A combined reflectometry and quartz crystal microbalance with dissipation setup for surface interaction studies

Abstract

We have developed an instrument for surface interaction studies, which combines a newly invented four detector optical reflectometry setup with quartz crystal microbalance with dissipation (QCM-D) monitoring. The design is such that data from both techniques can be obtained simultaneously on the same sensor surface, with the same signal-to-noise ratio and time resolution, as for the individual techniques. In addition, synchronized information about structural transformations, molecular mass, and the hydration of thin films on solid surfaces can be obtained on the same specimen, as validated by monitoring the formation of supported lipid bilayers on a silica-coated QCM sensor surface. We emphasize that the optical (molecular) mass can be separated from the acoustic mass including hydrodynamically coupled solvent, which means, in turn, that the amount of solvent sensed by the QCM-D technique can be dynamically resolved during adsorption processes. In addition, the advantage/necessity to use four, compared to two, detector reflectometry is emphasized.

Model Membrane Platforms for Biomedicine: Case Study on Antiviral Drug Development

“…To investigate the mechanism by which AH peptide modulates the film properties of the intact vesicle layer, simultaneous QCM-D and reflectometry measurements to follow the AH peptide-mediated vesicle-to-bilayer transformation on gold have been reported [43]. While the acoustic wave-based QCM-D technique characterizes the structural properties of an adlayer film, the optical-based reflectometry technique provides a measure of the bound molecular mass that is related to the effective thickness and the effective refractive index of the adlayer [94]. When these two techniques are combined, several parameters can be simultaneously measured as a function of time, including: (1) adsorbed molecular mass (optical mass); (2) adsorbed molecular mass and solvent mass (acoustic mass); (3) effective film thickness; and (4) effective refractive index over the course of time [94].…”

“…While the acoustic wave-based QCM-D technique characterizes the structural properties of an adlayer film, the optical-based reflectometry technique provides a measure of the bound molecular mass that is related to the effective thickness and the effective refractive index of the adlayer [94]. When these two techniques are combined, several parameters can be simultaneously measured as a function of time, including: (1) adsorbed molecular mass (optical mass); (2) adsorbed molecular mass and solvent mass (acoustic mass); (3) effective film thickness; and (4) effective refractive index over the course of time [94]. As a result, the solvent mass can be calculated by separating the acoustic and optical masses.…”

Development of a combined surface plasmon resonance/surface acoustic wave device for the characterization of biomolecules

“…Optical sensors are sensitive to, e.g., the refractive index of the analyte which has been shown to be linearly related to the deposited mass [1]- [4]. Despite the existence of some reports [5]- [7], currently available optical technology does not generally allow for the detection of the conformation of an analyte and the way it is bound to a surface.…”

“…Manaka et al have combined a QCM with a simple and rugged optical fiber set-up to provide a compact, low-cost system for biosensing [3]. Wang et al have combined QCM-D (QCM with dissipation monitoring) with a modified reflectometry setup [4]; this system was used to study lipid, protein and peptide binding by evaluating acoustic frequency, dissipation, and the reflectometer response [20]. These investigations have demonstrated that quantitative extraction of physical parameters other than the amount of analyte is indeed possible with suitable combinations of acoustic and optical sensor elements.…”

Deposition of silica nanoparticles onto alumina measured by optical reflectometry and quartz crystal microbalance with dissipation techniques

“…A quartz crystal microbalance with dissipation detection (QCM-D) is very sensitive to mass changes and can be used in liquid solutions. Although both mass and dissipation are composite measures that include effects of solvent as well as nanoparticles, QCM-D has been used to monitor deposition of nanoparticles [12][13][14][15][16], also in combinations with combinatorial protocols [17].…”