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Adv Healthc Mater. 2014 Mar;3(3):441-8. doi: 10.1002/adhm.201300235. Epub 2013 Aug 30.

Poly(ethylene oxide)-block-polyphosphoester-graft-paclitaxel conjugates with acid-labile linkages as a pH-sensitive and functional nanoscopic platform for paclitaxel delivery.

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Departments of Chemistry and Chemical Engineering, Laboratory for Synthetic-Biologic Interactions, Texas A&M University, P.O. Box 30012, 3255 TAMU, College Station, TX, 77842, USA.


There has been an increasing interest to develop new types of stimuli-responsive drug delivery vehicles with high drug loading and controlled release properties for chemotherapeutics. An acid-labile poly(ethylene oxide)-block-polyphosphoester-graft-PTX drug conjugate (PEO-b-PPE-g-PTX G2) degradable, polymeric paclitaxel (PTX) conjugate containing ultra-high levels of PTX loading is improved significantly, in this second-generation development, which involves connection of each PTX molecule to the polymer backbone via a pH-sensitive β-thiopropionate linkage. The PEO-b-PPE-g-PTX G2 forms well-defined nanoparticles in an aqueous solution, by direct dissolution into water, with a number-averaged hydrodynamic diameter of 114 ± 31 nm, and exhibits a PTX loading capacity as high as 53 wt%, with a maximum PTX concentration of 0.68 mg mL(-1) in water (vs 1.7 μg mL(-1) for free PTX). The PEO-b-PPE-g-PTX G2 shows accelerated drug release under acidic conditions (≈50 wt% PTX released in 8 d) compared with neutral conditions (≈20 wt% PTX released in 8 d). Compared to previously reported polyphosphoester-based PTX drug conjugates, PEO-b-PPE-g-PTX G1 without the β-thiopropionate linker, the PEO-b-PPE-g-PTX G2 shows pH-triggered drug release property and 5- to 8-fold enhanced in vitro cytotoxicity against two cancer cell lines.


pH-triggered release; paclitaxel; polymer-drug conjugates; polyphosphoester; thiol-ene

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