Hydrated human corneal stroma revealed by quantitative dynamic atomic force microscopy at nanoscale

Area of Science:

• Biophysics
• Materials Science
• Ophthalmology

Background:

• Water significantly influences the structure and mechanical properties of human tissues.
• The functionality of the human cornea is closely related to its hydrated collagen fibers.

Purpose of the Study:

• To investigate morphological and mechanical property variations of corneal stroma under different hydration levels.
• To understand the impact of hydration on collagen fiber structure and stiffness.
• To explore age-dependency in corneal stiffness.

Main Methods:

• Quantitative dynamic atomic force microscopy (AFM) was employed.
• Analysis focused on morphological and nanomechanical properties of corneal stroma.
• Experiments were conducted across a range of hydration levels.

Main Results:

• At 40% humidity, corneal collagen fibers exhibited periodic structures with giga-Pascal (GPa) stiffness.
• Increased hydration led to nanoparticle structures along fibers with mega-Pascal (MPa) stiffness.
• Extended hydration time restored fiber structure but with increased diameter; age-dependent stiffness was observed.

Conclusions:

• Hydration level critically dictates the nanostructure and mechanical properties of corneal stroma.
• The observed changes in collagen fiber morphology and stiffness under varying hydration are significant.
• Nanomechanical mapping of tissue structure holds potential for future diagnostic and pathological analysis of the cornea.