High-Concentration Aqueous Dispersions of Graphene Using Nonionic, Biocompatible Block Copolymers

Abstract

The ability to disperse pristine graphene at high concentrations in aqueous solutions is an enabling step for large-scale processing and emerging biomedical applications. Herein we demonstrate that nonionic, biocompatible block copolymers are able to produce graphene dispersions with concentrations exceeding 0.07 mg mL À1 via sonication and centrifugation, resulting in optical densities above 4 OD cm À1 in the visible and nearinfrared regions of the electromagnetic spectrum. The dispersion efficiency of graphene using Pluronic and Tetronic block copolymers varies substantially depending on the lengths of their hydrophilic and hydrophobic domains, with the best of these copolymers sharing similar domain molecular weight ratios and comparable overall molecular weights. This study presents a new class of biocompatible dispersing agents for graphene in aqueous solution, thus suggesting a facile route to employ graphene in biomedical sensing, imaging, and therapeutic applications. SECTION: Nanoparticles and Nanostructures

Successful Stabilization of Graphene Oxide in Electrolyte Solutions: Enhancement of Biofunctionalization and Cellular Uptake

“…In contrast to previous reports, 26,28 where very large amounts of amphiphilic block copolymers were used to disperse only a small mass of hydrophobic graphene or reduced graphene oxide sheets in pure water , the hydrophilic nature of graphene oxide nanosheets enables a dramatic reduction in the mass of Pluronic F127 required for their stabilization in the presence of a high concentration of electrolytes . Most importantly, the great range of media dispersibility afforded by our two stabilization strategies allows the stabilized graphene oxide nanosheets to undergo highly efficient bio-conjugation to proteins and nucleic acids than untreated graphene oxide.…”

Thickness sorting of two-dimensional transition metal dichalcogenides via copolymer-assisted density gradient ultracentrifugation

“…In particular, F68 is composed of a central hydrophobic polypropylene oxide (PPO) unit surrounded by hydrophilic polyethylene oxide chains (Fig. 1a), and is known to be effective as an amphiphilic dispersant for graphene 31 and DGU separation of carbon nanotubes 30 . To estimate the buoyant density of F68-encapsulated MoS 2 , the parameters in the aforementioned model are modified as following: m surf ¼ 1.40 Â 10 À 20 g is the mass of one F68 molecule, t A ¼ 1.6 nm, t H ¼ 20.6 nm and s is varied between 0.058 and 0.575 nm À 2 to account for the two likely extremes where the surface coverage of PPO chains on the MoS 2 surface ranges from 10-100%.…”

Pluronic F108 Coating Decreases the Lung Fibrosis Potential of Multiwall Carbon Nanotubes by Reducing Lysosomal Injury

“…25, 29 Because this dispersal depends on the tube dimensions and the lengths of the polymeric chains, theoretical calculations and experimental data have confirmed that copolymers with longer hydrophilic segments are better dispersants than polymers with shorter hydrophilic chains. 31–34 For this reason, we chose Pluronic F108, which exhibits longer PEO blocks than F127 to perform the tube dispersals for this study. 29 In order to obtain the best possible understanding of the functional effect of PF108 dispersion, we used two dispersal methods, one in which the MWCNTs are dispersed by addition of PF108, without further purification, and the second using an additional centrifugation step to remove tube aggregates and therefore yield purified and more homogeneously dispersed tubes (Figure 1).…”