been widely used as promising agents for multifunctional blood vessel imaging and tumor imaging. All these agents with well-defined surface chemistry performed good stability and high fluorescence in physiological environment and can be used for NIR-II imaging in vivo. However, due to the large hydrodynamic size, most of inorganic nanoparticles still cannot be excreted rapidly by kidney. The accumulation of these materials in body may induce potential liver toxicity, which prevents their further applications in clinical medicine. Moreover, the organic materials, such as conjugated polymer fluorophores [7] and small molecules, [8] have improved biocompatibility, showing great potential in clinical translation. Nevertheless, the fluorescence quantum yield (QY) of these materials is still far from ideal. Thus, it is desirable to design an NIR-II agent with high QY as well as high efficiency in renal clearance for wide biological and clinical applications. Here, we present a bright Au 25 cluster with the unique cage-like structure that can emit NIR-II fluorescence at 1100-1350 nm by the charge transfer between ligand and gold core. [9] Metal doping further increases fluorescence QY of Au 25 clusters. The time-resolved brain blood flow shows significant differences between healthy and injured brain, which allow us to distinguish the lipopolysaccharides (LPS) induced brain injury and stroke in vivo. Meanwhile, real-time cancer metastasis is monitored by NIR-II imaging. Importantly, the ultrasmall hydrodynamic size of 3.2 nm allows the gold clusters to cross the glomerular filtration and be excreted fast by Near-infrared II (NIR-II) imaging at 1100-1700 nm shows great promise for medical diagnosis related to blood vessels because it possesses deep penetration and high resolution in biological tissue. Unfortunately, currently available NIR-II fluorophores exhibit slow excretion and low brightness, which prevents their potential medical applications. An atomic-precision gold (Au) cluster with 25 gold atoms and 18 peptide ligands is presented. The Au 25 clusters show emission at 1100-1350 nm and the fluorescence quantum yield is significantly increased by metal-atom doping. Bright gold clusters can penetrate deep tissue and can be applied in in vivo brain vessel imaging and tumor metastasis. Time-resolved brain blood-flow imaging shows significant differences between healthy and injured mice with different brain diseases in vivo. High-resolution imaging of cancer metastasis allows for the identification of the primary tumor, blood vessel, and lymphatic metastasis. In addition, gold clusters with NIR-II fluorescence are used to monitor highresolution imaging of kidney at a depth of 0.61 cm, and the quantitative measurement shows 86% of the gold clusters are cleared from body without any acute or long-term toxicity at a dose of 100 mg kg −1 .

Neurotrauma is one of the most serious traumatic injuries, which can induce an excess amount of reactive oxygen and nitrogen species (RONS) around the wound, triggering a series of biochemical responses and neuroinflammation. Traditional antioxidant-based bandages can effectively decrease infection via preventing oxidative stress, but its effectiveness is limited to a short period of time due to the rapid loss of electron-donating ability. Herein, we developed a nanozyme-based bandage using single-atom Pt/CeO2 with a persistent catalytic activity for noninvasive treatment of neurotrauma. Single-atom Pt induced the lattice expansion and preferred distribution on (111) facets of CeO2, enormously increasing the endogenous catalytic activity. Pt/CeO2 showed a 2–10 times higher scavenging activity against RONS as well as 3–10 times higher multienzyme activities compared to CeO2 clusters. The single-atom Pt/CeO2 retained the long-lasting catalytic activity for up to a month without obvious decay due to enhanced electron donation through the Mars–van Krevelen reaction. In vivo studies disclosed that the nanozyme-based bandage at the single-atom level can significantly improve the wound healing of neurotrauma and reduce neuroinflammation.

Catalytic nanomaterials can be used extrinsically to combat diseases associated with a surplus of reactive oxygen species (ROS). Rational design of surface morphologies and appropriate doping can substantially improve the catalytic performances. In this work, a class of hollow polyvinyl pyrrolidone-protected PtPdRh nanocubes with enhanced catalytic activities for in vivo free radical scavenging is proposed. Compared with Pt and PtPd counterparts, ternary PtPdRh nanocubes show remarkable catalytic properties of decomposing H O via enhanced oxygen reduction reactions. Density functional theory calculation indicates that the bond of superoxide anions breaks for the energetically favorable status of oxygen atoms on the surface of PtPdRh. Viability of cells and survival rate of animal models under exposure of high-energy γ radiation are considerably enhanced by 94% and 50% respectively after treatment of PtPdRh nanocubes. The mechanistic investigations on superoxide dismutase (SOD) activity, malondialdehyde amount, and DNA damage repair demonstrate that hollow PtPdRh nanocubes act as catalase, peroxidase, and SOD analogs to efficiently scavenge ROS.

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Based on electrospinning technology, in this study, we fabricated poly(lactic-co-glycolic acid) (PLGA) nanofiber films with high reflectivity and scattering properties. Various films with different thicknesses and fiber diameters were fabricated by changing the electrospinning time and solution concentration, respectively. Detailed optical measurements demonstrate that the film reflectance and scattering ability increase with the thickness, whereas fiber diameter contributes little to both properties. With optimized film thickness and fiber diameter, nanofiber films feature whiteness with a reflectance of 98.8% compared to the BaSO white plate. Furthermore, when deposited on the reflector surface of a remote phosphor-converted light-emitting diode lamp, nanofiber films witness a correlated color temperature deviation decrease from 8880 K to 1407 K and a luminous efficiency improvement of 11.66% at 350 mA. Therefore, the nanofiber films can be applied in lighting systems as a highly reflective coating to improve their light efficacy and quality.