Cellulose derived carbon dots
From synthesis to evaluation as multifunctional building blocks in biomedical scaffolds
Time: Fri 2021-04-16 10.00
Subject area: Fibre and Polymer Science
Doctoral student: Nejla Benyahia Erdal , Polymerteknologi
Opponent: Professor Jukka Seppälä, Aalto-universitetet
Supervisor: Professor Minna Hakkarainen, Polymerteknologi, Fiber- och polymerteknologi, Polymerteknologi
The implementation of biobased and biodegradable polymeric materials in biomedical applications is often coupled with issues related to their insufficient mechanical properties or limited bioactivity. In this thesis, a perspective on valorization of biomass is presented, demonstrating the transformation of cellulose into biobased carbon nanomaterials with the potential to serve as multifunctional property enhancers in polycaprolactone (PCL) scaffold materials for tissue engineering.
Firstly, nanographene oxide (nGO) type of carbon dots were produced through a microwave assisted hydrothermal carbonization of cellulose and subsequent oxidation in an acidic environment. The carbon dots demonstrated zero-dimensional (0D) character, ample amount of oxygen functionalities and fluorescence properties. Furthermore, a green reduction process in superheated water was developed to reduce the nGO carbon dots with and without the aid of a green reducing agent, caffeic acid (CA). The resulting r-nGO and r-nGO-CA showed in contrast to nGO decreased oxygen content and enhanced thermal stability. r-nGO-CA, in addition, maintained good cell viability towards osteoblast-like cells at a higher concentration than nGO.
Secondly, incorporation of r-nGO or r-nGO-CA in PCL nanocomposites induced great enhancement in mineralization capability and creep resistance. nGO carbon dots could also due to their oxygen-rich content, be utilized to modify 3D scaffolds through surface functionalization and blending. The nGO on the surface of the PCL scaffolds, produced through optimized solvent casting particulate leaching (SCPL) techniques, could act as anchor sites for antibiotic loading and induce mineralization. It was also shown that incorporation of nGO in PCL scaffolds fabricated through high internal phase emulsion (HIPE) templating influenced the macrostructure of the scaffolds further manifesting the versatility and potential of the fabricated biobased carbon dots in biomedical applications.