Assessing viscoelastic properties of chitosan scaffolds and validation with cyclical tests

Ratakonda, Swapnika; Sridhar, Upasana Manimegalai; Rhinehart, R. Russell; Madihally, Sundararajan V.

doi:10.1016/j.actbio.2011.12.013

Cited by 25 publications

(20 citation statements)

References 43 publications

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“…31 Therefore it is imperative to study the effects of cyclical loads on the hydrogel sections to determine durability, longevity, and deformity characteristics. 32 Thus, observed creep deformation in superficial zone hydrogels containing only chitosan and gelatin are consistent with other chitosan-gelatin scaffolds. The negative stress in the relaxation period of each cycle is attributed to the creep deformation, which eventually disappears in the radial and calcified hydrogels but remains in the superficial and anisotropic hydrogels.…”

Section: Cyclical Testingsupporting

confidence: 84%

Anisotropic temperature sensitive chitosan‐based injectable hydrogels mimicking cartilage matrix

Walker

Madihally

2014

J Biomed Mater Res

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In this study, chitosan-based hydrogels were formulated with material similarities to three of the four zones of articular cartilage. Gelatin, hyaluronic acid (HA), and β-tricalcium phosphate for the superficial, radial, and calcified zones, were blended in different amounts and tested for formation of uniform solution, gelability, and rheological characteristics. Confined compression in two configurations (series and parallel to anisotropy), and cyclical tests were performed at the physiological conditions. In vivo gelation and systemic effects were evaluated in male BALB/c mice subcutaneous model. At day 5, hydrogels were harvested along with the adjoining skin and analyzed by histology. Formulations that produced solutions after pH adjustments were selected for each zone. Anisotropic hydrogels were formed by mixing solutions from each zone, which showed uniform gradation. Addition of HA improved structural integrity relative to other formulations. When hydrogels were in series, combined hydrogel modulus was the average of all zones while that in parallel orientation was half of that series orientation. Cyclical tests demonstrated repeatable strength and durability. All formulations were injectable into the subcutaneous region. H/E stained tissues showed minimal invasion of inflammatory cells in radial and calcified zones. Structural integrity of the hydrogel is suggested to be the resultant of the presence of HA.

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Section: Cyclical Testingsupporting

confidence: 84%

Anisotropic temperature sensitive chitosan‐based injectable hydrogels mimicking cartilage matrix

Walker

Madihally

2014

J Biomed Mater Res

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“…Using an optical approach others have shown similar range of Poisson's ratio for synthetic scaffolds . However, Poisson's ratio for CG scaffolds was >0.5, typically considered to follow nonlinear elastic behavior . ECM rich lateral facet of human patellar cartilage is shown to have similar Poisson ratio when tested under identical method, although others have shown values to be <0.5.…”

Section: Resultsmentioning

confidence: 99%

“…28 However, Poisson's ratio for CG scaffolds was >0.5, typically considered to follow nonlinear elastic behavior. 26 ECM rich lateral facet of human patellar cartilage is shown to have similar Poisson ratio when tested under identical method, 29 although others have shown values to be <0.5. 27 To further confirm the behavior of CG scaffolds, three different sample preparations were utilized by varying freezing temperature and composition of the polymer.…”

Section: Scaffold Characterizationmentioning

confidence: 99%

Modeling of porous scaffold deformation induced by medium perfusion

Podichetty

Madihally

2013

J Biomed Mater Res

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In this study, we tested the possibility of calculating permeability of porous scaffolds utilized in soft tissue engineering using pore size and shape. We validated the results using experimental measured pressure drop and simulations with the inclusion of structural deformation. We prepared Polycaprolactone (PCL) and Chitosan-Gelatin (CG) scaffolds by salt leaching and freeze drying technique, respectively. Micrographs were assessed for pore characteristics and mechanical properties. Porosity for both scaffolds was nearly same but the permeability varied 10-fold. Elastic moduli were 600 and 9 kPa for PCL and CG scaffolds, respectively, while Poisson's ratio was 0.3 for PCL scaffolds and ∼1.0 for CG scaffolds. A flow-through bioreactor accommodating a 10 cm diameter and 0.2 cm thick scaffold was used to determine the pressure-drop at various flow rates. Additionally, computational fluid dynamic (CFD) simulations were performed by coupling fluid flow, described by Brinkman equation, with structural mechanics using a dynamic mesh. The experimentally obtained pressure drop matched the simulation results of PCL scaffolds. Simulations were extended to a broad range of permeabilities (10(-10) m(2) to 10(-14) m(2) ), elastic moduli (10-100,000 kPa) and Poisson's ratio (0.1-0.49). The results showed significant deviation in pressure drop due to scaffold deformation compared to rigid scaffold at permeabilities near healthy tissues. Also, considering the scaffold as a nonrigid structure altered the shear stress profile. In summary, scaffold permeability can be calculated using scaffold pore characteristics and deformation could be predicted using CFD simulation. These relationships could potentially be used in monitoring tissue regeneration noninvasively via pressure drop.

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“…Thus understanding the viscoelastic behavior of the scaffold material is necessary to know how it performs under various applications. Though there have been many studies to understand the viscoelastic properties of the soft tissues, those of the synthetic tissues are scarce . Porous polymeric biodegradable structures utilized in tissue regeneration also show viscoelastic behavior .…”

Section: Introductionmentioning

confidence: 99%

Influence of scaffold forming techniques on stress relaxation behavior of polycaprolactone scaffolds

Venkatesan

Makornkaewkeyoon

Khalf

et al. 2013

J of Applied Polymer Sci

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This study evaluated the effect of scaffold processing methods on viscoelastic properties of polycaprolactone (PCL), a frequently explored biomaterial in tissue engineering. 80 kDa and 45 kDa PCL scaffolds were synthesized using salt leaching and electrospinning techniques. Also, films were formed by air drying. Scanning electron microscopy analysis confirmed that salt leached scaffolds had open pore architecture and electrospun scaffolds had randomly distributed uniform fibers. Using the tensile test results in phosphate buffered saline (pH57.4) and 37 C, ramp-hold tests were performed for five stages by setting the strain rate to be 1%s 21 for 2 s followed by 58 s of hold. Also, tests were performed at various strain rates and total strain. Salt leached scaffolds of same MW showed less relaxation in each stage relative to electrospun scaffolds. 45 kDa salt leached scaffolds relaxed more than 80 kDa scaffolds. Stress accumulated in each stage was more in films than in scaffolds. However, relaxation function appeared similar between films and electrospun fibers. Strain rate and amount of applied strain had significant effect on relaxation characteristics; 0.6%s 21 strain rate had higher accumulated stress than 1%s 21 and 3%s 21 . Increased amount of loading had significant effect in the first stage with repetitive relaxation characteristics in subsequent stages. SEM analysis of tested samples showed no change in the microstructure with the exception of a few locations where pores oriented in the direction of the pull. In summary, viscoelastic characteristics vary based on the type of scaffold processing used, despite use of the same polymer. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4237-4244, 2013

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Assessing viscoelastic properties of chitosan scaffolds and validation with cyclical tests

Cited by 25 publications

References 43 publications

Anisotropic temperature sensitive chitosan‐based injectable hydrogels mimicking cartilage matrix

Anisotropic temperature sensitive chitosan‐based injectable hydrogels mimicking cartilage matrix

Modeling of porous scaffold deformation induced by medium perfusion

Influence of scaffold forming techniques on stress relaxation behavior of polycaprolactone scaffolds

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