Nanotoxicology

Nanoparticles are now incorporated in more than 1000 commercial products including textiles, conductive inks, solar cells, personal care products, medical devices, cosmetics, appliances, and baby products ensuring that the general population will be in contact with nanomaterials on a frequent and long-term basis during their daily lives. While the benefits of nanomaterials have been recognized, there is concern that some nanotechnology enabled products may pose a risk to the environment and human health at some point in their life cycle. Some research suggests that nanomaterials are potentially more toxic than their bulk counterparts, so the new field of nanotoxicology has formed to both predict and measure the health impacts and environmental implicationsof nanomaterials.

Nanotox at nanoComposix

NanoComposix has been providing precisely engineered, highly purified, and extensively characterized nanoparticles to toxicology researchers for >5 years. Comprehensive specification sheets detailing thephysical and chemical information about the nanoparticles are providedwith each batch. Additionally, we provide information about how the nanoparticles are transformed when exposed to various environments. For example, it is importantto understand how the aggregation state and surface chemistry of nanoparticles changes when introduced into an in-vitro model system in order to interpret the data from the assay. NanoComposix is actively involved in the following areas that are of interest to nanotoxicology researchers:

BioPure Metal Nanoparticles

BioPure Silver and Gold nanoparticles are precisely sized, unagglomeratedspherical nanoparticles with a narrow size distribution. The particles are concentrated (1 mg/mL) and provided with a characterization sheet that contains information on the important physical and chemical properties of the nanoparticles. Additionally, each formulation is extensively washed so that the solution is free from residual reactants from the manufacturing process. This is important to ensure that theresponse measuredis due to the nanoparticles themselves and not a contaminant.

Effect of Shape on Toxicity

The shape of nanoparticles can affect the optical, thermal, and electronic properties of the material. It is important to understand how shape impacts adsorption, biodistribution, metabolism, and elimination.NanoComposix has developed fabrication methods to produce nanoparticles with various geometries including rods, wires, plates, cubes, and triangles. Of particular concern are high aspect ratiomaterials, such ascarbon nanotubes and asbestos, which may be difficult for the body to clear and have demonstratedtoxicity associated with their dimensions.

Surface Functionalization

Since the body interacts with the surface of nanomaterials first, the surface state of nanoparticles is one of the most important parameters for determining distribution and transport in the body. In order to test hypothesis regarding surface effects on mechanisms of action and to develop definitive risk models associated with surface, a method of identifying and exchanging chemical moieties on the surface of nanoparticles is highly desirable. A core technology at nanoComposix is the ability to functionalize the surface of nanoparticles with a variety of polymers, biomolecules, and other capping agents. Examples of common surface materials includes silica, PEG, PVP, citrate, phosphate, tannic acid, and biomolecules such as antibodies and DNA. Methods have been developed to both exchange and monitor the efficacy of the exchange. Tools utilized to understand changes to the surface of thenanoparticles include isoelectric point, matrix aided laser desorption ionization mass spectrometer (MALDI-MS), Fourier Transform Infrared Spectroscopy (FTIR), and Raman spectroscopy.

Panels of Materials Relevant for Release

Relevant hazard identification for nanoparticles requires an understanding of the applications and properties of materials that are currently on the market. NanoComposix has assembled representative sources of nanomaterials with great potential for environmental release due to its prevelent in the commercial and industrial market. Each nanoparticle sample is extensively characterized to provide much more information on the physicochemical properties of the material than is provided by the original manufacturer. The particles are batched and monitored with time to ensure that storage has not altered their properties. Materials of interest include various forms of carbon (C₆₀, nanotubes, graphite, etc.), other metals (copper, manganese, iron, palladium, etc.), metal oxides (TiO₂, Fe₂O₃, CeO₂, ZrO, etc.), ceramics, and semiconductor nanoparticles. In addition to acquiring and characterizing the nanomaterials, we also purify, size fractionate, and functionalize these materials to assist in the isolation of the component that is most responsible for observed toxicity. These materials can also be suspended in solutiondepending on a particulartesting protocol.

Drying and Dispersion Capabilities

For most nanomaterials, aerosolization and inhalationrepresents the primary exposure pathway. Aerosolization can occur during the original manufacturing of the nanomaterials but can also occur during the handling and processing of nanomaterials. For example, spray drying ofnanoparticles for coatings, production of powdered materials, and the preparation of nanocomposite materials could result in exposure to nanoparticles via inhalation. NanoComposix has developed methods to dry nanoparticle suspensions using methods that maximize the aerosolizability of the material. A custom aerosol chamber is equiped with pneumatic, venturi, and burst disk launch mechanisms that disseminate nanomaterials with different shear forces to create nanoparticle clouds with various densities, average sizes, and aggregation levels. Instrumentation contained within the chamber can, in real-time, characterize particle counts, size distributions of aerosolized particles and aggregates in the size regime of 5-15,000 nm, identify mass loadings, and measure the optical properties (absorption, scattering, and extinctionat wavelengths from400 nm to 20 microns). Using these techniques the potential exposure risk of handling different types of nanomaterials can be quantified.