A low-temperature synthesis method for preparing nanosized TiO2 crystallites has been developed based on a Pluronic F127 microemulsion system. Both anatase and rutile polymorphs can be prepared, and there exists a temperature window between 40 and 50 °C where the formation of rutile is favored over anatase. At 60 °C and above, anatase is kinetically favored and only very slowly transforms to rutile at 60 °C. The results differ from previous observations regarding formation kinetics and temperature range for rutile formation as well as in the microscopic aggregation of the formed nanoparticles. This development of a low-temperature synthesis of crystalline titania nanoparticles within the Pluronic block copolymer system is an important and enabling step toward devising a direct synthesis route for the formation of ordered mesoporous and crystalline titania.

Thin-film aggregation characteristics of a series of oligothiophenes with a central thieno[3,4-b]thiophene ester unit and 4 (M5), 8 (M9), and 16 (M17) regioregular hexylthiophene units were investigated. These oligomers exhibited length-dependent self-assembly characteristics upon spin coating. M9 formed long fibers, while M5 and M17 formed random domains. Grazing incidence x-ray diffraction was performed to understand the reason for this length dependence. The M5 had a dominant ester–ester interaction that disrupted long-range order. The M9 morphology was due to a balance of orthogonal backbone and ester effects, which imposed long-range order on the M9 aggregates. Meanwhile, the M17 ester chain had a smaller relative contribution to packing and functioned as a molecular defect, disrupting long-range order. As a result, though the local self-assembly between monomers was very similar for the molecules, backbone length dependent changes in intermolecular forces dominated long-range structure. The analysis of self-assembly characteristics in these materials provides guidance in the design of organic conjugated materials for use in semiconductor devices.

We have developed novel photovoltaic systems composed of the fullerene derivative (6,6)-phenyl C61 butyric acid methyl ester as electron acceptor with a second functional organic molecule, in this case bacteriochlorophyll c, as the light-harvesting and photosensitizing part. It was found that heat treatment of a thin film of bacteriochlorophyll c altered the morphological states of the aggregates and conductivity of the thin film could be regulated through the annealing process. Blended fullerene derivative and bacteriochlorophyll c thin films were fabricated on the surface of an indium-tin oxide/poly(ethylene dioxythiophene) doped with polystyrene sulfonic acid substrate layer and their photovoltaic properties were characterized and evaluated. Formation of fullerene-coordinated bacteriochlorophyll c complex was confirmed by changes in the visible absorption spectra and by FTIR. Such complexation promoted generation of photocurrent in the region of the Qyband and the current density of the thin film increased. A maximum incident photon-to-current conversion efficiency of 5.1% was attained at 745 nm.

The self-assembling properties of two rationally designed discotic π-conjugated hexaazatrinaphthylene (HATNA) molecules have been studied. In appropriate solvent systems, both ester-dodecyl-substituted and amide-dodecyl-substituted HATNAs self-assembled into nanowires and formed organogels. These nanowires could be easily transferred onto solid supports through spin casting for morphological study. In addition to the solution-based self-assembly method, solvent-vapor annealing (SVA) was explored as an alternative way to control the organization of supramolecular nanowires on surfaces. It was found that amorphous thin film of HATNA molecules transformed gradually into nanowire structures through a nucleation and growth mechanism during the SVA process. Several parameters including the preordering of molecules in the original thin film, choice of solvent vapors, annealing times, and surface properties were tuned to create different supramolecular organizations. Under particular conditions, aligned nanowires with preferential direction can be achieved.

Five lipids were self-assembled in aqueous dispersions into high axial ratio nanostructures. Thermal analysis was conducted on a glycolipid self-assembled into nanotubes, previously developed by Kamiya et al. [S. Kamiya, H. Minamikawa, J-H. Jung, B. Yang, M. Masuda, and T. Shimizu, Langmuir21, 743 (2005)], showing a dry melting onset of 148.2 °C and evidence of a highly ordered supramolecular structure. A novel hybrid structure of the glycolipid nanotubes decorated with silver nanoparticles was created. The self-assembly of four new amphiphiles, with serine and glutamic acid head groups attached to vaccenic acid and diacetylenic hydrophobic tails, was also investigated. The morphologies of these aggregates included high axial ratio nanostructures, such as nanotubes; and flat, twisted, and helical ribbons. The supramolecular aggregates of the five lipids reflect aspects of the molecular structure, such as chirality, providing evidence that such organized aggregates can be created by a rational approach to molecular design.

One of the challenges in the development of molecular scale devices is the integration of nano-objects or molecules onto desired locations on a surface. This integration comprises their accurate positioning, their alignment, and the preservation of their functionality. Here, we proved how capillary assembly in combination with soft lithography can be used to perform DNA molecular combing to generate chips of isolated DNA strands for genetic analysis and diagnosis. The assembly of DNA molecules is achieved on a topologically micropatterned polydimethylsiloxane stamp inducing almost simultaneously the trapping and stretching of single molecules. The DNA molecules are then transferred onto aminopropyltriethoxysilane-coated surfaces. In fact, this technique offers the possibility to tightly control the experimental parameters to direct the assembly process. This technique does not induce a selection in size of the objects, therefore it can handle complex solutions of long (tens of kbp) but also shorter (a few thousands of bp) molecules directly in solution to allow the construction of future one-dimensional nanoscale building templates.

In the literature, a few biological cells have been used as templates to form microcapsules of a variety of shapes and sizes. In this study, we proved the concept that living cells like platelets can be encapsulated with polyelectrolytes using electrostatic layer-by-layer self-assembly (LBL), and, most importantly, the encapsulation process did not induce activation of the platelets. Glycol-chitosan and poly-L-glutamic acid were electrostatically deposited onto platelets, and the encapsulation was confirmed using confocal laser scanning microscopy and scanning electron microscopy. Transmission electron microscopy observation further confirmed that the encapsulation process was mild and the activation of platelets was negligible. The encapsulation of living biological cells like platelets can serve as a model system in a wide range of biomedical applications including local and sustained drug delivery, immune protection of artificial tissues, and versatile artificial blood.