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Biomedical Engineering

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Peter J. Butler


230 Hallowell Building

University Park, PA 16802

Phone: 814-865-8086 / Fax: 814-863-0490


Personal Website:


Ph.D. Mechanical Engineering, 1998
The City University of New York, New York, NY

Research Interests

The research in Dr. Butler’s Cellular Mechanobiology Laboratory focuses on the fundamental molecular mechanisms by which vascular endothelial cells sense the forces from flowing blood and transduce this mechanical information into adjustments of cell and tissue biology. For example, Dr. Butler has found that the frictional force of blood flow, shear stress, results in a dilation of small arterioles and that the magnitude of this dilation depends on the rate of change of the shear stress. It is believed that arterioles use this rate-sensitivity to continually adjust blood flow to organs such as skeletal muscles during exercise. Shear stress is also important in the development of pathologies such as atherosclerosis and hypertension. Depending on spatial and temporal characteristics of the shear stress, endothelial cells adjust the expression of genes to adapt to their flow environment.

A major focus of Dr. Butler’s research is to elucidate the fundamental molecular mechanisms of mechanotransduction. To accomplish this goal, Dr. Butler, along with his students, have designed and built a confocal molecular dynamics microscope (CMDM) which allows nanosecond, and nanometer scale investigations of molecular dynamics in 3-dimensions in intact cells. This system uses time-resolved fluorescence microscopy to investigate the fluorescence lifetimes, rotations, diffusions, and transport of molecules at the cell surface, in the membrane, and in the cell cytoplasm.

Dr. Butler also co-Directs the Biomaterials and Bionanotechnology Summer Institute which provides summer research and educational opportunities for undergraduate and first year graduate students.

Selected Publications

Fuentes, Butler PJ. Coordinated Mechanosensitivity of Membrane Rafts and Focal Adhesions. Cellular and Molecular Bioengineering (24 February 2012), pp. 1-12 [abstract]

Fuentes, D.E., Bae, C. and Butler PJ. "Focal Adhesion Induction at the tip of a functionalized nanoelectrode." Cellular and Molecular Bioengineering. Volume 4, Number 4, 616-626 [abstract]

Muddana HS, Chiang HH, Butler PJ. Tuning membrane phase separation using nonlipid amphiphiles. Biophys J. 2012 Feb 8;102(3):489-97. Epub 2012 Feb 7.1. [abstract]

Muddana HS, Gullapalli RR, Manias E, Butler PJ. Atomistic simulation of lipid and DiI dynamics in membrane bilayers under tension. Physical Chemistry Chemical Physics. 2011; 13(4): 1368-1378. [abstract]

Tabouillot T, Muddana HS, Butler PJ. Endothelial cell membrane sensitivity to shear stress is lipid domain dependent. Cellular and Molecular Bioengineering. 2011 JUN; 4(2): 169-181. [abstract]

Muddana HS, Sengupta S, Mallouk TE, Sen A, Butler PJ. Substrate catalysis enhances single-enzyme diffusion. J Am Chem Soc. 2010 FEB 24; 132(7): 2110-+. [abstract]

Muddana HS, Morgan TT, Adair JH, Butler PJ. Photophysics of Cy3-encapsulated calcium phosphate nanoparticles. Nano Letters. 2009 APR; 9(4): 1559-1566. [abstract]

Bae C, Butler PJ. Finite element analysis of microelectrotension of cell membranes. Biomechanics and Modeling in Mechanobiology. 2008 OCT; 7(5): 379-386. [abstract]

Gullapalli RR, Demirel MC, Butler PJ. Molecular dynamics simulations of DiI-C(18)(3) in a DPPC lipid bilayer. Physical Chemistry Chemical Physics. 2008; 10(24): 3548-3560. [abstract]

Butler PJ, Dong C, Snyder AJ, Jones AD, Sheets ED. Bioengineering and Bioinformatics Summer Institutes: meeting modern challenges in undergraduate summer research. CBE Life Sci Educ. 2008 Spring;7(1):45-53. [Full text]

Dangaria JH, Butler PJ. (2007) Macrorheology and adaptive microrheology of endothelial cells subjected to fluid shear stress.  Am J Physiol Cell Physiol. Nov;293(5):C1568-75. Epub 2007 Aug 1 [abstract] [full text]

Bae C, Butler PJ.  (2007) Finite element analysis of microelectrotension of cell membranes.  Biomech Model Mechanobiol. Jul 27; [Epub ahead of print] [abstract] [full text]

Gullapalli RR, Tabouillot T, Dangaria J, Mathura R, Butler PJ.  (2007) Integrated multimodal microscopy, time resolved fluorescence, and optical-trap rheometry: toward single molecule mechanobiology.  Journal of Biomedical Optics.  Jan-Feb;12(1):014012 [Selected for special edition of Virtual Journal of Ultrafast Science] [abstract] [full text]

Ferko MC, Bhatnager AU, Garcia MB, Butler PJ. (2007). Finite-element stress analysis of a multicomponent model of sheared and focally-adhered endothelial cells.  Annals of Biomedical Engineering. 35(2):208-23 [abstract] [full text] [Erratum]

Dangaria J, Yang S, Butler PJ. (2007).  Improved nanometer-scale particle tracking in optical microscopy using microfabricated fiduciary posts.  BioTechniques. April. Volume 42, Number 4: pp 437-440 [abstract] [full text]

Ferko MC, Patterson BP, Butler PJ.  (2006). High-resolution solid modeling of biological samples imaged with 3-D fluorescence microscopy. Microscopy Research and Technique. 69(8):648-55 [abstract] [full text]

Bae C, Butler PJ. (2006). Automated single cell electroporation (aSCE). Biotechniques. 41(4):399-402 [abstract] [full text]

Li,S., Butler, P., Wang,Y., Hu,Y., Han, D.C., Usami,S., Guan,J.L., and Chien,S. (2002). The role of the dynamics of focal adhesion kinase in the mechanotaxis of endothelial cells. Proc. Natl. Acad. Sci. =U. S. A 99, 3546-3551. [Abstract] [Full Text]

Butler, P.J., Tsou,T.C., Li,J.Y., Usami,S., and Chien,S. (2001). Rate sensitivity of shear-induced changes in the lateral diffusion of endothelial cell membrane lipids: a role for membrane perturbation in shear-induced MAPK activation. FASEB J. 16(2), 216-8. [Abstract] [Full Text]

Butler ,P.J., Norwich ,G., Weinbaum,S., and Chien,S. (2001). Shear stress induces a time- and position-dependent increase in endothelial cell membrane fluidity. Am. J. Physiol Cell Physiol 280, C962-C969. [Abstract] [Full Text]

Butler ,P.J., Weinbaum,S., Chien,S., and Lemons,D.E. (2000). Endothelium-dependent, shear-induced vasodilation is rate-sensitive. Microcirculation. 7, 53-65. [Abstract] [Full text]