Fabrication of Robust Protein Films Using Nanoimprint Lithography.

A nanoimprint-lithography-based fabrication method to generate stable protein films is described. The process is environmentally friendly and generalizable with respect to the protein building blocks. These non-fouling surfaces are readily patternable, incorporate intrinsic protein charge into the film, and able to control cellular adhesion.

Effect of nano-scale curvature on the intrinsic blood coagulation system.

The intrinsic coagulation activity of silica nanoparticles strongly depends on their surface curvature. Nanoparticles with higher surface curvature do not denature blood coagulation factor XII on its surface, providing a coagulation 'silent' surface, while nanoparticles with lower surface curvature show denaturation and concomitant coagulation.

Rapid coating of surfaces with functionalized nanoparticles for regulation of cell behavior.

A robust monolayer of nanoparticles is formed via dip-coating of cell culture plates. These surfaces provide cell type-specific modulation of growth behavior without the uptake of nanoparticles.

Direct patterning of engineered ionic gold nanoparticles via nanoimprint lithography.

Gold nanoparticles are engineered for direct imprinting of stable structures. This imprinting strategy provides access to new device architectures, as demonstrated through the fabrication of a prototype photoswitchable device.

Chemoselective nanoporous membranes via chemically directed assembly of nanoparticles and dendrimers.

Chemoselective nanoporous membranes: tunably porous membranes with embedded functionalities are generated using a template-free, chemically directed nanoparticle-dendrimer (NP-Den) network assembly. This approach provides a direction in the design of post-functionalizable nanoporous membranes for distinguishing both organic molecules and proteins with excellent chemo- and bioselectivity.

Flavin as a photo-active acceptor for efficient energy and charge transfer in a model donor-acceptor system.

A donor-acceptor dyad model system using a flavin moiety as a photo-active acceptor has been synthesized for an energy and photo-induced electron transfer study. The photophysical investigations of the dyad revealed a multi-path energy and electron transfer process with a very high transfer efficiency. The photo-activity of flavin was believed to play an important role in the process, implying the potential application of flavin as a novel acceptor molecule for photovoltaics.

Cell alignment using patterned biocompatible gold nanoparticle templates.

Biocompatible structures are produced for cellular patterning. The biocompatible surfaces are generated to provide protein nonfouling patterns, offering direct communication to the cells for controlling cell adhesion and proliferation. These biofunctional surfaces provide a platform for aligning the cells in the direction of patterns, indicating potential application in the field of tissue engineering.

Recognition-mediated assembly of quantum dot polymer conjugates with controlled morphology.

We have demonstrated a polymer mediated "bricks and mortar" method for the self-assembly of quantum dots (QDs). This strategy allows QDs to self-assemble into structured aggregates using complementary three-point hydrogen bonding. The resulting nanocomposites have distinct morphologies and inter-particle distances based on the ratio between QDs and polymer. Time resolved photoluminescence measurements showed that the optical properties of the QDs were retained after self-assembly.

Supramolecular functionalization of electron-beam generated nanostructures.

Electron-beam lithography was used to pattern poly(styrene-co-(methyldiaminotriazine) styrene) (PS-Triaz). These polymer nanopatterns were utilized as molecular scaffolds for assembling complementary thymine-functionalized CdSe-ZnS quantum dots (Thy-QDs) via three-point hydrogen-bonding molecular recognition. This interaction was very specific, with N-methyl thymine-functionalized QDs (MeThy-QDs) not depositing on the surfaces. The "lock and key" specificity of the assembly is mirrored in the disassembly process, where complete removal of the QD was observed using a competing thymine guest.

Drug encapsulation within self-assembled microglobules formed by thermoresponsive supramolecules.

An 8-(phenyl)-2'-deoxyguanosine derivative self-assembles in aqueous media into discrete hexadecamers that further self-assemble above 32 °C into microglobules that encapsulate the drug doxorubicin.

Nanoimprint lithography for functional three-dimensional patterns.

Nanoimprint lithography (NIL) is viewed as an alternative nanopatterning technique to traditional photolithography, allowing micrometer-scale and sub-hundred-nanometer resolution as well as three-dimensional structure fabrication. In this Research News article we highlight current activities towards the use of NIL in patterning active or functional materials, and the application of NIL in patterning materials that present both chemistry and structure/topography in the patterned structures, which provide scaffolds for subsequent manipulation. We discuss and give examples of the various materials and chemistries that have been used to create functional patterns and their implication in various fields as electronic and magnetic devices, optically relevant structures, biologically important surfaces, and 3D particles.

Synthesis and use of self-assembled rhamnolipid microtubules as templates for gold nanoparticles assembly to form gold microstructures.

Natural unmodified rhamnolipids are thermally self-assembled into soft microtubules, which can produce gold nanoparticles onto themselves due to the presence of rhamnose sugar moieties at their surface. The loading of gold nanoparticles on composite microtubules can be controlled by varying the concentration of gold salt to rhamnolipid and the reaction temperature. The composite rhamnolipid-gold nanoparticle microtubules are then heat treated to produce porous gold microwire-like structures with fairly controlled nanostructured features, which may have interesting applications in catalysis, biosensing and electronics.

Recognition mediated encapsulation and isolation of flavin-polymer conjugates using dendritic guest moieties.

Diaminopyridine dendritic scaffolds encapsulate polymeric flavin via non-covalent interactions and demonstrate isolation of the redox moiety.

Photooxidation of Nanopatterned Poly(chloromethylstyrene): Direct Formation of Crosslinked Aldehyde-Functionalized Films for Chemical Functionalization and Bioconjugation.

UV irradiation of chloromethyl styrene simultaneously crosslinks the polymer and generates aldehyde groups that can be employed for polymer surface functionalization through aldehyde-imine/hydrazone chemistry. Using this method, we successfully have functionalized nanoimprinted polymer patterns with dyes, nanoparticles, and enzymes. These surfaces were characterized by infrared (ATR-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), fluorescence microscopy, and enzymatic activity assays.

Molecular recognition at the liquid-liquid interface of colloidal microcapsules.

Dithiocarbamate chemistry is used as a crosslinking tool to fabricate FePt colloidal microcapsules which provide a versatile scaffold for "host-guest" recognition at the liquid-liquid interface.

Model systems for flavoenzyme activity: intramolecular self-assembly of a flavin derivative via hydrogen bonding and aromatic interactions.

We have synthesised a flavin derivative incorporating functionalities that promote intramolecular self-assembly via hydrogen bonding and aromatic interactions.

Self-assembly and cross-linking of FePt nanoparticles at planar and colloidal liquid-liquid interfaces.

Terpyridine thiol functionalized FePt and Au NPs were self-assembled and cross-linked at the liquid-liquid interfaces using Fe(II) metal ion. Complexation of terpyridine with Fe(II) metal ion leads to NP network and affords stable membranes and colloidal shells at the liquid-liquid interfaces.