Fabrication and funtionalization of rGO containing polymeric materials

Abstract

In recent years, rGO-containing polymeric materials have been utilized in various biomedical applications such as targeted drug delivery, protein release and photothermal therapy due to the characteristic properties of rGO such as high mechanical stability, large surface area, thermal and optical conductivity. Incorporation of rGO can be done by their encapsulation within polymeric materials, as well as through their functionalization with polymers. In the first part of this thesis, rGO-containing hydrogels for “on-demand” protein release were developed. Hydrogels were synthesized using the fast thiol-maleimide “click” reaction, while the Diels-Alder (DA) cycloadduct of furan-maleimide was introduced into the hydrogel network to impart thermo-responsiveness. Incorporation of rGO into the hydrogel matrix made it possible to release a cargo such as protein or dye-conjugated macromolecule under Near-Infrared Light (NIR) activation, since rGO is a photothermal agent that converts light-to-heat. This rapid light-to-heat conversion results in heating of the hydrogel, leading to the retro-DA reaction of endo-linkages, resulting in hydrogel network degradation. Successful synthesis of polymeric precursors, fabrication of photothermally responsive hydrogels, and their degradation and release of dye-conjugated macromolecules is reported. In the second part of this thesis, rGO surface was modified with small molecule and PEG-based ligands containing a pyridyldisulfide (PDS) group, to enable surface functionalization through the thiol-disulfide exchange reaction. To this end, rGO surface was modified with pyrene- and PDS-containing molecules. The π-π interactions between rGO and pyrene was used to functionalize rGO through a non-covalent interaction. Thereafter, using the PDS groups on the rGO, conjugation of thiol-containing ligands such as ferrocene-thiol was achieved.