With the development of nanotechnology, great progress has been made in the fabrication of nanochannels. Nanofluidic biochips based on nanochannel structures allow biomolecule transport, bioseparation, and biodetection. The domain applications of nanofluidic biochips with nanochannels are DNA stretching and separation. In this Review, the general fabrication methods for nanochannel structures and their applications in DNA analysis are discussed. These representative fabrication approaches include conventional photolithography, interference lithography, electron-beam lithography, nanoimprint lithography and polymer nanochannels. Other nanofabrication methods used to fabricate unique nanochannels, including sub-10-nm nanochannels, single nanochannels, and vertical nanochannels, are also mentioned. These nanofabrication methods provide an effective way to form nanoscale channel structures for nanofluidics and biosensor devices for DNA separation, detection, and sensing. The broad applications of nanochannels and future perspectives are also discussed.

Surface-grafted, environmentally responsive polymers have shown great promise for controlling adsorption and desorption of macromolecules and cells on solid surfaces. In the paper, we demonstrate that certain mixed self-assembled monolayers (SAMs) of oligo(ethylene glycol) (OEG) and methyl-terminated alkanethiolates on gold form surfaces with switchable hydrophobicity and tendency for protein adsorption and cellular attachment. At temperatures above 32 degrees C, SAMs with a surface density of approximately 50% OEG adsorbed significant amounts of pyruvate kinase and lysozyme, whereas below this temperature, these same SAMs were resistant to the adsorption of these proteins. Furthermore, protein layers adsorbed to these SAMs above 32 degrees C were removed upon rinsing with water below this temperature. Similar results were seen for attachment and release of the marine bacterium, Cobetia marina. The change from nonresistance to adsorptive state of the SAMs was concomitant with a change in advancing water contact angle. Vibrational sum frequency generation spectroscopy suggests that the temperature-induced changes coincide with a disorder-to-partial order transition of the hydrated methylene chains of the OEG moieties within the SAMs. Mixed OEG-methyl SAMs represent both a convenient means of controlling macromolecular and cellular adsorption within the laboratory and a useful tool for relating adsorption properties to molecular structures within the SAMs.

No abstract

We describe a new, direct electrochemical means of detecting biorecognition at modified electrodes. Ternary self-assembled monolayers (SAMs) were formed on gold electrodes by coadsorption of biotin, viologen, and oligo(ethylene glycol)-functionalized alkanethiols. These SAMs exhibit electroactivity of the viologen moieties, biospecificity of the biotin moieties, and inhibition of nonspecific adsorption by the oligo(ethylene glycol) moieties. Changes in electrochemical behavior of the immobilized viologen observed by cyclic voltammetry accompanying biospecific adsorption of an anti-biotin antibody to biotin can be used to transduce biorecognition on the surface rapidly and reproducibly. Surface plasmon resonance measurements are consistent with the electrochemical responses that result from the partially reversible adsorption of the antibody to the SAM surface.

Quantification of the intensity and linewidth of the ν(CN) IR band in a series of neutral and anionic nitrile-functionalized oligophenylenes reveals that the CN vibration is coupled to nuclear and electronic structural changes.

A new viologen derivative of N-(n-octy1)-N'-( 10-mercaptodecy1)-4,4'-bipyridinium dibromide has been prepared and characterized by elemental analysis, IR, 'H NMR, MS and TG-DTA. X-Ray photoeIectron spectroscopy, cyclic voltammetry and chronoamperometry have been used to characterize the monolayers formed by this compound on the bulk gold electrodes by selfassembly.

No abstract

No abstract