Comparison of different functionalization routes for the fabrication of enzyme-single wall carbon nanotube conjugates.

In this work, various methods to functionalize single wall carbon nanotubes with immobilized enzyme for bioanalytical application were investigated. Several different conjugation methods, including both covalent and noncovalent methodologies, were compared and the resulting enzyme loading and retained activity were evaluated. After enzymatic modification, the addition of amphiphilic molecules to aid in nanotube dispersability was also studies and its effect on enzyme activity determined.

Fabrication of high-capacity biomolecular carriers from dispersible single-walled carbon nanotube-polymer composites.

One of the most interesting applications for carbon nanotubes is as a support material for bioanalytical devices. In this work, we successfully used an ultraviolet light initiated "graft from" polymerization method to fabricate polymer functionalized carbon nanotubes (PFCNTs) with pendant chains of various functionalities, including poly(ethylene glycol) chains to boost dispersibility and pendant epoxy groups for protein conjugate sites. A model enzyme, alkaline phosphatase, was used to study biomolecule loading efficiency as well as the retention of enzyme activity.

Photopatternable Polymeric Membranes for Optical Oxygen Sensors.

A new class of optical oxygen sensor that can be photopatternable by traditional UV lithography is presented. They are fabricated using photopatternable spin-on silicone (polydimethyl-siloxane, PDMS) with oxygen sensitive luminescent dyes. It has a good adhesion property and can be applied on glass or on photopolymer (SU-8) without any additional surface treatments.

Enhanced wettability of SU-8 photoresist through a photografting procedure for bioanalytical device applications.

In this work, we detail a method whereby a polymeric hydrogel layer is grafted to the negative tone photoresist SU-8 in order to improve its wettability. A photoinitiator is first immobilized on freshly prepared SU-8 samples, acting as the starting point for various surface modifications strategies. Grafting of a 2-hydroxyethylmethacrylate-based hydrogel from the SU-8 surface resulted in the reduction of the static contact angle of a water droplet from 79 +/- 1 degrees to 36 +/- 1 degrees , while addition of a poly(ethylene glycol)-rich hydrogel layer resulted in further improvement (8 +/- 1 degrees ).