Orthogonal patterning of multiple biomolecules using an organic fluorinated resist and imprint lithography.

The ability to spatially deposit multiple biomolecules onto a single surface with high-resolution while retaining biomolecule stability and integrity is critical to the development of micro- and nanoscale biodevices. While conventional lithographic patterning methods are attractive for this application, they typically require the use of UV exposure and/or harsh solvents and imaging materials, which may be damaging to fragile biomolecules. Here, we report the development of a new patterning process based on a fluorinated patterning material that is soluble in hydrofluoroether solvents, which we show to be benign to biomolecules, including proteins and DNA. We demonstrate the implementation of these materials into an orthogonal processing system for patterning multibiomolecule arrays by imprint lithography at room temperature. We further showcase this method's capacity for fabricating patterns of receptor-specific ligands for fundamental cell studies.

Fullerene/thiol-terminated molecules.

A series of fullerene-terminated oligo(phenylene ethynylene) (OPEs) have been synthesized for potential use in electronic or optoelectronic device monolayers. Electronic properties such as the energy levels and the distribution of HOMOs and LUMOs of fullerene-terminated OPEs have been calculated using the ab initio method at the B3LYP/6-31G(d) level. The calculations have revealed the concentration of frontier orbitals on the fullerene cage and a narrow distribution of HOMO-LUMO energy gaps. Ultraviolet photoelectron spectroscopy and inverse photoemission spectroscopy studies have been performed to further examine the electronic properties of the fullerene-terminated OPEs on gold surfaces. The obtained broad photoelectron spectra suggest that there are strong intermolecular interactions in the fullerene self-assembled monolayers, and the small bandgap (approximately 1.5 eV), determined by the photoelectron spectroscopy, indicates the unique nature of the fullerene-terminated OPEs in which the C(60) moiety can be connected to the Au surface through the conjugated OPE backbone.

Cross-linkable molecular glasses: low dielectric constant materials patternable in hydrofluoroethers.

We report a new approach to solution-processable low-dielectric-constant (low-k) materials including photolithographic patterning of these materials in chemically benign and environmentally friendly solvents. A series of semiperfluorinated molecular glasses with styrenic substituents were successfully synthesized. These small molecular materials were thermally stable up to 400 degrees C and also exhibited an amorphous nature, which is essential to forming uniform films. Differential scanning calorimetry studies revealed that a cross-linking reaction occurred in the presence of acid, resulting in the formation of robust polymeric films. Atomic force microscopy images of the cross-linked films showed uniform and pinhole-free surface properties. Dielectric constants determined by a capacitance measurement were 2.6-2.8 (100 kHz) at ambient conditions, which are comparable to other polymeric low-k materials. The incorporation of semiperfluorinated substituents was effective in decreasing the dielectric constant; in particular, the fluorinated alkyl ether structure proved best. In addition, the fluorinated substituents contributed to good solubility in hydrofluoroether (HFE) solvents, which enabled the successful photolithographic patterning of those materials in HFEs down to a submicrometer scale.

Acid-sensitive semiperfluoroalkyl resorcinarene: an imaging material for organic electronics.

An acid-sensitive semiperfluoroalkyl resorcinarene was synthesized, and its lithographic properties were evaluated. Its solubility in segregated hydrofluoroether solvents enables the patterning of delicate organic electronic materials.