荧光碳量子点:合成、特性及在肿瘤治疗中的应用

A State-of-the-art Review on Fluorescent Carbon Quantum Dots: Fabrication, Characterization and Potential in Cancer Therapy

碳量子点是一种以碳元素为主要成分的新型荧光碳纳米材料。碳量子点是纳米材料的一员,具备纳米材料所共有的表面和界面效应,因而表面非常活跃,易于功能化修饰;纳米材料具有小尺寸效应和量子尺寸效应,使得碳量子点具有优异的荧光性能,荧光量子产率高、稳定性强、光谱可控;另外,碳量子点的水溶性优良,碳元素的构成保证了碳量子点的低细胞毒性和良好的生物相容性,极小的粒径和分子量也有利于其在生物体内的应用。这些突出的性能使得碳量子点在肿瘤体外检测、体内成像、肿瘤靶向载体与治疗等领域中都有重要的应用价值。仅从肿瘤治疗方面而言,碳量子点在许多传统和新兴的肿瘤治疗方法中都有很多深层次的应用。纳米药物载体技术是大部分学者利用碳量子点来改善化学治疗过程最常用的手段。它是将纳米材料作为基本单元,通过物理和化学等手段将药物连接、吸附或者包裹在纳米材料上,利用载体的特殊性能来实现更好的抑癌效果。而碳量子点诸多的优良性能也使其在化学治疗过程中有非常多的应用,包括:(1)改善药物的水溶性,以提升治疗效果;(2)提高药物对病灶处的靶向性,降低对正常细胞的危害;(3)延长药物在人体内的滞留时间;(4)实现药物智能高效释放等。这些复合载药体系具有特异性、靶向性、定量准确、易吸收等特点,可以有效提高治疗效果。此外,碳量子点的光热转化特性、光致发光特性也使得其在光热治疗和光动力治疗等新兴治疗方法中有所应用。光热治疗提高了热疗过程中的安全性和高效性;碳量子点在光动力治疗应用中,可以显著改善光敏剂水溶性差、荧光量子产率低、光源穿透深度不够、癌变组织氧气供应不足等应用难题,为深层肿瘤治疗提供了研究思路。多种方式的协同治疗也可以将治疗效果提升至最大化。本文归纳了碳量子点的合成方法以及新的制备工艺的发展趋势,总结了碳量子点在肿瘤治疗中所具有的优良性能,并着重介绍了碳量子点在光动力治疗、光热治疗和化疗等肿瘤治疗领域中的前沿应用。

Carbon quantum dots(CDs or C-dots)are novel fluorescent nano-materials mainly composed of carbon.As a member of nanomaterials,CDs show the common surface and interface effects,hence the surface of CDs is greatly active and prone to be modified.Thanks to the small size effect and quantum size effect,CDs are also endowed with excellent fluorescence performance,exhibiting high quantum yield,stability and controllable properties.In addition,the excellent water solubility,low cytotoxicity,satisfactory biocompatibility,small particle size and molecular weight are favorable for the application of CDs in vivo.The above mentioned outstanding properties of CDs enable the widespread applications of CDs in diverse fields,including tumor imaging,detection,targeting and therapy.Just from the perspective of tumor therapy,the applications of CDs have deeply penetrated in traditional and emerging approaches already.Taking advantages of CDs,researchers commonly employ nano-drug delivery system to optimize the chemotherapy.It uses nanomaterials as the basic unit,then the drugs are absorbed or encapsulated onto the nano-carriers through physical or chemical connection,and finally to achieve a better anticancer effect by the special properties of nano-carriers.Accordingly,CDs play a significant role in chemotherapy process due to their excellent performance.Specifically speaking,CDs can enhance the therapeutic effect by improving the water solubility of drug,reduce the da-mage of drugs to the normal cells by improving the targeting ability to the lesion,prolong the retention time of the drug,and realize the intelligent and efficient drug release.Furthermore,the characteristic of photothermal conversion and photoluminescence properties of CDs have also paved the way for extensive application of CDs in many emerging therapeutic approaches,such as photothermal therapy and photodynamic therapy.As regard to hyperthermia treatment,CDs can significantly improve the safety and efficiency.In photodynamic therapy,CDs contribute to improve the solubility,quantum yield of photosensitizer,penetration depth of light source and oxygen supply around cancerous tissue.The CDs in multiple treatments can also boost the therapeutic effect to the maximum.In this article,we introduce the synthesis approaches and latest progress in CDs preparation,summarize the excellent properties of CDs in tumor therapy,and put emphasis on frontier application of CDs in cancer therapy including photodynamic therapy,photothermal therapy and chemotherapy.