Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1, Canada.
J Mater Chem B. 2022 Aug 31;10(34):6496-6506. doi: 10.1039/d2tb01252a.
Fluorescence imaging of living cells is key to better understanding cellular morphology and biological processes. Water-dispersible nanoparticles exhibiting thermally activated delayed fluorescence (TADF) have recently emerged as useful probes for time-resolved fluorescence imaging (TRFI), circumventing interference from biological autofluorescence. Many existing approaches, however, require TADF dyes with specific structural features, precluding many high-performance TADF materials from being used in this application. Here, we describe the synthesis of two TADF emitters based on the rigid and strongly electron-withdrawing dibenzo[]dipyrido[3,2-:2'-3'-]phenazine-12-yl (BPPZ) motif, and demonstrate two parallel approaches for the encapsulation of these fluorophores to yield water-dispersible nanoparticles suitable for TRFI. First, fluorescent polymer dots (Pdots) were formed by dye encapsulation within cell-penetrating amphiphilic copolymers. Glassy organic nanoparticles (g-Odots) were also prepared, giving nanoparticles with higher photoluminescence quantum yields and improved colour purity. Both approaches yielded nanoparticles suitable for imaging, with reasonable uptake and cytotoxicity on the timescale of standard imaging experiments using human cervical (HeLa) and liver (HepG2) cancer cell lines. This work demonstrates two flexible strategies for preparing water-dispersible TADF nanoparticles for TRFI, both of which should be readily adaptable to nearly any existing hydrophobic TADF dye.
荧光成像技术在细胞生物学领域有着广泛的应用，它可以帮助科学家更好地理解细胞形态和生物过程。水相分散的热致延迟荧光（TADF）纳米粒子在时间分辨荧光成像（TRFI）中具有重要应用，因为它们可以避免生物自发荧光的干扰。然而，许多现有的方法需要具有特定结构特征的 TADF 染料，这使得许多高性能 TADF 材料无法应用于该领域。本研究基于刚性且强吸电子的二苯并[]二吡啶并[3,2-:2',3'-]吩嗪-12-基（BPPZ）基元，合成了两种 TADF 荧光团，并描述了两种封装这些荧光团的方法，以制备适用于 TRFI 的水相分散纳米粒子。首先，通过将荧光染料包封在穿透细胞膜的两亲性共聚物中，形成了荧光聚合物点（Pdots）。此外，还制备了玻璃状有机纳米粒子（g-Odots），其具有更高的荧光量子产率和更好的颜色纯度。这两种方法都得到了适用于成像的纳米粒子，并且在标准成像实验的时间尺度内，用人宫颈癌细胞（HeLa）和肝癌细胞（HepG2）进行实验，都具有合理的摄取量和细胞毒性。本工作为 TADF 纳米粒子的制备提供了两种灵活的策略，这两种策略都应该可以很容易地适用于几乎任何现有的疏水性 TADF 染料。
