Gold Bulletin最新文献

In this study, amphoteric hydroxyethyl starch/p([2(acryloyloxy)ethyl]trimethylammonium chloride-co-itaconic acid (HES/p(AETAC-co-IA) hydrogels containing both cationic and anionic groups in their structure were synthesized by the redox polymerization method. The synthesized hydrogels were modified with gold nanoparticles, and nanocomposite hydrogels were obtained. The characterizations of the nanocomposite HES/p(AETAC-co-IA)@Au hydrogels prepared for biomedical applications were carried out by SEM, TEM, FT-IR, TGA, and XRD techniques and swelling tests in simulated biological environments. Hydrogels designed as drug carrier cargo materials were loaded with sodium diclofenac (NaDcF) and ibuprofen drugs, and their release properties were studied. The release mechanisms and release kinetics of the two drugs were studied. The release kinetics determined for the drug NaDcF is consistent with the Higuchi model, while the release kinetics determined for ibuprofen is consistent with the first-order model. In addition, the antibacterial and antifungal properties of the hydrogels were tested. It was found that the HES/p(AETAC-co-IA)@Au hydrogel was effective against gram-positive Staphylococcus aureus, gram-negative Pseudomonas aeruginosa, and the fungal species Candida albicans.

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.

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.

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.

Over the past decade, the use of gold complex for photocatalyzed transformations has gained great attention. Within a number of photocatalzed reactions, the mode of energy transfer (EnT) is gradually disclosed, which opens a creative window for gold chemistry. This highlight covers several recent achievements of gold photocatalysis involving EnT process.

The transitioning of nanotechnology from laboratory to industrial-scale manufacturing poses various challenges in nanoparticle realization. From this perspective, beside the conventional synthetic procedure, based on the seed-mediated growth approach, a reshaping thermal strategy has been investigated to improve the control on gold nanorods aspect ratio, with the aim to point out a potential and encouraging way to better manage the scalability and reproducibility of nanoparticles. For this purpose, nanorods covered with CTAB and nanorods enclosed within a silica shell of tuned thickness have been synthesized and submitted to a post-thermal treatment at various temperatures, up to 300 °C for CTAB recovered gold nanorods (AuNR@CTAB), and up to 500 °C for silica-shell embedded gold nanorods (AuNR@SiO₂). For AuNR@CTAB, through accurate temperature control, the longitudinal plasmonic band can be moved very close to the transversal one upon slight reduction of their length. Instead, for AuNR@SiO₂, owing to the fully inorganic shell, a higher temperature of treatment can be reached leading to the possibility of reshaping the nanorods into spheres without the observation of any by-products.

Au(I)/Au(III) redox catalysis, also known as redox gold catalysis, has evolved as a new technique in the past decade, opening up possibilities for the cross-coupling and 1,2-difunctioalization reactions of C–C multiple bonds that were previously inaccessible with gold(I) or gold(III) catalysis. However, the enantioselective Au(I)/Au(III) redox catalysis was missing until recently. The research group of Patil and Shi independently developed new hemilabile chiral (P,N)-ligands to achieve enantioselective redox gold catalysis for the first time.

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