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

Abstract

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

Assessment of cell proliferation in salt‐leaching using powder (SLUP) scaffolds with penetrated macro‐pores

“…Last, the mixture of PCL/NaCl was cut into cubes with dimensions of 10 × 10 × 10 mm 3 , as depicted in Figure (d), and the cut scaffolds were soaked in a beaker filled with DI water. Leaching out NaCl was performed for 24 h using a sonicator (the water was changed every 6 h) , , and then, the scaffolds were dried for 24 h using a desiccator. Consequently, the fabricated scaffolds were depicted in Figure .…”

In vitro characterization of acelluar porcine adipose tissue matrix for use as a tissue regenerative scaffold

“…aPAM demonstrated strain‐hardening behavior (i.e., lower maximum stress developed in the first cycle relative to the fourth stage) in successive stages similar to many soft tissues; the stress developed in the first stage was significantly less than that in the fifth stage. The relaxation behavior of aPAM was different from synthetic scaffolds made of 50:50 poly‐lactide‐co‐glycolide (PLGA) films, polycaprolactone (PCL) scaffolds, or chitosan and chitosan/gelatin porous scaffolds . PLGA films demonstrate strain softening characteristic.…”

“…However, percentage relaxation in synthetic scaffolds depends on the method of preparation, and molecular weight. Chitosan scaffolds showed 90% relaxation property but PCL scaffolds show 25% relaxation . To further understand the viscoelastic properties, one has to determine the relaxation times and predict other characteristics.…”

“…In addition, while a variety of specific like‐to‐like scaffolds (that is, cadaverous human tendon to replace patient tendon) have seen clinical usage, there is a need for “off the shelf” homogeneous scaffolds to replace a variety of tissues. To address the constraint of obtaining reliable, reproducible natural matrixes in large‐scale preparations, forming synthetic matrices from natural and synthetic polymers and using other abundant natural tissue sources have been explored.…”

Alternative Form of Standard Linear Solid Model for Characterizing Stress Relaxation and Creep: Including a Novel Parameter for Quantifying the Ratio of Fluids to Solids of a Viscoelastic Solid

“…The standard linear solid model is much simpler compared to other more general models like the generalized Maxwell model and fractional-order viscoelastic model (Xiao et al, 2016). Nevertheless, the standard linear solid model is still useful for analyzing viscoelastic behaviors of many biomaterials like polycaprolactone scaffolds (Sethuraman et al, 2013) and hydrogels (Shazly et al, 2008;Feng et al, 2010;Tirella et al, 2014;Cacopardo et al, 2019). In addition, the results by using the standard linear solid model is easier to interpret since the model produces only three parameters (Braunsmann et al, 2014).…”