Functional polyesters for drug delivery and 3D printing

Funtional ɛCL monomers have been successfully synthesised utilising a primary amine (protected as a CBZ or BOC carbamate) and also a protected ketone (using an acetal protecting group). Amine derivatives were synthesised from the commercially available trans-4-aminocyclohexanol. The acetal protected ketone was synthesised from the commercially available 1,4-cyclohexanedione monoethylene acetal. The subsequent exposure of these monomers to ring opening polymerisation conditions (using stannous octanoate) in the presence of ɛCL, yielded random copolymers with a functionalised polyester backbone. The acetal copolymer was successfully deproteceted and reduced to yield an alcohol pendant. A polymer – drug composite was successfully synthesised through the use of this alcohol polymer reacting with ciprofloxacin. A polymer – drug conjugate was also successfully synthesised using surface chemistry on PCL and PLA films. PCL and PLA films were cast as films and subsequently aminolysed using 1,6-hexamethylene diamine in aqueous media at pH = 11.5. These aminolysed films were then treated with both ciprofloxacin and penicillin G, together with amide coupling chemistry to synthesise biologically active surfaces. Ciprofloxacin and penicillin G were successfully attached to the PCL surface with ciprofloxacin being attached to the PLA variant. A functional PCL monomer was also successfully synthesised from the commercially available PCL diol. Both methacrylate and acrylate varients were synthesised through acid chloride chemistry. The acrylate and methacrylate analogue were UV cured using both type I (Irgacure 2959) and II (DETX/EDB) photoinitiators. The relative ratios of these initiators were changed along with the composition of the curing material to investigate curing parameters, to aid in 3D printing conditions. To achieve viscocity criteria for 3D printing a ratio of 70:30 (PCL DMA:PEG DA) was used, utilising PEG DA as a reactive diluent. A ratio of 3 wt% DETX and 3 wt% EDB was found to give the best UV curing results and were successfully applied on a jetting machine to yield 3D printed constructs.