A novel nanolayer biosensor principle

Area of Science:

• Biosensor technology
• Surface science
• Biophysics

Background:

• Evanescent wave and SPR biosensors are crucial for measuring macromolecular binding kinetics.
• Current methods face limitations with large biomolecules due to mass transport limitations from Nernst diffusion layers.
• These limitations hinder accurate determination of binding constants for proteins and DNA.

Purpose of the Study:

• To introduce a novel method for eliminating mass transport limitations on biosensor surfaces.
• To enable rigorous measurement of binding kinetics for large macromolecules.
• To enhance the speed and accuracy of biosensor analyses.

Main Methods:

• Utilized an immiscible fluid vesicle (air bubble) to create nanoscopic fluid films (approx. 200 nm) on sensor surfaces.
• Employed interfacial TIRF rheometer systems and evanescent wave technology to generate and measure nanofilm thickness.
• Investigated the fluid dynamics and properties of the generated nanofluidic films.

Main Results:

• The nanofilm technique significantly increased the mass transport coefficient for fibrinogen (340 kDa) from 2 x 10(-6) m/s to 1 x 10(-4) m/s.
• Mass transport limitations were eliminated, making binding rates reaction-rate limited and allowing kinetic constants to be extracted from 20-30s exponential kinetic functions.
• Observed unique properties of the nanofluidic film, including persistence and absence of solute depletion, attributed to a "vortex sheet" mechanism.

Conclusions:

• The developed nanofilm technique offers a fundamentally novel approach to constructing advanced macromolecular biosensors.
• This method overcomes previous limitations, enabling precise kinetic analysis of large biomolecules.
• The findings pave the way for more sensitive and efficient biosensing applications.