Preparation Of Silver Nanoparticles Research Articles

Sustained-release, antibacterial, adhesive gelatin composite hydrogel with AgNPs double-capped with curdlan derivatives

In this work, carboxymethylated curdlan (CMCD) was utilized as a capping and stabilizing agent for the green synthesis of silver nanoparticles. Subsequently, quaternized curdlan (QCD) was introduced as the second capping layer through electrostatic attraction, leading to the preparation of double-capped silver nanoparticles (AgNPs@CQ). The successful synthesis of silver nanoparticles was characterized using UV–vis, FTIR, XRD, TEM, and DLS. AgNPs@CQ were incorporated into gelatin and a AgNPs@CQ/Gel composite hydrogel was obtained. The incorporation of AgNPs@CQ imparts excellent antibacterial properties to the composite hydrogel, thereby enhancing its antimicrobial efficacy. The presence of double-capping layers significantly retards the release rate of silver, contributing to prolonged antimicrobial activity. The MTT and live/dead fluorescence staining results demonstrate that the gelatin hydrogel incorporating double-capped AgNPs exhibits enhanced cell viability compared to the one incorporating single-capped AgNPs. Additionally, the composite hydrogel exhibits remarkable mechanical strength and adhesive performance. The AgNPs@CQ/Gel composite hydrogel demonstrates a cost-effective and facile preparation, showing significant potential in the field of dressings.

Effect of “corona-core” structuring of poly(1-vinyl-1,2,4-triazole)–poly(acrylic acid)-Ag(I) interpolymer complexes on the radiation-induced preparation and stability of silver nanoparticles

Interpolymer complexes (IPC) of water-soluble polymers can be promising matrices for the synthesis of metal colloids. In this work, silver nanoparticles were obtained via radiation-induced reduction (under X-ray irradiation) of complexes based on poly (1-vinyl-1,2,4-triazole) (PVT) and poly (acrylic acid) (PAA) containing Ag+ ions. Particular attention was paid to the role of the supramolecular structure in the formation of nanoparticles. Combined dynamic light scattering and electrophoretic mobility measurements have revealed that, in pH range 5.5–7, micro-scale aggregates of the initial PVT-PAA-Ag(I) IPC transform into nano-sized particles consisting of a PVT-Ag(I) core electrostatically stabilized by PAA loops and tails forming a corona. It was explicitly demonstrated for the first time that such transformation of IPC aggregates can significantly enhance the efficiency of AgNPs formation. In particular, using UV-VIS spectroscopy and transmission electron microscopy, we have shown that at pH 7.0 the core of the “corona-like” form of the PVT-PAA-Ag(I) complex ensures the radiation-induced generation of AgNPs with a narrow size distribution due to the strong affinity of triazole groups to the metal surface. At the same time, the localization of the excessive negatively charged carboxylate groups in the outer part of the complex provides a long-term colloidal stability of the prepared AgNPs.

Green synthesis of silver nanoparticles using food supplement from Avena sativa L., and their antioxidant, antiglycation, and anti-aging activities: In vitro and in silico studies

Food supplement of Avena sativa L. dry extract (AsDE) is produced with green leaves of wild oats and it is commonly used in patients with cognitive disorders and muscle deficits. These symptoms and pathologies can be promoted and/or aggravated by oxidative stress and protein glycation. In order to prevent or treat these disorders, new formulations that could enhance and benefit AsDE have been developed and the formation of metallic nanoparticles by green synthesis has shown to be an alternative. Thus, this study aimed to prepare silver nanoparticles (AgNPs) by green synthesis using AsDE and characterize these AgNPs. Besides, it aimed to evaluate in vitro antioxidant and antiglycation activities of AsDE and AgNPS, and analyze in vitro and in silico inhibitory action on aging enzymes (collagenase, elastase, and tyrosinase). UV–visible spectroscopy, Zeta potential and scanning transmission electron microscopy were used to characterize AgNPs. Antioxidant activity was determined by DPPH free radical scavenging, ferric ion reducing power (FRAP), lipid peroxidation inhibition, ABTS radical scavenging, and oxygen radical absorption capacity (ORAC). Molecular docking analyses were performed to evaluate interactions between the major compounds of AsDE and aging enzymes or DNA. Antioxidant tests demonstrated antioxidant activity of 19.67 % for AsDE and 42.98 % for AgNPs in DPPH test; and 115.67 µM Trolox Equivalent (TE)/g for AsDE and 554.33 µM TE/g for AgNPs in FRAP test. In addition, AsDE and AgNPs inhibited 25.40 % and 11.33 % of lipid peroxidation, respectively, and presented 255.22 µM TE/g for AsDE and 317.44 µM TE/g for AgNPs in ABTS test. AsDE and AgNPs exhibited antioxidant potential observed in ORAC assay. In addition, AsDE presented inhibitory action on collagenase, elastase and tyrosinase activities (78.23 %, 68.14 % and 62.27 % inhibition, respectively). Antiglycation tests demonstrated that bovine serum albumin exposed to ribose and treated with AsDE at 0.5 mg/mL exhibited the highest percentage of free amino groups (45.21 %), while samples treated with AgNPs showed 35.41 % free amino groups. On the other hand, AgNPs exhibited the highest percentage of inhibition of advanced glycation end-products formation (85.75 %), which did not differ from aminoguanidine, a known antiglycation agent. Besides, relative electrophoretic mobility assay demonstrated that samples treated with AsDE at 0.1 mg/mL or AgNPs showed antiglycation activity comparable to aminoguanidine. The in silico assays showed interactions between the major compounds of AsDE and aging enzymes or DNA. Therefore, results represent an important indicator for the development and discovery of new nanostructured pharmaceutical and cosmetic formulations using plants and their bioactive compounds.

Preparation of Green Silver Nanoparticles and Eco-Friendly Polymer-AgNPs Nanocomposites: A Study of Toxic Properties across Multiple Organisms.

This article focuses on the eco-friendly (green) synthesis of silver nanoparticles (AgNPs) and their incorporation into a polymer matrix. For AgNPs synthesis, Lavandula angustifolia (lavender) leaf extract was used as a reducing and stabilizing agent, and as a silver precursor, AgNO3 solution with different concentrations of silver (50, 100, 250, and 500 mg/L) was used. Prepared AgNPs colloids were characterized using UV-vis spectrophotometry, transmission electron microscopy (TEM), and X-ray diffraction (XRD). The spherical morphology of AgNPs with an average size of 20 nm was confirmed across all samples. Further, the antimicrobial properties of the AgNPs were evaluated using the disk diffusion method on algae (Chlorella kessleri) and the well diffusion method on bacteria (Staphylococcus chromogenes, Staphylococcus aureus, and Streptococcus uberis), along with root growth inhibition tests on white mustard (Sinapis alba). Polymer composite (PVA-AgNPs) was prepared by incorporation of AgNPs into the polymer matrix. Subsequently, non-woven textiles and thin foils were prepared. The distribution of AgNPs within the nanocomposites was observed by scanning electron microscopy (SEM). Antibacterial properties of PVA-AgNPs composites were analyzed on bacteria Streptococcus uberis. It was found that not only AgNPs showed good antimicrobial properties, but toxic properties were also transferred to the PVA-AgNPs nanocomposite.

Utilizing Biomolecule-Rich Citrus Fruit Waste as a Medium for the Eco-Friendly Preparation of Silver Nanoparticles with Antimicrobial Properties

An ample amount of fruit waste is generated as agro-industrial waste, leading to significant nutritional, economic, and environmental challenges. Fruit peels are rich in many valuable bioactive compounds with the potential for developing nanoparticles. This study examined fresh juices of two citrus fruit peel wastes (Citrus sinensis: C. sinesis and Citrus limon: C. limon) for antioxidants and total protein. Then, we investigated their ability to produce silver nanoparticles, which were further analyzed for anti-microbial activity against thirteen pathogenic microbes. Both Citrus peel juices were rich in secondary metabolites. The formation of Ag nanoparticles was initially confirmed by UV-vis spectroscopy, with peaks at 400 nm for C. sinensis peel Ag nanoparticles and 430 nm for C. limon peel Ag nanoparticles. Further characterization was conducted using zeta sizer, zeta potential, Transmission Electron Microscopy (TEM), Scanning Electron Microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX) and Fourier transform infrared (FTIR) spectroscopy. The antimicrobial activity was tested using the well diffusion method against 11 bacterial strains (five Gram-positive and six Gram-negative) and two fungal strains of Candida. TEM and SEM results revealed a spherical shape, with an average diameter of about 13 nm for C. sinensis and 21 nm for C. limon Ag. EDX confirmed the presence of silver in both nanoparticles. The FTIR spectrum of the extract indicated the presence of biomolecules, which facilitated the reduction and capping of the synthesized Ag nanoparticles. The prepared nanoparticles showed remarkable antimicrobial activity, but the nanoparticles from C. sinensis exhibited stronger antibacterial properties because of their smaller size. Citrus peel waste is a suitable medium for the eco-friendly production of silver nanoparticles.

Synthesis of silver nanoparticles assisted by aqueous root and leaf extracts of Rhus chinensis Mill and its antibacterial activity

In the present study, silver nanoparticles were synthesized using aqueous root and leaf extracts of Rhus chinensis Mill. This study aimed to undertake the green synthesis of silver nanoparticles utilizing plant extracts in an eco-friendly, cost-effective, and more efficient manner with its antibacterial application. The prepared silver nanoparticles (AgNPs) were characterized by using different techniques. Such as ultraviolet–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FT-IR), x-ray diffraction spectroscopy (XRD), field emission-scanning electron microscopy (FE-SEM), and energy dispersive X-ray (EDX). The color changes from yellowish to reddish brown can be visualized and it indicates the formation of silver nanoparticles. The UV–Vis absorption peak shown by the synthesized AgNPs assisted by root and leaf extract was at 443 nm and 440 nm respectively. The functional group present in plants' secondary metabolites may act as capping and stabilizing agents, indicated by the shifting and disappearing of the peak in the plant extracts and the extracts-assisted synthetic nanoparticles. The crystallite size of synthesized AgNPs assisted by the root and leaf extracts of Rhus cinensis was found to be 11.01 nm and 13.39 nm respectively, while with the help of FE-SEM image the shape and particle size of synthesized AgNPs root and leaf extract was found spherical with particle diameter of 54.40 nm and 30.89 nm respectively. The presence of an intense silver component was confirmed by EDX analysis which showed an intense peak at around 3 Kev and other elements like Cl, O, C, and N were also reported in synthesized AgNPs. Both the plant extracts assisted synthesized AgNPs showed higher zones of inhibition (ZOI) against both the Gram-positive and Gram-negative bacteria. The results of the study indicate the potential benefit of synthesized silver nanoparticles using Rhus chinensis root and leaf extracts for biomedical purposes.

Green Synthesis of Silver Nanoparticles with Snake Fruit Peel Extract: A Preliminary Study For Optimization of The Preparation Technique

In Indonesia, the pulp of snake fruit is consumed while the peel remains unused. In this context, the phytochemical content of snake fruit aqueous extract was used as a reducing and capping agent in the preparation of silver nanoparticles (AgNPs). According to the phytochemical screening, snake fruit peel containing alkaloids, flavonoids, tannins, saponins, and polyphenols was used to synthesize AgNPs. Therefore, this research aimed to optimize the synthesis of AgNPs using snake fruit peel extract (Salacca zalacca) in terms of synthesis time, temperature and phytochemical screening. AgNPs were successfully synthesized using a volume ratio of 2:15 (20 mL of 1.00 mM AgNO3 to 150 mL of snake fruit peel extract) in a sealed container in a dark room. Furthermore, characterization was carried out using a UV-Vis spectrum and Fourier Transform Infrared Spectroscopy (FTIR). The UV-Vis spectrum characterization in a solution incubated for 30 minutes at 30 °C with a concentration of 1.00 mM AgNO3 was differentiated at a wavelength of 410 nm with an absorbance of 2.361. According to the FTIR characterization, there was an increase in the intensity of the O – H functional groups in the AgNPs solution compared to snake fruit peel extract. The results showed that the synthesis of AgNPs from snake fruit peel extract was optimal at a concentration of 1.00 mM AgNO3 at 30 °C and 30 minutes of incubation.

Plant-assisted green preparation of silver nanoparticles using leaf extract of Dalbergia sissoo and their antioxidant, antibacterial and catalytic applications.

Plant-mediated preparation of silver nanoparticles (AgNPs) is thought to be a more economical and environmentally benign process in comparison to physical and chemical synthesis methods. In the present study, the aqueous leaf extract of Dalbergia sissoo was prepared and utilized to reduce silver ion (Ag+) during the green synthesis of silver nanoparticles (DL-AgNPs). The formation of DL-AgNPs was verified using UV-Vis spectra, exhibiting the surface plasmon resonance (SPR) band at around 450nm. FT-IR analysis revealed the kinds of phytochemicals that serve as reducing and capping agents while DL-AgNPs are being synthesized. Analysis of scanning electron microscope (SEM) and high-resolution transmission electron microscopy (HR-TEM) images verified the development of spherical and oval-shaped DL-AgNPs, with sizes ranging from 10 to 25nm. The stability and particle size distribution of synthesized DL-AgNPs were ensured by zeta potential and DLS (dynamic light scattering) investigations. Additionally, X-ray diffraction (XRD) analysis confirmed the crystalline nature of DL-AgNPs. In antioxidant experiments, DL-AgNPs demonstrated significant scavenging capacities of DPPH and ABTS radicals with EC50 values of 51.32 and 33.32μg/mL, respectively. The antibacterial activity of DL-AgNPs was shown to be significant against harmful bacteria, with a maximum zone of inhibition (21.5 ± 0.86mm) against Staphylococcus aureus. Furthermore, DL-AgNPs exhibited effective catalytic activity to degrade environment-polluting dyes (methylene blue, methyl orange, and Congo red) and toxic chemicals (p-nitrophenol). The results of all these studies suggested that DL-AgNPs made from the leaf extract of Dalbergia sissoo have merit for application in the environmental and biomedical fields.

Catalytic Reduction of 4-Nitrophenol and Methylene Blue with Silver Nanoparticles Decorated with Drymoglossum piloselloides Extract

Drymoglossum piloselloides is one of the epiphytic plants that is commonly found in Southeast Asia region. In this study, the ethanol extract of D. piloselloides plant has been used in the green synthesis of silver nanoparticles. The synthesized silver nanoparticles were characterized by ultraviolet-visible (UV-Vis) spectrophotometry, X-ray diffraction (XRD),Fourier-transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM) measurements. The UV-Vis spectrum of silver nanoparticles showed a maximum wavelength at 453 nm. The XRD measurement showed the silver nanoparticles peaks at 38.38°, 44.60°, 64.76°, and 77.62°. The FTIR spectra provided evidence of the interaction between silver and chemicals in the plant extract as a weak signal at 682 cm-1. Meanwhile, TEM revealed an average size of 12.63nm. The synthesised silver nanoparticles were utilised for the reduction of 4-nitrophenol with a conversion percentage of up to 100% with a reduction reaction rate constant of 7.104 s-1. In addition, methylene blue was also successfully reduced with the synthesised silver nanoparticles as the catalyst with a reduction reaction rate constant (k) of 21.150 s-1. This study highlights the superior advantage of utilizing ethanolic extract of D. piloselloides to prepare silver nanoparticles with promising catalytic reduction purposes.

Green synthesis of Poria cocos polysaccharides-silver nanoparticles and their applications in food packaging

To reduce pollution caused by traditional plastic packaging and preparation of silver nanoparticles (AgNPs), this work aims to develop biological macromolecular packaging films with green synthesized AgNPs. In this study, a novel P. cocos polysaccharide (PCP) with a unique monosaccharide composition was extracted from Poria cocos (Schw.) Wolf. Then, this polysaccharide containing 24.68 % rhamnose was used as a stabilizer for the green synthesis of PCP-AgNPs for the first time. PCP-AgNPs exhibited excellent antibacterial activity against P. aeruginosa, E. coli, and S. aureus, with the highest antibacterial activity against E. coli (inhibition zone diameter = 11.14 ± 0.79 mm). Subsequently, PCP-AgNPs/chitosan (CS) film was successfully prepared by incorporating PCP-AgNPs into the CS film solution. Several experiments demonstrated that the addition of this nanomaterial promoted the formation of noncovalent interactions between CS and PCP-AgNPs, resulting in a more regular and denser film. Compared to the CS film and control group, the PCP-AgNPs/CS film significantly maintained the quality indexes of strawberries. Therefore, this composite film successfully extended the shelf life of strawberries. Regarding safety, these packaging films were not cytotoxic toward RAW264.7 cells. In conclusion, the environmentally friendly PCP-AgNPs/CS film has the potential to replace some traditional food packaging materials.

Silver Nanoparticles Produced In Vitro by Berberis vulgaris Fruit and Their Antioxidant, Antimicrobial and Ex Ovo Irritation Potential Study

Green synthesis was successfully used for silver nanoparticles (Ag NPs) preparation using Berberis vulgaris aqueous extracts. The ultraviolet and visible (UV–Vis) spectroscopy, photon cross-correlation spectroscopy (PCCS), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) techniques were used for characterization of the Ag NPs and confirmed the presence of Ag(0) in nanoparticles. The bimodal morphology was discovered, namely, the larger particles had elongated shape and size around 200 nm, while the smaller ones were spherical with a size of up to ten microns. All the nanoparticles (NPs) showed antioxidant activity against radical DPPH and ferric-reducing antioxidant power. The Ag NPs possess antibacterial effects against Escherichia coli and Staphylococcus aureus comparable to silver nitrate solution. In addition, also irritation potential of the produced Ag NPs has been investigated ex Ovo and no irritation of vessels and their surroundings was found, which shows the harmless character of the products.

Preparation and application of silver nanoparticle capped carbon dots composite as fluorescent probe for cobalt determination in vitamin B12 supplement samples

A simple and economical material of fluorescence nanocomposite was developed to quantify vitamin B12 through cobalt(II) ion measurement. The material was derived from carbon dots capped with silver nanoparticles, forming spherical AgNPs@CDs composite with the average diameter of 8.7 nm, expressing unique optical properties, and was used as an optical probe for Co(II) ion determination. The synthesized AgNPs@CDs showed a maximum absorption peak at the wavelength of 406 nm, while their fluorescence peak appeared at the wavelength of 526 nm under the excitation wavelength of 406 nm. The nanocomposites exhibited stable fluorescence with IC50 value against human cholangiocyte cell line of 137.7 ppm after 24 h of the treatment. The interaction between Co(II) ions and AgNPs@CDs effervesced molecular oxygen and caused fluorescence quenching of the composite material. The optimum conditions for Co(II) ion detection were pH 10, volume ratio between AgNPs@CDs and Co(II) ion of 0.10:0.90, and reaction time of 30 min. The linearity range based on the Stern–Volmer plot was 0.05–10.00 ppm, and the limit of detection and limit of quantification were 0.032 ppm and 0.095 ppm, respectively. The developed approach was used to determine the extracted Co(II) ions in commercial vitamin B12 supplement samples and their spiked extracts. The results showed good agreement with those from a conventional method of atomic emission spectrometry, and acceptable range of recovery from 90.0 to 105.0 % was obtained. The fluorescence quenching mechanism of the AgNPs@CDs was elucidated based on the characterization information from several analytical techniques, and electrocatalytic reaction between the nanocomposite and Co(II) species was proposed.

A nanocomposite hydrogel loaded with Ag nanoparticles reduced by aloe vera polysaccharides as an antimicrobial multifunctional sensor

Developing high-performance hydrogels with anti-freeze, and antimicrobial properties is crucial for the practical application of flexible sensors. In this study, we prepared silver nanoparticles (AgNPs) with aloe polysaccharide (AP) as a reducing agent. Then, the AP/AgNPs were added to a system of polyvinyl alcohol and borax crosslinked in water/glycerol to obtain a multifunctional conductive hydrogel. The incorporated AgNPs improved the conductivity (0.39 S/m) and mechanical properties (elongation at break: 732.9 %, fracture strength: 1267.6 kPa) of the hydrogel. In addition, resultant hydrogel exhibited potential for sensing strain, temperature, and humidity. When used as a strain sensor, the hydrogel system exhibited low detection limit (0.1 %), and fast response (0.08 s). The resistance of the hydrogel decreased with an increase in the absorbed moisture content, enabling humidity detection (25–95 %) to monitor breathing status. As a temperature sensor, the hydrogel supported a wide detection range (−50 to +90 °C) and sensitivity (−30–0 °C, temperature coefficient of resistance (TCR) = −5.64 %/°C) to detect changes in the ambient temperature. This study proposes a simple method for manufacturing multifunctional hydrogel sensors, which broadens their application prospects in wearable sensing and electronic products.

Preparation of silver nanoparticle functionalized amphiphilic bio-carbon particles and its bacteria-killing effect and blood compatibility

Catheter-related bloodstream infection (CRBSI) has become the bacterial infection of special concern considerably causing the prolonged hospitalization and the delayed clinical treatment. In this paper, silver nanoparticles (AgNPs) were stabilized in sodium polyethylene sulfonate (PVS) solution (PVS-Ag). Amphiphilic bio-carbon particles (ACPs) were synthesized from S. cerevisiae cells and employed as the matrix. Chitosan (CS) modification on ACPs (ACPs-CS) facilitated the PVS-Ag grafting with stability and efficiency. Results of morphologic analysis indicated that CS and PVS-Ag modification distinctly changed the morphological-structural properties of the ACPs surface. Surface potentials of ACPs, ACPs-CS and the obtained functionalized bio-carbon material (ACPs-CS-PVS-Ag) were −38.0 mV, +36.1 mV and −53.1 mV, respectively, revealing that the anionic groups enriched on the PVS-Ag surface had largely consumed the amino groups around the surface of ACPs-CS. Results from X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) further demonstrated that AgNPs had successfully attached to the ACPs-CS surface. The anionic amphiphiles (ACPs-CS-PVS-Ag) exerted high blood-compatibility and bio-safety, especially the broad-spectrum antibacterial property at the microgram scale. In conclusion, the ACPs-CS-PVS-Ag assembly has potential value in the development of biomedical devices and/or implants for the safe-and-effective elimination of bacterial infections.

Honey-assisted synthesis and properties of silver nanoparticles in aqueous solution and inside supramolecular aggregates. The Cassyopea® effect

In this work we introduce supramolecular aggregates named Cassyopea®, acronym of combined and sustainable synthesis of payload-enriched aggregates from the method used for their preparation. Herein, Cassyopea® were described as reactors and carriers for silver nanoparticles (AgNPs) obtained from honey according to eco-friendly conditions. Spherical, monodisperse, and negatively charged NewAgNPs®, acronym of natural ecosustainable way AgNPs, having a mean size of 30 nm and high stability over time were prepared in aqueous solution. The successful synthesis of NewAgNPs® inside Cassyopea® was demonstrated by UV–vis spectroscopy, emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray (EDX) analysis. The protective effect of Cassyopea® on NewAgNPs® against the oxidation induced by H2O2 was kinetically determined in the Fenton-like reaction suggesting that the investigated nanoparticles tend to be located in the aqueous core of the investigated aggregates. Furthermore, microbiological assays revealed the tendency of Cassyopea® to preserve the biological activity of NewAgNPs® against Gram-positive and Gram-negative bacteria. The preparation of silver nanoparticles directly into supramolecular aggregates instead of their loading in preformed state is unprecedented, and the data reported for NewAgNPs® and Cassyopea® highlight promising applications in nanotechnology.

Insecticidal Activity of Green Synthesized Silver Nanoparticles from Pelargonium Citronellum against Citrus Mealybug, Planococcus Citri

Planococcus citri is a common insect pest that poses a serious threat to citrus crops. Treatment of Planococcus citri with chemical pesticides causes harm to humans, animals, and the environment. This study aimed to use silver nanoparticles as potential alternatives to control this agricultural insect pest. Silver nanoparticles (AgNPs) have been identified using X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy, and scanning electron microscopy (SEM). An absorbance peak at 425 nm in the UV-Vis spectrum showed the existence of AgNPs due to plasmon resonance. XRD patterns verified that the AgNPs possess a highly crystalline structure. SEM imaging showed that the AgNPs were spherical in shape with an average size of 12.4 nm. Toxicological tests of the prepared silver nanoparticles showed they are effective in insecticidal activities in different stages of the mealybug. Using the synthesized silver nanoparticles for more than 72 hours of treatment at a concentration of 100 ppm resulted in the highest killing rates of 40.0, 68.0, and 70.0% for the development of three stages of the mealybug, including eggs, the first age of nymphs, and adult females, respectively. The lowest percentage of the insecticidal efficacy of silver nanoparticles was recorded at a concentration of 5 ppm, reaching 62.75 and 4.6 % after 3 and 7 days, respectively. To our knowledge, it is noteworthy to report that nanoparticles were successfully synthesized from the extract of Pelargonium citronellum for the first time. The results have demonstrated the potential of natural extracts as a source of nanoparticles to manage mealybugs.

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 480nm. 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 20-25nm. 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 6.25µg/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.

Antibacterial and anticancer activity of green synthesised silver nanoparticles using polysaccharides extracted from the marine alga Portieria hornemannii

The increasing incidence of cancer cases and multi-drug-resistant bacteria, which are major threats to humankind, forces the research world to innovate new molecules to deal with them. The main aim of the present work is to prepare silver nanoparticles using macroalgal polysaccharides and to study biological activities. The silver nanoparticles (NPs) were prepared using polysaccharides extracted from the marine macro alga Portieria hornemannii by stirring them with 1 mM silver nitrate after 24 h at 90 ºC. The formed silver nanoparticles were characterized using UV-visible spectrophotometry, Fourier transform infrared spectroscopy (FTIR) analysis, Transmission Electron Microscopy (TEM) analysis, selected-area electron diffraction (SAED), and Energy Dispersive X-ray (EDX) analysis. UV-visible spectrum analysis revealed a surface plasmon peak at 380 nm, showing the development of silver nanoparticles. The nanoparticle size varied between 40 and 50 nm and the functional group was analyzed using FT-IR spectrum. The broadband was observed at 3304 cm-1 (hydroxyl and amino group) and the narrow band was observed at 2907 cm-1 (C–H stretching vibration), 1657 cm-1 (stretching of carbonyl groups), and 1001 cm-1 (C–O stretching vibration). The crystalline nature of silver NPs was confirmed by SAED. EDX analysis reveals the purity and the chemical composition of silver NPs. Nanoparticles were highly effective against Proteus mirabilis (24 mm zone of inhibition) and Bacillus substilis (24 mm zone of inhibition). The anticancer activity of the silver nanoparticles tested against colorectal adenocarcinoma cell lines increased at increasing concentrations of nanoparticles.

Preparation of Silver Nanoparticles Deposited on TEMPO-Oxidized Cellulose Nanofibers

Silver nanoparticles (AgNPs) were synthesized by a chemical method in which cellulose nanofibers (CNFs) extracted from pineapple leaves served as a stabilizing and reducing agent. In this study, pineapple leaves were oxidized by the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation with sodium hypochlorite (NaClO) to obtain CNFs. After the oxidation, the transformation from hydroxyl groups to carboxylate groups of cellulose was confirmed by Fourier-transform infrared spectroscopy (FTIR), and TEMPO-oxidized CNFs with a higher carboxylate content were obtained. Then, TEMPO-oxidized CNFs with a carboxylate content of 2.49 mmol/g and non-oxidized CNFs with a carboxylate content of 0.68 mmol/g were used as a reducing agent to synthesize AgNPs. The formation of AgNPs was confirmed by color changes of the Ag solutions from white to yellow. Furthermore, AgNPs with an average diameter of 76.5 ± 22.15 nm were obtained when TEMPO-oxidized CNFs were used as a reducing agent, while non-oxidized CNFs generated AgNPs with a larger particle size of 181.2 ± 66.16 nm. This suggested that the TEMPO-oxidized CNFs could be used as a stabilizing and reducing agent for the synthesis of AgNPs with smaller diameters.

Preparation of silver nanoparticles modified SnO2 humidity sensor for tobacco storage environment detection

In this paper, silver nanoparticles (AgNPs) modified SnO2 (Ag/SnO2) nanocomposite with excellent humidity performance was prepared by hydrothermal method. Experimental results demonstrate that AgNPs enhance the performance of the SnO2 humidity sensor, which is primarily attributed to increase the oxygen vacancies on the surface of the SnO2 through the incorporation of AgNPs. Density functional theory (DFT) demonstrated that more oxygen vacancies can enhance the chemical and physical adsorption energy of water molecules by SnO2, and decompose more water molecules into conductive H+ ions: simultaneously, the response/recovery times and hysteresis error of SnO2 are reduced. Compared to the SnO2 humidity sensor, Ag/SnO2 exhibits low humidity hysteresis (2.7%), relatively short response/recovery time (5/8 s) and high sensitivity (24292.3). Furthermore, the Ag/SnO2 humidity sensor employed in this study has successfully demonstrated its efficacy in detecting humidity levels within tobacco storage environments, which expands the potential applications of humidity sensors.