Review on Green Synthesis of Silver Nanoparticles through Plants

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.

Biogenic Synthesis, Characterization, and In Vitro Biological Evaluation of Silver Nanoparticles Using Cleome brachycarpa

The therapeutical attributes of silver nanoparticles (Ag-NPs) in both conditions (in vitro and in vivo) have been investigated using different plants. This study focused on the green chemistry approach that was employed to optimize the synthesis of silver nanoparticles (AgNPs) using Cleome brachycarpa aqueous extract as a reducing and stabilizing agent. The characterization of obtained CB-AgNPs was undertaken using UV-visible spectroscopy, Atomic-force microscopy (AFM), Fourier-Transform Infrared Spectroscopy (FTIR), scanning electron microscopy (SEM), and Energy-Dispersive X-ray (EDX) analysis. Results suggest that CB-AgNPs synthesized via stirring produced small-sized particles with more even distribution. The synthesized silver nanoparticles were spherical with a 20 to 80 nm size range. In vitro studies were used to analyze antioxidant, antidiabetic, and cytotoxic potential under different conditions. The results also indicated that CB-AgNPs may have significant potential as an antidiabetic in low concentrations, but also exhibited potential antioxidant activity at different concentrations. Moreover, the anticancer activity against the breast cell line (MCF-7) with IC₅₀ reached up to 18 μg/mL. These results suggest that green synthesized silver nanoparticles provide a promising phytomedicine for the management of diabetes and cancer therapeutics.

Characterization and Therapeutic Applications of Biosynthesized Silver Nanoparticles Using Cassia auriculate Flower Extract

The current study analyzes the biosynthesis of silver nanoparticles using the Cassia auriculate flower extract as the reducing and stabilizing agent. The Cassia auriculate- silver nanoparticles (Ca-AgNPs) obtained are characterized by UV-Vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analysis. The results of the spectral characterization have revealed that the surface Plasmon resonance band observed at 448 nm confirms the formation of AgNPs. TEM analysis of the Ca-AgNPs was a predominately spherical shape with a size assortment of 30 to 80 nm and an angular size of 50 nm. The well-analyzed Ca-AgNPs were used in various biological assays, including healthcare analysis of antimicrobial, antioxidant (DPPH), and cytotoxic investigations. Ca-AgNPs showed efficient free radical scavenging activity and showed excellent antimicrobial activity against to pathogenic strains. The occurrence of Ca-AgNPs lead to reduced Live/Dead ratio of bacteria (from 36.97 ± 1.35 to 9.43 ± 0.27) but improved the accumulation of bacterial clusters. The cytotoxicity of Ca-AgNPs was carried out by MTT assay against MCF-7 breast cancer cells and a moderate cytotoxic. The approach of flower extract-mediated synthesis is a cost-efficient, eco-friendly, and easy alternative to conventional methods of silver nanoparticle synthesis.

Synthesis of Green Engineered Silver Nanoparticles through Urtica dioica: An Inhibition of Microbes and Alleviation of Cellular and Organismal Toxicity in Drosophila melanogaster

Plant fractions have a diversity of biomolecules that can be used to make complicated reactions for the bioactive fabrication of metal nanoparticles (NPs), in addition to being beneficial as antioxidant medications or dietary supplements. The current study shows that Urtica dioica (UD) and biologically synthesized silver nanoparticles (AgNPs) of UD have antibacterial and antioxidant properties against bacteria (Escherichia coli and Pseudomonas putida) and Drosophila melanogaster (Oregon R+). According to their ability to scavenge free radicals, DPPH, ABTS, TFC, and TPC initially estimated the antioxidant potential of UD and UD AgNPs. The fabricated AgNPs were analyzed (UV−Vis, FTIR, EDS, and SEM) to determine the functional groups (alcohol, carboxylic acids, phenol, proteins, and aldehydes) and to observe the shape (agglomerated crystalline and rod-shaped structure). The disc diffusion method was used to test the antimicrobial properties of synthesized Ag-NPs against E. coli and P. putida. For 24 to 120 h, newly enclosed flies and third instar larvae of Drosophila were treated with UD and UD AgNPs. After exposure, tests for biochemical effects (acetylcholinesterase inhibition and protein estimation assays), cytotoxicity (dye exclusion), and behavioral effects (jumping and climbing assays) were conducted. The results showed that nanoparticles were found to have potent antimicrobial activity against all microbial strains tested at various concentrations. In this regard, ethno-medicinal characteristics exhibit a similar impact in D. melanogaster, showing (p < 0.05) significantly decreased cellular toxicity (trypan blue dye), enhanced biochemical markers (AChE efficacy and proteotoxicity), and improved behavioral patterns in the organism treated with UD AgNPs, especially in comparison to UD extract. The results of this study may help in the utilization of specific plants as reliable sources of natural antioxidants that may have been beneficial in the synthesis of metallic NPs, which aids in the production of nanomedicine and other therapeutic applications.

Green Synthesis of Silver Nanoparticles Using Spent Coffee Ground Extracts: Process Modelling and Optimization

Large amounts of spent coffee grounds (SCGs) are produced annually worldwide. SCGs contain high levels of phenolics and other bioactive compounds that make them a potential source of reducing and stabilizing agents for the synthesis of metal nanoparticles. This study investigates the use of SCG extracts as a green strategy to produce silver nanoparticles (AgNPs). SCG extracts were obtained using aqueous ethanol as the solvent and then contacted with a silver nitrate solution under the selected conditions. A central composite design coupled with response surface methodology was used to evaluate the effects of solvent composition (C = 30–70% v/v), silver-to-phenolic ratio (R = 3–7 mol/mol), temperature (T = 25–55 °C) and pH (10–12) on the production of AgNPs. Characterization of AgNPs by DLS, TEM and XRD techniques showed that they were highly crystalline with a narrow size distribution. Under optimal reaction conditions, AgNPs with an average size of about 10 nm and a zeta potential of −30.5 to −20.7 mV were obtained. Overall, the results of this study indicate that SCGs are a promising material for the green synthesis of small-sized and stable AgNPs.

Green nanoparticles as multifunctional nanomedicines: Insights into anti-inflammatory effects, growth signaling and apoptosis mechanism in cancer

Recently, green nanotechnology got great attention due to their reliable, sustainable, and eco-friendly synthesis protocols. The green nanoparticles (GNPs) are preferred over chemically synthesized nanoparticles owing to less destructive effects associated with the synthesis procedures as well as therapeutic involvement. In this review, we have discussed the applications of GNPs in inflammation-mediated disorders, with special emphasis on cancer, initiated due to oxidative stress and inflammatory cascade. Real-time mechanism based studies on GNPs have suggested their anticancer effects through inducing apoptosis, inhibiting angiogenesis, tissue invasion metastasis, reduced replicative capabilities in addition to target specific different signaling molecules and cascades involved in the development or progression of cancer. Moreover, the association of GNPs with the inhibition or induction of autophagy for the management of cancer has also been discussed. A large number of studies showed the GNPs have multifunctional biomedical properties of theranostic prominence. Therefore, the development of GNPs with naturally established systems could upsurge their definite applications as biomedicines including target specific destruction of the cancerous cells.

Investigation of Antimicrobial and Cytotoxic Properties and Specification of Silver Nanoparticles (AgNPs) Derived From Cicer arietinum L. Green Leaf Extract

Using biological materials to synthesize metallic nanoparticles has become a frequently preferred method by researchers. This synthesis method is both fast and inexpensive. In this study, an aqueous extract obtained from chickpea (Cicer arietinum L.) (CA) leaves was used in order to synthesize silver nanoparticles (AgNPs). For specification of the synthesized AgNPs, UV-vis spectrophotometer, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), electron dispersive X-ray (EDX), and zeta potential (ZP) analyses data were used. Biologically synthesized AgNPs demonstrated a maximum surface plasmon resonance of 417.47 nm after 3 h. With the powder XRD model, the mean crystallite dimension of nanoparticles was determined as 12.17 mm with a cubic structure. According to the TEM results, the dimensions of the obtained silver nanoparticles were found to be 6.11–9.66 nm. The ZP of the electric charge on the surface of AgNPs was measured as −19.6 mV. The inhibition effect of AgNPs on food pathogen strains and yeast was determined with the minimum inhibition concentration (MIC) method. AgNPs demonstrated highly effective inhibition at low concentrations especially against the growth of B. subtilis (0.0625) and S. aureus (0.125) strains. The cytotoxic effects of silver nanoparticles on cancerous cell lines (CaCo-2, U118, Sk-ov-3) and healthy cell lines (HDF) were revealed. Despite the increase of AgNPs used against cancerous and healthy cell lines, no significant decrease in the percentage of viability was detected.

Green synthesis and antibiofilm potential of Silver Nanoparticles loaded with Narcissus tazetta L. Extract

Bacterial infections are the leading cause of mortality, due to the paucity of effective drugs. This study aimed to synthesize AgNPs loaded with fresh leaves & bulbs extracts of Narcissus tazetta and evaluate antimicrobial and antibiofilm potential against selected bacterial and fungal isolates using standard microbiological protocols. Different techniques like FTIR spectroscopy, GC-MS, electron microscopy and HPLC were used to characterize the AgNPs. The AgNPs synthesized from crude extract of leaves and bulb were checked and were found effective against all the bacterial isolates except E. coli however, strong biofilm inhibition potential was observed in case of E.coli. The synthesized AgNPs showed dose dependent zone of inhibition higher for methanol and lower for n-Hexane against both Gram + ve and Gram -ve bacterial strains, exhibiting the anti-microbial potential. Biofilm inhibition was recorded at sub-MIC values against Gram + ve and Gram -ve bacterial strains. Antifungal activity of AgNPs was observed only at a higher concentration against Aspergillus niger, Fusarium oxysporum and Alternaria alternata while Aspergillus terreus was resistant even at higher concentrations. In conclusion, we can say that the plant possesses pronounced antimicrobial potential with a wide range of the bioactive compounds, which can be explored for pharmaceutical purposes.

Regulatory mechanisms of sub-inhibitory levels antibiotics agent in bacterial virulence

Antibiotics play a key role in the prevention and treatment of bacterial diseases for human and animals. The widespread use of antibiotics results in bacterial exposure to the concentrations that are lower than the MIC (that is, sub-inhibitory concentration (sub-MIC)) in the environment, humans, and livestock, which can lead to antibiotic resistance. In this review, we focus on the impact of sub-MIC antibiotics in bacterial virulence. This paper summarized the known relationships between sub-MIC antibiotics in the environment and bacterial virulence. Together, considering the impact of sub-MIC antibiotics and their alternative products in the virulence of bacteria, it is helpful to the rational use of antibiotics and the development of antibiotic alternative products to provide new insights.Key points• Sub-MIC level antibiotics exist in the environment, humans, and livestock.• The review includes mechanisms of sub-MIC antibiotics in bacterial virulence.• New antibacterial strategies and agents are being a new way to weaken virulence. Graphical Abstract.