Eliminating Size-Associated Diffusion Constraints for Rapid On-Surface Bioassays with Nanoparticle Probes

Area of Science:

• Biotechnology
• Surface Science
• Analytical Chemistry

Background:

• Nanoparticle probes are crucial for advanced on-surface bioassays but face size-related limitations affecting assay speed and sensitivity.
• Conventional assay methods struggle to overcome the nanoprobe depletion layer that hinders diffusion-limited kinetics.

Purpose of the Study:

• To investigate a novel cyclic solution exchange method to overcome size-dependent diffusion constraints in nanoparticle-based on-surface bioassays.
• To demonstrate the effectiveness of this approach in accelerating assay kinetics and improving sensitivity.

Main Methods:

• Utilized cyclic solution draining and replenishing to disrupt the nanoprobe depletion layer.
• Applied the method to common surface bioassays, including enzyme-linked immunosorbent assays (ELISA) and immunofluorescence.
• Evaluated assay kinetics, sensitivity, and efficiency with varying nanoprobe concentrations and sizes.

Main Results:

• Cyclic solution exchange achieved reaction-limited assay kinetics, independent of probe size.
• Significantly reduced assay times from hours to minutes without compromising probe concentration.
• Enabled comparable target labeling with up to eight times lower nanoprobe concentration.

Conclusions:

• The cyclic solution exchange method effectively eliminates size-dependent diffusion constraints in on-surface bioassays.
• This approach provides a rapid and efficient route for on-surface bioassays using bulky nanoparticle probes.
• The findings are expected to drive the development of novel assay formats and rapid bioassays.