Biogenic production of silver nanoparticles by Enterobacter cloacae Ism26

Green Silver Nanoparticles: An Antibacterial Mechanism

Silver nanoparticles (AgNPs) are a promising tool in the fight against pathogenic microorganisms. "Green" nanoparticles are especially valuable due to their environmental friendliness and lower energy consumption during production, as well as their ability to minimize the number of toxic by-products. This review focuses on the features of AgNP synthesis using living organisms (bacteria, fungi, plants) and the involvement of various biological compounds in this process. The mechanism of antibacterial activity is also discussed in detail with special attention given to anti-biofilm and anti-quorum sensing activities. The toxicity of silver nanoparticles is considered in light of their further biomedical applications.

Comprehensive evaluation of the antibacterial and antibiofilm activities of NiTi orthodontic wires coated with silver nanoparticles and nanocomposites: an in vitro study

BACKGROUND

Fixed orthodontic appliances act as a niche for microbial growth and colonization. Coating orthodontic wires with antimicrobial silver nanoparticles (AgNPs) and nanocomposite was adopted in this study to augment the biological activity of these wires by increasing their antibacterial and antibiofilm properties and inhibiting bacterial infections that cause white spot lesions and lead to periodontal disease.

METHODS

Three concentrations of biologically synthesized AgNPs were used for coating NiTi wires. The shape, size, and charge of the AgNPs were determined. Six groups of 0.016 × 0.022-inch NiTi orthodontic wires, each with six wires, were used; and coated with AgNPs and nanocomposites. The antimicrobial and antibiofilm activities of these coated wires were tested against normal flora and multidrug-resistant bacteria (Gram-positive and Gram-negative bacterial isolates). The surface topography, roughness, elemental percentile, and ion release were characterized.

RESULTS

AgNPs and nanocomposite coated NiTi wires showed significant antimicrobial and antibiofilm activities. The chitosan-silver nanocomposite (CS-Ag) coated wires had the greatest bacterial growth inhibition against both Gram-positive and Gram-negative bacteria. The surface roughness of the coated wires was significantly reduced, impacting the surface topography and with recorded low Ni and Ag ion release rates.

CONCLUSIONS

NiTi orthodontic wires coated with AgNPs, and nanocomposites have shown increased antimicrobial and antibiofilm activities, with decreased surface roughness, friction resistance and limited- metal ion release.

Biofabrication of silver nanoparticles employing biomolecules of Paraclostridium benzoelyticum strain: Its characterization and their in-vitro antibacterial, anti-aging, anti-cancer and other biomedical applications

The current study aims to utilize the bacteria Paraclostridium benzoelyticum strain 5610 to synthesize bio-genic silver nanoparticles (AgNPs). Biogenic AgNPs were thoroughly examined using various characterization techniques such as UV-spectroscopy, XRD, FTIR, SEM, and EDX. Synthesis of AgNPs was confirmed by UV-vis analysis resulting in absorption peak at 448.31 nm wavelength. The SEM analysis indicated the morphological characteristics and size of AgNPs which was 25.29 nm. The face centered cubic (FCC) crystallographic structure was confirmed by XRD. Furthermore, FTIR study affirmed the capping of AgNPs by different compounds found in biomass of the Paraclostridium benzoelyticum strain 5610. Later, EDX was used to determine the elemental composition with respective concentration and distribution. Additionally, in the current study the antibacterial, anti-inflammatory, antioxidant, anti-aging, and anti-cancer ability of AgNPs was assessed. The antibacterial activity of AgNPs was tested against four distinct sinusitis pathogens: Haemophilus in-fluenza, Streptococcus pyogenes, Moraxella catarrhalis and Streptococcus pneumonia. AgNPs shows significant inhibition zone against Streptococcus pyogenes 16.64 ± 0.35 followed by 14.32 ± 071 for Moraxella catarrhalis. Similarly, the antioxidant potential was found maximum (68.37 ± 0.55%) at 400 μg/mL and decrease (5.48 ± 0.65%) at 25 μg/mL, hence the significant antioxidant ability was observed. Furthermore, anti-inflammatory activity of AgNPs shows the strongest inhibitory action (42.68 ± 0.62%) for 15-LOX with lowest inhibition activity for COX-2 (13.16 ± 0.46%). AgNPs have been shown to exhibit significant inhibitory actions against the enzyme elastases AGEs (66.25 ± 0.49%), which are followed by AGEs of visperlysine (63.27 ± 0.69%). Furthermore, the AgNPs show high toxicity against HepG2 cell line which shows 53.543% reduction in the cell viability after 24 h of treatment. The anti-inflammatory activity demonstrated a potent inhibitory effect of the bio-inspired AgNPs. Overall, the biogenic AgNPs have the ability to be served for the treatments of anti-aging and also due to their anti-cancer, antioxidant abilities NPs may be a useful therapy choice for a variety of disorders including cancer, bacterial infections and other inflammatory diseases. Moreover, further studies are required in the future to evaluate their in vivo biomedical applications. HIGHLIGHTS: Biogenic synthesis of AgNPs using Paraclostridium benzoelyticum Strain for the first time. FTIR analysis confirmed capping of potent biomolecules which are of great use in applied field especially Nanomedicines. Notable antimicrobial activity against sinusitis bacteria and cytotoxic potential of synthesized AgNPs on in vitro basis produce a new idea shifting us to treat cancerous cell lines.

Transporter drives the biosorption of heavy metals by Stenotrophomonas rhizophila JC1

To better understand the function of transporter in heavy metal detoxification of bacteria, the transporters associated with heavy metal detoxification in S. rhizophila JC1 were analyzed, among which four members were verified by RT-qPCR. In addition, the removal rates of four single metal ions (Cr⁶⁺, Cu²⁺, Zn²⁺, Pb²⁺) and polymetallic ions by strain JC1 were studied, respectively. We also researched the physiological response of strain JC1 to different metal stress via morphological observation, elemental composition, functional group and membrane permeability analysis. The results showed that in the single metal ion solution, removal capacities of Cu²⁺ (120 mg/L) and Cr⁶⁺ (80 mg/L) of S. rhizophila JC1 reached to 79.9% and 89.3%, respectively, while in polymetallic ions solution, the removal capacity of each metal ion all decreased, and in detail, the adsorption capacity was determined Cr⁶+>Cu²⁺>Zn²⁺>Pb²⁺ under the same condition. The physiological response analyses results showed that extracellular adsorption phenomena occurred, and the change of membrane permeability hindered the uptake of metal ions by bacteria. The analysis of transporters in strain JC1 genome illustrated that a total of 323 transporters were predicted. Among them, two, six and five proteins of the cation diffusion facilitator, resistance-nodulation-division efflux and P-type ATPase families were, respectively, predicted. The expression of corresponding genes showed that the synergistic action of correlative transporters played important roles in the process of adsorption. The comparative genomics analysis revealed that S. rhizophila JC1 has long-distance evolutionary relationships with other strains, but the efflux system of S. rhizophila JC1 contained the same types of metal transporters as other metal-resistant bacteria.

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.

Synthetic preparations and atomic scale engineering of silver nanoparticles for biomedical applications

Owing to their peculiar oxidative effect, silver cations (Ag⁺) are well known for their antimicrobial properties and explored as therapeutic agents for biomedical applications. Size control with improved dispersion and stability are the key factors of Ag NPs (silver nanoparticles) to be used in biomedical applications. Silver based nano-materials are highly efficient due to their biological, chemical and physical properties in comparison with bulk silver. Atomic scale fabrication is achieved by rearranging the internal components of a material, in turn, influencing the mechanical, electrical, magnetic, thermal and chemical properties. For instance, size and shape have a strong impact on the optical, thermal and catalytic properties of Ag NPs. Such properties can be tuned by controlling the surface/volume ratio of Ag nanostructures with a small size (ideally <100 nm), in turn showing peculiar biological activity different from that of bulk silver. Silver nanomaterials such as nanoparticles, thin films and nanorods can be synthesized by various physical, chemical and biological methods whose most recent implementations will be described in this review. By controlling the structure-functionality relationship, silver based nano-materials have high potential for commercialization in biomedical applications. Antimicrobial, antifungal, antiviral, and anti-inflammatory Ag NPs can be applied in several fields such as pharmaceutics, sensors, coatings, cosmetics, wound healing, bio-labelling agents, antiviral drugs, and packaging.

A Review on Silver Nanoparticles: Classification, Various Methods of Synthesis, and Their Potential Roles in Biomedical Applications and Water Treatment

Recent developments in nanoscience have appreciably modified how diseases are prevented, diagnosed, and treated. Metal nanoparticles, specifically silver nanoparticles (AgNPs), are widely used in bioscience. From time to time, various synthetic methods for the synthesis of AgNPs are reported, i.e., physical, chemical, and photochemical ones. However, among these, most are expensive and not eco-friendly. The physicochemical parameters such as temperature, use of a dispersing agent, surfactant, and others greatly influence the quality and quantity of the synthesized NPs and ultimately affect the material’s properties. Scientists worldwide are trying to synthesize NPs and are devising methods that are easy to apply, eco-friendly, and economical. Among such strategies is the biogenic method, where plants are used as the source of reducing and capping agents. In this review, we intend to debate different strategies of AgNP synthesis. Although, different preparation strategies are in use to synthesize AgNPs such as electron irradiation, optical device ablation, chemical reduction, organic procedures, and photochemical methods. However, biogenic processes are preferably used, as they are environment-friendly and economical. The review covers a comprehensive discussion on the biological activities of AgNPs, such as antimicrobial, anticancer anti-inflammatory, and anti-angiogenic potentials of AgNPs. The use of AgNPs in water treatment and disinfection has also been discussed in detail.

Biological Nanofactories: Using Living Forms for Metal Nanoparticle Synthesis

Metal nanoparticles are nanosized entities with dimensions of 1-100 nm that are increasingly in demand due to applications in diverse fields like electronics, sensing, environmental remediation, oil recovery and drug delivery. Metal nanoparticles possess large surface energy and properties different from bulk materials due to their small size, large surface area with free dangling bonds and higher reactivity. High cost and pernicious effects associated with the chemical and physical methods of nanoparticle synthesis are gradually paving the way for biological methods due to their eco-friendly nature. Considering the vast potentiality of microbes and plants as sources, biological synthesis can serve as a green technique for the synthesis of nanoparticles as an alternative to conventional methods. A number of reviews are available on green synthesis of nanoparticles but few have focused on covering the entire biological agents in this process. Therefore present paper describes the use of various living organisms like bacteria, fungi, algae, bryophytes and tracheophytes in the biological synthesis of metal nanoparticles, the mechanisms involved and the advantages associated therein.

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.

Pseudomonas aeruginosa synthesized silver nanoparticles inhibit cell proliferation and induce ROS mediated apoptosis in thyroid cancer cell line (TPC1)

We used cell-free culture filtrate of Pseudomonas aeruginosa as a reducing mediator of AgNO₃ to silvernanoparticles (AgNPs) and possibly used as a potential anticancer agent against thyroid cancer cells (TPC1). The bio-generation of AgNPs was firmly established by taking a UV spectrum at 380-500 nm wavelength. The Fourier transform spectrum analysis reveals the association of alcohol, phenol and aromatic functional groups with P. aeruginosa synthesized AgNPs (Ps-AgNPs). By observing under transmission electron microscopy (TEM), the size and structure of the Ps-AgNPs were characterized as the size was 30-70 nm and spherical in shape. The concentration-dependent cytotoxicity of Ps-AgNPs on TPC1 cells was observed and IC50 value was calculated. The alteration of oxidative and antioxidant biomarkers in Ps-AgNPs treated cells were observed. The induced apoptosis was determined by staining the Ps-AgNPs treated cells with DCFH-DA, Rh-123 dye, Acridine Orange (AO) and ethidium bromide (EtBr). Increased level of intracellular reactive oxygen species (ROS) generation and decreased level of mitochondrial membrane potential was observed in Ps-AgNPs treated TPC1 cells. Moreover, the apoptotic morphological changes were explored, which indicates increased apoptosis by inducing cell membrane damage in Ps-AgNPs treated cells. This biogenic approach will enable an effective and significant improvement in nano-oncotherapy.

Silver Nanoparticles: Mechanism of Action and Probable Bio-Application

This review is devoted to the medical application of silver nanoparticles produced as a result of "green" synthesis using various living organisms (bacteria, fungi, plants). The proposed mechanisms of AgNPs synthesis and the action mechanisms on target cells are highlighted.

Biochemical and genetic basis of cadmium biosorption by Enterobacter ludwigii LY6, isolated from industrial contaminated soil

In this study, a cadmium-tolerant bacterium, Enterobacter ludwigii LY6, was isolated from cadmium-contaminated soil in Shifang, Sichuan province, China. The cadmium chloride removal rate of the strain LY6 with a treatment of 100 mg/L cadmium chloride reached 56.0%. Scanning electron microscopy showed that exopolysaccharides (EPS) might be the main means of cadmium adsorption by the strain. X-ray powder diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS) analyses indicated that cadmium sulfide nanoparticles formed on the surface of bacteria cultured in a medium containing 100 mg/L cadmium chloride. In addition, the expression of several genes increased with the increase of the cadmium concentration in the medium, including the multiple antibiotic resistance proteins marA and marR, and the cold shock protein CspA. GO functions, such as the redox activity, respiratory chain and transport functions, and KEGG pathways involved in "bacterial chemotaxis" and "terpenoid backbone biosynthesis" were found to be closely related to bacterial cadmium tolerance and biosorption. This is the first report that E. ludwigii can reduce sulfate to form cadmium sulfide nanoparticles under high concentration cadmium exposure. The genes related to cadmium tolerance identified in this study lay a foundation for the genetic breeding of cadmium-tolerant strains.

Biogenic Metal Nanoparticles: A New Approach to Detect Life on Mars?

Metal nanoparticles (MNPs) have been extensively studied. They can be produced via different methods (physical, chemical, or biogenic), but biogenic synthesis has become more relevant, mainly for being referred by many as eco-friendly and more advantageous than others. Biogenic MNPs have been largely used in a wide variety of applications, from industry, to agriculture, to health sectors, among others. Even though they are increasingly researched and used, there is still space for exploring further applications and increasing their functionality and our understanding of their synthesis process. Here, we provide an overview of MNPs and biogenic MNPs, and we analyze the potential application of their formation process to astrobiology and the detection of life on Mars and other worlds. According to current knowledge, we suggest that they can be used as potential biosignatures in extra-terrestrial samples. We present the advantages and disadvantages of this approach, suggest further research, and propose its potential use for the search for life in future space exploration.

Elemental Silver Nanoparticles: Biosynthesis and Bio Applications

The data on the specifics of synthesis of elemental silver nanoparticles (Ag-NP) having various geometric shapes (pseudo spherical, prismatic, cubic, trigonal-pyramidal, etc.), obtained by using various biological methods, and their use in biology and medicine have been systematized and generalized. The review covers mainly publications published in the current 21st century. Bibliography: 262 references.