Development of Heterodyne Coherent Anti-Stokes Raman Scattering Microscopy for Monitoring Nanoparticle Drug Delivery

目前，由于生物相容性差，95%的潜在新药化合物不能作为药物直接给药，即它们溶解度差，毒性水平不可接受，或在到达感兴趣的部位之前被身体代谢。纳米颗粒药物递送可以通过将化合物包裹在小于千分之一毫米大小的颗粒中来克服这些问题。此外，纳米颗粒可以作为受控药物释放的储存库，并且可以针对体内的特定部位进行定制。众所周知，纳米颗粒给药可以极大地提高药物的有效性，并且已经发现了广泛的应用，不同的给药途径包括口服、静脉注射、经皮和眼。然而，这些纳米颗粒穿越组织、与组织相互作用和修饰组织的机制以及这与改善药物性能的关系仍不清楚。为了开发出剂量更低、副作用更小的未来药物，这些都是需要回答的关键问题。我们回答这些问题的能力很大程度上受到了这样一个事实的阻碍，即目前没有成像方式可以在没有造影剂的帮助下直接可视化这些小颗粒以及周围组织的结构和功能。目前的成像方式是通过外部标签来获得纳米颗粒的图像对比度。此外，使用这些技术，如果不使用活性造影剂替代药物，就不可能检测到纳米颗粒何时以及如何释放药物。我们建议测试一种新型光学显微镜进行无标签测量的可行性。相干反斯托克斯拉曼散射（CARS）显微镜是一种光学技术，其图像对比度来源于样品的内在化学成分。初步的工作表明，CARS可以用于在生物组织背景下对纳米颗粒药物载体进行成像。然而，在充分利用该技术之前，需要对仪器进行修改。在这个提议中，我们计划进行这样的修改，并测试新系统的有效性，以监测纳米颗粒药物向组织和细胞的输送。该项目的成功成果将产生一种工具，可以提供纳米颗粒药物输送基本机制的新信息。这将使药理学家能够合理地设计更有效、更安全、侵入性更小的给药系统。

At present, 95% of all potential new drug compounds cannot be directly administered as a pharmaceutical due to poor biocompatibility, i.e. they have poor solubility, unacceptable levels of toxicity, or become metabolised by the body before reaching the site of interest. Nanoparticle drug delivery can overcome these problems by encapsulating the compounds in particles less than 1 thousandth of a millimetre in size. Moreover, nanoparticles can act as depositories for controlled drug release and can be tailored to actively target specific sites within the body.Nanoparticle drug delivery is known to greatly improve the effectiveness of a pharmaceutical and has found a wide range of applications, with different routes of administration including oral, intravenous, transcutaneous and ocular. However, the mechanisms by which these nanoparticles travel through, interact with, and modify tissues and how this relates to the improved drug performance are still unclear. These are critical questions that need to be answered in order to develop future pharmaceuticals, with lower dosing rates and reduced side effects. Our ability to answers these questions is greatly hindered by that fact that there is currently no imaging modality available to directly visualise such small particles and the structure and function of the surrounding tissue, without the aid of contrast agents. Current imaging modalities derive image contrast of the nanoparticles by means of external labels. Moreover, with these techniques it not possible to detect when and how the nanoparticles release the drug without replacing the drug with an active contrast agent. We propose to test the feasibility of a novel type of optical microscopy for performing label-free measurements.Coherent Anti-Stokes Raman Scattering, or CARS, microscopy is an optical technique in which image contrast is derived from the intrinsic chemical makeup of a sample. Preliminary work has shown that CARS can be used to image nanoparticle drug carriers against a background of biological tissues. However, modifications are required to the instrument before the technique can be fully exploited. In this proposal we plan to make such modifications and test the effectiveness of the new system for monitoring nanoparticle drug delivery to tissues and cells.A successful outcome of this project will produce a tool that can provide new information of the fundamental mechanisms underlying nanoparticle drug delivery. It will allow pharmacologists to rationally design more efficient, safer, and less invasive drug delivery systems.