Alferiev Ivan S, Fishbein Ilia, Levy Robert J, Chorny Michael
Division of Cardiology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104-4318, United States; The University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104-4318, United States.
ACS Appl Polym Mater. 2022 Feb 11;4(2):1196-1206. doi: 10.1021/acsapm.1c01601. Epub 2022 Jan 6.
Aliphatic polyesters are among materials most extensively used for producing biodegradable polymeric nanoparticles currently in development as delivery carriers and imaging agents for a range of biomedical applications. Their clinical translation requires robust particle labeling methodologies that allow reliably monitoring the fate of these formulations in complex biological environments. In the present study, a practical and versatile synthetic strategy providing conjugates of poly(D,L-lactide) representative of this class of polymers with BODIPY fluorophores varying in functional groups and excitation/emission maxima was investigated as a tool for making traceable nanoparticles. Polymer-probe conjugation was accomplished by carbodiimide-induced and 4-(dimethylamino)pyridinium 4-toluenesulfonate-catalyzed esterification of the polymer's terminal hydroxyl group, either directly with a carboxy-functionalized fluorophore or with amine-protected amino acids (Boc-glycine or Boc-6-aminohexanoic acid). In the latter case, the amino acid-derivatized polymeric precursors were reacted with amine-reactive BODIPY dyes after the removal of the protective group. Unlike nanoparticles encapsulating a strongly hydrophobic BODIPY (logP = 4.3), nanoparticles labeled covalently with its carboxy-functionalized analogue (BODIPY FL) demonstrated stable particle-tracer association under perfect sink conditions. Furthermore, in contrast to the encapsulated dye rapidly partitioning from particles onto cell membranes but not stably retained by cultured cells, the internalization of the covalently attached probe was an irreversible process requiring the presence of serum, consistent with active nanoparticle uptake by endocytosis. In conclusion, the conjugation of particle-forming polymers with BODIPY fluorophores offers an effective and accessible labeling strategy for making traceable polyester-based biodegradable nanoparticles and is expected to facilitate their development and optimization as therapeutic carriers and diagnostic agents.
脂肪族聚酯是目前正在开发的用于生产可生物降解聚合物纳米颗粒的材料之一，这些纳米颗粒可用作一系列生物医学应用的递送载体和成像剂。它们的临床转化需要强大的颗粒标记方法，以便在复杂的生物环境中可靠地监测这些制剂的命运。在本研究中，研究了一种实用且通用的合成策略，该策略提供了此类聚合物的代表聚（D，L-丙交酯）与官能团和激发/发射最大值不同的BODIPY荧光团的缀合物，作为制备可追踪纳米颗粒的工具。聚合物-探针缀合是通过碳二亚胺诱导和4-（二甲基氨基）吡啶四甲苯磺酸盐催化的聚合物末端羟基的酯化反应完成的，该反应可以直接与羧基官能化的荧光团或与胺保护的氨基酸（Boc-甘氨酸或Boc-6-氨基己酸）反应。在后一种情况下，氨基酸衍生的聚合物前体在去除保护基团后与胺反应性BODIPY染料反应。与包封强疏水性BODIPY（logP = 4.3）的纳米颗粒不同，用其羧基官能化类似物（BODIPY FL）共价标记的纳米颗粒在理想的下沉条件下表现出稳定的颗粒-示踪剂结合。此外，与包封的染料迅速从颗粒分配到细胞膜上但未被培养细胞稳定保留相反，共价连接的探针的内化是一个不可逆的过程，需要血清的存在，这与通过内吞作用主动摄取纳米颗粒一致。总之，将成粒聚合物与BODIPY荧光团缀合为制备可追踪的基于聚酯的可生物降解纳米颗粒提供了一种有效且可行的标记策略，有望促进其作为治疗载体和诊断剂的开发和优化。
