scholarly journals Retention of Activity by Antibodies Immobilized on Gold Nanoparticles of Different Sizes: Fluorometric Method of Determination and Comparative Evaluation

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3117
Author(s):  
Dmitriy V. Sotnikov ◽  
Nadezhda A. Byzova ◽  
Anatoly V. Zherdev ◽  
Boris B. Dzantiev
Keyword(s):  
Gold Nanoparticles ◽  
Average Diameter ◽  
Measurement Procedure ◽  
Antigen Binding ◽  
Reactive Protein ◽  
Gold Salts ◽  
Tryptophan Residues ◽  
Analytical Reagents ◽  
Citrate Reduction ◽  
Sequential Measurements

Antibody–nanoparticle conjugates are widely used analytical reagents. An informative parameter reflecting the conjugates’ properties is the number of antibodies per nanoparticle that retain their antigen-binding ability. Estimation of this parameter is characterized by a lack of simple, reproducible methods. The proposed method is based on the registration of fluorescence of tryptophan residues contained in proteins and combines sequential measurements of first the immobilized antibody number and then the bound protein antigen number. Requirements for the measurement procedure have been determined to ensure reliable and accurate results. Using the developed technique, preparations of spherical gold nanoparticles obtained by the most common method of citrate reduction of gold salts (the Turkevich–Frens method) and varying in average diameter from 15 to 55 nm have been characterized. It was shown that the number of antibodies (immunoglobulins G) bound by one nanoparticle ranged from 30 to 194 during adsorptive unoriented monolayer immobilization. C-reactive protein was considered as the model antigen. The percentage of antibody valences that retained their antigen-binding properties in the conjugate increased from 17 to 34% with an increase in the diameter of gold nanoparticles. The proposed method and the results of the study provide tools to assess the capabilities of the preparations of gold nanoparticles and their conjugates as well as the expediency of seeking the best techniques for various practical purposes.

ANTIBODY CONJUGATES WITH GOLD NANOPARTICLES AS A COMPONENT OF IMMUNOCHROMATOGRAPHIC DIAGNOSTICUMS: THE INFLUENCE OF SYNTHESIS CONDITIONS ON THE COMPOSITION AND REACTIVITY

2020 ◽  
pp. 180-181
Author(s):  
N. Byzova ◽  
A. Zherdev ◽  
B. Dzantiev
Keyword(s):  
Gold Nanoparticles ◽  
Immunochromatographic Test ◽  
C Reactive Protein ◽  
Synthesis Conditions ◽  
Reactive Protein ◽  
Test Systems ◽  
Antibody Conjugates ◽  
Analytical Reagents ◽  
D Dimer

A series of preparations of gold nanoparticles with diameters from 13 to 60 nm and their conjugates with antibodies (murine immunoglobulins of class G) of different composition were obtained. The composition of the conjugates and the amount of antibodies that retain their reactivity in an immobilized form are characterized. Using the example of immunochromatographic test systems for the detection of D-dimer and C-reactive protein, the effectiveness of conjugates as analytical reagents is compared.

scholarly journals Facile Green, Room-Temperature Synthesis of Gold Nanoparticles Using Combretum erythrophyllum Leaf Extract: Antibacterial and Cell Viability Studies against Normal and Cancerous Cells

Antibiotics ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 893
Author(s):  
Olufunto T. Fanoro ◽  
Sundararajan Parani ◽  
Rodney Maluleke ◽  
Thabang C. Lebepe ◽  
Jose R. Varghese ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Cell Viability ◽  
Leaf Extract ◽  
Room Temperature ◽  
Klebsiella Oxytoca ◽  
Cost Effective ◽  
Average Diameter ◽  
Antibacterial Activities ◽  
Inhibition Concentration ◽  
First Time

We herein report a facile, green, cost-effective, plant-mediated synthesis of gold nanoparticles (AuNPs) for the first time using Combretum erythrophyllum (CE) plant leaves. The synthesis was conducted at room temperature using CE leaf extract serving as a reducing and capping agent. The as-synthesized AuNPs were found to be crystalline, well dispersed, and spherical in shape with an average diameter of 13.20 nm and an excellent stability of over 60 days. The AuNPs showed broad-spectrum antibacterial activities against both pathogenic Gram-positive (Staphylococcus epidermidis (ATCC14990), Staphylococcus aureus (ATCC 25923), Mycobacterium smegmatis (MC 215)) and Gram-negative bacteria (Proteus mirabilis (ATCC 7002), Escherichia coli (ATCC 25922), Klebsiella pneumoniae (ATCC 13822), Klebsiella oxytoca (ATCC 8724)), with a minimum inhibition concentration of 62.5 µg/mL. In addition, the as-synthesized AuNPs were highly stable with exceptional cell viability towards normal cells (BHK- 21) and cancerous cancer cell lines (cervical and lung cancer).

Effect of Gold Nanoparticles Size on Detection of Methylphosphonic Acid Hydrolysis Product of Nerve Agent

2021 ◽  
Vol 25 (7) ◽  
pp. 1-7
Author(s):  
Fellyzra Elvya Pojol ◽  
Buong Woei Chieng ◽  
Keat Khim Ong ◽  
Rashid Jahwarhar Izuan Abd ◽  
Mohd Junaedy Osman ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Inverse Method ◽  
Direct Method ◽  
Hydrolysis Product ◽  
Spherical Shape ◽  
Methylphosphonic Acid ◽  
Visible Spectroscopy ◽  
Transmission Electron ◽  
Citrate Reduction ◽  
Chloride Trihydrate

Citrate reduction of gold (III) chloride trihydrate (HAuCl4) is commonly used method to synthesise citrate-capped gold nanoparticles (cit-AuNPs). In this study, the sequence of reagents addition was modified (“inverse” method) to synthesise smaller size of cit-AuNPs than the standard Turkevich method (“direct” method). Ultraviolet-visible spectroscopy (UV-vis) and field emission transmission electron microscopy (FETEM) confirmed the formation of cit-AuNPs. The cit-AuNPs synthesized using “inverse” method are smaller in size (14.0 ± 3.03 nm) with uniform spherical shape compared to “direct” method (23.5 ± 7.52 nm). Smaller particles size of cit-AuNPs provide higher efficiency and sensitivity for detection of methylphosphonic acid (MPA) via colorimetric incorporated with image processing with a linear range from 2.5 to 12.5 mM and a low detection limit of 6.28 mM at shorter detection period (24 to 30 s).

Development of Gold Nanoparticle Radiotracers for Investigating Multiphase System in Process Industries

2012 ◽  
Vol 545 ◽  
pp. 105-110 ◽  
Author(s):  
Mohd Amirul Syafiq Mohd Yunos ◽  
Siti Aslina Hussain ◽  
Jaafar Abdullah ◽  
Engku Mohd Fahmi Engku Chik ◽  
Noraishah Othman ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Nuclear Reactor ◽  
Gamma Ray ◽  
Sol Gel ◽  
Target Material ◽  
Multiphase System ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Process Industries ◽  
Citrate Reduction

This paper describes the development of colloidal Au-SiO2 with core-shell structure nanoparticle radioactive tracers by neutron activation in nuclear reactor that produce Au-198 (T1/2=2.7 d) emitting gamma ray of 412 keV. Using conventional citrate-reduction method, gold nanoparticles were prepared from its corresponding metal salts in aqueous solution then coated with uniform shells of amorphous silica via a sol-gel reaction. The citrate-reduction-based method provides gold nanoparticles with higher concentration and narrow size distribution. By using transmission electron microscopy (TEM), the resultant of particle size and silica coatings could be varied from tens to several hundred of nanometers by controlling the catalyzer and precipitation time. Au-SiO2 core-shell nanostructure is good to prevent the particles from getting agglomerated resulting in a big mass. In addition, silica surface offer very good chances that make the hydrophobic and hydrophilic behavior on the gold nanoparticles. EDXRF spectrum has proven that Au-SiO2 core-shell nanoparticles sample consists purely of a gold and silica particles. This target material of radiotracer application used to investigate multiphase system in process industries without disturbing the system operation.

scholarly journals Exploration of the Antimicrobial and Catalytic Properties of Gold Nanoparticles Greenly Synthesized by Cryptolepis buchanani Roem. and Schult Extract

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Kamonpan Wongyai ◽  
Phitchayapak Wintachai ◽  
Rasimate Maungchang ◽  
Parawee Rattanakit
Keyword(s):  
Staphylococcus Aureus ◽  
Gold Nanoparticles ◽  
Analytical Techniques ◽  
Average Diameter ◽  
Face Centered Cubic ◽  
Tem Analysis ◽  
X Ray ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Face Centered

A green, simple, and rapid synthesis of gold nanoparticles using plant extract, Cryptolepis buchanani Roem. and Schult, and their applications are first described in this paper. The formation of gold nanoparticles was visually observed by the appearance of a ruby red color, which was further indicated by an absorption peak at 530 nm in UV-Vis spectroscopy. Optimization of reaction parameters for the gold nanoparticles was also investigated. Various analytical techniques were employed as part of the process of characterizing the resulting gold nanoparticles. Fourier transform infrared (FTIR) analysis revealed that the phenol compounds present in the extract were responsible for gold(III) reduction and stabilization of gold nanoparticles. Transmission electron microscopy (TEM) analysis showed that the gold nanoparticles were spherical in shape with an average diameter of 11 nm. Powder X-ray diffraction (XRD) pattern indicated that the green synthesis approach produced highly crystalline, face-centered cubic gold nanoparticles. Energy-dispersive X-ray spectroscopy (EDS) measurements confirmed the presence of elemental gold in the prepared nanoparticles. The negative zeta potential value of gold nanoparticles was found to be -30.28 mV. The green synthesized gold nanoparticles expressed effective antibacterial activity against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, and Acinetobacter baumannii and exhibited an excellent catalytic property in terms of its reduction ability of methylene blue.

Fabrication and In-Situ Thermal Reduction of Gold Nanofibers

2020 ◽  
Vol 12 (8) ◽  
pp. 1109-1115
Author(s):  
Xiaojiao Yang ◽  
Jun Li ◽  
Ying Liu
Keyword(s):  
Thermal Analysis ◽  
Gold Nanoparticles ◽  
Fourier Transform ◽  
Average Diameter ◽  
Thermal Reduction ◽  
Gold Content ◽  
Gold Salt ◽  
One Dimensional ◽  
Nanoelectronic Devices

One-dimensional gold nanofibers are good candidates for next generation nanoelectronic devices. Here, gold nanofibers were synthesized via electrospinning with subsequent in-situ thermal reduction. The thermal behavior of the precursor nanofibers was investigated by thermogravimetric/differential thermal analysis and fourier transform infrared. The polymer parts are decomposed and removed step by step, meanwhile, gold salt is decomposed and in-situ reduced to form gold nanoparticles in air without any reducing agent or gas due to its strong oxidation ability. The effects of gold content, polymers type (PVP, PVA, PAN), calcination atmospheres (Air, H2, H2/Ar) and temperatures (200 °C to 500 °C) on the morphology and structures of gold nanofibers were characterized by XRD, SEM, and TEM. The results shows that PVP is the optimal polymer with the gold content of 6:1 (PVP:Au) to fabricate the continuous gold nanofibers with good morphology and structures. The final gold nanofibers with average diameter of 60 nm and several hundred micrometers long, were fabricated after calcined at 500 °C in air for 2 hours. It was composed of gold nanoparticles that ranged from 5 to 30 nm.

scholarly journals Photoregulation of Gold Nanoparticles Stabilized in a Diacetylenic Nanocapsule

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Saowalak Somjid ◽  
Apiwat Chompoosor ◽  
Somdej Kanokmedhakul ◽  
Saowapak Teerasong
Keyword(s):  
Gold Nanoparticles ◽  
Uv Irradiation ◽  
Irradiation Time ◽  
Spherical Shape ◽  
Average Diameter ◽  
Drug Carriers ◽  
Hydrophobic Core ◽  
Triggered Release ◽  
Hydrophobic Molecule ◽  
Positively Charged Gold Nanoparticle

The results of releasing a drug in a burst are unpredictable and one of the inherent drawbacks of using nanocarriers. Here, photoresponsive cationic gold nanoparticles to stabilize diacetylenic nanocapsules enabling photoregulated release of payloads are reported. The fabrication of these nanocapsules relied on an electrostatic interaction of a negatively charged diacetylenic core and a positively charged gold nanoparticle shell. Gold nanoparticles with photoresponsive ligands on their surfaces act as both hydrophobic core stabilizers and gatekeepers of the nanocapsules, while their polydiacetylene cores serve as hydrophobic drug carriers that can be tuned using UV irradiation. The morphology of nanocapsules was analyzed using TEM and dynamic light scattering. The resultant nanocapsules had a spherical shape with an average diameter of 152.9 ± 6.7 nm. Upon UV irradiation, the nanocapsules lost their integrity and an encapsulated model compound was released through diffusion. The release of a hydrophobic molecule was irradiation time dependent and thereby controllable. This light-triggered release provides an alternative strategy for controlled drug delivery.

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