Our ultimate goal is to develop a new and simple method to microencapsulate drugs and other bioactive substances, particularly biomacromolecules such as proteins and peptides, in biodegradable controlled-release polymers. Current methods of microencapsulation in polymers such as poly(lactic-co-glycolic acid) (PLGA) suffer from: a) protein instability including use of protein-denaturing organic solvents, b) expensive large-scale, aseptic processing for encapsulation of each peptide/protein of interest, and c) the inability of clinicians at the point-of-care or other non formulation scientists in the field to effectively perform encapsulation. We will exploit our novel finding of spontaneous PLGA pore closing to microencapsulate proteins and peptides by: creating polymer delivery systems with defined pore networks, placing the polymers in the presence of an aqueous drug solution of interest, and then causing the pore network to close, e.g., by simple heating to physiological temperature. Unlike the vast majority of microencapsulation methodologies, which place drug in contact with dissolved polymer before or during microencapsulation, this approach creates a new paradigm in microencapsulation, whereby the biomaterial system is initially created and then microencapsulation is performed at the very end of preparation. In a sense, the polymer pore network microencapsulates by """"""""itself"""""""" spontaneously-hence the term, """"""""self-microencapsulation."""""""" Moreover, microencapsulation a) takes place under nondenaturing conditions without the need for organic solvent, b) could be done inexpensively with terminally sterilized porous PLGA microspheres for multiple peptides and/or proteins, c) would be applicable to numerous polymer configurations and geometries such as microspheres, nanospheres, tissue engineering scaffolds, drug-eluting stents, and d) could be performed by clinicians and investigators in the field, since encapsulation is by simple aseptic mixing of protein and polymer. This proposal will test the hypothesis that PLGA microspheres entrapping high loading of protein or peptide drugs can be prepared reproducibly by self-microencapsulation, and the resulting polymer will exhibit excellent drug stability and release performance both in vitro and in vivo. This hypothesis will be tested in 3 specific aims: 1) determine the effect of formulation variables on self- microencapsulation of model proteins, 2) investigate the mechanism of spontaneous pore closing in aqueous media, and 3) test the feasibility of self-encapsulation to stabilize and control the release of therapeutic peptides and proteins in vitro and in vivo.

Public Health Relevance

This project tests the feasibility of a brand new method of microencapsulation based on a recent finding from our group demonstrating how biodegradable polymers can heal their tiny holes and cracks spontaneously in water. The microencapsulation method does not use organic solvents and could have far reaching applications to the slow delivery of the important biomacromolecular class of drugs and vaccine antigens from injectable depots, tissue engineering scaffolds, and drug-eluting stents.

National Institute of Health (NIH)
National Institute of Biomedical Imaging and Bioengineering (NIBIB)
Exploratory/Developmental Grants (R21)
Project #
Application #
Study Section
Gene and Drug Delivery Systems Study Section (GDD)
Program Officer
Henderson, Lori
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Michigan Ann Arbor
Schools of Pharmacy
Ann Arbor
United States
Zip Code
Bailey, Brittany A; Desai, Kashappa-Goud H; Ochyl, Lukasz J et al. (2017) Self-encapsulating Poly(lactic-co-glycolic acid) (PLGA) Microspheres for Intranasal Vaccine Delivery. Mol Pharm 14:3228-3237
Bailey, Brittany A; Ochyl, Lukasz J; Schwendeman, Steven P et al. (2017) Toward a Single-Dose Vaccination Strategy with Self-Encapsulating PLGA Microspheres. Adv Healthc Mater 6:
Huang, J; Mazzara, J M; Schwendeman, S P et al. (2015) Self-healing of pores in PLGAs. J Control Release 206:20-9
Shah, Ronak B; Schwendeman, Steven P (2014) A biomimetic approach to active self-microencapsulation of proteins in PLGA. J Control Release 196:60-70
Schwendeman, Steven P; Shah, Ronak B; Bailey, Brittany A et al. (2014) Injectable controlled release depots for large molecules. J Control Release 190:240-53
Sophocleous, Andreas M; Desai, Kashappa-Goud H; Mazzara, J Maxwell et al. (2013) The nature of peptide interactions with acid end-group PLGAs and facile aqueous-based microencapsulation of therapeutic peptides. J Control Release 172:662-70
Desai, Kashappa-Goud H; Kadous, Samer; Schwendeman, Steven P (2013) Gamma irradiation of active self-healing PLGA microspheres for efficient aqueous encapsulation of vaccine antigens. Pharm Res 30:1768-78
Reinhold, Samuel E; Schwendeman, Steven P (2013) Effect of polymer porosity on aqueous self-healing encapsulation of proteins in PLGA microspheres. Macromol Biosci 13:1700-10
Mazzara, J M; Balagna, M A; Thouless, M D et al. (2013) Healing kinetics of microneedle-formed pores in PLGA films. J Control Release 171:172-7
Desai, Kashappa-Goud H; Schwendeman, Steven P (2013) Active self-healing encapsulation of vaccine antigens in PLGA microspheres. J Control Release 165:62-74

Showing the most recent 10 out of 11 publications