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Avraham Halperin

Soft Matter Theory Motivated by Biotechnology Applications

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Biotechnology presents a rich variety of problems at the interface between biology, medicine, soft matter physics and materials science. We address the under-explored theory of such systems. The issues include biocompatibility, biological essays, drug delivery etc. One illustrative example concerns the tuning of protein adsorption on surfaces.

Repressing protein adsorption is important in a wide variety of situations among them improving the signal to noise ratio in immunoassays, elimination of biofilm from catheters and improving the biocompatibility of materials in general. It is often accomplished by utilizing brushes of Polyethylene glycol (PEG). Similar physics play a role in the formulation of drugs as exemplified by PEGylated protein drugs or Stealth Liposomes. In other situations, such as harvesting cell sheets or protein chromatography, it is desirable to “switch” the adsorption on and off by a small change in Temperature pH etc. This is often accomplished using thermoresponsive brushes of end grafted PNIPAM. Polymer motifs play an important role in all of these examples and one research theme concerns the interactions between proteins and polymers. Other research directions include dendrimers, two state model of neutral water-soluble polymers, the physical chemistry of DNA micoarrays and renal clearance of macromolecules. We explore such problems utilizing phenomenological theory in combination with computer simulations

Some Recent Publications

Theory of Colloid - Brush Interactions

A. Halperin, G. Fragneto , A. Schollier and M. Sferrazza, Primary vs. Ternary Adsorption of Proteins onto PEG Brushes Langmuir 23, 10603 (2007)
V. Ermilov, A. Lazutin and A. Halperin Colloids in Brushes : The Insertion Free Energy via Monte Carlo Simulation with Umbrella Sampling Macromolecules, 43, 3511 (2010)

Theory of DNA Micro-arrays

A. Halperin , A. Buhot and E.B. Zhulina On the Hybridization Isotherms of DNA Microarrays : The Langmuir Model and its Extensions Journal of Physics Condensed Matter 18, S463 (2006).
A. Halperin , A. Buhot and E.B. Zhulina Hybridization at a Surface : The Role of Spacers in DNA Microarrays Langmuir 22, 11290 (2006)


Y. Guo, J. van Beek, B. Zhang, M. Colussi, P. Walde, A. Zhang, M. Kröger, A. Halperin, A.D. Schlüter Tuning Polymer Thickness : Synthesis and Scaling Theory of Homologous Series of Dendronized Polymers Journal of the American Chemical Society 131, 11841 (2009)
M. Kröger, O. Peleg and A. Halperin From Dendrimers to Dendronized Polymers and Forests : Scaling Theory and its Limitations Macromolecules 43, 6213 (2010)

Two State Polymers

N. Yoshinaga, D.J. Bicout, E.I. Kats and A. Halperin Dynamic Core Shell Structures in Two State Models of Neutral Water Soluble Polymers Macromolecules 40, 2201 (2007)
N. Yoshinaga, E.I. Kats and A. Halperin, On the Adsorption of Two-State Polymers, Macromolecules 41, 7744 (2008)