Soft Interferometric Nanostrain Sensor Reveals Solid-Liquid Interfacial Tension Oscillation Amplified by Competitive...

Area of Science:

• Biomaterials Science
• Surface Chemistry
• Nanotechnology

Background:

• Protein adsorption on biomaterials impacts hemocompatibility and infection risk.
• Current methods for studying protein adsorption are limited in real-time detection and may alter adsorption behavior due to labeling.

Purpose of the Study:

• To develop and utilize a novel interferometric nanostrain sensor for real-time, label-free investigation of protein mixture adsorption.
• To understand the dynamics of protein adsorption and its effect on interfacial tension.

Main Methods:

• An interferometric nanostrain sensor was employed, leveraging the elastocapillary effect to measure interfacial tension.
• The sensor detected nanometer deformation of a substrate caused by a sessile protein drop.
• Fetal bovine serum (FBS) was used to demonstrate the sensor's capability in quantifying adsorption.

Main Results:

• The solid-liquid interfacial tension (γSL) decreased with increasing FBS concentration, while solid-vapor tension (γSV) remained uncorrelated.
• Protein adsorption dynamics followed Langmuir characteristics on a coarse timescale.
• A novel high-frequency, low-amplitude oscillatory modulation of γSL was observed on a fine timescale, intrinsic to competitive adsorption.

Conclusions:

• The sensor provides a new method for ensemble-averaging and quantifying competitive protein adsorption in real-time.
• The findings reveal new mechanisms of protein-surface interactions and their link to macroscale surface energy.
• This technology can advance the engineering of biosurface functionalities for medical instruments and biomaterials.