Physicochemical characteristics of pristine and functionalized graphene

Abstract

Graphene-based nanomaterials have received significant attention in the last decade due to their interesting properties. Its electrical and thermal conductivity and strength make graphene well suited for a variety of applications, particularly for use as a composite material in plastics. Furthermore, much work is taking place to utilize graphene as a biomaterial for uses such as drug delivery and tissue regeneration scaffolds. Owing to the rapid progress of graphene and its potential in many marketplaces, the potential toxicity of these materials has garnered attention. Graphene, while simple in its purest form, can have many different chemical and physical properties. In this paper, we describe our toxicity evaluation of pristine graphene and a functionalized graphene sample that has been oxidized for enhanced hydrophilicity, which was synthesized from the pristine sample. The samples were characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, infrared spectroscopy, thermogravimetric analysis, zeta-potential, atomic force microscopy and electron microscopy. We discuss the disagreement between the size of imaged samples analyzed by atomic force microscopy and by transmission electron microscopy. Furthermore, the samples each exhibit quite different surface chemistry and structure, which directly affects their interaction with aqueous environments and is important to consider when evaluating the toxicity of materials both in vitro and in vivo.

Cytotoxicity profile of pristine graphene on brain microvascular endothelial cells

“…The PG used in this study exhibited characteristics consistent with the manufacturer's technical details with a low oxygen content (~2.5%) and dimensions of 1‐1.2 nm thick and <10 μm lateral dimensions. By our own analysis as reported previously (Bourdo et al, ; Majeed et al, ), it was determined by X‐ray photoelectron spectroscopy that the PG exhibited an elemental composition of about 97% C and 2.5% O. The lateral size of the PG was between approximately 50 and 1750 nm, while a thickness of ~2 nm for the thinnest sections was observed.…”

“…The unmodified PG as used in this study had been extensively characterized by multiple instrumental techniques revealing their physicochemical properties by Majeed et al (Majeed et al, ) and Bourdo et al (Bourdo et al, ). The PG used in this study exhibited characteristics consistent with the manufacturer's technical details with a low oxygen content (~2.5%) and dimensions of 1‐1.2 nm thick and <10 μm lateral dimensions.…”

In vivo noninvasive analysis of graphene nanomaterial pharmacokinetics using photoacoustic flow cytometry

“…Upon chemical treatment (Majeed et al, 2016), functionalized graphene was decorated with some hydrophilic alcohol and carboxylic acid groups, that rendered them less hydrophobic and had fewer large clusters. X-ray photoelectron spectroscopy analysis (Majeed et al, 2016;Bourdo et al, 2017) demonstrated a~6.63 ± 0.14% oxygen content increase compared to~2.5% for initial graphene powder. Graphene oxide (≤ 46% of oxygen, manufacturer data, Suppporting Information Table 1) was finely dispersed in water and formed a stable suspension in water without any significant precipitation observed over more than 2 years of shelf storage.…”

Graphene-based 2D constructs for enhanced fibroblast support

“…Low-and high -oxygen graphene sample preparation. The low-and high-oxygen graphene samples were prepared according to previously reported methods [18,21,36].…”