This paper describes our progress in developing a unique family of functional bioresorbable poly(sophorolipid) biomaterials for use as scaffolds for tissue engineering. Lactonic sophorolipid (LSL(2Ac)) is a natural macrocyclic glycolipid produced in large quantity (>150 g/L) by fermentation of the yeast Candida bombicola. Our team used ring-opening metathesis polymerization (ROMP) to convert LSL(2Ac) into P(LSL(2Ac)) (Mn>100,000, Tg 61�C, Tm 123�C, semi-crystalline). To extend our understanding of LSL(2Ac) ROMP polymerizations, studies were conducted using Grubbs 2nd (G2) and 3rd (G3) generation catalysts to determine polymerization kinetics. Polymerizations were shown to be entropically driven toward an equilibrium which consists of about 70% polymer, 10% of oligomer and 20% monomer. The kp of G3 catalyzed ROMP continuously decreases as the polymerizations progress. Plots of ln{[M]0/[M]t} versus reaction time for G2 are linear, suggesting apparent first-order kinetic behavior. In G2 catalyzed LSL(2Ac) ROMP, a plot of Mn versus [monomer]/[initiator] ratio resembles the theoretical curve based on living polymerizations. To create a diversified set of macrocyclic glycolipid monomers and polymers, LSL(2Ac) was regioselectively modified at its two primary -OH positions, including deacetylation to prepare P(LSL(OH,Ac)) and esterification with various vinyl esters (e.g. vinyl butyrate to prepare LSL(Bu,Ac)). Clickable groups including methacrylate and azide were also selectively introduced into LSL monomers. There monomers were successfully converted into new SL (co)polymers with tailored properties and potential to conjugate bioactive groups. P(LSL(2Ac)), P(LSL(OH,Ac)), P(LSL(Bu,Ac)) films were selected to test their cytotoxicity and ability to support attachment and proliferation of human mesenchymal stem cells (h-MSC). After a 72 h culture time, h-MSC attachment and proliferation were statistically indistinguishable across the different poly(SL) structural analogs and relative to tissue culture polystyrene controls. In addition, after 72 h, no significant cytotoxic effects for these poly(sophorolipid) film surfaces were detected by lactate dehydrogenase (LDH) relative to tissue culture polystyrene controls. In addition, measurement of level of RUNX2 and alkaline phosphatase suggested the osteogenesis was upreguated on the polysophorolipid substrates.

Novel family of biobased polysophorolipids used as scaffolds for tissue engineering

248th National Meeting (2014)

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