Graphene oxide and its derivatives as promising In-vitro bio-imaging platforms

Intrinsic fluorescence and versatile optical properties of Graphene Oxide (GO) in visible and near-infrared range introduce this nanomaterial as a promising candidate for numerous clinical applications for early-diagnose of diseases. Despite recent progresses in the impact of major features of GO on the photoluminescence properties of GO, their modifications have not yet systematically understood. Here, to study the modification effects on the fluorescence behavior, poly ethylene glycol (PEG) polymer, metal nanoparticles (Au and Fe₃O₄) and folic acid (FA) molecules were used to functionalize the GO surface. The fluorescence performances in different environments (water, DMEM cell media and phosphate buffer with two different pH values) were assessed through fluorescence spectroscopy and fluorescent microscopy, while Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) and Scanning electron microscopy (SEM) were utilized to evaluate the modifications of chemical structures. The modification of GO with desired molecules improved the photoluminescence property. The synthesized platforms of GO-PEG, GO-PEG-Au, GO-PEG-Fe₃O₄ and GO-PEG-FA illustrated emissions in three main fluorescence regions (blue, green and red), suitable for tracing and bio-imaging purposes. Considering MTT results, these platforms potentially positioned themselves as non-invasive optical sensors for the diagnosis alternatives of traditional imaging agents.