The development of efficient multifunctional nanoprobes for tumour imaging has become a great challenge. Herein, we report for the first time the synthesis of folic acid (FA)-conjugated glutathione (GSH)-capped gold nanoclusters (Au NCs) for dual mode fluorescence/X-ray computed tomography imaging of gastric cancer. Water-soluble GSH-capped Au NCs were synthesized by using tetrabutylammonium borohydride (TBAB) as the reducing agent, and was characterized by transmission electron microscopy, UV-vis absorption spectroscopy, fluorescence spectroscopy, and X-ray photoelectron spectroscopy. The AuNCs@GSH showed excellent photoluminescence properties and negligible cytotoxicity at a concentration as high as 200 mg mL À1 . Folic acid was covalently anchored to the AuNCs@GSH; the nanoprobe showed highly selective targeting of the gastric cancer MGC-803 cells revealed by laser scanning confocal microscopy (LSCM). Hematoxylin and eosin (HE) staining results showed that AuNCs@GSH displayed no toxicity to important organs. In conclusion, the FA-conjugated AuNCs@GSH nanoprobe can be used for gastric cancer fluorescence imaging and X-ray computed tomography (CT) imaging. Therefore, the applications of AuNCs@GSH could be extended and bring more benefits to nanotechnology as an ideal biomedical platform.
It is essential to develop a simple synthetic strategy to improve the quality of multifunctional contrast agents for cancer diagnosis. Herein, we report a time-saving method for gadolinium (Gd) ions-mediated self-assembly of gold nanoclusters (GNCs) into monodisperse spherical nanoparticles (GNCNs) under mild conditions. The monodisperse, regular and colloidal stable GNCNs were formed via selectively inducing electrostatic interactions between negatively-charged carboxylic groups of gold nanoclusters and trivalent cations of gadolinium in aqueous solution. In this way, the Gd ions were chelated into GNCNs without the use of molecular gadolinium chelates. With the co-existence of GNCs and Gd ions, the formed GNCNs exhibit significant luminescence intensity enhancement for near-infrared fluorescence (NIRF) imaging, high X-ray attenuation for computed tomography (CT) imaging and reasonable r1 relaxivity for magnetic resonance (MR) imaging. The excellent biocompatibility of the GNCNs was proved both in vitro and in vivo. Meanwhile, the GNCNs also possess unique NIRF/CT/MR imaging ability in A549 tumor-bearing mice. In a nutshell, the simple and safe GNCNs hold great potential for tumor multi-modality clinical diagnosis.
The development of modular strategies for programming self-assembled supramolecular architectures with distinct structural and functional features is of immense scientific interest. We reported on the intrinsic antibacterial capability of anionic amphiphilic gold nanoclusters (GNCs) capped by para-mercaptobenzoic acid, which was closely related to the protonation level of terminal carboxylate groups. By using of the metal−ligand coordination-driven and solvent evaporation-induced self-assembly, we constructed GNCs-based mixed-metal metal−organic network (MM-MON) films on titanium disks as antibacterial nanocoatings. Taking the reasonable utilization of tetravalent metal ions M 4+ (Ti, Zr, Hf; hard Lewis acid) and bactericidal divalent metal ions M 2+ (Cu, Zn; borderline acid) co-incorporated metal−carboxylate coordination bonds, the MM-MON films exhibited superior stability due to the robust M 4+ −O bonds and M 2+ releasing behavior resulting from the labile M 2+ −O coordinating. Together, the MM-MON films integrated the bacteria-responsive character of GNCs, exceptional chemical stability, and greatly enhanced antibacterial activity, ultimately killing adherent bacteria and initiating a self-defensive function. In a rat model for subcutaneous implant-associated infection, the MM-MON nanocoating showed an approximately 2 and 1 log lower multidrugresistant Staphylococcus aureus implant and tissue colonization, respectively. The generalizable modular strategy of the GNC− metal networks is amenable to facilitate the functionalization of metal surfaces for combating implant-associated infections.
Metal ion-induced co-assembly of GNCs and proteins into monodisperse nanoassemblies and the proposed mechanism of the nanoassemblies in cytosolic protein delivery.
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