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Shahab S, Kasra M, Dolatshahi-Pirouz A. Design and construction of a novel measurement device for mechanical characterization of hydrogels: A case study. PLoS One 2021; 16:e0247727. [PMID: 33630967 PMCID: PMC7906418 DOI: 10.1371/journal.pone.0247727] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 02/12/2021] [Indexed: 11/19/2022] Open
Abstract
Natural biopolymer-based hydrogels especially agarose and collagen gels, considering their biocompatibility with cells and their capacity to mimic biological tissues, have widely been used for in-vitro experiments and tissue engineering applications in recent years; nevertheless their mechanical properties are not always optimal for these purposes. Regarding the importance of the mechanical properties of hydrogels, many mechanical characterization studies have been carried out for such biopolymers. In this work, we have focused on understanding the mechanical role of agarose and collagen concentration on the hydrogel strength and elastic behavior. In this direction, Amirkabir Magnetic Bead Rheometry (AMBR) characterization device equipped with an optimized electromagnet, was designed and constructed for the measurement of hydrogel mechanical properties. The operation of AMBR set-up is based on applying a magnetic field to actuate magnetic beads in contact with the gel surface in order to actuate the gel itself. In simple terms the magnetic beads leads give rise to mechanical shear stress on the gel surface when under magnetic influence and together with the associated bead-gel displacement it is possible to calculate the hydrogel shear modulus. Agarose and Collagen gels with respectively 0.2-0.6 wt % and 0.2-0.5 wt % percent concentrations were prepared for mechanical characterization in terms of their shear modulus. The shear modulus values for the different percent concentrations of the agarose gel were obtained in the range 250-650 Pa, indicating the shear modulus increases by increasing in the agar gel concentration. In addition to this, the values of shear modulus for the collagen gel increase as function of concentration in the range 240-520 Pa in accordance with an approximately linear relationship between collagen concentration and gel strength.
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Affiliation(s)
- Shayan Shahab
- Tissue Engineering Laboratory, Biomedical Engineering Faculty, Amirkabir University of Technology-Tehran Polytechnic, Tehran, Iran
| | - Mehran Kasra
- Tissue Engineering Laboratory, Biomedical Engineering Faculty, Amirkabir University of Technology-Tehran Polytechnic, Tehran, Iran
| | - Alireza Dolatshahi-Pirouz
- Department of Health Technology, Institute of Biotherapeutic Engineering and Drug Targeting, Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, Kgs Lyngby, Denmark
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Hersh DS, Nguyen BA, Dancy JG, Adapa AR, Winkles JA, Woodworth GF, Kim AJ, Frenkel V. Pulsed ultrasound expands the extracellular and perivascular spaces of the brain. Brain Res 2016; 1646:543-550. [PMID: 27369449 DOI: 10.1016/j.brainres.2016.06.040] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 06/26/2016] [Accepted: 06/27/2016] [Indexed: 10/21/2022]
Abstract
Diffusion within the extracellular and perivascular spaces of the brain plays an important role in biological processes, therapeutic delivery, and clearance mechanisms within the central nervous system. Recently, ultrasound has been used to enhance the dispersion of locally administered molecules and particles within the brain, but ultrasound-mediated effects on the brain parenchyma remain poorly understood. We combined an electron microscopy-based ultrastructural analysis with high-resolution tracking of non-adhesive nanoparticles in order to probe changes in the extracellular and perivascular spaces of the brain following a non-destructive pulsed ultrasound regimen known to alter diffusivity in other tissues. Freshly obtained rat brain neocortical slices underwent sham treatment or pulsed, low intensity ultrasound for 5min at 1MHz. Transmission electron microscopy revealed intact cells and blood vessels and evidence of enlarged spaces, particularly adjacent to blood vessels, in ultrasound-treated brain slices. Additionally, ultrasound significantly increased the diffusion rate of 100nm, 200nm, and 500nm nanoparticles that were injected into the brain slices, while 2000nm particles were unaffected. In ultrasound-treated slices, 91.6% of the 100nm particles, 20.7% of the 200nm particles, 13.8% of the 500nm particles, and 0% of the 2000nm particles exhibited diffusive motion. Thus, pulsed ultrasound can have meaningful structural effects on the brain extracellular and perivascular spaces without evidence of tissue disruption.
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Affiliation(s)
- David S Hersh
- Department of Neurosurgery, University of Maryland School of Medicine, 22 S Greene St Suite 12D, Baltimore, MD 21201, USA; Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, 22 S Greene St, Baltimore, MD 21201, USA
| | - Ben A Nguyen
- Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, 419 W Redwood St Suite 110, Baltimore, MD 21201, USA
| | - Jimena G Dancy
- Department of Neurosurgery, University of Maryland School of Medicine, 22 S Greene St Suite 12D, Baltimore, MD 21201, USA; Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, 22 S Greene St, Baltimore, MD 21201, USA
| | - Arjun R Adapa
- Department of Neurosurgery, University of Maryland School of Medicine, 22 S Greene St Suite 12D, Baltimore, MD 21201, USA; Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, 22 S Greene St, Baltimore, MD 21201, USA
| | - Jeffrey A Winkles
- Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, 22 S Greene St, Baltimore, MD 21201, USA; Department of Surgery, University of Maryland School of Medicine, 22 S Greene St, Baltimore, MD 21201, USA; Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, UMB BioPark, One Room 210, 800 West Baltimore Street Baltimore, MD 21201, USA
| | - Graeme F Woodworth
- Department of Neurosurgery, University of Maryland School of Medicine, 22 S Greene St Suite 12D, Baltimore, MD 21201, USA; Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, 22 S Greene St, Baltimore, MD 21201, USA
| | - Anthony J Kim
- Department of Neurosurgery, University of Maryland School of Medicine, 22 S Greene St Suite 12D, Baltimore, MD 21201, USA; Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, 22 S Greene St, Baltimore, MD 21201, USA; Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, 20 Penn Street, HSFII Room 520, Baltimore, MD 21201, USA; Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, 111 S. Penn St. Suite 104, Baltimore, MD 21201, USA.
| | - Victor Frenkel
- Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, 22 S Greene St, Baltimore, MD 21201, USA; Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, 419 W Redwood St Suite 110, Baltimore, MD 21201, USA.
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