Viscoelastic damage evaluation of the axon
In this manuscript, we have studied the microstructure of the axonal cytoskeleton and adopted a bottom-up approach to evaluate the mechanical responses of axons. The cytoskeleton of the axon includes the microtubules (MT), Tau proteins (Tau), neurofilaments (NF), and microfilaments (MF). Although mo...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Frontiers Media S.A.
2022-10-01
|
| Series: | Frontiers in Bioengineering and Biotechnology |
| Subjects: | |
| Online Access: | https://www.frontiersin.org/articles/10.3389/fbioe.2022.904818/full |
| _version_ | 1797997243030044672 |
|---|---|
| author | Fuad Hasan KAH Al Mahmud Md. Ishak Khan Ashfaq Adnan |
| author_facet | Fuad Hasan KAH Al Mahmud Md. Ishak Khan Ashfaq Adnan |
| author_sort | Fuad Hasan |
| collection | DOAJ |
| description | In this manuscript, we have studied the microstructure of the axonal cytoskeleton and adopted a bottom-up approach to evaluate the mechanical responses of axons. The cytoskeleton of the axon includes the microtubules (MT), Tau proteins (Tau), neurofilaments (NF), and microfilaments (MF). Although most of the rigidity of the axons is due to the MT, the viscoelastic response of axons comes from the Tau. Early studies have shown that NF and MF do not provide significant elasticity to the overall response of axons. Therefore, the most critical aspect of the mechanical response of axons is the microstructural topology of how MT and Tau are connected and construct the cross-linked network. Using a scanning electron microscope (SEM), the cross-sectional view of the axons revealed that the MTs are organized in a hexagonal array and cross-linked by Tau. Therefore, we have developed a hexagonal Representative Volume Element (RVE) of the axonal microstructure with MT and Tau as fibers. The matrix of the RVE is modeled by considering a combined effect of NF and MF. A parametric study is done by varying fiber geometric and mechanical properties. The Young’s modulus and spacing of MT are varied between 1.5 and 1.9 GPa and 20–38 nm, respectively. Tau is modeled as a 3-parameter General Maxwell viscoelastic material. The failure strains for MT and Tau are taken to be 50 and 40%, respectively. A total of 4 RVEs are prepared for finite element analysis, and six loading cases are inspected to quantify the three-dimensional (3D) viscoelastic relaxation response. The volume-averaged stress and strain are then used to fit the relaxation Prony series. Next, we imposed varying strain rates (between 10/sec to 50/sec) on the RVE and analyzed the axonal failure process. We have observed that the 40% failure strain of Tau is achieved in all strain rates before the MT reaches its failure strain of 50%. The corresponding axonal failure strain and stress vary between 6 and 11% and 5–19.8 MPa, respectively. This study can be used to model macroscale axonal aggregate typical of the white matter region of the brain tissue. |
| first_indexed | 2024-04-11T10:29:54Z |
| format | Article |
| id | doaj.art-100a1ba724cf4b6da5a0178c494b846f |
| institution | Directory Open Access Journal |
| issn | 2296-4185 |
| language | English |
| last_indexed | 2024-04-11T10:29:54Z |
| publishDate | 2022-10-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Bioengineering and Biotechnology |
| spelling | doaj.art-100a1ba724cf4b6da5a0178c494b846f2022-12-22T04:29:28ZengFrontiers Media S.A.Frontiers in Bioengineering and Biotechnology2296-41852022-10-011010.3389/fbioe.2022.904818904818Viscoelastic damage evaluation of the axonFuad Hasan0KAH Al Mahmud1Md. Ishak Khan2Ashfaq Adnan3Department of Mechanical and Aerospace Engineering, The University of Texas at Arlington, Arlington, TX, United StatesDepartment of Mechanical and Aerospace Engineering, The University of Texas at Arlington, Arlington, TX, United StatesPerelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United StatesDepartment of Mechanical and Aerospace Engineering, The University of Texas at Arlington, Arlington, TX, United StatesIn this manuscript, we have studied the microstructure of the axonal cytoskeleton and adopted a bottom-up approach to evaluate the mechanical responses of axons. The cytoskeleton of the axon includes the microtubules (MT), Tau proteins (Tau), neurofilaments (NF), and microfilaments (MF). Although most of the rigidity of the axons is due to the MT, the viscoelastic response of axons comes from the Tau. Early studies have shown that NF and MF do not provide significant elasticity to the overall response of axons. Therefore, the most critical aspect of the mechanical response of axons is the microstructural topology of how MT and Tau are connected and construct the cross-linked network. Using a scanning electron microscope (SEM), the cross-sectional view of the axons revealed that the MTs are organized in a hexagonal array and cross-linked by Tau. Therefore, we have developed a hexagonal Representative Volume Element (RVE) of the axonal microstructure with MT and Tau as fibers. The matrix of the RVE is modeled by considering a combined effect of NF and MF. A parametric study is done by varying fiber geometric and mechanical properties. The Young’s modulus and spacing of MT are varied between 1.5 and 1.9 GPa and 20–38 nm, respectively. Tau is modeled as a 3-parameter General Maxwell viscoelastic material. The failure strains for MT and Tau are taken to be 50 and 40%, respectively. A total of 4 RVEs are prepared for finite element analysis, and six loading cases are inspected to quantify the three-dimensional (3D) viscoelastic relaxation response. The volume-averaged stress and strain are then used to fit the relaxation Prony series. Next, we imposed varying strain rates (between 10/sec to 50/sec) on the RVE and analyzed the axonal failure process. We have observed that the 40% failure strain of Tau is achieved in all strain rates before the MT reaches its failure strain of 50%. The corresponding axonal failure strain and stress vary between 6 and 11% and 5–19.8 MPa, respectively. This study can be used to model macroscale axonal aggregate typical of the white matter region of the brain tissue.https://www.frontiersin.org/articles/10.3389/fbioe.2022.904818/fullmechanical behavior of axonneuroncytoskeletontraumatic brain injuryfinite element analysisrepresentative volume element (RVE) |
| spellingShingle | Fuad Hasan KAH Al Mahmud Md. Ishak Khan Ashfaq Adnan Viscoelastic damage evaluation of the axon Frontiers in Bioengineering and Biotechnology mechanical behavior of axon neuron cytoskeleton traumatic brain injury finite element analysis representative volume element (RVE) |
| title | Viscoelastic damage evaluation of the axon |
| title_full | Viscoelastic damage evaluation of the axon |
| title_fullStr | Viscoelastic damage evaluation of the axon |
| title_full_unstemmed | Viscoelastic damage evaluation of the axon |
| title_short | Viscoelastic damage evaluation of the axon |
| title_sort | viscoelastic damage evaluation of the axon |
| topic | mechanical behavior of axon neuron cytoskeleton traumatic brain injury finite element analysis representative volume element (RVE) |
| url | https://www.frontiersin.org/articles/10.3389/fbioe.2022.904818/full |
| work_keys_str_mv | AT fuadhasan viscoelasticdamageevaluationoftheaxon AT kahalmahmud viscoelasticdamageevaluationoftheaxon AT mdishakkhan viscoelasticdamageevaluationoftheaxon AT ashfaqadnan viscoelasticdamageevaluationoftheaxon |