Simultaneous measurement of the maximum oscillation amplitude and the transient decay time constant of the QCM reveals stiffness changes of the adlayer

Abstract

Interpretation of adsorption kinetics measured with a quartz crystal microbalance (QCM) can be difficult for adlayers undergoing modification of their mechanical properties. We have studied the behavior of the oscillation amplitude, A(0), and the decay time constant, tau, of quartz during adsorption of proteins and cells, by use of a home-made QCM. We are able to measure simultaneously the frequency, f, the dissipation factor, D, the maximum amplitude, A(0), and the transient decay time constant, tau, every 300 ms in liquid, gaseous, or vacuum environments. This analysis enables adsorption and modification of liquid/mass properties to be distinguished. Moreover the surface coverage and the stiffness of the adlayer can be estimated. These improvements promise to increase the appeal of QCM methodology for any applications measuring intimate contact of a dynamic material with a solid surface.

Cell spreading on quartz crystal microbalance elicits positive frequency shifts indicative of viscosity changes

“…4, and ref. [37]). During the next 10-16 min, pressure on the quartz surface progressively decreased and accordingly, the frequency increased to levels between ∆f=-2 Hz and ∆f=-10 Hz (Fig.…”

“…Finally a frequency decrease corresponds either to an increase of adsorbed mass in the case of a thin and rigid adlayer, and/or to a softening of the adlayer, since it has been shown that the sensitivity in frequency increases for softer adlayers [48]. The QCM used here including the measured parameters, the physical properties, and the equivalent circuit model have been described in more detail elsewhere [37]. Briefly, under water loading a resolution of f±2 Hz, A 0 ±50 a.u.…”

“…We have recently developed a QCM device based on a transient technique, which detects mass and viscoelasticity changes in real time by periodically interrupting the quartz excitation and measuring the resonance frequency (f), the transient decay time constant (τ), and the maximal oscillation amplitude (A 0 ) [37].…”

A survey of the 2001 to 2005 quartz crystal microbalance biosensor literature: applications of acoustic physics to the analysis of biomolecular interactions

“…Early studies using QCM showed that the sensor's ability to detect changes in viscoelasticity or changes in the stiffness of the adlayer could provide information about cellular dynamics at surfaces (Marxer et al, 2003b). Further, sensors could be seeded with varying amounts of epithelial cells and growth monitored in real time, giving insight into the influence of cell-cell cooperativity in initial adhesion and spreading of cells (Fujisaki and Hattori, 2002;Marx et al, 2003).…”

“…adsorbed mass) provided insight about the mechanical/structural (viscoelastic) properties of the layer. In the same manner the adsorption kinetics of protein A, bovine serum albumin (BSA), immunoglobulin G (IgG), and fibronectin onto Ti and Au surfaces (Marxer et al, 2003a(Marxer et al, , 2003b, haemoglobin adsorption to mesoporous titanium oxide phytate films and phytic acid on tin-doped indium oxide electrodes (Paddon and Marken, 2004) and polypeptide adsoption to silica and Ti surfaces (Halthur and Elofsson, 2004) were characterized by QCM. In the latter case information about the energy losses at the interfacial layer was quantified from the maximal oscillation amplitude and the dissipation factor.…”