Optical nanosensor for 3D force sensing in intact tissues of live animals

项目摘要 已知物理力以基本方式影响细胞功能。虽然研究日期 追溯到大约100年前，科学兴趣在过去几十年中显著增加。 然而，尽管有广泛的研究，在活体动物中获得精确的力信息， 仍然是一个难以捉摸的任务。目前，绝大多数（如果不是全部的话）力感测研究只有 在培养的细胞中进行。然而，有充分的证据表明， 细胞培养和完整组织之间的差异是机械力和细胞的变化， 细胞粘附因此，精确测量活体动物生物组织内部的力 是推动这一领域发展的迫切需要。 该项目的目标是开发一种新的力传感技术， 感测活体动物中生物组织的3D体积上的力分布。它承诺 通过简单的荧光测量实现高灵敏度的力测量， 在标准共聚焦显微镜中进行。该纳米传感器由金属纳米盘组成， 上转换纳米颗粒和柔性聚合物。上转换纳米粒子由一个 红外线并发射可见荧光。红外激发提供许多益处 包括无背景荧光和高灵敏度。纳米传感器产生 对局部变形高度敏感的荧光信号，能够检测力， 小至1 nN，局部变形小至~1 nm。 最后，我们建立了一个先进的双光子显微镜系统来执行荧光 在活体小鼠中成像。我们已经开发了许多荧光标记的小鼠模型， 解析表皮和毛囊谱系，监测粘附、迁移和增殖 的上皮细胞。该系统将允许我们在生理上测试和微调我们的设计， 相关条件。

PROJECT SUMMARY Physical forces are known to impact cell functions in a fundamental way. While the study dates back some 100 years, the scientific interests have significantly increased in the past decades. However, despite the extensive studies, obtaining precise force information in live animals remains an elusive task. Currently, a vast majority of, if not all, force sensing studies have only been carried out in cultured cells. Yet, it is well-documented that one of the most prominent differences between cell culture and intact tissues is the change of mechanical forces and cell- cell adhesion. Therefore, precise measurements of forces inside biological tissues of live animals are desperately needed to advance the field. The goal of this project is to develop a novel force sensing technique that allows non-invasive sensing of force distribution across 3D volume of biological tissue in a live animal. It promises highly sensitive force measurements with simple fluorescence measurements that can be conducted in a standard confocal microscope. The nanosensor is composed of metal nanodisk, upconversion nanoparticle and flexible polymer. Upconversion nanoparticle is excited by an infrared light and emits visible fluorescence. The infrared excitation provides many benefits including no background fluorescence and high sensitivity. The nanosensor produces fluorescence signal that is highly sensitive to local deformations, enabling detection of force as small as 1 nN and local deformation down to ~1 nm. Finally, we have established a state-of-art two-photon microscope system to perform fluorescence imaging in live mice. We have developed a number of fluorescence tagged mouse models that resolve epidermal and hair follicle lineages and monitor the adhesion, migration and proliferation of epithelial cells. This system will allow us to test and fine-tune our designs in a physiologically relevant condition.