Self-Assembled Biodegradable Block Copolymers and DNA Lipoplexes as Potential Nanomedicines

CHEMS Seminar

Featuring Lei Zhu, Ph.D.
Associate Professor, Polymer Program
Institute of Materials Science and Department of Chemical, Materials and Biomolecular Engineering
School of Engineering
University of Connecticut

Location:  McDonald Douglas Auditorium (MDEA)

Polymeric nanoparticle formation via self-assembly is an attractive approach for delivery systems. In this presentation, we focus on two self-assembled polymer and biopolymer systems, namely, biodegradable block copolymers and DNA lipoplexes. In the first system, incompatible blends of poly(ethylene oxide)-/b/-poly(L-lactide) (PEO-PLLA) and poly(ethylene-/co/-butene)-/b/-poly(D-lactide) (PEB-PDLA) were studied. Stereocomplexation between biodegradable PLLA and PDLA induced intriguing phase morphologies. When the molecular weight of PEB (4.2k) was higher than that of PEO (2k), inverted honeycomb cylindrical morphology was observed in the melt, whereas biomimetic onion-like crystals were obtained in the solid-state. We believe that noncentrosymmetric lamellar morphology was responsible for the onion crystal formation, which was induced by unbalanced surface stresses at basal planes of the stereocomplex lamellar crystals. In the second system, synthetic cationic lipids having various molecular shapes were used to complex with double-stranded DNA. When the shape of the lipid tails changed from rod-like (cyanobiphenyl), to discotic (triphenylene), and finally to cubic [polyhedral oligomeric silsesquioxane (POSS)], the liquid crystalline structures of the DNA lipoplexes transformed from lamellar to inverted hexagonal. We attributed this change to the negative curvature of the POSS imidazolium lipid. Potential applications for biomimetic onion crystals and organic/inorganic DNA nanocomposites may be controlled drug and gene delivery.

About the Speaker:
Lei Zhu received his B.S. degree in materials chemistry in 1993 and his M.S. degree in polymer chemistry and physics in 1996 from FudanUniversity. He received his Ph.D. degree in polymer science from the University of Akron in 2000. After two-year postdoctoral experience at the Maurice Morton Institute, University of Akron, he joint the Institute of Materials Science and Department of Chemical, Materials and Biomolecular Engineering at the University of Connecticut as an assistant professor.  In 2007, he was awarded tenure and promoted to associate professor. His research interests include supramolecular self-assembly of discotic liquid crystals, organic-inorganic hybrid nanomaterials for capacitor applications, development of artificial antibody as nanomedicines, and polyelectrolyte membrane fuel cells. He is recipient of NSF Career Award, 3M Non-tenured Faculty Award, DuPont Young Professor Award, and Rogers Teaching Excellence Award. He is author and co-author of 57 refereed journal publications, three book chapters, and numerous conference proceedings. He delivered 35 invited talks and 65 contributed presentations.  He has over 1,000 citations.