Poly(Caprolactone Fumarate) and Oligo[Poly(Ethylene Glycol) Fumarate]: Two Decades of Exploration in Biomedical Applications

The past few decades have seen a significant interest in the fumarate-based polymers for biomedical applications. Poly(caprolactone fumarate) (PCLF) and oligo[poly(ethylene glycol) fumarate] (OPF) are derivatives of polycaprolactone and polyethylene glycol respectively, which are rendered cross-linkable, biodegradable, and possess tunable mechanical properties by the introduction of unsaturated fumarate groups. PCLF is a hydrophobic polymer, mostly applied as pre-formed or 3-D printed scaffolds while OPF is an aqueous-solvent based polymer mostly explored as a hydrogel system in tissue regeneration and drug delivery applications. This review summarizes the synthesis methods of these two polymers and the improvements on these methods over the years. The influence of precursor monomers on the physical properties of the synthesized polymer is comprehensively described, along with the cross-linking strategies. The major focus of this review is to highlight the applications of PCLF and OPF over the years in nerve, cartilage, and bone tissue engineering, as well as drug delivery applications. The nano- and micro- composites developed using these polymers to better accommodate the required application especially in cartilage and bone tissue regeneration are explained in detail. Finally, we provide our perspective on future directions for these polymers in regenerative medicine.