scholarly journals Colorimetric Detection of Organophosphate Pesticides Based on Acetylcholinesterase and Cysteamine Capped Gold Nanoparticles as Nanozyme

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 8050
Author(s):  
Muhammad Musaddiq Shah ◽  
Wen Ren ◽  
Joseph Irudayaraj ◽  
Abdulrahim A. Sajini ◽  
Muhammad Ishtiaq Ali ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Detection System ◽  
Colorimetric Detection ◽  
Blue Colour ◽  
Buffer Solution ◽  
Site Monitoring ◽  
Transmission Electron ◽  
Detection Assay ◽  
Acetylcholine Chloride ◽  
Average Size

Organophosphates (OPs) are neurotoxic agents also used as pesticides that can permanently block the active site of the acetylcholinesterase (AChE). A robust and sensitive detection system of OPs utilising the enzyme mimic potential of the cysteamine capped gold nanoparticles (C-AuNPs) was developed. The detection assay was performed by stepwise addition of AChE, parathion ethyl (PE)-a candidate OP, acetylcholine chloride (ACh), C-AuNPs, and 3, 3′, 5, 5′-tetramethylbenzidine (TMB) in the buffer solution. The whole sensing protocol completes in 30–40 min, including both incubations. The Transmission Electron Microscopy (TEM) results indicated that the NPs are spherical and have an average size of 13.24 nm. The monomers of C-AuNPs exhibited intense catalytic activity (nanozyme) for the oxidization of TMB, revealed by the production of instant blue colour and confirmed by a sharp peak at 652 nm. The proposed biosensor’s detection limit and linear ranges were 5.8 ng·mL−1 and 11.6–92.8 ng·mL−1, respectively, for PE. The results strongly advocate that the suggested facile colorimetric biosensor may provide an excellent platform for on-site monitoring of OPs.

scholarly journals Synthesis and characterization of gold nanoparticles on titanium dioxide for the catalytic photodegradation of 2,4-dichlorophenoxyacetic acid

2018 ◽  
Vol 16 (5) ◽  
Author(s):  
E. Romero Torres ◽  
M. Gutiérrez Arzaluz ◽  
V Mugica Alvarez ◽  
L. González Reyes ◽  
M. Torres Rodríguez ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Titanium Dioxide ◽  
Uv Light ◽  
Anatase Phase ◽  
Precipitation Method ◽  
Dichlorophenoxyacetic Acid ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Average Size ◽  
2,4 Dichlorophenoxyacetic Acid

The photocatalytic degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) using a Au/TiO2 catalyst and ultraviolet (UV) light energy source (9 mW/cm2) discussed. Gold nanoparticles were synthesized by controlled urea reduction and deposited on titanium dioxide (TiO2) by the deposition-precipitation method. The average size of the nanoparticles was 6-8 nm. X-ray diffraction (XRD) characterization confirmed that TiO2 was present in the anatase phase, whereas the presence and particle size of gold were determined by transmission electron microscopy (TEM). The results of the degradation showed that the activity of TiO2 was improved when Au nanoparticles were present on the surface. The reactions were performed at atmospheric pressure and room temperature.

Microwave-Assisted Synthesis of Unmodified Gold Nanoparticles for Colorimetric Detection of Dopamine

2017 ◽  
Vol 730 ◽  
pp. 167-171 ◽  
Author(s):  
Ekarat Detsri ◽  
Kanrayasiri Kamhom ◽  
Chatsuda Detsri
Keyword(s):  
Gold Nanoparticles ◽  
Sodium Citrate ◽  
Limit Of Detection ◽  
Signal To Noise Ratio ◽  
Chemical Reduction ◽  
Colorimetric Detection ◽  
Random Coil ◽  
Microwave Assisted Synthesis ◽  
Microwave Assisted ◽  
Transmission Electron

Unmodified gold nanoparticles (AuNPs) have been successfully synthesized by the chemical reduction of tetrachloride gold (III) ions ([AuCl4]-) in the presence of sodium citrate based on the rapid microwave−assisted approach. The diameter of the synthesized nanoparticles was found in the range of 16.50±2.75 nm. The AuNPs were characterized using UV−vis spectrophotometer, zeta potential analyzer and transmission electron microscope (TEM). The sodium citrate protected AuNPs were found to be selective and sensitive for the detection of dopamine. It was based on the aggregation change of the nanoparticles from random coil to hairpin structure upon the addition of dopamine concentration. The red shift of the plasmonic peak wavelength of AuNPs could be used for the detection of dopamine. The response to dopamine allows for a linear range from 10 to 125 mg⋅L-1 (R2 = 0.9804) with a limit of detection (LOD) at a signal to noise ratio of 3 of 12.85±1.38 mg⋅L-1. The colorimetric sensor was evaluated with 98.0−99.9% recovery of added dopamine in urine sample. The proposed sensor was successfully applied to the determination of dopamine in biological samples.

Fullerene C60 Films Cross-Linked with Octane-1,8-Dithiol: Preparation, Characterization and the Use as Template for Chemical Deposition of Gold Nanoparticles

2008 ◽  
Vol 8 (8) ◽  
pp. 3828-3837 ◽  
Author(s):  
Víctor Meza-Laguna ◽  
Elena V. Basiuk ◽  
Edgar Alvarez-Zauco ◽  
Taras Yu. Gromovoy ◽  
Oscar Amelines-Sarria ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Density Functional ◽  
Chemical Deposition ◽  
Density Functional Theory Calculations ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Covalent Bonds ◽  
Transmission Electron ◽  
Average Size ◽  
20 Nm

We report on the preparation of fullerene C60 thin films chemically cross-linked with octane-1,8-dithiol, which are capable of binding gold nanoparticles. The formation of a polymer was directly proved by means of laser desorption/ionization time-of-flight mass spectra, in which we observed the cleavage of fullerene–dithiol polymer at different bonds. Fourier-transform infrared, Raman and UV-visible spectra of the functionalized films exhibited notorious changes due to the formation of new covalent bonds between C60 molecules and bifunctional thiol. We further demonstrated that the dithiol-functionalized fullerene can be employed as a support for stable and homogeneous deposition of gold nanoparticles. Their average size is about 5 nm according to high-resolution transmission electron microscopy observations, and up to 20 nm, as found from scanning tunneling microscopy images. The proposed binding mechanism is through a strong coordination attachment between Au nanoclusters and sulfur donor atoms of the functionalized fullerene, as supported by density functional theory calculations.

scholarly journals Dietary Fiber-Tethered Gold Nanoparticles: An Innovative Analytical Tool for Probing Interactions

2021 ◽  
Vol 2 (2) ◽  
pp. 497-518
Author(s):  
Cristina Lupo ◽  
Samy Boulos ◽  
Chiara Delle Vedove ◽  
Fabian Gramm ◽  
Laura Nyström
Keyword(s):  
Gold Nanoparticles ◽  
Dietary Fiber ◽  
Detection System ◽  
Epidemiological Studies ◽  
Daily Consumption ◽  
Potential Health ◽  
Ligand Density ◽  
Gold Core ◽  
Transmission Electron ◽  
Novel Method

Epidemiological studies have recognized that daily consumption of dietary fiber-containing foods reduces the incidence of developing many chronic diseases, for example, by interacting with nutritionally relevant compounds. The low affinity nature that some of these interactions can have make the development of an analytical detection system for their study particularly difficult. Therefore, the mechanism of action of binding compounds, by which a dietary fiber exerts its potential health benefits, remains largely unknown. Here, a novel method based on glyco-nanotechnology is proposed for studying the interaction between galactomannan and target molecules. Starting from a bottom-up approach, gold nanoparticles and thiolated galactomannans of two different sizes were synthesized separately, and then mixed for auto-assembly of the two glyconanoparticle materials. In addition, a preliminary interaction study between the prepared glyconanoparticles and Concanavalin A was carried out using transmission electron microscopy (TEM) from which it could be deduced that the molecular weight and ligand density on the gold core play an important role in the interaction. Therefore, dietary fiber-tethered gold nanoparticles are a valuable tool to elucidate key parameters underlying dietary fiber interactions.

scholarly journals Microwave-Mediated Rapid Synthesis of Gold Nanoparticles Using Calotropis procera Latex and Study of Optical Properties

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Ratul Kumar Das ◽  
Punuri Jayasekhar Babu ◽  
Nayanmoni Gogoi ◽  
Pragya Sharma ◽  
Utpal Bora
Keyword(s):  
Gold Nanoparticles ◽  
Room Temperature ◽  
Spectroscopic Studies ◽  
Organic Coating ◽  
Calotropis Procera ◽  
Ftir Analysis ◽  
Spherical Nanoparticles ◽  
Transmission Electron ◽  
Crystalline Nature ◽  
Average Size

We report a microwave-mediated simple and rapid method of gold nanoparticles (GNPs) synthesis using latex of Calotropis procera. UV-Vis spectroscopic studies indicated the formation of GNPs. The GNPs were stable at room temperature (25°C) for six months. Transmission electron microscope (TEM) micrographs of the synthesized GNPs showed the formation of spherical nanoparticles with an average size of 13 ± 5 nm. SAED and XRD confirmed the crystalline nature of GNPs. Fourier transform infrared (FTIR) analysis indicated the presence of organic coating on the nanoparticles. Cytotoxicity of the GNPs was tested on HeLa and A549 and found to be nontoxic which was indicating that latex of Calotropis procera provided the nontoxic coating on GNPs, thus can be used as biomedical and pharmacological applications.

scholarly journals Bactericidal Activity of Usnic Acid-Chitosan Nanoparticles against Persister Cells of Biofilm-Forming Pathogenic Bacteria

Marine Drugs ◽  
2020 ◽  
Vol 18 (5) ◽  
pp. 270
Author(s):  
Fazlurrahman Khan ◽  
Hongsik Yu ◽  
Young-Mog Kim
Keyword(s):  
Antibacterial Activity ◽  
Pathogenic Bacteria ◽  
Chitosan Nanoparticles ◽  
Usnic Acid ◽  
Spherical Shape ◽  
Bacterial Cells ◽  
Persister Cells ◽  
Buffer Solution ◽  
Transmission Electron ◽  
Average Size

The present study aimed to prepare usnic acid (UA)-loaded chitosan (CS) nanoparticles (UA-CS NPs) and evaluate its antibacterial activity against biofilm-forming pathogenic bacteria. UA-CS NPs were prepared through simple ionic gelification of UA with CS, and further characterized using Fourier transform infrared spectroscopy, X-ray diffraction, and field-emission transmission electron microscopy. The UA-CS NPs presented a loading capacity (LC) of 5.2%, encapsulation efficiency (EE) of 24%, and a spherical shape and rough surface. The maximum release of UA was higher in pH 1.2 buffer solution as compared to that in pH 6.8 and 7.4 buffer solution. The average size and zeta potential of the UA-CS NPs was 311.5 ± 49.9 nm in diameter and +27.3 ± 0.8 mV, respectively. The newly prepared UA-CS NPs exhibited antibacterial activity against persister cells obtained from the stationary phase in batch culture, mature biofilms, and antibiotic-induced gram-positive and gram-negative pathogenic bacteria. Exposure of sub-inhibitory concentrations of UA-CS NPs to the bacterial cells resulted in a change in morphology. The present study suggests an alternative method for the application of UA into nanoparticles. Furthermore, the anti-persister activity of UA-CS NPs may be another possible strategy for the treatment of infections caused by biofilm-forming pathogenic bacteria.

scholarly journals Synthesis of gold nanoparticles using Platycodon grandiflorum extract and its antipathogenic activity under optimal conditions

2020 ◽  
Vol 10 ◽  
pp. 184798042096169
Author(s):  
Periasamy Anbu ◽  
Subash CB Gopinath ◽  
S Jayanthi
Keyword(s):  
Electron Microscopy ◽  
Gold Nanoparticles ◽  
Plant Extracts ◽  
Photoelectron Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Platycodon Grandiflorum ◽  
Transmission Electron ◽  
Flower Plant ◽  
Average Size

Gold nanoparticles have many applications in the biomedical field, mainly for drug delivery, cancer therapy, and detection of pathogenic microorganisms. In this study, gold nanoparticles synthesized using Platycodon grandiflorum (Balloon flower plant) extracts were evaluated for their antibacterial potential. Gold nanoparticles were synthesized at 20–50°C using different volumes of the leaf extract. Biosynthesis of gold nanoparticles was confirmed by ultraviolet–visible spectral absorption at 545 nm by surface plasmon resonance. The morphology and size of the P. grandiflorum gold nanoparticles were further characterized as spherical in shape with an average size of 15 nm in diameter by scanning electron microscopy and transmission electron microscopy. Energy-dispersive X-ray analysis clearly displayed the presence of gold particles. The structural analysis results with face central cubic crystalline nature and elemental composition, including gold, were confirmed by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. In addition, Fourier transform infrared results identified the functional group in P. grandiflorum that is involved in the reduction of metal ions to gold nanoparticles. The synthesized P. grandiflorum gold nanoparticles exhibited efficient antibacterial activity against Escherichia coli (16 mm) and Bacillus subtilis (11 mm). This report confirms the synthesis of gold nanoparticle from balloon flower plant extracts, which can be used as a reducing and stabilizing agent and demonstrates its antibacterial applications.

A Simple and Rapid Method of Making 2D and 3D Arrays of Gold Nanoparticles

2006 ◽  
Vol 6 (3) ◽  
pp. 669-674 ◽  
Author(s):  
Carlos A. Fernandez ◽  
Chien W. Wai
Keyword(s):  
Gold Nanoparticles ◽  
Relative Size ◽  
Carbon Chain ◽  
Metal Nanoparticle ◽  
Carbon Chain Length ◽  
Transmission Electron ◽  
Carbon Coated ◽  
Average Size ◽  
Size Dispersion ◽  
2D And 3D

Monodispersive gold nanoparticles can be synthesized by a dropwise addition of a reducing agent microemulsion to a gold ion microemulsion followed by immediate stabilization with 1-decanethiol. No size-selective precipitations or digestive ripening procedures are necessary. There is no need for metal functionalization of the surfactant AOT. Gold nanoparticles with an average size of 3.8 nm and a relative size dispersion of 5.4% were observed using n-heptane as a solvent. It seems possible to adjust the nanoparticle size by small changes in the carbon chain length of the solvent. Self-assembled 2D and 3D arrays of gold nanoparticles with adjustable sizes have been obtained on carbon-coated copper grids and on a silicon wafer. The arrays have good crystallinity as evidenced by the external morphology and transmission electron diffraction results. The size of the gold nanoparticle 3D arrays depends on the immersion time and can be greater than 15 μm. This approach could be used to synthesize other noble metal nanoparticle arrays that may lead to new materials for electronic and photonic applications.

scholarly journals Synthesis of gold nanostar using chitosan as reductive agent by the seedless reduction method

2020 ◽  
Vol 4 (4) ◽  
pp. 760-766
Author(s):  
Khuong Quoc Vo ◽  
Hong Tong Thi ◽  
Phuong Phong Thi Nguyen ◽  
Phuc Thanh Hoàng
Keyword(s):  
Gold Nanoparticles ◽  
Structure Directing Agent ◽  
Gold Nanostars ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Ft Ir ◽  
Novel Method ◽  
Gold Nanostar ◽  
Average Size

The gold nanostars (AuNS) were prepared through seedless reductive method by using the natural biodegradable polymer chitosan acting both as the stabilizing and shape-directing agent, ascorbic acid as a reducting agent. This reaction synthesis was carried out at room temperature and facile conditions. In an effort to control the size and shape of AuNS, many experimental parameters were investigated for the thorough understanding the role of chitosan in the formation of gold nanostar. In this novel method, the pH condition and appropriate stabilizer concentration were crucial factors to prepare the well-defined AuNS. The obtained AuNS were characterized by many physical-chemistry analysis method such as transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy, dynamic light scattering (DLS), and X-Ray diffraction (XRD). The AuNS have an average size of about 55 nm and narrow size distribution when characterized by TEM images. UV-Vis spectroscopy of the gold nanoparticles colloidal solution showed the characteristic peaks at 587-700 nm, corresponding to the surface plasmon resonance of star-shaped nanostructure. The specific interactions between the functional groups of chitosan chain and the as-prepared gold nanostars are analyzed by the FT-IR spectroscopy technique. These results provided insight into the role of biopolymer as both a protecting agent and structure-directing agent. This novel method can overcome previous limitations in controlled synthesis of star-shaped gold nanoparticles such as surfactant use and complex implementation. Besides, the gold nanostars stabilized by chitosan could be a potential material in many applications in the field of biomedical medicine.

Thiolated Gd(III) Chelate Coated Gold Nanoparticles: Synthesis, Characterization, X-Ray CT and MRI Relaxivity Studies

2013 ◽  
Vol 754 ◽  
pp. 121-130 ◽  
Author(s):  
M. Nasiruzzaman Shaikh
Keyword(s):  
Gold Nanoparticles ◽  
Analytical Techniques ◽  
Spherical Shape ◽  
Nanoparticle Surface ◽  
Transmission Electron ◽  
Icp Ms ◽  
Average Size ◽  
Very High ◽  
Ct And Mri

Gadolinium complex of 2-aminothiophenol conjugated DTPA (DTPA=diethylenetriamine N,N,N',N",N" pentacetic acid) bis (amide) has been synthesized and characterized by various analytical techniques such as elemental analysis (EA), NMR, FAB-MS, IR, UV etc. This thiolated GdL (where L is a conjugate of DTPA and 2-aminothiophenol) has been anchored on the gold nanoparticles surfaces through thiols functionalites. These gold nanoparticles (AuNPs) have been synthesized by the reduction of gold tetrachloride (HAuCl4) using sodium citrate as reducing agent. The surface functionalization has been performed by the replacement of citrate coat on the gold nanoparticle surface with thiolated Gd-chelate, Au@GdL. The Au@GdL has been analyzed by XRD, transmission electron microscope (HRTEM), UV, ICP-MS etc. The average size of nanoparticles is about 22 nm with a uniform spherical shape. A very high number of GdL has been loaded on nanoparticle surface reaching up to 7.9x103 of Gd (III)- chelates per nanoparticle and they demonstrate very high r1 relaxivity and the r1 relaxivity per [G is much higher than the Gd (III)-chelate alone. The bimodality has also been tested using in-vitro x-ray computed tomography (x-ray CT). These nanoparticles (GNPs) are very stable and homogeneously dispersed in aqueous solution.

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