Quartz Crystal Microbalance Frequency Response to Discrete Adsorbates in Liquids

Area of Science:

• Surface science
• Nanotechnology
• Biophysics

Background:

• Quartz Crystal Microbalance with Dissipation monitoring (QCM-D) is crucial for studying adsorption kinetics of nanomaterials in liquid.
• Quantitative analysis of QCM-D data in liquids is challenging due to complex hydrodynamic and adhesion forces.
• Understanding these forces is vital for accurate interpretation of QCM-D experiments.

Purpose of the Study:

• To theoretically dissect the role of hydrodynamics in QCM-D measurements of adsorbed nanometric objects.
• To provide a framework for accurate interpretation of QCM-D impedance measurements in liquid environments.
• To quantify the contribution of hydrodynamic forces to the measured response.

Main Methods:

• Theoretical analysis of excess shear force exerted on the QCM-D resonator under low surface coverage.
• Modeling fluid-mediated forces and contact forces transmitted via adsorbed particles.
• Comparison of theoretical results with experimental data and numerical simulations.

Main Results:

• Hydrodynamic forces significantly influence QCM-D measurements in liquids, particularly for particles comparable in size to proteins.
• The apparent mass derived from QCM-D can be approximately 10 times the Sauerbrey (inertial) mass due to hydrodynamic effects.
• Theoretical predictions show excellent agreement with experimental and simulation data across various particle sizes and frequencies.

Conclusions:

• Hydrodynamic interactions are a dominant factor in QCM-D measurements of nanometric object adsorption in liquids.
• The developed theoretical model allows for more accurate interpretation of QCM-D data by accounting for hydrodynamic forces.
• This work provides a foundation for precise quantitative analysis in QCM-D studies involving nanoparticle adsorption.