Gold Bulletin最新文献

Despite numerous reports on the successful preparation of organo-dispersible gold nanoparticles (AuNPs), complicated multi-step synthetic procedures and poor colloidal stability are still the main drawbacks. Poly (N,N-dimethylaminoethyl methacrylate) (PDMAEMA) is a polymer which is potent for reducing Au³⁺ to Au(0) with diverse dispersibility in organic solvents. With respect to these advantages, PDMAEMA was employed as both a reducing and stabilizing agent for the direct synthesis of AuNPs in water and some protic and aprotic organic solvents in this study. Notably, there was no need for any extra reducing agent or phase transfer material here. The kinetic of AuNPs formation and the effect of medium type on the size, shape, and dispersibility of AuNPs were studied by using TEM and UV–Vis results. Comprehensive analyses revealed that binding of PDMAEMA onto the gold precursor, established interactions, and conformation of PDMAEMA chains with consequent coverage of AuNPs surface are influential on the nucleation and growth rates, size, shape, dispersibility, and assembly of nanoparticles. This in-situ method will develop the exploitation of organo-dispersible metal nanoparticles, especially in the field of catalysts and sensors.

Acute kidney injury (AKI) is a critical condition characterized by a rapid deterioration in kidney function, frequently resulting in severe complications and elevated mortality rates. Recent advancements in nanomedicine have introduced porphyrin-loaded gold (Au) functionalized polymeric nanodots (P-APNDs) as a promising therapeutic approach for AKI. The formation of P-APNDs was confirmed by analyzing physiochemical parameters such as FTIR, XRD, and TEM which revealed their spherical shape with a smaller size of 10 nm. The P-APND exhibits significant efficacy in alleviating AKI due to its preferential renal accumulation and potent antioxidant capacity. P-APND exhibited exceptional antioxidant properties in effectively scavenging various toxic free radicals, thereby providing efficient cellular protection against oxidative stresses in vitro at HEK 293 cell lines and found that P-APND was effective in treating cisplatin (Cs) induced cell lines. The in vivo analysis was carried out in a Cs-induced mice model. The accumulation of the drug in the kidney for a prolonged time shows the efficiency of the P-APND. The decreased serum creatinine levels and blood urea nitrogen confirm the improvement of kidney injury after the treatment with P-APND. Combining this therapy with comprehensive nursing care could mark a significant advancement in AKI management.

Printed circuit boards (PCBs) contain precious metals like gold and palladium. After pretreatment, PCBs are dissolved with aqua regia to recover precious metals. Reduction and precipitations experiments were done to recover gold metal and palladium(II) compound from PCB etching solutions which contained Au(III), Pd(II), Al(III), Cu(II), Fe(III), Ni(II), Sn(II), and Zn(II). In the first step, Au(III) ions were chemically reduced to gold metal using ascorbic acid without changing the acidity of the solution. The optimal conditions for the reduction were 1.5 for the molar ratio of ascorbic acid to Au(III) at room temperature for 30 min. Then, PdI₂ was recovered from the filtrate by using NaI as a precipitant. The optimal conditions for this precipitation were a NaI/Pd(II) molar ratio of 7 at room temperature for 60 min. The purity of the gold metal and PdI₂ was verified by measuring the composition of the solution after dissolving with aqua regia. A simple process was proposed to recover gold metal and PdI₂ powders with 99.9% purity from the etching solutions of PCBs at room temperature.

This study investigates the optimization of placer gold ore processing using a laboratory-scale Knelson concentrator through response surface methodology (RSM) and Box-Behnken experimental design. Fifteen experiments were conducted to assess the effects of three parameters: solid concentration (wt.%), G force (G), and fluidization water flow rate (l/min), on gold grade and recovery. Statistical analyses using Design Expert 13 revealed significant quadratic regression equations for both gold grade and recovery, with high coefficients of determination. The empirical models demonstrated the intricate relationships between the concentrator parameters and process responses. Interpretation of the equations revealed that increasing the solid concentration positively influenced gold grade and recovery, while higher G force and fluidization water flow rate negatively impacted these parameters. Moreover, synergistic effects were observed between certain parameter pairs, indicating the complex interplay of factors influencing gold concentration and extraction efficiency. The study highlights the importance of understanding the separation mechanisms within the Knelson concentrator, especially in the presence of flaky gold particles alongside spherical particles. Insights gained from this research provide valuable guidance for optimizing placer gold ore processing operations, ultimately enhancing efficiency and sustainability in mineral processing practices.

We describe an environmentally benign method for the synthesis of porous gold by gelation of a hydrophilic polymer bearing metal-coordination units (thiocarbonyl groups, denoted as HPMC) and Au(III) ions. The gelation was performed by dropwise addition of a dispersed aqueous solution of HPMC to an aqueous solution of Au(III) in a test tube. Concentrations of 15 and 20 wt% HPMC provided elongated and fibrous gels. Scanning electron microscopy and transmission electron microscopy analyses of the fibrous gels revealed the formation of porous gels containing Au nanoparticles. Calcination of the polymer parts in the porous gels at 550 °C for 7 h, followed by self-assembly of the remaining Au nanoparticles, provided the golds with micrometer-size pores. Thermogravimetric analysis of the porous golds indicated that its purity was high (96 ~ 99%). Because the metal-coordination unit has soft basic characteristics, it preferentially coordinate to soft acidic noble metal ions such as platinum group metal ions, Ag(I), and so on. Therefore, this method will be applied to synthesis of various porous metals.

Fabrication and optical characterization of evanescent plasmonic fiber sensor for detection of Lead (Pb²⁺) ions in water are described. Glutathione-capped gold nanourchins (GNU-GSH) were immobilized onto fluorinated silicon dioxide (SiO₂) clad using (3-Aminopropyl) triethoxysilane (APTES). At 488 and 638 nm Raman wavelength, a penetration depth of 98 and 128 nm was obtained where the sensing region acts as nanoantenna at far-field for detection of analyte. The absorbance of LSPR decreased by time indicating the binding of Pb²⁺ to GSH ligand. Two types of fiber sensors were prepared using 10 and 30 min of GNU incubation time (i.e., F10 and F30) each irradiated in horizontal and vertical configurations. Dynamic SERS study of GNU-GSH-Pb²⁺ showed that F10 and F30 exhibit a similar non-linear response, where the former reached the maximum intensity faster than the latter one. Fluorescence spectroscopy of GNU-GSH in horizontal configuration indicated the maximum emission wavelength of 633 and 605 nm for F10 and F30, respectively. In the vertical configuration, the wavelengths of 607 and 727 nm were observed, respectively, for F10 and F30. When Pb²⁺ was added, a hyperchromic shift of fluorescence occurred from 652 to 655 nm in 2 min for F10, and the intensity decreased linearly by ≈ 72% in 13 min indicating the gradual binding of Pb⁺² ions to GSH sites. In the case of F30, the emission gradually red-shifted from 551 to 569 nm within 15 min, and the emission reached the maximum at 561 nm after 10 min of interaction.

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.