Bio-synthesis and antimicrobial activity of silver nanoparticles using anaerobically digested parthenium slurry

Ecofriendly synthesis characterization and biological activities of Eruca sativa mediated silver oxide nanoparticles

One of the popular subjects of millennia is the synthesis of nanostructures, their applications in numerous fields, and their interaction with various biological systems, making them appealing for drug delivery systems, and diagnostic and therapeutic agents. In this study, silver oxide nanoparticles were synthesized using E. sativa (ES) aqueous extract. The biosynthesis was followed via UV-vis spectroscopy by analysis, FTIR, XRD, TEM, and Zeta potential to further analyze the synthesized nanoparticles. Furthermore, the biosynthesized silver oxide nanoparticles (Ag2ONPs) were checked through various biological activities. The antioxidative potential was assessed by performing a DPPH radical scavenging assay, total reducing power assay, and total antioxidant capacity assay. Antimicrobial potential was observed against various bacterial and fungal strains. Likewise, Artemia salina (brine shrimps) was used to study cytotoxicity, while VERO and HEK-293 cell lines were applied to check the biocompatibility of synthesized NPs. Anticancer potential was evaluated against the Hep-2 cells by utilizing an MTT assay. A mean crystallite ~ 50 nm size is evidenced by TEM analysis. Notable antimicrobial activity was detected with various bacterial and fungal strains with maximum ZOI by B. subtilis was 18.5 ± 2.36 mm at 1000 µg/mL and A. niger reveals a minimum ZOP of 16 ± 1.7 mm at 1000 µg/mL respectively. A dose-dependent response was observed in biological evaluation against A. salina (LC50: 12.21 µg/mL), DPPH (IC50: 62.36 µg/mL), VERO cell line (IC50: 43.11 µg/mL), HEK-293 cell line (IC50: 26.56 µg/mL), and Hep-2 cell line (IC50: 9.97 µg/mL). The multifaceted attributes of ES-Ag2ONPs encompassing antimicrobial, antioxidant, cytotoxic, and anticancer properties render them a versatile platform in drug delivery and biomedical horizons. However, detailed investigation and clinical trials will undoubtedly provide translational applications in diverse fields.

Biosynthesis of silver nanoparticles using soil actinobacterium Streptomyces anthocyanicus and investigation of their larvicidal potentials against Culex quinquefasciatus Aedes aegypti, and Anopheles stephensi

Mosquitoes represent a considerable risk to human health due to their role in transmitting various pathogens responsible for diseases like chikungunya, malaria, dengue, and Japanese encephalitis. There is an immediate necessity to explore innovative biological strategies to combat mosquito-borne illnesses. One promising avenue in current research is the development of bioinsecticides utilizing advanced nanotechnology. Therefore, this study aimed to synthesize silver nanoparticles from the actinobacterial strain Streptomyces anthocyanicus (OR186732), isolated from the Western Ghats in Tamil Nadu, India. The AgNPs were synthesized and then characterized using UV-visible spectroscopy, identifying a prominent absorption peak at 424 nm. The identification of different functional groups within the AgNPs was confirmed through FTIR. The produced AgNPs were shown to be crystalline by XRD analysis. The nanoparticles were characterized using FESEM, HRTEM, and EDX to analyze their morphology, size, and elemental composition. The stability was assessed through Zeta potential measurements, which were measured at -0.2 mV. The synthesized AgNPs showed strong larvicidal effects against Culex quinquefasciatus (LC50 = 2.924 ppm), Aedes aegypti (LC50 = 3.245 ppm), and Anopheles stephensi (LC50 = 3.767 ppm). Furthermore, the AgNPs were observed to significantly increase the levels of antioxidant enzymes such as SOD and GPx at high concentrations. In contrast, levels of detoxifying enzymes such as AChE and GST levels were reduced. Histological analysis of mosquito larvae treated with AgNPs revealed significant damage to the midgut tissues. The research suggests that AgNPs synthesized by Actinobacteria could be an environmentally friendly option for biological mosquito control.

A review on green synthesis of silver nanoparticles (SNPs) using plant extracts: a multifaceted approach in photocatalysis, environmental remediation, and biomedicine

A sustainable and viable alternative for conventional chemical and physical approaches is the green production of silver nanoparticles (SNPs) using plant extracts. This review centers on the diverse applications of plant-mediated SNPs in biomedicine, environmental remediation, and photocatalysis. Ocimum sanctum (tulsi), Curcuma longa (turmeric), and Azadirachta indica (neem) and many others are plant extracts that have been used as stabilizing and reducing agents because of their extensive phytochemical profiles. The resulting SNPs have outstanding qualities, such as better photocatalytic degradation of organic dyes like methylene blue, antibacterial efficacy towards multidrug-resistant pathogens, biocompatibility for possible therapeutic applications, and regulated magnitude (10-50 nm), enhanced rigidity, and tunable surface plasmon resonance. Significant effects of plant extract type, amount, and synthesis parameters on the physical and functional characteristics of SNPs are revealed by key findings. Along with highlighting important issues and potential paths forward, this review also underlines the necessity of scalable production, thorough toxicity evaluations, and investigating the incorporation of SNPs into commercial applications. This work highlights how plant-based SNPs can be used to address global environmental and biological concerns by straddling the division between sustainable chemistry and nanotechnology.

Preparation methods, applications, toxicity and mechanisms of silver nanoparticles as bactericidal agent and superiority of green synthesis method

Silver nanoparticles (SNPs) are a type of nanomaterial with wide applications in water treatment, medicine, food packaging, and industrial processes. Their unique optical, electrical, thermal conductivity, and biological properties distinguish them from other metal ions and liken them to noble metals like gold and copper. The present review explores the diverse applications, preparation techniques, mechanism of action of SNPs, and properties of SNPs focusing on their bactericidal activities and potential impacts on human health. Different preparation methods, encompassing chemical, physical, and biological techniques, were reviewed and analyzed to comprehend their effect on the properties and applications of SNPs. Studies revealed that the SNPs exhibit excellent antibactericidal properties. Mechanisms underlying their antimicrobial effects were explored, primarily focusing on pathogen-scavenging activities. Despite the promising benefits of SNPs, their potential toxicity to human health must be carefully managed. Regulatory standards, such as those set by WHO and USEPA; establish a maximum tolerable limit of 0.1 mg/L to mitigate health risks associated with SNP exposure. It is recommended to continue research into safer applications and alternative formulations of SNPs to minimize potential health risks while maximizing their beneficial applications across different industries.

Preparation of Flower-like Nanosilver Based on Bioderived Caffeic Acid for Raman Enhancement and Dye Degradation

In this study, a simple, green, and low-cost room temperature synthesis of broccoli-like silver nanoflowers (AgNF) with a particle size of about 300-500 nm was developed using plant-derived caffeic acid as a reducing agent and polyvinylpyrrolidone as a dispersant under ultrasound assistance. The flower clusters covered by small nanocrystals of 20-50 nm significantly enhance the electromagnetic field signals. AgNF was deposited on the surface of silicon wafers as a surface-enhanced Raman spectroscopy sensor for the detection of probe molecules such as rhodamine 6G (R6G) and malachite green with high sensitivity, homogeneity, and reproducibility. AgNF was deposited on cotton fabrics in the form of composites to catalyze the degradation of dye pollutants such as R6G, MG, and methyl orange in the presence of sodium borohydride. 0.1 g of AgNF/cotton fabric could assist 15 mmol/L NaBH4 to achieve over 90% degradation of various dyes as well as a high concentration of dyes in 12 min with good reusability and recyclability. The AgNF synthesized in this work can not only monitor the type and amounts of pollutants (dyes) in wastewater but also catalyze the rapid degradation of dyes, which is expected to be valuable for industrial applications.

Green Synthesis of Silver Nanoparticles using Cirsium congestum Extract Modified by Chitosan/Alginate: Bactericidal Activity against Pathogenic Bacteria and Cytotoxicity Analysis in Normal Cell Line

AIM

The study aimed to determine in vitro pharmacological effects of modified Ag nanoparticles (AgNPs).

BACKGROUND

AgNPs are considered antimicrobial agents. However, the cytotoxicity of chemically synthesized AgNPs (cAgNPs) has raised challenges that limit their use.

OBJECTIVE

The purpose of the study was to examine the antimicrobial and cytotoxicity effects of AgNPs synthesized using Cirsium congestum extract modified by chitosan/alginate AgNPS (Ch/ALG-gAgNPs).

METHODS

Nanoparticles were characterized using TEM, DLS, XRD, and FTIR. Resistant strains of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were used for the antimicrobial analysis of Ch/ALG-gAgNPs using disc diffusion and microdilution methods. The effects of NPs on cell viability and apoptosis in L929 normal cells were determined using MTT assay and annexin/PI staining, respectively.

RESULTS

Physicochemical characterizations confirmed Ch/ALG-gAgNPs to be spherical and uniformly dispersed, and their size ranged from 50 to 500 nm. Ch/ALG-gAgNPs inhibited the growth of microbial strains in a dose-dependent manner. The antibacterial effect of Ch/ALG-gAgNPs was significantly higher than cAgNPs. The Ch/ALG-gAgNPs showed little cytotoxicity against normal cells at concentrations less than 50 μg/ml. Cytotoxicity effects of Ch/ALG-gAgNP were less than cAgNPs. Flow cytometry and real-time PCR results showed a decrease in apoptosis percentage and BAX marker in the presence of Ch/ALG-gAgNPs relative to when the cell was treated with cAgNPs.

CONCLUSION

Current findings introduce novel gAgNPs modified with chitosan/alginate for use in medicine.

Bioinspired Multifunctional Silver Nanoparticles for Optical Sensing Applications: A Sustainable Approach

Silver nanoparticles developed via biosynthesis are the most fascinating nanosized particles and encompassed with excellent physicochemical properties. The bioinspired nanoparticles with different shapes and sizes have attracted huge attention due to their stability, low cost, environmental friendliness, and use of less hazardous chemicals. This is an ideal method for synthesizing a range of nanosized metal particles from plants and biomolecules. Optical biosensors are progressively being fabricated for the attainment of sustainability by using opportunities offered by nanotechnology. This review focuses mainly on tuning the optical properties of the metal nanoparticles for optical sensing to explore the importance and applications of bioinspired silver nanoparticles. Further, this review deliberates the role of bioinspired silver nanoparticles (Ag NPs) in biomedical, agricultural, environmental, and energy applications. Profound insight into the antimicrobial properties of these nanoparticles is also appreciated. Tailor-made bioinspired nanoparticles with effectuating characteristics can unsurprisingly target tumor cells and distribute enwrapped payloads intensively. Existing challenges and prospects of bioinspired Ag NPs are also summarized. This review is expected to deliver perceptions about the progress of the next generation of bioinspired Ag NPs and their outstanding performances in various fields by promoting sustainable practices for fabricating optical sensing devices.

Antimicrobial and Apoptotic Efficacy of Plant-Mediated Silver Nanoparticles

Phytogenically synthesised nanoparticle (NP)-based drug delivery systems have promising potential in the field of biopharmaceuticals. From the point of view of biomedical applications, such systems offer the small size, high surface area, and possible synergistic effects of NPs with embedded biomolecules. This article describes the synthesis of silver nanoparticles (Ag-NPs) using extracts from the flowers and leaves of tansy (Tanacetum vulgare L.), which is known as a remedy for many health problems, including cancer. The reducing power of the extracts was confirmed by total phenolic and flavonoid content and antioxidant tests. The Ag-NPs were characterised by various analytical techniques including UV-vis spectroscopy, scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), Fourier transform infrared (FT-IR) spectroscopy, and a dynamic light scattering (DLS) system. The obtained Ag-NPs showed higher cytotoxic activity than the initial extracts against both human cervical cancer cell lines HeLa (ATCC CCL-2) and human melanoma cell lines A375 and SK-MEL-3 by MTT assay. However, the high toxicity to Vero cell culture (ATCC CCL-81) and human fibroblast cell line WS-1 rules out the possibility of their use as anticancer agents. The plant-mediated Ag-NPs were mostly bactericidal against tested strains with MBC/MIC index ≤4. Antifungal bioactivity (C. albicans, C. glabrata, and C. parapsilosis) was not observed for aqueous extracts (MIC > 8000 mg L^-1), but Ag-NPs synthesised using both the flowers and leaves of tansy were very potent against Candida spp., with MIC 15.6 and 7.8 µg mL^-1, respectively.

Nanosilver/DCOIT-containing surface coating effectively and constantly reduces microbial load in emergency room surfaces

BACKGROUND

Colonization of near-patient surfaces in hospitals plays an important role as a source of healthcare-associated infections. Routine disinfection methods only result in short-term elimination of pathogens.

AIM

To investigate the efficiency of a newly developed antimicrobial coating containing nanosilver in long-term reduction of bacterial burden in hospital surfaces to close the gap between routine disinfection cycles.

METHODS

In this prospective, double-blinded trial, frequently touched surfaces of a routinely used treatment room in an emergency unit of a level-I hospital were treated with a surface coating (nanosilver/DCOIT-coated surface, NCS) containing nanosilver particles and another organic biocidal agent (4,5-dichloro-2-octyl-4-isothiazolin-3-one, DCOIT), whereas surfaces of another room were treated with a coating missing both the nanosilver- and DCOIT-containing ingredient and served as control. Bacterial contamination of the surfaces was examined using contact plates and liquid-based swabs daily for a total trial duration of 90 days. After incubation, total microbial counts and species were assessed.

FINDINGS

In a total of 2880 antimicrobial samples, a significant reduction of the overall bacterial load was observed in the NCS room (median: 0.31 cfu/cm²; interquartile range: 0.00-1.13) compared with the control coated surfaces (0.69 cfu/cm²; 0.06-2.00; P < 0.001). The nanosilver- and DCOIT-containing surface coating reduced the relative risk of a critical bacterial load (defined as >5 cfu/cm²) by 60% (odds ratio 0.38, P < 0.001). No significant difference in species distribution was detected between NCS and control group.

CONCLUSION

Nanosilver-/DCOIT-containing surface coating has shown efficiency for sustainable reduction of bacterial load of frequently touched surfaces in a clinical setting.

Ultra-sonication-enhanced green synthesis of silver nanoparticles using Barleria buxifolia leaf extract and their possible application

The main aim of the study, green route to the synthesis of silver nanoparticles (AgNPs) is a new technique that has recently gained popularity due to several advantages over conventional chemical methods. The objective of the study was focused on the green synthesis of AgNPs using Barleria buxifolia leaf extract via a rapid and eco-friendly ultrasonic-assisted technique. The obtained AgNPs were characterized using ultraviolet-visible (UV-Vis) absorption spectrum of the organically reduced silver showed a surface plasmon peak at 435 nm, characteristic for silver colloidal solutions. UV-Vis absorption spectrum, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS) analysis showed that the obtained AgNPs were dispersed spheres with a uniform size of 80 nm. Furthermore, the Fourier-transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD) analysis indicated that the surface of the obtained AgNPs was covered with organic molecules in plant extracts. Green synthesized AgNPs showed the highest antioxidant, antibacterial and anti-biofilm activity than a plant extract. In vitro anticancer assay demonstrated half-maximal inhibitory concentration (IC₅₀) values of 31.42, 30.67, 51.07 and 56.26 µg/mL against MCF-7, HeLa and HepG2 cancer cell lines, respectively, which confirms its potent anticancer action. The biocompatibility of green synthesized AgNPs is confirmed by their lack of cytotoxicity against normal human cells. The potent bioactivity exhibited by the green synthesized AgNPs leads towards the multiple use as antioxidant, antibacterial, anti-biofilm and cytotoxic agent.

Biosynthesis and characterization of silver nanoparticles from symbiotic bacteria Xenorhabdus nematophila and testing its insecticidal efficacy on Spodoptera litura larvae

Spodoptera litura, one of the polyphagous pests, causes huge economical lose and use of chemical pesticide causes impact to the environmental. The present study deals with the use of cell- free supernatant of bacteria Xenorhabdus nematophila NP-1 strain for synthesizing silver nanoparticles and analyzing its larvicidal ability against Spodoptera litura. Color change from yellow to dark brown specifies the synthesis of AgNPs. UV-Vis spec indicates the presences of AgNPs at 440 nm λ_max and functional groups; alcohols, carboxylic acids, aromatics, alkylhalides, ethers and phenols were confirmed by FTIR. SEM revealed the synthesized AgNPs is in spherical shape, EDaX confirms the elemental composition and the crystalline nature were observed using XRD. GC-MS analysis showed presence of Benzencepropanoic acid, 1, 3, 5 Trichloropent-2-ene, 1,1-Dichloro-2,3- dicmethycycloprone and 1,2-benzenedicarboxylic acid bioactive compounds some of which may be responsible for insecticidal and antibacterial activity. The antibacterial activity against S. aureus, B. subtilis and K. pneumoniae showed maximum zone of inhibition at 100 µL/mL. Larvicidal activity of S. litura shows highest mortality at 48 h. In potted plant experiment, AgNPs treated plants showed less damage, with less leaf consumption by S. litura larvae. Further, the synthesis of AgNPs were targeted to zebrafish embryos (non- target organism) and it didn't exhibit any toxic effect even at higher concentration. Our experiment concludes that, AgNPs synthesized using NP-1 strain has highest antimicrobial and insecticidal activity, which can be used in biomedical and biopesticides.

Novel fabrication of SiO2/Ag nanocomposite by gamma irradiated Fusarium oxysporum to combat Ralstonia solanacearum

The bacterial wilt is a global destructive plant disease that initiated by the phytopathogenic Ralstonia solanacearum. This study display a novel biofabrication of silica/silver nanocomposite using Fusarium oxysporum-fermented rice husk (RH) under solid state fermentation (SSF). The biofabricated nanocomposite was characterized by XRD, UV-Vis. spectroscopy, DLS, SEM, EDX elemental mapping, and TEM analyses as well as investigated for anti-R. solanacearum activity. Response surface methodology was also processed for optimizing the biofabrication process and improving the anti-bacterial activity of the fabricated nanocomposite. Maximum suppression zone of 29.5 mm against R. solanacearum was reached at optimum RH content of 6.0 g, AgNO3 concentration of 2.50 mM, reaction pH of 6.3, and reaction time of 2 days. The anti-R. solanacearum activity of the fabricated nanocomposite was further improved by exposing the F. oxysporum strain to a gamma irradiation dose of 200 Gy. In conclusion, RH recycling under SSF by F. oxysporum could provide an innovative, facile, non-expensive, and green approach for fabricating SiO2/Ag nanocomposite that could be applied efficiently as an eco-friendly antibacterial agent to combat R. solanacearum in agricultural applications. Moreover, the developed method could serve as a significant platform for the designing of new nanostructures for broad applications.

Pharmacological properties of biogenically synthesized silver nanoparticles using endophyte Bacillus cereus extract of Berberis lyceum against oxidative stress and pathogenic multidrug-resistant bacteria

The emergence of multidrug resistance in pathogenic bacteria limits the utilization of available antibiotics. The development of alternate options to treat infectious diseases is the need of the day.The present study was aimed to synthesize, characterize and evaluate the bioactive properties of silver nanoparticles. Endophytic bacterium Bacillus cereus (MT193718) isolated from Berberis lycium was used to synthesize biocompatible silver nanoparticles. Antibacterial properties of AgNPs were evaluated against clinically isolated multidrug-resistant strains of Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae. AgNPs indicated significant antibacterial activity against S. aureus and K. pneumoniae fwith a zone of inhibition of 17 and 18 mm at a concentration of 1000 µg/ mL with minimum inhibitory concentration of 15.6 and 62.5 µg/mL respectively. Significant antioxidant activity with an IC50 value of 9.5 µg/mL was recorded. Biosynthesized AgNPs were found compatible with red blood cells at a concentration of 31.5 µg/ml with no clumping of erythrocytes. The study suggested that AgNPs synthesized by the endophytic bacterium Bacillus cereus are biologically active and can be used as antioxidant and antibacterial agents against drug-resistant bacteria.

Silver nanoparticles, a promising treatment against clinically important fluconazole-resistant Candida glabrata

Resistance to azole antifungal agents is a challenging limitation in Candida glabrata treatment. It is associated with decreased intracellular concentrations of antifungal agents as a result of overexpression of efflux pumps on the cellular plasma membranes. This work evaluates the potential of silver nanoparticles (AgNPs) to reverse the resistance of fungal cells to fluconazole. Silver nanoparticles were prepared using wet chemical method and characterised by UV-Vis spectrophotometry, dynamic light scattering, and zeta potential. Broth microdilution and pour plates methods were used to study the anticandidal activity using two C. glabrata fluconazole-resistant strains (DSY565 and CBS138) known to overexpress active efflux pumps, and a standard fluconazole sensitive strain ATCC 22553. Silver nanoparticles-fluconazole combinations decreased concentrations of fluconazole substantially without compromising the activity. These findings suggest that AgNPs enhance the efficacy of fluconazole and offer a promising application in therapy of C. glabrata infections.

Biocidal Activity of Metal Nanoparticles Synthesized by Fusarium solani against Multidrug-Resistant Bacteria and Mycotoxigenic Fungi

Antibiotic resistance by pathogenic bacteria and fungi is one of the most serious global public health problems in the 21^st century, directly affecting human health and lifestyle. Pseudomonas aeruginosa and Staphylococcus aureus with strong resistance to the common antibiotics have been isolated from Intensive Care Unit patients at Zagazig Hospital. Thus, in this study we assessed the biocidal activity of nanoparticles of silver, copper and zinc synthesized by Fusarium solani KJ 623702 against these multidrug resistant-bacteria. The synthesized Metal Nano-particles (MNPs) were characterized by UV-Vis spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and Zeta potential. The Fourier transform infrared spectroscopy (FTIR) result showed the presence of different functional groups such as carboxyl, amino and thiol, ester and peptide bonds in addition to glycosidic bonds that might stabilize the dispersity of MNPs from aggregation. The antimicrobial potential of MNPs by F. solani against the multidrug-resistant (MDR) P. aeruginosa and S. aureus in addition to the mycotoxigenic Aspergillus awamori, A. fumigatus and F. oxysporum was investigated, based on the visual growth by diameter of inhibition zone. Among the synthesized MNPs, the spherical AgNPs (13.70 nm) displayed significant effect against P. aeruginosa (Zone of Inhibition 22.4 mm and Minimum Inhibitory Concentration 21.33 µg/ml), while ZINC oxide Nano-Particles were the most effective against F. oxysporum (ZOI, 18.5 mm and MIC 24.7 µg/ml). Transmission Electron Microscope micrographs of AgNP-treated P. aeruginosa showed cracks and pits in the cell wall, with internalization of NPs. Production of pyocyanin pigment was significantly inhibited by AgNPs in a concentration-dependent manner, and at 5-20 µg of AgNPs/ml, the pigment production was reduced by about 15-100%, respectively.

New avenues of controlling microbial infections through anti-microbial and anti-biofilm potentials of green mono-and multi-metallic nanoparticles: A review

Nanoparticles synthesized through the green route deserve special mention because this green technology is not only energy-efficient and cost-effective but also amenable to the environment. Various biological resources have been used for the generation of these 'green nanoparticles'. Biological wastes have also been focused in this direction thereby promoting the value of waste. Reports indicate that green nanoparticles exhibit remarkable antimicrobial activitiesboth singly as well as in combination with standard antibiotics. The current phenomenon of multi-drug resistance has resulted due to indiscriminate administration of high-doses of antibiotics followed by significant toxicity. In the face of this emergence of drug-resistant microbesthe efficacy of green nanoparticles might prove greatly beneficial. Microbial biofilm is another hurdle in the effective treatment of diseases as the microorganismsbeing embedded in the meshwork of the biofilmevade the antimicrobial agents. Nanoparticles may act as a ray of hope on the face of this challenge tooas they not only destroy the biofilms but also lessen the doses of antibiotics requiredwhen administered in combination with the nanoparticles. It should be further noted that the resistance mechanisms exhibited by the microorganisms seem not that relevant for nanoparticles. The current review, to the best of our knowledgefocuses on the structures of these green nanoparticles along with their biomedical potentials. It is interesting to note how a variety of structures are generated by using resources like microbes or plants or plant products and how the structure affects their activities. This study might pave the way for further development in this arena and future work may be taken up in identifying the detailed mechanism by which 'green' synthesis empowers nanoparticles to kill pathogenic microbes.

Silver Nanoparticles Synthesized by Using the Endophytic Bacterium Pantoea ananatis are Promising Antimicrobial Agents against Multidrug Resistant Bacteria

Antibiotic resistance is one of the most important global problems currently confronting the world. Different biomedical applications of silver nanoparticles (AgNPs) have indicated them to be promising antimicrobial agents. In the present study, extracellular extract of an endophytic bacterium, Pantoea ananatis, was used for synthesis of AgNPs. The synthesized AgNPs were characterized by UV⁻Vis spectroscopy, FTIR, transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), and Zeta potential. The antimicrobial potential of the AgNPs against pathogenic Staphylococcus aureus subsp. aureus (ATCC 11632), Bacillus cereus (ATCC 10876), Escherichia coli (ATCC 10536), Pseudomonas aeruginosa (ATCC 10145) and Candida albicans (ATCC 10231), and multidrug resistant (MDR) Streptococcus pneumoniae (ATCC 700677), Enterococcus faecium (ATCC 700221) Staphylococcus aureus (ATCC 33592) Escherichia coli (NCTC 13351) was investigated. The synthesized spherical-shaped AgNPs with a size range of 8.06 nm to 91.32 nm exhibited significant antimicrobial activity at 6 μg/disc concentration against Bacillus cereus (ATCC 10876) and Candida albicans (ATCC 10231) which were found to be resistant to conventional antibiotics. The synthesized AgNPs showed promising antibacterial efficiency at 10 µg/disc concentration against the MDR strains. The present study suggests that AgNPs synthesized by using the endophytic bacterium P. ananatis are promising antimicrobial agent.

Biomedical Applications of Silver Nanoparticles: An Up-to-Date Overview

During the past few years, silver nanoparticles (AgNPs) became one of the most investigated and explored nanotechnology-derived nanostructures, given the fact that nanosilver-based materials proved to have interesting, challenging, and promising characteristics suitable for various biomedical applications. Among modern biomedical potential of AgNPs, tremendous interest is oriented toward the therapeutically enhanced personalized healthcare practice. AgNPs proved to have genuine features and impressive potential for the development of novel antimicrobial agents, drug-delivery formulations, detection and diagnosis platforms, biomaterial and medical device coatings, tissue restoration and regeneration materials, complex healthcare condition strategies, and performance-enhanced therapeutic alternatives. Given the impressive biomedical-related potential applications of AgNPs, impressive efforts were undertaken on understanding the intricate mechanisms of their biological interactions and possible toxic effects. Within this review, we focused on the latest data regarding the biomedical use of AgNP-based nanostructures, including aspects related to their potential toxicity, unique physiochemical properties, and biofunctional behaviors, discussing herein the intrinsic anti-inflammatory, antibacterial, antiviral, and antifungal activities of silver-based nanostructures.