This is an on-going project in collaboration with Dr. Whitten’s group at the University of New Mexico (UNM). In this project, PPE-type conjugated polymers are grafted on a surface of silica particles. Two grafting methods are available: “graft-from” and “graft-on.” In the “graft-from” approach, the surface of the particles are modified with grafting points (iodobenzene) and polymer brushes are grown from there via in situ polymerization. In “graft-on” approach, the surface of the particles are modified with amino-functional groups.

Polymers are synthesized separately and the terminal of the polymer chains are functionalized with carboxyl functional groups. Then, polymer brushes are attached onto the surface through amide bonds via DCC/DMAP chemistry. These colloids with surface grafted polyelectrolytes retain the fluorescence ability of the polymer as shown in the confocal microscopy image. The presence of the polymers can also be observed in the SEM image.

Quenching experiments using a cyanine dye shows very efficient amplified quenching effect that is characteristic of conjugated polyelectrolyte. Possible applications of such particles include quantum dots and fluorescent sensors. At UNM, these particle are currently investigated for possible applications in light-activated bactericides.

Reference:
Ogawa, K; Chemburu, S.; Lopez, G.P.; Whitten, D.G.; Schanze, K.S. “Conjugated Polyelectrolyte-Grafted Silica Microspheres.” Langmuir 2007, 23, 4541-4548.