Silica-based hybrid materials as biocompatible coatings for glucose sensors

The preparation of sol–gel silica-based biocompatible coatings, which can be used for future implantable glucose sensors is described. Tetraethylorthosilicate (TEOS) was used as precursor for water-borne silicate gels of which the properties were varied by mixing the sol with polyethylene glycol (SG-PEG), heparin (SG-HEP), dextran sulfate (SG-DS), nafion (SG-NAF) or polystyrene sulfonate (SG-PSS). The toxicity of the coatings was examined in vitro using human dermal fibroblasts. All materials showed to be non-toxic and the cell proliferation rate of fibroblasts was found to be dependent on the additive. Glucose measurements using glucose oxidase-based sensors coated with the different hybrid films were performed both in buffered solutions containing bovine serum albumin and in serum. Stable glucose responses were obtained for the coated sensors in both media. The SG-DS containing coating appeared to be most promising for future in vivo glucose measurements.