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Abstract:
Despite the great potential of citrate polyesters in regenerative medicine, the data about their application in electrospinning is somewhat limited. In this work, poly(dimethylene citrate) (P-1,2-ECit), poly(tetramethylene citrate) (P-1,4-BCit), and poly(hexamethylene citrate) (P-1,6-HCit) were synthesized. Nonwovens from poly(diol citrates)/PLA mixtures were successfully electrospun and characterized using SEM, AFM, water contact angle measurement, DSC, TGA, and in vitro degradation tests. The addition of poly(diol citrates) increases the hydrophilicity and surface adhesion force of PLA nonwovens; however, the observed effects depend on the scale level (macro/micro) of the analysis. Diol chain length in poly(diol citrate) influences the compatibility and heterogeneity of its distribution within the carrier polymer. Additionally, it impacts the crystallinity of the PLA phase. Degradation tests show the problem of the nonwoven stability in the aqueous media and the high leachability of the short-chained poly(diol citrates). Addressing this issue is important regarding controlling the degradation kinetics. Despite the good processability in electrospinning and promising surface properties of the poly(diol citrates)/PLA mixtures, the instability of these materials in an aqueous environment is an important issue which can subsequently affect the performance of the eventual implant/cell scaffold. The solution may involve chain elongation of the hydrophilic oligomeric additive.

Keywords:
Electrospinning, Polyesters, Tissue Engineering, Functional Materials

Abstract:
Biomaterials containing citric acid as a building unit show potential for use as blood vessel and skin tissue substitutes. The success in commercializing implants containing a polymer matrix of poly(1,8-octanediol citrate) provides a rationale for exploring polycitrates based on other diols. Changing the aliphatic chain length of the diol allows functional design strategies to control the implant’s mechanical properties, degradation profile and surface energy. In the present work, poly(1,2-ethanediol citrate) was synthesized and used as an additive to polylactide in the electrospinning process. It was established that the content of polycitrate greatly influences the nonwovens’ properties: an equal mass ratio of polymers resulted in the best morphology. The obtained nonwovens were characterized by surface hydrophilicity, tensile strength, and thermal properties. L929 cell cultures were carried out on their surface. The materials were found to be non-cytotoxic and the degree of porosity was suitable for cell colonization. On the basis of the most important parameters for assessing the condition of cultured cells (cell density and viability, cell metabolic activity and lactate dehydrogenase activity), the potential of PLLA + PECit nonwovens for application in tissue engineering was established.