Improving transport in hydrogels for 3D bioprinting applications

Abstract

Hydrogels are soft, water-based gels with widespread applications in medicine, tissue engineering, and biotechnology. Many of these applications require structuring hydrogels in three-dimensional space. Light-based 3D printers offer exquisite spatial control; however, technologies for light-based 3D-printing of hydrogels remain limited. This is mainly caused by poor material transportation through the hydrogel. For example, limited transport of oxygen and other nutrients through 3D printed tissue constructs containing living cells leads to low cell viability. Here, we describe three experimental research studies focused on improving material transport in 3D-printed hydrogels. In the first part of this thesis, we describe a generalizable method for light-based 3D printing of hydrogels containing open, well-defined, submillimeter-scale channels with any orientation. These submillimeter channels allow for bulk liquid flow through the hydrogel to improve nutrient and oxygen transport. In the second part of this thesis, we describe a simple, reversible, plug-based connector designed to couple tubing to a hydrogel-based fluidic device to allow for pressurized liquid flow through the system. The resulting connection can withstand liquid pressures significantly greater than traditional, connector-free approaches, enabling long-term flow through 3D-printed hydrogels. In the third part of this thesis, we characterize the printability of photopolymerizable resins containing particles that slowly dissolve to release oxygen and thereby improve cell viability. The light-based 3D bioprinting technologies we describe in this thesis will improve material transport through 3D printed hydrogels and enable a wide variety of applications in 3D bioprinting and hydrogel fluidics.