Macromolecular self-assembly and nanotechnology in China

Polypeptide self-assemblies: nanostructures and bioapplications

Polypeptide copolymers can self-assemble into diverse aggregates. The morphology and structure of aggregates can be varied by changing molecular architectures, self-assembling conditions, and introducing secondary components such as polymers and nanoparticles. Polypeptide self-assemblies have gained significant attention because of their potential applications as delivery vehicles for therapeutic payloads and as additives in the biomimetic mineralization of inorganics. This review article provides an overview of recent advances in nanostructures and bioapplications related to polypeptide self-assemblies. We highlight recent contributions to developing strategies for the construction of polypeptide assemblies with increasing complexity and novel functionality that are suitable for bioapplications. The relationship between the structure and properties of the polypeptide aggregates is emphasized. Finally, we briefly outline our perspectives and discuss the challenges in the field.

Extraordinary boundary morphologies of large-scale ordered domains of spheres in thin films of a narrowly dispersed diblock copolymer via thermodynamic control

Long-range ordering of body centered cubic (BCC) spheres and various extraordinary morphologies at the boundaries of the adjacent orderly oriented domains are observed in thermally annealed thin films of a series of specific narrowly dispersed diblock copolymers, poly(dimethylsiloxane)-b-poly{2,5-bis[(4-butoxyphenyl)oxycarbonylstyrene} (PDMS-b-PBPCS, DB). The series of asymmetrical DB block copolymers (BCPs) with volume fractions of PDMS (f(PDMS)'s) from 10% to 23% self-assemble into thermodynamically stable body centered cubic (BCC) nanostructures in bulk at ambient temperature after thermal annealing. The thin films of these BCPs with a relatively large film thickness on a carbon-film coated substrate are annealed in a vacuum at 180 °C for 3 days and are characterized by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). For all thin films of these BCPs, micrometer-scale domains with a rectangular unit cell similar to the projection of the BCC lattice along the [110] direction to the substrate are observed. And the XPS results indicate that the surface layers of the thin films are composed of both PDMS and PBPCS blocks. For the thin films of the BCPs with f(PDMS) values of 10% and 13%, the neighboring [110]-oriented BCC domains match well with each other, and the boundaries are defect-free. For the thin film of the BCP with a f(PDMS) value of 23%, the PDMS spheres in the [110]-oriented BCC domains in the TEM micrograph are overlapped with each other, and interesting morphologies including defect-free interfaces, interfaces with line defects, and domains with defects and local ordering are observed at the boundaries of the neighboring [110]-oriented domains.

Concentration-dependent and light-responsive self-assembly of bolaamphiphiles bearing α-cyanostilbene based photochromophore

In this paper, a new bolaamphiphile bearing 1-cyano-1,2-bis(phenyl)ethene (CNBE) has been synthesized. The self-assembly of this molecule in aqueous solution is concentration-dependent. Two distinct morphologies, monomolecular layered lamellas and helical nanofibres have been obtained with the as-prepared molecular configuration. Note worthily, the helical nanofibres provide an experimental evidence for the pure twisted structure in the liquid crystals, which is theoretically proposed by De Gennes. Due to the photoisomerization of CNBE, the self-assembled nanostructures undergo morphological changes upon irradiation. Although various nanostructures were observed in the solution-state, only nanofibres were obtained after the solution was cast on a substrate, which was attributed to a strong dewetting effect. This work illustrates concentration-dependent and light-responsive self-assembly and provides a novel avenue for fabricating smart soft materials.

Self-assembly of supramolecularly engineered polymers and their biomedical applications

Self-assembly behavior of supramolecularly engineered polymers and their biomedical applications have been summarized.