Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 1H6, Canada.
Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada.
Biomacromolecules. 2020 Jun 8;21(6):2014-2023. doi: 10.1021/acs.biomac.9b01713. Epub 2020 May 4.
Elongated colloidal nanoparticles (NPs) have significant potential for drug delivery and imaging applications in cancer therapy, but progress depends on developing a deeper understanding of how their physicochemical properties affect their interactions with cells and with tumors. Cellulose nanocrystals (CNCs) are biocompatible, rodlike colloids that are broadly surface-functionalizable, making them interesting as modular drug carriers. In this report, we describe the attachment of a statistical copolymer containing oligoethylene glycol methacrylate (OEGMA; ≈ 500 Da) and small amounts of aminopropylmethacrylamide (APMA) to CNCs. Here, the copolymer is designed to serve as a "stealth" corona to minimize protein adsorption, and the amino groups provide functionality for the attachment of diagnostic or therapeutic moieties. The corona polymer with a terminal azide group was synthesized by atom transfer radical polymerization using -butyloxycarbonyl (Boc)-protected APMA as the comonomer. A key step in this synthesis was the grafting of acetylene groups to the CNC surface via a reaction with NaOH plus propargyl bromide in aqueous dimethyl sulfoxide. The copolymer was attached to the CNCs using copper-catalyzed azide-alkyne cycloaddition (CuAAC) "click" chemistry. By determining the mean number of amino groups per copolymer and amino group content of the CNC sample, we were able to infer that there were on average ca. 300 polymer molecules per CNC. Preliminary evaluation in a human ovarian cancer cell line (HEYA8) and a human breast cancer cell line (MDA-MB-436) demonstrated that these CNCs are nontoxic. We also assessed the cellular uptake of these CNC NPs in the same two cell lines using flow cytometry and distinguished between NPs being internalized by the cell or surface-bound using a trypan blue quenching experiment. These results provide support for applications of polymer-coated CNCs in medicine and are encouraging for further studies in vitro and in vivo to evaluate their potential as drug-delivery vehicles.
具有长胶体纳米颗粒（NPs）的显著潜力在癌症治疗的药物传递和成像应用，但进展取决于开发更深入的了解其物理化学性质如何影响它们与细胞和肿瘤的相互作用。纤维素纳米晶体（CNC）是生物相容性的，棒状胶体，广泛的表面功能化，使它们作为模块化药物载体很有趣。在本报告中，我们描述了含有低聚乙二醇甲基丙烯酸酯（OEGMA；≈500 Da）和少量氨丙基甲基丙烯酰胺（APMA）的统计共聚物接枝到 CNC 的过程。在这里，共聚物设计为作为“隐形”的冠来最小化蛋白质吸附，而氨基提供了用于附着诊断或治疗部分的功能。带有末端叠氮基团的冠聚合物是通过原子转移自由基聚合使用 Boc 保护的 APMA 作为共聚单体合成的。该合成的一个关键步骤是通过在水溶液中的 NaOH 与丙炔溴反应将乙炔基团接枝到 CNC 表面。通过铜催化的叠氮-炔环加成（CuAAC）“点击”化学将共聚物连接到 CNC 上。通过确定每个共聚物的平均氨基数和 CNC 样品的氨基含量，我们能够推断出 CNC 上平均有约 300 个聚合物分子。在人卵巢癌细胞系（HEYA8）和人乳腺癌细胞系（MDA-MB-436）中的初步评估表明，这些 CNC 是无毒的。我们还使用流式细胞术评估了这些 CNC NPs 在相同两种细胞系中的细胞摄取，并使用台盼蓝猝灭实验区分 NPs 是被细胞内化还是表面结合。这些结果为聚合物涂覆的 CNC 在医学中的应用提供了支持，并鼓励进一步进行体外和体内研究，以评估它们作为药物传递载体的潜力。
