Polycaprolactone-based biodegradable copolymers of various architectures for incorporation into 3D printed hybrid bone scaffolds
File(s)
Author(s)
Iqbal, Haffsah
Type
Thesis
Abstract
Regeneration of bone defects arising from trauma, fractures, or tumor resections is possible with synthetic bone graft materials. However, there is still an unmet need for the regeneration of large defects. Polymeric scaffolds have been designed with open porosities, degradability, and the capability to administer biotherapeutics to encourage new bone ingrowth. However, biodegradable polymers have poor mechanical properties, which can be addressed by adding reinforcement made of more biocompatible materials. Three-dimensional (3D) printing technologies have developed over the past 20 years, but many printing technologies are limited in the materials they can print. Biodegradable synthetic polymers can break down through hydrolysis and be absorbed in vivo and are commonly used in medical devices, such as sutures, but their degradation rates are not appropriate for structural scaffold applications. Bioglass is a bioactive glass that can bind to host bone and promote bone regeneration, but they are brittle. Inorganic/organic hybrids that consist of silica networks and organic polymers interacting at the nanoscale can deliver a synergy of properties. In this thesis, hybrids were based on silica, poly(caprolactone) (PCL) and methacrylate monomers. Organic networks were synthesised from copolymers of PCL-2OH, PCL-3OH, PCL-4OH, methyl methacrylate, and 3-(trimethoxysilyl)propyl methacrylate through reversible-addition fragmentation and ring opening polymerisation techniques to produce well-defined polymers. In addition, different polymer architectures of linear randomly and star-like copolymers were synthesized and introduced to class II hybrids (covalent bonds forming between the silica and organic networks) via the sol-gel process. The new hybrids were able to outperform bioactive glass and previous hybrids in terms of mechanical properties. Copolymers were used as hybrid ink to fabricate 3D printed scaffolds with pore size for bone regeneration application. In addition, bone forming cells were able to adhere and proliferate on the hybrids.
Version
Open Access
Date Issued
2023-03-15
Date Awarded
01/10/2023
License URL
Advisor
Jones, Prof. Julian R.
Georgiou, Prof. Theoni
Sponsor
Punjab Educational Endowment Fund
Publisher Department
Materials
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)