ABSTRACT
We present a discussion of the use of vertically-aligned carbon nanofibers (VACNFs) as nanoscale elements that directly interface to biological whole-cell systems. VACNFs are compatible with a large subset of microfabrication processes, thereby enabling their incorporation into mesoscale hybrid systems that provide addressability of the VACNFs as either bulk electrode material, or as individually addressed nanoelectrodes. These VACNF devices are compatible with cell cultures, and electrochemical addressability of nanofibers can be maintained for extended periods within cell cultures. We present results that demonstrate possible use of VACNF devices as electrical and genetic substrates for tissue scaffolding applications.
Subject(s)
Cell Culture Techniques/methods , Drug Carriers/chemistry , Electric Stimulation/methods , Electroporation/methods , Nanotubes, Carbon/chemistry , Nanotubes, Carbon/ultrastructure , Tissue Culture Techniques/methods , Transfection/methods , Materials Testing , Particle SizeABSTRACT
We report an effective method for the production of ultrasharp vertically oriented silicon nanocones with tip radii as small as 5 nm. These silicon nanostructures were shaped by a high-temperature acetylene and ammonia dc plasma reactive ion etch (RIE) process. Thin-film copper deposited onto Si substrates forms a copper silicide (Cu3Si) during plasma processing, which subsequently acts as a seed material masking the single-crystal cones while the exposed silicon areas are reactive ion etched. In this process, the cone angle is sharpened continually as the structure becomes taller. Furthermore, by lithographically defining the seed material as well as employing an etch barrier material such as titanium, the cone location and substrate topography can be controlled effectively.
Subject(s)
Copper/chemistry , Nanostructures/chemistry , Silicon/chemistry , Acetylene/chemistry , Ammonia/chemistry , Electrochemistry/methods , Microscopy, Electron, Scanning , Nanostructures/ultrastructure , X-Ray DiffractionABSTRACT
Electroosmotic manipulation of fluids was demonstrated using thin metal electrodes integrated within microfluidic channels at the substrate and cover plate interface. Devices were fabricated by photolithographically patterning electrodes on glass cover plates that were then bonded to polymeric substrates into which the channels were cast. Polymeric substrates were used to provide a permeable membrane for the transport and removal of gaseous electrolysis products generated at the electrodes. Electroosmotic flow between interdigitated electrodes was demonstrated and provided electric field-free pumping of fluids in sections of the channel outside of the electrode pairs. The resultant pumping velocities were shown to be dependent on the applied voltage, not on the applied field strength, and independent of the length of the electroosmotically pumped region.
Subject(s)
Electrodes , Electrochemistry/instrumentation , OsmosisABSTRACT
A microchip device was demonstrated that integrated enzymatic reactions, electrophoretic separation of the reactants from the products and post-separation labeling of proteins and peptides prior to detection. A tryptic digestion of oxidized insulin B-chain was performed in 15 min under stopped flow conditions in a heated channel, and the separation was completed in 1 min. Localized thermal control of the reaction channel was achieved using a resistive heating element. The separated reaction products were then labeled with naphthalene-2,3-dicarboxaldehyde (NDA) and detected by laser-induced fluorescence. A second reaction at elevated temperatures was also demonstrated for the on-chip reduction of disulfide bridges using insulin as a model protein. This device represents one of the highest levels, to date, of monolithic integration of chemical processes on a microchip.
Subject(s)
Peptides/chemistry , Proteins/chemistry , Hydrolysis , Miniaturization , Naphthalenes/chemistry , Peptides/isolation & purification , Proteins/isolation & purification , SemiconductorsABSTRACT
An integrated system for rapid PCR-based analysis on a microchip has been demonstrated. The system couples a compact thermal cycling assembly based on dual Peltier thermoelectric elements with a microchip gel electrophoresis platform. This configuration allows fast (approximately 1 min/ cycle) and efficient DNA amplification on-chip followed by electrophoretic sizing and detection on the same chip. An on-chip DNA concentration technique has been incorporated into the system to further reduce analysis time by decreasing the number of thermal cycles required. The concentration injection scheme enables detection of PCR products after performing as few as 10 thermal cycles, with a total analysis time of less than 20 min. The starting template copy number was less than 15 per injection volume.
