Protein adsorption in static microsystems: effect of the surface to volume ratio

Abstract

A numerical model for the adsorption kinetics of proteins on the walls of a microchannel has been developed using the finite element method (FEM) to address the coupling with diffusion phenomena in the restricted microchannel volume. Time evolutions of the concentration of one species are given, both in solution and on the microchannel walls. The model illustrates the adsorption limitation sometimes observed when the microdimensions of these systems induce a global depletion of the bulk solution. A new non-dimensional parameter is introduced to predict the final value of the coverage of any microsystem under static adsorption. A working curve and a criteria (h/KC max . 10) are provided in order to choose, for given adsorption characteristics, the value of the volume-to-surface ratio (i.e. the channel height h) avoiding depletion effects on the coverage (relative coverage greater than 90% of the theoretical one). Simulations were compared with confocal microscopy measurements of IgG antibody adsorption on the walls of a PET microchannel. The fit of the model to the experimental data show that the adsorption is under apparent kinetic control.

Investigating the Kinetics of Antibody Adsorption onto Polyethylene Terephthalat (PET) Modified with Gold Nanoparticles in Flow Microchannel

“…Linearization using eq (7) in Figure 5B leads [21,24]. These mentioned values are all lower than that found for PET modified with NPs.…”

A Cell Programmable Assay (CPA) chip

“…For example, one must keep in mind that adsorption and absorption can significantly affect concentrations of reagents and can require optimization to achieve similar results to macroscale assays. 29 Similar considerations can also affect cell culture. [30][31][32] …”

Magnetic track array for efficient bead capture in microchannels

“…The density and magnetic permeability of the ink were determined. The density of 4.9679 g/cm 3 was measured with a helium pycnometer on the cured ink. The mass magnetization of the ink was measured with a SQUID as a function of the field at 300 K. (Supporting information S2) The resulting value of dimensionless magnetic permeability was 4.07.…”

“…Solid support may consist of particles or beads made from plastic, silica or glass, and magnetic materials. Protein adsorption in polymer microchannels [2] and its dynamic under stopped flow and continuous flow have been previously investigated in our lab [3,4]. Alternatively, magnetic beads were also used as solid-phase support to develop magnetic bead-based immunoassay both in microchip for biosensing and in capillary for immunoaffinity capillary electrophoresis (IA-CE) [5][6][7].…”