AVS 62nd International Symposium & Exhibition
    Biomaterial Interfaces Wednesday Sessions
       Session BI-WeM

Paper BI-WeM6
Physisorption of Stimuli-Responsive Polypeptides with Genetically Programmable Aqueous Phase Behavior

Wednesday, October 21, 2015, 9:40 am, Room 211D

Session: Biomolecules at Interfaces
Presenter: Linying Li, Duke University
Authors: L. Li, Duke University
C. Mo, Duke University
Q. Tu, Duke University
N.J. Carroll, Duke University
A. Chilkoti, Duke University
S. Zauscher, Duke University
M. Rubinstein, University of North Carolina at Chapel Hill
G.P. López, Duke University
Correspondent: Click to Email
The ability to control the physical adsorption (physisorption) of proteins to solid surfaces is of fundamental importance in the design of engineered bio-interfaces for many biomaterial, industrial and bioanalytical applications. We present a study of the kinetics of adsorption and consequent single- and multi-layered architectures of recombinant, intrinsically disordered proteins whose aqueous phase behavior is programmable at the sequence level. Elastin-like polypeptides (ELPs) are a class of engineered repetitive polypeptides that undergo a reversible, lower critical solution temperature (LCST) phase transition in water. Their phase behavior is programmable by tuning the amino acid sequence, concentration, and molecular weight of the ELPs. We used light scattering assays to investigate the phase diagrams of the peptides and quartz crystal microbalance with energy dissipation (QCM-D) to investigate the diffusion-limited adsorption kinetics of ELPs onto surfaces. Below the critical temperature, ELPs are soluble and only form single monolayers of peptides on surfaces upon adsorption, while above the critical temperature, ELPs phase separate, leading to multilayer adsorption. We used ellipsometry and atomic force microscopy (AFM) to characterize the thickness and roughness of the protein assemblies on surfaces. The elemental composition of the protein-modified surfaces was analyzed by X-ray photoelectron spectroscopy (XPS). Contact angle measurements were performed to examine the temperature-responsive nature of the surfaces. This study demonstrates that, based on their genetically encoded phase behaviors, the adsorption behavior of ELPs can be controlled to attain desired architecture, thermal-responsive behavior and functionality. It also provides insight into protein adsorption at the molecular level that can be useful in a number of contexts including immunoassays, drug delivery and cell culture.