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

Abstract

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 < 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.

Incorporating Fluorescent Nanomaterials in Organically Modified Sol-Gel Materials – Creating Single Composite Optical pH Sensors

“…The triangulenium based pH-sensitive DAOTA dyes, 13,69 and the sol-gel synthesis of the sensor material is reported in our previous work. 3,18,43 Previous work reports on sensors with dyes that have a triethoxysilane group in their structure, which covalently bind the dye to the silicate network of the ORMOSIL. Here, we use a pH-responsive DAOTA dye (Figure S1) that physisorbs in the ORMOSIL material.…”

“…The approach based on organically modified silicate materials are more robust, 18 and we hope to be able to use the sensor material reported here to incorporate not only molecular dyes, but also more complex fluorescent materials. 49,[59][60][61] dimethoxyquinacridinium hexafluorophosphate (DMQA) were synthesized as previously reported.…”

“…[2][3][4][5][6] There are clear advantages of optical sensors, [7][8][9][10][11][12] but complications regarding calibration: optical pH sensors report optical signals fitting to a sigmoidal curve where the response range depends on the pKa of the pH-sensitive dye, [13][14] and a limited stability of the sensor material have reduced their industrial applicability. [15][16][17] We have recently reported a new sensor material for optical sensors, 18 and the first high performance pH sensor using this matrix. 3 One unresolved issue with this sensor design is the reference dyes or lipophilic sensor dyes cannot be incorporated into the matrix, without compromising performance.…”

“…21,40 We have described an organically modified silicon sol-gel that solves many of these issues, when it comes to creating a competitive optical pH sensor. 3,18,[41][42][43] The resulting sensor material has good chemical, photochemical and thermal stability as well as fast diffusion of H + , while excluding all other ions. The sensor material has the capacity to fully encapsulate the pH responsive dye, the ability to firmly stick to polymer and glass substrate, a long shelf-life and is fully biocompatible.…”

Investigating the Time Response of an Optical pH Sensor Based on a Polysiloxane–Polyethylene Glycol Composite Material Impregnated with a pH-Responsive Triangulenium Dye

“…17,23 We recently described our optimized sensor chemistry for determining pH, 17 with pH responsive diazaoxa-triangulenium (DAOTA) dye covalently linked in an ORMOSIL matrix. 16,17,26−28 The change in the fluorescence intensity of the responsive DAOTA emitter is converted into an optical sensor signal with reference to the emission from a nonresponsive dye.…”