Ultrasmall dopamine-coated nanogolds: preparation, characteristics, and CT imaging

<p>Water-dispersible ultrasmall nanogolds (WDU AuNPs) and their dopamine-coated nanogolds (WDU AuNPs@DPAs) were prepared by a reduction method with sodium borohydride as a reducing agent and a stabilised agent of 2-mercaptosuccinic acid in aqueous solution. The effects of these nanoparticles on computed tomography (CT) imaging were evaluated. The size distributions and Zeta potential of the nanoparticles were measured with a Malvern size analyser, and nanoparticle morphology was observed by transmission electron microscopy. These characteristics were confirmed by Fourier transform spectroscopy and ultraviolet/visible spectra. It was found that WDU AuNPs@DPAs were 5.4 nm in size with clear core–shell structure. The 3-(4, 5-Dimethyl-2-thiazolyl)-2, 5-diphenyltetrazolium bromide assay results showed that the WDU AuNPs and WDU AuNPs@DPAs were hypotoxic to different cells. The WDU AuNPs@DPAs showed a much longer circulation time and a larger CT attenuation coefficient than iohexol and could be excreted by the kidney and bladder. These nanoparticles showed considerable potential for future application in CT imaging.</p

Insight into a Bentonite-Based Hydrogel for the Conservation of Sandstone-Based Cultural Heritage: In Situ Formation, Reinforcement Mechanism, and High-Durability Evaluation

Conservation of sandstone-based cultural heritage has attracted a great deal of interest. We propose herein a novel protecting strategy, via in situ fabrication of bentonite-based hydrogels (B-H) inside sandstones, where the bentonite-based hydrogels serve as the underlying cement. To create bentonite-based hydrogels with controllable structure, possessing good mechanical and anti-swelling properties, we have optimized forming time, appearance, and viscosity. The hydrogel precursor penetrated into the pores of the sandstone; the hydrogel would then form within 3–5 h. As found by employing a fluorescent tracer, the precursor remained controllably in place without any apparent change in the sandstone morphology. The bentonite-based hydrogels that formed inside the sandstones presented strong hydrogen bonding, coordination, and ionic bonding, as well as strong mechanical interlocking to the sandstone matrix. As a result, the sandstones possessed enhanced mechanical compressive strength and excellent resistance to acid, salt, and freeze–thaw cycles. Our approach provides for a non-destructive, eco-friendly, easy-to-use, and long-term strategy for cultural preservation, one with excellent protection effects

General Strategy for the Preparation of Stable Luminous Nanocomposite Inks Using Chemically Addressable CsPbX₃ Peroskite Nanocrystals

The potential optoelectronic applications of perovskite nanocrystals (NCs) are primarily limited by major material instability arising from the ionic nature of the NC lattice. Herein, we introduce a facile and effective strategy to prepare extremely stable CsPbX₃ NC–polymer composites. NC surfaces are passivated with reactive methacrylic acid (MA) ligands, resulting in the formation of homogeneous nanocubes (abbreviated as MA-NCs) with a size of 14–17 nm and a photoluminescence quantum yield above 80%. The free double bonds on the surface then serve as chemically addressable synthetic handles, enabling UV-induced radical polymerization. Critically, a bromide-rich environment is developed to prevent NC sintering. The composites obtained from copolymerizing MA-NCs with hydrophobic methyl methacrylate and methacrylisobutyl polyhedral oligomeric silsesquioxane monomers exhibit enhanced properties compared to previously reported encapsulated NCs, including higher quantum yields, remarkable chemical stability toward water, and much enhanced thermal stability. The good solubility of the composite in organic solvent further enables its use as a solution-processable luminescent ink, used here for fabrication of white-light-emitting diodes with high luminous efficiency and excellent color-rendering index. The resulting fluorescent and stable NC ink opens the door to potential scalable and robust optoelectronic applications