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Background: Fibroblast activation protein (FAP), a transmembrane serine protease overexpressed by cancer-associated fibroblasts in the tumor stroma, is an interesting biomarker for targeted radionuclide theranostics. FAP-targeting radiotracers have demonstrated to be superior to [18F]FDG PET/CT in various solid cancers. However, these radiotracers have suboptimal tumor retention for targeted radionuclide therapy (TRT). We aimed to develop a novel FAP-targeting pharmacophore with improved pharmacokinetics by introducing a substitution at the 8-position of (4-quinolinoyl)-glycyl-2-cyanopyrrolidine, which allows for conjugation of a chelator, dye, or other payloads. Results: Here we showed the synthesis of DOTA-conjugated eFAP-6 and sulfo-Cyanine5-conjugated eFAP-7. After chemical characterization, the uptake and specificity of both tracers were determined on FAP-expressing cells. In vitro, [111In]In-eFAP-6 demonstrated a superior affinity and a more rapid, although slightly lower, peak uptake than gold standard [111In]In-FAPI-46. Confocal microscopy demonstrated a quick FAP-mediated internalization of eFAP-7. Studies with HT1080-huFAP xenografted mice confirmed a more rapid uptake of [177Lu]Lu-eFAP-6 vs. [177Lu]Lu-FAPI-46. However, tumor retention at 24 h post injection of [177Lu]Lu-eFAP-6 was lower than that of [177Lu]Lu-FAPI-46, hereby currently limiting its use for TRT. Conclusion: The superior affinity and faster tumor accumulation of eFAP-6 over FAPI-46 makes it a suitable compound for radionuclide imaging. After further optimization, the eFAP series has great potential for various oncological interventions, including fluorescent-guided surgery and effective targeted radionuclide theranostics. [ABSTRACT FROM AUTHOR]

[Objective] This study comprehensively evaluated the drought tolerance of watermelon resources by screening drought tolerant germplasm resources and identifying key drought tolerance indexes at seedling stage to provide support for drought tolerance breeding of watermelon. [Method] Twenty-five watermelon materials were selected for two treatments of drought stress and normal watering in pots at seedling stage. Seven growth indexes including plant height, root length, aboveground fresh weight, underground fresh weight, aboveground dry weight, underground dry weight and root-shoot ratio, and six physiological indexes including chlorophyll content, soluble protein content, proline content, nialondialdehyde con-tent, catalase activity and relative conductivity were measured. Using the methods of membership function, multiple linear regression analysis and cluster analysis, the response differences of watermelon gerniplasm to drought stress were compared, the drought resistance of gerniplasm at seedling stage was evaluated, and the key drought resistance indexes were screened. [Result] Drought stress inhibited the growth and development of watermelon seedlings. Drought stress significantly inhibited shoot fresh mass and root fresh mass of watermelon seedlings, generally reduced plant height, root length, shoot dry mass and root dry mass, and had positive and negative effects on root-shoot ratio. After drought treatment, proline content in watermelon leaves increased significantly, catalase activity increased generally, soluble protein content and relative conductivity in leaves decreased generally, while chlorophyll and nialondialdehyde contents showed differences among germplasms. [Conclusion] The watermelon materials with strong drought resistance at seedling stage including M20, ZTC, M33, M24 and M26, and they can be used for further breeding watermelon resources with drought resistance. Shoot fresh weight, catalase activity, soluble protein content, pro-line content, underground dry weight, and root length could be used as the traits for evaluating drought resistance of watermelon seedlings. [ABSTRACT FROM AUTHOR]

The luminescent film materials sensitive to external stimuli are important to develop new types of optical sensors and switches. Herein we report organic–inorganic hybrid ultrathin films (UTFs) with reversible luminescence response to nitroaromatic explosive compounds by the use of layer-by-layer assembly of optical brightener BBU and Mg–Al-layered double hydroxide (LDH) nanosheets. UV-Visible absorption and fluorescence spectroscopy showed an orderly growth of the BBU/LDH films upon increasing the number of deposition cycle. XRD, AFM and SEM measurements indicated that the films feature periodic layered structure with a period of ca. 2 nm as well as uniform surface morphology. The BBU/LDH UTFs exhibit well-defined one/two-photon polarized photoemission with the anisotropy as high as 0.38. Moreover, the UTFs show a fast, selective and reversible luminescence response to different nitroaromatic explosives with the most significant luminescent red-shift occurring for picric acid; in addition, by combining suitable luminescent building blocks, the films can also be extended to other dual-color luminescence systems, which exhibit changes in both luminescence intensity and ratiometric fluorescence upon interaction with explosives, enlightening that these films can serve as new types of selective solid luminescent sensors towards nitroaromatic compounds. [ABSTRACT FROM AUTHOR]