Daniel
A. Hammer, Ph.D.
hammer@seas.upenn.edu
Professor of Bioengineering
Professor of Chemical
Engineering
Member, Institute
of Medicine and Engineering
B.S.E., Chemical Engineering,
Princeton University, 1982
M.S.E, Chemical Engineering,
University of Pennsylvania, 1985
Ph.D., Chemical Engineering,
University of Pennsylvania, 1987
Research Interests
Cell adhesion:
We are interested in how cell adhesion is controlled by the physical
and chemical properties of cell surface molecules. Using biological
cells and molecules, well-defined adhesion assays, and computer
simulations, we are developing a comprehensive picture of how cell
adhesion molecules work. We have reconstituted adhesion molecules
from white cells onto polymeric spheres, retaining full molecular
activity.
Virus-cell interactions:
Our lab studies the fundamental factors that control viral infection,
especially membrane fusion, where the outer lipid bilayer of the
virus fuses with a membrane of the host cells. This fusion is mediated
by proteins on the viral surface. Our long-term goal is to reconstitute
the fusion activity of viral molecules into larger structure, using
artificial molecular fusion machines.
Polymersomes:
With collaborators, we have been able to make vesicles from diblock
copolymers. These vesicles, called "polymersomes" are tougher and
less permeable than phospholipid vesicles, and thus offer advantages
for drug delivery and encapsulation. We are working on making polymersomes
from new polymers and assessing biological applications of the resulting
structures.
Selected Publications
Hammer, D.A., and S.M.
Apte. "Simulation of Leukocyte Rolling and Adhesion on Surfaces
in Shear Flow: General Results and Analysis of Selectin-mediated
Neutrophil Adhesion"
Biophysical Journal 63:35-57
(1992).
Goetz, D.J., M. El-Sabban,
B.U. Pauli, and D.A. Hammer. "Dynamics of Neutrophil Rolling over
Stimulated Endothelium in vitro." Biophysical Journal 66; 2202-2209
(1994).
Alon, Ronen, D. A. Hammer
and Timothy A. Springer. "Lifetime of the P-selectin: Carbohydrate
Bond in Response to Force on Neutrophils in Hydrodynamic Flow" Nature
374:539-542 (1995).
Kuo, Suzanne C., D.A.
Hammer and Douglas A. Lauffenburger. "Simulation of the detachment
of specifically-bound particles from surfaces by shear flow", Biophysical
Journal 73:517-531 (1997).
Brunk, Debra K., Douglas
J. Goetz, and D.A. Hammer. "sialyl-Lewisx/E-selectin-mediated rolling
in a cell free system", Biophysical Journal 71:2902-2907 (1996).
Greenberg, Adam W.,
D.K. Brunk, and D.A. Hammer, (2000) "Cell-free rolling mediated
by L-selectin and sialyl-Lewisx reveals the shear threshold
effect", Biophysical Journal 79:2391-2402.
Chang, Kai-Chien and
D.A. Hammer. Adhesive dynamics simulations of sialyl-Lewisx mediated
rolling in a cell free system Biophysical Journal 79:1891-1902
(2000).
Discher, B., Y.-Y. Won,
D.S. Ege, J.C.-M. Lee, F.S. Bates, D.E. Discher and D.A. Hammer,
Polymersomes: tough vesicles made from block copolymers, Science
284:1143-1146 (1999).
Greenberg, A.W., W.G.
Kerr, and D.A. Hammer, Relationship between selectin-mediated rolling
of hematopoietic stem and progenitor cells and progression in hematopoietic
development, Blood 95:478-486 (2000).
Rodgers, Stephen D.,
Raymond T. Camphausen, and D.A. Hammer. (2000). Sialyl-Lewisx-Mediated,
PSGL-1-Independent Rolling Adhesion on P-selectin, Biophysical
Journal 79:694-706.
Chang, K.-C., D. F.J.
Tees, and D.A. Hammer. (2000) The State Diagram for Cell Adhesion
under Flow: Leukocyte Rolling and Firm Adhesion, Proceedings of
the National Academy of Sciences USA 97:11262-11267.
Bioengineering
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