Plasma surface engineering of porous materials for biomedical applications

Abstract

Three-dimensional (3D) porous scaffolds are essential in tissue engineering by replicating tissue structures and biochemical cues, often requiring decorating scaffold surfaces with essential biomolecules. However, physical adsorption often results in unstable attachment while wet-chemistry covalent attachment introduces process complexity and toxicity. Plasma surface treatment offers an alternative by covalently immobilising biomolecules in a single-step, solvent-free process. However, plasma cannot effectively penetrate small pores, presenting a significant challenge for intricate, porous tissue-mimicking materials.

This thesis developed plasma processes to modify high surface area to volume ratio (HSAV) materials for their biofunctionalisation. The development initially focused on pack-bed plasma ion implantation to directly generate plasma inside porous polymeric scaffolds, enabling internal plasma surface modification. The obtained knowledge was then extended to ceramics and tubes. Spectroscopy techniques, including X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and time-of-flight secondary ion mass spectrometry, confirmed homogeneous surface modification throughout the HSAV materials. Enzyme linked immunosorbent assay and fluorescent imaging showed homogeneous covalent immobilisation of biomolecules on the plasma-activated HSAV materials. The biomolecule-functionalised HSAV materials exhibited excellent ability to modulate cellular behaviours for mesenchymal stem cell expansion, bone tissue engineering, organ-on-a-chip devices, and vascular tissue engineering.

This thesis demonstrated the efficacy of the novel plasma process in surface-modifying HSAV materials across various materials and structures, significantly enhancing their biofunctionality in tissue engineering. This technology lays the foundation for developing advanced biofunctional HSAV materials for tissue engineering and holds potential for broader applications.