(475g) Study of Targeted Particulate Adhesion to Cellulose Surfaces Mediated by Bifunctional Fusion Proteins

In considering the adhesion of functionalized particles to surfaces, the role of several features contributing to the interplay between hydrodynamics, surface forces and specific interactions can be sorted out through a hierarchy of interfacial and hydrodynamic flow experiments.

In this paper, we report on the direct measurements on a molecular system designed to allow targeted deposition and binding of particles to cellulose. This system involves a family of heterobifunctional fusion proteins that bind to both a red dye and to cellulose with various affinities. Amine-coated particles are labeled with a red dye, and the fusion protein is attached to these particles in various number densities. The strength of adhesion of a single particle to a cellulose fiber is measured by using micropipette aspiration as a function of adhesive affinity and specificity of the protein, its surface density and contact time. In addition, the dynamics of adhesion of the functionalized particles to cellulose-coated glass slide under controlled hydrodynamic flow is explored using flow chamber assays for two scenarios: detachment of bound particles, and attachment of particles in suspension, as a function of shear rate in addition to above mentioned parameters. Highly specific adhesion is observed in both studies, with a strong dependence on all of the operating variables. The force of adhesion was ~ 2 nN for the particles that were fully functionalized with bifunctional protein with the frequency of adhesion > 90% in micropipette aspiration experiments, while average force required to detach a bound particle was ~ 125 pN in flow chamber assays.