Larvicidal potential of gold and silver nanoparticles synthesized using Acalypha fruticosa leaf extracts against Culex pipiens (Culicidae: Diptera)

Plant secondary metabolites have been recently used for the synthesis of different nanoparticles. The present investigation aimed at evaluating the effect of gold (AuNPs) and silver (AgNPs) nanoparticles synthesized using Acalypha fruticosa leaf extracts to control the mosquito Culex pipiens. The A. fruticosa AuNPs and AgNPs spectra displayed their maximum absorption at 550 nm and 440 nm, respectively. The infrared spectra revealed different functional groups related to different chemical compounds. The larval mortality of aqueous leaf extract of A. fruticosa was 499.54 ppm (LC₅₀) and 1734.06 ppm (LC₉₀) after 24 h of treatment. This study revealed that AuNP (LC₅₀, 30.2 and LC₉₀, 104.83 ppm) and AgNP (LC₅₀, 52.86 and LC₉₀, 157.227 ppm) preparations were highly effective compared to the A. fruticosa extract alone and also more affordable, as a smaller amount was required. The present findings show the potential larvicidal effect of the synthesized AuNPs and AgNPs for the control of mosquito-mediated disease transmission.     

Synthesis of silver nanoparticles employing Polyalthia longifolia leaf extract and their in vitro antifungal activity against phytopathogen

The P. longifolia mediated silver (PL-AgNPs) nanoparticles are very stable and efficient. UV–Vis spectroscopy, dynamic light scattering (DLS), X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDX) were used to characterize the produced AgNPs. UV–Vis analysis showed a characteristic peak at 435 nm corresponding to surface plasmon resonance. The synthesis process was spectrophotometrically optimized for various parameters. After optimization, highly stable AgNPs were prepared using 3.0 ml of P. longifolia leaf extract, pH 7.0, 1.0 mM AgNO₃, and 60 °C. The zeta potential was measured by DLS, which showed ?20.8 mV and the PDI value was 5.42. TEM and SEM analysis shows a spherical shape of the synthesized nanoparticles, and the size was measured between 10 and 40 nm. EDX analysis showed intense peaks from silver and oxygen and small peaks from various metal atoms such as Na, P, S and Al indicating their presence in trace amounts. The average size of the PL-AgNPs was 14 nm. The phytochemical analysis shows that the presence of alkaloids, essential oils and saponins seems to be responsible for the synthesis of nanoparticles. PL-AgNPs were further investigated for their antifungal activity against Alternaria alternata. The minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC) and effect of nanoparticles on cytomorphology of A. alternata have also been reported. Biosynthesized nanoparticles have proven to be inexpensive, environmentally friendly, stable, easily reproducible, and highly effective against plant-pathogenic fungi.     

Green synthesis of silver nanoparticles using Andean blackberry fruit extract

Green synthesis of nanoparticles using various plant materials opens a new scope for the phytochemist and discourages the use of toxic chemicals. In this article, we report an eco-friendly and low-cost method for the synthesis of silver nanoparticles (AgNPs) using Andean blackberry fruit extracts as both a reducing and capping agent. The green synthesized AgNPs were characterized by various analytical instruments like UV–visible, transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The formation of AgNPs was analyzed by UV–vis spectroscopy at λ_max = 435 nm. TEM analysis of AgNPs showed the formation of a crystalline, spherical shape and 12–50 nm size, whereas XRD peaks at 38.04°, 44.06°, 64.34° and 77.17° confirmed the crystalline nature of AgNPs. FTIR analysis was done to identify the functional groups responsible for the synthesis of the AgNPs. Furthermore, it was found that the AgNPs showed good antioxidant efficacy (>78%, 0.1 mM) against 1,1-diphenyl-2-picrylhydrazyl. The process of synthesis is environmentally compatible and the synthesized AgNPs could be a promising candidate for many biomedical applications.     

Green synthesis of silver nanoparticles with Dalbergia spinosa leaves and their applications in biological and catalytic activities

The phytosynthesis of silver nanoparticles (AgNPs) by Dalbergia spinosa leaves (DSL) in aqueous extract was investigated. AgNPs were characterized by UV–visible absorption spectroscopy (UV–vis), transmission electron microscopy (TEM) and Fourier transform infra red spectrophotometry (FTIR). The results showed that the increase in the initial extract concentration at room temperature increased the mean size and widened the size distribution of the AgNPs, leading to a red shift and broadening the surface plasmon resonance absorption (439 nm). The results showed that the reducing sugars and flavonoids were primarily responsible for the bioreduction of silver ions and that their reductive capability was promoted at 36 °C. TEM analysis showed that the AgNPs were nearly spherical in shape with an average size of 18 ± 4 nm. When evaluated for in vitro antioxidant activity by DPPH, NO, hydrogen peroxide radicals, reducing power and CUPRAC assay methods in addition to anti-inflammatory activity by HBRC method, the silver nanoparticles exhibited considerably enhanced antioxidant and anti-inflammatory activity at the test doses when compared with that of the standards and the plant extract. Finally, the antibacterial activity of the AgNPs against two Gram-positive bacteria and two Gram-negative bacteria showed moderate antibacterial activity when compared with the standard and the plant extract. The synthesized silver nanoparticles were also effective in the catalytic reduction of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP).     

Green synthesis of silver nanoparticles using Citrus limon peels and evaluation of their antibacterial and cytotoxic properties

The present work aimed to synthesis silver nanoparticles (AgNPs) using biological waste products Citrus limon peels, its characterization, antimicrobial activities and the cytotoxic effect of the synthesized green AgNPs. Characterization of the prepared AgNPs showed the formation of spherical, and few agglomerated AgNPs forms as measured by UV–visible spectrophotometer. The average size of the prepared AgNPs was 59.74 nm as measured by DLS technique. The spectrum of the synthesized AgNPs was observed at 3 KeV using the EDX. On the other hand, FTIR analysis of the green synthesized AgNPs showed the presence of alcohols, phenolics, mono-substituted alkynes, aliphatic primary amines, sodium salt, amino acid, or SiOH alcohol groups. The antimicrobial studies of the formed AgNPs showed positive activity against most of the studied human pathogenic bacteria with varying degrees. Finally, the evaluation of the cytotoxic effect of the green synthesized AgNPs were done using two types of cell lines, human breast cancer cell line (MCF-7) and human colon carcinoma cell line (HCT-116). The results revealed the concentration has a direct correlation with cell viability. The 50% inhibitory concentration (IC₅₀) of MCF-7 cell line was in of 23.5 ± 0.97 µL/100 µL, whereas the HCT-116 cell line was in 37.48 ± 5.93 µL/100 µL.     

Green biosynthesis of silver nanoparticles from Annona squamosa leaf extract and its in vitro cytotoxic effect on MCF-7 cells

The biological method for the synthesis of silver nanoparticles (AgNPs) using Annona squamosa leaf extract and its cytotoxicity against MCF-7 cells are reported. The synthesized AgNPs using A. squamosa leaf extract was determined by UV–visible spectroscopy and it was further characterized by FT-IR, X-ray diffraction (XRD), Transmission electron microscopy (TEM), Zeta potential and energy dispersive spectrometric (EDS) analysis. The UV–visible spectrum showed an absorption peak at 444 nm which reflects surface plasmon resonance (SPR) of AgNPs. TEM photography showed biosynthesized AgNPs were predominantly spherical in shape with an average size ranging from 20 to 100 nm. The Zeta potential value of ?37 mV revealed the stability of biosynthesized AgNPs. Furthermore, the green synthesized AgNPs exhibited a dose-dependent cytotoxicity against human breast cancer cell (MCF-7) and normal breast epithelial cells (HBL-100) and the inhibitory concentration (IC₅₀) were found to be 50 μg/mL, 30 μg/mL, and 80 μg/mL, 60 μg/ml for AgNPs against MCF-7 and normal HBL-100 cells at 24 h and 48 h incubation respectively. An induction of apoptosis was evidenced by (AO/EtBr) and DAPI staining. Application of such eco-friendly nanoparticles makes this method potentially exciting for the large scale synthesis of nanoparticles.     

Ganoderma lucidum inspired silver nanoparticles and its biomedical applications with special reference to drug resistant Escherichia coli isolates from CAUTI

In the search for alternative therapy for infections and other ailments, metallic nanoparticles, mainly silver nanoparticles (AgNPs) synthesized through bioengineered sources are extensively explored. Fungal bioactive compounds and their nanoparticles were reported with the potential biomedical application. A medicinal mushroom Ganoderma lucidum was reported as a repository of rich medicinal properties. In the current study, silver nanoparticles were synthesized using the extracts of G. lucidum and its antimicrobial activity was tested against drug-resistant Escherichia coli isolated from the catheter used for urinary tract infection (CAUTI). The GC–MS study of G. lucidum extracts showed the presence of ethyl acetoacetate ethylene acetal with the highest area percentage of 72.2% and retention time (RT 5873). Pyridine-3-ol is the second primary compound with a peak height of 6.44% and a retention time of 2.143. The third compound is l,4-Dioxane-2,3-diol, with an area of 8.09% and RT 5450. Butylated Hydroxy Toluene [BHT] is the fourth major compound with an area of 3.32%, and 9-Cedranone constitutes the fifth position in occupying the area percentage [1.88] and height 1.56%. Pyrrole is the sixth primary compound registering an area size of 0.96% and height 2.06%. The AgNPs synthesized using G. lucidum extract were in size range 23 and 58 nm as per SEM analysis and within the range wavelength 0.556–0.796 nm as per UV–Vis spectral study. FTIR Spectroscopy and X-ray diffraction analysis (XRD) were made to characterize the formed nanoparticles. The AgNPs synthesized effectively inhibited the growth of E. coli isolated from catheter-associated urinary tract infection and showed resistance to many drugs. The antioxidant potential of the synthesized nanoparticles assessed using DPPH radical scavenging activity, EC50 (µg/ml), and ARP data showed that the prepared nanoparticles were more potent in free radical scavenging activity than the standard quercetin. The cytotoxicity effect of Ag-NPs on breast cancer cell line- MDA-MB-231 confirmed its anticancer potential. The half-maximal inhibitory concentration (IC₅₀) of Ag-NPs to inhibit 50% of the tumor was 9.2 g/mL. The synthesized GL-AgNPs was exhibited a multifocal biomedical potential.     

Comparative study of antifungal activity of two preparations of green silver nanoparticles from Portulaca oleracea extract

The green silver nanoparticles (green AgNPs) exhibit an exceptional antimicrobial property against different microbes, including bacteria and fungi. The current study aimed to compare the antifungal activities of both the crude aqueous extract of Portulaca oleracea or different preparations of green AgNPs biosynthesized by mixing that aqueous extract with silver nitrate (AgNO₃). Two preparations of the green AgNPs were synthesized either by mixing the aqueous extract of P. oleracea with silver nitrate (AgNO₃) (normal AgNPs) or either irradiation of the AgNPs, previously prepared, under ⁶⁰Co γ-ray using chitosan (gamma-irradiated AgNPs). Characterization of different AgNPs were tested by Zeta potential analyzer, Ultraviolet (UV) Visible Spectroscopy, and Fourier-Transform Infrared (FTIR) spectrometry. Three different plant pathogenic fungi were tested, Curvularia spicifera, Macrophomina phaseolina, and Bipolaris sp. The antifungal activities were evaluated by Transmission Electron Microscope (TEM) for either the crude aqueous extract of P. oleracea at three doses (25%, 50%, and 100%) or the newly biosynthesized AgNPs, normal or gamma-irradiated. With a few exceptions, the comparative analysis revealed that the irradiated green AgNPs at all three concentrations showed a relatively stronger antifungal effect than the normal AgNPs against all the three selected fungal strains. UV–visible spectroscopy of both preparations showed surface plasmon resonance at 421 nm. TEM results showed that both AgNPs were aggregated and characterized by a unique spherical shape, however, the gamma-irradiated AgNPs were smaller than the non-irradiated AgNPs (0.007–0.026 µM vs. 0.009–0.086 µM). TEM photographs of the fungal strains treated with the two AgNPs preparations showed flaccid structures, condensed hyphae, and shrunken surface compared with control cells. The data suggested that the biosynthesized P. oleracea AgNPs have antifungal properties against C. spicifera, M. phaseolina, and Bipolaris sp. These AgNPs may be considered a fungicide to protect different plants against phytopathogenic fungi.     

Antioxidant,antibacterial and cytotoxic potential of silver nanoparticles synthesized using terpenes rich extract of Lantana camara L. leaves

Several attempts have been made for green synthesis of silver nanoparticles (AgNPs) using different plant extracts. Present study revealed that, antioxidant, antibacterial and cytotoxic AgNPs were synthesized using terpenes-rich extract (TRE) of environmentally notorious Lantana camara L. leaves. AgNPs were characterized by advanced techniques like UV–Visible and Infra red spectroscopy; XRD, SEM techniques as terpenes coated sphere shaped NPs with average diameter 425 nm. Further, on evaluation, AgNPs were found to exhibit dose – dependent antioxidant potential, good to moderate antibacterial activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa; and toxicity on Brine shrimp (A. salinanauplii) with LD₅₀ value 514.50 µg/ml.     

Green synthesis,characterization and biological activity of Solanum trilobatum-mediated silver nanoparticles

Biologically inspired synthesis of nanoparticles was found to be more attractive in metal nanoparticle synthesis. The present study reported an in-situ biogenic synthesis of silver nanoparticles (AgNPs) using Solanum trilobatum aqueous leaf extract. On this basis, the aqueous leaf extract of S. trilobatum acted as a reducing agent and stabilizing agent to synthesize highly stable AgNPs at ambient temperature. Eventually, the synthesized and stabilized AgNPs surface plasmon resonance was near 430 nm through a UV–visible (UV–vis) spectrophotometer. Here, the stability of the silver colloids monitored through zeta potential and mean particle size was evaluated through diffraction light scattering (DLF). Further, the average particle size was found to be 27.6 nm and spherical, confirmed with transmission electron microscopy (TEM). Also, colloidal AgNPs and aqueous extract are found to be rich sources of antioxidants and exhibit higher free radical scavenging ability. Thus, efficient inhibition with COX1 and COX2 enzymes and the protective effect with human red blood cell (HRBC) membrane stability showed significant results. These features are promising, suggesting the possibility of the AgNPs to be useful to disease-modifying for treating inflammatory disorders and associated complications.