Mechanistic Investigations of Horseradish Peroxidase-Catalyzed Degradation of Single-Walled Carbon Nanotubes

详细信息    查看全文

• 作者：Brett L. Allen ; Gregg P. Kotchey ; Yanan Chen ; Naveena V. K. Yanamala ; Judith Klein-Seetharaman ; Valerian E. Kagan ; Alexander Star
• 刊名：Journal of the American Chemical Society
• 出版年：2009
• 出版时间：December 2, 2009
• 年：2009
• 卷：131
• 期：47
• 页码：17194-17205
• 全文大小：601K
• 年卷期：v.131,no.47(December 2, 2009)
• ISSN：1520-5126

文摘

Single-walled carbon nanotubes (SWNTs) have been investigated for a variety of applications including composite materials, electronics, and drug delivery. However, these applications may be compromised depending on the negative effects of SWNTs to living systems. While reports of toxicity induced by SWNTs vary, means to alleviate or quell these effects are in small abundance. We have reported recently the degradation of carboxylated SWNTs through enzymatic catalysis with horseradish peroxidase (HRP). In this full Article, we investigated the degradation of both carboxylated and pristine SWNTs with HRP and compared these results with chemical degradation by hemin and FeCl₃. The interaction between pristine and carboxylated SWNTs with HRP was further studied by computer modeling, and the products of the enzymatic degradation were identified. By examining these factors with both pristine and carboxylated SWNTs through a variety of techniques including atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman spectroscopy, ultraviolet−visible−near-infrared (UV−vis−NIR) spectroscopy, gas chromatography−mass spectrometry (GC−MS), high-performance liquid chromatography (HPLC), and liquid chromatography−mass spectrometry (LC−MS), degradation pathways were elucidated. It was observed that pristine SWNTs demonstrate no degradation with HRP incubation but display significant degradation when incubated with either hemin or FeCl₃. Such data signify a heterolytic cleavage of H₂O₂ with HRP as pristine nanotubes do not degrade, whereas Fenton catalysis results in the homolytic cleavage of H₂O₂ producing free radicals that oxidize pristine SWNTs. Product analysis shows complete degradation produces CO₂ gas. Conversely, incomplete degradation results in the formation of different oxidized aromatic hydrocarbons.