Thursday, July 29, 2010

Horseradish Enzyme Used To Degrade Carbon Nanomaterials

A method of degrading carbon nanomaterials includes mixing the carbon nanomaterials with a composition comprising a peroxide substrate and at least one catalyst selected from the group of an enzyme and an enzyme analog. The peroxide substrate undergoes a reaction in the presence of the catalyst to produce an agent interactive with the nanotubes to degrade the carbon nanomaterials. The peroxide substrate can, for example, be hydrogen peroxide or an organic peroxide.   The enzyme is horseradish peroxidase or a myeloperoxidase. 

Inventors Alexander Star, Valerian E. Kagan and Brett Lee Allen (Pittsburgh, Pa) in U.S. Patent Application 20100190239 detail a method of degrading carbon nanomaterials includes mixing the carbon nanomaterials with a composition comprising a peroxide substrate and at least one catalyst selected from the group of an enzyme and an enzyme analog. The peroxide substrate undergoes a reaction in the presence of the catalyst to produce an agent interactive with the nanotubes to degrade the nanomaterials. The peroxide substrate can, for example, be hydrogen peroxide (H2O2 or HOOH) or an organic peroxide (ROOR', wherein R is generally any organic substituent or group and R' is generally any organic substituent or group or R' is H). In general, the agent is oxidative. The composition can, for example, be added to a system (for example, an environment or an organism/living tissue) including the carbon nanomaterials. 

In the past few years, the scientific world has made vast strides in developing applications for carbon nanomaterials (for example, nanotubes). Following suit, manufacturers and commercial plants have increased production of carbon nanotubes and other carbon nanomaterials to meet the increasing demand.

Carbon nanomaterials such as carbon nanotubes have, however, exhibited toxic effects, resulting in an increased risk in handling and use of these materials. Single-walled carbon nanotubes(SWNTs or SWCNTs) have, for example, been at the forefront of nanoscience research for a variety of applications including gas sensing, composite materials, biosensing, and drug delivery. While the latter two applications have been successful, there are reports of cellular toxicity induced by SWNTs. Specifically, oxidative stress and the formation of free radicals, robust inflammatory response, and even asbestos-like pathogenicity have been found as a result of the introduction of SWNTs into biological systems.

As carbon nanomaterial production increases, the risk of environmental contamination is increasing. Such contamination can subsequently diffuse through aquifers and residential drinking water. As a result, precautions will have to be taken to ensure that the public, as well as the manufacturers, are safe from the toxic effects associated with these materials.

While oxidative "cutting" of carbon nanotubes and other carbon nanomaterials by aggressive and toxic oxidizing reagents is commonly used in laboratory practice, such oxidative reagents are not generally suitable for use in the environment outside the laboratory or in vivo. Carbon nanotubes can also be destroyed or degraded by incineration. However, incineration requires the ability to locate, collect, and/or concentrate carbon nanotube samples from the environment, which is often very difficult or even impossible

Unlike the known oxidative cutting of carbon nanotubes by aggressive and toxic oxidizing reagents, catalyst initiated degradation utilizes components which are substantially non-toxic and do not require aggressive reagents.

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