Synthesis, Degradation, and Cytotoxicity of Multiblock Poly(ε-caprolactone urethane)s Containing Gemini Quaternary Ammonium Cationic Groups

Self-reinforced endocytoses of smart polypeptide nanogels for "on-demand" drug delivery

The pH and reduction dual-responsive polypeptide nanogels with self-reinforced endocytoses were prepared through ring-opening polymerization of l-glutamate N-carboxyanhydrides, deprotection of benzyl group and subsequent quaternization reaction between γ-2-chloroethyl-l-glutamate unit in polypeptide block and 2,2'-dithiobis(N,N-dimethylethylamine). The nanogels were revealed to exhibit smart pH and reduction dual-responsiveness, and excellent biocompatibilities, which expressed great potential as antitumor drug nanocarriers. Doxorubicin (DOX) as a model antitumor drug was loaded into nanogels through dispersion. DOX-loaded nanogels displayed a stable core-cross-linked structure under normal physiological condition (pH7.4), while rapidly releasing the payloads in the mimicking endosomal (pH5.3), tumor tissular (pH6.8) or intracellular reductive microenvironments (10.0mM glutathione). Confocal fluorescence microscopy demonstrated that DOX-loaded nanogels could deliver DOX into HepG2 cells (a human hepatoma cell line) more efficiently than the parent DOX-loaded micelle and free DOX. The enhanced cellular internalizations of DOX-loaded nanogels were more significant under tumor tissular acidic condition (pH6.8) ascribed to the quaternary ammonium groups in the cores. In addition, DOX-loaded nanogels exhibited improved in vitro and in vivo antitumor activities, and in vivo securities compared with DOX-loaded micelle and free DOX. These excellent features of the smart nanogels with quaternary ammonium groups were endowed with a bright prospect for intracellular targeting antitumor drug delivery.

Degradable polyurethane for marine anti-biofouling

Degradable polyurethane (PU) with copolyester oligomer consisting of ε-caprolactone (CL) and glycolide (GA) as the soft segments has been prepared by a combination of ring-opening polymerization and condensation reaction. Enzymatic and hydrolytic degradation experiments demonstrate that the PU can degrade in seawater. Such a polyurethane exhibit a more rapid degradation in comparison with that with poly(ε-caprolactone) (PCL) soft segments because the introduction of GA can reduce the crystallinity, as revealed by differential scanning calorimetry (DSC) and polarizing optical microscope (POM). Marine field tests show that the degradable polyurethane has good antifouling ability due to its self-renewal property. Besides, such polyurethane can serve as a carrier and controlled release system for an antifoulant, and the incorporation of an antifoulant in the polyurethane can significantly improve the antifouling ability and duration.

Characteristics of polyurethane-based sustained release membranes for drug delivery

This paper is focused on the preparation and physicochemical characterization of two poly(ester ether urethane)s with rifampicin in their matrix and different molar concentrations of urethane groups. The polyurethanes with rifampicin were processed as asymmetrical microporous membranes by a phase inversion method and characterized by attenuated total reflection — Fourier transform infrared (ATR-FTIR) spectroscopy and differential scanning calorimetry (DSC). The influence of the surface morphology in the release of drug compounds was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle, and water uptake. The release of rifampicin depends on the molar concentration of urethane groups and also on the surface morphology of the polyurethane membranes. The antibacterial activity was evaluated with S. Epidermidis RP 62 A and P. Aeruginosa ATCC 1544. Finally, the biocompatibility of the polyurethane membranes was studied with human dermal fibroblasts (HDF) to evaluate the potential biomedical applications.

Toward the next-generation nanomedicines: design of multifunctional multiblock polyurethanes for effective cancer treatment

Specific accumulation of therapeutics at tumor sites to improve in vivo biodistribution and therapeutic efficacy of anticancer drugs is a major challenge for cancer therapy. Herein, we demonstrate a new generation of intelligent nanosystem integrating multiple functionalities in a single carrier based on multifunctional multiblock polyurethane (MMPU). The smart nanocarriers equipped with stealth, active targeting, and internalizable properties can ferry paclitaxel selectively into tumor tissue, rapidly enter cancer cells, and controllably release their payload in response to an intracellular acidic environment, thus resulting in an improved biodistribution and excellent antitumor activity in vivo. Our work provides a facile and versatile approach for the design and fabrication of smart intracellular targeted nanovehicles for effective cancer treatment, and opens a new era in the development of biodegradable polyurethanes for next-generation nanodelivery systems.

An Approach for the Sphere-to-Rod Transition of Multiblock Copolymer Micelles

The shape of polymer micelles is important for pharmaceutical applications as drug delivery. In this article, an approach inducing sphere-to-rod transition of multiblock polyurethane micelles has been developed through introducing a second hydrophilic component phosphatidylcholine group into the polymer chains. Time-resolved dynamic light scattering (DLS), combined with transmission electron microscopy (TEM), was employed to investigate the kinetics of morphology transition. Moreover, a dissipative particle dynamics (DPD) simulation method was applied to study the mechanism of sphere-to-rod transition. These experimental and simulation studies revealed that the hydrophilic phosphatidylcholine groups can create defects on the surfaces of spherical polyurethane micelles, thus, making positive contribution to adhesive collisions and leading to the fusion of spherical micelles into rod-like micelles. This finding provides new insight into the origins of rod-like polymer micelles, which is valuable for the design and preparation of novel polymeric drug carriers with tailored properties.

Molecular engineered super-nanodevices: smart and safe delivery of potent drugs into tumors

A super-nanodevice engineered at molecular level integrates various desired properties in a smart and coordinated way, and can "switch on" or "turn off" certain functionalities as required. Importantly, it can break through complex physiological barriers, and then precisely ferry potent toxic triptolide into tumor cells in vivo, thus significantly maximizing the therapeutic efficacy and reducing the drug toxicity.