Biophysical study of mechanical properties of keratoconus cornea
Maryam Akbari1 *, Hamid Mobasheri2 , Alireza Nourizadeh3 , Seyed-Hashem Daryabari4
- Laboratory of Membrane Biophysics and Macromolecules, Institute of Biochemistry and Biophysics, University of Tehran, Iran
- Institute of Biomaterials of University of Tehran and Tehran University of Medical Sciences (IBUTUMS), Tehran, Iran
- Basir Eye Health Research Center, Tehran, Iran
- Chemical Injuries Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
Abstract: Cornea is the primary refracting component of the human visual system. Transparency and biophysical properties of the cornea depends on its geometry (topography) thickness and stiffness. Keratoconus (KCN) is a progressive corneal disease characterized by thinning and weakening of the cornea. Ectasia in the apex of keratoconus corneas alters the organization of collagen (Col). Application of static magnetic field (MF) has attracted growing attention in the clinical magneto-therapy due to its non-invasive, direct and targeted effect nature.
Methods: In this research, the effects of SMF 300mT on the biophysical and biomechanical properties of corneal tissue and collagen extracted from rat tail were investigated. Rheological measurements of the cornea (KCN) were performed. The purity of Col. I was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis method. The Physic-chemical characterization of the collagen was studied using Circular Dichroism (CD) spectroscopy and Fourier Transforms Infrared Spectroscopy (FTIR). The follow up results of the study is justified on disposed and/or about to be outed human KCN cornea by OCT and Sirius instruments.
Results: The storage modulus of the cornea (KCN (in the presence of the SMF significantly increased after 5 minutes (Frequency 0.05% strain). The rheological experiments revealed changes in the viscoelastic behavior of collagen due to exposure to SMF 300mT making it less elastic. The secondary structure of collagen was effected by the applied SMF resulting in transformation of the random coil structure to the antiparallel β sheet structure. However, there was no significant changes monitored in the structures of helix and beta turn.
Conclusion: The secondary structure of collagen type I molecules and biomechanical properties of cornea can be manipulated by their exposure to a tailored SMF. Furthermore, due to the widespread presence of collagens in different part of tissue, SMF based treatment might be considered for treatment of other diseases.
