Gold Bulletin最新文献

Identifying ternary gold alloys by their mere colors appears to be problematic. Surface state induces multiple reflections and creates mixtures of structural colors. Two models stochastic backward raytracing (SBR) and finite asymmetrical dihedral facets (FADF) are explored to compute the color of a given surface state. Assaying gold by its color without a touchstone seems hopeless but using colorimetric microscopy and variable magnification could be a way forward.

Peptide modification enhances the physicochemical properties of peptides by introducing specific chemical groups or structural adjustments, but achieving site-selective modification remains a significant challenge. Recently, the selective functionalization of peptides, particularly through metal catalysis, has attracted growing attention. Gold catalysts, in particular, have emerged as a powerful tool due to their high catalytic efficiency, exceptional stability, and biocompatibility. Gold-catalyzed peptide modifications can improve target specificity, modulate protein–protein interactions, and enable precise control over functional group incorporation. This review focuses on the latest advancements in gold-catalyzed site-selective functionalization of peptides, by providing a detailed overview of these developments, we aim to increase understanding in the field and encourage further exploration of gold-mediated peptide modifications.

Extraction of gold from electronic waste was commonly conducted using aqua regia. Here, we have shown a method to produce chloroauric acid in a salt solution by bipolar AC electrolysis. The developed bipolar AC electrolysis method provides an environment-friendly process to extract gold from electronic waste containing gold without using any strong acids such as aqua regia. 

Cancer is a significant global health issue that requires innovative methods for diagnosis and treatment. Gold nanoparticles (AuNPs) are becoming more popular due to their unique physical and chemical properties, having ability to interact with biological systems without causing harm, and their ease of modification. This paper examines the potential of AuNPs to transform cancer theranostic via the integration of diagnostics and treatment. We explore the use of AuNPs in cancer imaging, specifically examining their ability to enhance contrast in several imaging techniques, enabling the early and accurate detection of tumors. In addition, we discuss the use of AuNP-mediated photothermal therapy (PTT), where AuNPs convert light into heat to selectively destroy cancer cells. In addition, we are exploring the capacity of AuNPs to serve as carriers for drug delivery, enabling the specific delivery of chemotherapeutic agents to tumor sites while reducing the overall negative effects on the body. One of the key advantages of AuNPs emphasized in this review is their ability to integrate therapeutic and imaging characteristics. We analyze the current challenges and propose strategies to improve the delivery and design of AuNPs for more effective cancer theranostic. AuNPs show great potential for personalized and effective cancer treatment since they may connect diagnosis and therapy.

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.