Viscoelastic properties of adsorbed and cross-linked polypeptide and protein layers at a solid–liquid interface

Inhibitory effect of common microfluidic materials on PCR outcome

“…Although AFM works at ambient temperature, even in liquid the surface is visualized only over a very small area [7,8,[10][11][12]. FTIR is suitable only for micro-samples, allowing the molecular bond and grouping vibrations to be deducted [7,[13][14][15][16].…”

Surface Interactions of Monoclonal Antibodies Characterized by Quartz Crystal Microbalance with Dissipation: Impact of Hydrophobicity and Protein Self-Interactions

“…QCM-D can be used to study how such properties are impacted by both the intrinsic properties of the molecule and the solution conditions. [11][12][13][14][15][16] In QCM-D, the sensor, an AT-cut piezoelectric quartz crystal, is oscillated in shear mode at its fundamental resonant frequency and its overtones, by passing an alternating current through the crystal. Information about the adsorption process is obtained by the simultaneous measurement of changes in the resonance frequency ( f N ) and the dissipation factor ( D N ) at each Nth overtone of the sensor crystal.…”

“…17 The thickness and viscoelastic properties of the film are modeled by applying the Voigt viscoelastic model [18][19][20] to analyze the measured parameters. [12][13]21 For rigid films displaying little shift in dissipation, the change in the resonance frequency, f N , is proportional to the change in the total adsorbed surface mass as described by the Sauerbrey equation. [22][23] The mass or thickness determined by QCM-D includes solvent that is either bound to or hydrodynamically coupled to the adsorbing protein film.…”

“…An evaluation of the mass, viscoelastic properties, and the reversibility of the adsorbed protein layer can lead to an understanding of the interactions of protein molecules with the surface as well as protein-protein interactions at the surface. [9][10][11][12][13][14][15][16]23,24 QCM-D can be used to study how such interactions are impacted by solution conditions (e.g., pH, buffer, and ionic strength) or the presence of excipients commonly used in therapeutic protein formulations.…”

Protein adsorption behaviors on chitosan/poly(ɛ-caprolactone) blend films studied by quartz crystal microbalance with dissipation monitoring (QCM-D)

“…To evaluate the viscoelasticity of an adsorbed protein layer, the specific dissipation shift was defined as the ratio between normalized frequency and dissipation sift (|∆D/(∆f/n)|), which means the induced energy dissipation per coupled unit mass, since the |∆D/(∆f/n)| ratio directly reveals the influence of the protein adsorption on the viscoelastic damping of the crystals resonance [16] . It is clear that a low |∆D/(∆f/n)| value indicates mass addition without significant dissipation increase, which is the characteristic of a rigid layer, while a large |∆D/(∆f/n)| value can be ascribed to a soft, dissipative layer.…”