A process for forming microspheres is disclosed. The process includes: forming a first plurality microspheres comprising at least one bioactive agent and modified cellulose； contacting the first plurality of microspheres with a solution of a biodegradable polymer to form a discontinuous phase liquid； contacting the discontinuous phase liquid with a continuous phase liquid to form an emulsion； and extracting a second plurality of microspheres from the emulsion, the second plurality of microspheres comprising the first plurality of microspheres.
