Green synthesis of gold nanoparticles from Sophora flavescens extract and their antibacterial effect against some pathogenic bacteria

Aims@#The current study was aimed to evaluate the antibacterial activity of biogenic synthesized golden nanoparticles from Sophora flavescens Aiton roots aqueous extract against multidrug-resistant (MDR) clinical bacterial isolates.@*Methodology and results@#The green synthesis of gold nanoparticles (AuNPs) was accomplished using S. flavescens roots aqueous extract and examined using many accepted techniques. The antibacterial activity of S. flavescens extract and the aqueous AuNPs at concentrations (7% and 9%) ppm were investigated against two clinical MDR bacteria, including Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Pseudomonas aeruginosa). The findings demonstrate inhibitory activity against the selected MDR bacterial isolates for the aqueous extract of S. flavescens and the aqueous AuNPs noted by the significant decrease in the number of bacteria after treatment with highly significant differences (P≤0.01) compared to the untreated control.@*Conclusion, significance and impact of study@#Sophora flavescens root extracts and their biosynthesized AuNPs with antibacterial activity may find broad applications in fighting MDR pathogenic bacteria and therapeutic manufacturing.

Preparation, properties and antibacterial applications of medical nano-metals and their oxides: a review / 生物工程学报

Antibiotics are playing an increasingly important role in clinical antibacterial applications. However, their abuse has also brought toxic and side effects, drug-resistant pathogens, decreased immunity and other problems. New antibacterial schemes in clinic are urgently needed. In recent years, nano-metals and their oxides have attracted wide attention due to their broad-spectrum antibacterial activity. Nano-silver, nano-copper, nano-zinc and their oxides are gradually applied in biomedical field. In this study, the classification and basic properties of nano-metallic materials such as conductivity, superplasticity, catalysis, and antibacterial activities were firstly introduced. Secondly, the common preparation techniques, including physical, chemical and biological methods, were summarized. Subsequently, four main antibacterial mechanisms, such as cell membrane, oxidative stress, DNA destruction and cell respiration reduction, were summarized. Finally, the effect of size, shape, concentration and surface chemical characteristics of nano-metals and their oxides on antibacterial effectiveness and the research status of biological safety such as cytotoxicity, genotoxicity and reproductive toxicity were reviewed. At present, although nano-metals and their oxides have been applied in medical antibacterial, cancer treatment and other clinical fields, some issues such as the development of green preparation technology, the understanding of antibacterial mechanism, the improvement of biosafety, and the expansion of application fields, require further exploration.

Role of biologically synthesised nanoparticles in environmental pollution remediation

Environmental pollution is serious threat for all living organisms. Nanoparticle synthesis using green approach is a non-toxic, easy and energy saving process. Varieties of species have the unique capability to synthesize commercially useful nanoparticles from various metal salt precursors that can help in environmental remediation. The combination of nanotechnology and bioremediation is known as Nanobioremediation. Researchers have shown that biologically nanoparticles shows great potential in reducing environmental pollution from water and soil by adsorption of pollutants and harmful toxic substances from their environment .These green nanoparticles can convert toxic chemicals into less toxic form. Studies also shown that metal nanoparticles also help in removal of harmful bacteria and fungi from environment which can cause diseases in living system. Green synthesised nanoparticles shows very promising results when it comes to environmental remediation they have been used as dye degrader,Oil degrader, photocatalytic agents, biosensors, heavy metals and persidtent organic particulate (POPs) absorbers etc. This review focus on the current status of different types of biologically synthesised nanoparticles in environmental pollution from different species and future challenges associated with environmental remediation.

Exploiting the potential of bio-synthesized silver nanoparticles to enhance the shelf life of Gladiolus

Gladiolus spikes with fully turgid petals need to have a longer shelf life to fetch a higher price as well as display value. To improve the life duration of ornamental flowers, the ability of plants to produce silver nanoparticles (AgNP) was exploited. The ability of plants to produce AgNP when treated with silver nitrate solutions was juxtaposed by using Gladiolus (cut flowers): (i) To find the appropriate concentration of AgNO3 suitable for increasing shelf-life of Gladiolus cut flowers; (ii) To prepare silver nanoparticle from AgNO3; and (iii) To confirm the formation of silver nanoparticle using UV-vis spectrophotometry. Two different reductants (dehydrogenases present at the surface of the plant cells and sucrose) demonstrated the reduction of Ag+ to generate AgNPs. DLS (Dynamic Light Scattering) study revealed the presence of NPs in the AgNO3 salt solution incubated with Gladiolus cut flowers. The DLS data also suggested that the size of AgNPs decreased with increasing concentration of AgNO3. In the present study, along with silver nitrate, sucrose was also used. The shelf life and display value of the cut Gladiolus can be increased and optimized by incubating it in sucrose solution in combination with AgNO3.

Green synthesis of gold nanaoparticles using Delphinium Chitralense tuber extracts, their characterization and enzyme inhibitory potential / Síntese verde de nanaopartículas de ouro utilizando extratos de tubérculos Delphinium chitralense, sua caracterização e potencial inibitório enzimático

Greeen synthesis has been introduced as an alternative to chemical synthesis due to the serious consequences. Metal nanoparticles synthesized through green approach have different pharmaceutical, medical and agricultural applications. The present study followed a green and simple route for the preparation of potentially bioactive gold nanoparticles (Au NPs). Au NPs were prepared via green synthesis approach using crude basic alkaloidal portion of the tuber of Delphinium chitralense. The green synthesized Au NPs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) fourier transform infrared (FTIR), and UV-Visible spectrophotometer. Morphological analysis shows that Au NPs have cubic geometry with different sizes. UV-Vis spectroscopic analysis confirmed the synthesis of Au NPs while XRD proved their pure crystalline phase. The Au NPs showed promising dose dependent inhibition of both AChE and BChE as compared to the crude as well as standard drug.

A síntese verde foi introduzida como uma alternativa à síntese química devido às graves consequências. As nanopartículas metálicas sintetizadas através da abordagem verde têm diferentes aplicações farmacêuticas, médicas e agrícolas. O presente estudo seguiu uma rota verde e simples para a preparação de nanopartículas de ouro potencialmente bioativas (Au NPs). As NPs de Au foram preparadas via abordagem de síntese verde usando a porção alcaloide básica bruta do tubérculo de Delphinium chitralense. As NPs de Au sintetizadas verdes foram caracterizadas por microscopia eletrônica de transmissão (TEM), microscopia eletrônica de varredura (MEV), difração de raios X (DRX), infravermelho com transformada de Fourier (FTIR) e espectrofotômetro UV-Visível. A análise morfológica mostra que as NPs de Au possuem geometria cúbica com tamanhos diferentes. A análise espectroscópica UV-Vis confirmou a síntese de Au NPs enquanto a XRD provou sua fase cristalina pura. O Au NPs mostrou inibição dependente da dose promissora de AChE e BChE em comparação com a droga bruta e padrão.

Zinc oxide nanoparticles synthesized using Hyssopus Officinalis L. Extract Induced oxidative stress and changes the expression of key genes involved in inflammatory and antioxidant Systems

BACKGROUND: Recent advances in the synthesis of bioactive nanoparticles resulted in the discovery and introduction of new bioactive nanoparticles to the pharmaceutical industry. In this regard, this research is aimed to synthesize the zinc oxide nanoparticles (ZnO-NPs) using Hyssopus officinalis L. extract and to evaluate the safety of nanoparticles using Balb/C mice. METHODS: Forty male mice were divided into four groups and received 0, 50, 100, and 200 mg/kg of ZnO-NPs for thirty days. At the end of the experiment, blood sugar, creatinine, aspartate aminotransferase (A.S.T.), and alanine aminotransferase (A.L.T.) were determined. Furthermore, histopathological and oxidative stress biomarker analyses in liver and kidney tissues were performed. The changes in the major inflammatory- and antioxidant-related genes were determined. RESULTS: The results showed that blood sugar and creatinine reduced significantly (P < 0.05) when 50, 100, and 200 mg/kg ZnO-NPs were supplemented to the diet. The serum ALT and AST and lipid peroxidation in the liver and kidney tissues were increased significantly (p < 0.05) when 50, 100, and 200 mg/kg ZnO-NPs were supplemented to the diet. Supplementation of ZnO-NPs suppressed the expression of antioxidant-related genes (SOD and CAT) and up-regulated the inflammatory biomarkers (iNOS and TNF- α). The concentration of 200 mg/Kg nanoparticles indicated cellular degeneration and necrosis in the liver and kidney tissues. CONCLUSIONS: Overall, it can be concluded that supplementation of ZnO-NPs synthesized using Hyssopus Officinalis L. extract in this study at 50 mg/kg or higher concentrations might be toxic to the mice.

In vitro anti-inflammatory, anti-arthritic and anti- proliferative activity of green synthesized silver nanoparticles - Phoenix dactylifera (Rothan dates)

Abstract Traditionally dates is consumed as a rich source of iron supplement and the current research discuss the synthesis of silver nanoparticles (AgNPs) using methanolic seed extract of Rothan date and its application over in vitro anti-arthritic, anti-inflammatory and antiproliferative activity against lung cancer cell line (A549). FTIR result of synthesised AgNPs reveals the presence of functional group OH as capping agent. XRD pattern confirms the crystalline nature of the AgNPs with peaks at 38º, 44º, 64º and 81º, indexed by (111), (200), (220) and (222) in the 2θ range of 10-90, indicating the face centered cubic (fcc) structure of metallic Ag. HR- TEM results confirm the morphology of AgNPs as almost spherical with high surface areas and average size of 42 ± 9nm. EDX spectra confirmed that Ag is only the major element present and the Dynamic light scattering (DLS) assisted that the Z-average size was 203nm and 1.0 of PdI value. Zeta potential showed − 26.5mv with a single peak. The results of the biological activities of AgNPs exhibited dose dependent activity with 68.44% for arthritic, antiinflammatory with 63.32% inhibition and anti-proliferative activity illustrated IC50 value of 59.66 µg/mL expressing the potential of AgNPs to combat cancer

Green synthesis of gold nanaoparticles using Delphinium Chitralense tuber extracts, their characterization and enzyme inhibitory potential

Abstract Green synthesis has been introduced as an alternative to chemical synthesis due to the serious consequences. Metal nanoparticles synthesized through green approach have different pharmaceutical, medical and agricultural applications. The present study followed a green and simple route for the preparation of potentially bioactive gold nanoparticles (Au NPs). Au NPs were prepared via green synthesis approach using crude basic alkaloidal portion of the tuber of Delphinium chitralense. The green synthesized Au NPs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) fourier transform infrared (FTIR), and UV-Visible spectrophotometer. Morphological analysis shows that Au NPs have cubic geometry with different sizes. UV-Vis spectroscopic analysis confirmed the synthesis of Au NPs while XRD proved their pure crystalline phase. The Au NPs showed promising dose dependent inhibition of both AChE and BChE as compared to the crude as well as standard drug.

Resumo A síntese verde foi introduzida como uma alternativa à síntese química devido às graves consequências. As nanopartículas metálicas sintetizadas através da abordagem verde têm diferentes aplicações farmacêuticas, médicas e agrícolas. O presente estudo seguiu uma rota verde e simples para a preparação de nanopartículas de ouro potencialmente bioativas (Au NPs). As NPs de Au foram preparadas via abordagem de síntese verde usando a porção alcaloide básica bruta do tubérculo de Delphinium chitralense. As NPs de Au sintetizadas verdes foram caracterizadas por microscopia eletrônica de transmissão (TEM), microscopia eletrônica de varredura (MEV), difração de raios X (DRX), infravermelho com transformada de Fourier (FTIR) e espectrofotômetro UV-Visível. A análise morfológica mostra que as NPs de Au possuem geometria cúbica com tamanhos diferentes. A análise espectroscópica UV-Vis confirmou a síntese de Au NPs enquanto a XRD provou sua fase cristalina pura. O Au NPs mostrou inibição dependente da dose promissora de AChE e BChE em comparação com a droga bruta e padrão.

Synthesis of Gold Nanoparticles using Bioreductants from the Aqueous Leaves Extract of Dillenia philippinensis Rolfe. (Katmon)

Background and Objectives@#Endemic plants are integral part of the ecosystem that provide innumerable benefits. Thus, emerging studies and applications using these endemic plants continue to increase globally. In this study, the preparation of gold nanoparticles (AuNPs) has been carried out by using the aqueous leaves extract of Dillenia philippinensis Rolfe. (Katmon) as the bioreductants. @*Methodology@#After the synthesis of AuNPs, the process was further subjected to optimization to assure the production of AuNPs with the best parameters. Synthesized and optimized AuNPs were characterized using FTIR, XRD, DLS, Zeta Potential, and TEM. @*Results@#Optimization results that provide the desired properties for AuNPs were a volume ratio of 1:2 (HAuCl₄: leaves extract), no significant difference (p>0.05) with the sequence of addition and reaction time, and acidic pH. The synthesized AuNPs' particles were found to contain hydroxyl and amine groups, had broad, amorphous, and spherical particles that have a mean diameter of 60.6nm, a PDI of 0.563, and a repulsion force of -13.720mV. The optimized and characterized AuNPs were then further used as a colorimetric sensing material, showing the potential applicability of AuNPs in the heavy metal analysis.@*Conclusion@#Gold nanoparticles were able to be synthesized with the use of bioreductants that are present in the aqueous leaves extract of Katmon. This concludes that endemic plants in the Philippines can be used for the synthesis of AuNPs and can be applied in the field of phytonanotechnology and other applied sciences.

Green Synthesized Silver Nanostructure Using Rhus coriaria Fruit Extract Inhibits the Growth of Malignant MCF-7 Cell Line

Abstract Rhus coriaria, popularly known as sumac, has been used as a spice powder in the Middle East for centuries. It contains a broad range of naturally occurring compounds such as flavonoids, proteins, anthocyanins and volatile oils. It showed a putative importance in treatment of different disorders including cancers. In the current study, R. coriaria fruit extract was used for green synthesis of silver nanostructures (Ag-NSs) and their anticancer activity was tested against human breast cancer cells (MCF-7). The aqueous fruit extract was prepared. The synthesis of Ag-NSs under different conditions was optimized. The optimal reaction medium comprised 1:2 concentration of fruit extract and 3 mM concentration of silver nitrate solution. The green-synthesized Ag-NSs were confirmed by using UV-Visible spectroscopy at a range 300-700 nm, transmission electron microscopy (TEM), X-ray diffraction (XRD) and zeta potential measurements. The anti-proliferative activity of Ag-NSs was confirmed with inhibitory activity on MCF-7 cell line growth. The results showed that the IC50 values at 24 and 48h were 14.27 and 13.4 μg/ml, respectively. In conclusion the results of this study provide a simple, rapid, non-toxic and eco-friendly protocol for green-synthesis of Ag-NSs, which could be used as an alternative and interesting approach for safe and simple synthesis of Ag nanoparticles for biomedical uses.

Synthesis and Biological Properties of Silver Chloride Nanoparticles Using Cell-free Extracts of Aeromonas ‎hydrophila and Antibacterial Activity against Drug-Resistant Bacteria

Abstract Microorganisms have been studied as potential biological factories for the synthesis of silver nanoparticles. In the present study, the cell-free extract of Aeromonas ‎hydrophila was used to synthesize silver nanoparticles because the extract has a dual role in reducing and stabilizing silver nanoparticles. In this study, silver nanoparticles were synthesized using Aeromonas hydrophila. Synthetic nanoparticles were examined using ultraviolet-visible spectroscopy, X-ray diffraction, Fourier transform infrared (FT-IR), transmission electron microscopy (TEM) and X-ray diffraction (EDX) spectroscopy. In this study, antimicrobial properties of Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa and anti-cancer properties (MCF-7, HepG-2) of silver nanoparticles were investigated. The synthesis of silver nanoparticles was confirmed by ultraviolet-visible spectroscopy and X-ray diffraction. TEM images detected the spherical shape of nanoparticles of various sizes in the range of 1-20 nm. FT-IR analysis demonstrated that enzyme, protein and carbohydrate compounds can be proven as stabilizing agents on the surface of silver nanoparticles. The resulting nanoparticles had strong antibacterial activity against drug-resistant bacteria. Silver chloride nanoparticles were also toxic to MCF-7 and HepG-2 cancer cells. The green synthesis method is cost-effective, environmentally friendly and an easy alternative to conventional silver nanoparticle synthesis methods.

Simarouba Glauca Bark Extract Mediated Synthesis And Characterisation Of Iron Oxide And Silver Nanoparticles And Their Antibacterial, Cytotoxic And Photocatalytic Activity

Objective: The objective of the present study is the synthesis of iron oxide and silver nanoparticles using Simarouba glauca aqueous bark extract, characterization of the synthesized nanoparticles and evaluation of their antimicrobial, photocatalytic activity and cytotoxicity. Methods: The iron oxide and silver nanoparticles were synthesized using Simarouba glauca aqueous bark extract and crystal structures of the nanoparticles were determined by UV-Visible spectroscopy, Transmission Electron Microscopy, Scanning Electron Microscopy, X-ray Diffraction and Fourier Transform Infrared Spectroscopy. The in vitro cytotoxicity of the silver nanoparticles was evaluated using Dalton’s lymphoma ascites cells. The antibacterial assay of the silver nanoparticles was conducted using agar well diffusion method. Results: The UV-Visible spectrum of iron oxide nanoparticle showed an absorption maximum at 280 nm and silver nanoparticles showed an absorption maximum at 436 nm. This is XRD pattern of iron oxide nanoparticles exhibited a characteristic peak at 26.85 is of maghemite the corresponding miller indices is (211) and the synthesized iron oxide nanoparticles are amorphous in nature. TEM image reveals the size of the synthesized iron oxide nanoparticles in the range of 26-30 nm and the size of silver nanoparticles is in the range of 120-140 nm. Green synthesized iron nanoparticles using Simarouba glauca bark extract effectively degraded methylene blue dye. Conclusion: This study showed that the synthesized iron oxide and silver nanoparticles using Simarouba glauca aqueous bark extract exhibited pronounced antibacterial, anticancer and photocatalytic activity and can be used in the textile industry and also as an external antiseptic in prevention and treatment of bacterial infections.

Green synthesis, characterization and antimicrobial evaluation of silver nanoparticles for an intracanal dressing

Abstract Green chemistry has been applied in different areas due to the growing demands for renewable processes and one of them is nanotechnology. The aim of this study was to characterize a formulation containing silver nanoparticles (AgNPs) produced by a green synthesis and to evaluate its antimicrobial activity. The formulation will be used as an intracanal dressing exploiting the AgNPs' antimicrobial properties, which are crucial to prevent infections and bacterial reinfections that can compromise endodontic treatments. In the green synthesis, silver nitrate was employed as the precursor salt, maltose as a reducing agent, and gelatin as a stabilizing agent. The formulation was prepared mixing 50 % of a liquid containing the AgNPs and 50 % of hydroxyethylcellulose gel at 1.5 % with proper evaluation of the process inherent parameters. Techniques such as molecular absorption spectrometry and dynamic light scattering were used in characterization step. The antimicrobial activity of the AgNPs against Escherichia coli ATCC 25922, Enterococcus faecalis NCTC 775, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923 and Streptococcus mutans ATCC 25175 was verified according to National Comittee for Clinical Laboratory Standards (NCCLS) by determining minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). The obtained results indicated the formulation containing AgNPs produced by a green synthesis was properly characterized by the selected techniques. Furthermore, the formulation assessment proved that it is suitable for the proposal as well as it has potential to be used as an intracanal dressing since presented antimicrobial activity against all bacterial strains evaluated.

Resumo A química verde tem sido aplicada em diferentes áreas devido à crescente demanda por processos renováveis e uma delas é a nanotecnologia. O objetivo deste estudo foi caracterizar uma formulação contendo nanopartículas de prata (AgNPs) produzidas por meio de síntese verde e avaliar sua atividade antimicrobiana. A formulação será usada como curativo intracanal explorando as propriedades antimicrobianas das AgNPs que são cruciais para prevenir infecções e reinfecções bacterianas que podem comprometer os tratamentos endodônticos. Na síntese verde, nitrato de prata foi empregado como sal precursor, maltose como agente redutor e gelatina como agente estabilizador. A formulação foi preparada misturando-se 50% do líquido contendo as AgNPs e 50% de gel de hidroxietilcelulose a 1,5% com avaliação adequada dos parâmetros inerentes ao processo. Técnicas como espectrometria de absorção molecular e espalhamento dinâmico de luz foram usadas na etapa de caracterização. A atividade antimicrobiana das AgNPs contra Escherichia coli ATCC 25922, Enterococcus faecalis NCTC 775, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923 e Streptococcus mutans ATCC 25175 foi verificada de acordo com o National Comittee for Clinical Laboratory Standards (NCCLS), determinando-se a concentração inibitória mínima (MIC) e a concentração bactericida mínima (MBC). Os resultados obtidos indicaram que a formulação contendo AgNPs produzidas por meio de síntese verde foi devidamente caracterizada pelas técnicas selecionadas. Além disso, a avaliação da formulação provou que ela é adequada para a proposta, bem como tem potencial para ser utilizada como curativo intracanal já que apresentou atividade antimicrobiana contra todas as cepas bacterianas avaliadas.

Antibacterial Activity of White Pepper Oleoresin Mediated Silver Nanoparticles against Oral Pathogens.

Plant mediated biological synthesis of silver nanoparticles is gaining importance due to its eco friendliness and simplicity. Different types of nanoparticles such as metal, metal oxide, metal sulphide and polymer nanoparticles are used in different types of applications in the fields of electronics, communications, electrical, mechanical, medical, dental etc. Aim of the present study was to evaluate the antibacterial activity of white pepper oleoresin mediated silver nanoparticles against oral pathogens. MethodsIn the present investigation, white pepper mediated synthesis of silver nanoparticles was carried out by the addition of silver nitrate with prepared white pepper oleoresin solution. White pepper oleoresin mediated silver nanoparticles were initially confirmed by colour changes and confirmed by UV- Visible spectroscopy. Anti-bacterial activity of the synthesised silver nanoparticles was carried out using agar well diffusion method. Different concentrations of silver nanoparticles were tested against different oral pathogens such as Staphylococcus aureus, Streptococcus mutans and Pseudomonas sp. ResultsThe solution containing white pepper oleoresin and silver nitrate solution showed a brown colour confirming the formation silver nanoparticles and peak at 350 nm revealed the silver nanoparticles surface plasmon resonance. The white pepper oleoresin mediated silver nanoparticles showed good antibacterial activity against all tested microorganisms and the maximum activity was found with Pseudomonas spp. followed by Staphylococcus aureus, and Streptococcus mutans. ConclusionsGreen synthesis of silver nanoparticles using white pepper oleoresin was of low cost and was convenient to carry out. Hence, white pepper oleoresin mediated silver nanoparticles may be used for the control of oral pathogens.

High antibacterial properties of green synthesized gold nanoparticles using Uncaria gambir Roxb. leaf extract and triethanolamine

The development of antibacterial agents is increasingly gaining much attention due to the expansion activity ofmulti-drug resistant bacteria in causing many diseases. Metallic nanoparticles especially gold nanoparticles in thefield of nanotechnology is one of the new and significant materials to be developed as antibacterial agents. Goldnanoparticles have been successfully synthesized using Uncaria gambir Roxb. leaf extract as a bioreducing agent andtriethanolamine as a capping agent, through reduction of Au+3 by flavonoid compound in the leaf extract. The effect oftriethanolamine and hydrogen tetrachloroaurate (III) acid concentration on the stability and size of nanoparticles wasstudied. The presence of triethanolamine 1% as a capping agent successfully maintained the stability of colloidal goldnanoparticles with a concentration of hydrogen tetrachloroaurate (III) acid at 100 ppm. X-Ray Diffraction analysisshowed peak patterns corresponding to the metallic gold standard with a crystallite size of 32.52 nm. TransmissionElectron Microscope analysis showed that particles were spherical, hexagonal, and triangular, where the smallestparticle size was 7 nm. Synthesized gold nanoparticles showed great antibacterial activity against E. coli and S. aureus.The stability and antibacterial activity of synthesized gold nanoparticles showed good potential to be developed inbiomedical applications

Antioxidant and antibacterial activity of silver nanoparticles synthesized by Cestrum nocturnum

Background: Silver nanoparticles are toxic to bacteria and have widespread application in differentresearch areas.Objective: The aim of this study was to synthesize silver nanoparticles using an aqueous leaf extract ofCestrum nocturnum and to test its antioxidant and antibacterial activities.Materials and methods: The silver nanoparticles were synthesized by addition of 20 ml extract (8% w/v)with 180 ml silver nitrate solution (1 mM). The synthesis of silver nanoparticles was confirmed byUVeVis spectrophotometer. The silver nanoparticles were characterized by X-ray diffractometer,Transmission Electron Microscope, Scanning Electron Microscope and Fourier Transform Infra-Redspectroscopy. The antioxidant property of silver nanoparticles was analyzed by the 2, 2-diphenyl-1-picrylhydrazyl, hydrogen peroxide, hydroxyl radical and superoxide radical scavenging methods. Thebacteriostatic and bactericidal activity of silver nanoparticles against Escherichia coli, Enterococcus faecalis, and Salmonella typhi was determined using bacterial growth inhibition method. The antibacterialsensitivity and Minimum Inhibitory Concentration (MIC) of silver nanoparticles was determined againstthe bacteria.Results: The results confirmed that the silver nanoparticles synthesized by C. nocturnum extract werecrystalline in nature, average particle size was 20 nm and were mostly spherical in shape. The antioxidant methods confirmed that the silver nanoparticles have more antioxidant activity as compared tovitamin C. The silver nanoparticles have strong antibacterial (maximum Vibrio cholerae and minimumE. faecalis) activity. The MIC value of silver nanoparticles was 16 mg/ml (Citrobacter), 4 mg/ml (E. faecalis),16 mg/ml (S. typhi), 8 mg/ml (E. coli), 8 mg/ml (Proteus vulgaris), and 16 mg/ml (V. cholerae).Conclusion: Green synthesized silver nanoparticles have strong antioxidant and antibacterial activity dueto the presence of bioactive molecules on the surface of silver nanoparticles.© 2018 Transdisciplinary University, Bangalore and World Ayurveda Foundation. Publishing Services byElsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Characteristics of selenium nanoparticles synthesized by cell-free supernatant Cupriavidus sp. SHE / 生物工程学报

In recent years, selenium nanoparticles (SeNPs) have been widely used in many fields such as nanotechnology, biomedicine and environmental remediation due to their good electrical conductivity, photothermal properties and anticancer properties. In this study, the cell-free supernatant, whole cell and the cell-free extracts of the strain Cupriavidus sp. SHE were used to synthesize SeNPs, and several methods were applied to analyze the crystal structure and surface functional groups of the nanoparticles. Finally, Pseudomonas sp. PI1 (G⁺) and Escherichia coli BL21 (G⁻) were selected to investigate the antibacterial properties of SeNPs. Cell-free supernatant, whole cell and cell-free extracts of the strain could synthesize SeNPs. As for the cell-free supernatant, selenite concentration of 5 mmol/L and pH=7 were favorable for the synthesis of SeNPs. TEM images show that the average size of nanospheres synthesized by the supernatant was 196 nm. XRD analysis indicates the hexagonal crystals structure of SeNPs. FTIR and SDS-PAGE confirmed the proteins bound to the surfaces of SeNPs. SeNPs synthesized by cell-free supernatant showed no antimicrobial activities against Pseudomonas sp. PI1 and Escherichia coli BL21 (DE3). These results suggest that proteins played an important role in biotransformation of SeNPs in an eco-friendly process, and SeNPs synthesized in this study were non-toxic and biologically compatible, which might be applied in other fields in the future.

Green synthesis of gold nanoparticles from waste macadamia nut shells and their antimicrobial activity against Escherichia coli and Staphylococcus epidermis

Background: The study for the first time demonstrates an eco-friendly and room temperature procedure for biosynthesizing gold (Au) nanoparticles from waste Macadamia nut shells. Currently Australia contributes around 40% to the global market and generates around AUS $150 million of export revenue. However, a consequence of large nut production is the generation of large quantities of waste nut shells. The green chemistry-based method is clean, nontoxic and eco-friendly. The method presented in this study produced a variety of Au nanoparticle sizes and shapes.Methods: The straightforward green chemistry-based technique used waste Macadamia nut shells to generate Au nanoparticles, which were subsequently studied using several advanced characterization techniques. Furthermore, the Kirby-Bauer sensitivity method was used to evaluate the antibacterial properties of the extracts and synthesized gold nanoparticles.Results: Advanced characterisation revealed the Au nanoparticles were crystalline, ranged in size from 50nm up to 2µm, and had spherical, triangular and hexagonal morphology. The gram-negative bacteria Escherichia coli produced a maximum inhibition zone of 11mm, while Staphylococcus epidermidis produced a maximum inhibition zone of 9mm.Conclusions: The study has shown that waste Macadamia nut shell extracts have no antibacterial activity, but the synthesised Au nanoparticles did display antibacterial activity to both Escherichia coli and Staphylococcus epidermidis. Thus, the present work has demonstrated a waste valorisation strategy that can be used to produce high-value Au nanoparticles with antimicrobial properties for use in future pharmaceuticals.

Characterization and Cytotoxic Evaluation of Silver and Gold Nanoparticles Produced with Aqueous Extract of Lavandula dentata L. in Relation to K-562 Cell Line

Abstract Metallic nanoparticles have great potential as a chemotherapeutic agent. The aim of this study was to develop and characterize silver and gold nanoparticles using a simple method, as well as evaluating the potential cytotoxic activity in relation to the K-562 cell line. For the synthesis, a solution containing the metallic ions was subjected to magnetic stirring with the aqueous extract of Lavandula dentata L. and a change of colour was observed. With the data obtained from the analyses we concluded that the nanoparticles were successfully obtained by a simple and green method using the aqueous extract of L. dentata. The obtained nanoparticles presented a reduced size, a low level of polydispersion, and a homogenous spherical shape. The nanoparticles presented intense and characteristic diffraction peaks, which could be correlated to the planes of the centred cubic structure of the silver and gold. The two formulations presented predominantly crystalline characteristics. The infrared analysis suggested that the amides and alcohols present in the samples may have been responsible for the reduction and limitation of the size and dispersion of the silver and gold nanoparticles. The cytotoxic assay showed that the nanoparticles demonstrated great potential to reduce the cell viability of the K-562 cell line, especially the gold nanoparticles.

Antiplasmodial activity of silver nanoparticles: A novel green synthesis approach

Objective: To synthesize silver nanoparticles using silver nitrate by a green technique which involves different compositions of aqueous leaf extracts of Azadirachta indica (neem) and Ocimum sanctum (tulsi). Methods: Their shape and size were determined using transmission electron microscopy and UV-visible spectroscopy. Their antiplasmodial activity was studied using the malarial parasite strain (Plasmodium falciparum, 3D7). The parasite strain (3D7) was collected and revived in vitro using Trager and Jensen method in RPMI 1640 medium for 7-8 cycles. Half maximal effective concentration values were calculated by nonlinear regression analysis. Results: Transmission electron microscopy results confirmed the formation of silver nanoparticles with size ranging from 4.74-39.32 nm and their size differs by varying the concentrations from 20% to 100% of neem extract in neem and tulsi extracts. It was observed that samples B and C showed half maximum effective concentration of about 0.3 μ M. Conclusions: It can be easily established that the aqueous leaf extracts of neem and tulsi in combination can be a good source for synthesis of silver nanoparticles with small size possessing appreciable antiplasmodial activity.