A review on plant-mediated synthesis of silver nanoparticles, their characterization and applications

Biogenic biocompatible silver nanoparticles: a promising antibacterial agent

The biogenic synthesis of silver nanoparticles (AgNPs) are gaining attention because they are eco-friendly, non-hazardous, economical and devoid of the drawbacks of physicochemical processes. Biogenic approaches for synthesizing nanoparticles (NPs) using plant leaves, seeds, bark, stems, fruits, roots and flowers are highly cost-effective compared to other methods. Silver (Ag) has been used since ancient times, but biogenic AgNPs have only been made in the last few decades. They have been employed primarily in the food and pharmaceutical industries as antimicrobials and antioxidants. Recent studies have confirmed that many molecules present in different bacteria, including Escherichia coli, Staphylococcus aureus, Citrobacter koseri, Bacillus cereus, Salmonella typhi, Klebsipneumoniaoniae, Vibrio parahaemolyticus, Pseudomonas Aeruginosa, are bound to the AgNPs and can be inhibited using multifaceted mechanisms like AgNPs inter inside the cells, free radicals, ROS generation and modulate transduction pathways. Recent breakthroughs in nanobiotechnology-based therapeutics have opened up new possibilities for fighting microorganisms. Thus, in particular, biogenic AgNPs as powerful antibacterial agents have gained much interest. Surface charge, colloidal state, shape, concentration and size are the most critical physicochemical characteristics that determine the antibacterial potential of AgNPs. Based on this review, it can be stated that AgNPs could be made better in terms of their potency, durability, accuracy, biosecurity and compatibility.

Silver Nanoparticles: Synthesis, Structure, Properties and Applications

Silver nanoparticles (Ag NPs) have accumulated significant interest due to their exceptional physicochemical properties and remarkable applications in biomedicine, electronics, and catalysis sensing. This comprehensive review provides an in-depth study of synthetic approaches such as biological synthesis, chemical synthesis, and physical synthesis with a detailed overview of their sub-methodologies, highlighting advantages and disadvantages. Additionally, structural properties affected by synthesis methods are discussed in detail by examining the dimensions and surface morphology. The review explores the distinctive properties of Ag NPs, including optical, electrical, catalytic, and antimicrobial properties, which render them beneficial for a range of applications. Furthermore, this review describes the diverse applications in several fields, such as medicine, environmental science, electronics, and optoelectronics. However, with numerous applications, several kinds of issues still exist. Future attempts need to address difficulties regarding synthetic techniques, environmental friendliness, and affordability. In order to ensure the secure utilization of Ag NPs, it is necessary to establish sustainability in synthetic techniques and eco-friendly production methods. This review aims to give a comprehensive overview of the synthesis, structural analysis, properties, and multifaceted applications of Ag NPs.

Study of MIC of silver and zinc oxide nanoparticles, strong and cost-effective antibacterial against biofilm-producing Acinetobacter baumannii in Shiraz, Southwest of Iran

BACKGROUND

Acinetobacter baumannii resistant strains lead to increased mortality, treatment costs, and an increase in the length of hospitalization. Nowadays, nanoparticles are considered a substitute for antibiotics. This study aimed to determine the MIC of Silver (Ag) and Zinc Oxide (ZnO) Nanoparticles (NPs) on Biofilm-Producing Acinetobacter baumannii and determine the relationship between MIC and frequency of efflux pump genes in cutaneous specimens in Shiraz, Southwest Iran in 2021-2022.

METHODS

In this study, specimens were collected from April 2021 to June 2022 at Namazi and Faqihi Hospitals in Shiraz. Investigation of biofilm production in multidrug resistance (MDR) isolates was done by the microtiter plate method. Synthesized nanoparticles were characterized by UV-vis spectrum, X-ray diffraction (XRD), and electron microscopy. The MIC of AgNPs and ZnONPs for isolates was done using the method described in the CLSI guideline (2018). The antibacterial effect of MIC of NPs on inanimate objects was done by colony counts. The prevalence of efflux pump genes (adeR, adeC, adeA, abeM, adeK, adeI) was also investigated by PCR technique.

RESULTS

The highest ceftriaxone resistance (68%) and lowest colistin resistance (7%) were identified. 57% of isolates were MDR. In addition, 71.9% could produce biofilm and 28.1% of isolates could not produce biofilm. The average size of AgNPs and ZnONPs in the present study is 48 and < 70 nm, respectively. The nanoparticles were spherical. The MIC and the MBC of the ZnONPs were in the range of 125 to 250 µg/mL respectively. Also, for AgNPs, the MIC and the MBC were in the range of 62.5 to 250 µg/ml, respectively. AbeM gene had the highest frequency and the AdeK gene had the lowest frequency. Statistical analysis showed that there is a relationship between the frequency of adeA, adeC, and adeM genes with the MIC of AgNPs and ZnONPs.

CONCLUSION

According to the results of the present study, inanimate objects such as scalpels in contact with AgNPs (6000 µg/ml for 240 min) or ZnONPs (5000 µg/ml for 120 min) can be free of biofilm producing Acinetobacter baumannii  with efflux pump genes.

A systematic review on green synthesis of silver nanoparticles using plants extract and their bio-medical applications

Nanoparticles have recently become considered as a crucial player in contemporary medicine, with therapeutic uses ranging from contrast agents in imaging to carriers for the transport of drugs and genes into a specific target. Nanoparticles have the ability to have more precise molecular interactions with the human body in order to target specific cells and tissues with minimal adverse effects and maximal therapeutic outcomes. With the least number of side effects and the greatest possible therapeutic benefit, nanoparticles can target particular cells and tissues through more precise molecular interactions with the human body. The majority of global public health problems are now treated with green synthesized silver nanoparticles (AgNPs), which substantially affect the fundamental structure of DNA and proteins and thus display their antimicrobial action. AgNPs can inhibit the proliferation of tumor cells and induce oxidative stress. By inhibiting vascular endothelial growth factor (HIF)-1, pro-inflammatory mediators generated by silver nanoparticles are reduced, mucin hypersecretion is lessened, and gene activity is subsequently regulated to prevent infections. The biogenic synthesis of silver nanoparticles (AgNPs) using various plants and their applications in antibacterial, antifungal, antioxidant, anticancer, anti-inflammatory, and antidiabetic activities have been extensively discussed in this article. Also, because only natural substances are utilized in the manufacturing process, the particles that are created naturally are coated, stabilized, and play a vital role in these biomedical actions. The characterization of AgNPs, possibility of preparing AgNPSs with different shapes using biological method and their impact on functions and toxicities, impact of size, shape and other properties on AgNPs functions and toxicity profiles, limitations, and future prospects of green-mediated AgNPs have also been reported in this study. The major goal of this study is to provide readers with a comprehensive, informed, and up-to-date summary of the various AgNPs production and characterization methods and their under-investigational antioxidant, antibacterial, and anticancer, antidiabetic, antifungal and anti-inflammatory properties. This review provides instructions and suggestions for additional studies based on AgNPs. This evaluation also pushes researchers to look into natural resources like plant parts in order to create useful nanobiotechnology.

Evaluation of biological potential of UV-spectrophotometric, SEM, FTIR, and EDS observed Punica granatum and Plectranthus rugosus extract-coated silver nanoparticles: A comparative study

Recent developments in the green synthesis of metallic nanoparticles (NPs) using phytoconstituents have attracted the attention of the global scientific community. The present study was designed to synthesize silver NPs (AgNPs) using Punica granatum and Plectranthus rugosus plant extracts. The fabricated AgNPs were characterized using UV-visible spectrophotometry (UV-Vis), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy-dispersive x-ray spectroscopy (EDS). The shift in the color of the silver nitrate (AgNO3 ) solution after the addition of P. granatum and P. rugosus extracts indicated the synthesis of AgNPs. The effect of AgNO3 concentrations and pH on the synthesis of AgNPs was also evaluated. The findings of this study suggest that AgNO3 concentration of 1 mM, reaction time of 1 h, and pH of 7 at room temperature were the best suited conditions for the synthesis of AgNPs. According to the FTIR analysis, amidic and carbonyl compounds were primarily responsible for the encapsulation of AgNPs. SEM investigations have shown irregularly shaped geometry with sizes of 35 nm (P. granatum) and 33 nm (P. rugosus) with low agglomeration. The prepared AgNPs exhibited good potential for 2,2-diphenyl-1-picrylhydrazyl radical scavenging, with values of 70% (P. granatum) and 68% (P. rugosus). Hence, we conclude that the leaves of P. granatum and P. rugosus are excellent material for designing of different plant-extracted-conjugated AgNPs for biomedical applications. RESEARCH HIGHLIGHTS: Preparation of the AgNPs using novel plants extracts. P. granatum and P. rugosus extract as reducing, capping, stabilizing, and optimizing agents. Thorough comparative characterization using UV-Vis spectrophotometer, FTIR, SEM, and EDS which is a first of its kind. Comparative antioxidant activity.

Therapeutic strategy of biological macromolecules based natural bioactive compounds of diabetes mellitus and future perspectives: A systematic review

High blood glucose levels are a hallmark of the metabolic syndrome known as diabetes mellitus. More than 600 million people will have diabetes by 2045 as the global prevalence of the disease continues to rise. Contemporary antidiabetic drugs reduce hyperglycemia and its consequences. However, these drugs come with undesirable side effects, so it's encouraging that research into plant extracts and bioactive substances with antidiabetic characteristics is on the rise. Natural remedies are preferable to conventional anti-diabetic drugs since they are safer for the body, more affordable and have fewer potential adverse effects. Biological macromolecules such as liposomes, niosomes, polymeric nanoparticles, solid lipid nanoparticles, nanoemulsions and metallic nanoparticles are explored in this review. Current drug restrictions have been addressed, and the effectiveness of plant-based antidiabetic therapies has enhanced the merits of these methods. Plant extracts' loading capacity and the carriers' stability are the primary obstacles in developing plant-based nanocarriers. Hydrophilic, hydrophobic, and amphiphilic drugs are covered, and a brief overview of the amphipathic features of liposomes, phospholipids, and lipid nanocarriers is provided. Metallic nanoparticles' benefits and attendant risks are highlighted to emphasize their efficiency in treating hyperglycemia. Researchers interested in the potential of nanoparticles loaded with plant extracts as antidiabetic therapeutics may find the current helpful review.

Green synthesis of gold and silver nanoparticles using crude extract of Aconitum violaceum and evaluation of their antibacterial, antioxidant and photocatalytic activities

Green synthesis of metal nanoparticles (NPs) has received extensive attention over other conventional approaches due to their non-toxic nature and more biocompatibility. Herein we report gold and silver NPs (AuNPs@AV and AgNPs@AV) prepared by employing a green approach using crude extract of Aconitum violaceum Jacquem. ex Stapf. The synthesized NPs were characterized using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray (EDX), X-ray Diffraction (XRD), UV/Visible spectroscopy, Fourier Transform Infrared (FTIR), X-ray Photoelectron Spectroscopy (XPS), and Zeta Potential. Morphological analysis showed spherical and triangular shapes of the NPs with average size of <100 nm. The AuNPs@AV and AgNPs@AV exhibited effective antibacterial activities, with minimum inhibitory concentrations (MICs) of 95 and 70 μg/mL against Lactobacillus acidophilus (L. acidophilus) and 90 and 65 μg/mL against Escherichia coli (E. coli), respectively. Strong antioxidant effect of AuNPs@AV and AgNPs@AV were reported against DPPH radical and PTIO within range of IC50 values; 161-80 μg/ml as compared to the standard (23-11 μg/mL) respectively. Moreover, the AuNPs@AV and AgNPs@AV showed efficient photocatalytic activity and degraded 89.88% and 93.7% methylene blue (MB) dye under UV light, respectively.

Plant-mediated synthesis of silver nanoparticles: unlocking their pharmacological potential-a comprehensive review

In recent times, nanoparticles have experienced a significant upsurge in popularity, primarily owing to their minute size and their remarkable ability to modify physical, chemical, and biological properties. This burgeoning interest can be attributed to the expanding array of biomedical applications where nanoparticles find utility. These nanoparticles, typically ranging in size from 10 to 100 nm, exhibit diverse shapes, such as spherical, discoidal, and cylindrical configurations. These variations are not solely influenced by the manufacturing processes but are also intricately linked to interactions with surrounding stabilizing agents and initiators. Nanoparticles can be synthesized through physical or chemical methods, yet the biological approach emerges as the most sustainable and eco-friendly alternative among the three. Among the various nanoparticle types, silver nanoparticles have emerged as the most encountered and widely utilized due to their exceptional properties. What makes the synthesis of silver nanoparticles even more appealing is the application of plant-derived sources as reducing agents. This approach not only proves to be cost-effective but also significantly reduces the synthesis time. Notably, silver nanoparticles produced through plant-mediated processes have garnered considerable attention in recent years due to their notable medicinal capabilities. This comprehensive review primarily delves into the diverse medicinal attributes of silver nanoparticles synthesized using plant-mediated techniques. Encompassing antimicrobial properties, cytotoxicity, wound healing, larvicidal effects, anti-angiogenesis activity, antioxidant potential, and antiplasmodial activity, the paper extensively covers these multifaceted roles. Additionally, an endeavor is made to provide an elucidated summary of the operational mechanisms underlying the pharmacological actions of silver nanoparticles.

Mass production of morin-stabilized silver nanoparticles: Characterization, antioxidant, and antimicrobial activities

Phytochemical-conjugated silver nanoparticles (AgNPs) are believed to act as a bridge between nanotechnology and therapy. There is a significant need for green and mass production of such materials due to their extensive applications, especially in the biomedical sector. In this study, morin-stabilized silver nanoparticles (morin/AgNPs) were synthesized on a massive scale using a one-pot solid-state technique. The reaction is achieved by ball milling of morin and silver nitrate powders at ambient temperature without any solvent or toxic reagent. The prepared morin/AgNPs exhibited a semi-hexagonal shape and ranged in size from 21 to 43 nm. The x-ray diffraction results elucidated the formation of highly crystalline AgNPs. Fourier transform infrared and x-ray photoelectron spectroscopic analyses prove that the hydroxyl, carbonyl, and aromatic functionalities in morin are playing major roles in the reduction and stabilization of AgNPs. The antioxidant potential of morin/AgNPs was evaluated utilizing 2,2-Diphenyl-1-picryl-hydrazyl (DPPH) assay. Morin/AgNPs exhibited better free radical scavenging activity (IC50  = 11.7 μg/mL) than morin (IC50  = 14.8 μg/mL). Furthermore, the synthesized AgNPs showed promising antimicrobial activity against Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, Streptococcus mutans, and Candida albicans. The largest inhibition zones were observed against S. aureus (21.2 ± 0.6 mm) and K. pneumonia (20.3 ± 0.5 mm) bacteria. The foregoing results highlighted the prospective application of morin/AgNPs as a promising antioxidant and antimicrobial material for safe medical applications. RESEARCH HIGHLIGHTS: A simple green route for the large-scale production of AgNPs was developed. Morin acts as reducing/stabilizing agent in solid-state synthesis of AgNPs. Morin/AgNPs exhibited promising antimicrobial and antioxidant activity.

Green Synthesized Iron-Coated Silver Nanoparticles: Economic Bimetallic Nanoparticles Potential Against Methicillin-Resistance Staphylococcus aureus

Iron coating was introduced as one of the novel techniques to improve physicochemical and biological properties of silver nanoparticles (AgNPs). In the current experiment, impact of iron coating on the antimicrobial potency of AgNPs was investigated against methicillin-resistance Staphylococcus aureus (MRSA). To obtain more accurate data about the antimicrobial potency of examined nanostructures, the experiment was done on the 10 isolates of MRSA which were isolated from skin lesions. AgNPs and iron-coated AgNPs (Fe@AgNPs) were fabricated based on a green one-pot reaction procedure. Minimal inhibitory concentration (MIC) of Fe@AgNPs was not significantly different with MIC of AgNPs against eight out of 10 examined MRSA isolates. Also, by iron coating a reduction in the minimal inhibitory concentration (MIC) of AgNPs was observed against two MRSA isolates. The average MIC of AgNPs against 10 MRSA isolates was calculated to be 2.16 ± 0.382 mg/mL and this value was reduced to 1.70 ± 0.638 mg/mL for Fe@AgNPs. However, this difference was not considered significant statistically (P-value > 0.05). From productivity point of view, it was found that iron coating would improve the productivity of the synthesis reaction more than fivefold. Productivity of AgNPs was calculated to be 1.02 ± 0.07 g/L, meanwhile this value was 5.25 ± 0.05 g/L for Fe@AgNPs. Iron coating may provide another economic benefit to reduce final price of AgNPs. It is obvious that the price of a particular nanostructure made of silver and iron is significantly lower than that of pure silver. These findings can be considered for the fabrication of economic and potent antimicrobial nanoparticles.

Rotheca serrata Flower Bud Extract Mediated Bio-Friendly Preparation of Silver Nanoparticles: Their Characterizations, Anticancer, and Apoptosis Inducing Ability against Pancreatic Ductal Adenocarcinoma Cell Line

Over past decades, the green method of synthesizing metal nanoparticles has acquired more attentiveness by scientific consensus because of its industrial and biomedical applications. This study focuses on the anti-proliferative effectiveness of AgNPs synthesized from Rotheca serrata (L.) Steane & Mabb. flower bud extract against the PANC-1 cell line in vitro. Various analytical instruments were utilized to visualize the formation of RsFb-AgNPs, such as UV-Vis spectroscopy, FT-IR, SEM, EDS, TEM, XRD, Zeta potential, and DLS analysis. The biosynthesis of RsFb-AgNPs was observed by a change in color and UV-Vis spectroscopy (415 nm). The FT-IR spectra exhibited the existence of many functional groups. XRD confirmed the crystallinity of the AgNPs. Morphology and elemental mapping were assessed by SEM and EDS analysis. The TEM micrograph revealed spherical-shaped particles with sizes ranging from 12 to 40 nm. Zeta potential and DLS analysis were used to measure surface charge and particle size. Biological properties, including the antioxidant, antimicrobial, and anticancer properties of synthesized RsFb-AgNPs, exhibited dose-dependent activities. In DPPH assay, synthesized RsFb-AgNPs inhibited the scavenging of free radicals in a dose-dependent manner. In addition, the resultant RsFb-AgNPs displayed moderate antimicrobial activity against tested pathogens. Further, the anti-proliferative efficacy of biosynthesized RsFb-AgNPs was determined against the PANC-1 cell line using the MTT assay. The results revealed a dose-dependent decrease in viability of cancer cells with an IC50 value of 36.01 µg/mL. Flow cytometry was then used to confirm the apoptotic effects by double staining with annexin V/PI. In response to the pancreatic ductal adenocarinoma cell line, the results showed notable early and late apoptosis cell population percentages. In conclusion, the synthesized RsFb-AgNPs revealed a potential anticancer agent that can induce apoptosis in the PANC-1 cells.

Leonotis nepetifolia Flower Bud Extract Mediated Green Synthesis of Silver Nanoparticles, Their Characterization, and In Vitro Evaluation of Biological Applications

Biosynthesis of silver nanoparticles (AgNPs) using the green matrix is an emerging trend and is considered green nanotechnology because it involves a simple, low-cost, and environmentally friendly process. The present research aimed to synthesize silver nanoparticles from a Leonotis nepetifolia (L.) R.Br. flower bud aqueous extract, characterize these nanoparticles, and perform in vitro determination of their biological applications. UV-Vis spectra were used to study the characterization of biosynthesized L. nepetifolia-flower-bud-mediated AgNPs (LnFb-AgNPs); an SPR absorption maximum at 418 nm confirmed the formation of LnFb-AgNPs. The presumed phytoconstituents subjected to reduction in the silver ions were revealed by FTIR analysis. XRD, TEM, EDS, TGA, and zeta potential with DLS analysis revealed the crystalline nature, particle size, elemental details, surface charge, thermal stability, and spherical shape, with an average size of 24.50 nm. In addition, the LnFb-AgNPs were also tested for antimicrobial activity and exhibited a moderate zone of inhibition against the selected pathogens. Concentration-dependent antioxidant activity was observed in the DPPH assay. Further, the cytotoxicity increased proportionate to the increasing concentration of the biosynthesized LnFb-AgNPs with a maximum effect at 200 μg/mL by showing the inhibition cell viability percentages and an IC₅₀ of 35.84 μg/mL. Subsequently, the apoptotic/necrotic potential was determined using Annexin V/Propidium Iodide staining by the flow cytometry method. Significant early and late apoptosis cell populations were observed in response to the pancreatic ductal adenocarcinoma (PANC-1) cell line, as demonstrated by the obtained results. In conclusion, the study's findings suggest that the LnFb-AgNPs could serve as remedial agents in a wide range of biomedical applications.

Leucophyllum frutescens mediated synthesis of silver and gold nanoparticles for catalytic dye degradation

The application of nanotechnology is gaining worldwide attention due to attractive physico-chemical and opto-electronic properties of nanoparticles that can be also employed for catalytic dye degradation. This study reports a phytogenic approach for fabrication of silver (AgNPs) and gold nanoparticles (AuNPs) using Leucophyllum frutescens (Berl.) I. M. Johnst (Scrophulariaceae) leaf extract (LFLE). Development of intense dark brown and purple color indicated the synthesis of AgNPs and AuNPs, respectively. Further characterization using UV-visible spectroscopy revealed sharp peak at 460 nm and 540 nm for AgNPs and AuNPs, respectively that were associated to their surface plasmon resonance. High resolution transmission electron microscope (HRTEM) revealed the spherical shape of the AgNPs, whereas anisotropic AuNPs were spherical, triangular and blunt ended hexagons. The majority of the spherical AgNPs and AuNPs were ∼50 ± 15 nm and ∼22 ± 20 nm, respectively. Various reaction parameters such as, metal salt concentration, temperature and concentration of the leaf extract were optimized. Maximum synthesis of AgNPs was obtained when 5 mM for AgNO₃ reacted with 10% LFLE for 48 h at 50°C. Likewise, AuNPs synthesis was highest when 2 mM HAuCl₄ reacted with 10% LFLE for 5 h at 30°C. Energy dispersive spectroscopy (EDS) showed phase purity of both the nanoparticles and confirmed elemental silver and gold in AgNPs and AuNPs, respectively. The average hydrodynamic particles size of AgNPs was 34.8 nm while AuNPs was 140.8 nm as revealed using dynamic light scattering (DLS) that might be due to agglomeration of smaller nanoparticles into larger clusters. ZETA potential of AgNPs and AuNPs were 0.67 mV and 5.70 mV, respectively. X-ray diffraction (XRD) analysis confirmed the crystallinity of the nanoparticles. Fourier transform infrared spectroscopy (FTIR) confirmed that various functional groups from the phytochemicals present in LFLE played a significant role in reduction and stabilization during the biogenic synthesis of the nanoparticles. The bioreduced AgNPs and AuNPs catalytically degraded Rhodamine B dye (RhB) in presence of UV-light with degradation rate constants of 0.0231 s⁻¹ and 0.00831 s⁻¹, respectively. RhB degradation followed a first order rate kinetics with 23.1 % and 31.7% degradation by AgNPs and AuNPs, respectively.

Fitting Procedure to Reconstruct the Size Distribution and the Concentration of Silver Colloidal Nanoparticles from UV-Vis Spectra

In this work, a complete fitting procedure of UV-Vis spectra of silver nanoparticles in colloidal solutions is reported. The fitting function, based on the Beer-Lambert law, Mie theory, and log-normal probability distribution of nanoparticles' sizes, is developed and confirmed by 33 different independent measurements. In order to validate the accuracy of the function's behavior on different spectra, freely accessible measurements were used, proving that the fitting function works independently of the method of their production-laser or chemical synthesis of nanoparticles. The developed fitting function is, to the best of our knowledge, novel and not based on any conventional spectral analysis approaches like the Mie-Gans procedure. Furthermore, since fitted parameters are all physical, it allows determination of the mode diameter of nanoparticles as well as the standard deviation of the log-normal distribution of sizes. It enables the reconstruction of size distribution of nanoparticles in colloidal solution. Step-by-step derivation of the fitting function is provided with a physical explanation of all parameters. The importance of Lorentzian dependence emerging at the core of Beer-Lambert law is physically discussed and linked to harmonic oscillator behavior of localized surface plasmon resonance of silver nanoparticles in a colloidal solution. Size distribution reconstruction from fitted parameters according to a log-normal distribution function is provided and a concentration calculation is presented.

Photocatalytic Activity Induced by Metal Nanoparticles Synthesized by Sustainable Approaches: A Comprehensive Review

Nanotechnology is a fast-expanding area with a wide range of applications in science, engineering, health, pharmacy, and other fields. Among many techniques that are employed toward the production of nanoparticles, synthesis using green technologies is the simplest and environment friendly. Nanoparticles produced from plant extracts have become a very popular subject of study in recent decades due to their diverse advantages such as low-cost synthesis, product stability, and ecofriendly protocols. These merits have prompted the development of nanoparticles from a variety of sources, including bacteria, fungi, algae, proteins, enzymes, etc., allowing for large-scale production with minimal contamination. However, nanoparticles obtained from plant extracts and phytochemicals exhibit greater reduction and stabilization and hence have proven the diversity of properties, like catalyst/photocatalyst, magnetic, antibacterial, cytotoxicity, circulating tumor deoxy ribo nucleic acid (CT-DNA) binding, gas sensing, etc. In the current scenario, nanoparticles can also play a critical role in cleaning wastewater and making it viable for a variety of operations. Nano-sized photocatalysts have a great scope toward the removal of large pollutants like organic dyes, heavy metals, and pesticides in an eco-friendly and sustainable manner from industrial effluents. Thus, in this review article, we discuss the synthesis of several metal nanoparticles using diverse plant extracts, as well as their characterization via techniques like UV–vis (ultraviolet–visible), XRD (X-ray diffraction), SEM (scanning electron microscopy), TEM (transmission electron microscopy), FTIR (Fourier transform infrared spectroscopy), etc., and catalytic activity on various hazardous systems.

Green Synthesis of Silver Nanoparticles Using Populi gemmae Extract: Preparation, Physicochemical Characterization, Antimicrobial Potential and In Vitro Antiproliferative Assessment

Green route is an economic, facile and eco-friendly method, employed for the synthesis of various types of nanoparticles, having it as a starting point biological entity, especially as a plant extract. The present study aims to obtain silver nanoparticles (AgNPs) starting from an ethanolic extract of Populi gemmae (Pg), by adjusting the reaction parameters. The morphological and structural characterization exhibited that both the reaction temperature and the concentration of metal salt, contributes to the obtaining of Pg-AgNPs with adjustable size and shape. The newly synthesized nanoparticles exhibited a good antibacterial activity on Gram-positive bacteria as well as antifungal activity. The in vitro antiproliferative activity of Pg-AgNPs was assessed on two different cancer cell lines (breast cancer cells-MCF7 and lung carcinoma epithelial cells-A549). Results have shown that the green-synthetized Pg-AgNPs_S2 (obtained at 60 °C, using AgNO3 of 5 M) induced a substantial decrease in tumor cell viability in a dose-dependent manner with an IC50 ranging from 5.03 to 5.07 µg/mL on A549 cell line and 3.24 to 4.93 µg/mL on MCF7 cell line.

Therapeutic potential of biogenic and optimized silver nanoparticles using Rubia cordifolia L. leaf extract

Rubia cordifolia L. is a widely used traditional medicine in the Indian sub-continent and Eastern Asia. In the present study, the aqueous leaf extract of the R. Cordifolia was used to fabricate silver nanoparticles (RC@AgNPs), following a green synthesis approach. Effect of temperature (60 °C), pH (8), as well the concentration of leaf extract (2 ml) and silver nitrate (2 mM) were optimized for the synthesis of stable RC@AgNPs. The phytofabrication of nanosilver was validated by UV–visible spectral analysis, which displayed a distinctive surface plasmon resonance peak at 432 nm. The effective functional molecules as capping and stabilizing agents, and responsible for the conversion of Ag⁺ to nanosilver (Ag⁰) were identified using the FTIR spectra. The spherical RC@AgNPs with an average size of ~ 20.98 nm, crystalline nature, and 61% elemental composition were revealed by TEM, SEM, XRD, and. EDX. Biogenic RC@AgNPs displayed a remarkable anticancer activity against B16F10 (melanoma) and A431 (carcinoma) cell lines with respective IC₅₀ of 36.63 and 54.09 µg/mL, respectively. Besides, RC@AgNPs showed strong antifungal activity against aflatoxigenic Aspergillus flavus, DNA-binding properties, and DPPH and ABTS free radical inhibition. The presented research provides a potential therapeutic agent to be utilized in various biomedical applications.