Synthesis of double-clickable functionalised graphene oxide for biological applications

Abstract

Azide- and alkyne-double functionalised graphene oxide (Click² GO) was synthesised and characterised with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA) and Raman spectroscopy. Fourteen-percentage increase in azide content was found, after pre-treatment of GO with meta-chloroperoxybenzoic acid (mCPBA), determined with elemental analysis. No effect on A549 cell viability was found, up to 100 μg mL⁻¹ and 72 h of incubation, determined with the modified lactate dehydrogenase (mLDH) assay. Two sequential copper(I) catalysed azide–alkyne cycloaddition (CuAAC) reactions were performed to conjugate the propargyl-modified blood–brain barrier targeting peptide Angiopep-2, and a bis-azide polyethylene glycol (M_W = 3500), to the Click² GO. The final conjugate was characterised with ATR-FTIR and TGA.