Stimuli-responsive drug delivery systems (DDSs) offering spatial-temporal and dosage controlled transport of drugs in vivo have attracted much attention for anticancer drug delivery. In the present work, a kind of phenylboronic ester-linked PEG-lipid conjugate was designed and synthesized for H2O2-responsive drug delivery. Firstly, a chain-end alkynyl functionalized methoxy poly(ethylene glycol) with a phenylboronic pinacol ester linker was synthesized via a classical Passerini reaction of carboxyl functionalized methoxy poly(ethylene glycol)2000 (mPEG2k-COOH), 4-formylphenylboronic pinacol ester and propargyl isocyanoacetamide. The obtained polymer was denoted as mPEG2k-PBPE-alkynyl. Then, the oxidation-responsive cleavage of the phenylboronic pinacol ester linker between the mPEG2k-COOH and alkynyl chain-end was verified by in situ1H NMR and mass spectra characterization. Furthermore, the amphiphilic PEG-lipid conjugate was synthesized by the Cu(I)-catalyzed click reaction of mPEG2k-PBPE-alkynyl and 3-azido-1,2-propanediol distearate (N3-DSA). The resultant mPEG2k-PBPE-DSA could self-assemble into stable micelles in aqueous media. Nile red was used as the model drug and was loaded into the micelles. The obtained drug loaded micelles exhibited a typical H2O2-responsive drug release behavior and could be effectively internalized by MCF-7 cells. In addition, the synthesized mPEG2k-PBPE-DSA was tested to be nontoxic towards RAW264.7 cells. Therefore, this biocompatible mPEG2k-PBPE-DSA conjugate would be promising for applications in ROS-responsive drug delivery.

Correction for ‘Biocompatible reduction-responsive polypeptide micelles as nanocarriers for enhanced chemotherapy efficacy in vitro’ by Jianxun Ding et al., J. Mater. Chem. B, 2013, 1, 69–81.

Correction for ‘Enhanced endocytosis of acid-sensitive doxorubicin derivatives with intelligent nanogel for improved security and efficacy’ by Jianxun Ding et al., Biomater. Sci., 2013, 1, 633–646.

The acid-sensitive PEGylated doxorubicin (DOX) with exact chemical structure was designed and prepared as a potential tumor intracellular microenvironment-responsive drug delivery system. First, the insensitive succinic anhydride-functionalized DOX (i.e., SAD) and acid-sensitive cis-aconitic anhydride-modified DOX (i.e., CAD) were synthesized through the ring-opening reaction. Subsequently, the insensitive and acid-sensitive PEGylated DOX (i.e., mPEG-SAD and mPEG-CAD) was prepared by the condensation reaction between the terminal hydroxyl group of mPEG and the carboxyl group in SAD and CAD, respectively. The obtained mPEG-SAD and mPEG-CAD could spontaneously self-assemble into micelles in phosphate-buffered saline at pH 7.4 with diameters of about 100 nm. The DOX release of mPEG-CAD micelle could be accelerated by the decrease of pH from 7.4, 6.8, to 5.5 in relation to that of mPEG-SAD micelle. On the other hand, the result of the cellular proliferation inhibition test indicated that mPEG-CAD micelle exhibited favorable antiproliferative activity in vitro. In addition, the selective intratumoral accumulation and antitumor efficacy of mPEG-CAD micelle were significantly better than those of free DOX and mPEG-SAD. More importantly, the prodrug micelles exhibited upregulated security in vivo as compared to free DOX. Overall, the mPEG-CAD micelle with enhanced antitumor efficacy and decreased side effects was a fascinating prospect for the clinical chemotherapy of malignancy.Keywords: acid-sensitive; controlled drug delivery; doxorubicin; malignancy therapy; poly(ethylene glycol)

Correction for ‘Enhanced endocytosis of acid-sensitive doxorubicin derivatives with intelligent nanogel for improved security and efficacy’ by Jianxun Ding et al., Biomater. Sci., 2013, 1, 633–646.

Correction for ‘Biocompatible reduction-responsive polypeptide micelles as nanocarriers for enhanced chemotherapy efficacy in vitro’ by Jianxun Ding et al., J. Mater. Chem. B, 2013, 1, 69–81.