Multifunctional and Recollectable Carbon Nanotube Ponytails for Water Purification

Carbon nanotubes (CNTs) are promising nanomaterials that have the potential to revolutionize water treatment practices in the future. The direct use of unbounded CNTs, however, poses health risks to humans and ecosystems because they are difficult to separate from treated water. Here, we report the design and synthesis of carbon nanotube ponytails (CNPs) by integrating CNTs into micrometer-sized colloidal particles, which greatly improves the effectiveness of post-treatment separation using gravitational sedimentation, magnetic attraction, and membrane filtration. We further demonstrate that CNPs can effectively perform major treatment tasks including adsorption, disinfection, and catalysis. Using model pollutants such as methylene blue, <i>Escherichia coli</i>, and <i>p</i>-nitrophenol, we show that all the surfaces of individual CNTs in CNPs are accessible during water treatment. Our results suggest that the rational design of hierarchical structures represents a feasible approach to develop nanomaterials for engineering applications such as water and wastewater treatment

Sequence identity distribution.

<p>All BLASTX-hit transcripts were calculated. Vertical histogram shows the number of transcripts with which the range of percentage hit by BLASTX.</p

Statistics of <i>de novo</i> assembly output of sweet potato transcriptome.

<p>E75, E70, E65, E60, E55 and E50 were assembled by Edena; V75, V70, V65, V60, V55 and V50 by Velvet; S75, S70, S65, S60, S55 and S50 by SOAPdenovo. CC is contigs provided by the commercial assembler service, and FA is the final assembly with CAP3.</p

Comparison of the sensitivity and accuracy of <i>de novo</i> transcriptome assemblies.

<p>Sensitivity (triangle) and accuracy (cross) were calculated based on the result of blast (See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036234#s4" target="_blank">Materials and Methods</a> for detail) under the condition of HSPs length ≥50 bp, identity ≥90% and E-value<1e⁻¹⁰. The histogram represents the average value of sensitivity and accuracy. E75, E70, E65, E60, E55 and E50 were assembled by Edena; V75, V70, V65, V60, V55 and V50 by Velvet; S75, S70, S65, S60, S55 and S50 by SOAPdenovo. CC, SC and UC are contigs, scaffolds and unigenes provided by the commercial assembler service, respectively. FA is the final assembly, and SPGI is the newly published Sweet Potato Gene Index by CIP (International Potato Center).</p

Transcripts specifically expressed between different tissues.

<p>Specifically expressed transcripts were quantified. The numbers of DGE transcripts of 21 comparisons between each two samples are shown in blue and red histograms (top vs. bottom).</p

Top-Hit species distribution.

<p>51,763 BLASTX-hit transcripts were calculated. Species with proportions of more than 1% are shown. More than 70% of the identified transcripts have the highest homology with <i>Vitis</i>, <i>Populus</i> or <i>Ricinus</i>. Less than 5% of the top matches hit sweet potato itself due to the limited number of the sweet potato protein sequences available in the NCBI database.</p

Transcripts differentially expressed between different tissues.

<p>Up-(red) and down-regulated (green) transcripts were quantified. The results of 21 comparisons between each two samples are shown.</p

Summary of ORF prediction.

<p>E75, E70, E65, E60, E55 and E50 were assembled by Edena; V75, V70, V65, V60, V55 and V50 by Velvet; S75, S70, S65, S60, S55 and S50 by SOAPdenovo. CC, UC are contigs and unigenes provided by the commercial assembler service. FA is the final assembly with CAP3, and SPGI is the newly published Sweet Potato Gene Index by CIP (International Potato Center).</p

Histogram representation of GO classification.

<p>Transcripts were annotated in three categories: cellular components, molecular function and biological processes.</p

Statistics of DGE library sequencing and tag mapping.

*<p>: Percent of Clean Tag; UCT: Unambiguous Clean Tags; UDCT: Unambiguous Distinct Clean Tags; YL: Young leaves; ML: Mature leaves; Stem: Stems; FR: Fibrous roots; ITR: initial tuberous roots; ETR: expanding tuberous roots; HTR: harvest tuberous roots.</p