Cluster for Advanced Macromolecular Design (CAMD), School of Chemistry, University of New South Wales (UNSW Sydney), Sydney NSW 2052, Australia.
Institute for Biomedical Materials & Devices (IBMD), Faculty of Science, University of Technology Sydney, Sydney NSW 2007, Australia.
Biomacromolecules. 2021 Aug 9;22(8):3168-3201. doi: 10.1021/acs.biomac.1c00669. Epub 2021 Jul 25.
The strong upconversion luminescence (UCL) of upconversion nanoparticles (UCNPs) endows the nanoparticles with attractive features for combined imaging and drug delivery. UCNPs convert near-infrared (NIR) light into light of shorter wavelengths such as light in the ultraviolet (UV) and visible regions, which can be used for light-guided drug delivery. Although light-responsive drug delivery systems as such have been known for many years, their application in medicine is limited, as strong UV-light can be damaging to tissue; moreover, UV light will not penetrate deeply into the skin, an issue that UCNPs can now address. However, UCNPs, as obtained after synthesis, are usually hydrophobic and require further surface functionalization to be stable in plasma. Polymers can serve as versatile surface coatings, as they can provide good colloidal stability, prevent the formation of a protein corona, provide a matrix for drugs, and be stimuli-responsive. In this Review, we provide a brief overview of the most recent progress in the synthesis of UCNPs with different shapes/sizes. We will then discuss the purpose of polymer coating for drug delivery before summarizing the strategies to coat UCNPs with various polymers. We will introduce the different polymers that have so far been used to coat UCNPs with the purpose to create a drug delivery system, focusing in detail on light-responsive polymers. To expand the application of UCNPs to allow photothermal therapy or magnetic resonance imaging (MRI) or to simply enhance the loading capacity of drugs, UCNPs were often combined with other materials to generate multifunctional nanoparticles such as carbon-based NPs and nanoMOFs. We then conclude with a discussion on drug loading and release and summarize the current knowledge on the toxicity of these polymer-coated UCNPs.
上转换纳米粒子（UCNPs）的强上转换发光（UCL）赋予了纳米粒子用于组合成像和药物输送的有吸引力的特性。UCNPs 将近红外（NIR）光转换为较短波长的光，如紫外线（UV）和可见光区域的光，可用于光引导药物输送。尽管光响应药物输送系统已经存在多年，但它们在医学中的应用受到限制，因为强 UV 光会对组织造成伤害；此外，UV 光不会深入穿透皮肤，这是 UCNPs 现在可以解决的问题。然而，经过合成获得的 UCNPs 通常是疏水性的，需要进一步进行表面功能化才能在等离子体中稳定。聚合物可以作为通用的表面涂层，因为它们可以提供良好的胶体稳定性、防止形成蛋白质冠、为药物提供基质并具有刺激响应性。在这篇综述中，我们简要概述了具有不同形状/尺寸的 UCNPs 的最新合成进展。然后，我们将讨论聚合物涂层用于药物输送的目的，然后总结用各种聚合物涂覆 UCNPs 的策略。我们将介绍迄今为止用于涂覆 UCNPs 的不同聚合物，以创建药物输送系统，重点详细介绍光响应聚合物。为了扩大 UCNPs 的应用范围，以允许光热疗法或磁共振成像（MRI），或者只是增强药物的载药量，UCNPs 通常与其他材料结合，生成多功能纳米粒子，如基于碳的 NPs 和纳米 MOFs。然后，我们将讨论药物负载和释放，并总结关于这些聚合物涂覆的 UCNPs 的毒性的现有知识。
