美國匹茲堡大學一跨國研究團隊發現，人類含有一種酵素，可分解奈米碳管的結構，並可以修補人體暴露於這種微小分子導致的健康損害。
奈米碳管是以碳原子組成的管狀晶體，管壁就是一個原子厚。而奈米碳管比頭髮細 100,000 倍，但比鋼還要堅固。
奈米碳管可以用來強化塑膠、陶瓷、水泥，同時也是電和熱的良導體，還可作為靈敏的化學感應器。
但是奈米碳管表面的上千個原子，會和人體進行目前未知的反應，研究發現，老鼠在奈米碳管吸入實驗中，感染了嚴重的肺炎和肺纖維化併發症。
匹茲堡研究團隊在自然奈米科技期刊(Nature Nanotechnology)的研究發表指出，他們的發現像開了一扇門，使奈米碳管可以用來作為安全的藥物輸送工具，並且還可發展出對人體自然的療法，幫助在環境或工作場合因奈米碳管而健康受損的人。
科學家發現，人體酵素 myeloperoxidase (hMPO) 生化分解後的奈米碳管，不會引發原本奈米碳管會造成的肺炎。
他們還發現，含有 myeloperoxidase (hMPO)的白血球，原本目的是殺死入侵的微生物，但可以被導向只攻擊奈米碳管。
「從hMPO生化分解奈米碳管的現象，可以說明自然的免疫反應中也包含分解外來物。」研究主持人匹茲堡大學公共衛生學院環安系副系主任卡根(Valerian Kagan)教授說：「下一步就是要發展出誘發此免疫反應的方法，並且在活體中複製相同的反應。」
科學家最近將研究重心放在human MPO的作用，因為hMPO作用時釋放的強酸和氧化劑，成份類似可分解奈米碳管的化學物質。
他們先在hMPO和過氧化氫的溶劑裡培養短的單壁奈米碳管，24小時後，大部分的奈米碳管結構都被完全破壞。
如果在溶劑裡加入氯化鈉，即食鹽，奈米碳管甚至會分解的更快。
接著在確認hMPO可以有效分解奈米碳管後，科學家捕捉白血球去接觸hMPO，藉此激發白血球攻擊奈米碳管。
他們將一種叫做 immunoglobulin G (IgG)的抗體植入奈米碳管裡，使奈米碳管成為白血球的特殊標的。
12小時後，含有IgG的奈米碳管100%被分解，而沒有IgG的奈米碳管只有30%被分解。
接下來他們實驗發現，肺組織若接觸已被分解的奈米碳管，7天後和健康的肺組織相比較，依然沒有太大差別，但如果肺組織接觸沒有被分解的奈米碳管，則會有嚴重的發炎現象。
A human enzyme that can biodegrade carbon nanotubes and offset the damaging health effects of being exposed to these tiny components has been identified by an international team of researchers based at the University of Pittsburgh.
Carbon nanotubes are one-atom thick rolls of graphite 100,000 times smaller than a human hair yet stronger than steel.
They are used to reinforce plastics, ceramics or concrete; they are excellent conductors of electricity and heat and also are sensitive chemical sensors.
But a nanotube's surface contains thousands of atoms that could react with the human body in unknown ways. Tests on mice have shown that nanotube inhalation results in severe lung inflammation coupled with scarring of the lungs known as fibrosis.
The research team reported today in the journal "Nature Nanotechnology" that their results could open the door to the use of carbon nanotubes as a safe drug-delivery tool. Their findings also could lead to the development of a natural treatment for people exposed to nanotubes, either in the environment or the workplace.
The researchers found that carbon nanotubes degraded with the human enzyme myeloperoxidase (hMPO) did not produce the lung inflammation that intact nanotubes have been shown to cause.
They also found that the white blood cells which contain and emit hMPO to kill invading microorganisms can be directed to attack only carbon nanotubes.
"The ability of hMPO to biodegrade carbon nanotubes reveals that this breakdown is part of a natural inflammatory response," said lead researcher Valerian Kagan, a professor and vice chair in the Department of Environmental and Occupational Health in Pitt's Graduate School of Public Health.
"The next step is to develop methods for stimulating that inflammatory response and reproducing the biodegradation process inside a living organism."
For the current study, the researchers focused on human MPO because it works by releasing strong acids and oxidants similar to the chemicals used to break down carbon nanotubes.
They first incubated short, single-walled nanotubes in an hMPO and hydrogen peroxide solution for 24 hours, after which the structure and bulk of the nanotubes had completely degenerated.
The nanotubes degenerated even faster when common table salt, sodium chloride, was added to the solution.
After establishing the effectiveness of hMPO in degrading carbon nanotubes, the team developed a technique to prompt the white blood cells to attack nanotubes by capturing them and exposing them to the enzyme.
They implanted a sample of nanotubes with antibodies known as immunoglobulin G (IgG), which made them specific targets for the white blood cells.
After 12 hours, 100 percent of the IgG nanotubes were degraded versus 30 percent of those without IgG.
In subsequent laboratory tests, lung tissue exposed to the degraded nanotubes for seven days showed little change when compared to unexposed lung tissue. But lung tissue exposed to untreated nanotubes developed severe inflammation.
Additional Pitt researchers included Yulia Tyurina, a Pitt assistant professor of environmental and occupational health in the Graduate School of Public Health, and Donna Stolz, an associate professor of cell biology and physiology in Pitt's medical school.
Other participating researchers are from Sweden's Karolinska Institute, Trinity College in Ireland, West Virginia University and the National Institute for Occupational Safety and Health.
Copyright Environment News Service (ENS) 2010. All rights reserved.
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In my healing journey and learning to attain the breath awareness, I become aware of the reality that all the creatures of the world are breathing the same breath. Take action, here and now. From my physical being to the every corner of this out of balance's planet.
