Keywords : Green synthesis

Green Synthesis and Characterization of Silver Nanoparticles using Cassia auriculata Leaves Extract and Its Efficacy as A Potential Antibacterial and Cytotoxic Effect

S. P. Vinay; N. Chandrasekhar

Advanced Materials Letters, 2019, Volume 10, Issue 11, Pages 844-849
DOI: 10.5185/amlett.2019.0046

Silver nanoparticles (Ag NPs) were prepared using Cassia auriculata leaves extract as a reducing agent via green synthesis method. From the PXRD, UV-Visible, FTIR, studies the synthesized NPs were characterized. The morphologies of the prepared NPs were studied by SEM and TEM analysis. The synthesized NPs were tested for antibacterial and anticancer studies. The PXRD data indicated that the synthesized nanoparticles belong to cubic phase structure. Presence of strong silver peaks was confirmed by EDAX studies. The SEM and TEM data revealed that spherical like structure were obtained. Antibacterial (MIC from 75 to 150 μl) activities were noticed for green synthesized Ag NPs. Furthermore, in vitro studies revealed dose-dependent cytotoxic effects of Ag NPs treated PC-3 cell line. This is the first report on the green synthesis of Ag NPs using leaves extract of C. auriculata. Results of present study could contribute to synthesize new and cost-effective drugs from C. auriculata by using green approach. Copyright © VBRI Press.

Silver nanoparticles mediated by extract of Guar plant (Cyamopsis tetragonoloba), and evaluation of their photocatalytic and antibacterial properties

Elias E. Elemike; Saiyed Tanzim; Anthony C. Ekennia; Damian C. Onwudiwe

Advanced Materials Letters, 2019, Volume 10, Issue 4, Pages 284-293
DOI: 10.5185/amlett.2018.2198

The green synthesis of silver nanoparticles using Cyamopsis tetragonoloba plant extract and their photocatalytic and antibacterial properties is reported. Three precursor concentrations of 1 mM, 2 mM and 5 mM were used, and at two different ratios of 1:5 and 1:10 plant extract to the precursor. The formation of the nanoparticles was followed by the periodic study of surface plasmon resonance using the UV-visible spectroscopy, which revealed the formation of nanoparticles with regular bands after 45 min. of reaction. Fourier transform infrared spectroscopy was used to study the functional groups present in the plant biomolecules which aided the reduction and stabilization of the nanoparticles. Transmission electron microscopy analysis and X-ray diffraction pattern showed the particle sizes and crystalline structures, while the zeta potential values indicated the stability of the nanoparticles. The 5 mM concentration gave the largest particle sizes of about 12.90 nm and the most stable particles. The photocatalytic properties of the particles studied using Methyl red showed a low efficiency of 17.85% degradation achieved under 2 h. The antibacterial potency of the nanoparticles was screened against some gram-negative and gram-positive bacteria. The results showed that the nanoparticles have good antibacterial activities.

Optical properties of TiO2@C nanocomposites: Synthesized by green synthesis technique

Srikanta Karmakar; Subrata Biswas; Pathik Kumbhakar; Tapan Ganguly

Advanced Materials Letters, 2017, Volume 8, Issue 4, Pages 449-457
DOI: 10.5185/amlett.2017.1421

In this work, we have reported an eco-friendly and cost-effective technique of synthesis of TiO2@Carbon nanocomposites (TCNs) material by a facile solvothermal treatment of banana (Musa balbisiana) bract extract. Yellow-green photoluminescence (PL) feature and efficient catalytic activities of green synthesized TCNs have been demonstrated. X-ray diffraction (XRD) data has revealed the simultaneous presence of rutile and anatase phases of TiO2 in the synthesized TCNs. The presence of amorphous carbon and TiO2 is also confirmed by Raman spectroscopy. The light emission characteristics of TCNs are studied by PL emission spectroscopy which has confirmed the presence of defect levels caused by oxygen vacancies and surface hydroxyl groups localized within the band-gap. The photocatalytic performance of the synthesized material has been systematically evaluated by observing the degradation of Methylene Blue (MB) dye under the incidence of ultraviolet-visible (UV-Vis)/visible light irradiation and manifested a superior UV-Vis light photo-catalytic activity far over the commercial TiO2 powder (CTP) under the same experimental conditions. A relatively higher electrochemical performance and 52 times larger cathodic current density is obtained in TCNs in compared to that of CTP. TCNs exhibit extremely high hydrogen evolution reaction catalytic activity with very small onset over potential.

Silver Nanoparticles Prepared From Herbal Extract Of Terminalia Bellerica For Selective Detection Of Mercury Ions

Alagan Jeevika; Raj Sarika; Dhesingh Ravi Shankaran

Advanced Materials Letters, 2016, Volume 7, Issue 12, Pages 1021-1028
DOI: 10.5185/amlett.2016.6426

In this work, we have investigated the uses of herbal extract of Terminalia bellerica (T.bellerica) as an efficient reducing as well as capping agent for reliable green synthesis of silver nanoparticles (AgNPs) at room temperature. HR-TEM results of AgNPs confirmed that, the nanoparticles are spherical in shape with an average diameter of ~30 ± 6 nm.  XRD shows that, AgNPs exhibits the face centered cubic (FCC) structure. AgNPs utilized as a nanosensor probe for detection of mercury ions (Hg 2+ ). AgNPs showed a color change from brownish yellow to colorless on exposed to Hg 2+ due to the redox reaction of mercury and silver. This sensor probe showed a lower limit of detection of 0.3 ± 0.005 µM. Selectivity of the sensor has been evaluated towards other environmentally heavy metal ions and found that, this sensor is highly selective to Hg 2+ . AgNPs loaded poly (vinylalcohol) (PVA) films and nanofibers were fabricated by solvent casting and electrospinning methods, respectively. AgNPs loaded PVA films and nanofibers were tested for anti-bacterial studies against E. coli and B. subtils. The results indicate that the green synthesized AgNPs possess high microbial activity towards E.coli. These AgNPs based functional materials have great potential for application in sensors, anti-microbial coatings, wound dressing and smart textiles.

Phytochemical Fabrication And Characterization Of Silver/ Silver Chloride Nanoparticles Using Albizia Julibrissin Flowers Extract

Akl M. Awwad

Advanced Materials Letters, 2015, Volume 6, Issue 8, Pages 726-730
DOI: 10.5185/amlett.2015.5816

Silver/ silver chloride (Ag/AgCl-NPs) nanoparticles were synthesized by a simple procedure using Albizia julibrissin flowers extract. The flowers of Albizia julibrissin extract acts a reducing, chlorinated and capping agent in the formation of Ag/AgCl-NPs. UV-visible spectroscopy was used to monitor the quantitative formation of silver/ silver chloride nanoparticles. For complete conversion of silver ions to silver/ silver chloride nanoparticles, time of reaction is less than 5 min at temperature 80 o C and 24h in dark conditions at room temperature. The synthesized Ag/AgCl-NPs nanoparticles were characterized with X-ray diffraction (XRD), UV-vis Spectroscopy, scanning electron microscopy (SEM) and Fourier transforms infrared spectroscopy (FT-IR). UV-visible absorption studies revealed surface plasmon resonance (SPR) peak around 410-430 nm, confirming the presence of Ag/AgCl nanoparticles. The average particle size ranged from 5-20 nm. The particle size could be controlled by changing the flowers extract, silver ion concentration and temperature. FT-IR spectra of flowers extract before and after the synthesis of silver/ silver chloride nanoparticles were determined to allow identification of possible functional groups responsible for the reduction of silver ions to silver/silver chloride nanoparticles.

Noval Approach For Synthesis Sulfur (S-NPs) Nanoparticles Using Albizia Julibrissin Fruits Extract

Akl M. Awwad; Nidá M. Salem; Amany O. Abdeen

Advanced Materials Letters, 2015, Volume 6, Issue 5, Pages 432-435
DOI: 10.5185/amlett.2015.5792

Sulfur nanoparticles have been successfully prepared from sodium thiosulfate in the presence of Albizia julibrissin fruits extract at room temperature. The resulting sulfur nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). XRD characterizes the final product as highly crystalline sulfur, exhibited high purity, spherical shape with average particle size of about 20 nm, and particle size distribution in range 10 nm to 100 nm. The particle size of nanoparticles could be controlled by tuning the amount of Albizia julibrissin fruits extract. FT-IR analysis of S-NPs indicated a new chemistry linkage on the surface of sulfur nanoparticles. This suggests that Albizia julibrissin fruits extract can bind to sulfur nanoparticles through carbonyl of the amino acid residues in the protein of the extracts, therefore acting as stabilizer and dispersing agent for synthesized sulfur nanoparticles. This research provides a greener and more environment-friendly synthetic method for the production of sulfur nanoparticles for antibacterial and antifungal activities.

Green Synthesis Of Silver Nanoparticles Using Asiatic Pennywort And Bryophyllum Leaves Extract And Their Antimicrobial Activity

Dulen Saikia; Pradip K. Gogoi; Pallabi Phukan; Nilave Bhuyan; Sangeeta Borchetia; Jibon Saikia

Advanced Materials Letters, 2015, Volume 6, Issue 3, Pages 260-264
DOI: 10.5185/amlett.2015.5655

Silver nanoparticles of average sizes ~18-21 nm in diameter were prepared by a green approach via chemical reduction of silver nitrate (AgNO3) using Asiatic Pennywort and Bryophyllum leaf extracts as reducing and capping agents. The bio-reduced silver nanoparticles were characterized by UV-Vis spectroscopic, XRD and TEM techniques. The characteristic surface plasmon band of colloidal solutions of AgNPs synthesized from Asiatic Pennywort and Bryophyllum leaf extracts were found at 445 nm and 405 nm respectively. The results of XRD and SAED pattern showed that the biosynthesized AgNPs have a crystalline structure with cubic phase (fcc). The antimicrobial activities of the as synthesized AgNPs were investigated against gram negative bacteria Pseudomonas Fluorescens and gram positive bacteria Staphylococcus Epidermidis. It was observed that silver nanoparticles obtained from Asiatic Pennywort was more effective on gram positive bacteria Staphylococcus Epidermidis while AgNPs obtained from Bryophyllum was more effective on gram negative bacteria Pseudomonas Fluorescens indicating size dependent activity of AgNPs.

Green Syntheis Of Silver Nanoparticles And Its Activity On SiHa Cervical Cancer Cell Line

Anal K. Jha; K. Prasad

Advanced Materials Letters, 2014, Volume 5, Issue 9, Pages 501-505
DOI: 10.5185/amlett.2014.4563

 Biosynthesis and characterizations of nanoparticles has become an important branch of nanotechnology nowadays. In this paper, green synthesis of silver nanoparticles (AgNPs) using the alcoholic extract of Argemone mexicana Linn. as a reducing and stabilizing agent, has been discussed. This biosynthetic method is simple, cost-effective and reproducible. Formation of AgNPs was established by X-ray diffraction, transmission electron microscopy and UV-Visible spectroscopic techniques. Nanoparticles almost spherical in shape having a size of 2-6 nm are found. UV-visible study revealed the surface plasmon resonance at 414 nm. A possible involved mechanism for the biosynthesis of silver nanoparticles has also been proposed.  Further, it was found that AgNPs sol when applied to the SiHa cancer cell line was found to inhibit the growth by 70-80%. It is cumulative effect of the unutilized plant extract and nanosilver. The work signifies the importance of medicinal plants in synthesis of nanomaterials as it bestows double benefit in terms of drug delivery as well as safety. It may open a fresh avenue in future cancer therapeutics.

Synthesis Of (Ag0.5Fe0.5)TiO3 Nanocrystalline Powder Using Stearic Acid Gel Method

Sandeep Kumar; L. K. Sahay; Anal K. Jha; K. Prasad

Advanced Materials Letters, 2014, Volume 5, Issue 2, Pages 67-70
DOI: 10.5185/amlett.2013.fdm.06

A low-cost, green and reproducible stearic acid assisted synthesis of nanocrystalline powder of (Ag0.5Fe0.5)TiO3 (n-AFT) is reported. X-ray, FTIR, energy dispersive X-ray and transmission electron microscopy analyses are performed to ascertain the formation of n-AFT. Rietveld refinement of X-ray data indicated the formation of a single-phase monoclinic structure. Individual nanoparticles almost spherical in shape having the sizes of 5-14 nm are found. The mechanism of nanotransformation for the soft-chemical synthesis of n-AFT has been explained using nucleation and growth theory. UV-visible study revealed the surface plasmon resonance at 318 nm. Dielectric study revealed a low value of dielectric constant (= 177) and dielectric loss (= 0.013) at 1 kHz. Magnetic studies have been carried out using vibration sample magnetometer, which indicated the possibility of magnetoelectric coupling.

Sunlight Induced Rapid Synthesis And Kinetics Of Silver Nanoparticles Using Leaf Extract Of Achyranthes Aspera L. And Their Antimicrobial Applications

T. Peter Amaladhas; M. Usha; S. Naveen

Advanced Materials Letters, 2013, Volume 4, Issue 10, Pages 779-785
DOI: 10.5185/amlett.2013.2427

Sunlight induced strategy for the rapid green synthesis of silver nanoparticles (AgNPs) is reported for the first time using aqueous leaf extract of Achyranthes aspera. On exposing a mixture of silver nitrate solution and aqueous leaf extract of A. aspera to sunlight, stable silver nanoparticles were obtained within few seconds. The water soluble biomolecules from the A. aspera served as both reducing and capping agents in the synthesis of silver nanoparticles. The nanoparticles were characterized using UV–Vis., Fourier transform infrared (FTIR), transmission electron microscopy (TEM), and EDAX techniques. The pseudo first order rate constant kobs, for the formation of AgNPs was found to be 3.49 x 10 -2 min -1 . The particles were stable for 3 months. The nanoparticles were mono-dispersed, spherical in shape with the average size of 12.82 nm. FT-IR analysis revealed that the -OH groups, possibly, from saponin were responsible for the reduction of silver ions to silver nanoparticles (AgNPs). Thus prepared AgNPs have desirable cytotoxicity towards bacterial strains and fungus and the effect was compared with standard drugs, Amikacin and fluconazole respectively. This green and mild technique can be used for the large scale extracellular synthesis of silver nanoparticles and the AgNPs thus prepared may be used for biological applications.

Green Synthetic Route For The Size Controlled Synthesis Of Biocompatible gold Nanoparticles Using Aqueous Extract Of Garlic (Allium Sativum) 

Lori Rastogi;J. Arunachalam

Advanced Materials Letters, 2013, Volume 4, Issue 7, Pages 548-555
DOI: 10.5185/amlett.2012.11456

A green synthetic approach for the highly stable, size controlled synthesis of gold nanoparticles is being described. The study explores the use of aqueous extract of garlic cloves as reducing/stabilizing agent for the synthesis of gold nanoparticles. The synthesis is achieved by heating the mixture of aqueous garlic extract and HAuCl4 at 95ºC in water bath at pH-10 for 2 hrs. The formation of gold nanoparticles was confirmed from the appearance of pink color and an absorption maximum at 530 nm. Further, extract concentration and type of alkali (NH4OH/NaOH) has been varied to tune the size of nanoparticles. The size of the synthesized gold nanoparticles was found to decrease (56.5 ± 13.6 to 24.7 ± 8.2) with increasing extract concentration (0.5%-1.0%) in the presence of NH4OH. In the presence of NaOH, the synthesis time was reduced to 20 min, with an average particle size of 5.5 ± 2.7. Transmission electron microscopy analysis indicated that non-aggregated gold nanoparticles of various sizes could be synthesized by simple change in reaction conditions. The synthesized gold nanoparticles were found to be pure face centered cubic crystals as suggested by selected area electron diffraction and X-ray diffraction patterns. Fourier transform infrared spectroscopy revealed possible role of S-allyl-cysteine as the major component responsible for reduction of Au 3+ to Au 0 and protein/amino acids as stabilizing agents. The gold nanoparticles were found to have remarkable in vitro stability: showed no sign of aggregation at room temperature storage for a long time (more than 6 months), could resist aggregation in aqueous media with high concentrations of NaCl, in various buffers including: cysteine, histidine, bovine serum albumin and at host of pH ranges. Further, cytotoxicity evaluations on S. cerevisiae have shown non-toxic nature of the synthesized gold nanoparticles up to 100 µM of concentration as assessed by well diffusion and inhibition of colony forming efficiency assay. Ease in size control, high stability and biocompatible nature of garlic extract reduced, stabilized gold nanoparticles suggests that they could be potential candidates for drug delivery applications.

Green Synthesis Of Gold Nanoparticles Using Camellia Sinensis And Kinetics Of The Reaction

Sontara Konwar Boruah; Chitrani Medhi;Okhil Kumar Medhi; Prabin Kumar Boruah; Pradyut Sarma

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 481-486
DOI: 10.5185/amlett.2012.icnano.103

In this paper we report the green synthesis of gold nanoparticles (AuNPs) by using a simple, faster, low cost, eco-friendly technique. The green synthesis of AuNPs was done by using fresh young leaves and leaf buds of tea (Camellia Sinensis). Reduction of HAuCl4 by polyphenols present in young leaves and leaf buds of tea extract at room temperature provides AuNPs (Au 3+ →Au 0 ).The UV-Visible absorption spectrum of AuNPs in tea extract shows two bands at around 534 and 752 nm, which results from transverse and longitudinal surface plasmon resonance (SPR) respectively. In fluorescence spectroscopy study, AuNPs in tea extract shows fluorescence emission at 450 and 705 nm when excited at 350 nm. The kinetics of the reaction rate (Au 3+ →Au 0 ) with respect to time was studied with the help of UV-Visible and fluorescence spectroscopy. The reaction rate evaluated with the help of UV-Visible and fluorescence spectroscopy was found to be almost similar in results. The kinetics of the reaction also suggests that the reaction was fast and completed in 28 minutes. The amount of tea extract determines the core size of the AuNPs. The core size of the AuNPs decreases as the amount of tea extract increases and it causes the blue-shift of SPR band. The physical properties, particle size and morphology of AuNPs were characterized using X-ray diffractometer (XRD), field emission scanning electron microscope (FESEM) and high resolution-transmission electron microscopy (HR-TEM) techniques. The AuNPs size in the range ~2.94-45.58 nm with an average of 13.14 nm.

Evidence Based Green Synthesis Of Nanoparticles

Anamika Mubayi; Sanjukta Chatterji; Prashant K. Rai; Geeta Watal

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 519-525
DOI: 10.5185/amlett.2012.icnano.353

Nowadays, nanotechnology has grown to be an important research field in all areas including medicinal chemistry. The size, orientation and physical properties of nanoparticles have reportedly shown to change the performance of any material. For several years, scientists have constantly explored different synthetic methods to synthesize nanoparticles. On the contrary, the green method of synthesis of nanoparticles is easy, efficient, and eco-friendly in comparison to chemical-mediated or microbe-mediated synthesis. The chemical synthesis involves toxic solvents, high pressure, energy and high temperature conversion and microbe involved synthesis is not feasible industrially due to its lab maintenance. Since, green synthesis is the best option to opt for the synthesis of nanoparticles, therefore the nanoparticles were synthesized by using aqueous extract of Moringa oleifera and metal ions (such as silver). Silver was of particular interest due to its distinctive physical and chemical properties. M. oleifera leaf extract was selected as it is of high medicinal value and it does not require any sample preparation and hence is cost-effective. The fixed ratio of plant extract and silver ions were mixed and kept at room temperature for reduction. The color change from yellow to reddish brown confirmed the formation of nanoparticles. Further, the synthesized nanoparticles were characterized by UV, EPMA, XRD and FTIR data. The antimicrobial activity of synthesized nanoparticle has also been examined in gram positive and gram negative bacteria and encouraging results are in hand.