Keywords : Gold nanoparticles


Antifungal Activity of Iron-gold and Cobalt-gold co-doped ZnO Nanoparticles

A. Ferin Fathima; R. Jothi Mani; K. Sakthipandi

Advanced Materials Letters, 2021, Volume 12, Issue 6, Pages 1-5
DOI: 10.5185/amlett.2021.061636

Zn0.98Fe0.01Au0.01O and Zn0.98Co0.01Au0.01O nanoparticles (NPs) have been synthesized via poly ethylene glycol assisted route. The average crystallite size of Zn0.98Fe0.01Au0.01O and Zn0.98Co0.01Au0.01O NPs were estimated from X-ray diffraction results and the values are 31.38 nm and 36.14 nm respectively. The UV absorption spectra confirmed the formation of the NPs with the characteristic peaks at 374 and 366 nm respectively. This spectral observation indicates that the band gap of ZnO nanoparticles decreases by doping iron/gold and cobalt/gold nanoparticles. The morphology and elemental composition of Zn0.98Fe0.01Au0.01O and Zn0.98Co0.01Au0.01O NPs were investigated. The antifungal activity of synthesized Zn0.98Fe0.01Au0.01O and Zn0.98Co0.01Au0.01O NPs were found against four postharvest pathogenic fungi like Aspergillus niger, Aspergillus flavus, Rhizopus microsporus and Pencillium sp < /em>. The doping of iron and gold in ZnO nanoparticles enhances the zone of inhibition for the fungal pathogens compared to pure ZnO nanoparticles. Antifungal activity of Zn0.98Fe0.01Au0.01O and Zn0.98Co0.01Au0.01O nanoparticles were higher when compared with standard antibiotic mycostatin whose zone of inhibition is 18 mm against Aspergillus niger, Aspergillus flavus, Rhizopus microsporus and Pencillium sp.

Synthesis and Characterization of Gold Nanoparticles from Lobelia Nicotianifolia Leaf Extract and its Biological Activities

M.B. Lava; Uday M. Muddapur; B. Nagaraj

Advanced Materials Letters, 2020, Volume 11, Issue 3, Pages 1-4
DOI: 10.5185/amlett.2020.031491

Biosynthesis of gold nanoparticles is one among the best and cheap economical viable process, which is environmental friendly. The purpose of this study is to synthesis the gold nanoparticles using Lobelia nicotianifolia leaf extract and to investigate its biological activities. The synthesized gold nanoparticles were characterized by UV-vis spectroscopy, TEM, SAED, FTIR and XRD, the nanoparticles produced at maximum absorbance 532 nm. The Characterization study proved that the size and shape of AuNPs were spherical in shape, with an average size of 80 nm. Synthesized AuNPs were evaluated for various in-vitro biological studies.

Preparation, stabilization, and self-assembly of gold nanoparticles by Chitosan derivatives

Jia-Jia Shen; Jia He; Ya Ding

Advanced Materials Letters, 2019, Volume 10, Issue 2, Pages 80-84
DOI: 10.5185/amlett.2019.2016

Gold nanoparticles (GNPs) are of unique and interesting materials being firstly reported 100 years ago. They are one of the most widely studied nanomaterials potential for disease cure. To improve the colloidal stability, biocompatibility, and hemocompatibility of GNPs, chitosan (CS), a naturally produced polysaccharide with excellent biocompatibility and biodegradation, has been modified to generate water-soluble derivatives and used as the stabilizing agent of GNPs. In the presence of these derivatives, GNPs are stabilized, functionalized, and assembled via electronic static and covalent bond interactions. Based on these works, GNPs with different dimensional, morphology, and crystal lattice are obtained, which can be further apply to a variety of applications in sensing, imaging, therapy, and catalysis. 

Sensitivity enhanced photo-thermal borders detection in bio-phantoms enriched with gold nanoparticles

Yossef Danan; Ariel Schwarz; Moshe Sinvani; Zeev Zalevsky

Advanced Materials Letters, 2018, Volume 9, Issue 7, Pages 471-475
DOI: 10.5185/amlett.2018.1860

In the last decade diversity of applications in the fields of diagnostics and treatment for biomedical applications using gold nanoparticles (GNPs) as contrast agent sprang up. The strong optical absorption and scattering properties of the GNPs due to their localized surface plasmon resonance (LSPR) effect enables their use as contrast agents in these applications. The usage of the light-scattering properties of the GNPs in most imaging methods lead to background noise stems from light scattering from the tissue due to the same wavelengths of the illumination source and the GNPs’ scattering. In our previous works we presented a method to improve border detection of bio-phantoms enriched with GNPs leading for real-time complete tumor resection by using a modulated laser illumination, photo thermal imaging camera and the optical absorption of specially targeted GNPs. In this system the thermal camera detects the temperature field of the illuminated bio-phantoms. Although the surrounding area got heated the border location was detected at a precision of at least 0.5 mm through use of a simple post processing technique. In this paper, we present a continuation of our previous research with modified system of time sequence labelling (TSL) processing for improved border detection capable of operating and detecting borders at much lower signal to noise levels.

Gold nanoparticle-based biosensors for the assay of tumor marker proteins with clinical applications

Jiehua Ma; Xiaolu Hu; Yaqin Tao; Chao Li; Xiaoxia Mao; Genxi Li

Advanced Materials Letters, 2017, Volume 8, Issue 12, Pages 1125-1131
DOI: 10.5185/amlett.2017.1552

The detection of tumor markers plays an important role in clinical diagnosis and evaluation of therapeutic effect. Early detection of tumor markers, which are usually proteins, can greatly facilitate effective treatment with different modalities and even increase cure rate of patients. Currently, nanoparticle-based methods for cancer diagnostics are becoming an increasingly relevant alternative to traditional techniques. Gold nanoparticles (AuNPs) are one of the most extensively studied nanomaterials due to their remarkable physical and chemical properties. With the recent advances in nanotechnology, AuNPs have offered new ways to detect tumor markers at low concentrations and to target cancer cells in very deep sites. The use of AuNPs may increase the sensitivity of a biosensor and generate higher accuracy and precision of the assays. So, AuNPs have greatly facilitated the development of nanomaterials-based technology for clinic diagnostics and therapy. In this review paper, we have summarized different kinds of AuNPs-based biosensors for the detection of tumor marker proteins with a particular focus on optical and electrochemical techniques, which may provide valuable perspective for the colleagues in the related communities.

Fabrication Of High Stable Gold Nanofluid By Pulsed Laser Ablation In Liquids

R. Torres-Mendieta; R. Mondrag

Advanced Materials Letters, 2015, Volume 6, Issue 12, Pages 1037-1042
DOI: 10.5185/amlett.2015.6038

Laser ablation in liquids by femtosecond radiation has been used to generate gold nanoparticles in a heat transfer fluid to produce a high stable thermal nanofluid as a heat transfer intensification technique. In oil based fluids, no matter the actual fabrication route, nanoparticles tend to agglomerate. Here, we report a new form to control its stability through the addition of a surfactant that does not degrade at high temperatures. It allow us to produce gold nanoparticles of 58±31 nm in the liquid in situ, avoiding in this way the generation of pollution and reducing the maximum point of nanoparticle agglomeration at 370 nm. The developing of this new nanofluid represents a great opportunity for the harvesting of solar energy industry.

Structural And Electrical Properties Of Self-standing Polyaniline Films Modified With Gold Nanoparticles 

Sonika Thakur; Anupinder Singh; Lakhwant Singh

Advanced Materials Letters, 2015, Volume 6, Issue 9, Pages 840-846
DOI: 10.5185/amlett.2015.5917

Self-standing polyaniline (Pani) films modified with gold nanoparticles (Au NP’s), where Au NP’s are added in different successive weight percents, have been synthesized by conventional chemical polymerization technique. An in-depth investigation of the structural and electrical characteristics of prepared films has been conducted using various characterizations. The X-ray diffraction (XRD) validates the presence of Au NP’s in Pani and the results are supported well by energy dispersive X-ray analyzer (EDX). The field emission scanning electron microscopy (FESEM) clearly shows thorough dispersion of Au NP’s in the amorphous host matrix with minor aggregation. The Fourier transform infrared red (FTIR) studies give the information of possible chemical interaction between the nanoparticles and polymer which is in good agreement with charge transfer mechanism proposed in the manuscript. The temperature dependent dc electrical conductivity has been observed to depend strongly on the nanoparticle loading and follows Mott’s three-dimensional variable range hopping (3D VRH) conduction mechanism. Parameters obtained from Hall Effect measurements are of same order as is calculated by dc measurements which indicates a very good corroboration of results. Higher ac conductivity, dielectric constant and dielectric loss of nanocomposites have also been observed as compared to that of pure Pani.

In-situ Electrochemical Synthesis Of Prussian Blue Composite With Gold Nanoparticles And Its Application In Hydrogen Peroxide Biosensor

Suman Singh; D. V. S. Jain; M. L. Singla

Advanced Materials Letters, 2015, Volume 6, Issue 9, Pages 760-767
DOI: 10.5185/amlett.2015.5796

This manuscript presents in-situ electrochemical synthesis of Prussian Blue-gold nanoparticles (PB- AuNPs) composite for application in hydrogen peroxide (H2O2) biosensor. The SEM image clearly showed the presence of AuNPs of size in range of 50 to 200 nm spread on PB matrix. UV-Visible spectra showed absorbance peak at 530 nm corresponding to AuNPs and a hump in 690-740 nm region for PB, confirming the synthesis of composite. The cyclic voltammetry (CV) showed the surface coverage of 3.65 x 10 -9 mol/cm 2 for pure PB film and 4.33 x 10 -9 mol/cm 2 for PB-AuNPs film, with diffusion coefficient of 1.19 x 10 -9 cm 2 /s, and 5.64 x 10 -9 cm 2 /s respectively. The film thickness is found to be 2.4 x 10 -12 cm for PB and 2.9 x 10 -12 cm for PB-AuNPs composite. The concentration of redox active centers (Fe +3/+2 ) is 3.5 moles/cm 3 for ITO/PB and 4.1 moles/cm 3 for ITO/PB-AuNPs respectively. The CV of ITO/PB showed one redox couple at 0.118 V and 0.215 V, whereas with ITO/PB-AuNPs electrode, two sets of well-defined redox peaks; (i) 0.095 V & 0.135 V and (ii) 0.74 V & 0.78 V were obtained. The faradic current obtained with ITO/PB was 3.6 x 10 -3 A and 7.3 x 10 -3 A for ITO/PB-AuNPs composite film, respectively. The faradic current was almost double in presence of gold nanoparticles, as compared to pure PB. For H2O2 biosensor, the horse radish peroxidase (HRP) was immobilized on composite film and was used for H2O2 detection. The linearity was obtained from 10 to 90 nM, with sensitivity of 0.73µA/nM and the apparent Km value was 45 nM. The response time of reported biosensor is 20 sec and is stable for about three months.

Peroxidase Assisted Biosynthesis Of Silver And Gold Nanoparticles: Characterization And Computational Study

Abhijeet Mishra; Poonam Singh; Meryam Sardar

Advanced Materials Letters, 2015, Volume 6, Issue 3, Pages 194-200
DOI: 10.5185/amlett.2015.5658

In this paper, we described a simple and single step procedure for the synthesis of horseradish peroxidise enzyme (HRP) capped silver and gold nanoparticles. HRP, a heme-containing enzyme utilises hydrogen peroxide to oxidise a wide variety of organic and inorganic compounds. The biosynthesized nanoparticles were characterized by means of UV-VIS spectroscopy, Dynamic light scattering (DLS), Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). FTIR study confirms the presence of peroxidase enzyme on the nanoparticles. Computational studies reveal that exposed amino acids (viz serine, threonine, arginine and glycine) play key role in reduction and as well as stabilization of nanoparticles. The HRP assisted silver and gold nanoparticles retained its biological activity in the nanoparticles. The study indicates that Peroxidase which is found in almost all the plants can be used for the large scale synthesis of nanoparticles. Moreover additional attraction is the retention of the enzymatic activity on the nanoparticles. In a single step reaction enzyme is catalysing and in doing so it gets immobilized on it. The integration of biomolecules to nanoparticles is a tedious method mainly due to the surface of nanoparticles. Functionalization of noble metal nanoparticles with biomolecules (e.g., protein and DNA) is in demand because such systems possess numerous applications in catalysis, delivery, therapy, and imaging, sensing and controlling the structure of biomolecules. Computational study highlighted the amino acids which are interacting with the metal ions, thus synthetic peptides can also be designed to synthesize the metal nanoparticles.

Green Synthesis Of Gold Nanoparticles For controlled Delivery

S. Malathi; M. D. Balakumaran; P. T. Kalaichelvan; S. Balasubramanian

Advanced Materials Letters, 2013, Volume 4, Issue 12, Pages 933-940
DOI: 10.5185/amlett.2013.5477

Gold nanoparticles (AuNPs) have been synthesized by green method using chitosan as a reducing/capping agent. We designed a biocompatible carrier for controlled release of hydrophobic drugs. The designed carrier was prepared by using single oil-in-water (O/W) emulsion. The resulting AuNPs were characterized by UV–Vis spectroscopy (UV–Vis) and Fourier transform infrared spectroscopy (FTIR). The transmission electron microscopy (TEM) studies indicate the spherical nature of drug loaded nanoparticles with the size of 50nm while the average particle size of AuNPs is found to be 2-3nm. The chitosan capped AuNPs showed a surface plasmon resonance at 526nm. The FTIR spectra suggest that the amine group is mainly responsible for the reduction of tetrachloroauric acid and capping the AuNPs. The controlled release of rifampicin (RIF) was investigated by in vitro studies using phosphate buffer saline (PBS) at pH=7.4. The loading efficiency of drug molecule was found to be 71%. The encapsulated drugs were released at 37 °C temperature. The results have been fit into various mechanistic models and it is found that the Higuchi model fits in to the release behavior of RIF. Further, the antibacterial activity of RIF loaded nanoparticles was examined by Gram +ve (bacillus subtils) and Gram -ve (Pseudomonas aeruginosa) bacteria. The application of similar drug loaded nanocarrier for treating other diseases like cancer can also be investigated.

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.

In-situ TEM Observation Of Electron Irradiation Induced Shape Transition Of Elongated Gold Nanoparticles Embedded In Silica

S. Mohapatra; J. Ghatak;D.K. Avasthi; Y.K. Mishra

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 444-448
DOI: 10.5185/amlett.2012.ib.111

Elongated Au nanoparticles (NPs) embedded in silica matrix were fabricated by 100 MeV Ag ion irradiation of 3 MeV Au ion implanted SiO2/Si(100) substrates, annealed at 1050 o C. Electron-beam-induced shape evolution of elongated Au NPs embedded in SiO2 has been studied by high resolution transmission electron microscopy. Electron beam irradiation resulted in a decrease in the aspect ratio of Au NPs from ~ 1.4 to 1 with increase in irradiation time. The observed ellipsoidal-to-spherical shape transition of Au NPs has been ascribed mainly to the cumulative effects of electron beam induced heating, softening of silica matrix and radiation enhanced diffusion of knock-on displaced O and Si atoms, resulting in local stress relaxation.

Plant Mediated Synthesis Of Gold Nanoparticles Using Fruit Extracts Of Ananas Comosus (L.) (Pineapple) And Evaluation Of Biological Activities

Nagaraj Basavegowda; Agnieszka Sobczak-Kupiec; Dagmara Malina; Yathirajan HS; Keerthi V R; Chandrashekar N; Salman Dinkar; Liny P

Advanced Materials Letters, 2013, Volume 4, Issue 5, Pages 332-337
DOI: 10.5185/amlett.2012.9423

AnchorPlant mediated synthesis of metallic nanoparticles is an increasing commercial demand due to the wide applicability in various areas such as electronics, catalysis, chemistry, energy, cosmetics and medicine. In the present investigation, synthesis of gold nanoparticles is done by using fruit extracts of Ananas comosus (L.). Nanoparticles were characterized by using UV visible absorption spectra. Their morphology, elemental composition and crystalline phase were determined by scanning electron microscopy, energy dispersive X-ray spectroscopy and selected area electron diffraction. FT-IR analysis was used to confirm the presence of gold nanoparticles in the extracts. The synthesized gold nanoparticles were generally found to be effective as antimicrobial agents against some important human pathogens like E.coli and Streptobacillus sp. which are affecting and cause diseases like food poisoning and rat-bite fever to human beings respectively.

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.

Biocompatible Synthesis Of Silver And Gold Nanoparticles Using Leaf Extract Of Dalbergia Sissoo 

Chandan Singh; Ritesh K. Baboota; Pradeep Kr Naik; Harvinder Singh

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 279-285
DOI: 10.5185/amlett.2011.10312

This report presents a rapid, reproducible and a green biogenic approach for the biosynthesis of gold and silver nanoparticles using leaf extract of Dalbergia sissoo. The biomolecules present in the plant induced the reduction of Au 3+ and Ag + ions from HAuCl4 and AgNO3 respectively, which resulted in the formation of Dalbergia conjugated nanoparticles. The growth of nanoparticles was monitored by UV-vis spectrophotometer that demonstrated a peak at 545 and 425 nm corresponding to Plasmon absorbance of gold and silver nanoparticles respectively. The leaf extract was found to direct different shape and sized gold nanoparticles. Gold nanoparticles were 50-80 nm in size and their shape varied from spherical to few triangular and hexagonal polyshaped. While silver nanoparticle synthesized were spherical, in the range of 5-55 nm in size. X-ray diffraction studies corroborated that the biosynthesized nanoparticles were crystalline gold and silver. Fourier transform infra-red spectroscopy analysis revealed that biomolecules were involved in the synthesis and capping of silver nanoparticles and gold nanoparticles.

Voltammetric Detection Of Microcystis Genus Specific-sequence With Disposable Screenprinted Electrode Modified With Gold Nanoparticles

Minbo Lan; Chen Chen; Qin Zhou; Yuanjie Teng; Hongli Zhao; Xiangheng Niu

Advanced Materials Letters, 2010, Volume 1, Issue 3, Pages 217-224
DOI: 10.5185/amlett.2010.

A disposable electrochemical biosensor for detection of DNA sequence related to Microcystis was described. After depositing gold nanoparticles (AuNPs) onto a screen-printed carbon electrode (SPCE) surface by electrodeposition, the DNA probe which is complementary to a specific gene sequence related to Microcystis was immobilized onto the AuNPs modified SPCE via a thiol linker at the 5’ end. On the electrode surface the immobilized single-stranded DNA could undergo hybridization in the solution containing DNA specific-sequence of Microcystis. Using methylene blue as the indicator, DNA immobilization and hybridization were characterized by cyclic voltammetry and differential pulse voltammetry. Parameters, such as the deposition conditions of gold nanopariticle and the preconcentration time of MB, were optimized. In addition, the control experiments with non-complementary and single base mismatch sequences were investigated and results demonstrated the high selectivity of the biosensor.

Tailoring The Size Of Gold Nanoparticles By Electron Beam Inside Transmission Electron Microscope

Y. K. Mishra; S. Mohapatra; D. K. Avasthi; N. P. Lalla; Ajay Gupta

Advanced Materials Letters, 2010, Volume 1, Issue 2, Pages 151-155
DOI: 10.5185/amlett.2010.4116

Au nanoparticles (NPs) embedded in silica matrix were synthesized by atom beam co-sputtering and investigated in detail by transmission electron microscopy (TEM). A study on electron beam induced tailoring of size of Au nanoparticles has been performed in an in-situ TEM experiment as a function of electron irradiation time. This study concludes that electron beam irradiation can result in a controlled growth of NPs in proportion to irradiation fluence. Analytical calculations for electron energy loss in Au NPs and fused silica have been performed, which indicate that the observed growth of Au NPs in present case is due to rise in temperature of Au NPs and surrounding silica.