Characterization of knitted polymeric scaffolds for potential use in ligament tissue engineering

Different scaffolds have been designed for ligament tissue engineering. Knitted scaffolds of poly-L-lactic acid (PLLA) yarns and co-polymeric yarns of PLLA and poly(glycolic acid) (PLGA) were characterized in the current study. The knitted scaffolds were immersed in medium for 20 weeks, before mass loss, molecular weight, pH value change in medium were tested; changes in mechanical properties were evaluated at different time points. Results showed that the knitted scaffolds had 44% porosity. There was no significant pH value change during degradation, while there was obvious mass loss at initial 4 week, as well as smooth molecular weight drop of PLLA. PLGA degraded more quickly, while PLLA kept its integrity for at least 20 weeks. Young's modulus increased while tensile strength and strain at break decreased with degradation time; however, all of them could maintain the basic requirements for ACL reconstruction. It showed that the knitted polymeric structures could serve as potential scaffolds for tissue-engineered ligaments.

Characterization of bulk properties of nanofibrous scaffolds from nanomechanical properties of single nanofibers

This article presents a method of characterizing the macromechanical properties of polymer nanofibrous scaffolds based on the nanomechanical properties obtained for a single nanofiber. Here, we use the example of a poly(L-lactic acid) (PLLA) nanofibrous scaffold that can be used for tissue engineering application. The elastic modulus of a single nanofiber obtained previously from a nanoscale three-point bend test performed using atomic force microscopy was used to model the elastic modulus and elastic collapse stress of the bulk scaffold. Various open-cell solid models are examined for the modeling of bulk scaffold behavior.

Tensile testing of a single ultrafine polymeric fiber

Due to the difficulty in handling micro and nanoscale fibers and measuring the small load required for deformation, mechanical properties of these fibers have not been widely characterized. In this study, tensile test of a single-strand polycaprolactone electrospun ultrafine fiber was performed using a nano tensile tester. The tested fiber exhibited the characteristic low strength and low modulus but high extensibility at room temperature. The mechanical properties were also found to be dependent on fiber diameter. Fibers with smaller diameter had higher strength but lower ductility due to the higher 'draw ratio' that was applied during the electrospinning process.