Nano-Scale Stiffness and Collagen Fibril Deterioration: Probing the Cornea Following Enzymatic Degradation Using Peakforce-QNM AFM.

Sensors (Basel)

Department of Mechanical, Materials and Aerospace Engineering, School of Engineering, University of Liverpool, Liverpool L69 3GH, UK.

Published: February 2021

AI Article Synopsis

  • The cornea is affected by enzymes like amylase and collagenase, which can alter its structure and potentially lead to vision problems, such as keratoconus.
  • This study examines porcine corneas' structure and mechanical properties after exposure to varying concentrations of these enzymes using atomic force microscopy (AFM).
  • Results show that amylase reduces collagen fibril diameters and elastic modulus, while collagenase has a more significant impact, suggesting these findings could help understand keratoconus and aid in creating an animal model to study its progression.

Article Abstract

Under physiological conditions, the cornea is exposed to various enzymes, some of them have digestive actions, such as amylase and collagenase that may change the ultrastructure (collagen morphology) and sequentially change the mechanical response of the cornea and distort vision, such as in keratoconus. This study investigates the ultrastructure and nanomechanical properties of porcine cornea following incubation with α-amylase and collagenase. Atomic force microscopy (AFM) was used to capture nanoscale topographical details of stromal collagen fibrils (diameter and D-periodicity) and calculate their elastic modulus. Samples were incubated with varying concentrations of α-amylase and collagenase (crude and purified). Dimethylmethylene blue (DMMB) assay was utilised to detect depleted glycosaminoglycans (GAGs) following incubation with amylase. Collagen fibril diameters were decreased following incubation with amylase, but not D-periodicity. Elastic modulus was gradually decreased with enzyme concentration in amylase-treated samples. Elastic modulus, diameter, and D-periodicity were greatly reduced in collagenase-treated samples. The effect of crude collagenase on corneal samples was more pronounced than purified collagenase. Amylase was found to deplete GAGs from the samples. This enzymatic treatment may help in answering some questions related to keratoconus, and possibly be used to build an empirical animal model of keratoconic corneas with different progression levels.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7956234PMC
http://dx.doi.org/10.3390/s21051629DOI Listing

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