Near-infrared-II (NIR-II) imaging has shown great potential in medical diagnosis and surgical navigation, but developing safe, photostable, high-brightness molecular probes remains a great challenge. Due to their ultrasmall size resulting in highly efficient renal clearance, gold nanoclusters have shown great clinical potential. In this work, we systematically explored the effect of different ligands on the luminescence and bioactivity of gold nanoclusters. Our results show that gold nanoclusters protected by thioglycolic acid (TGA) and 6-mercaptohexanoic acid (MHA) exhibit the strongest fluorescence, while 3-mercaptopropionic acid (MPA)- and sodium sulfide (Na2S)-protected gold nanoclusters show the weakest NIR-II signal. Further doping showed that the Cd-doped MPA and MHA-protected gold nanoclusters exhibited enhanced fluorescence, but the cysteine (Cys)-, glutathione (GSH)-, and Na2S-protected gold nanoclusters showed fluorescence quenching after doping, indicating significant ligand selectivity. Because of the unique multi-energy structure and the large number of electronic states at the highest occupied molecular orbital energy level, MPA- and MHA-protected gold nanoclusters exhibit high stability and photostability. In addition, gold nanoclusters with different ligands exhibited different selective enzyme-mimicking activities of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT). Imaging in vivo showed that gold nanoclusters could accomplish reliable imaging of cerebral vasculature, hindlimb vessels, and spine as well as monitor renal clearance. The stable nanoclusters allow the time window of imaging to reach 125 min for hindlimb imaging and 270 min for spinal imaging. The gold nanoclusters exhibit a high signal-to-noise ratio of up to 11 for whole-body imaging and show efficient renal clearance and low toxicity at an injected dose of 50 mg/kg.
Wenxi Zhao,Xiaodeng Wang,Xiaoqing Ma,Luchao Yue,Qian Liu,Yonglan Luo,Yang Liu,Abdullah M. Asiri,Xuping Sun
Pseudocapacitive electrochemical Na+-storage has been highlighted as one of the exploitable strategies for overcoming the sluggish diffusion-limited redox kinetics due to the effective structural preservation and fast ion-adsorption/desorption at the surface or quasi-surface of electrode materials. However, exploiting pseudocapacitive hosts with a micro–nano hierarchitecture and further achieving competitive pseudocapacitive contributions are still in their infancy so far. Herein, a yolk–shell NiS2/CuS hollow microspherical architecture with superb kinetically pseudocapacitive features was successfully constructed through an in situ hydrothermal sulfidation and subsequent ion-exchange route using Ni-based bimetallic (NiZn) organic frameworks (NiZn-MOFs) as a template precursor. As expected, the strongly synergistic coupling effect and hollow structural characteristic of the NiS2/CuS heterostructure enabled fast charge transfer and Na+ immigration, as well as the release of the mechanical stress/strain induced by the conversion reaction, and not unexpectedly, the NiS2/CuS electrode afforded extraordinary Na+-storage capability, including a remarkable specific capacity of 410.9 mA h g−1 after 750 cycles at 2.0 A g−1, excellent rate capability, and prolonged cyclability in terms of a remarkable 283.4 mA h g−1 even after 4200 cycles at 20.0 A g−1. More significantly, the kinetic analysis demonstrated that the electrochemical charge storage of the NiS2/CuS electrode manifested considerable pseudocapacitive contributions at all rates (90.0% to 96.9%), distinctly outperforming the previously reported NiS2-/CuS-based anodes. Furthermore, the density functional theoretical calculations suggested a fast Na+-transport kinetics and enhanced antibonding state energy level and Na2S adsorption energy due to the electronic redistribution and lattice distortion in the NiS2/CuS heterointerfaces.
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