(729h) Dipeptide-Based Polyphosphazene Polymers for Regenerative Engineering

The emergence of regenerative engineering has placed an important emphasis on the design of advanced biomaterials. There is a pressing need to produce different materials with a wide range of properties that can meet the ever-changing requirements of regenerative engineering and complex tissue regeneration. Biomaterials are an essential component of this innovative approach, and biodegradable polymers are gaining significant interest as scaffolds for tissue regeneration.

An ideal polymer for regenerative engineering should be biocompatible, have desired initial mechanical properties, should degrade in a controlled fashion timed to match the rate of tissue regeneration, have resorbable degradation products, be osteoconductive and allow for neovascularization. However, so far a polymer that can match all the properties listed above has not been ideally developed.

Polyphosphazenes offer a great platform for the design and synthesis of new biodegradable polymeric biomaterials with efficient control over degradation rate, mechanical properties, In vitro osteocompatibility, and In vivo biocompatibility.

Here, we report the synthetic design and physicochemical analysis of novel mixed substituent dipeptide-based polyphosphazene polymers using glycylglycine ethyl ester as the main substituent side group and co-substituting with phenylphenoxy and phenylalanine ethyl ester respectively. Poly [(glycine ethylglycinato)(phenylphenoxy)phosphazene](PNGEG-PhPh) and Poly[(ethyl phenylalanato)(glycine ethyl glycinato)phosphazene](PNEPA-GEG) with different side group compositions were synthesized via macromolecular nucleophilic substitution under anhydrous conditions. Structural analysis using ³¹P-NMR and FTIR identified the chemical structures of PNGEG-PhPh and PNEPA-GEG and confirmed the total replacement of chlorine atoms of the dichloro-polyphosphazene prepolymer with the nucleophilic side groups. Results from GPC, DSC, DMA, TGA, Contact angle analysis showed that the optimization of the side group chemistry of polyphosphazenes could yield polymers with a wide range of physicochemical properties such as glass transition temperatures, molecular weights, polydispersities, hydrophilicity/hydrophobicity, tensile modulus, and strength, etc. These novel peptide-based polymers have the potential to form a self-neutralizing blend with PLAGA.