Francis Moussy

Dexamethasone/PLGA microspheres for continuous delivery of an anti-inflammatory drug for implantable medical devices

The purpose of this research was to develop polylactic-co-glycolic acid (PLGA) microspheres for continuous delivery of dexamethasone for over a 1-month period, in an effort to suppress the acute and chronic inflammatory reactions to implants such as biosensors, which interfere with their functionality. The microspheres were prepared using an oil-in-water emulsion technique. The oil phase was composed of 9:1 dichloromethane to methanol with dissolved PLGA and dexamethasone. Some microspheres were predegraded for 1 or 2 weeks. Ten percent of polyethylene glycol was added to the oil phase in alternative formulations to delay drug release. The in vitro release studies were performed in a constant temperature (37 C) warm room, in phosphate-buffered saline at sink conditions. Drug loading and release rates were determined by HPLC-UV analysis. The standard microsphere systems did not provide the desired release profile since, following an initial burst release, a delay of 2 weeks occurred prior to continuous drug release. Predegraded microspheres started to release dexamethasone immediately but the rate of release decreased after only 2 weeks. A mixed standard and predegraded microsphere system was used to avoid this delay and to provide continuous release of dexamethasone for 1 month.

Implantable biosensor telemetry and interface using an optocoupler

This paper details the development of a miniature electronics package for implantable amperometric glucose sensors. The package includes a potentiostat to bias the glucose sensor with the proper excitation voltage, a transimpedance amplifier to develop voltage level data from sensor current, and an optocoupler device to interface to a commercially available telemetry unit which then transmits the glucose concentration data to a receiver and data collection computer. Instrumentation described in this paper will allow other researchers to easily develop a miniaturized implantable potentiostat/telemetry unit for their own sensor applications.