Gold Bulletin最新文献

Chloroalkanes have richer structures and cheaper costs than iodide/brominated compounds, while rarely used as electrophilic reagents for constructing C(sp³)–C(sp³) bonds due to their low reduction potential and strong bond dissociation energy. Recently, a new catalytic strategy involving dinuclear gold complexes has overcome this limitation. The photoinduced gold-catalyzed mode initiated the C(sp³)–Cl electrophilic activation, lead to the divergent conversion of chloroalkanes as chloroalkyl, alkyl cation and carbene equivalent precursor of carbon chain propagation, and involved a novel mechanism of inner-sphere SET process between dinuclear gold complex catalyst and chloroalkane.

Etching solutions of spent printed circuit boards contain a small amount of valuable metals like Au(III) and Pd(II). In order to meet the increasing demand for gold and palladium, it is necessary to recover these metals from the etching solutions. In this work, solvent extraction experiments were done to separate Au(III) from the synthetic hydrochloric acid solutions containing Pd(II), Cu(II), and Ni(II). Single Cyanex 272 and TBP and their mixture were employed to investigate the selective extraction of Au(III) from other metal ions in the HCl concentration range from 1 to 9 M. Single Cyanex 272 and the mixture of Cyanex 272 and TBP successfully separated Au(III) from the solution, while a small amount of Pd(II), Cu(II) and Ni(II) were co-extracted with Au(III) by TBP. The mixture of Cyanex 272 and TBP showed synergism for the extraction of Au(III). The dependence of Au(III) extraction on the mole fraction of TBP in the mixture was pronounced when HCl concentration was 1 and 3 M. The Au(III) loaded into the mixture was completely stripped by low concentration of thiourea and sodium thiosulfate. Pure gold metal was recovered from the thiourea stripping solution by chemical reduction with ascorbic acid. Complete reduction of Au(III) was possible at 80 °C for 30 min when the molar ratio of ascorbic acid to Au(III) was 20.

Cancer was the world’s second major cause of death. Several treatments were available, including chemotherapy, radiotherapy, immunotherapy, and surgery. However, they are restricted due to their risk to normal cells, their ability to destroy the immune system, and conferring increased risk of secondary cancer development. Nanotechnology was extensively researched and used in cancer treatment because nanoparticles could play an essential role in drug delivery. Furthermore, nanoparticle drug delivery systems have been shown to help overcome cancer-related drug resistance. Gold nanoparticles have unique physical, chemical, and biological properties, making them suitable candidates for non-toxic drug carriers. Because of their nanorange size, surface modifications of gold nanoparticles could improve their stability, minimize nanoparticle aggregation, and enhance attachment to anti-cancer agents and target cells, further increasing their ability to penetrate cell membranes and reduce toxicity. This review aims to discuss the current research in targeting drug delivery for anti-cancer agents using gold nanoparticles. By conducting a literature search through the PubMed and Scopus database up to April 2022 using the term gold nanoparticles, targeted drug delivery, chemotherapy, gene therapy, and cancer, this review summarized report on the implementation of gold nanoparticles for targeted drug-delivery systems for cancer therapeutics. The targeting ligands included folic acid, aptamers, hyaluronic acid, glutathione, peptides, and antibodies. According to the findings of studies, implementing gold nanoparticles as nanocarriers significantly improves drug delivery of anti-cancer agents to cancer cells without affecting other untargeted cells. Enhanced cell uptake, increase in drug toxicity, inhibition of tumor growth, and selective drug target are also reported to be the advantages of gold nanoparticle-based targeted drug delivery carriers.

Protein oligomerization contributes to Alzheimer’s disease development (AD). A nanoparticle that can speed up the oligomerization of proteins is generally considered harmful. Gold nanoparticles (AuNPs) have been reported to be making headway in biological platforms, but they may also have the capacity to stimulate protein oligomerization. Our goal herein was to investigate the neurotoxicity and oligomerization of amyloid-β-1-42 (Aβ_1-42) in the presence of AuNPs. The precipitation approach was used to create AuNPs, which were then analyzed using transmission electron microscopy (TEM), ThT, Congo red, and CD spectroscopy. The results demonstrated that the 50-nm-sized fabricated AuNPs guided acceleration in Aβ_1-42. In addition, cytotoxicity studies on PC 12 cells showed that Aβ_1-42 with AuNPs were less toxic than untreated oligomers Aβ_1-42 in terms of inducing cell death, oxidative apoptosis, stress, and membrane leakage. In conclusion, our investigation sheds light on how AuNPs stimulate the development of cytotoxic oligomers by binding to proteins in Alzheimer’s disease.

In this study, carbon quantum dots (CQDs) were first synthesized using a hydrothermal method, and then, Au@SiO₂ core-shell nanomaterials were synthesized using layer-by-layer assembly. CQDs were adsorbed on the surface of Au@SiO₂ nanoparticles through self-assembly to form Au@SiO₂/CQDs nanocomposite materials. Transmission electron microscopy and X-ray diffraction were used to characterize the size, shape, element composition, and structure of nanocomposites; ultraviolet-visible absorption spectroscopy and fluorescence spectroscopy were used to analyze the optical properties of nanocomposites. The results show that Au@SiO₂/CQD nanomaterials have a core-shell structure with good morphology and exhibit excellent luminescence characteristics. The electrochemical performance of nanocomposites was characterized using electrochemical means, and a hydrogen peroxide sensor was constructed for the sensitive detection of hydrogen peroxide, thus realizing the rapid and sensitive detection of hydrogen peroxide at levels as low as 0.2 mM. The electrode GCE modified with Au@SiO₂/CQDs exhibits good selectivity and stability in the detection of hydrogen peroxide.

This study encompasses the synthesis of gold nanoparticles (GNPs) captured on nanofibrous vinyl brushes (NVBs) using sepiolite nanoclay as a matrix. The diameter of GNPs was found to be 2–8 nm investigated by a particle-size analyzer. Due to the high surface reactivity, GNPs are more susceptible to agglomeration which reduces their efficacy as catalyst. A suitable support could be employed to arrest the discrete gold particles on its surface. The distinct textural morphology of sepiolite allows it to be a promising choice as support. Silanol groups on the surface of sepiolite nanofibers were consumed to graft vinyl brushes using hydrolyzed vinyl triethoxy silane. This grafting was characterized by FT-IR spectroscopy. Morphological studies of developed nanocomposites (AuNVBs) were conducted by TEM and FESEM revealing evidently the incorporation of well-distributed GNPs. XRD diffractograms have validated the connectivity of GNPs on NVBs surface. GNPs immobilized on the surface of NVBs are commendable candidates as catalyst to enhance the reaction rate for the conversion of 4- nitrophenol to 4- aminophenol.

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Conventional techniques for microbial detection are time-consuming, expensive, and unsuitable. The use of nanoparticles is a valuable technique for the detection of bacterial as well as viral DNA. Gold nanoparticles (gold NPs) have been used as a promising detector for rapid and low-cost identification of microbes with high sensitivity. In this study, gold nanoparticles-probes were used to identify Pseudomonas aeruginosa and Acinetobacter baumannii genomic DNA. Thiol-functionalized probes were attached to gold NPs. Hybridization of the probe with the amplified product of Oprl and glta genes resulted in accumulation of gold nanoparticles in a cross-linked manner, caused a color change of the reaction mixture, which indicated the presence of Pseudomonas aeruginosa and Acinetobacter baumannii in the sample. To study the sensitivity, the polymerase chain reaction product with different bacteria was used, and results were compared. The gold nanoparticle-based colorimetric assay can be used as a direct and rapid method with high sensitivity for specific identification of these pathogens in clinical and food samples.

Abstract

Abstract

The high enhancement activity of litchi-like gold nanoparticles (Au NPs) is prepared in deep eutectic solvent (DES), and the prepared Au NPs as SERS active substrate exhibits excellent sensitivity when rhodamine 6G (R6G) is used as a probe molecule for detection. The enhancement factor (EF) is calculated to be about 1.8 × 10¹², and the minimum detected concentration is outstanding in R6G aqueous solution at 10⁻¹² M. In addition, the microtrace determination of penicillin G sodium (PG) in camel milk powder produced in Xinjiang was successfully achieved by using the prepared Au NPs. This work provides an environmentally friendly, simple, and rapid method to prepare efficient and sensitive surface-enhanced Raman scattering (SERS) materials. Meanwhile, it also uncovers a new possibility for the development of various nanoparticles with SERS prepared using DES as reactive solutions.

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