Biocompatible Microporous Organically Modified Silicate Material with Rapid Internal Diffusion of Protons

A new four-component organically modified silicate (ORMOSIL) material was developed with optical pH sensors in mind. Through a sol gel process, the porosity of an ORMOSIL framework was optimized to allow rapid diffusion of protons, ideal for fast response to pH in an optical sensor. The optically transparent material was produced by catalyzing the dual polymerization of 3-(glycidoxy)propyltrimethoxysilane (GPTMS) and propyltriethoxysilane (PrTES) with boron trifluoride diethyl etherate. The performance of the resulting material in fluorescence based optical pH sensors was evaluated by incorporation of active dye components in the inorganic polymer framework. It is demonstrated that the material has a short response time (t(90) < 30 s) and high stability in medium and during storage, and resulting sensor spots are biocompatible. It is concluded that this ORMOSIL material has excellent properties for optical pH sensors.