Robust Metallic Actuators Based on Nanoporous Gold Rapidly Dealloyed from Gold–Nickel Precursors

Dealloyed nanoporous gold (np-Au) has applications as oxygen reduction catalysis in Li-air batteries and fuel cells, or as actuators to convert electricity into mechanical energy. However, it faces the challenges of coarsening-induced structure instability, mechanical weakness due to low relative densities, and slow dealloying rates. Here, monolithic np-Au is dealloyed from a single-phase Au₂₅Ni₇₅ solid-solution at a one-order faster dealloying rate, ultra-low residual Ni content, and importantly, one-third more relative density than np-Au dealloyed from conventional Au₂₅Ag₇₅. The small atomic radius and low dealloying potential of the sacrificing element Ni are intrinsically beneficial to fast produce high relative density np-Au, as predicted by a general model for dealloying of binary alloys and validated by experiments. Stable, durable, and reversible actuation of np-Au takes place under cyclic potential triggering in alkaline and acidic electrolytes with negligible coarsening-induced strain-shift. The thermal and mechanical robustness of bulk np-Au is confirmed by two-order slower ligament coarsening rates during annealing at 300 °C and 45 MPa macroscopic yielding strength distinctive from the typical early onset of plastic yielding. This article opens a rich direction to achieve high relative density np-Au which is essential for porous network connectivity, mechanical strength, and nanostructure robustness for electrochemical functionality.     

Maskless Preparation of Spatially-Resolved Plasmonic Nanoparticles on Polydimethylsiloxane via In Situ Fluoride-Assisted Synthesis

Here, a fluoride-assisted route for the controlled in-situ synthesis of metal nanoparticles (NPs) (i.e., AgNPs, AuNPs) on polydimethylsiloxane (PDMS) is reported. The size and coverage of the NPs on the PDMS surface are modulated with time and over space during the synthetic process, leveraging the improved yield (10×) and faster kinetics (100×) of NP formation in the presence of F⁻ ions, compared to fluoride-free approaches. This enables the maskless preparation of both linear and step gradients and patterns of NPs in 1D and 2D on the PDMS surface. As an application in flexible plasmonics/photonics, continuous and step-wise spatial modulations of the plasmonic features of PDMS slabs with 1D and 2D AgNP gradients on the surface are demonstrated. An excellent spatially resolved tuning of key optical parameters, namely, optical density from zero to 5 and extinction ratio up to 100 dB, is achieved with AgNP gradients prepared in AgF solution for 12 minutes; the performance are comparable to those of commercial dielectric/interference filters. When used as a rejection filter in optical fluorescence microscopy, the AgNP-PDMS slabs are able to reject the excitation laser at 405 nm and retain the green fluorescence of microbeads (100 µm) used as test cases.     

Black phosphorous nanosheets–gold nanoparticles–cisplatin for photothermal/photodynamic treatment of oral squamous cell carcinoma

To improve five-year survival rate of oral squamous cell carcinoma (OSCC), the development of a novel composite material of black phosphorus nanosheets (BPNSs) and gold nanoparticles (AuNPs) for tumor treatment was carried out. The purpose of this study is to evaluate the cytostatic effects of BPNSs, AuNPs loaded with cisplatin (CDDP) on human tongue squamous cell carcinoma cells lines (SCC-9), and 7,12-dimethylbenz anthracene induced cheek squamous cell carcinoma was validated in golden hamsters animal models. The results showed that BPNSs could efficiently inhibit the metastasis and growth of OSCC compared with CDDP and AuNPs. And a combination composite of AuNPs–BPNSs loaded with CDDP could more effectively inhibit the metastasis and growth of OSCC, which might be due to the high drug-loading capacity, excellent photothermal properties and the combination of photodynamic and photothermal therapy of BPNSs and AuNPs, as well as the synergistic effects of AuNPs, BPNSs and CDDP.     

Rapid Synthesis and Antiproliferative Properties of Polyazamacrocycle-Based Bi- and Tetra-Gold(I) Phosphine Dithiocarbamate Complexes

A family of bi- and tetrametallic gold(I) phosphine dithiocarbamate complexes were synthesized, starting from cyclam and dimethylcyclam polyazamacrocycles, respectively, along with their monometallic gold(I) chloridophosphine precursors. Their antiproliferative properties were evaluated on two cancer cell lines (A549 and NSCLC-N6-L16). Most of the mono- and bimetallic complexes displayed strong activities and, in particular, one bimetallic derivative showed antiproliferative properties in the low micromolar range. Insights into the structure–activity relationships are given, along with determination of the thioredoxin reductase inhibition potential, two-photon imaging of the fluorescent derivatives, and evaluation of gold uptake.     

陕西省略阳县干河坝金矿地质特征及矿床成因探讨

干河坝金矿床是南秦岭南段勉略康构造混杂岩带内属受岩相和构造双重控制的构造蚀变岩型金矿床。该矿床的矿体集中产于古生界泥盆系金家河岩组金家河千枚岩与乔子沟火山岩的岩性—构造接触带附近，多呈似层状、透镜状。为进一步探讨该矿床成因，通过对矿床成矿地质特征、地球化学背景及硫同位素的系统研究，认为：①该矿床的赋矿层位就是其初始矿源层；②经区域变质变形和多期构造活动，初始矿源层中的成矿物质活化、迁移，在近EW向张性裂隙中充填、沉淀而富集成矿。     

福建某低品位金矿新型浸金剂浸金试验

福建某斑岩型金矿品位低、规模大,金主要以自然金形式存在,可见金的粒度较粗,为高效利用该低品位金矿,开展新型浸金剂金蝉全泥浸出试验和柱浸试验,结果表明：全泥浸出在磨矿细度为-0.074 mm占80%、矿浆浓度25%、加石灰调pH 值11.0左右、初始金蝉浓度为500 mg/L和过程中控制金蝉浓度不小于300 mg/L条件下浸出20 h,金的浸出率为93.43%,金蝉耗量为1.02 kg/t；柱浸在矿石粒度为-30 mm条件下喷淋浸出23天,金累计浸出率和金蝉累计耗量分别为86.54%和1.22 kg/t。     

Self-Assembly of Proteinaceous Shells around Positively Charged Gold Nanomaterials Enhances Colloidal Stability in High-Ionic-Strength Buffers

The enzyme lumazine synthase (LS) has been engineered to self-assemble into hollow-shell structures that encapsulate unnatural cargo proteins through complementary electrostatic interactions. Herein, we show that a negatively supercharged LS variant can also form organic–inorganic hybrids with gold nanomaterials. Simple mixing of LS pentamers with positively charged gold nanocrystals in aqueous buffer spontaneously affords protein-shelled gold cores. The procedure works well with differently sized and shaped gold nanocrystals, and the resulting shelled complexes exhibit dramatically enhanced colloidal stability over a wide range of pH (4.0–10.0) and at high ionic strength (up to 1 m NaCl). They are even stable over days upon dilution in buffer. Self-assembly of engineered LS shells in this way offers an easy and attractive alternative to commonly used ligand-exchange methods for stabilizing inorganic nanomaterials.     

Gold Drugs with {Au(PPh3)}+ Moiety: Advantages and Medicinal Applications

Following the success of Auranofin as an anti-arthritic drug, search for novel gold drugs has afforded a large number of [L−Au(PPh₃)] complexes that exhibit notable salutary effects. Unlike Au(III)-containing species, these gold complexes with {Au(PPh₃)}⁺ moiety are stable in biological media and readily exchange L with S- and Se-containing enzymes or proteins. Such exchange leads to rapid reduction of microbial loads or induction of apoptotic cell death at malignant sites. In many cases the lipophilic {Au(PPh₃)}⁺ moiety delivers a desirable toxic L to the specific cellular target in addition to exhibiting its own beneficial activity. Further research and utilization of this synthon in drug design could lead to novel chemotherapeutics for treatment of drug-resistant pathogens and cancers.     

Metallic Nanoparticle-Enabled Sensing of a Drug-of-Abuse: An Attempt at Forensic Application

γ-Hydroxybutyric acid (GHB) functions as a depressant on the central nerve system and serves as a pharmaceutical agent in the treatment of narcolepsy and alcohol withdraw. In recent years, GHB has been misused as a recreational drug due to its ability to induce euphoric feelings. Moreover, it has gained increasing attention as a popular drug of abuse that is frequently related to drug-facilitated sexual assaults. At the moment, detection methods based on chromatography exhibit extraordinary sensitivity for GHB sensing. However, such techniques require complicated sample treatment prior to analysis. Optical sensors provide an alternative approach for rapid and simple analysis of GHB samples. Unfortunately, currently reported probes are mostly based on hydrogen bonding to recognize GHB, and this raises concerns about, for example, the lack of specificity. In this work, we report a bioinspired strategy for selective sensing of GHB. The method is based on specific enzyme recognition to allow highly selective detection of GHB with minimum interference, even in a complex sample matrix (e. g., simulated urine). In addition, the result can be obtained by either quantitative spectroscopy analysis or colorimetric change observed by the naked-eye, thus demonstrating its potential application in drug screening and forensic analysis.     

Easy access to pharmaceutically relevant heterocycles by catalytic reactions involving α-imino gold carbene intermediates

This review summarizes recent advances in the field of gold-catalyzed synthesis of pharmaceutically relevant aza-heterocycles via in situ generated α-imino gold carbene complexes as intermediates.