Abstract
<jats:p>The nitroxide TEMPOL is a small amphiphilic molecule. SolGel is a porous, colloidal solid in a liquid phase with particle size reported in the range of 2 nanometers to 0.2 micrometers. Based on these known characteristics, several possibilities exist, each one predictive of varying degrees of TEMPOL release from or entrapment in SolGel. In the first case, TEMPOL is a small molecule. Small molecules are known to pass easily in and out of SolGel via convection and diffusion. In the second case, TEMPOL is amphiphilic. It is predicted that, in a hydrophilic solution, amphiphiles will form micelles, or microspheres to maintain the lowest free energy. Formation of micelles within the SolGel may allow the TEMPOL to remain embedded for a longer period of time, eventually becoming entrapped with aging of SolGel. Depending on the size of micelle formed, it may or may not still pass through the pores of SolGel. This could be advantageous, creating a form of delay release formulation. Stability of SolGel and Tempol retention may be affected by various factors, including pH of surrounding environs, internal pH during synthesis of SolGel, and aging of SolGel. In this preliminary investigation, characterization of Tempol release from TMOS SolGel was performed, taking in to account each of these three factors.</jats:p>