Dendritic polymer prodrug-based unimolecular micelles for pH-responsive co-delivery of doxorubicin and camptothecin with synergistic controlled drug release effect

Combination chemotherapy has been recognized as a more powerful strategy for tumor treatment rather than the single chemotherapy. However, the interactive mechanism of the two hydrophobic chemotherapeutic drugs has not been explored by now. Aiming for a better synergistic effect, such interactive mechanism was investigated in the present work, by designing CPT@DOX-DPUTEA-PEG nanomedicine with encapsulated camptothecin (CPT) and conjugated doxorubicin (DOX). The synergistic controlled drug release effect was found for the two drugs loaded on the different sites of the dendritic polyurethane core. Synergism was achieved on the HepG2 cells with a combination index (CI) of 0.58 in the in vitro cellular experiments. The results demonstrated the promising application of the unimolecular micelles-based nanomedicine with independently loading of two hydrophobic chemotherapeutic drugs.

Research Status of Dendrimer Micelles in Tumor Therapy for Drug Delivery

Dendrimers are a family of polymers with highly branched structure, well-defined composition, and extensive functional groups, which have attracted great attention in biomedical applications. Micelles formed by dendrimers are ideal nanocarriers for delivering anticancer agents due to the explicit study of their characteristics of particle size, charge, and biological properties such as toxicity, blood circulation time, biodistribution, and cellular internalization. Here, the classification, preparation, and structure of dendrimer micelles are reviewed, and the specific functional groups modified on the surface of dendrimers for tumor active targeting, stimuli-responsive drug release, reduced toxicity, and prolonged blood circulation time are discussed. In addition, their applications are summarized as various platforms for biomedical applications related to cancer therapy including drug delivery, gene transfection, nano-contrast for imaging, and combined therapy. Other applications such as tissue engineering and biosensor are also involved. Finally, the possible challenges and perspectives of dendrimer micelles for their further applications are discussed.

Phosphorylcholine zwitterionic shell-detachable mixed micelles for enhanced cancerous cellular uptakes and increased DOX release

To further enhance the cancerous cellular uptakes and increase the drug release of the drug loaded micelles, herein, we fabricated a series of mixed micelles with different mass ratios using two amphiphilic copolymers P(DMAEMA-co-MaPCL) and PCL-SS-PMPC. The mixed micelles showed a prolonged circulation time due to the zwitterionic shells in a physiological environment (pH 7.4). In addition, because of the protonation of tertiary amine groups in PDMAEMA and the breakage of the disulfide bond in PMPC-SS-PCL in a tumor microenvironment, the mixed micelles aggregated, which led to enhanced cancerous cellular penetration and increased DOX release. Moreover, cytotoxicity assay showed that the mixed micelles had good biocompatibility to L929, HeLa and MCF-7 cells, even at a concentration of up to 1 mg mL^-1. Furthermore, enhanced antitumour activity and cellular uptake of HeLa and MCF-7 cells were detected after loading with DOX, which was determined by confocal laser scanning microscopy (CLSM) and flow cytometry (FC), especially for the DOX@MIX 3 micelles (20% mass ratio of the P(DMAEMA-co-MaPCL)). Therefore, the mixed strategy provides a simple and efficient ways to promote anticancer drug delivery.

PEGylated dendritic polyurethane as unimolecular micelles for tumor chemotherapy: Effect of molecular architecture

Unimolecular micelles have attracted intense interests as drug carriers for tumor chemotherapy owing to their superior stability in comparison with the self-assembled supramolecular ones. Among them, the dendritic polymers with the polar frameworks could favour the loading of chemotherapeutic drugs rather than the hyperbranched polymers via radical polymerization, by enhancing the interaction with drugs. While the tedious synthesis procedure for dendritic polymers could be simplified with the construction principle on urethane chemistry. Here, the PEGylated dendritic polyurethanes, Ph-DPU_Gly-PEG and Ph-DPU_TEA-PEG, were designed with glycerol or triethanolamine as monomer, respectively. The effect of the molecular architecture of the Ph-DPU-PEGs unimolecular micelles on the controlled drug releasing performance was compared. It was found that the Ph-DPU_TEA-PEG with tertiary amine as branching points could efficiently endow the pH-triggered drug release, due to its protonation.

Facile Synthesis of a Redox-Responsive Hyperbranched Polymer Prodrug as a Unimolecular Micelle for the Tumor-Selective Drug Delivery

Demicellization of the self-assembled multimolecular micelles upon dilution restricts their application as drug delivery systems (DDSs) for tumor treatment. Here, a redox-responsive hyperbranched polymer prodrug (HBPP) was designed with a high drug content of 62.0% as a unimolecular micelle for the tumor-selective drug delivery, via the facile self-condensing vinyl polymerization (SCVP) of redox-responsive doxorubicin-based prodrug monomer MA-SS-DOX and poly(ethylene glycol) methacrylate (PEGMA) with p-chloromethylstyrene (CMS) as an inimer. The unimolecular micelle could be easily obtained with a hydrodynamic diameter of 122 nm, showing excellent GSH-triggered drug release performance with a cumulative release of 60.9% within 85 h but a low premature drug leakage of 3.2%. The unimolecular micelle exhibited selective tumor growth inhibition on HepG2 cells but no obvious cytotoxicity on L02 cells.

Facile synthesis of PEGylated dendritic polyurethane as unimolecular micelles for ultrasound-triggered localized drug delivery

PEGylated dendritic polyurethane was designed via a facile one-pot method as unimolecular micelles for ultrasound-triggered localized drug delivery.

H2O2-Responsive amphiphilic polymer with aggregation-induced emission (AIE) for DOX delivery and tumor therapy

Stimuli-responsive drug delivery systems (DDSs) based on amphiphilic polymers have attracted much attention. In this study, we reported an innovative H₂O₂-responsive amphiphilic polymer (TBP), bearing a H₂O₂-sensitive phenylboronic ester, AIE fluorophore tetraphenylethene (TPE) hydrophobic, and polyethylene glycol hydrophilic (PEG) moieties. TBP could self-assemble into micelles with an encapsulation efficiency as high as 74.9% for doxorubicin (DOX) in aqueous solution. In the presence of H₂O₂, TBP micelles was decomposed by oxidation, hydrolysis and rearrangement, leading to almost 80% DOX release from TBP@DOX micelles. TBP and the corresponding degradation products were biocompatible, while TBP@DOX micelles only displayed obvious toxicity toward cancer cells. Drug delivery process was clearly monitored by confocal laser scanning microscopic (CLSM) and flow cytometry (FCM) analysis. Moreover, in vivo anticancer study showed that TBP@DOX micelles were accumulated in tumor region of nude mice and effectively inhibited tumor growth. The results suggested that the reported H₂O₂-responsive amphiphilic polymer displayed great potential in drug delivery and tumor therapy.

Supramolecular dendrimer-containing layer-by-layer nanoassemblies for bioapplications: current status and future prospects

This review provides a comprehensive and critical overview of the supramolecular dendrimer-containing multifunctional layer-by-layer nanoassemblies driven by a multitude of intermolecular interactions for biological and biomedical applications.

Photocontrolled bromine–iodine transformation reversible-deactivation radical polymerization: facile synthesis of star copolymers and unimolecular micelles

A facile strategy of synthesizing star copolymers was successfully established via photocontrolled BIT-RDRP. The obtained copolymers have well-defined four-arm amphiphilic block architecture and can form stable unimolecular micelles in water.

Synthesis, Colloidal Characterization and Targetability of Phenylboronic Acid Functionalized α-Tocopheryl Polyethylene Glycol Succinate in Cancer Cells

This study reports targetable micelles developed after covalent functionalization of α-tocopheryl polyethylene glycol succinate (TPGS) with amino phenylboronic acid (APBA). Nuclear magnetic resonance (NMR) and infrared (IR) spectroscopic results showed successful attachment of APBA to the hydrophilic segment of TPGS. Dynamic light scattering and small-angle neutron scattering studies revealed that the conjugate self-assembled in water to produce spherical core-shell micelles (14–20 nm) which remained stable against temperature (ca. 25–45 °C) and pH changes. The micelles could solubilize a high payload of paclitaxel (PLX) without exhibiting changes in the average size. However, at the saturation solubility, drug molecules migrated from the core to the shell region and engaged with APBA groups via π–π stacking interaction. Confocal microscopy and cell sorting analyses verified the effective translocation ability of TPGS-APBA micelles in sialic acid (SA) expressing MDA-MB-453 cells. At equivalent PLX dose, TPGS-APBA micelles showed about a twofold improvement in apoptotic death among the cells exposed for 2 h. Our findings indicate that the attachment of APBA can be a potential strategy for improving the intra-cellular localization of carriers among cancer cells expressing SA residues.