Kathleen J Leach

US Patent:

6528035, Mar 4, 2003

Filed:

Nov 6, 2000

Appl. No.:

09/707440

Inventors:

Edith Mathiowitz - Brookline MA
Jules S. Jacob - Taunton MA
Kathleen Jo Leach - Midland MI

Assignee:

Brown University Research Foundation - Providence RI

International Classification:

B32B 516

US Classification:

423407

Abstract:

Two or more hydrophilic polymers that are not soluble in each other at a particular concentration and temperature, but which have a positive spreading coefficient in solution, are used to form multi-layered polymeric microspheres. The multi-layer microspheres produced by the method are distinguished by extremely uniform dimensioned polymer layers and actual incorporation of a substance to be delivered into the polymer layers. In the preferred embodiment of the method, two polymers are dissolved in an aqueous solvent, the substance to be incorporated is dispersed or dissolved in the polymer solution, the mixture is suspended in an organic solvent or polymer/water mixture and stirred, and the solvent is slowly evaporated, creating microspheres with an inner core formed by one polymer and an outer layer formed by the second polymer.