Green synthesis of silver nanoparticles using Piper longum catkin extract irradiated by sunlight: antibacterial and catalytic activity

Biogenic synthesis of silver nanoparticles using Rubus fruticosus extract and their antibacterial efficacy against Erwinia caratovora and Ralstonia solanacearum phytopathogens

In the current research, we produced green, cost-effective, eco-friendly silver nanoparticles using a single-step approach. Plants are considered highly desirable systems for nanoparticle synthesis because they possess a variety of secondary metabolites with significant reduction potential. In the current research, the dried leaf extract of Rubus fruticosus was utilized as a capping and reducing agent for the fabrication of silver nanoparticles, to prepare reliable biogenic silver nanoparticles and subsequently to investigate their potential against some common phytopathogens. The prepared silver nanoparticles were exploited to quantify the total flavonoid content (TFC), total phenolic content (TPC) and DPPH-based antioxidant activity. Different concentrations of aqueous extracts of plant leaves and silver nitrate (AgNO3) were reacted, and the color change of the reactant mixture confirmed the formation of Rubus fruticosus leaf-mediated silver nanoparticles (RFL-AgNPs). A series of characterization techniques such as UV-vis spectroscopy, transmission electron microscopy, energy dispersive X-ray analysis and X-ray diffraction revealed the successful synthesis of silver nanoparticles. The surface plasmon resonance peak appeared at 449 nm. XRD analysis demonstrated the crystalline nature, EDX confirmed the purity, and TEM demonstrated that the nanoparticles are mostly spherical in form. Furthermore, the biosynthesized nanoparticles were screened for in vitro antibacterial activity, antioxidant activity, and total phenolic and flavonoid content. The nanoparticles were used in different concentrations alone and in combination with plant extracts to inhibit Erwinia caratovora and Ralstonia solanacearum. In high-throughput assays used to inhibit these plant pathogens, the nanoparticles were highly toxic against bacterial pathogens. This study can be exploited for planta assays against phytopathogens utilizing the same formulations for nanoparticle synthesis and to develop potent antibacterial agents to combat plant diseases.

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.

Diffused sunlight assisted green synthesis of silver nanoparticles using Cotoneaster nummularia polar extract for antimicrobial and wound healing applications

The current study reports the synthesis of silver nanoparticles (Ag NPs) using a polar extract of Cotoneaster nummularia leaves. Various analytical techniques, like UV-Vis spectrophotometry, FT-IR spectroscopy, XRD, SEM, and EDX were employed for characterisation. These techniques confirmed the stability of Ag NPs in solution and endorsed the interaction between different groups and Ag, crystal phase, surface morphology, and size of Ag NPs. UV-Vis spectrophotometer displayed SPR absorption bands ranging from 380 to 470 nm, characteristic of Ag NPs, within 1.0 h exposure to sunlight. XRD and SEM discovered the face-centered cubic crystals of Ag NPs with a 122.8 ± 1.1 nm average diameter. The bands at 525 cm-1 in FT-IR spectrum supported the development of Ag NPs. The Ag NPs showed antimicrobial potential against three pathogenic bacterial strains and two fungal strains. The wound healing results, as studied by tissue re-development and wound closure in rabbits were comparable to standard Sufre tulle® dressing.

Antioxidant Activities of Photoinduced Phycogenic Silver Nanoparticles and Their Potential Applications

While various methods exist for synthesizing silver nanoparticles (AgNPs), green synthesis has emerged as a promising approach due to its affordability, sustainability, and suitability for biomedical purposes. However, green synthesis is time-consuming, necessitating the development of efficient and cost-effective techniques to minimize reaction time. Consequently, researchers have turned their attention to photo-driven processes. In this study, we present the photoinduced bioreduction of silver nitrate (AgNO₃) to AgNPs using an aqueous extract of Ulva lactuca, an edible green seaweed. The phytochemicals found in the seaweed functioned as both reducing and capping agents, while light served as a catalyst for biosynthesis. We explored the effects of different light intensities and wavelengths, the initial pH of the reaction mixture, and the exposure time on the biosynthesis of AgNPs. Confirmation of AgNP formation was achieved through the observation of a surface plasmon resonance band at 428 nm using an ultraviolet-visible (UV-vis) spectrophotometer. Fourier transform infrared spectroscopy (FTIR) revealed the presence of algae-derived phytochemicals bound to the outer surface of the synthesized AgNPs. Additionally, high-resolution transmission electron microscopy (HRTEM) and atomic force microscopy (AFM) images demonstrated that the NPs possessed a nearly spherical shape, ranging in size from 5 nm to 40 nm. The crystalline nature of the NPs was confirmed by selected area electron diffraction (SAED) and X-ray diffraction (XRD), with Bragg's diffraction pattern revealing peaks at 2θ = 38°, 44°, 64°, and 77°, corresponding to the planes of silver 111, 200, 220, and 311 in the face-centered cubic crystal lattice of metallic silver. Energy-dispersive X-ray spectroscopy (EDX) results exhibited a prominent peak at 3 keV, indicating an Ag elemental configuration. The highly negative zeta potential values provided further confirmation of the stability of AgNPs. Moreover, the reduction kinetics observed via UV-vis spectrophotometry demonstrated superior photocatalytic activity in the degradation of hazardous pollutant dyes, such as rhodamine B, methylene orange, Congo red, acridine orange, and Coomassie brilliant blue G-250. Consequently, our biosynthesized AgNPs hold great potential for various biomedical redox reaction applications.

Identifying the Anti-MERS-CoV and Anti-HcoV-229E Potential Drugs from the Ginkgo biloba Leaves Extract and Its Eco-Friendly Synthesis of Silver Nanoparticles

The present study aimed to estimate the antiviral activities of Ginkgo biloba (GB) leaves extract and eco-friendly free silver nanoparticles (Ag NPs) against the MERS-CoV (Middle East respiratory syndrome-coronavirus) and HCoV-229E (human coronavirus 229E), as well as isolation and identification of phytochemicals from GB. Different solvents and high-performance liquid chromatography (HPLC) were used to extract and identify flavonoids and phenolic compounds from GB leaves. The green, silver nanoparticle synthesis was synthesized from GB leaves aqueous extract and investigated for their possible effects as anti-coronaviruses MERS-CoV and HCoV-229E using MTT assay protocol. To verify the synthesis of Ag NPs, several techniques were employed, including X-ray diffraction (XRD), scan, transmission electron microscopy, FT-IR, and UV-visible spectroscopy. The highest contents of flavonoids and phenolic compounds were recorded for acetone, methanol, and ethanol as mixtures with water, in addition to pure water. HPLC flavonoids were detected as apegenin, luteolin, myricetin, and catechin, while HPLC phenolic compounds were pyrogallol, caffeic acid, gallic acid, and ellagic acid. In addition, our results revealed that Ag NPs were produced through the shift from yellow to dark brown. TEM examination of Ag NPs revealed spherical nanoparticles with mean sizes ranging from 5.46 to 19.40 nm and an average particle diameter of 11.81 nm. A UV-visible spectrophotometric investigation revealed an absorption peak at λ max of 441.56 nm. MTT protocol signified the use of GB leaves extract as an anti-coronavirus to be best from Ag NPs because GB extract had moderate anti-MERS-CoV with SI = 8.94, while had promising anti-HCov-229E, with an SI of 21.71. On the other hand, Ag NPs had a mild anti-MERS-CoV with SI = 4.23, and a moderate anti-HCoV-229E, with an SI of 7.51.

Green synthesis of silver nanoparticles using Eupatorium adenophorum leaf extract: characterizations, antioxidant, antibacterial and photocatalytic activities

The green synthesis of metallic nanoparticles has tremendous impacts in various fields as found in recent years due to their low cost, easy and environmentally friendly synthesis. In this article, we report a simple and eco-friendly method for the synthesis of silver nanoparticles (AgNPs) using an aqueous Eupatorium adenophorum (E. adenophorum) leaf extract as a bioreductant. Interestingly, Fourier transform infrared (FTIR) spectroscopy analysis established that the E. adenophorum extract not only served as a bioreductant but also acted as a capping agent to stabilize the nanoparticles by functionalizing the surfaces. Various characterization techniques were adopted, such as X-ray powder diffraction (XRD), FTIR, ultraviolet-visible absorption (UV-Vis) spectroscopy, dynamic light scattering, scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDX) to analyze the biosynthesized AgNPs. Biosynthesized nanoparticles were also explored for antioxidant, antibacterial and photocatalytic activities. The AgNPs showed improved free radical scavenging activity (IC₅₀ 48.96 ± 0.84 µg/mL) and bacterial inhibitory effects against both gram-positive (Staphylococcus aureus; 64.5 µg/mL) and gram-negative (Escherichia coli; 82.5 µg/mL) bacteria. Photocatalytic investigation showed AgNPs were effective at degrading rhodamine dye (78.69% in 90 min) when exposed to sunlight. These findings collectively suggest that E. adenophorum AgNPs were successfully prepared without the involvement of any hazardous chemical and it may be an effective antibacterial, antioxidant and promising agent for the removal of hazardous dye from waste water produced by industrial dyeing processes.

Green synthesis of silver nanoparticles using Coffea canephora fruit skin extract and its application for mercury detection in face cream samples

Mercury is one of the most toxic heavy metals causing harmful effects on the human body; meanwhile, mercury is found in some face cream products to give a whitening effect. The upper limit concentration of mercury in skin-lightening products defined by the Food and Drug Administration (FDA) is under one mg/L as Hg²⁺. A new green analytical spectrophotometric method for mercury analysis has been developed by employing a biological reagent from fruit skin extract of robusta coffee (Coffea canephora) as a bioreductor for silver ions as well as a stabilizer for the AgNPs product. The detection principle of this method is based on the decrease of the color intensity of silver nanoparticles (AgNPs) after the addition of Hg²⁺ ions due to the re-oxidization of the AgNPs by Hg²⁺ ions to colorless Ag⁺ ions. To achieve the most significant sensitivity, linearity of measurement, and validity, the method was optimized toward the volume of AgNPs and reaction time. In this research, the synthesized AgNPs were also characterized by UV-Vis Spectrometry as well as a particle size analyzer (PSA) to determine the size of nanoparticles. The result showed that the optimum conditions were attained at 4 mL AgNPs solution and 3-min reaction resulting in a linear measurement of Hg²⁺ in the range of 0-15 mg/L with LOD and LOQ of 0.039 and 0.130 mg/L, respectively. This method is quite selective and has been validated by applying it to real face cream samples with satisfactory results supported by average recoveries of close to 100%.

Phytotoxicity and Antimicrobial Activity of Green Synthesized Silver Nanoparticles Using Nigella sativa Seeds on Wheat Seedlings

Recently, the green synthesis of nanomaterials has grown in popularity and has become one of the most used approaches. Plant extracts are safe for the environment and could be cost-effective for nanoparticle preparation. Silver nanoparticles (AgNPs) have been synthesized using aqueous extracts of Nigella sativa (N. sativa) seeds. The formation of AgNPs was confirmed by using an X-ray diffractometer, a UV-visible spectrometer, and a transmission electron microscope. The phytotoxicity and genotoxicity of different AgNP concentrations (12.5, 25, 50, 75, and 100 μg·L−1) were evaluated by wheat (Triticum aestivum L.) seed germination. The results showed that AgNPs did not significantly affect germination, while root and coleoptile lengths decreased considerably. On the contrary, the biomass of seedlings markedly increased in response to AgNP treatments. Moreover, genotoxicity was detected, especially at high concentrations of AgNPs. DNA, RNA, and total soluble proteins of wheat seedlings significantly decreased. In addition, antimicrobial activities of biosynthesized AgNPs were detected.

Piper longum L.: A comprehensive review on traditional uses, phytochemistry, pharmacology, and health-promoting activities

Piper longum (family Piperaceae), commonly known as "long-pepper" or "Pippali" grows as a perennial shrub or as an herbaceous vine. It is native to the Indo-Malaya region and widely distributed in the tropical and subtropical world including the Indian subcontinent, Sri Lanka, Middle-East, and America. The fruits are mostly used as culinary spice and preservatives and are also a potent remedy in various traditional medicinal systems against bronchitis, cough, cold, snakebite, and scorpion-sting and are also used as a contraceptive. Various bioactive-phytochemicals including alkaloids, flavonoids, esters, and steroids were identified from the plant extracts and essential oils from the roots and fruits were reported as antimicrobial, antiparasitic, anthelminthic, mosquito-larvicidal, antiinflammatory, analgesic, antioxidant, anticancer, neuro-pharmacological, antihyperglycaemic, hepato-protective, antihyperlipidaemic, antiangiogenic, immunomodulatory, antiarthritic, antiulcer, antiasthmatic, cardioprotective, and anti-snake-venom agents. Many of its pharmacological properties were attributed to its antioxidative and antiinflammatory effects and its ability to modulate a number of signalling pathways and enzymes. This review comprehensively encompasses information on habit, distribution, ethnobotany, phytochemistry, and pharmacology of P. longum in relation to its medicinal importance and health benefits to validate the traditional claims supported by specific scientific experiments. In addition, it also discusses the safety and toxicity studies, application of green synthesis and nanotechnology as well as clinical trials performed with the plant also elucidating research gaps and future perspectives of its multifaceted uses.

Sunlight-Mediated Green Synthesis of Silver Nanoparticles Using the Berries of Ribes rubrum (Red Currants): Characterisation and Evaluation of Their Antifungal and Antibacterial Activities

Plants are a treasure trove of several important phytochemicals that are endowed with therapeutic and medicinal properties. Ribes rubrum L. (red currants) are seasonal berries that are widely consumed for their nutritional value and are known for their health benefits. Red currants are a rich source of secondary metabolites such as polyphenols, tocopherols, phenolic acids, ascorbic acid, and flavonoids. In this study, sunlight-mediated synthesis of silver nanoparticles (AgNPs) was successfully accomplished within 9 min after adding the silver nitrate solution to the aqueous extract of red currant. The synthesised AgNPs were characterised with UV–Vis, transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier transform infrared spectrum (FTIR), and energy-dispersive X-ray spectrum (EDX). The efficacy of aqueous extracts of red currants and AgNPs in controlling the growth of some pathogenic fungi and bacteria was also investigated. The UV–visible (UV–Vis) spectrum displayed an absorption peak at 435 nm, which corresponded to the surface plasmon band. The strong silver signal on the EDX spectrum at 3 keV, authenticated the formation of AgNPs. The several peaks on the FTIR spectrum of the aqueous extract of red currant and the nanoparticles indicated the presence of some important functional groups such as amines, carbonyl compounds, and phenols that are vital in facilitating the process of capping and bioreduction, besides conferring stability to nanoparticles. The TEM microphotographs showed that the nanoparticles were well dispersed, roughly spherical, and the size of the nanoparticles ranged from 8 to 59 nm. The red currant silver nanoparticles were highly potent in inhibiting the growth and proliferation of some fungal and bacterial test isolates, especially Alternaria alternata, Colletotrichum musae, and Trichoderma harzianum. Based on the robust antifungal and antibacterial activity demonstrated in this study, red currant nanoparticles can be investigated as potential replacements for synthetic fungicides and antibiotics.

Green Synthesis of Metal and Metal Oxide Nanoparticles: Principles of Green Chemistry and Raw Materials

Increased request for metal and metal oxide nanoparticles nanoparticles has led to their large-scale production using high-energy methods with various toxic solvents. This cause environmental contamination, thus eco-friendly “green” synthesis methods has become necessary. An alternative way to synthesize metal nanoparticles includes using bioresources, such as plants and plant products, bacteria, fungi, yeast, algae, etc. “Green” synthesis has low toxicity, is safe for human health and environment compared to other methods, meaning it is the best approach for obtaining metal and metal oxide nanoparticles. This review reveals 12 principles of “green” chemistry and examples of biological components suitable for “green” synthesis, as well as modern scientific research of eco-friendly synthesis methods of magnetic and metal nanoparticles. Particularly, using extracts of green tea, fruits, roots, leaves, etc., to obtain Fe3O4 NPs. The various precursors as egg white (albumen), leaf and fruit extracts, etc., can be used for the „green” synthesis of spinel magnetic NPs. “Green” nanoparticles are being widely used as antimicrobials, photocatalysts and adsorbents. “Green” magnetic nanoparticles demonstrate low toxicity and high biocompatibility, which allows for their biomedical application, especially for targeted drug delivery, contrast imaging and magnetic hyperthermia applications. The synthesis of silver, gold, platinum and palladium nanoparticles using extracts from fungi, red algae, fruits, etc., has been described.

State-of-art of silver and gold nanoparticles synthesis routes, characterization and applications: a review

To date, the noble metal-based nanoparticles have been used in every field of life. The Au and Ag nanoparticles (NPs) have been fabricated employing different techniques to tune the properties. In this study, the methodologies developed and adopted for the fabrication of Au and Ag have been discussed, which include physical, chemical and biological routes. The Au and Ag characteristics (morphology, size, shape) along with advantages and disadvantages are discussed. The Au and Ag NPs catalytic and biomedical applications are discussed. For the Ag and Au NPs characterization, SEM (scanning electron microscope), TEM (transmission electron microscope), FTIR (Fourier transform infra-red spectroscopy), XRD (X-rays diffraction) and DLS (dynamic light scattering) techniques are employed. The properties of Au and Ag NPs found dependent to synthesis approach, i.e., the size, shape and morphologies, which showed a promising Catalytic, drug delivery and antimicrobial agent applications. The review is a comprehensive study for the comparison of Au and Ag NPs synthesis, properties and applications in different fields.

Prospective of biosynthesized L.satiVum oil/PEG/Ag-MgO bionanocomposite film for its antibacterial and anticancer potential

A substantial interest has been manifested in utilizing oil/metal oxide hybrid bionanocomposite, especially organic/ inorganic to design different biomedical applications. The present study reports the synthesis, characterization, antibacterial and anticancer properties of biogenic silver nanoparticles (AgNPs) and L.satiVum oil/PEG/Ag-MgO bionanocomposite. The fabricated AgNPs and L.sativum oil/PEG/Ag-MgO bionanocomposite were characterized by employing different spectroscopic (UV, FTIR, XRD) and microscopic (TEM, SEM) techniques. The particle size analysis showed that the mean size of 16.32 nm for AgNPS and 13.45 nm L.satiVum oil/PEG/Ag-MgO, indicating the excellent dispersion of Ag-MgO nanoparticles in the PEG- L.satiVum oil matrix. The antimicrobial activity of AgNPs and polymeric bionanocomposite was investigated against two pathogenic bacteria. The highest antibacterial effect was observed for bionanocomposite towards Gram-positive Staphylococcus aureus (27 mm) and Gram-negative Escherichia coli (25 mm) at 40 µg/well. The bionanocomposite completely vanished the bacterial growth (100%) at 80 µgmL-1 concentrations. Moreover, the AgNPs and polymeric bionanocomposite was evaluated for anticancer activity against human cervical cancer cells (HeLa cells) at different doses (50, 250, 500, and 1000 µgmL-1). The results showed polymeric bionanocomposite was stronger in inducing the HeLa cancer cell death than AgNPs. Overall, the fabricated L.satiVum oil/PEG/Ag-MgO bionanocomposite serve as a potential antimicrobial and anticancer agent and could be used in the development of novel drugs and health care products in near future.

Photochemical Synthesis of Gold and Silver Nanoparticles-A Review

Nanomaterials have supported important technological advances due to their unique properties and their applicability in various fields, such as biomedicine, catalysis, environment, energy, and electronics. This has triggered a tremendous increase in their demand. In turn, materials scientists have sought facile methods to produce nanomaterials of desired features, i.e., morphology, composition, colloidal stability, and surface chemistry, as these determine the targeted application. The advent of photoprocesses has enabled the easy, fast, scalable, and cost- and energy-effective production of metallic nanoparticles of controlled properties without the use of harmful reagents or sophisticated equipment. Herein, we overview the synthesis of gold and silver nanoparticles via photochemical routes. We extensively discuss the effect of varying the experimental parameters, such as the pH, exposure time, and source of irradiation, the use or not of reductants and surfactants, reagents' nature and concentration, on the outcomes of these noble nanoparticles, namely, their size, shape, and colloidal stability. The hypothetical mechanisms that govern these green processes are discussed whenever available. Finally, we mention their applications and insights for future developments.

Green synthesis of Fe nanoparticles by using Mangifera indica extract and its application in photo-catalytic degradation of dyes

An exceedingly facile green approach that produces a reliable adsorbent based on a transition metal such as Iron (Fe) using Mangifera indica leaf extract at room temperature is described. A single pot method was used for synthesis with no capping agents, surfactants or other templates. The main intention of this study is to synthesize iron nanoparticles from leaf extract (Mangifera indica) and examine its degradation potential for photo-catalytic removal of dyes (Congo red and brilliant green) from wastewater. Characterization of synthesized nanoparticles was executed by pH_pzc, scanning electron microscopy and Fourier transform infrared spectroscopy studies and results confirm the presence of iron nano-sheets with biomolecules. All photo-catalytic experimental results were assessed by sum of squared estimate of errors and simple linear regression R² with dye concentration, pH, contact time and dose rate as dependent and independent variables. Adsorption experimental data was verified by kinetics and isothermal models. Results showed that Langmuir and pseudo second order models give best fitness towards the photo-catalytic adsorption procedure. Thermodynamics revealed that adsorption mechanism is endothermic, described by the values of changes in Gibbs free energy, enthalpy and entropy, and is chemisorption in nature, with spontaneous processes. Overall photo-catalytic adsorption execution with synthesized iron nanoparticles and simple biomass of Mangifera indica gives satisfactory results for treating dye wastewater.

Green synthesis of silver nanoparticles by Rivina humilis leaf extract to tackle growth of Brucella species and other perilous pathogens

Novel approaches are obligatory to treat chronic intracellular bacterial infectious diseases like Brucellosis specifically, are very complicated to deal with. The aim of the study to take upon nanotechnology approach to exploit the efficacy of the synthesized nanoparticles, to overcome barriers for treatment of Brucella species and other pathogens. Present study used Rivina humilis extract as reductant of silver ions for synthesis of silver nanoparticles for the first time. Rh-AgNP's was characterized by UV-visible spectroscopy, DLS, FT-IR, SEM, EDS, TEM and XRD. Radical scavenging, antibrucellosis, bactericidal activity was evaluated. Clinical application was assessed by Rate of haemolysis, fibrinolytic and Hemagglutination activity. UV-visible spectrum of synthesized Rh-AgNP's showed maximum peak at 440 nm indicating the formation of nanoparticles. TEM showed that the average particle size of nanoparticles 51 nm with spherical shape, DLS depicted monodisperse state in water; EDS confirmed the presence of silver metal. Rh-AgNP's exhibited potential antibrucellosis activity against B. abortus, B. melitensis and B. suis effective inhibition at 800 μg/mL. The bio-compatibility of Rh-AgNP's was established by rate of haemolysis, hemagglutination and fibrinolytic activity. For the first time it has been proved that Rh-AgNP's have efficacy as antimicrobial agent with potential application in the biological domain.

Green Synthesis of Gold and Silver Nanoparticles by Using Amorphophallus paeoniifolius Tuber Extract and Evaluation of Their Antibacterial Activity

In this report, we discussed rapid, facile one-pot green synthesis of gold and silver nanoparticles (AuNPs and AgNPs) by using tuber extract of Amorphophallus paeoniifolius, and evaluated their antibacterial activity. AuNPs and AgNPs were synthesized by mixing their respective precursors (AgNO₃ and HAuCl₄) with tuber extract of Amorphophallus paeoniifolius as the bio-reducing agent. Characterization of AuNPs and AgNPs were confirmed by applying UV-vis spectroscopy, field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), and energy dispersive X-ray spectroscopy (EDS). From UV-vis characterization, surface plasmon resonance spectra were found at 530 nm for AuNPs and 446 nm for AgNPs. XRD data confirmed that both synthesized nanoparticles were face-centered cubic in crystalline nature, and the average crystallite sizes for the assign peaks were 13.3 nm for AuNPs and 22.48 nm for AgNPs. FTIR data evaluated the characteristic peaks of different phytochemical components of tuber extract, which acted as the reducing agent, and possibly as stabilizing agents. The antibacterial activity of synthesized AuNPs and AgNPs were examined in Muller Hinton agar, against two Gram-positive and four Gram-negative bacteria through the disc diffusion method. AuNPs did not show any inhibitory effect, while AgNPs showed good inhibitory effect against both Gram-positive and Gram-negative bacteria.

Synthesis, optimization and characterization of silver nanoparticles using the catkin extract of Piper longum for bactericidal effect against food-borne pathogens via conventional and mathematical approaches

Inspired with an increasing environmental awareness, we performed an eco-friendly amenable process for the synthesis of silver nanoparticles (AgNPs) using the catkins of Piper longum as an alternative approach with the existing methods of using plant extracts. The fabrication of nanoparticles occurred within 10 min. This was initially observed by colour change of the solution. UV-visible spectroscopic studies (UV-Vis) were performed for further confirmation. The analysis elucidated that the surface plasmon resonance (SPR) was specifically corresponding to AgNPs. Fourier transform infrared spectrophotometry (FTIR) studies indicated that polyphenols could possibly be the encapsulating agents. The size and shape of the nanoparticles was analysed using Transmission electron microscopy (TEM). The nanoparticles were predominant spheres ranging between 10 and 42 nm at two different scales. The formation of elemental silver was confirmed further by X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction (XRD). GC-MS analysis was used to identify the possible encapsulates on the nanoparticles. The antibacterial effect of the biosynthesized AgNPs was tested against two gram-positive (Bacillus cereus and Staphylococcus aureus), and five gram-negative (Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae, Pseudomonas aeruginosa and Salmonella typhi) bacteria. Outcomes of the study suggest that these pathogens were susceptible to the AgNPs. This is the first ever international report on correlating the antibacterial effect of silver nanoparticles using mathematical modelling with a conventional antimicrobial assay. The results indicate that nanoparticles of silver synthesized using catkin extract of P. longum can be exploited towards the development of potential antibacterial agents.

Sunlight-Driven Synthesis of Silver Nanoparticles Using Pomelo Peel Extract and Antibacterial Testing

A green approach, including using phytochemicals in pomelo peel extract (PPE) and direct sunlight, was used to synthesize silver nanoparticles (AgNPs). PPE was prepared by treating pomelo peel with a citric acid solution at 85°C for 2 h. PPE was then mixed with AgNO3 and exposed to sunlight to induce the formation of AgNPs. Time-dependent UV-vis spectra of the reaction mixture demonstrated that AgNPs are formed under sunlight irradiation faster than underheating at 90°C. Characterization techniques, including X-ray diffraction, transmission electron microscopy, and scanning electron microscopy, confirmed the formation of AgNPs with sizes of 20–30 nm. AgNPs synthesized in PPE were more stable toward electrolyte-induced aggregation than those synthesized using the conventional NaBH4/citrate method. The AgNPs synthesized in PPE showed antibacterial activities comparable to those of AgNO3 at the same silver concentration against four pathogenic bacterial strains. The obtained PPE containing AgNPs, pectin, and other phytochemicals can be utilized further to produce antibacterial and antioxidant films in food packaging and medical applications.

Utilizing waste corn-cob in biosynthesis of noble metallic nanoparticles for antibacterial effect and catalytic degradation of contaminants

In the present study, cost-effective, and environmentally friendly fabrication of silver and gold nanoparticles was performed by using aqueous extract of waste corn-cob. The formation of the metallic nanoparticles (MNPs) was optimized by UV-Vis method. The phytoconstituents were responsible for reduction of silver and gold ions to silver nanoparticles (CC-AgNPs) and gold nanoparticles (CC-AuNPs) which were demonstrated by Fourier-transform infrared (FTIR) spectroscopy while formation of AgCl was attributed to the presence of chloride ions in the aqueous extract. The crystalline nature of the AgNPs, AgCl, and AuNPs was confirmed using the X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns. Morphological studies showed that the synthesized CC-AgNPs existed in spherical shape with the size ranging from 2 to 28 nm possessing an average value of 11 nm while CC-AuNPs were present in the multiple shapes with size ranging from 5 to 50 nm possessing an average value of 35 nm. For studies on bioactive application, the CC-AgNPs exhibited a high antibacterial activity against three bacterial strains including Salmonella typhimurium, Bacillus cereus, and Staphylococcus aureus. In addition, the catalytic efficiency of MNPs was investigated for reduction of o-, m-, p-nitrophenols, and degradation of organic dyes including Eosin Y and Rhodamine 6G. The rate constants calculated from the kinetical data revealed that the biosynthesized nanoparticles are excellent catalysts in potential applications for treatment of wastewater. Graphical abstract .

The biosynthesis of a graphene oxide-based zinc oxide nanocomposite using Dalbergia latifolia leaf extract and its biological applications

ZnO/GO nanocomposites were synthesized and their antibacterial activities assessed against various pathogens. They are potential antibacterial materials and significant anticancer activity against the MCF-7 breast cancer cell line compared to the A549 lung cancer cell line.

Interfacing green synthesized flake like-ZnO with TiO2 for bilayer electron extraction in perovskite solar cells

To improve the performance of PSCs, interfacing green synthesized flake like-ZnO nanostructure have been introduced between ETL/perovskite layer which reduces the recombination losses at the interface.

Green synthesis of copper nanoparticles from an extract of Jatropha curcas leaves: characterization, optical properties, CT-DNA binding and photocatalytic activity

The green synthesis of copper nanoparticles (CuNPs) using a leaf extract from Jatropha curcas (JC) has been documented in our present research work.