3D printing of scaffolds for liver-on-chip (using two-photon polymerization)

Abstract

The development of new drugs requires improved cell culture models that can accurately replicate the complexity of the human liver. One of the most promising models to address this challenge is Liver-On-Chip (LOC) systems. This thesis investigates the viability and functionality of hepatocytes (HepG2 cells) in 3D printed scaffolds for LOC applications. The study focuses on
using two-photon polymerization (2PP) printing technology to fabricate high-resolution scaffolds and assess their performance. Different 3D designs of scaffolds structures were fabricated using two 2PP resins: Ormocomp and Bioinx Hydrotech INX N200. The mechanical stability of the printed structures was optimized through experimental evaluation of the printed structures in an iterative process. The biocompatibility and functionality of the printed scaffolds were then assessed using HepG2 cells. Cytotoxicity tests confirmed the biocompatibility of the 2PP resins, while functionality tests demonstrated the superior performance of the cells in the Ormocomp scaffolds. The effects of cell culture coatings such as laminin and collagen on cell adhesion and functionality
were also investigated. Furthermore, Raman spectroscopy was used to characterize the printed scaffolds and cells. First, a spectral analysis of the 2PP materials and HepG2 cells is performed. Then, 2D Raman maps of scaffold-cell systems were obtained using principal component analysis (PCA). The results demonstrated the potential of Raman spectroscopy in differentiating between materials and cells. While scaffold signals posed challenges in the analysis, gold coating was proved effective in signal elimination.
The results of this study contribute to the understanding of cell viability and functionality in 2PP 3D-printed scaffolds for LOC applications. The research highlights the importance of scaffold design, material selection, and cell culture coatings in achieving optimal cell performance. The study suggests further improvements in scaffold structures and alternative coatings for enhanced
cell adhesion and functionality, particularly for Hydrotech INX N200.

Date of Award	2023
Original language	English