EFFECTS OF POLY(ETHYLENE GLYCOL) DOPING ON THE BEHAVIOR OF PYRENE, RHODAMINE 6G, AND ACRYLODAN-LABELED BOVINE SERUM-ALBUMIN SEQUESTERED WITHIN TETRAMETHYLORTHOSILANE-DERIVED SOL-GEL-PROCESSED COMPOSITES

We investigate the effects of controlled poly(ethylene glycol) (PEG) d oping on the behavior of pyrene, rhodamine 6G (R6G), and acrylodan-lab eled bovine serum albumin (BSA-Ac) sequestered within tetramethyiortho silicate (TMOS)-derived sol-gel-processed materials. To probe the dipo larity of the local environment within the composite we performed stat ic fluorescence measurements on pyrene as the composites aged. We foun d that small levels of PEG loading effected significant enhancements i n the local dipolarity surrounding the average pyrene molecule. Time-r esolved fluorescence anisotropy measurements were used to follow the r otational reorientation dynamics of R6G as the composites aged. As the PEG loading increased, the R6G reorientational mobility increased. Ni trogen adsorption techniques were used to quantify the effects of PEG doping level on the surface area and final xerogel pore features. A la rge reduction in surface area was observed with PEG doping, but no det ectable change in pore size was noted. The effects of PEG doping on a biomolecule were probed by following the time-resolved fluorescence an isotropy decay of BSA-Ac. These results showed that PEG doping resulte d in increased biomolecule dynamics relative to that found for a neat, undoped TMOS-derived composites. Together these results show that PEG doping can be used to tune the sol-gel-processed composite dipolarity , alter the mobility of dopants sequestered within the composite, cont rol analyte acessibility to the sensing chemistry, and modulate the in ternal dynamics within a biodopant.