Figure 2.

(A) Schematic representation of PEG functionalized GO synthesis through carboiimide formation. Reprinted with permission from Xu Z, Wang S, Li Y, Wang M, Shi P, Huang X. Covalent functionalization of grapheneoxide with biocompatible poly (ethylene glycol) for delivery of paclitaxel. ACS Appl MaterInterfaces. 2014;6(19):17268-17276. Copyright 2014 American Chemical Society.¹⁰ (B) Comparisons of GO and PEG functionalized GO through ATR-IR analysis. Reprinted with permission from Liu Z, Robinson JT, Sun X, Dai H. PEGylated nanographene oxide for delivery ofwater-insoluble cancer drugs. J Am Chem Soc. 2008;130(33):10876-10877. Copyright 2008 American Chemical Society.¹¹ (C) Elemental analysis of graphite powder, GO and GO-PEG showed presence of nitrogen in case of GO-PEG. Reprinted with permission from Xu Z, Wang S, Li Y, Wang M, Shi P, Huang X. Covalent functionalization of grapheneoxide with biocompatible poly (ethylene glycol) for delivery of paclitaxel. ACS Appl MaterInterfaces. 2014;6(19):17268-17276. Copyright 2014 American Chemical Society.¹⁰ (D) X-ray diffraction data of GO (blue line) and GO-PEG 4000 (green line). Reproduced from Kazempour M, Namazi H, Akbarzadeh A, Kabiri R. Synthesis and characterization of PEG-functionalized graphene oxide as an effective pH-sensitive drug carrier. Artif Cells, Nanomed, Biotechnol. 2019;47(1):90-94. Creative Commons license and disclaimer available from: http://creativecommons.org/licenses/by/4.0/legalcode.¹² (E) Stability of (a) GO and (b) PEGylated nanoscale GO (NGO-PEG) in different solutions i.e. PBS and cell medium after centrifugation at 10000g for 5 min. GO precipitated slightly in PBS and completely in cell medium and serum (a). NGO-PEG was found to be stable in all solutions (b); atomic force microscopic (AFM) images of (c) GO and (d) NGO-PEG. Reprinted with permission from Liu Z, Robinson JT, Sun X, Dai H. PEGylated nanographene oxide for delivery ofwater-insoluble cancer drugs. J Am Chem Soc. 2008;130(33):10876-10877.Copyright 2008 American Chemical Society.¹¹