The macroscopic molecular self-assembly of an amphiphilic hyperbranched copolymer in acetone generated multiwalled tubes millimeters in diameter and centimeters in length. The thickness of the tube walls approaches 400 nanometers, and the walls have an inhomogeneous lamella structure that alternates between ordered hydrophilic domains and amorphous, partly irregular hydrophilic domains.
This feature article describes the supramolecular self-assembly of hyperbranched polymers (HBPs), including the progress, unique characteristics and future perspectives. HBPs are irregular in molecular structure compared with that of linear block copolymers and dendrimers. However, similar to these well-defined polymer tectons, HBPs have displayed great potential to be excellent precursors in solution self-assembly, interfacial self-assembly and hybrid self-assembly. Many impressive supramolecular aggregates and hybrids at all scales and dimensions, such as macroscopic tubes, micro- or nano-vesicles, fibers, spherical micelles and honeycomb films, have been generated. In addition, HBPs also demonstrate unique characteristics or advantages in supramolecular self-assembly behaviours, including controllable morphologies and structures, special properties, characteristic self-assembly mechanism and facile functionalization process. Although still being at the early stage, self-assembly of HBPs has provided a new avenue for the development of supramolecular chemistry.
Cancer cells in hypoxic tumors are remarkably resistant to photodynamic therapy. Here, we hypothesize that an oxygen and Pt(II) self-generating multifunctional nanocomposite could reverse the hypoxia-triggered PDT resistance. The nanocomposite contains Pt(IV) and chlorin e6, in which upconversion nanoparticles are loaded to convert 980 nm near-infrared light into 365 nm and 660 nm emissions. Upon accumulation at the tumor site, a 980 nm laser is used to trigger the nanocomposite to generate O2 for consumption in the PDT process and to produce cytotoxic reactive oxygen species. The composite also releases active Pt(II) for synergistic photo-chemo therapy to enhance antitumor efficiency. The oxygen and Pt(II) self-generating prodrug is shown to have high potential to inhibit tumors out of the range of UV light, to overcome the hypoxia-triggered PDT resistance and significantly improve anticancer efficacy by the synergistic PDT-chemotherapy.
16 September 2004 in Angewandte Chemie International Edition