(267e) Effect of Molecular Weight and Degree of Functionality on Degradation, Biocompatibility and Two-Photon Polymerization of Acrylated Poly(caprolactone)

Effect of molecular weight and degree of functionality on degradation, biocompatibility and two-photon polymerization of acrylated poly(caprolactone)

Brian J. Green,¹ Jessica R. Thompson,² Kristan S. Worthington,² C. Allan Guymon,¹ Budd A. Tucker²

¹Department of Chemical and Biochemical Engineering, The University of Iowa, 4133 Seamans Center, Iowa City, IA 52242, USA

²Wynn Institute of Vision Research, Department of Ophthalmology and Visual Science, Carver College of Medicine, The University of Iowa, 4111 Medical Education and Research Facility, Iowa City, IA 52242, USA

Tissue scaffolds are materials that provide structure capable of supporting cell growth for tissue engineering applications. An ideal scaffold has properties that are application specific and must be tailored for individual cell and tissue types, making polymeric materials especially viable because of the broad range of chemistries and material properties available. Additionally, precise control of scaffold structure in three-dimensions is integral for the design of effective scaffolds. One area in which advanced tissue scaffolds are needed is reversing retinal degeneration associated with age-related and inherited eye diseases. These diseases cause the loss or death of photoreceptor cells, cells that the human body is incapable of regenerating. Stem cell therapy is a promising approach to replacing the degenerate cells, but scaffolds capable of directing the delivery and proliferation of stem cells in three-dimensions must be designed to effectively restore vision.

In this research, we functionalize poly(caprolactone) (PCL), a degradable polymer commonly used in biomedical applications, with acrylate groups to enable photopolymerization and two-photon lithography, a fabrication method that allows precise control by utilizing photopolymerization to create 3D structures with features as small as 100 nm. To fully understand the effects of PCL molecular weight and number of functional groups on each monomer, a number of properties were measured. Reaction kinetics and functional group conversion were used to determine suitability for 3D printing and confirmed by printing structures and measuring the polymerization threshold and resolution. Polymer degradation profile, mechanical properties, and biocompatibility were then used to determine the monomer from which large scaffold structures would be fabricated. It was found that lower molecular weight PCL monomers with a higher number of functional groups had the fastest reaction kinetics and subsequently the highest suitability for 3D printing scaffolds using two-photon lithography. Of the monomers best suited to 3D printing, the higher molecular weight monomer had more desirable mechanical properties, degradation rate, and similar biocompatibility and was therefore selected to fabricate large-scale retinal tissue scaffolds.