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Oxidation and Acid Milieu-Disintegratable Nanovectors with Rapid Cell-Penetrating Helical Polymer Chains for Programmed Drug Release and Synergistic Chemo-Photothermal Therapy

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journal contribution
posted on 05.10.2016, 17:03 by Yu Chen, Zhi-Huang Zhang, Xin Han, Jun Yin, Zong-Quan Wu
Polymeric assemblies are distinguished by ease of preparation, high drug-loading content, and long circulation time compared to small molecular, making them quite promising for cancerous diagnosis and therapy. However, the therapeutic efficacy of traditional nanocarriers with random coil surface is always proved to be less effective because of the existence of several systemic and cellular barriers or the low tissue penetration from nanocarrier itself. To fill this gap, we report a new class of oxidation and pH dual-responsive amphiphilic triblock copolymer: poly­(l-lactic acid)­(-IR780)-b-hydrophobic poly­(phenyl isocyanide)-b-hydrophilic poly­(phenyl isocyanide) (PLLA­(-IR780)-HBPPI-HPPPI). In neutral aqueous solution, the copolymers could form onion-like spherical micelles with diameter of ∼84 nm and consisting of PEGylated single left-handed helical PPI corona, endowing them rapid cell membrane permeability and internalization (10–20 min) that had an analogous effect of cell penetrating peptides (CPPs). Moreover, the phenylboronic pinacol ester contained in the hydrophobic interlayer was stable under neutral and weak acid milieu and thus could minimize the premature drug leakage and systemic cytotoxicity. Upon exposure to H2O2, the interlayer was oxidized rapidly and accompanied by a hydrophobic–hydrophilic transition, which resulted in the releasing of encapsulated drugs and creating interconnected hydrophilic channels to the inner PLLA core at the same time. An enhanced drug release from PLLA core was then achieved by the acid-triggered micelle degradation. The degradation rates of micelles and release rates of drugs could be easily tuned by changing the concentration of H2O2 and the acidity. The hyperthermia induced by the micelles could increase to as high as ∼48 °C upon near-infrared (NIR) light irradiation (808 nm, 1 W cm–2) due to the introduction of NIR absorptive IR780 dyes. Combined with the effect of chemotherapeutics, fatal and irreversible damage to cancer cells was observed. The primary objective of this research was to address the growing need for an effective/rapid drug delivery system and programmed/sustained on-demand drug release. We speculate that the newly developed multifunctional integrated micelles with combined advantages can potentially be utilized as a promising approach to disease diagnosis and therapy.