Macroporous honeycomb films of surfactant-encapsulated polyoxometalates at air/water interface and their electrochemical properties

Breath Figure Method for Construction of Honeycomb Films

Honeycomb films with various building units, showing potential applications in biological, medical, physicochemical, photoelectric, and many other areas, could be prepared by the breath figure method. The ordered hexagonal structures formed by the breath figure process are related to the building units, solvents, substrates, temperature, humidity, air flow, and other factors. Therefore, by adjusting these factors, the honeycomb structures could be tuned properly. In this review, we summarized the development of the breath figure method of fabricating honeycomb films and the factors of adjusting honeycomb structures. The organic-inorganic hybrid was taken as the example building unit to discuss the preparation, mechanism, properties, and applications of the honeycomb films.

Vortex-aligned fullerene nanowhiskers as a scaffold for orienting cell growth

A versatile method for the rapid fabrication of aligned fullerene C60 nanowhiskers (C60NWs) at the air-water interface is presented. This method is based on the vortex motion of a subphase (water), which directs floating C60NWs to align on the water surface according to the direction of rotational flow. Aligned C60NWs could be transferred onto many different flat substrates, and, in this case, aligned C60NWs on glass substrates were employed as a scaffold for cell culture. Bone forming human osteoblast MG63 cells adhered well to the C60NWs, and their growth was found to be oriented with the axis of the aligned C60NWs. Cells grown on aligned C60NWs were more highly oriented with the axis of alignment than when grown on randomly oriented nanowhiskers. A study of cell proliferation on the C60NWs revealed their low toxicity, indicating their potential for use in biomedical applications.

Hedgehog-shaped {Mo368} cluster: unique electronic/structural properties, surfactant encapsulation and related self-assembly into vesicles and films

The hedgehog-shaped {Mo368} cluster shows unique electronic (extremely high extinction coefficient) and structural features, especially regarding its size, the high number of delocalized electrons which allows to measure the surface enhanced Raman scattering (SERS) spectrum and the option for coordination chemistry inside the cavity. Its relative instability in aqueous solution can be overcome by embedment in a hydrophobic shell of dimethyldioctadecylammonium cations. The resulting hybrid self-assembles into spherical vesicles in acetone-water mixtures, according to a process directed by hydrophobic-hydrophilic interactions. It also forms rather stable Langmuir monolayers while a second layer evolves under higher surface pressure, in accordance with a rather low alkyl surface density.

Multiple interfaces in self-assembled breath figures

Progress in the breath figure method is reviewed by emphasizing the role of the multiple interfaces and the applications of honeycomb films in separation, biocatalysis, biosensing, templating, stimuli-responsive surfaces and adhesive surfaces.

Au NP honeycomb-patterned films with controllable pore size and their surface-enhanced Raman scattering

Honeycomb-patterned films (HPFs) of Au nanoparticles (Au NPs) with pore size controlled by varying the quantity of Au NPs or using modified agents of different mercaptans (C14H29SH, C16H33SH, and C18H37SH) were prepared. The strength of the HPFs containing Au NPs can be enhanced because of the addition of polymers including polystyrene, poly(l-lactic acid), and poly(methyl methacrylate-co-ethyl acrylate). With an increase in the amount of polymer and the number of Au NPs or the chain length of the modified agents, the pore size of HPFs decreases, indicating that the pore size can be well controlled by adjusting the above factors. Interestingly, HPFs with elliptical pores that were created by the direction of the air flow were observed. The pore diameter on the outer rim is smaller than that in the center, which should be because of the subordinate evaporation of the solvent in the center. Sponge structures were observed in the cross sections of the walls of HPFs, which should be produced by microphase separation. The HPFs consisting of Au NPs with controllable pore size exhibited stronger surface-enhanced Raman scattering. We believe that the HPFs composed of metal NPs such as Au, Ag, and Cu are exploited in multispectral scanners, nanophotons, and sensors.

Advances in Fabrication Materials of Honeycomb Structure Films by the Breath-Figure Method

Creatures in nature possess almost perfect structures and properties, and exhibit harmonization and unification between structure and function. Biomimetics, mimicking nature for engineering solutions, provides a model for the development of functional surfaces with special properties. Recently, honeycomb structure materials have attracted wide attention for both fundamental research and practical applications and have become an increasingly hot research topic. Though progress in the field of breath-figure formation has been reviewed, the advance in the fabrication materials of bio-inspired honeycomb structure films has not been discussed. Here we review the recent progress of honeycomb structure fabrication materials which were prepared by the breath-figure method. The application of breath figures for the generation of all kinds of honeycomb is discussed.