Year

2019

Degree Name

Biofabrication

Department

School of Medicine

Abstract

Bioresorbable stents promised the restoration of the coronary blood flow without the long-term complications of their non-resorbable counterparts. Although maintaining coronaries open using bioresorbable stents for prolonged periods has proven challenging, using biodegradable polymeric composite materials could potentially solve this issue. To fabricate these polymeric structures, additive manufacturing may provide an accessible and customizable platform. This research examines the development of a novel customized dual-printhead bioprinter that was utilised for 3D printing polymer-based stents incorporating graphene composites.

The customized bioprinter was used to 3D print stents from polycaprolactone (PCL) and PCL graphene-based composites. Graphene oxide (GO) and edge functionalized graphene (EFG) were used as fillers to develop appropriate composites for fabrication of single- or hybrid-material architectures.

Single-material stents fabricated using PCL/EFG composites outperformed PCL/GO 1% and blank PCL stents. PCL/EFG 1% stents showed an increased radial strength by 27% and tensile strength by 23% compared to blank PCL stents. PCL/EFG 5% stents showed higher radial strength by 36% compared to blank PCL stents. Hybrid material stents using PCL and PCL/EFG 1% were subjected to mechanical property testing, degradation tests and used as a drug-delivery platform. Hybrid-material stents compressive and tensile strength were inferior compared to single-material stents, which might be improved through further optimization.

Enzymatically degraded hybrid stents were found to be bioresorbable with a rate slower than previously reported for PCL. Drug delivery capabilities of hybrid stents were studied using paclitaxel-loaded stents. Hybrid stents showed a slower cumulative drug release by 36% against blank PCL stents.

These results demonstrated the feasibility of a stent bioprinter and the improvement of mechanical properties with the use of EFG composites while preserving bioresorbable and drug-delivery capabilities.

FoR codes (2008)

0903 BIOMEDICAL ENGINEERING, 0906 ELECTRICAL AND ELECTRONIC ENGINEERING, 0910 MANUFACTURING ENGINEERING, 0912 MATERIALS ENGINEERING

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.