No abstract

No abstract

The development of tumor-associated, stimuli-driven, turn-on near-infrared (NIR) fluorophores requires urgent attention because of their potential in selective and precise tumor diagnosis. Herein, we describe a NIR fluorescent probe (CyA-cRGD) comprised of a fluorescence reporting unit (a cyanine dye) linked with a GSH-responsive unit (nitroazo aryl ether group) and a tumor-targeting unit (cRGD). The NIR fluorescence of CyA-cRGD with sensitive and selective response to GSH can act as a direct off-on signal reporter for GSH monitoring. Notably, CyA-cRGD possesses improved biocompatibility compared with CyA, which is highly desirable for in vivo fluorescence tracking of cancer. Confocal fluorescence imaging confirmed the tumor-targeting capability and GSH detection ability of CyA-cRGD in tumor cells, normal cells, and coincubated tumor /normal cells and in the three-dimensional multicellular tumor spheroid. Furthermore, it was validated that CyA-cRGD could detect tumor precisely in GSH and integrin αβ high-expressed tumor-bearing mouse models. Importantly, it was confirmed that CyA-cRGD possessed high efficiency for early-stage tumor imaging in mouse models with tumor cells implanted within 72 h. This method provided significant advances toward more in-depth understanding and exploration of tumor imaging, which may potentially be applied for clinical early tumor diagnosis.

No abstract

The radical suppression of the photodarkening effect and laser performance deterioration via H 2 loading were demonstrated in high-power Yb-doped fiber (YDF) amplifiers. The photodarkening loss at equilibrium was 114.4 dB/m at 702 nm in the pristine fiber, while it vanished in the H 2 -loaded fiber. To obtain a deeper understanding of the impact of photodarkening on laser properties, the evolution of the mode instability threshold and output power in fiber amplifiers was investigated. After pumping for 300 min, the mode instability threshold of the pristine fiber dropped from 770 to 612 W, and the periodic fluctuation of the output power became intense, finally reaching 100 W. To address the detrimental effects originating from photodarkening, H 2 loading was applied in contrast experiments. The output power remained stable, and no sign of mode instability was observed in the H 2 -loaded fiber. Moreover, the transmittance at 638 nm confirmed the absence of the photodarkening effect. The results pave the way for the further development of high-power fiber lasers.