与传统的光致发光(PL)不同,在机械激发下实现的机械发光(ML)表现出独特的特性,如高穿透性,空间分辨率,和用于生物成像应用的信号背景比(SBR)。然而,使用有机机械发光材料的生物成像仍然具有挑战性,因为具有短发射波长的ML的穿透深度浅,并且没有合适的机械力来在体内产生ML。为了解决这些问题,本文首次报道了纯有机发光体的超声(US)激发荧光和磷光的实现,其发射波长延伸到红色/NIR区域,美国激发发射的穿透性明显高于PL。因此,可以使用基于机械发光的胶囊设备实现US激发的皮下磷光成像,该胶囊设备的定量强度为9.15±1.32×104ps-1cm-2sr-1,SBR为24。此外,可以使用共轭骨架的填充模式充分调谐US激发的发射,机械发光的偶极取向,以及分子间相互作用的强度和方向。总的来说,本研究创新性地扩展了有机机械发光材料的激发源种类和发射波长,为基于美国激发发射的实际生物应用铺平了道路。
Unlike traditional photoluminescence (PL), mechanoluminescence (ML) achieved under mechanical excitation demonstrates unique characteristics such as high penetrability, spatial resolution, and signal-to-background ratio (SBR) for bioimaging applications. However, bioimaging with organic mechanoluminescent materials remains challenging because of the shallow penetration depth of ML with short emission wavelengths and the absence of a suitable mechanical force to generate ML in vivo. To resolve these issues, the present paper reports the achievement of ultrasound (US)-excited fluorescence and phosphorescence from purely organic luminogens for the first time with emission wavelengths extending to the red/NIR region, with the penetrability of the US-excited emission being considerably higher than that of PL. Consequently, US-excited subcutaneous phosphorescence imaging can be achieved using a mechanoluminescent-luminogen-based capsule device with a quantified intensity of 9.15 ± 1.32 × 104 p s-1 cm-2 sr-1 and an SBR of 24. Moreover, the US-excited emission can be adequately tuned using the packing modes of the conjugated skeletons, dipole orientation of mechanoluminescent luminogens, and strength and direction of intermolecular interactions. Overall, this study innovatively expands the kind of excitation sources and the emission wavelengths of organic mechanoluminescent materials, paving the way for practical biological applications based on US-excited emission.