Gold Bulletin最新文献

A simple, eco-friendly method for the synthesis of gold nanoflowers using a non-proteinogenic amino acid is discussed in the present work. Gold nanostructure with unique morphology was synthesized, with the assistance of ornithine amino acid. Ornithine-stabilised gold nanoflowers were found to be highly sensitive towards mercury ions (Hg²⁺) due to Au–Hg amalgamate formation. Due to amalgamate formation, an evolution in morphology of ornithine-stabilised gold nanoflowers happens which can be monitored by the red shift in surface plasmon resonance. Under optimum conditions, our sensor shows a dynamic response range with a detection limit of 6 nM. This developed nanosensor can be used as Hg²⁺ ion sensor in polluted water/waste water by a one-step assay protocol.

The current study exemplifies the synthesis of novel gold nanoformulations loaded with dioxepine derivative a secondary metabolite from lichen Parmotrema reticulatum utilizing a green approach proving an insight into the impregnation method. The characteristic features of synthesized dioxepine-derived gold NPs (Dd-AuNPs) were analyzed using FT-IR (Fourier Transform Infrared Spectroscopy); it elaborates on the presence of diverse groups with broadband at 3461 cm⁻¹ indicating the presence of the –OH group and the small dip at 2928 cm⁻¹ corresponds to the stretching vibrations of –CH of carbohydrates. The crystallinity of synthesized Dd-AuNPs displayed three distinctive peaks in the 2θ range based on the XRD (X-ray diffraction) pattern. The surface zeta potential of Dd-AuNPs was + 58 mV, which shows the prepared nanoparticle surface has high positive charges and also showed an average hydrodynamic diameter of 661 nm with a peak intensity of 88% using the dynamic light scattering technique. The study elaborates its characterization with SEM (scanning electron microscope) analysis which indicates that AuNPs were dispersed in the solution; as supplementary, the results of HRTEM (high-resolution transmission electron microscopy) were shown at different magnifications along with selected area electron diffraction (SAED) pattern with several morphologies such as spherical, triangular, and hexagonal which particle size ranges from 20 to 30 nm. The synthesized Dd-AuNPs effectively scavenged free radicals in a dose-dependent manner with 21–45% and 12–71% of DPPH (2,2-diphenyl-1-picrylhydrazyl) and FRAP (ferric ion reducing antioxidant power) assay respectively. In addition, in vitro studies exhibited high cytotoxic activity against the human lung cancer cell line (A549) with IC₅₀ value of 12 μg/mL using MTT (3-(4,5-dimethylthiozol-2-yl)-3,5- diphenyl tetrazolium bromide) assay and accompanied by AO/EtBr (acridine orange (AO) and ethidium bromide (EtBr)) and DAPI (4′,6-diamidino-2-phenylindole) staining methods to confirm the apoptosis, nuclear condensation, and fragmentation. Similarly, flow cytometry analysis results provide greater shreds of evidence demonstrating that apoptosis occurred during the S phase, which was further confirmed using caspase assay proving the occurrence of apoptosis. These results highlight the intriguing potential of synthesized Dd-AuNPs as an effective source of bioactive compounds with antioxidant and anticancer abilities, necessitating additional research into their potential therapeutic potential in lung cancer cell lines.

Graphical Abstract

Osteoporosis represents a prevalent disease that involves the degeneration of bone. The development of potent therapies is desired because the current clinical treatments are not able to provide a satisfying therapeutic effect. Recently, gold (Au) nanomaterials and chondroitin sulfate (CS) have been attracted a lot of attention in the field of drug delivery. The purpose of this research was to investigate exactly CS-AuNP function and its positive influences on anti-osteoporosis in ovariectomized (OVX) rats. The outcome of the OVX rats experimental results revealed effective anti-osteoporosis molecular targets of developed CS-AuNP formulation and their influence on the gut microbiota. Importantly, CS-AuNPs significantly improved lipid profiles, bone microstructure, metabolism markers, and bone mineral density. The findings provide more evidence that CS-AuNPs have effective therapeutic potential in anti-osteoporotic treatment by the MAPK signaling pathway.

For targeted delivery in the cancer model, this work intends to construct nanoparticles (NPs) using folate (FA)-gemcitabine (GEM)-loaded polyvinylpyrrolidone (PVP)-gold (Au) nanoparticles (GEM@FA/PVP@Au NPs). By precisely assembling the layer, we could construct gemcitabine-loaded FA-functionalized PVP@Au NPs. Various spectroscopical analyses were used and characterized with GEM@FA/PVP@Au NPs. Using MTT assay, wound migration assays, and morphological staining assays, we investigated the antimigratory and anticancer in vitro effects of NPs. To develop GEM@FA/PVP@Au NPs, gemcitabine (40 µg/mL) and folate conjugation onto PVP@Au NPs were added. The NPs demonstrated an 80% release of gemcitabine at acidic pH after their size and charge were incrementally raised by layer-by-layer assembly. Neither the human submandibular gland (HSG) cells and human oral squamous cell carcinoma (HSC-4) cells showed anticancer activity at the concentrations studied for the NPs. In in vitro studies, they inhibited cell migration and had a high apoptosis ratio. The flow cytometry analysis reveals that fabricated nanoparticles effectively kill cancer cells in both cancer cells. These findings indicate the potential of folate-based tumor targeting using GEM/PVP@Au NPs as a safe and effective method for treating parotid gland cancer tumors.

To make the most of the unique properties of nanomaterials, and to bridge the gap between fundamental and applied research, controlled, green, cheap and energy efficient syntheses of nanoparticles are required. In this respect, room and low temperature surfactant-free colloidal syntheses of nanoparticles obtained in low viscosity and low boiling point solvents, without additives or nature-derived extracts, are promising to develop more active (electro)catalysts. Recently, a room temperature synthesis of surfactant-free gold nanoparticles has been documented (Chem. Mater. 2023, 35, 5, 2173) that requires only water, a base such as NaOH, an alcohol and HAuCl₄. Unfortunately, the syntheses of nanomaterials are often sensitive to multiple parameters and it is well acknowledged that reproducibility is a general challenge in the chemical sciences, where the synthesis of nanomaterials is no exception. Here, we investigate the effect of the water conductivity and solvent grade on the surfactant-free low temperature (ca. 30 °C) synthesis of colloidal gold nanoparticles obtained in alkaline mixtures of ethanol and water. The synthesis can be performed with relatively low-grade ethanol but requires high purity water. The importance of water with low conductivity is also stressed for syntheses where ethylene glycol and glycerol are used as source of reducing agents. The results of this study over 100 samples pave the way to greener, more controlled and scalable syntheses of surfactant-free gold nanomaterials.

To elucidate an antitumor drug exhibiting enhanced activity relative to cisplatin, a novel dinuclear gold(III) complex was synthesized, incorporating 1,5-naphthyridine as a bridging ligand. Subsequently, the newly synthesized complex underwent comprehensive characterization using various techniques to validate its structural attributes. The stability of the complex in both water and PBS buffer was assessed through UV–Vis spectroscopy. DNA binding studies were conducted employing UV–Vis, fluorescence spectroscopy, and viscosity measurements. Competitive studies with ethidium bromide (EB) or 4′-hydroxyethidium (HOE) were performed utilizing fluorescence spectroscopy. The findings indicated that the dinuclear gold(III) complex interacts with calf thymus DNA (CT-DNA) through a groove binding mode. Moreover, the investigated complex exhibited significant binding constants for its interaction with human serum albumin (HSA) and bovine serum albumin (BSA) and interactions in the presence of site markers (eosin Y or ibuprofen). The dinuclear gold(III) complex demonstrated notable cytotoxicity against HCT116 and MDA-MB-231 cancer cell lines at 24 and 72 h post-treatment. Furthermore, the complex displayed selectivity by inducing significantly lower cytotoxic activity in healthy cells than in cancerous ones. In support of its antitumor activity, the complex exhibited proapoptotic effects, as evidenced by increased caspase 9 activity and low percentages of necrosis. Molecular docking simulations were employed to corroborate all experimentally obtained results.

The Heck reaction has been considered a robust method for the cross-coupling reaction of olefins and aryl halides to yield alkenes. However, the most significant requirement is the necessity of electronically biased olefins and the requirement of directing group to control the regioselectivity of the Heck reaction. The research group of Patil and Gandon recently documented the gold-catalyzed Heck reaction, demonstrating the utilization of simple aliphatic alkenes as substrates. This approach does not need electronically biased olefins and offers a distinct regioselectivity when compared to the Heck reaction catalyzed by other transition metal catalysts.

The utilization of engineered gold nanoparticles (GNPs) in biomedical applications is experiencing rapid growth owing to their reactive nature and remarkable flexibility. However, despite these advantages, concerns persist regarding their in vivo biocompatibility and cytotoxicity. This study aimed to assess the toxicity, biodistribution, and excretion pathways of GNPs functionalized with various antibiotics, namely, ciprofloxacin, levofloxacin, cefotaxime, and ceftriaxone, using a mouse model. Following intravenous administration, the nanostructures induced an increase in serum enzyme levels and histological abnormalities in the liver, indicating potential hepatotoxic effects. Analysis of organ distribution revealed accumulation primarily in the liver and spleen, with concentrations gradually decreasing 168-h post-administration. Fecal excretion was identified as the primary route of elimination, with a smaller portion excreted via urine. Among the different nanostructures evaluated, those functionalized with levofloxacin (LEV-NP) exhibited minimal organ toxicity and a high clearance rate. Additionally, LEV-NP, with a size of approximately 12 nm, demonstrated superior drug particle stability and lower red blood cell hemolytic activity compared to other nanostructures.

A simple microextraction method has been developed for the preconcentration of Au(III) and its measurement by an ultraviolet–visible spectrophotometer. Benzalkonium chloride, a cationic surfactant, was used as a complexing agent for the preconcentration of Au(III) in the form of AuCl₄⁻. An ion pair between AuCl₄⁻ and benzalkonium chloride was finely extracted into the 1,2-dichloroethane phase through a simple emulsification process. Parameters affecting the preconcentration of Au(III) were evaluated, including the acidity of the solution, the amount of the cationic reagent, and the effect of interferences. The calibration curve of the method for Au(III) was linear in the range of 0.05–0.80 mg L⁻¹. The detection limit, enrichment factor, and relative standard deviation were 0.01 mg L⁻¹, 40, and 1.9%, respectively. The accuracy of the method was evaluated through addition-recovery tests on real water samples. The results demonstrate that this microextraction method was successfully applied to stream water samples for the preconcentration of Au(III).

The synthesis of gold nanoparticles (AuNPs) by bottom-up methods, such as redox reactions using amino acids and gold salts, has turned out to be a novel method for obtaining nanoparticles due to the reducing properties of these biomolecules and the ability to give the nanoparticle peculiar physicochemical characteristics for its biological application, thus derived from the known structure and amino acids functional groups. In this sense, this work shows the characterization using UV-Vis, DLS, FTIR, XPS, and HRTEM techniques of AuNPs synthesized using sodium borohydride (NaBH₄) as a reducing compound and L-cysteine methyl ester hydrochloride (cysteine precursor) (HSCH₂CH (NH₂) COOCH₃ • HCl) as a stabilizing agent. The above elucidates the reaction mechanisms for the formation of the nanoparticle through these reactions, as well as the stabilizing action and possible reducing potential of cysteine. Likewise, the resulting Cis@AuNP compounds were subjected to a preliminary biological evaluation using cell viability toxicity tests. The Cis@AuNPs showed high colloidal stability in a pH range of 3 to 11, where the L-cysteine methyl ester hydrochloride functional groups strongly influenced the hydrodynamic diameter and zeta potential behavior. Cytotoxicity assays in mouse leukocytes demonstrated the safety of these nanoparticles. These encouraging results open the way to explore the biological application potential of these systems with the perspective of their possible application in vaccinology.