3D Printing Enzyme Mediated Interpenetrating-Network Biohybrid Materials with Shape Changing Properties

Abstract

In this thesis, a novel shape-changing interpenetrating network-producing 3D bioink is described that is the combination of a calcium-crosslinked alginate network and an N,N′-methylenebisacrylamide-crosslinked poly(N-isopropylacrylamide) (PNIPAm) network . The printing protocol incorporates a bienzymatic initiation system, utilizing horseradish peroxidase and glucose oxidase, and is entirely performed at room temperature under aerobic conditions. The 3D structures produced using the ink retain the contractile thermosensitive properties of PNIPAm single networks, and certain printability metric performances of the ink are comparable to state-of-the-art commercial formulations. Also investigated and discussed are the ink’s print dimension limitations, property tunability, internal structure, and mechanical properties. Furthermore, the ink is inoculated with E. coli cells to produce 3D printable biohybrid materials and two functional prototypes are explored. The first is a bioremediation device capable of hydrolysing organophosphates via genetically engineered, phosphotriesterase- producing cells. The second prototype explored is an engineered living material, where the native redox activity of unmodified E. coli cells is integrated into the ink’s curing system. Living cell-initiation has previously not been combined with 3D bioprinting. As a further iteration, this second prototype material is repeated with modified E. coli cells, transformed to overexpress the artificial oxidoreductase, C45. Here, C45 is demonstrated to be capable of catalysing the formation of a polymeric material, which is the first example of a synthetic enzyme being able to do so.

Date of Award	25 Jan 2022
Original language	English
Awarding Institution	The University of Bristol
Supervisor	Adam W Perriman (Supervisor) & J L R Anderson (Supervisor)