Yang Cangjie, Liu Hui, Zhang Yingdan, Xu Zhigang, Wang Xiaochen, Cao Bin, Wang Mingfeng
School of Chemical and Biomedical Engineering, Nanyang Technological University , 62 Nanyang Drive, Singapore 637459.
Biomacromolecules. 2016 May 9;17(5):1673-83. doi: 10.1021/acs.biomac.6b00092. Epub 2016 Apr 4.
This article describes molecular design, synthesis and characterization of colloidal nanoparticles containing polycaprolactone-grafted conjugated polymers that exhibit strong far red/near-infrared (FR/NIR) fluorescence for bioimaging. Specifically, we synthesized two kinds of conjugated polymer bottle brushes (PFTB(out)-g-PCL and PFTB(in)-g-PCL) with different positions of the hexyl groups on the thiophene rings. A synthetic amphiphilic block copolymer PCL-b-POEGMA was employed as surfactants to encapsulate PFTB-g-PCL polymers into colloidal nanoparticles (denoted as "nanoREDs") in aqueous media. The chain length of the PCL side chains in PFTB-g-PCL played a critical role in determining the fluorescence properties in both bulk solid states and the colloidal nanoparticles. Compared to semiconducting polymer dots (Pdots) composed of PFTB(out) without grafted PCL, nanoRED(out) showed at least four times higher fluorescence quantum yield (∼20%) and a broader emission band centered at 635 nm. We further demonstrated the application of this new class of nanoREDs for effective labeling of L929 cells and HeLa cancer cells with good biocompatibility. This strategy of hydrophobic-sheath segregated macromolecular fluorophores is expected to be applicable to a broad range of conjugated polymers with tunable optical properties for applications such as bioimaging.
本文描述了含有聚己内酯接枝共轭聚合物的胶体纳米粒子的分子设计、合成及表征，这些纳米粒子在生物成像中表现出强烈的远红/近红外（FR/NIR）荧光。具体而言，我们合成了两种噻吩环上己基位置不同的共轭聚合物刷（PFTB(out)-g-PCL和PFTB(in)-g-PCL）。使用合成两亲性嵌段共聚物PCL-b-POEGMA作为表面活性剂，将PFTB-g-PCL聚合物在水介质中封装成胶体纳米粒子（记为“nanoREDs”）。PFTB-g-PCL中PCL侧链的链长在决定本体固态和胶体纳米粒子的荧光性质方面起着关键作用。与由未接枝PCL的PFTB(out)组成的半导体聚合物点（Pdots）相比，nanoRED(out)的荧光量子产率至少高出四倍（约20%），且发射带更宽，中心位于635 nm。我们进一步证明了这类新型nanoREDs在有效标记L929细胞和HeLa癌细胞方面的应用，且具有良好的生物相容性。这种疏水鞘隔离大分子荧光团的策略有望应用于广泛的具有可调光学性质的共轭聚合物，用于生物成像等应用。
