Poly(ethylene glycol)-Engrafted Graphene Oxide for Gene Delivery and Nucleic Acid Amplification

Graphene oxide (GO) is an oxidized form of graphene accommodating various oxygen-containing functional groups such as hydroxyl, epoxy, and carboxyl groups on its surface. GO has been extensively utilized in various biomedical applications including the delivery of biomolecules and the development of biosensors owing to its beneficial properties such as high surface area, nucleic acid adsorption, and fluorescence quenching through fluorescence resonance energy transfer (FRET). However, despite these favorable properties, the direct utilization of GO in these applications is often limited by low dispersibility in a physiological medium, cytotoxicity, low biocompatibility, and a strong binding affinity of nucleic acids to GO surface. The large surface area of GO and the presence of various functional groups on its surface make it highly amenable to facile surface modifications, offering scope for GO surface functionalization to overcome these limitations. When polyethylene glycol (PEG), which is a biocompatible polymer, is conjugated to GO, the PEGylated GO enhances the biocompatibility and dispersibility, reduces cytotoxicity, and allows controlled drug delivery with controllable binding affinity towards nucleic acid. PEG-engrafted GO retains the beneficial properties of GO while effectively addressing its limitations, rendering it suitable for various biomedical applications. In this review, we present the recent advancements of PEGylated GO in gene/drug delivery and the facilitation of nucleic acid amplification techniques, which aid in the development of therapeutic and diagnostic tools, respectively.