In this communication, we have demonstrated that SiO(2) nanoparticles can be generated by simply scratching the quartz or silicon wafer with a SiO(2) layer and confirmed it to be active for the growth of SWNTs for the first time. Furthermore, the SWNTs from SiO(2) has a much narrower size distribution. This may open a way to control the diameter of the SWNTs. More importantly, our work has found a series of oxides including Al(2)O(3), TiO(2), and rare earth oxides to be active for SWNT growth as well. These findings not only provide an alternative new type of catalysts for the growth of SWNTs but also give more insight into the role of the catalysts and a deeper understanding of the growth mechanism of SWNTs. The effective catalysts and catalytic activity for SWNT growth seem to be more size-dependent than the catalysts. Long oriented SWNTs generated from these catalysts enable us to rule out the relationship between the catalysts and the structures of the SWNTs. Thus controlled growth of SWNTs including the diameter and chirality is expected to be eventually realized.

BackgroundBiomarkers that predict clinical response, tumor recurrence or patient survival are severely lacking for most cancers, particularly for oral and pharyngeal cancer. This study examines whether gene-promoter methylation of tumor DNA correlates with survival and recurrence rates in a population of patients with oral or pharyngeal cancer.MethodsThe promoter methylation status of the DNA repair gene MGMT and the tumor suppressor genes CDKN2A and RASSF1 were evaluated by methylation-specific PCR in 88 primary oral and pharyngeal tumors and correlated with survival and tumor recurrence. Quantitative MGMT methylation was also assessed.Results29.6% of the tumors presented with MGMT methylation, 11.5% with CDKN2A methylation and 12.1% with RASSF1 methylation. MGMT promoter methylation was significantly associated with poorer overall and disease-free survival. No differences in methylation status of MGMT and RASSF1 with HPV infection, smoking or drinking habits were observed. A significant inverse trend with the amount of MGMT methylation and overall and disease-free survival was observed (ptrend = 0.002 and 0.001 respectively).ConclusionThese results implicate MGMT promoter methylation as a possible biomarker for oral and pharyngeal cancer prognosis. The critical role of MGMT in DNA repair suggests that defective DNA repair may be correlative in the observed association between MGMT promoter methylation and tumor recurrence. Follow-up studies should include further quantitative MSP-PCR measurement, global methylation profiling and detailed analysis of downstream DNA repair genes regulated by promoter methylation.

In this Communication, we have demonstrated a facile and effective approach to identify the structure of the superlong well-aligned single-walled carbon nanotubes (SWNTs) by the combination of electrodeposition of metal (Ag) with Raman spectroscopy. The suitable density and the visibility of the Ag-deposited long oriented nanotubes make it possible to acquire Raman spectra from isolated individual nanotubes very easily. The results reveal that the well-oriented SWNT arrays on SiO2/Si wafer fabricated by EtOH chemical vapor deposition using Fe/Mo nanoparticles as catalyst exhibit a low percentage of metallic SWNTs (5%). Among other SWNTs about 62.3% are semiconducting SWNTs, and a small amount of nanotubes are quasimetallic. About 32% are a so-called quasi-insulator, which is caused inevitably by the defects during growth. Furthermore, the structural uniformity of the long SWNTs can be also evaluated by the deposition of Ag along the length and Raman spectroscopy. This method also provides an approach to deposit other metals on long SWNTs, which could have various potential applications such as for use as sensors, etc. More importantly, this facile method can be applied to long SWNT arrays fabricated from other different catalytic systems so that the relationship between the growth conditions and the structures of SWNTs are expected to be ruled out.

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