Optimization of green synthesis parameters for silver nanoparticles using Cleistocalyx operculatus via Box–Behnken design and antibacterial evaluation

The present paper focuses on the synthesis of silver nanoparticles using with different leaf extract concentrations of Vitex negundo. The biosynthesized nanoparticles were characterized by UV-vis absorption spectrophotometry, fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray, atomic force microscopy, transmission electron microscopy, photoluminescence and zeta potential techniques. The formation of silver nanoparticles was confirmed by the surface plasmon resonance absorption peak at 423 nm in UV-vis absorption spectra of the synthesized silver nanoparticles. The fourier transform infrared spectroscopy indicates flavonoids as a potential reduced agents. Field emission scanning electron microscopy shows the synthesized silver nanoparticles are in spherical shape. Energy dispersive X-ray spectroscopy shows the strong peak belongs to silver, and it confirms the formation of Ag NPs. X-ray diffraction spectra of synthesized silver nanoparticles exhibit they are in face centered cubic crystalline structure. The photoluminescence spectra of synthesized silver nanoparticles show their emission peak at 489-481 nm and the emission intensity is proportional to the different concentrations of leaf extract. The spherical shaped silver nanoparticles are observed by atomic force microscopy technique. The zeta potential value is observed at -13.5 mV, which shows the synthesized silver nanoparticles are incipient instability. The antimicrobial activity of the synthesized nanoparticles is studied using the disc diffusion method, which indicates that both Gram positive and Gram negative microorganisms have been affected by the silver nanoparticles. The observed antibacterial activity could be find important applications in medicine, biology and industry.

Biofabrication of Centella asiatica mediated metal (Silver and Iron) nanoparticles and their enhanced antimicrobial, anticancer activity in retinoblastoma Y79 cancer cells

In this work the effectiveness of electromagnetic radiation for the formation of spherical silver nanoparticles in water solution is studied. Silver nanoparticles colloid was synthesized by photostimulated reduction of Ag ions in silver salt aqueous solution stabilized by sodium citrate. The formation of silver nanoparticles in test solution was confirmed by spectrophotometry. The elemental composition of the silver colloid obtained by photoreduction technique was defined. The size and shape of the formed nanoparticles was determined by transmission electron microscope (TEM). Besides, the theoretical modeling of spectral characteristics were carried out by dipole equivalence method and discrete dipole approximation (DDA). It is shown that electromagnetic irradiation is promising approach for the formation of spherical silver nanoparticles in solution.

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

The coconut rhinoceros beetle, Oryctes rhinoceros (L), has been one of the major pests of coconut in India and other coconut producing countries causing direct or indirect losses to the crop. It can be controlled by eliminating the places where they breed and by manually destroying adult and immature (larvae). Botanical insecticides are relatively safer, degradable and are readily available source of biopesticides. Biosynthesis of pesticides from plant extracts is most promising approach for pest control. The present investigation aims to find out the possibility of eco-friendly management of the pest Oryctes rhinoceros by incorporating with silver nanoparticle synthesized from neem plant extracts. The silver nanoparticles (AgNPs) were synthesized by using aqueous extracts of Azadirachta indica. Formation of silver nanoparticles was observed by colour change of the solution, UV, FT-IR and SEM analysis. The Larvae is treated against different concentrations of plant extract and silver nanoparticles solution. 100% larval mortality was observed in higher concentration of silver nanoparticle solution. This result concluded that both silver Nanoparticles and leaf extract have larvicidal properties but Silver nanoparticles are more efficient and it serves as an alternative to synthetic insecticides for controlling harmful pest larvae. Hence the synthesized silver nanoparticles from the A.indica can be used as potential biolarvicidal agent against Oryctes rhinoceros.

The present report describes an efficient method for bioengineering and characterization of silver nanoparticles (AgNPs) using aqueous leaf extracts of Solanum nigrum and its antibacterial as well as antibiofilm activity against multidrug resistant (MDR) human pathogens. The leaf extract was prepared using microwave irradiation method and used as potential reducing as well as stabilizing agent for synthesis of AgNPs. The formation of silver nanoparticles was monitored by UV–Visible spectra analysis at 428 nm. Fourier transform infrared spectroscopy analysis confirmed the presence of various functional biomolecules loaded on AgNPs and XRD results indicated the crystalline nature of the synthesized silver nanoparticles. Bioengineered silver nanoparticles were found to be cuboidal shape detected by scanning electron microscopy analysis. EDX spectrum showed the presence of strong signal for silver ions in the nanoparticles. The average particle size was found to be 20 nm. The synthesized silver nanoparticles exhibited potential antibacterial as well as antioxidant activity against Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Pseudomonous aeruginosa, Klebsiella pneumoniae and Proteus valgaris. In addition, biofabricated AgNPs showed significantly higher rate of antibiofilm activity against two different biofouling bacterial strains viz., P. aeruginosa and S. epidermidis. The present study highlighted the effective method for the synthesis of biomolecules-loaded silver nanoparticles and their potential antibacterial, antioxidant as well as antibiofilm activity against gram-positive and gram-negative clinically isolated human pathogens. Results showed that bioengineered AgNPs could be used as nanodrug for the treatment of MDR bacterial infections caused by biofilm with high efficiency.

Natural products are widely used in the synthesis of various types of metallic nanoparticles including silver nanoparticles. Tualang honey is one of the potential natural products which is rich in polyphenols and antioxidant capacity. This study aims to synthesise and characterise the silver nanoparticles by using Tualang honey through green method and evaluate their antioxidant activities. The formation of silver nanoparticles was examined by visual observation and further confirmed by UV-Visible spectrophotometer. The characterisation of silver nanoparticles was determined by using x-ray diffraction, fourier transform infrared spectroscopy, field emission scanning electron microscopy and transmission electron microscopy analysis. The in vitro antioxidant activity of silver nanoparticles was evaluated by 1,1-diphenyl-2-picrul hydrazyl and ferric reducing antioxidant power assays. The synthesis was confirmed physically through the colour changes from light brown to dark brown which indicates the reduction of silver ion to silver nanoparticles. UV-Visible spectrum results showed the highest absorbance peak at 410 nm. X-ray diffraction results showed that the face-centred cubic crystalline shaped nanoparticles were formed. Fourier transform infrared spectroscopy results revealed the available functional groups that act as capping and stabilising agents for the silver nanoparticles. Field emission scanning electron microscopy analysis exhibited the spherical shape and transmission electron microscopy confirmed the size range of silver nanoparticles of 22 nm. The silver nanoparticles exhibited remarkable antioxidant activity with 1,1-diphenyl-2-picrul hydrazyl and reducing antioxidant power values of 95.54 ± 0.96 (%) and 1032.30 ± 102.76 μM Fe(II), respectively. In conclusion, the silver nanoparticles synthesised by green method can be a potential source for the biomedical applications based on the beneficial properties of the Tualang honey.

The development of an economic and eco-friendly approach of silver nanoparticles synthesis is an important issue due to its wide application, especially in biomedical applications. In present study, an eco-friendly method and size controlling is developed to synthesize silver nanoparticles using Uncaria gambir Roxb. and monoethanolamine (MEA) as bioreducing agent and stabilizing agent, respectively. The green synthesized silver nanoparticles are characterized using UV-Vis spectroscopy, X-ray diffraction (XRD), and transmission electron microscope (TEM). The silver nanoparticles are formed due to reducing of silver ion by catechin in Uncaria gambir Roxb. leaf extract which is visually recognized from the color change from pale yellow to grayish brown. The formation of silver nanoparticles is confirmed by UV-Vis spectroscopy analysis which provides SPR band range of 405–416 nm. The TEM analysis shows that spherical nanoparticles are formed with size range between 6-39 nm. The using of MEA with molar ratio to Ag+ 10/1 can maintain stability and reduce the particle size up to 40%. The result of XRD analysis shows 4 peaks referring to well-crystallized face-centred cubic silver nanoparticles. The prepared silver nanoparticle has exhibited good stability for more than 6 months. The synthesized silver nanoparticles exhibited good antibacterial activity against Staphylococcus aureus and Escherichia coli strain with a diameter of inhibition zone up to 36 mm. The synthesized silver nanoparticles also showed better activity against Escherichia coli than that of Staphylococcus aureus. These results show a good potential of Uncaria gambir Roxb. mediated silver nanoparticles to be developed in biomedical application.

Biological synthesis and characterization of silver nanoparticles with Capparis zeylanica L. leaf extract for potent antimicrobial and anti proliferation efficiency

ABSTRACTBiosynthesis of silver nanoparticles (Ag-NPs) has been achieved by a simple green chemical procedure using flavonoid-rich extract of Froripia subpinnata as a reducing agent and a capping agent. The successful formation of Ag-NPs was confirmed by ultraviolet-visible (UV–vis) spectrometer, field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy, and X-ray diffraction (XRD). FE-SEM and XRD studies showed that the formed silver nanoparticles were spherical in shape with an average particle size of ∼30 nm, crystalline in nature. The effects of Froripia subpinnata extract (FSE) amount, concentration of AgNO3 and temperature were investigated on the synthesis of Ag-NPs. Furthermore, the Ag-NPs exhibited good antibacterial activity against Bacillus subtilis and Staphylococcus aureus (Gram-positive bacteria), Escherichia coli, and Pseudomonas aeruginosa (Gram-negative bacteria). Among the bacteria tested, Bacillus subtilis was found to be most susceptible to the silver nanoparticles.

ABSTRACTBioinspired silver nanoparticles were synthesized using nontoxic, eco-friendly, and novel root extract of Nepeta leucophylla. The reduction of silver nitrate salt into nanoparticles is performed using the root extract, which is rich in polyphenolic and flavonoid contents. The reduction of silver salt by this extract is occurred at several temperatures and the reaction mixture turns brown and displayed representative absorbance spectra of silver nanoparticles. The influence of numerous synthesis parameters such as the concentration of root extract, time, temperature, and reaction pH on the synthesis of silver nanoparticles was also examined. Furthermore, the synthesized silver nanoparticles were characterized by ultraviolet–visible spectroscopy, Fourier transformed infrared spectroscopy, X-ray diffraction, and transmission electron and field emission scanning electron microscopy. The formation of silver nanoparticles was enhanced with time, temperature, and at basic pH. The surface plasmon resonance band characteristics of silver nanoparticles were detected at 410 nm in the ultraviolet–visible absorbance spectra. The infrared spectroscopy results show that the extract contains phenol which is responsible for reduction and proteins may be capping the silver nanoparticles which prevent agglomeration. Transmission electron microscopy revealed that silver nanoparticles were spherical and the sizes matched well with X-ray diffraction and theoretical calculations by Mie theory. Furthermore, the antioxidant potential of the synthesized silver nanoparticles was assessed using 2,2-diphenyl-1-picrylhydrazyl assay and showed considerable antioxidant potential.

This study aim is to know the results of the synthesis of silver nanoparticles from quercetin and Scurrula ferruginea (Roxb. Ex Jack) danser as well as its potential as an antioxidant and anticancer. The solvent used in the maceration extraction method in this research is the polar solvent methanol. Isolation and purification of thick extract compounds from coffee parasite leaves were carried out using liquid vacuum chromatography (CVC) and gravity column chromatography (GCC) methods. Silver (Ag) nanoparticle is made with the stirrer method at a speed of 1500 rpm for 60 minutes at a temperature of 70o C. Silver nanoparticle solution was produced and then characterized using FTIR (Fourier Transform Infra Red) and PSA (Particles Size Analyzer). PSA results analysis using extract coffee parasite size 214 nm particles, whereas using flavonoid isolate quercetin confirmed size 29 nm. FTIR showed that there was a stretching vibration of the OH group at a wave number of 3229.25 cm-1, the C=O function at the wave number 1637.87 cm-1, and the CO functional group at the wave number 1016.31 cm-1. Antioxidant test using the DPPH method was carried out in silver nanoparticle solution using extract Scurrula ferruginea (Roxb. Ex Jack) danser and with quercetin obtained an IC50 value of around 115.4 and 114.9 this result describes as moderate level of antioxidants. Even though the nanoparticle anticancer test was very weak, overall, the synthesis of silver nanoparticles using flavonoid isolates was better than using extracts from coffee parasite leaves.

Phytochemical fabrication and characterization of silver nanoparticles by using Pepper leaf broth

Cancer: a global problem Cancer, a disease initiated by uncontrolled cell division in any part of the body, is a major public health problem globally, includ­ ing in developed countries, as a cause of mor­ bidity and mortality [1]. According to Global Cancer Control, approximately 12.7 million new cancer patients were diagnosed, with 7.6 million deaths, in 2008 and this is pre­ dicted to increase 21.4 million by 2030 [2]. Conventional treatment strategies for cancer include surgery, radiation therapy, chemo­ therapy or combination of these. However, these strategies have several limitations including damaging healthy cells, nonspeci­ ficity, toxicity of anticancer drugs, poor bio­ availability, fast clearance and restrictions in the case of metastasis. According to the highlights published in May 2008 by BCC Research.com, the market value of global can­ cer therapeutics was US$47.3 billion in 2008 and expected to increase US$110.6 billion by 2013 with a compound annual growth rate of 12.6% [3]. Therefore, it is immediately necessary to establish an economically cheaper alterna­ tive treatment strategy for the development of cancer disease rather than the orthodox exist­ ing approaches. In this context, our group has designed and developed green synthe­ sized silver nanoparticles (SNPs) that show multifunctional activities for biomedical applications using a nanomedicinal approach.

Currently, nanobiotechnology is the growing science in the field of medicine employing silver nanoparticles to deliver drugs to target cancer cells and proved to be potential anticancer agents. In this study, silver nanoparticles were synthesized using leaf extract of Leonotis nepetifolia (L). Gas chromatography-mass spectrometry data showed a total of 13 phytochemical constituents identified from ethanolic leaf extract of Leonotis nepetifolia (L). The effect of physicochemical factors such as the reaction time, temperature, concentration of Silver nitrate, concentration of leaf extract and pH in the synthesis of silver nanoparticles. For biosynthesis, the optimal conditions were 1 mM silver nitrate, 0.1 ml of leaf extract at 80° for 90 min. Ultra violet-visible spectroscopy, field emission scanning electron microscopy; high-resolution transmission electron microscopy and various techniques characterized the synthesized AgNPs. The silver nanoparticles obtained had absorbance maxima at 398 nm, were spherical in shape, had an average particle size of 11.32 nm, polydispersity index 0.44, the zeta potential of -23.75.69 mv and were crystalline. A cytotoxicity study was conducted on two human cancer cell lines, pancreatic and ovarian, using sulforhodamine B assay. We had compared the cytotoxicity of biogenic silver nanoparticles with that of synthetic silver nanoparticles. Treatment of pancreatic and ovarian with different concentrations of silver nanoparticles inhibited the cell viability with half maximal inhibitory concentration values of 25.4 μg/ml and 23.9 μg/ml. In contrast, silver nanoparticles inhibited cell viability with half maximal inhibitory concentration values of 48.2 μg/ ml and 42 μg/ml, which were statistically significant (p<0.001), when compared with that of doxorubicin and Camptothecin. Leonotis nepetifolia mediated silver nanoparticles effectively reduced the proliferation of pancreatic and ovarian cancer cell lines than that of synthetic nanoparticles.