Open in another window Graphene-based nanomaterials have seduced tremendous interest within
Open in another window Graphene-based nanomaterials have seduced tremendous interest within the last decade because of their unique electronic, optical, mechanical, and chemical properties. RGO and Move have already been reported to have the ability to connect to several substances, such as for example doxorubicin (DOX) and polyethylenimine (PEI), and also have been accepted as excellent systems for medication gene and delivery transfection.9?16 Surface area engineering of graphene-based nanomaterials has played an essential role within their biomedical applications.7,8,17 For instance, suitable PEGylation cannot only enhance the biocompatibility and solubility of Move, but also reduce its potential toxicity in vitro aswell such as vivo.18?20 After integration with other functional nanoparticles, such as for example magnetic iron oxide nanoparticles (IONPs),21?24 silver nanoparticles,25?27 and quantum dots (QDs),28?30 functionalized RGO and GO also have proven great prospect of simultaneous cancer imaging and therapy in little animals.30?34 BMS-777607 cost Using the conjugation of well-selected focusing on ligands, tumor targeted Move (or RGO) has recently shown significantly improved tumor accumulation in various cancer designs in vivo.35?37 Structure 1 summarizes representative functions of surface area functionalization of RGO and GO. In this section, we will concentrate on surface area executive of RGO and Choose biomedical applications. Open in BMS-777607 cost another window Structure 1 Schematic Illustration of Functionalization of Graphene-Based NanomaterialsReproduced with authorization from ref (17). Synthesis of Graphene-Based Nanomaterials Generally, two strategies have been created for the formation of graphene. The first method is a top-down approach, which could cleave multilayer graphite into single layers BMS-777607 cost via mechanical, physical, or chemical exfoliation.38?40 The second method is a bottom-up approach, wherein graphene could be obtained by chemical vapor deposition of one-layer carbon onto well-selected substrates.41?43 So far, oxidative exfoliation via the Hummers method (developed by Hummers and Offeman in 1950s) is the most popular method for the generation of graphene derivatives, such as GO, with great output.44 This technique involves the oxidative exfoliation of graphite using a mixture of potassium permanganate (KMnO4) and concentrated sulfuric acid (H2SO4). As-produced GO is highly oxidized with a large number of residual epoxides, hydroxides and carboxylic acid groups on its surface. To restore the structure and properties of graphene, GO could be further reduced to obtain RGO by reacting with well-selected reducing agents (e.g., N2H4).45 In comparison with GO, RGO is known to have increased BMS-777607 cost conductive and optical absorbance, making it a more attractive agent for future cancer photothermal therapy.31 For more detailed information about the synthesis of graphene-based nanomaterials, readers are referred to these excellent review papers.40,41 Surface Engineering of Graphene-Based Nanomaterials To Improve Biocompatibility As we have mentioned, GO has abundant Rabbit Polyclonal to GPR37 epoxides, hydroxides, and carboxylic acid groups on its surface, which makes it possible for covalent surface functionalization based on these reactive groups. Polyethylene glycol (PEG) is among the most widely used for improving the solubility and biocompatibility of graphene derivatives.18,46,47 By using amine-terminated branched PEG, successful PEGylation of GO has been reported (Figure ?(Figure11A).10 Intensive sonication was first introduced to break larger GO (size range: 50C500 nm) down to nanographene oxide (nGO) with a significantly reduced size range (i.e., 5C50 nm) (Figure ?(Figure1B).1B). Six-armed branched PEG was then covalently linked to the carboxylic acid groups on nGO using well-established EDC (1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide)/NHS (for 5 min. GO crashed out slightly in PBS and completely in cell medium and serum while nGO-PEG was stable in all solutions. Reproduced with permission from ref (10 and 17). Many other hydrophilic polymers, including poly(l-lysine) (PLL),53 poly(acrylic acid) (PAA),54 dextran,55,56 and chitosan,57?60 have also been studied for surface functionalization of GO. In one study, GO was functionalized with PLL by stirring GO solution with PLL in the presence of potassium hydroxide (KOH), and subsequently treated with sodium borohydride (NaBH4).53 As-synthesized PLL functionalized GO showed high solubility and biocompatibility, and contained plentiful.