Gold Chloride Research Articles

Retro is the new modern: Contemporary application of gold impregnation staining on brain cryosections for digital image analysis

Background and purpose: Since the times of Golgi and Cajal, impregnation with gold or silver has been used to visualize microscopic details of the nervous tissue. Although immunohistochemistry has largely replaced impregnation techniques, they are still used, and there is a growing interest in combining them with modern image analysis methods for quantitative studies in neuroscience. The aim of this research was to modify the gold chloride impregnation method published by Schmued to improve consistency of staining, to be adequate for digital image analysis. Materials and methods: Brains of 8 six-month-old female Wistar rats were fixed in 4% PFA, cryoprotected in sucrose and flash‑frozen in liquid nitrogen. Neighboring sets of coronal sections were chosen for gold impregnation, Nissl staining and MAP2 immunohistochemistry. Whole-slide images and images of specific regions were taken for analysis. Results: Myelinated fibers were stained dark reddish to brown on goldstained sections, and other tissue was yellowish, which gave an excellent contrast for digital image analysis. Gold staining was consistent in all regions, and no major artifacts were noticed. When compared to Nissl and MAP2, only myelinated structures were stained with gold impregnation. Conclusions: Modified gold impregnation method is an alternative that’s on par with traditional myelin staining methods. The new, modified gold impregnation method gives a consistent and reproducible staining suitable for digital image analysis. It can be useful in morphometric evaluation of nervous tissue and investigation of neuropathological changes in nervous tissue, especially for quantitative studies.

An electrochemical sensor for sub-attomolar determination of aluminum ion with an ultra-wide response range

In this work, an electrochemical sensor was developed for ultra-sensitive determination of aluminum ion (Al3+) using poly(3-aminophenylboronic acid)-gold nanoparticles (PAPBA-AuNPs) modified electrode. The proposed PAPBA-AuNPs modified electrode was prepared by two steps including electrodeposition of gold chloride hydrate and electropolymerization of 3-aminophenylboronic acid. The peak current for PAPBA reduction was recorded by square-wave voltammetry and employed for electrochemical determination of Al3+ based on the coordination reaction between them. With the increasing concentration of Al3+, the peak current for PAPBA reduction diminished. Under the optimized conditions, the proposed electrochemical sensor exhibited a wide response range of 0.10 aM to 10.00 μM and a low limit of detection of 0.019 aM, which is much superior to those of conventional methods. Moreover, this electrochemical sensor was successfully used for Al3+ detection in tap water and instant noodle samples.

Cesium lead iodide-decorated two-dimensional titanium dioxide/reduced graphene oxide nanofiber composites as photoanodes for inorganic perovskite solar cells

In this study, we developed photoanode materials based on inorganic cesium lead iodide (CsPbI3)-decorated two-dimensional titanium dioxide-reduced graphene oxide nanofibers (TiO2/rGO NFs22TiO2/rGO NFs - titanium dioxide-reduced graphene oxide nanofibers.) for perovskite solar cells (PSCs). CsPbI3 was prepared by a two-step solution process and TiO2/rGO NFs were prepared using the electrospinning method. The influence of the as-fabricated TiO2 NFs, TiO2/rGO NFs, and CsPbI3 perovskite on their optical, surface, and morphological properties were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy, ultraviolet–visible–near-infrared spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and atomic force microscopy analyses. XRD analysis of the TiO2 NFs, TiO2/rGO NFs, and CsPbI3 perovskite showed a crystalline nature with cubic and anatase crystal faces. The surface morphology of the TiO2 NFs, TiO2/rGO NFs, and CsPbI3 perovskite appeared as a beat-free fiber with a polycrystalline nature. The chemical oxidative states and electronic structures of the electrospun TiO2/rGO NFs were determined by X-ray photoelectron spectroscopy analysis. PSCs device were assembled with TiO2 NFs, TiO2/rGO NFs as photoanode, 2,2′,7,7′-Tetrakis(N,N-di-P-methoxyphenylamine)− 9,9′-spirobifluorene (Spiro–OMeTAD) as hole transport materials, sputtered gold chloride as back electrode (counter electrode). In addition, the CsPbI3 perovskite coated on the electrospun TiO2 and TiO2/rGO NF photoanodes exhibited electrical conductivities of 1.352 × 10−3 and 1.650 × 10−3 S cm−1. Finally, power conversion efficiency of TiO2/rGO NFs (6.38 %) was achieved, which was significantly higher than that of conventional TiO2 NFs (5.54 %)-based devices.

Fluorescent gold clusters for specific detection of SARS-CoV-2 nucleoprotein via fluorescence and electrochemical method

The promising fluorescent nature and functional properties of gold nanoclusters (AuNCs) enable their use as efficient sensor probes in various fields, particularly in healthcare diagnostics. Together with the effective fluorescence property, AuNCs also possess efficient electrocatalytic activity toward biosensing, thereby featuring the dual-functional (fluorescent and electrochemical) immunoprobe for sensing SARS-CoV-2 nucleoprotein. Density functional theory (DFT) calculations were carried out to assess the electronic structure arrangement of gold (III) chloride and bovine serum albumin (BSA) interactions with gold for efficient formation of Au clusters. Structural studies of coupled AuNCs show that antibodies with active sites for antigen binding are well conjugated on the surface of the gold nanoclusters. X-ray photoelectron and ultraviolet photoelectron spectral studies exhibited that the progression of the work function and ionization energy of nucleocapsid antibody conjugated AuNCs support antigen detection. The bio-affinitive nature of the AuNCs advances the mending of antibodies on their surface so as to increase the binding with epitopes of SARS-CoV-2 nucleoprotein. Antibody conjugated AuNCs based dual sensing system displayed an effective linear response with the lowest detection limit of about 20 pM and exhibited high responsiveness toward nucleoprotein detection. Thus, the dual practical sensing platform constructed from gold nanocluster-derived nanostructures offers new knowledge for additional examinations of COVID-19 detection.

Double pseudo-polymeric complexes of [Au(S2CNR2)2][TlCl4], R2 = (CH2)5, (CH2)6: preparation, structural organization, and thermal behavior (low-temperature reduction and crystallization of gold)

The capability of thallium(I) alkylenedithiocarbamates to bind gold(III) from solutions in 2 M HCl was studied. Double complexes of [Au{S2CN(CH2)5}2][TlCl4] and [Au{S2CN(CH2)6}2][TlCl4] were preparatively isolated as individual forms of gold(III) binding into the solid phase. In the crystalline state, the ionic structural units of the complexes are combined together due to the secondary Au···S, Tl···S and S···Cl bonds that results in complicated supramolecular architectures. Thermal behavior of compounds was studied using the simultaneous thermal analysis technique; both reduced elemental gold and thallium(I) chloride were identified as the final thermolysis products.

(Invited) Electroluminescence from Single-Walled Carbon Nanotubes with Quantum Defects

Individual single-walled carbon nanotubes with covalent sidewall defects have emerged as a new class of photon sources whose photoluminescence spectra can be tailored by the carbon nanotube chirality and the attached functional group/molecule. Here we present electroluminescence spectroscopy data from single-tube devices based on (7,5) carbon nanotubes, functionalized with dichlorobenzene molecules, and wired to graphene electrodes. We observe electrically generated, defect-induced emissions that are controllable by electrostatic gating and strongly red-shifted compared to emissions from pristine nanotubes. The defect-induced emissions are assigned to excitonic and trionic recombination processes by correlating electroluminescence excitation maps with electrical transport and photoluminescence data. At cryogenic conditions additional, gate-dependent emission lines appear which are assigned to phonon-assisted hot-exciton electroluminescence from quasi-levels. Similar results were obtained with functionalized (6,5) nanotubes. We also compare functionalized (7,5) electroluminescence data with photoluminescence of pristine and functionalized (7,5) nanotubes redox-doped using gold(III) chloride solution. This work shows that electroluminescence excitation is selective toward neutral defect-state configurations with the lowest transition energy, which in combination with gate-control over neutral versus charged defect-state emission leads to high spectral purity.Reference: Min-Ken Li et al., ACS Nano 2022 (doi: 10.1021/acsnano.2c03083) Figure 1

Green Synthesis of Mesquite-Gum-Stabilized Gold Nanoparticles for Biomedical Applications: Physicochemical Properties and Biocompatibility Assessment.

Using cytotoxic reducing and stabilizing agents in the synthesis of gold nanoparticles (AuNPs) limits their use in biomedical applications. One strategy to overcome this problem is using "green" synthesis methodologies using polysaccharides. In the present study, we propose a green methodology for synthetizing AuNPs with mesquite gum (MG) as a reducing agent and steric stabilizer in Gold(III) chloride trihydrate aqueous solutions to obtain biocompatible nanoparticles that can be used for biomedical applications. Through this method, AuNPs can be produced without using elevated temperatures or pressures. For synthetizing gold nanoparticles coated with mesquite gum (AuNPs@MG), Gold(III) chloride trihydrate was used as a precursor, and mesquite gum was used as a stabilizing and reducing agent. The AuNPs obtained were characterized using UV-Vis spectroscopy, dynamic light scattering, transmission electron microscopy, scanning transmission electron microscopy, and FT-IR spectroscopy. The stability in biological media (phosphate buffer solution), cytotoxicity (MTT assay, hematoxylin, and eosin staining), and hemocompatibility (Hemolysis assay) were measured at different concentrations and exposure times. The results showed the successful synthesis of AuNPs@MG with sizes ranging from 3 to 30 nm and a zeta potential of -31 mV. The AuNPs@MG showed good colloidal stability in PBS (pH 7.4) for up to 24 h. Finally, cytotoxicity assays showed no changes in cell metabolism or cell morphology. These results suggest that these gold nanoparticles have potential biomedical applications because of their low cytotoxicity and hemotoxicity and improved stability at a physiological pH.

Recovery Study of Gold Nanoparticle Markers from Lateral Flow Immunoassays.

Lateral flow immunoassays (LFIAs) are a simple diagnostic device used to detect targeted analytes. Wasted and unused rapid antigen lateral flow immunoassays represent mass waste that needs to be broken down and recycled into new material components. The aim of this study was to recover gold nanoparticles that are used as markers in lateral flow immunoassays. For this purpose, a dissolution process with aqua regia was utilised, where gold nanoparticles were released from the lateral flow immunoassay conjugate pads. The obtained solution was then concentrated further with gold chloride salt (HAuCl4) so that it could be used for the synthesis of new gold nanoparticles in the process of ultrasonic spray pyrolysis (USP). Various characterisation methods including scanning electron microscopy, transmission electron microscopy, ultraviolet-visible spectroscopy and optical emission spectrometry with inductively coupled plasma were used during this study. The results of this study showed that the recovery of gold nanoparticles from lateral flow immunoassays is possible, and the newly synthesised gold nanoparticles represent the possibility for incorporation into new products.

Synthesis and Coordination Behavior of 9,10-Diarsatriptycene

AbstractHerein, 9,10-diheterotriptycenes (DHTs) containing heavy pnictogens (Pn, Pn = As, Sb, and Bi) are synthesized without using the dangerous chemicals used in conventional synthetic methods: tert-butyllithium, organomercury reagents, or trichloroarsine. In particular, 9,10-diarsatriptycene is obtained in relatively high yield and is stable under oxidation and coordination reactions. Additionally, the gold chloride complex 9,10-diarsatriptycene forms a one-dimensional supramolecular polymer constructed through coordination and aurophilic interactions.

Pierre Figuier

Pierre Oscar Figuier (1759-1817), a French pharmacist whose main contribution was the discovery of using animal charcoal for bleaching inorganic and organic substances. Figuier also carried substantial work on the chemistry of gold, the synthesis of many of its compounds, particularly a triple salt of gold chloride and sodium chloride. He determined the composition of purple thistle and chickpeas.

Synthesis and spectroscopic investigations of Au(III) seleno-organic complexes

ABSTRACT. Heterocyclic pyridazine continues to attract great interest, mainly arising from a large variety of interesting pharmacological activities, herbicides, insecticides, and fungicides. On the other hand, the current interest in selenium-containing heterocycles is a result of their chemical properties and biological activities. In addition to the many recent publications dealing with the pharmacological potential of a selenium compound, new active formulations are an attractive target for chemical research. 2-((3-cyano-4,6-dimethylpyridin-2-yl)selanyl) acetic acid (pyd-Se), 2-((4-cyano-5,6-diphenylpyridazin-3-yl)selanyl)acetic acid (pydz-Se) and 2-((4,6-dimethyl quinolin-2-yl)selanyl)acetic acid (quin-Se) reacts with gold(III) chloride to produce metal ion complexes of specific composition. These synthesized complexes were characterized by elemental analyses, molar conductivity, FTIR, 1H NMR and transmission electron microscopy (TEM) investigations. The complexes were found to have the formulas [Au(pyd-Se)2]Cl, [Au(pydz-Se)2]Cl and Au(quin-Se)2]Cl, respectively.
 
 KEY WORDS: Au(III), Organoselenium, Complexation, FTIR, 1H NMR, TEM
 Bull. Chem. Soc. Ethiop. 2023, 37(5), 1141-1150. 
 DOI: https://dx.doi.org/10.4314/bcse.v37i5.7

Topographical Analysis of Pacinian Corpuscle in the Pulp of Human Cadaver Finger Tip Pulp: A Pilot Cadaver Study.

Background: The human hand is a specialised organ for fine motion and sensation and has a relatively large representation in the homunculus. The pathway of sensation starts from information sent by mechanoreceptors in the hand. This study reports the topography of the Pacinian corpuscle in the fingertips of a human cadaver. Methods: All 10 digits from both hands of a fresh-frozen cadaver were examined. Glabrous skin distal to the distal interphalangeal joint was harvested superficial to the periosteum including fat and subcutaneous tissue. The glabrous skin were divided into 10 sections that included five distal and five proximal sections. Modified gold chloride staining was performed. Sectioned specimens were observed under a light microscope and the density of Pacinian corpuscles was determined in each segment. The density of the corpuscles was compared between the radial/ulnar and proximal/distal segments and also between digits from the right hand versus those from the left hand. Results: Pacinian corpuscles were observed only in the subcutaneous tissue. There was no significant difference in density of the corpuscles between the distal and proximal segments or between the right and left hands. There was a statistically significant greater density of Pacinian corpuscles on the radial segments of all digits except the thumb. Conclusions: There is a greater density of Pacinian corpuscles on the radial side of the human fingertip in all digits except the thumb.

Development of a method to diagnose endometrial cancer based on the AuNRs-AntiVimentin optical probe.

Endometrial cancer is one of the common gynecological malignancies, and its incidence has been increasing year by year in recent years, raising higher requirements for its rapid diagnosis. In this article, gold nanorods (AuNRs) with localized surface plasmon resonance properties (LSPR) has used to prepare AuNRs-antibody to waveform protein (AuNRs-AntiVimentin) optical probes, and a new method has been constructed that could rapidly detect and identify endometrial cancer tissue sections by polarized light microscopy. AuNRs were prepared by seed growth method using gold chloride as raw material, and the morphology of AuNRs and the optical characteristics of AuNRs-AntiVimentin has characterized by transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), and zeta potential; immunohistochemistry (IHC) and AuNRs-AntiVimentin optical probes have used to detect clinical endometrial cancer, respectively. The AuNRs-AntiVimentin optical probe has been used to detect endometrial cancer tissue sections and found to have good bio-specificity, with no significant difference in the detection of AuNRs-AntiVimentin compared with conventional IHC techniques (p > .05). An optical probe generated by coupling AuNRs with Vimentin antibodies has been obtained to detect and identify endometrial cancer with simple operation and comparable effect to conventional IHC, providing a new method and idea for the rapid detection of endometrial cancer.

Green Synthesis of Au-doped SnO 2 Nanoparticles Using Teucrium Polium Plant Extract for the Evaluation of Their Physicochemical and Antibacterial Properties

Background & Objective: The biological production of nanoparticles (NPs) is a technique that has garnered a lot of interest because it is inexpensive, straightforward, and friendly to the natural environment. This study explores the green synthesis of Au-doped SnO 2 NPs using Teucrium polium plant extract and evaluates their antimicrobial properties in comparison with two commonly used antibiotics.
 Materials & Methods: Initially, an extract of Teucrium polium was made using water, and then it was combined with solutions of tin (II) chloride dehydrate [SnCl 2 .2H 2 O] and gold (III) chloride trihydrate [HAuCl 4 .3H 2 O]. The crystal structure was studied using X-ray diffraction (XRD). The form, structure, and grain size of the NPs were analyzed using scanning electron microscope (SEM) and transmission electron microscope (TEM). The synthesized NPs were tested for their antibacterial properties.
 Results: The XRD and EDS analyses revealed that the SnO 2 : Au phase formed an average crystallite size of 22 nm and an Au dopant content of around 2%. The SEM and TEM investigations demonstrated that the NPs were formed in a regular and nanoscale manner, with diameters ranging from 25 to 30 nm. MIC and MBC of SnO 2 : Au NPs against the studied bacteria (S.aureus ATCC 43300, P.aeruginosa PAO1) were reported 9.6±0.13- 9.6±0.07 μg/mL and 25.9±11.5- 32.5±11.2 μg/mL.
 Conclusion: Green-synthesized NPs exhibit significant antimicrobial activity against both Gram-positive and Gram-negative bacteria, even at low concentrations. The NPs effectively eliminate bacteria and prevent biofilm formation.

Efficiency enhancement of perovskite-sensitized solar cell based on electrospun titania nanofibers coated in organic-inorganic hybrid metal trihalide nanocrystals

In this work, we have developed highly efficient, flexible, and thermally stable photoanode materials for perovskite-sensitized solar cells (PSCs). Methylammonium lead iodide (MAPbI3 or CH3NH3PbI3) coated TiO2 nanofibers (TNFs) were prepared by two step process. The cubic crystalline nature of MAPbI3 and the semi-crystalline nature of TNFs were confirmed by X-ray diffraction. The functional groups present in the photoanode materials were identified by Fourier-transform infrared spectroscopy. From UV–visible spectral studies, the absorption maximum of MAPbI3-coated TNFs was observed at 754 nm. High-resolution transmission electron microscopy and scanning electron microscopy images of MAPbI3 and TNFs showed a polycrystalline nature and uniform fiber structures, respectively. The highest electrical conductivity of 5.29 × 10−4 S/cm was achieved by the MAPbI3-coated TNFs photoanode, as measured by electrochemical impedance spectroscopy at room temperature. MAPbI3-coated TNFs, Spiro-OMeTAD, and gold chloride were used as the photoanode, hole transport material, and back electrode, respectively, in a PSC. A PSC constructed with MAPbI3-coated TNFs yielded an efficiency of 13.12%, bettering the 11.48% efficiency of a PSCs constructed from MAPbI3-coated TiO2 nanoparticles.

A ferrocenyl P/NNN hybrid ligand for binding soft/hard metal pairs

The ferrocene-linked P/NNN hybrid ligand 1-diphenylphosphino-1′-dipicolylaminomethylferrocene (FcPN3, 1) was synthesized and bound to a variety of transition metal ions. Treatment of 1 with (tht)AuCl afforded the P-bound gold(I) chloride complex [FcPN3AuCl] (2), treatment with ZnCl2 afforded the N,N,N-bound zinc(II) chloride complex, [FcPN3ZnCl2] (3), and treatment with [Cu(MeCN)4]OTf (OTf– = trifluoromethanesulfonate) afforded the [FcPN3Cu]OTf ion pair (4), where Cu(I) interacts with both the diphenylphosphino and the dipicolylaminomethyl fragments. Complexes 1–4 were characterized by NMR spectroscopy and the molecular structures were determined by X-ray crystallography. The heterometallic complexes [FcPN3(AuCl)(ZnCl2)] (5) and [FcPN3(AuCl)CuOTf] (6) were also synthesized and characterized by 1H and 31P NMR spectroscopy and mass spectrometry.

Collagen Hydrogel Containing Polyethylenimine-Gold Nanoparticles for Drug Release and Enhanced Beating Properties of Engineered Cardiac Tissues.

Cardiac tissue engineering is a promising strategy to prevent heart failure. However, several issues remain unsolved, including efficient electrical coupling and incorporating factors to enhance tissue maturation and vascularization. Herein, a biohybrid hydrogel that enhances beating properties of engineered cardiac tissues and allows drug release concurrently is developed. Gold nanoparticles (AuNPs) with different sizes (18-241 nm) and surface charges (33.9-55.4 mV) are synthesized by reducing gold (III) chloride trihydrate using branched polyethyleneimine (bPEI). These nanoparticles increase gel stiffness from ≈91 to ≈146 kPa, enhance electrical conductivity of collagen hydrogels from ≈40 to 49-68 mS cm-1 , and allow slow and steady release of loaded drugs. Engineered cardiac tissues based on bPEI-AuNP-collagen hydrogels and either primary or human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes show enhanced beating properties. hiPSC-derived cardiomyocytes exhibit more aligned and wider sarcomeres in bPEI-AuNP-collagen hydrogels compared to collagen hydrogels. Furthermore, the presence of bPEI-AuNPs result in advanced electrical coupling evidenced by synchronous and homogenous calcium flux throughout the tissue. RNA-seq analyses are in agreement with these observations. Collectively, this data demonstrate the potential of bPEI-AuNP-collagen hydrogels to improve tissue engineering approaches to prevent heart failure and possibly treat diseases of other electrically sensitive tissues.

Synthesis and luminescence monitoring of iridium(III) complex-functionalized gold nanoparticles and their application for determination of gold(III) ions.

A new method is presented for the one-step synthesis and real-time monitoring of iridium(III) complex-functionalized AuNPs from the precursor gold(III) chloride (AuCl3). The functionalized AuNPs with an average size of 8 - 20nm were obtained by the reduction of Au3+ ions by the alkyne group of iridium(III) complexes, which was accompanied by the anchoring iridium(III) complexes on the surface of the nanoparticles. Meanwhile, the luminescence of the iridium(III) complexes was effectively quenched due to distance-dependent fluorescence quenching by AuNPs, thereby enabling luminescence monitoring of the formation process of the functionalized AuNPs and obtaining scattering information and spectral information in real time. Moreover, this method was applied to the determination of Au3+ ions in buffer with a limit of detection of 0.38μM at 700nm in luminescence mode, while the detection limit for absorbance was 10.04μM. Importantly, the multimodal detection strategy alleviates interference from other metal ions. Furthermore, the iridium(III) alkyne complexes were capable of imaging mitochondrial Au3+ ions in living cells. Taken together, this work opens a new avenue for convenient synthesis and monitoring formation of functionalized AuNPs, and also provides a tool for selective determination of Au3+ ions in solution and in cellulo.

Au Nanoparticles Angered with PVA for Nanocomposites Formation and their Evaluations

This research aims to prepare a nanocolloidal solution of gold and gold capped with PVA by chemical reduction method by sodium tri-citrate as a reducing agent and using gold chloride as a source of gold ions in aqueous solution at room temperature (RT). The prepared materials were diagnosed by scanning electron microscope (SEM) with the elemental composition analysis by energy dispersive X-ray (EDX), as well as the X-ray diffraction (XRD). The obtained results showed that the shape of the prepared particles is spherical with enhanced diameters close to 10 nanometers and with good scattering.

Gold Teflates Revisited: From the Lewis Superacid [Au(OTeF5 )3 ] to the Anion [Au(OTeF5 )4

A new synthetic access to the Lewis acid [Au(OTeF5 )3 ] and the preparation of the related, unprecedented anion [Au(OTeF5 )4 ]- with inorganic or organic cations starting from commercially available and easy-to-handle gold chlorides are presented. In this first extensive study of the Lewis acidity of a transition-metal teflate complex by using different experimental and quantum chemical methods, [Au(OTeF5 )3 ] was classified as a Lewis superacid. The solid-state structure of the triphenylphosphine oxide adduct [Au(OPPh3 )(OTeF5 )3 ] was determined, representing the first structural characterization of an adduct of this highly reactive [Au(OTeF5 )3 ]. Therein, the coordination environment around the gold center slightly deviates from the typical square planar geometry. The [Au(OTeF5 )4 ]- anion shows a similar coordination motif.