Follow surface events step-by-step
Thin film interactions
QCM-D is a highly sensitive technique for studying the formation of thin films and their interactions. Measurements can be carried out label-free on any surface that can be applied as a thin film.
Applications include protein conformational changes, lipids, polymers and whole cells. It is possible to determine the water content of molecular layers and calculate film viscosity, elasticity, mass, thickness, density, affinity and specificity. Interactions can be studied on many substrates such as gold, metals, polymers and functionalised coatings.
Click here to contact usThe principle is that of a Quartz Crystal Microbalance, with the additional measurement of Dissipation. The sensor is a quartz crystal disc, which oscillates at a constant frequency. As the mass on the crystal changes, so does the resonance frequency. In this way mass changes can be measured with nanogram sensitivity. Less than 1% of a protein monolayer can be detected. Dissipation provides information about the structure and viscoelasticity of the film. Analyses are made in real-time and the kinetics of both mass and structural changes are obtained simultaneously.
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| Quartz crystal disc with gold surface |
Mounting the quartz disc in the temperature controlled chamber is quick and easy |
Frequency-mass. The disc oscillation frequency is related to the total mass ie film plus water. If the film is thin and rigid the frequency can be used in the Sauerbrey relation to calculate the total mass on the disc surface. If the density is known then the film thickness can be calculated.
Dissipation-viscoelasticity. Viscoelastic films dampen the disc oscillation more than rigid films and the Sauerbrey relation is no longer valid. A compact globular protein gives low dissipation (rigid), while an elongated protein with coupled water results in higher dissipation (viscoelastic). It is the dissipation that gives the structural information. By driving the disc at multiple harmonic frequencies and using Q-tools software models, it is possible to calculate the values of film thickness, viscosity, elasticity and density.
Click here to contact usQCM-D with microscopy
QCM-D can be combined with light microscopy using the window module. The visual access to the sensor surface enables correlation of real-time microscopy to changes in mass and viscoelastic properties. The compact design enables studies of light-induced reactions and cell adhesion.
QCM-D with electrochemistry
Electrochemistry is ideally suited to be paired with QCM-D since both are surface techniques. QCM-D can provide real-time information on mass and structure of thin films while electrochemistry can be the stimulus of an interaction or provide information about interfacial charge transfer. Applications include electrostatic interactions of biomolecules with surfaces (redox proteins, cells, DNA,) and membrane potential measurements.
QCM-D with ellipsometry.This module enables simultaneous measurements with ellipsometry.
The QCM-D instrumentation
The Q-sense E4 comprises an electronic module with separate measurement chamber and controlled by Q-soft software installed on the system PC. The measurement chamber houses up to four removable flow modules, each holding a sensor. The flow modules can be used in any serial or parallel configuration with simultaneous measurement of all four sensors. The Q-sense E1 has the same analytical performance as the E4 except that it incorporates a single flow module with sensor instead of 4 parallel flow modules.
Click here to contact usFeatures of the E1 and E4
Measure the mass of molecular layers forming on the surface with nanogram sensitivity. For example, 1% or less of a protein monolayer can be detected.
Structural changes measured simultaneously so as to distinguish between two similar binding events or observe a phase transition in bound layers.
Real time measurements allowing recording and evaluation of kinetics
Flow measurements in a temperature-controlled environment
Multi-frequency measurements up to 6 overtones can be measured in addition to the fundamental frequency. Overtones provide more reliable measurements and enable modelling of the film characteristics.
Flexible choice of surface including metals, polymers and chemically/biologically modified surfaces. Any surface that can be applied as a thin film can be used. The most commonly used sensor surface is pure gold as it is chemically inert and easy to modify to thiolated gold which creates a hydrophobic surface.
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