable attention due to their stability, sustainability, and cost-effective properties. As such, this review outlines the latest innovative approaches for synthesis and application of silica nanostructures in water treatment, apart from exploring the gaps that limit their large-scale industrial application. In addition, future challenges for improved water remediation and water quality technologies are keenly discussed.

Microbially synthesized nanoparticles as next generation antimicrobials: scope and applications

The development of multidrug resistant (MDR) pathogens at an alarming rate has created a great health concern worldwide. Nanotechnology today provides hope as an alternative to antibiotics, in the field of antimicrobial therapy. The diverse structures and small size make the nanoparticles (NPs) exhibit unique and remarkable properties, drastically different from its bulk counterparts. Various microorganisms such as actinomycetes, algae, yeast, fungi, and bacteria synthesize inorganic nanoparticles enzymatically, either extracellularly or intracellularly. Various metallic NPs, for example, magnesium, titanium, copper, silver, and gold, are well reported for their antimicrobial, antiviral, and antifungal properties. The antimicrobial properties of these NPs may be attributed to its ability to disorganize membrane structure, form pores in the bacterial cell wall, inhibit or disruption biofilm, etc. Most metal oxide nanoparticles like ZnO-NPs, exhibit bactericidal properties by generating reactive oxygen species (ROS). However, other NPs like MgO-NPs are effective due to their peculiar physical structure. Nanoparticles can also be fabricated with various bioactive entities. Due to their small and controllable size, functionalized nanoparticles can deliver drugs precisely and safely to the target sites. Thus, microbial mediated production of nanoparticles is gaining substantial interest as a potential solution to the growing need for the development of eco-friendly ways to fight microbial resistance and control diseases.

Phytochemical-assisted synthetic approaches for silver nanoparticles antimicrobial applications: A review

Silver nanoparticles (Ag NPs) have recently emerged as promising materials in the biomedical sciences because of their antimicrobial activities towards a wide variety of microorganisms. Nanomaterial-based drug delivery systems with antimicrobial activity are critical as they may lead to novel treatments for cutaneous pathogens. In this review, we explore the recent progress on phytochemical-mediated synthesis of Ag NPs for antimicrobial treatment and associated infectious diseases. We discuss the biological activity of Ag NPs including mechanisms, antimicrobial activity, and antifungal/antiviral effects towards various microorganisms. The advent of Ag NP-based nanocarriers and nano-vehicles is also described for treatment of different diseases, along with the mechanisms of microbial inhibition. Overall, this review will provide a rational vision of the main achievements of Ag NPs as nanocarriers for inhibition of various microbial agents (bacteria, fungus, and virus).

Eco-friendly and cost-effective Ag nanocrystals fabricated using the leaf extract of Habenaria plantaginea: toxicity on six mosquito vectors and four non-target species

Recently, the biofabrication of metal nanoparticles has gained wide interest owing to its inherent features such as swift, simplicity, eco-friendliness, and cheaper costs. Different green-reducing agents led to the production of nanoparticles with varying toxicity on insects. In the current study, silver nanoparticles (AgNPs) were successfully synthesized using Habenaria plantaginea leaf extract. Ag nanoparticles were studied by UV-Vis spectroscopy (UV-Vis), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). H. plantaginea extract and AgNPs were tested for mosquito larvicidal activity on Anopheles stephensi, Aedes aegypti, Culex quinquefasciatus, An. subpictus, Ae. albopictus, and Cx. tritaeniorhynchus. LC₅₀ values were 102.51, 111.99, 123.47, 123.96, 136.56, 149.42 μg/ml and 12.23, 13.38, 14.78, 14.37, 15.39, 16.89 μg/ml, respectively. Moreover, H. plantaginea aqueous extract and AgNPs were tested against the non-target species Anisops bouvieri, Diplonychus indicus, Poecilia reticulata, and Gambusia affinis obtaining LC₅₀ values ranging from 831.82 to 36,212.67 μg/ml. Overall, this study showed the effectiveness of H. plantaginea-fabricated nanoparticles on a wide range of important mosquito vectors, highlighting their scarce toxicity on four natural enemies predating mosquito larvae and pupae.

Antibacterial properties of amino acid functionalized silver nanoparticles decorated on graphene oxide sheets

Graphene oxide (GO) sheets decorated with amino acid L-cysteine (L-cys) functionalized silver nanoparticles (GO-L-cys-Ag) was synthesized by AgNO₃, trisodium citrate, and NaBH₄. GO-L-cys-Ag nanocomposite was characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectra, ultraviolet-visible (UV-vis) absorption spectra, which demonstrated that a diameter of L-cys-AgNPs compactly deposited on GO. Antibacterial activity tests of GO-L-cys-Ag nanocomposite were carried out using Escherichia coli MTCC 1687 and Staphylococcus aureus MTCC 3160 as model strains of Gram-negative and Gram-positive bacteria, respectively. The effect of bactericide dosage on antibacterial activity of GO-L-cys-Ag nanocomposite was examined by plate count, well diffusion and broth dilution methods. Morphological observation of bacterial cells by scanning electron microscope (SEM) showed that GO-L-cys-Ag nanocomposite was more destructive to cell membrane of Escherichia coli than that of Staphylococcus aureus. The above technique establish that the bactericidal property of GO-L-cys-Ag nanocomposite with wide range of applications in biomedical science.

Thiourea functionalized β-cyclodextrin as green reducing and stabilizing agent for silver nanocomposites with enhanced antimicrobial and antioxidant properties

Rapid development of microbial resistance against traditional antibiotics has generated a need for the synthesis of new more potent, less toxic, target specific, cost effective and biodegradable antimicrobial agents.

Green synthesis and characterization of silver nanoparticles using Ferula latisecta leaf extract and their application as a catalyst for the safe and simple one-pot preparation of spirooxindoles in water

In this research, Ag nanoparticles were prepared via plant extract and applied as an efficient catalyst in a three component reaction for the synthesis of spirooxindols.

Silver nanoparticle based antibacterial methacrylate hydrogels potential for bone graft applications

Infections are frequent and very undesired occurrences after orthopedic procedures; furthermore, the growing concern caused by the rise in antibiotic resistance is progressively dwindling the efficacy of such drugs. Artificial bone graft materials could solve some of the problems associated with the gold standard use of natural bone graft such as limited bone material, pain at the donor site and rejections if donor tissue is used. We have previously described new acrylate base nanocomposite hydrogels as bone graft materials. In the present paper, we describe the integration of silver nanoparticles in the polymeric mineralized biomaterial to provide non-antibiotic antibacterial activity against Staphylococcus epidermidis and Methicillin-resistant Staphylococcus aureus. Two different crosslinking degrees were tested and the silver nanoparticles were integrated into the composite matrix by means of three different methods: entrapment in the polymeric hydrogel before the mineralization; diffusion during the process of calcium phosphate crystallization and adsorption post-mineralization. The latter being generally the most effective method of encapsulation; however, the adsorption of silver nanoparticles inside the pores of the biomaterial led to a decreasing antibacterial activity for adsorption time longer than 2 days.

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Acrylate based hydrogels were prepared.

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Hydrogels were mineralized through reaction diffusion.

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Silver nanoparticles were encapsulated in different ways.

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Nanoparticle adsorption after mineralization was the most effective antibacterial method.