Dong Woog Lee

Articular cartilage is a highly efficacious water-based tribological system that is optimized to provide low friction and wear protection at both low and high loads (pressures) and sliding velocities that must last over a lifetime. Although many different lubrication mechanisms have been proposed, it is becoming increasingly apparent that the tribological performance of cartilage cannot be attributed to a single mechanism acting alone but on the synergistic action of multiple "modes" of lubricat

Chitosan, a load-bearing biomacromolecule found in the exoskeletons of crustaceans and insects, is a promising biopolymer for the replacement of synthetic plastic compounds. Here, surface interactions mediated by chitosan in aqueous solutions, including the effects of pH and contact time, were investigated using a surface forces apparatus (SFA). Chitosan films showed an adhesion to mica for all tested pH ranges (3.0-8.5), achieving a maximum value at pH 3.0 after a contact time of 1 h (Wad ~ 6.4

Stick-slip friction was observed in articular cartilage under certain loading and sliding conditions and systematically studied. Using the Surface Forces Apparatus, we show that stick-slip friction can induce permanent morphological changes (a change in the roughness indicative of wear/damage) in cartilage surfaces, even under mild loading and sliding conditions. The different load and speed regimes can be represented by friction maps--separating regimes of smooth and stick-slip sliding; damage

We fit the size distribution of liquid-ordered (L(o)) domains measured from fluorescence images of model cytoplasmic myelin monolayers with an equilibrium thermodynamic expression that includes the competing effects of line tension, λ, dipole density difference, Δm, and the mixing entropy. From these fits, we extract the line tension, λ, and dipole density difference, Δm, between the L(o) and liquid-disordered (L(d)) phases. Both λ and Δm decrease with increasing surface pressure, , although λ/Δ

The surface forces apparatus and atomic force microscope were used to study the effects of lipid composition and concentrations of myelin basic protein (MBP) on the structure of model lipid bilayers, as well as the interaction forces and adhesion between them. The lipid bilayers had a lipid composition characteristic of the cytoplasmic leaflets of myelin from "normal" (healthy) and "disease-like" [experimental allergic encephalomyelitis (EAE)] animals. They showed significant differences in the

Abstract The development of flexible electronic technology has led to convenient devices, including foldable displays, wearable, e‐skin, and medical devices, increasing the need for flexible adhesives that can quickly recover their shape while connecting the components of the device. Conventional pressure sensitive adhesives (PSAs) can improve recoverability via crosslinking, but often have poor adhesive strength. In this study, new types of urethane‐based crosslinkers are synthesized using m ‐x

The remarkable underwater adhesion of mussel foot proteins has long been an inspiration in the design of peptidomimetic materials. Although the synergistic wet adhesion of catechol and lysine has been recently highlighted, the critical role of the polymeric backbone has remained largely underexplored. Here, we present a peptidomimetic approach using poly(ethylene glycol) (PEG) as a platform to evaluate the synergistic compositional relation between the key amino acid residues (<i>i.e.</i>, DOPA