Sensitive detection of ultra-weak adhesion states of vesicles by interferometric microscopy

TL;DR

This paper introduces a refined interferometric microscopy analysis to detect ultra-weak vesicle adhesion states, enabling precise measurement of membrane interactions that are otherwise indistinguishable from sedimentation effects.

Contribution

The study develops a new RICM analysis method that accounts for multiple interfaces and rays, improving detection of weak membrane-substrate interactions.

Findings

Successfully distinguished ultra-weak adhesion from sedimentation.

Quantitatively measured membrane-substrate distances around 30 nm.

Enhanced the sensitivity of RICM for weak biological interactions.

Abstract

We have used an original analysis of reflection interference contrast microscopy (RICM) to detect an ultra-weak specific interaction between a glycolipid vesicle and a lectin-coated substrate. The membrane height fluctuations in the contact zone are observed with a high illumination aperture; the membrane profile and the membrane-substrate distance are quantitatively determined using the new analysis, which accounts for multiple interfaces and multiple incidence rays. We showed that this refined version of RICM theory is necessary, specifically in the case of intermediate membranesubstrate distance (30 nm) and helped to discriminate between the ultra-weak interaction and pure gravitational sedimentation