High-Q polymer-coated microspheres for immunosensing applications

Homogeneous polymeric thin layers have been used as functionalizing agents on silica microspherical resonators in view of the implementation of an immunosensor. We have characterized the microspheres functionalised with poly-L-lactic acid and Eudragit (R) L100, as an alternative to the commonly used 3-Aminopropyltrimethoxysilane. It is shown that polymeric functionalization does not affect the high quality factor (Q greater than 10(7)) of the silica microspheres, and that the Q factor is about 3x10(5) after chemical activation and covalent binding of immunogammaglobulin (IgG). This functionalizing process of the microresonator constitutes a promising step towards the achievement of an ultra sensitive immunosensor. (C) 2009 Optical Society of America