(549b) In Vitro Characterization of Polycaprolactone Scaffolds: Effect of Blending Different Molecular Weights

Polycaprolactone (PCL) is biocompatible polyester with low melting point (60(C). It is explored in forming various medical devices, templates in tissue regeneration, and drug delivery systems. Ability to tailor its mechanical and non-enzymatic degradation (by hydrolysis) properties by altering MW are very attractive properties; PCL membranes formed after dissolution in chloroform show elongation up to 1000% before break. However, the poor wettability of the prepared matrices prevents uniform distribution of proteins and cell adhesion, thus compromising their application as tissue engineering templates.

In this study, a novel process of dissolving Polycaprolactone (PCL) matrices in glacial acetic acid was explored which spontaneously formed matrices upon contact with water. From each MW PCL, 10% (wt/v) solutions were prepared in glacial acetic acid. Blend solutions containing different MW PCL were prepared by mixing equal volumes of individual solutions using factorial design of experiments 1:0:0, 1:1:0, 1:1:1, 1:0:1 (all abbreviations are in the order of 80:46:10 kDa Mn), and PCL of 80 kDa Mn solution was prepared in chloroform to compare the effect of solvent. Scanning electron microscopy (SEM) analysis revealed increased roughness of these matrices relative to matrices formed after dissolving in chloroform. Atomic force microscopy (AFM) study showed that roughness factor was decreased by blending with lower MW of PCL, and immersion in NaOH decreased roughness. Mechanical test results showed a significant decrease in the tensile stress of blended matrices (tensile stress is in the range of 2 to 3 MPa for mixing ratio of 1:1:1) relative to 80 kDa matrix (tensile stress is in the range of 13 to 14 MPa for 80 kDa PCL). Stress relaxation was tested at the strain rate of 1% s-1 for 50 s and relaxation time period of 100 s to understand the implication of self assembly. These results showed that both acetic acid and chloroform casted matrixes had similar behavior in ramp and hold cycles. In the first ramp and hold cycle, both matrixes had a high stress level for the same amount of strain. However, in the successive ramp-hold conditions, there were no significant differences. In vitro cell cultures were conducted using Human Foreskin fibroblasts (HFF-1) for four days. Cytoskeletal actin staining showed cell adhesion and spreading on all matrices. Further, cells attached and grew on matrices, with no significant difference in the specific growth rate constant between different MWs and their blends. In summary, PCL matrices can be generated using the novel technique with easy blending of different MW PCL.