Selective deposition of biocompatible sol-gel materials

An aqueous sol- gel route has been developed for electrochemically controlled deposition onto micro and nanofabricated electrodes. TEOS and MeTEOS were hydrolyzed under acidic conditions, and alcohol products were removed by distillation. The resulting clear sol has a hydrolysis ratio between 40 and 45. Following hydrolysis, pH was raised to 5.0 with addition of potassium hydroxide. At room temperature, this sol is stable for approximately 30 min. Gelation can be electrochemically induced at cathodic surfaces by locally increasing pH. Films of significant thickness and durability have been formed within seconds of deposition at - 1.0 V. Selective deposition has been demonstrated on platinum microelectrodes. Furthermore, proteins and other biological species can be incorporated into this aqueous route due to mild pH, ionic, and temperature conditions. Proteins such as bovine serum albumin have been successfully entrapped in electrodeposited gel, while smaller molecules such as fluorescein have been observed to diffuse through the pores. This sol- gel electrodeposition process is ideal for device fabrication, particularly in the field of electrochemical biosensors.