Engineering long-term controlled drug release from biodegradable devices 3D printed with vat polymerization

Vat polymerization (VP) 3D printing with biodegradable resins has recently emerged as a potential method to fabricate patient specific drug delivery devices. The unique advantage of VP printing is the ability to print complex geometries with high resolution and intricate details that can offer a high level of control of drug release kinetics. However, non-degrading and slow-degrading photoreactive resins are often used to print these devices as fast degradation of the device can lead to uncontrolled drug release rates. Therefore, drug release from these devices often tends to be Fickian or diffusion-controlled in that drug release gradually decreases over time. Some studies have shown that device degradation could be an advantage in controlled release, but there is currently no fundamental understanding on how it can be utilized to control long-term drug release from 3D-printed devices. In this study, we employ VP 3D printing of relatively fast degrading polyester resins loaded with surrogate drug rhodamine b (RhB) as a model system to investigate the role of degradation in achieving controlled drug release. Degradation of the resulting devices was modified by varying key geometric parameters such as surface area to volume ratio, strut beam size, and pore size and the effect of these parameters on the release on RhB was determined. The results revealed that print geometry affected the degradation of devices, and long-term controlled release of RhB could be achieved by modifying print geometry. It was also implied that onset of degradation-controlled release could be a crucial factor in achieving constant drug release. The insights obtained from these studies provide a better understanding of how 3D printing with biodegradable resins can be applied towards the engineering of long-term controlled release from clinically relevant devices.