Effects of sunlight on the fate of graphene oxide and reduced graphene oxide nanomaterials in the natural surface water.

Graphene nanomaterials have been commercialized for use in the electronic and biomedical industries, increasing their dissemination into surface waters and subsequent transformation in natural aquatic environment. While the photodegradation of graphene oxide nanomaterials has been investigated in the past, previous research did not consider actual natural aquatic environment and also focused on primarily graphene oxide nanomaterials. In this study, photodegradation of graphene nanomaterials with varying oxidation levels, including graphene oxide (GO) and partially reduced graphene oxide (rGO-2 h) are evaluated in Columbia River Water and compared with each other.

Lateral size of graphene oxide determines differential cellular uptake and cell death pathways in Kupffer cells, LSECs, and hepatocytes.

As a representative two-dimensional (2D) nanomaterial, graphene oxide (GO) has shown high potential in many applications due to its large surface area, high flexibility, and excellent dispersibility in aqueous solutions. These properties make GO an ideal candidate for bio-imaging, drug delivery, and cancer therapy. When delivered to the body, GO has been shown to accumulate in the liver, the primary accumulation site of systemic delivery or secondary spread from other uptake sites, and induce liver toxicity.

Dissolution of 2D Molybdenum Disulfide Generates Differential Toxicity among Liver Cell Types Compared to Non-Toxic 2D Boron Nitride Effects.

2D boron nitride (BN) and molybdenum disulfide (MoS ) materials are increasingly being used for applications due to novel chemical, electronic, and optical properties. Although generally considered biocompatible, recent data have shown that BN and MoS could potentially be hazardous under some biological conditions, for example, during, biodistribution of drug carriers or imaging agents to the liver. However, the effects of these 2D materials on liver cells such as Kupffer cells (KCs), liver sinusoidal endothelial cells, and hepatocytes, are unknown.

Aggregation morphology of planar engineered nanomaterials.

In this investigation, the utility of a static light scattering (SLS) technique to characterize aggregate morphology of two-dimensional engineered nanomaterials (2D ENMs) was systematically evaluated. The aggregation of graphene oxide (GO) and lithiated-molybdenum disulfide (Li-MoS) were measured and compared to that of a spherical reference colloid, carboxylate-modified latex (CML) nanoparticles. The critical coagulation concentration (CCC) for all dispersions was determined via analysis of aggregation kinetics using time-resolved dynamic light scattering.

Assessing and Mitigating the Hazard Potential of Two-Dimensional Materials.

The family of two-dimensional (2D) materials is comprised of a continually expanding palette of unique compositions and properties with potential applications in electronics, optoelectronics, energy capture and storage, catalysis, and nanomedicine. To accelerate the implementation of 2D materials in widely disseminated technologies, human health and environmental implications need to be addressed. While extensive research has focused on assessing the toxicity and environmental fate of graphene and related carbon nanomaterials, the potential hazards of other 2D materials have only recently begun to be explored.

Toxicological Profiling of Highly Purified Single-Walled Carbon Nanotubes with Different Lengths in the Rodent Lung and Escherichia Coli.

Carbon nanotubes (CNTs) exhibit a number of physicochemical properties that contribute to adverse biological outcomes. However, it is difficult to define the independent contribution of individual properties without purified materials. A library of highly purified single-walled carbon nanotubes (SWCNTs) of different lengths is prepared from the same base material by density gradient ultracentrifugation, designated as short (318 nm), medium (789 nm), and long (1215 nm) SWCNTs.

Three-Dimensional Printing of Cytocompatible, Thermally Conductive Hexagonal Boron Nitride Nanocomposites.

Hexagonal boron nitride (hBN) is a thermally conductive yet electrically insulating two-dimensional layered nanomaterial that has attracted significant attention as a dielectric for high-performance electronics in addition to playing a central role in thermal management applications. Here, we report a high-content hBN-polymer nanocomposite ink, which can be 3D printed to form mechanically robust, self-supporting constructs. In particular, hBN is dispersed in poly(lactic- co-glycolic acid) and 3D printed at room temperature through an extrusion process to form complex architectures.

Surface Oxidation of Graphene Oxide Determines Membrane Damage, Lipid Peroxidation, and Cytotoxicity in Macrophages in a Pulmonary Toxicity Model.

While two-dimensional graphene oxide (GO) is used increasingly in biomedical applications, there is uncertainty on how specific physicochemical properties relate to biocompatibility in mammalian systems. Although properties such as lateral size and the colloidal properties of the nanosheets are important, the specific material properties that we address here is the oxidation state and reactive surface groups on the planar surface. In this study, we used a GO library, comprising pristine, reduced (rGO), and hydrated GO (hGO), in which quantitative assessment of the hydroxyl, carboxyl, epoxy, and carbon radical contents was used to study the impact on epithelial cells and macrophages, as well as in the murine lung.

Optothermally Reversible Carbon Nanotube-DNA Supramolecular Hybrid Hydrogels.

Supramolecular hydrogels (SMHs) are three-dimensional constructs wherein the majority of the volume is occupied by water. Since the bonding forces between the components of SMHs are noncovalent, SMH properties are often tunable, stimuli-responsive, and reversible, which enables applications including triggered drug release, sensing, and tissue engineering. Meanwhile, single-walled carbon nanotubes (SWCNTs) possess superlative electrical and thermal conductivities, high mechanical strength, and strong optical absorption at near-infrared wavelengths that have the potential to add unique functionality to SMHs.

Comprehensive Enhancement of Nanostructured Lithium-Ion Battery Cathode Materials via Conformal Graphene Dispersion.

Efficient energy storage systems based on lithium-ion batteries represent a critical technology across many sectors including consumer electronics, electrified transportation, and a smart grid accommodating intermittent renewable energy sources. Nanostructured electrode materials present compelling opportunities for high-performance lithium-ion batteries, but inherent problems related to the high surface area to volume ratios at the nanometer-scale have impeded their adoption for commercial applications. Here, we demonstrate a materials and processing platform that realizes high-performance nanostructured lithium manganese oxide (nano-LMO) spinel cathodes with conformal graphene coatings as a conductive additive.

Identification and Optimization of Carbon Radicals on Hydrated Graphene Oxide for Ubiquitous Antibacterial Coatings.

While the antibacterial properties of graphene oxide (GO) have been demonstrated across a spectrum of bacteria, the critical role of functional groups is unclear. To address this important issue, we utilized reduction and hydration methods to establish a GO library with different oxidation, hydroxyl, and carbon radical (•C) levels that can be used to study the impact on antibacterial activity. Using antibiotic-resistant bacteria as a test platform, we found that the •C density is most proximately associated with bacterial killing.

Toxicological Profiling of Highly Purified Metallic and Semiconducting Single-Walled Carbon Nanotubes in the Rodent Lung and E. coli.

The electronic properties of single-walled carbon nanotubes (SWCNTs) are potentially useful for electronics, optics, and sensing applications. Depending on the chirality and diameter, individual SWCNTs can be classified as semiconducting (S-SWCNT) or metallic (M-SWCNT). From a biological perspective, the hazard profiling of purified metallic versus semiconducting SWCNTs has been pursued only in bacteria, with the conclusion that aggregated M-SWCNTs are more damaging to bacterial membranes than S-SWCNTs.

High-Concentration Aqueous Dispersions of Nanoscale 2D Materials Using Nonionic, Biocompatible Block Copolymers.

Conditions for the dispersion of molybdenum disulfide (MoS2) in aqueous solution at concentrations up to 0.12 mg mL(-1) using a range of nonionic, biocompatible block copolymers (i.e.

Fate and Transport of Molybdenum Disulfide Nanomaterials in Sand Columns.

Research and development of two-dimensional transition metal dichalcogenides (TMDC) (e.g., molybdenum disulfide [MoS]) in electronic, optical, and catalytic applications has been growing rapidly.

Polybetaine modification of PDMS microfluidic devices to resist thrombus formation in whole blood.

Assembled polydimethylsiloxane microfluidic devices were modified with a sulfobetaine polymer through continuous "tip-to-tip" modification, significantly reducing blood clotting and extending device patency under blood flow. This technology can be designed to enable the development of devices that can continuously work in whole blood, especially in an extracorporeal or in vivo environment.

Rapid, nondestructive estimation of surface polymer layer thickness using attenuated total reflection fourier transform infrared (ATR FT-IR) spectroscopy and synthetic spectra derived from optical principles.

We have developed a rapid, nondestructive analytical method that estimates the thickness of a surface polymer layer with high precision but unknown accuracy using a single attenuated total reflection Fourier transform infrared (ATR FT-IR) measurement. Because the method is rapid, nondestructive, and requires no sample preparation, it is ideal as a process analytical technique. Prior to implementation, the ATR FT-IR spectrum of the substrate layer pure component and the ATR FT-IR and real refractive index spectra of the surface layer pure component must be known.