Conjugated Polymer Nanoparticles for Near Infrared Fluorescence Imaging

在这项工作中，我们将生产一种用于高性能临床近红外（NIR）体内成像的荧光纳米颗粒系统，这是一种非常有前途的技术，目前由于使用性能较差的有机染料作为荧光成像剂而受到阻碍。显示出高的组织穿透性，因此可用于非侵入性地可视化体内结构。长期以来，高性能近红外体内成像一直被认为是核成像技术的一种非常有前途的替代方案，因为它具有更高的灵敏度和分辨率，以及取代对患者和临床医生构成风险的放射性示踪材料的使用的明显好处。虽然NIR成像将用于各种诊断应用，但目前认为它特别有希望用于淋巴系统的成像，特别是与其在癌症转移中的作用有关。由于缺乏强而稳定的NIR造影剂，NIR成像目前未用于临床环境。小分子有机染料是可商购的并且已经被研究为NIR造影剂，但是它们的弱荧光发射限制了它们的实际应用。开发、批准和商业化的近红外成像剂与增强性能的有机染料将是一个至关重要的一步，最大限度地发挥潜力的近红外在vivo imaging.In工作中提出的，纳米粒子将合成共轭聚合物，表现出极强的吸收和荧光发射。共轭聚合物纳米颗粒（CPN）已经成为用于体内成像的非常有前途的荧光探针，因为它们表现出优异的光学性质，同时缺乏在其他荧光纳米颗粒如量子点（例如镉）中发现的固有毒性成分。近红外荧光将通过将CPN与近红外染料组合以创建将高能量吸收与有效能量转移耦合以产生强近红外荧光亮度的系统来实现。这些纳米颗粒的关键特征是它们的激发和发射最大值都将在NIR中-这是NIR体内成像的绝对先决条件，并且是迄今为止在CPN中尚未实现的功能。我们开发CPN作为NIR成像剂的策略的第二个定义特征是将广泛的体外和初步的体内安全性测试作为纳米颗粒设计阶段的固有部分（即设计安全性）。这种前瞻性的方法将确保从一开始就选择临床可行的系统进行研究，从而促进项目时间和资金的最大效率。该计划将产生和优化一个高性能，安全的近红外发射纳米粒子系统将分三个阶段完成：1）纳米粒子特性的系统研究2）选择一种纳米颗粒系统用于随后的优化和全面的体外安全性测试; 3）体内性能评估和初步的体内安全性测试。这个项目非常及时，因为全球对CPN的兴趣正在迅速增加。在过去的五年里，KCL的研究人员一直处于这一令人兴奋的研究领域的最前沿，并且已经做出了重大贡献，成为国际上第一批生产共轭聚合物纳米颗粒并将其转移到生物医学应用中的团队之一。这项工作在近红外成像临床应用方面的进一步扩展将加强英国在快速发展的医学工程领域的领先地位。

In this work we will produce a fluorescent nanoparticle system for high performance clinical near infrared (NIR) in vivo imaging, an extremely promising technology that is currently being held back by the use of poorly performing organic dyes as fluorescent imaging agents.NIR light, at wavelengths between 700 and 1000 nm, exhibits high tissue penetration and can therefore be used to non-invasively visualise structures inside the body. High performance NIR in vivo imaging has long been mooted as a highly promising alternative to nuclear imaging techniques, as it exhibits improved sensitivity and resolution, as well the obvious benefit of replacing the use of the radioactive tracer materials which pose a risk to both patients and clinicians. Although NIR imaging will be useful for a variety of diagnostic applications, it is currently considered to be particularly promising for imaging of the lymphatic system, specifically in relation to its role in cancer metastasis. NIR imaging is not currently used in the clinical setting due to a lack of strong and stable NIR contrast agents. Small molecule organic dyes are commercially available and have been investigated as NIR contrast agents, but their weak fluorescence emission limits their practical use. Development, approval and commercialization of NIR imaging agents with enhanced performance over organic dyes will be a vital step towards maximising the potential of NIR in vivo imaging.In the work proposed herein, nanoparticles will be synthesised from conjugated polymers which exhibit extremely strong absorption and fluorescence emission. Conjugated polymer nanoparticles (CPNs) have emerged as highly promising fluorescent probes for in vivo imaging as they exhibit excellent optical properties whilst lacking the intrinsically toxic ingredients found in other fluorescent nanoparticles such as quantum dots (cadmium, for example). NIR fluorescence will be achieved by combining CPNs with NIR-dyes to create a system which couples high energy absorption with efficient energy transfer to produce strong NIR fluorescence brightness. The key feature of these nanoparticles is that both their excitation and emission maxima will be in the NIR - an absolute prerequisite for NIR in vivo imaging, and a functionality that has not been achieved in CPNs to date. A second defining feature of our strategy to develop CPNs as NIR imaging agents is the incorporation of extensive in vitro and preliminary in vivo safety testing as an intrinsic part of the nanoparticle design phase (i.e. Safety-by-Design). This forward-thinking approach will ensure that a clinically viable system is chosen for investigation from the start, thus promoting maximum efficiency of project time and funding. The programme to generate and optimise a high performance, safe NIR-emitting nanoparticle system will be completed in three phases: 1) Systematic investigation of nanoparticle properties (optical, physicochemical and in vitro safety) from selected combinations of conjugated polymers and NIR dyes; 2) Selection of one nanoparticle system for subsequent optimization and comprehensive in vitro safety testing; 3) in vivo performance evaluation and preliminary in vivo safety testing. This project is extremely timely as global interest in CPNs is increasing rapidly. The KCL investigators have been at the forefront of this exciting area of research over the last five years, and have already made a significant contribution by being one of the first groups internationally to produce conjugated polymer nanoparticles and transfer them into biomedical applications. The further expansion of this work towards clinical applications in NIR imaging will strengthen the UK lead in the rapidly evolving sector of medical engineering.