Facile Synthesis of Reductively Degradable Biopolymers Using Cystamine Diisocyanate as a Coupling Agent

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• 作者：Xiuxiu Wang ; Jian Zhang ; Ru Cheng ; Fenghua Meng ; Chao Deng ; Zhiyuan Zhong
• 刊名：Biomacromolecules
• 出版年：2016
• 出版时间：March 14, 2016
• 年：2016
• 卷：17
• 期：3
• 页码：882-890
• 全文大小：559K
• ISSN：1526-4602

文摘

Reductively degradable biopolymers have emerged as a unique class of smart biomedical materials. Here, a functional coupling agent, cystamine diisocyanate (CDI), was designed to offer a facile access to reductively degradable biopolymers via polycondensation with various diols. CDI was readily obtained with a decent yield of 46% by reacting cystamine dihydrochloride with triphosgene. The polycondensation of oligo(ethylene glycol) diol (M_n = 0.4 or 1.5 kg/mol) or oligo(ε-caprolactone) diol (M_n = 0.53 kg/mol) with CDI in N,N-dimethylformamide at 60 °C using dibutyltin dilaurate as a catalyst afforded reductively degradable poly(ethylene glycol) (SSPEG, M_n = 6.2–76.8 kg/mol) or poly(ε-caprolactone) (SSPCL, M_n = 6.8–16.3 kg/mol), in which molecular weights were well controlled by diol/CDI molar ratios. Moreover, PEG-SSPCL-PEG triblock copolymers could be readily prepared by reacting dihydroxyl-terminated SSPCL with PEG-isocyanate derivative. PEG-SSPCL-PEG with an M_n of 5.0–16.3–5.0 kg/mol formed small-sized micelles with an average diameter of about 85 nm in PB buffer. The in vitro release studies using doxorubicin (DOX) as a model drug showed that, in sharp contrast to reduction-insensitive PEG-PCL(HDI)-PEG controls, drug release from PEG-SSPCL-PEG micelles was fast and nearly complete in 24 h under a reductive condition containing 10 mM glutathione. The confocal microscopy experiments in drug-resistant MCF-7 cells (MCF-7/ADR) displayed efficient cytoplasmic DOX release from PEG-SSPCL-PEG micelles. MTT assays revealed that DOX-loaded PEG-SSPCL-PEG micelles were much more potent against MCF-7/ADR cells than reduction-insensitive PEG-PCL(HDI)-PEG controls (IC₅₀: 6.3 vs 55.4 μg/mL). It should further be noted that blank PEG-SSPCL-PEG micelles were noncytotoxic up to a tested concentration of 1 mg/mL. Hence, cystamine diisocyanate appears to be an innovative coupling agent that facilitates versatile synthesis of biocompatible and reductively degradable biopolymers.