(742b) A Polyester Based Photoluminescent Hydrogel As Extracellular Matrix Mimics

Photoluminescent hydrogels have emerged as 3D materials with potential applications in many fields such as imaging, tissue engineering, and drug delivery. Current photoluminescent hydrogels are fabricated by either conjugating or doping a fluorescent dye, fluorescent protein, lanthanide chelate or quantum dot into polymeric hydrogel matrix. Their scope of applications has been severely limited by drawbacks such as poor photostability or substantial toxicity. There is an urgent need for a synthetic hydrogel with degradable, injectable, biocompatible and photoluminescent properties, but a successful development has not yet been reported. Herein, we report a successful development of biodegradable and photoluminescent hydrogel with synthetic polymers. A series of polyester oligomers with tunable intrinsically fluorescent properties have been successfully synthesized from biocompatible monomers including citric acid, poly(ethylene glycol) (PEG)-diol and various amino acids via a facile polycondensation reaction. The synthesized oligomers were further modified by introducing multiple thiol functional groups using a high efficient enzyme assisted transesterification reaction. A library of hydrogels with diverse physiochemical properties can be formed by combining thiol group functionalized polymers with different molecular weight multi-armed PEG acrylates or PEG maleimides through a convenient Michael addition reaction. Preliminary data show that the chemical, optical, mechanical and biological properties of the intrinsically photoluminescent hydrogels can be tuned by changing a series of parameters such as gel composition, ionic strength, polymer molecular weight, gel forming temperature or pH. The hydrogel can be further modified with an extracellular matrix (ECM) moiety to mimic ECM microenvironment for cell growth and tissue formation. The hydrogel shows good biocompatibility when cultured with NIH 3T3 cells. We then conducted in vivo florescence bioimaging of the hydrogels that were injected under the skin of nude mice to demonstrate their potential use in injectable biomaterials and noninvasive implant tracking.