Highly stable AgNPs prepared via a novel green approach for catalytic and photocatalytic removal of biological and non-biological pollutants

Advancing biomedical applications: an in-depth analysis of silver nanoparticles in antimicrobial, anticancer, and wound healing roles

Introduction: Silver nanoparticles (AgNPs) have gained significant attention in biomedical applications due to their unique physicochemical properties. This review focuses on the roles of AgNPs in antimicrobial activity, anticancer therapy, and wound healing, highlighting their potential to address critical health challenges. Methods: A bibliometric analysis was conducted using publications from the Scopus database, covering research from 2002 to 2024. The study included keyword frequency, citation patterns, and authorship networks. Data was curated with Zotero and analyzed using Bibliometrix R and VOSviewer for network visualizations. Results: The study revealed an increasing trend in research on AgNPs, particularly in antimicrobial applications, leading to 8,668 publications. Anticancer and wound healing applications followed, with significant contributions from India and China. The analysis showed a growing focus on "green synthesis" methods, highlighting a shift towards sustainable production. Key findings indicated the effectiveness of AgNPs in combating multidrug-resistant bacteria, inducing apoptosis in cancer cells, and promoting tissue regeneration in wound healing. Discussion: The widespread research and applications of AgNPs underscore their versatility in medical interventions. The study emphasizes the need for sustainable synthesis methods and highlights the potential risks, such as long-term toxicity and environmental impacts. Future research should focus on optimizing AgNP formulations for clinical use and further understanding their mechanisms of action. Conclusion: AgNPs play a pivotal role in modern medicine, particularly in addressing antimicrobial resistance, cancer treatment, and wound management. Ongoing research and international collaboration are crucial for advancing the safe and effective use of AgNPs in healthcare.

Harnessing nature's potential: Alpinia galanga methanolic extract mediated green synthesis of silver nanoparticle, characterization and evaluation of anti-neoplastic activity

With the advent of nanotechnology, the treatment of cancer is changing from a conventional to a nanoparticle-based approach. Thus, developing nanoparticles to treat cancer is an area of immense importance. We prepared silver nanoparticles (AgNPs) from methanolic extract of Alpinia galanga rhizome and characterized them by UV-Vis spectrophotometry, Fourier transform Infrared (FTIR) spectroscopy, Zetasizer, and Transmission electron Microscopy (TEM). UV-Vis spectrophotometry absorption spectrum showed surface plasmon between 400 and 480 nm. FTIR spectrum analysis implies that various phytochemicals/secondary metabolites are involved in the reduction, caping, and stabilization of AgNPs. The Zetasier result suggests that the particles formed are small in size with a low polydispersity index (PDI), suggesting a narrow range of particle distribution. The TEM image suggests that the particles formed are mostly of spherical morphology with nearly 20-25 nm. Further, the selected area electron diffraction (SAED) image showed five electron diffraction rings, suggesting the polycrystalline nature of the particles. The nanoparticles showed high anticancer efficacy against cervical cancer (SiHa) cell lines. The nanostructures showed dose-dependent inhibition with 40% killing observed at 6.25 µg/mL dose. The study showed an eco-friendly and cost-effective approach to the synthesis of AgNPs and provided insight into the development of antioxidant and anticancer agents.

Recent progress in tannin and lignin blended metal oxides and metal sulfides as smart materials for electrochemical sensor applications

Our technologically advanced civilization has made sensors an essential component. They have potential uses in the pharmaceutical sector, clinical analysis, food quality control, environmental monitoring, and other areas. One of the most active fields of analytical chemistry research is the fabrication of electrochemical sensors. An intriguing area of electroanalytical chemistry is the modification of electrodes using polymeric films. Due to their benefits, which include high adhesion to the electrode surface, chemical stability of the coating, superior selectivity, sensitivity, and homogeneity in electrochemical deposition, polymer-modified electrodes have attracted a great deal of interest in the electroanalytical sector. Conducting polymers are an important material for sensing devices because of their fascinating features, which include high mechanical flexibility, electrical conductivity, and the capacity to be electrochemically converted between electronically insulating and conducting states. Tannin or lignin nanomaterials can be an inter-linker leading to flexible and functional polymeric networks. There is a continuing demand for fast and simple analytical methods for the determination of many clinically important biomarkers, food additives, environmental pollutants etc. This review in a comprehensive way summarizes and discusses the various metal oxide and sulfide-incorporated tannin and lignin scaffolds using electrochemical sensing and biosensing.

Unleashing the promise of emerging nanomaterials as a sustainable platform to mitigate antimicrobial resistance

The emergence and spread of antibiotic-resistant (AR) bacterial strains and biofilm-associated diseases have heightened concerns about exploring alternative bactericidal methods. The WHO estimates that at least 700 000 deaths yearly are attributable to antimicrobial resistance, and that number could increase to 10 million annual deaths by 2050 if appropriate measures are not taken. Therefore, the increasing threat of AR bacteria and biofilm-related infections has created an urgent demand for scientific research to identify novel antimicrobial therapies. Nanomaterials (NMs) have emerged as a promising alternative due to their unique physicochemical properties, and ongoing research holds great promise for developing effective NMs-based treatments for bacterial and viral infections. This review aims to provide an in-depth analysis of NMs based mechanisms combat bacterial infections, particularly those caused by acquired antibiotic resistance. Furthermore, this review examines NMs design features and attributes that can be optimized to enhance their efficacy as antimicrobial agents. In addition, plant-based NMs have emerged as promising alternatives to traditional antibiotics for treating multidrug-resistant bacterial infections due to their reduced toxicity compared to other NMs. The potential of plant mediated NMs for preventing AR is also discussed. Overall, this review emphasizes the importance of understanding the properties and mechanisms of NMs for the development of effective strategies against antibiotic-resistant bacteria.

Endophytic Aspergillus hiratsukae mediated biosynthesis of silver nanoparticles and their antimicrobial and photocatalytic activities

In the current study, endophytic Aspergillus hiratsukae was used for the biosynthesis of silver nanoparticles (Ag-NPs) for the first time. The characterizations were performed using X ray diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), Dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), and UV-Vis spectroscopy. The obtained results demonstrated the successful formation of crystalline, spherical Ag-NPs with particle diameters ranging from 16 to 31 nm. The FT-IR studied and displayed the various functional groups involved, which played a role in capping and reducing agents for Ag-NPs production. The SEM-EDX revealed that the main constituent of the AS-formed sample was primarily Ag, with a weight percentage of 64.2%. The mycosynthesized Ag-NPs were assessed for antimicrobial as well as photocatalytic activities. The antimicrobial results indicated that the synthesized Ag-NPs possess notable antibacterial efficacy against Staphylococcus aureus, Bacillus subtilis, and Escherichia coli, with minimum inhibitory concentrations (MICs) of Ag-NPs ranging from 62.5 to 250 μg/mL. Moreover, the biosynthesized Ag-NPs demonstrated weak antifungal activity against Aspergillus brasiliensis and Candida albicans, with MICs of 500 and 1,000 μg/mL, respectively. In addition, the mycosynthesized Ag-NPs exhibited photocatalytic activity toward acid black 2 (nigrosine) dye under both light and dark stimulation. Notably, After 300 min exposure to light, the nigrosine dye was degraded by 93%. In contrast, 51% degradation was observed after 300 min in darkness. In conclusion, Ag-NPs were successfully biosynthesized using endophytic A. hiratsukae and also exhibited antimicrobial and photocatalytic activities that can be used in environmental applications.

Valorization of plant by-products in the biosynthesis of silver nanoparticles with antimicrobial and catalytic properties

Biosynthesis based on natural compounds has emerged as a sustainable approach for the production of metallic nanoparticles (MNP). The main objective of this study was to biosynthesize stable and multifunctional silver nanoparticles (AgNP) using different plant by-products as reducers and capping agents. Extracts obtained from Eucalyptus globulus, Pinus pinaster, Citrus sinensis, Cedrus atlantica and Camellia sinensis by-products, were evaluated. From all plant by-products tested, aqueous extract of eucalyptus leaves (EL), green tea (GT) and black tea (BT) were selected due to their higher antioxidant phenolic content and were individually employed as reducers and capping agents to biosynthesize AgNP. The green AgNP showed zeta potential values of -31.8 to -36.3 mV, with a wide range of particle sizes (40.6 to 86.4 nm), depending on the plant extract used. Green AgNP exhibited an inhibitory effect against various pathogenic bacteria, including Gram-negative (P. putida, E. coli, Vibrio spp.) and Gram-positive (B. megaterium, S. aureus, S. equisimilis) bacteria with EL-AgNP being the nanostructure with the greatest antimicrobial action. EL-AgNP showed an excellent photodegradation of indigo carmine (IC) dye under direct sunlight, with a removal percentage of up to 100% after 75 min. A complete cost analysis revealed a competitive total cost range of 8.0-9.0 €/g for the biosynthesis of AgNP.

Effects of silver nanoparticles prepared by aqueous extract of Ferula communis on the developing mouse embryo after maternal exposure

Green synthesis of silver nanoparticles (AgNPs) from aqueous silver nitrate has been achieved using an extract of Ferula communis leaf as a capping, reducing, and stabilizing agent. The formation and stability of the green synthesized silver nanoparticles in the colloidal solution were monitored by absorption measurements. Silver nanoparticles were characterized by different analyses such as X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and FT-IR spectroscopy. The average particle size of silver nanoparticles was determined by high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) analyses. In this experiment, pregnant female mice were divided into four groups (G); G1 was the control and received phosphate-buffered saline, G2 received orally aqueous extract of F. communis leaf, G3 received orally AgNPs chemically prepared by NaBH4, and G4 received orally AgNPs prepared by aqueous extract of F. communis leaf. The diameter of AgNPs was 20 nm. AgNPs exhibited good catalytic reduction ability toward methyl orange in the presence of sodium borohydride with a rate constant of 2.95 x 10-4 s-1. The results revealed the occurrence of resorbed embryos in G2, G3, and G4 with different percentages. The livers of mothers and embryos at E14.5 in G2, G3, and G4 showed different levels of histopathological alteration and increase in GFAP and CTGF expressions compared with the control group. The study concluded that the oral administration of small-sized AgNPs (20 nm) prepared by Ferula extract had less toxicity than those prepared by the chemical method.

The Green Synthesis of Silver Nanoparticles from Avena fatua Extract: Antifungal Activity against Fusarium oxysporum f.sp. lycopersici

Using plant extracts as eco-friendly reducing and stabilizing agents for the synthesis of nanoparticles has gained significant attention in recent years. The current study explores the green synthesis of silver nanoparticles (AgNPs) using the Avena fatua extract and evaluates their antifungal activity against Fusarium oxysporum f.sp. lycopersici (Fol), a fungal plant pathogen. A green and sustainable approach was adopted to synthesize silver nanoparticles before these nanoparticles were employed for anti-fungal activity. The primary indication that AgNPs had formed was performed using UV-vis spectroscopy, where a strong peak at 425 nm indicated the effective formation of these nanoparticles. The indication of important functional groups acting as reducing and stabilizing agents was conducted using the FTIR study. Additionally, morphological studies were executed via SEM and AFM, which assisted with more effectively analyzing AgNPs. Crystalline behavior and size were estimated using powder XRD, and it was found that AgNPs were highly crystalline, and their size ranged from 5 to 25 nm. Synthesized AgNPs exhibited significant antifungal activity against Fol at a concentration of 40 ppm. Furthermore, the inhibitory index confirmed a positive correlation between increasing AgNPs concentration and exposure duration. This study suggests that the combined phytochemical mycotoxic effect of the plant extract and the smaller size of synthesized AgNPs were responsible for the highest penetrating power to inhibit Fol growth. Moreover, this study highlights the potential of using plant extracts as reducing and capping agents for the green synthesis of AgNPs with antifungal properties. The study concludes that A. fatua extract can synthesize antifungal AgNPs as a sustainable approach with robust antifungal efficacy against Fol, underscoring their promising potential for integration into plant protection strategies.

Green, facile and fast synthesis of silver nanoparticles by using solution plasma techniques and their antibacterial and anticancer activities

We herein present a simple, fast, efficient and environmentally friendly method for preparing silver nanoparticles (AgNPs) using the solution plasma method in the presence of extracts from Paramignya trimera (P. trimera). The effects of P. trimera extract concentrations and the applied voltage on the formation of AgNPs were investigated. Surface plasmon resonance spectra show a strong peak at 413 nm for the prepared samples. The Fourier-transform infrared spectroscopy measurement results indicated the presence of possible functional groups in the prepared AgNPs. Morphological analysis revealed that the AgNPs were spherical with an average size of 8 nm. The prepared AgNPs exhibited good stability in solution compared to that of AgNPs prepared by the solution plasma technique without P. trimera extract. The formation mechanism of AgNPs is also proposed. The prepared AgNPs exhibited high antibacterial ability against Gram (+) Staphylococcus aureus, Gram (-) Pseudomonas aeruginosa bacteria and strong anticancer activity for the AGS gastric cancer cell line. The obtained results demonstrated that this is a simple, rapid, environmentally friendly method for preparing AgNPs instead of conventional methods using chemical reducing agents for potential applications.

Biosynthesis approach of copper nanoparticles, physicochemical characterization, cefixime wastewater treatment, and antibacterial activities

The aim of this paper is the green synthesis of copper nanoparticles (Cu NPs) via Quinoa seed extract. X-ray diffraction (XRD) results confirmed the production of the pure crystalline face center cubic system of the Cu NPs with an average crystallite size of 8.41 nm. Infrared spectroscopy (FT-IR) analysis confirmed the capping and stabilization of the Cu NPs bioreduction process. UV visible spectroscopy (UV-Vis). surface plasmon resonance revealed the absorption peak at 324 nm with an energy bandgap of 3.47 eV. Electrical conductivity was conducted assuring the semiconductor nature of the biosynthesized Cu NPs. Morphological analysis was investigated confirming the nano-characteristic properties of the Cu NPs as polycrystalline cubic agglomerated shapes in scanning electron microscopy (SEM) analysis. Transmission electron microscopy (TEM) analysis also was used to assess the cubic shapes at a particle size of 15.1 ± 8.3 nm and a crystallinity index about equal to 2.0. Energy dispersive spectroscopy (EDX) was conducted to investigate the elemental composition of the Cu NPs. As a potential utility of the biosynthesized Cu NPs as nano adsorbents to the removal of the Cefixime (Xim) from the pharmaceutical wastewater; adsorption studies and process parameters were being investigated. The following strategic methodology for maximum Xim removal was conducted to be solution pH 4, Cu NPs dosage 30 mg, Xim concentration 100 mg/L, and absolute temperature 313 K. The maximum monolayer adsorption capacity was 122.9 mg/g according to the Langmuir isothermal model, and the kinetic mechanism was pseudo-second-order. Thermodynamic parameters also were derived as spontaneous chemisorption endothermic processes. Antibacterial activity of the Xim and Xim@Cu NPs was investigated confirming they are highly potent against each Gram-negative and Gram-positive bacterium.

Green synthesis of silver nanoparticles mediated Diospyros kaki L. (Persimmon): determination of chemical composition and evaluation of their antimicrobials and anticancer activities

The eco-friendly synthesis of metallic nanoparticles (MNPs) using biological materials is an encouraging and innovativeness approach to nanotechnology. Among other synthesizing methods, biological methods are chosen because of their high efficiency and purity in many aspects. In this work, using the aqueous extract obtained from the green leaves of the D. kaki L. (DK); silver nanoparticles were synthesized in a short time and simply with an eco-friendly approach. The properties of the synthesized silver nanoparticles (AgNPs) were characterized using various techniques and measurements. In the characterization data of AgNPs, Maximum absorbance at 453.34 nm wavelengths, the average size distribution of 27.12 nm, the surface charge of -22.4 mV, and spherical appearance were observed. LC-ESI-MS/MS analysis was used to assess the compound composition of D. kaki leaf extract. The chemical profiling of the crude extract of D. kaki leaves revealed the presence of a variety of phytochemicals, predominantly phenolics, resulting in the identification of five major high-feature compounds: two major phenolic acids (Chlorogenic acid and Cynarin), and tree flavonol glucosides (hyperoside, quercetin-3-glucoside, and quercetin-3- D-xyloside). The components with the highest concentrations were cynarin, chlorogenic acid, quercetin-3- D-xyloside, hyperoside, and quercetin-3-glucoside, respectively. Antimicrobial results were determined by a MIC assay. The biosynthesized AgNPs exhibited strong antibacterial activity against the human and food pathogen Gram (+ and -) bacteria and good antifungal activity against pathogenic yeast. It was determined that 0.03-0.050 μg/mL concentrations ranges of DK-AgNPs were growth suppressive concentrations on all pathogen microorganisms. The MTT technique was used to study the cytotoxic effects of produced AgNPs on cancer cell lines (Glioblastoma (U118), Human Colorectal Adenocarcinoma (Caco-2), Human Ovarian Sarcoma (Skov-3) cancer cell lines, and Human Dermal Fibroblast (HDF) healthy cell line). It has been observed that they have a suppressive effect on the proliferation of cancerous cell lines. After 48 h of treatment with Ag-NPs, the DK-AgNPs were found to be extremely cytotoxic to the CaCo-2 cell line, inhibiting cell viability by up to 59.49% at a concentration of 50 g mL^-1. It was found that the viability was inversely related to the DK-AgNP concentration. The biosynthesized AgNPs had dose-dependent anticancer efficacy. Because of the high concentration of bioactive chemicals in Diospyros kaki, it may be employed as a biological resource in medicinal applications. DK-AgNPs were shown to be an effective antibacterial agent as well as a prospective anticancer agent. The results provide a potential approach for the biogenic production of DK-AgNPs utilizing D. kaki aqueous leaf extract.

Biogenic silver based nanostructures: Synthesis, mechanistic approach and biological applications

The alarming impact of antibiotic resistance sparked the quest for complementary treatments to overcome the confrontation over resistant pathogens. Metallic nanoparticles, especially silver nanoparticles (Ag NPs) have gained a much attention because of their remarkable biological characteristics. Moreover, their medicinal properties can be enhanced by preparing the composites with other materials. This article delves a comprehensive review of biosynthesis route for Ag NPs and their nanocomposites (NCs) with in-depth mechanism, methods and favorable experimental parameters. Comprehensive biological features Ag NPs such as antibacterial, antiviral, antifungal have been examined, with a focus on their potential uses in biomedicine and diagnostics has also been discussed. Additionally, we have also explored the hitches and potential outcomes of biosynthesis of Ag NPs in biomedical filed.

Recent advances in nanomaterials based sustainable approaches for mitigation of emerging organic pollutants

Emerging organic pollutants (EOPs) are a category of pollutants that are relatively new to the environment and recently garnered a lot of attention. The majority of EOPs includes endocrine-disrupting chemicals (EDCs), antibiotic resistance genes (ARGs), pesticides, dyes and pharmaceutical and personal care products (PPCPs). Exposure to contaminated water has been linked to an increase in incidences of malnutrition, intrauterine growth retardation, respiratory illnesses, liver malfunctions, eye and skin diseases, and fatalities. Consequently, there is a critical need for wastewater remediation technologies which are effective, reliable, and economical. Conventional wastewater treatment methods have several shortcomings that can be addressed with the help of nanotechnology. Unique characteristics of nanomaterials (NMs) make them intriguing and efficient alternative in wastewater treatment strategies. This review emphasis on the occurrence of divers emerging organic pollutants (EOPs) in water and their effective elimination via different NMs based methods with in-depth mechanisms. Furthermore, it also delves the toxicity assessment of NMs and critical challenges, which are crucial steps for practical implementations.

Catalytic and antimicrobial potential of green synthesized Au and Au@Ag core-shell nanoparticles

It has been a never-ending quest to design a safe, cost-effective, and environmentally acceptable technology for eliminating contaminants from water and countering antibiotic resistance. Herein, a waste leaf extract from the abundant and renewable plant, Brassica oleracea var. gongylodes, is introduced as a cost-effective and sustainable means to generate gold (Au) and Au@Ag core-shell nanoparticles (NPs). In comparison to the bare Au NPs, bimetallic NPs demonstrated improved catalytic and antibacterial capabilities. The reduction process conforms to the pseudo-first-order kinetic, and apparent rate constant (k_app) was calculated to be 0.46 min^-1, according to the kinetic analysis. With both microbial pathogens, E. coli (Gram-negative) and B. subtilis (Gram-positive), an increment of Au and Au@Ag NPs lead to a considerable improvement in the zone of clearance. The present outcome is a step forward in the establishment of a viable and cost-effective catalytic and antibacterial platform based on bimetallic NPs that could be generated in an inexpensive and eco-friendly manner.

Multi-round recycling of green waste for the production of iron nanoparticles: synthesis, characterization, and prospects in remediation

Due to the widespread applications of metal nanoparticles (NPs), green synthesis strategies have recently advanced, e.g., methods that utilize extracts made from different plant wastes. A particularly innovative approach to reducing large amounts of available household/agricultural green wastes is their application in nanoparticle generation. Regarding this, the aim of our work was to examine the possibility of upgrading green nanoparticle syntheses from an innovative economic and environmental point of view, namely by investigating the multiple recyclabilities of green tea (GT), coffee arabica (CA), and Virginia creeper (Parthenocissus quinquefolia) (VC) waste residues for iron nanoparticle (FeNPs) synthesis. The plant extracts obtained by each extraction round were analyzed individually to determine the amount of main components anticipated to be involved in NPs synthesis. The synthesized FeNPs were characterized by X-ray powder diffraction and transmission electron microscopy. The activity of the generated FeNPs in degrading chlorinated volatile organic compounds (VOC) and thus their future applicability for remediation purposes were also assessed. We have found that VC and especially GT residues could be reutilized in multiple extraction rounds; however, only the first extract of CA was suitable for FeNPs' generation. All of the obtained FeNPs could degrade VOC with efficiencies GT1-Fe 91.0%, GT2-Fe 83.2%, GT3-Fe 68.5%; CA1-Fe 76.2%; VC1-Fe 88.2%, VC2-Fe 79.7%, respectively, where the number (as in GT3) marked the extraction round. These results indicate that the adequately selected green waste material can be reutilized in multiple rounds for nanoparticle synthesis, thus offering a clean, sustainable, straightforward alternative to chemical methods.

ZnO and cobalt decorated ZnO NPs: Synthesis, photocatalysis and antimicrobial applications

The rapid growth of pollutants, both biological and non-biological, puts environmental systems in jeopardy. In view of this, the current study demonstrates the synthesis of undoped and Cobalt-doped zinc oxide nanoparticles (Co doped ZnO NPs) via co-precipitation method. The confirmation of incorporation of the Co dopant into ZnO NPs was verified through various spectroscopic and microscopic techniques. UV-absorption spectra of cobalt-doped ZnO NPs revealed a red shift with change of absorption spectra from 356 nm to 377 nm as compared to undoped ZnO NPs. XRD studies inferred that the average crystallite size of 0.5% and 1% Co-doped ZnO powder was obtained to be ∼16 nm and 14 nm respectively. A drop in band gap value from 3.48 eV to 3.30 eV provided as substantive evidence of the successful integration of Co²⁺ ions inside the ZnO matrix. FESEM and HRTEM studies revealed that the obtained ZnO NPs are in narrow size distribution (15-20 nm) with a wurtzite crystal structure. The synthesized ZnO and Co-ZnO NPs showed excellent photocatalytic and antimicrobial potency towards reactive brown dye (RB-1) and two bacterial strains, respectively. 1% Co-doped ZnO demonstrated the maximum photocatalytic activity (∼95%), in contrast to 0.5% Co-doped ZnO and undoped ZnO. Thus, the findings of this work support the developed system has a dual role as the photocatalyst, and antibacterial agent for efficient environmental remediation.

Green Route Synthesis and Characterization Techniques of Silver Nanoparticles and Their Biological Adeptness

The development of the most reliable and green techniques for nanoparticle synthesis is an emerging step in the area of green nanotechnology. Many conventional approaches used for nanoparticle (NP) synthesis are expensive, deadly, and nonenvironmental. In this new era of nanotechnology, to overcome such concerns, natural sources which work as capping and reducing agents, including bacteria, fungi, biopolymers, and plants, are suitable candidates for synthesizing AgNPs. The surface morphology and applications of AgNPs are significantly pretentious to the experimental conditions by which they are synthesized. Available scattered information on the synthesis of AgNPs comprises the influence of altered constraints and characterization methods such as FTIR, UV-vis, DLS, SEM, TEM, XRD, EDX, etc. and their properties and applications. This review focuses on all the above-mentioned natural sources that have been used for AgNP synthesis recently. The green routes to synthesize AgNPs have established effective applications in various areas, including biosensors, magnetic resonance imaging (MRI), cancer treatment, surface-enhanced Raman spectroscopy (SERS), antimicrobial agents, drug delivery, gene therapy, DNA analysis, etc. The existing boundaries and prospects for metal nanoparticle synthesis by the green route are also discussed herein.

Multifunctional green synthesized Cu-Al layered double hydroxide (LDH) nanoparticles: anti-cancer and antibacterial activities

Doxorubicin (DOX) is a potent anti-cancer agent and there have been attempts in developing nanostructures for its delivery to tumor cells. The nanoparticles promote cytotoxicity of DOX against tumor cells and in turn, they reduce adverse impacts on normal cells. The safety profile of nanostructures is an important topic and recently, the green synthesis of nanoparticles has obtained much attention for the preparation of biocompatible carriers. In the present study, we prepared layered double hydroxide (LDH) nanostructures for doxorubicin (DOX) delivery. The Cu–Al LDH nanoparticles were synthesized by combining Cu(NO₃)₂·3H₂O and Al(NO₃)₃·9H₂O, and then, autoclave at 110. The green modification of LDH nanoparticles with Plantago ovata (PO) was performed and finally, DOX was loaded onto nanostructures. The FTIR, XRD, and FESEM were employed for the characterization of LDH nanoparticles, confirming their proper synthesis. The drug release study revealed the pH-sensitive release of DOX (highest release at pH 5.5) and prolonged DOX release due to PO modification. Furthermore, MTT assay revealed improved biocompatibility of Cu–Al LDH nanostructures upon PO modification and showed controlled and low cytotoxicity towards a wide range of cell lines. The CLSM demonstrated cellular uptake of nanoparticles, both in the HEK-293 and MCF-7 cell lines; however, the results were showed promising cellular internalizations to the HEK-293 rather than MCF-7 cells. The in vivo experiment highlighted the normal histopathological structure of kidneys and no side effects of nanoparticles, further confirming their safety profile and potential as promising nano-scale delivery systems. Finally, antibacterial test revealed toxicity of PO-modified Cu–Al LDH nanoparticles against Gram-positive and -negative bacteria.

Silver nanostructures prepared via novel green approach as an effective platform for biological and environmental applications

Silver nanoparticles play a significant role in biomedical sciences due to their unique properties allowing for their use as an effective sensing and remediation platform Herein, the green synthesis of silver nanostructures (Ag NSs), prepared via aqueous extract of waste Brassica oleracea leaves in the presence of silver nitrate solution (10-4 M), is reported. The Ag NSs are fully characterized and their efficacy with respect to 4-nitrophenol reduction, glucose sensing, and microbes is determined. Visually, the color of silver nitrate containing solution altered from colorless to yellowish, then reddish grey, confirming the formation of Ag NSs. HRTEM and SEAD studies revealed the Ag NSs to have different morphologies (triangular, rod-shaped, hexagonal, etc., within a size range of 20-40 nm) with face-centered cubic (fcc) crystal structure. The Ag NSs possess high efficacy for nitrophenol reduction (<11 min and degradation efficiency of 98.2%), glucose sensing (LOD: 5.83 µM), and antimicrobial activity (E. coli and B. subtilis with clearance zones of 18.3 and 14 mm, respectively). Thus, the current study alludes towards the development of a cost-effective, sustainable, and efficient three-in-one platform for biomedical and environmental applications.

A Review on Green Synthesis of TiO2 NPs: Synthesis and Applications in Photocatalysis and Antimicrobial

Nanotechnology is a fast-expanding area with a wide range of applications in science, engineering, health, pharmacy, and other fields. Nanoparticles (NPs) are frequently prepared via a variety of physical and chemical processes. Simpler, sustainable, and cost-effective green synthesis technologies have recently been developed. The synthesis of titanium dioxide nanoparticles (TiO₂ NPs) in a green/sustainable manner has gotten a lot of interest in the previous quarter. Bioactive components present in organisms such as plants and bacteria facilitate the bio-reduction and capping processes. The biogenic synthesis of TiO₂ NPs, as well as the different synthesis methods and mechanistic perspectives, are discussed in this review. A range of natural reducing agents including proteins, enzymes, phytochemicals, and others, are involved in the synthesis of TiO₂ NPs. The physics of antibacterial and photocatalysis applications were also thoroughly discussed. Finally, we provide an overview of current research and future concerns in biologically mediated TiO₂ nanostructures-based feasible platforms for industrial applications.

Recent Advances in Green Synthesis of Ag NPs for Extenuating Antimicrobial Resistance

Combating antimicrobial resistance (AMR) is an on-going global grand challenge, as recognized by several UN Sustainable Development Goals. Silver nanoparticles (Ag NPs) are well-known for their efficacy against antimicrobial resistance, and a plethora of green synthesis methodologies now exist in the literature. Herein, this review evaluates recent advances in biological approaches for Ag NPs, and their antimicrobial potential of Ag NPs with mechanisms of action are explored deeply. Moreover, short and long-term potential toxic effects of Ag NPs on animals, the environment, and human health are briefly discussed. Finally, we also provide a summary of the current state of the research and future challenges on a biologically mediated Ag-nanostructures-based effective platform for alleviating AMR.

Spectral and structure characterization of Ferula assafoetida fabricated silver nanoparticles and evaluation of its cytotoxic, and photocatalytic competence

This study aims to develop an eco-friendly method for rapidly synthesizing silver nanoparticles (AgNPs) using Asafoetida ethanol extracts and to validate AgNPs synthesis using UV-vis spectroscopy (absorption spectrum), FTIR (functional groups), XRD (crystallinity), FE-SEM (size of the particles) and SEM-EDAX (Purity). Furthermore, to evaluate the anti-proliferative effect of Ag NPs against grown cultured L6 cell lines, studies have shown that AgNPs biosynthesis inhibits cancer cell growth compared to control cell lines. UV-vis absorption verified the existence of Ag NPs, and the spectrum was observed at 480 nm. Functional groups are present in the synthesized Ag NPs were shifted on 528.48 cm^-1 confirmed using an FT-IR spectrum. Consequently, anti-cancer efficacy observed the IC₅₀ value of As Ag NPs against L6 cells was 1.0 μg/mL for 48 h. Finally, using a halogen lamp, studies explored the photocatalytic degradation of AgNPs against the methylene blue radioactive dye and achieved a 96 percent degradation rate in 90 min. Asafoetida mediated silver nanoparticles show grater photodegradation for methylene blue dye, which is present in textile industries, when exposed to solar light, and it has a wide range of potential applications in wastewater treatment. As a whole, biosynthesized silver nanoparticles showed excellent cytotoxic, antioxidant, and photocatalytic dye degradation effects.

Ligustrum lucidum Leaf Extract-Assisted Green Synthesis of Silver Nanoparticles and Nano-Adsorbents Having Potential in Ultrasound-Assisted Adsorptive Removal of Methylene Blue Dye from Wastewater and Antimicrobial Activity

Present study was conducted to investigate the adsorption and ultrasound-assisted adsorption potential of silver nanoparticles (AgNPs) and silver nanoparticles loaded on chitosan (AgCS composite) as nano-adsorbents for methylene blue (MB) removal. AgNPs were synthesized using leaf extract of Ligustrum lucidum, which were incorporated on the chitosan’s surface for modification. UV−Vis Spectroscopy, FTIR, XRD, SEM, and EDX techniques were used to confirm the synthesis and characterization of nanomaterials. Batch adsorption and sono-adsorption experiments for the removal of MB were executed under optimal conditions; for fitting the experimental equilibrium data, Langmuir and Freundlich’s isotherm models were adopted. In addition, the antimicrobial potential of the AgNPs and AgCS were examined against selected bacterial and fungal strains. UV−Vis spectroscopy confirmed AgNPs synthesis from the leaf extract of L. lucidum used as a reducer, which was spherical as exposed in the SEM analysis. The FTIR spectrum illustrated phytochemicals in the leaf extract of L. lucidum functioning as stabilizing agents around AgNPs and AgCS. Whereas, corresponding crystalline peaks of nanomaterial, including a signal peak at 3 keV indicating the presence of silver, were confirmed by XRD and EDX. The Langmuir model was chosen as an efficient model for adsorption and sono-adsorption, which exposed that under optimum conditions (pH = 6, dye initial concentration = 5 mg L−1, adsorbents dosage = 0.005 g, time = 120 min, US power 80 W), MB removal efficiency of AgNPs was >70%, using ultrasound-assisted adsorption compared to the non-sonicated adsorption. Furthermore, AgNPs exhibited promising antibacterial potential against Staphylococcus aureus with the maximum zone of inhibition (14.67 ± 0.47 mm). It was concluded that the green synthesis approach for the large-scale production of metallic nanoparticles is quite effective and can be recommended for efficient and cost-effective way to eradicate dyes, particularly from textile wastewater.

Ecofriendly Synthesis of Silver Nanoparticles Using Ananas comosus Fruit Peels: Anticancer and Antimicrobial Activities

Metallic nanoparticles are valuable materials and have a range of uses. Nanoparticles synthesized from plant wastes by environment-friendly methods have attracted the attention of researchers in recent years. Also, the advantages of biological resources and synthesis methods are attracting attention. In this study, silver nanoparticles were synthesized from Ananas comosus fruit peels using ecofriendly method steps. The characterization of the particles obtained was determined by using a UV-visible spectrophotometer (UV-Vis.), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction diffractometer (XRD), Fourier scanning electron microscope (FESEM), and transmission electron microscopy (TEM). The nanoparticles showed maximum absorbance at 463 nm, measuring 11.61 in crystal nanosize, and presented spherical in appearance. An antimicrobial activity test was determined with the minimum inhibition concentration (MIC) method. The nanoparticles showed promising inhibitory activity on the Gram-positive and Gram-negative pathogen microorganisms (Escherichia coli ATCC25922, Staphylococcus aureus ATCC29213, Bacillus subtilis ATCC11774, Pseudomonas aeruginosa ATCC27833 bacteria, and Candida albicans yeast) at low concentrations. The cytotoxic and growth inhibitory effects of silver nanoparticles on different cancer cell lines were examined via the MTT assay.

Phyto-Extract-Mediated Synthesis of Silver Nanoparticles Using Aqueous Extract of Sanvitalia procumbens, and Characterization, Optimization and Photocatalytic Degradation of Azo Dyes Orange G and Direct Blue-15

Green synthesis of silver nanoparticles (AgNPs) employing an aqueous plant extract has emerged as a viable eco-friendly method. The aim of the study was to synthesize AgNPs by using plant extract of Sanvitalia procumbens (creeping zinnia) in which the phytochemicals present in plant extract act as a stabilizing and reducing agent. For the stability of the synthesized AgNPs, different parameters like AgNO3 concentration, volume ratios of AgNO3, temperature, pH, and contact time were studied. Further, AgNPs were characterized by UV-visible spectroscopy, FT-IR (Fourier Transform Infrared Spectroscopy), XRD (X-ray Diffraction), SEM (Scanning Electron Microscopy), and EDX (Energy Dispersive X-ray Spectrometer) analysis. FT-IR analysis showed that the plant extract contained essential functional groups like O-H stretching of carboxylic acid, N-H stretching of secondary amides, and C-N stretching of aromatic amines, and C-O indicates the vibration of alcohol, ester, and carboxylic acid that facilitated in the green synthesis of AgNPs. The crystalline nature of synthesized AgNPs was confirmed by XRD, while the elemental composition of AgNPs was detected by energy dispersive X-ray analysis (EDX). SEM studies showed the mean particle diameter of silver nanoparticles. The synthesized AgNPs were used for photocatalytic degradation of Orange G and Direct blue-15 (OG and DB-15), which were analyzed by UV-visible spectroscopy. Maximum degradation percentage of OG and DB-15 azo dyes was observed, without any significant silver leaching, thereby signifying notable photocatalytic properties of AgNPs.

The Recent Progress on Silver Nanoparticles: Synthesis and Electronic Applications

Nanoscience enables researchers to develop new and cost-effective nanomaterials for energy, healthcare, and medical applications. Silver nanoparticles (Ag NPs) are currently increasingly synthesized for their superior physicochemical and electronic properties. Good knowledge of these characteristics allows the development of applications in all sensitive and essential fields in the service of humans and the environment. This review aims to summarize the Ag NPs synthesis methods, properties, applications, and future challenges. Generally, Ag NPs can be synthesized using physical, chemical, and biological routes. Due to the great and increasing demand for metal and metal oxide nanoparticles, researchers have invented a new, environmentally friendly, inexpensive synthetic method that replaces other methods with many defects. Studies of Ag NPs have increased after clear and substantial support from governments to develop nanotechnology. Ag NPs are the most widely due to their various potent properties. Thus, this comprehensive review discusses the different synthesis procedures and electronic applications of Ag NPs.

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.

Recent progress in green and biopolymer based photocatalysts for the abatement of aquatic pollutants

Enormous research studies on the abatement of anthropogenic aquatic pollutants including organic dyes, pesticides, cosmetics, antibiotics and inorganic species by using varieties of semiconductor photocatalysts have been reported in recent decades. Besides, many of these photocatalysts suffer in real applications owing to their high production cost and low stability. In many cases, the photocatalysts themselves are being considered as secondary pollutants. To eliminate these drawbacks, the green synthesized photocatalysts and the use of biopolymers as photocatalyst supports are considered in recent years. In this context, recent developments in green synthesized metals, metal oxides, other metal compounds, and carbon based photocatalysts in water purification are critically reviewed. Furthermore, the pivotal role of biopolymers including chitin, chitosan, cellulose, natural gum, hydroxyapatite, alginate in photocatalytic removal of aquatic pollutants is comprehensively reviewed. The presence of functional groups, electron trapping ability, biocompatibility, natural occurrence, and low production cost are the major reasons for using biopolymers in photocatalysis. Finally, the summary and conclusion are presented along with existing challenges in this research area.

Reduction of 4-nitrophenol Mediated by Silver Nanoparticles Synthesized using Aqueous Leaf Extract of Peronema canescens

In this study, we developed an alternative of 4-nitrophenol reduction mediated by silver nanoparticles (AgNPs) which was synthesized using aqueous extract of the Peronema canescens leaf through an eco-friendly approach. The reducing 4-nitrophenol to 4-aminophenol mediated by AgNPS in the presence of sodium borohydride as a hydrogen source proceeded rapidly at room temperature without any additional treatments. The AgNPS synthesis was simple and was carried out under mild conditions. Ultraviolet–visible spectroscopy was performed to examine the properties of the obtained AgNPs, which displayed an absorption peak at 431 nm. A transmission electron microscopy analysis revealed that the AgNPs were spherical in shape and had an average particle size of 19 nm as determined by particle size analysis. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Hg(II) sensing, catalytic, antioxidant, antimicrobial, and anticancer potential of Garcinia mangostana and α-mangostin mediated silver nanoparticles

This study reports synthesis of Garcinia mangostana fruit pericarp (unwanted waste material) and α-mangostin mediated silver nanoparticles (AgNPs). These AgNPs were efficiently produced using 1:10 (extract and salt) ratio under stirring and heating, which was confirmed by surface plasmon resonance (SPR) band in UV-Visible spectroscopic analysis, and size of 73-91 nm determined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The synthesized AgNPs were used for Hg(II) detection in tap water, where the limits of detection and quantification were 2.6 μM and 8.9 μM, respectively. Furthermore, the subject AgNPs showed promising catalytic activity in the reduction of dyes and food colours including Congo red (CR), methylene blue (MB), malachite green (MG), methyl orange (MO), para-nitrophenol (PNP), rhodamine B (RdB), zarda yellow (ZY), deep green (DG), and bright red (BR). The synthesized AgNPs were also evaluated for their antioxidant, antimicrobial, and anticancer properties, where α-mangostin and its nanoparticles (Mang-AgNPs) exhibited promising IC₅₀ values of 14.1 and 13.5 μg/mL, respectively against DU-145 cell line validated by in silico molecular docking study. This study is the first report highlighting the application of AgNPs of G. mangostana fruit pericarp extracts, and α-mangostin in Hg(II) detection, dyes degradation, and anticancer potential against DU-145. Finding of this study suggested the suitability of AgNPs as promising solid biosensor in Hg(II) metal detection, dyes reduction, and target in anticancer drug development.

Phytochemical mediated synthesis of silver nanoparticles and their antibacterial activity

In this present work, we described a bio-reduction method for the generation of silver nanoparticles (AgNPs) using aqueous leaf extract of Micrargeria wightii (M. wightii), which is a gifted alternative to other physicochemical routes. The prepared AgNPs were characterized by UV–visible spectroscopy (UV–vis), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (X-RD), Transmission Electron Microscopy (TEM) with EDX and Dynamic light scattering (DLS). UV–visible spectrum showed a characteristic absorption peak at 440 nm of synthesized AgNPs. FT-IR analysis confirmed the existence of plant metabolites, which are responsible for the reduction of Ag (I) ions into Ag (0) NPs. X-RD pattern studies confirm the presence of the pure face-centered cubiccrystalline nature of Ag. Energy-dispersive X-ray (E-DX) spectrum showed the elemental composition of synthesized nanoparticles. Furthermore, TEM images confirm the formation of spherical shaped nano-silver particles with sizes ranging from 30 to 70 nm and supported by particle size analyzer, Dynamic Light Scattering (DLS). Thus, the present investigation provides an easy, eco-friendly and straightforward route for the synthesis of the antibacterial agent against Bacillus subtilis subtilis and Pseudomonas aeruginosa, with 15 and 13 mm zone of inhibition (ZOI) respectively.

Antibacterial and Antifungal Studies of Biosynthesized Silver Nanoparticles against Plant Parasitic Nematode Meloidogyne incognita, Plant Pathogens Ralstonia solanacearum and Fusarium oxysporum

The possibility of using silver nanoparticles (AgNPs) to enhance the plants growth, crop production, and control of plant diseases is currently being researched. One of the most effective approaches for the production of AgNPs is green synthesis. Herein, we report a green and phytogenic synthesis of AgNPs by using aqueous extract of strawberry waste (solid waste after fruit juice extraction) as a novel bioresource, which is a non-hazardous and inexpensive that can act as a reducing, capping, and stabilizing agent. Successful biosynthesis of AgNPs was monitored by UV-visible spectroscopy showing a surface plasmon resonance (SPR) peak at ~415 nm. The X-ray diffraction studies confirm the face-centered cubic crystalline AgNPs. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques confirm the rectangular shape with an average size of ~55 nm. The antibacterial and antifungal efficacy and inhibitory impact of the biosynthesized AgNPs were tested against nematode, Meloidogyne incognita, plant pathogenic bacterium, Ralstonia solanacearum and fungus, Fusarium oxysporum. These results confirm that biosynthesized AgNPs can significantly control these plant pathogens.

Synthesis of ZnO nanoparticles using peels of Passiflora foetida and study of its activity as an efficient catalyst for the degradation of hazardous organic dye

Creating a sustainable and effective approach to handling organic contaminants from industrial waste is an ongoing problem. In the present study, ZnO nanoparticles (ZnO NPs) were synthesized under a controlled ultrasound cavitation technique using the extract of Passiflora foetida fruit peels, which act as a reducing (i.e., reduction of metal salt) and stabilizing agent. The formation of monodispersed and hexagonal morphology (average size approximately 58 nm with BET surface area 30.83m2/g). The synthesized ZnO NPs were characterized by a various technique such as UV–visible spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared (FTIR), Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA) and Dynamic light scattering (DLS). Further, the XRD pattern confirmed the hexagonal wurtzite structure of synthesized ZnONPs. The ZnO NPs exhibit excellent degradation efficiency towards organic pollutant dyes, i.e., Methylene blue (MB) (93.25% removal) and Rhodamine B (91.06% removal) in 70 min, under natural sunlight with apparent rate constant 0.0337 min−1 (R2 = 0.9749) and 0.0347 min−1 (R2 = 0.9026) respectively.Zeta potential study shows the presence of a negative charge on the surface of ZnO NPs. The use of green synthesized ZnO NPs is a good choice for wastewater treatment, given their high reusability and photocatalytic efficiency, along with adaptability to green synthesis.

Catalytic Degradability of p-Nitrophenol Using Ecofriendly Silver Nanoparticles

In an effort to produce non-toxic and economically viable “green” protocols for waste water treatment, researchers are actively involved to develop versatile and effective silver nanoparticles (SNPs) as nano-catalyst from bio-based techniques. Since, p-nitrophenol (PNP) is one of the anthropogenic contaminants, considerable attention has been focused in catalytic degradability of PNP in wastewater treatment by curtailing serious effect on aquatic fauna. Ingestion of contaminants by aquatic organisms will not only affect the aquatic species but is also a potential threat to human health, especially if the toxic contaminants are involved in food chain. In this short report, we provided a comprehensive insight on few remarkable nanocatalysts especially based on SNPs and its biopolymer composites synthesized via ecofriendly “green” route. The beneficiality and catalytic performance of these silver nanocatalysts are concisely documented on standard model degradation reduction of PNP to p-aminophenol (PAP) in the presence of aqueous sodium borohydride. The catalytic degradation of PNP to PAP using SNPs follows pseudo first order kinetics involving six-electrons with lower activation energy. Furthermore, we provided a list of highly effective, recoverable, and economically viable SNPs, which demonstrated its potential as nanocatalysts by focusing its technical impact in the area of water remediation.