2014 bailey, nano research

Functionalized, carbon nanotube material for the catalyticdegradation of organophosphate nerve agents

Mark M. Bailey1,† (), John M. Heddleston1, Jeffrey Davis2, Jessica L. Staymates2, and

Angela R. Hight Walker1 ()

1 National Institute of Standards and Technology (NIST), Semiconductor and Dimensional Metrology Division, Gaithersburg, MD, USA2 National Institute of Standards and Technology (NIST), Materials Measurement Science Division, Gaithersburg, MD, USA † Present Address: United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Center for Aerobiological Sciences,

Fort Detrick, MD, USA

Received: 14 February 2013

Revised: 20 November 2013

Accepted: 17 December 2013

© Tsinghua University Press

and Springer-Verlag Berlin

Heidelberg 2013

KEYWORDS

single-wall carbon

nanotube

functionalization,

catalytically-active

nanomaterial,

chemical warfare agent

ABSTRACT

Recent world events have emphasized the need to develop innovative, functional

materials that will safely neutralize chemical warfare (CW) agents in situ to

protect military personnel and civilians from dermal exposure. Here, we

demonstrate the efficacy of a novel, proof-of-concept design for a Cu-containing

catalyst, chemically bonded to a single-wall carbon nanotube (SWCNT) structural

support, to effectively degrade an organophosphate simulant. SWCNTs have

high tensile strength and are flexible and light-weight, which make them a

desirable structural component for unique, fabric-like materials. This study aims

to develop a self-decontaminating, carbon nanotube-derived material that can

ultimately be incorporated into a wearable fabric or protective material to minimize

dermal exposure to organophosphate nerve agents and to prevent accidental

exposure during decontamination procedures. Carboxylated SWCNTs were

functionalized with a polymer, which contained Cu-chelating bipyridine groups,

and their catalytic activity against an organophosphate simulant was measured

over time. The catalytically active, functionalized nanomaterial was characterized

using X-ray fluorescence and Raman spectroscopy. Assuming zeroth-order reaction

kinetics, the hydrolysis rate of the organophosphate simulant, as monitored

by UV–vis absorption in the presence of the catalytically active nanomaterial,

was 63 times faster than the uncatalyzed hydrolysis rate for a sample containing

only carboxylated SWCNTs or a control sample containing no added nanotube

materials.

Nano Research 2014, 7(3): 390–398

DOI 10.1007/s12274-014-0405-3

Address correspondence to A.R. Hight Walker, [email protected]; M. Bailey, [email protected]

www.theNanoResearch.com∣www.Springer.com/journal/12274 | Nano Research

391 Nano Res. 2014, 7(3): 390–398

1 Introduction

Recent world events in the Middle East have de-

monstrated the continued reality of chemical warfare

(CW) threats, specifically the threat of organophosphate-

based nerve agents, such as Sarin (GB), Tabun (GA),

and Soman (GD). During the Gulf War, military

personnel were exposed to nerve agents during the

destruction of the Khamisiyah Ammunition Storage

Facility [1]. In 1995, domestic terrorists released the

organophosphate nerve agent Sarin within a crowded

Tokyo subway, tragically killing 13 people and injuring

nearly a thousand others [2]. These incidents emphasize

the need to engineer advanced functional materials

that will safely neutralize organophosphate chemical

agents to protect military service members and civilians

from dermal exposure.

Organophosphate nerve agents act by irreversibly

binding the enzyme acetylcholine esterase (AChE)

via phosphorylation with the active site [3, 4]. This

enzyme is present in the blood and in the peripheral

and central nervous systems, and its function is to

catabolize the neurotransmitter acetylcholine (ACh).

When AChE is inhibited, excess ACh accumulates at

neuron synapses, and the victim presents symptoms

associated with exposure to organophosphate nerve

agents. Exposure to high doses can lead to symptoms

within minutes or hours. These can include miosis,

nausea, vomiting, hyperhidrosis, hypersalivation,

hyperlacrimation, fasciculation, diarrhea, anxiety,

tremor, and other symptoms indicative of cholinergic

overstimulation [4]. Death usually occurs through

severe depression of the central nervous system,

and by asphyxiation caused by sustained diaphragm

paralysis and increased bronchial secretions [5]. Severe

poisoning that does not result in death has been

reported to precipitate long-term physiological and

psychological effects, such as myocardial damage,

post-traumatic stress disorder (PTSD), and diminished

intellectual and motor capabilities [5].

Current physical protective measures deployed

against CW agents utilize gas masks and chemical-

resistant suits, boots, and gloves that protect the user

from exposure [6]. Chemical protective suits will

prevent dermal exposure to the chemical agent, but

if the CW threat is environmentally persistent (i.e.,

does not spontaneously degrade over short periods

of time), the personal protective equipment would

still require decontamination and disposal [7]. This

limitation could lead to accidental exposure, and

necessitates the development of novel materials that

will combine protective measures with in situ CW

agent degradation.

While detection of the agent is critical [8] studies

have also aimed to develop polymeric catalysts [2, 7,

9–10], metal oxide nanoparticle-containing materials

[11–13], organometallics [14], and enzyme-containing

materials [15–17] to accelerate the chemical degradation

of organophosphate nerve agents. Carbon nanotubes

have been used to develop sensors for the detection

of organophosphates [18–20], and carbon nanotube-

based materials have been designed for the degradation

of blistering agents [21]. Other types of non-carbon

nanotubes have also been explored for this purpose

[22]. However, single-wall carbon nanotubes (SWCNTs)

have unique mechanical properties and are very

light-weight, which make them a desirable structural

material for a variety of applications, including

threads and fabric-like materials with high tensile

strength [23–25]. Unlike multiwall carbon nanotubes

(MWCNT), SWCNTs offer a more homogenous sample

with protocols available for detailed, reproducible

characterization [26]. Chemical modification of carbon

nanotube threads and fabrics could lead to mul-

tifunctional materials that merge mechanical strength

with chemical functionality, such as catalytically

active materials that degrade CW agents in situ. This

study aims to develop a self-decontaminating, SWCNT-

derived material that can ultimately be incorporated

into a wearable fabric or protective material to

minimize dermal exposure to organophosphate nerve

agents and to prevent accidental exposure during

decontamination procedures.

2 Experimental

Certain commercial equipment, instruments, or materi-

als are identified in this article to specify adequately

the experimental procedure. Such identification does

not imply recommendation or endorsement by the

National Institute of Standards and Technology, nor

does it imply that the materials or equipment identified

| www.editorialmanager.com/nare/default.asp

392 Nano Res. 2014, 7(3): 390–398

are necessarily the best available for the purpose.

Carboxylated SWCNTs were purchased from Carbon

Solutions, Inc. (Riverside, CA). Polyallylamine HCl

was purchased from Sigma-Aldrich (St. Louis, MO).

2-2’-Bipyridine-4-carboxylic acid (BCA) was purchased

from Atlantic Research Chemicals Ltd (Cornwall,

United Kingdom). Spectra/Por cellulose ester dialysis

membrane (500 D to 1,000 D molecular weight cut-off)

was purchased from Spectrum Labs (Greensboro, NC).

Cellulose ester filter discs (0.05 μm pore size) were

purchased from EMD Millipore (Billerica, MA). All

other chemicals were purchased from Sigma-Aldrich

(St. Louis, MO). All materials were used as received

unless otherwise specified.

2.1 Polyallylamine-carboxylated bipyridine copoly-

mer synthesis (Scheme 1)

The copper-chelating copolymer 2-2’-bipyridine-4-

amido polyallylamine (with 70% of the amine groups

functionalized with bipyridine) was synthesized from

polyallylamine (Scheme 1(a)) and BCA (Scheme 1(b)).

First, 2-(N-morpholino)ethanesulfonic acid (MES)

buffer was made by dissolving MES in water (2 wt.%)

and adjusting the pH to 6.5 with aqueous sodium

hydroxide and hydrochloric acid solutions. Next,

250 mg of polyallyamine were dissolved in 1 mL of

MES buffer and stirred using a magnetic stir plate.

Approximately 345 mg of BCA were dissolved by

titrating with drops of 0.1 M NaOH. This solution

was then added to the polyallylamine solution

under stirring. Next, approximately 3 g of 1-ethyl-3-

(3-dimethylaminopropyl)carbodiimide (EDC) (10 molar

excess relative to 2-2’-bipyridine-4-carboxylic acid) were

dissolved in 1 mL of MES buffer, and approximately

3.2 g of N-hydroxysuccinimide (NHS) (1.5 molar

excess relative to BCA) were dissolved in 400 μL of

dimethyl sulfoxide (DMSO). The NHS solution was

added to the polyallylamine solution, after which the

EDC solution was added. Sufficient volume of MES

buffer was then added such that the final reaction

volume was 10 mL. The reaction was allowed to proceed

overnight under stirring and at ambient conditions.

The final product was then dialyzed against deionized

water and lyophilized.

2.2 Synthesis of catalytically active, functional

nanomaterial (Scheme 1)

The copper-chelating copolymer 2-2’-bipyridine-4-

Scheme 1 Reaction scheme of copolymer synthesis, conjugation to carboxylated SWCNTs via amidation, and catalyst formation. For all amidation reactions, EDC/NHS carbodiimide chemistry was used.


393 Nano Res. 2014, 7(3): 390–398

amino polyallylamine (Scheme 1C) was conjugated to

carboxylated SWCNTs (Scheme 1(d)) using EDC/NHS

carbodiimide chemistry. Typically, 6 mg of SWCNTs

and 60 mg of the copolymer were dissolved in 10 mL

of MES buffer. Next, approximately 14 mg of EDC were

dissolved in 2 mL of MES buffer, and approximately

3 mg of NHS were dissolved in 0.5 mL DMSO. The

NHS solution was first added to the carboxylated

SWCNTs/copolymer solution, then the EDC solution

was added under stirring. The reaction was allowed

to proceed overnight under stirring and at ambient

conditions. The final product (Scheme 1(e)) was then

dialyzed against deionized water and lyophilized.

For the Cu-containing catalyst (Scheme 1(f)),

approximately 50 mg of lyophilized SWCNT–

copolymer was first dissolved in 10 mL of deionized

water and 2 mL of 1 M aqueous CuCl2 and allowed to

stir overnight. Next, 1 mL of 1 M sodium hydroxide

solution was added and the suspension was allowed

to stir for several hours at room temperature. The

suspension was then vortexed and filtered through

a 0.05 μm cellulose ester filter and washed with

deionized water. The filtrate was then allowed to dry

overnight.

2.3 X-ray fluorescence (XRF) and Fourier transform

infra-red spectroscopy (FTIR)

XRF experiments were performed using an EDAX Eagle

III μXRF (Mahwah, NJ) containing a polychromatic

rhodium source filtered by an aluminum window.

For non-functionalized SWCNTs and carboxylated

SWCNTs, suspensions in acetone were drop cast onto

a SiO2/Si substrate and allowed to dry in a chemical

hood. Catalytically active, functional nanomaterial

was separated from the cellulose ester membrane and

placed on the SiO2/Si substrate. Spectral peaks were

assigned using NIST Desktop Spectrum Analyzer II

(DTSA-II) software [27]. The FTIR method is described

in the Electronic Supplementary Material (ESM,

Section 1).

2.4 Raman spectroscopy

Raman data were acquired on a Renishaw InVia

MicroRaman Spectrometer (Hoffman Estates, IL)

equipped with a 632.8 nm He–Ne laser, and a 514.5 nm

Ar+ laser. The measurements were calibrated against

the Si peak at 521 cm–1 prior to each measurement.

For sample preparation, carbon nanotube material

suspensions in acetone were drop cast onto a SiO2/Si

substrate. For the catalytically active, functional nano-

material, dried material was removed from the filter

and analyzed on the SiO2/Si substrate. Samples were

then illuminated using a 50× objective, which probes

approximately 2 m. Spectra were acquired and

analyzed using WiRE 33 software and Origin 8.6 at

multiple spots. A typical measurement used a 10 s

exposure time with three accumulations and a laser

power on the order of 50 μW for both the 633 nm and

514 nm band lines. The D and G band areas were

calculated by first normalizing the peak intensity to

G and then fitting the peaks with either a Gaussian

curve (D bands) or a Lorentzian curve (G bands) and

integrating. Combined standard uncertainties were

calculated using the root-sum-of-squares method.

2.5 Kinetic measurements

All kinetic studies were conducted using the chro-

mogenic organophosphate simulant, 4-nitrophenol

phosphate disodium salt, by measuring the UV–vis

absorbance of the evolved product, p-nitrophenol,

(Scheme 2) at 410 nm ± 10 nm wavelength [28].

A flask containing approximately 50 mg of hetero-

geneous catalyst on cellulose-ester membrane along

with the organophosphate simulant solution was stirred

at room temperature in parallel with an identical

apparatus containing simulant solution without any

material (“control”), or a sample containing only

carboxylated SWCNTs. For the SWCNT sample,

approximately 10 mg of carboxylated SWCNTs were

suspended in water and filtered onto a cellulose-ester

membrane. All reaction vessels were charged with

50 mL of 50 mM disodium phosphate solution in

deionized water and were sampled over time. For the

smaller-scale statistical experiments, 10 mL scintillation

vials containing 7 mL of 50 mM 4-nitrophenol phos-

phate disodium salt solution in deionized water

were charged with either 10 mg of catalytically active,

functional nanomaterial, or 2 mg of carboxylated

SWCNTs on cellulose ester-membrane, or no material

(“control”), with n = 3 for each treatment. For all

experiments, UV–vis spectra were acquired on a

Perkin Elmer Lambda 25 UV–vis spectrophotometer

(Waltham, MA) at several different time points over


394 Nano Res. 2014, 7(3): 390–398

40 hours, and were analyzed using Origin 8.6. Area

under the curve between 400 nm and 420 nm was

calculated using the trapezoid rule. Background

was subtracted, and absorbance measurements were

normalized to the baseline (time 0) measurement.

Statistical analysis was performed using a Students’

two-tailed t-test.

3 Results and discussion

A bipyridine-containing copolymer (Scheme 1) was

prepared from polyallylamine (Scheme 1(a)) and a

carboxylated bipyridine, 2,2’-bipyridine-4-carboxylaic

acid (Scheme 1(c)) using carbodiimide amidation

chemistry. Carboxylated SWCNTs (Scheme 1(d)) were

functionalized with the bipyridine-containing polymer

(Scheme 1(c)), forming a SWCNT–copolymer com-

posite (Scheme 1(e)). With the addition of copper(II)

chloride and sodium hydroxide to the SWCNT–

copolymer composite, the bipyridine groups form a

copper chelate, which is the catalytically active

site against organophosphates (“catalytically active,

functional nanomaterial” will refer to the SWCNT–

copolymer containing the chelated copper ions) [1].

The presence of carboxyl groups on the SWCNTs,

which ease functionalization, was confirmed using

FTIR (Fig. S1 in the ESM). These data corroborate the

manufacturer’s carboxylation claim, based on their solid

state NMR results (data not shown). The presence of

copper in the catalytically active, functional nano-

material was determined using X-ray fluorescence. In

Fig. 1, the spectra show strong CuK-family peaks in the

catalyst sample (Fig. 1(a)), confirming the presence of

copper. The as-received carboxylated SWCNTs were

also analyzed (Fig. 1(b)), and the spectrum showed

NiK-family peaks, which are most likely residual material

Scheme 2 Evolution of p-nitrophenol.

Figure 1 X-ray fluorescence (XRF) spectra of carboxylated SWCNTs (a), and the catalytically active, functional nanomaterial (b).


395 Nano Res. 2014, 7(3): 390–398

from the manufacturing process. The SiK-family peak is

from the substrate. The spectrum also showed small

AsK-family peaks, which are from a dopant in the Si

substrate. The catalytically active, functional nano-

material sample did not show any NiK-family peaks, thus

it is unlikely that the Ni would interfere with the results

of the kinetic study. The slight increase in intensity of

the background around 15 keV is due to Compton

scattering and scattering from the Rh source [29].

Raman spectra of carboxylated SWCNTs, and the

catalytically active, functional nanomaterial are shown

in Fig. 2. The spectra show radial breathing modes

(RBM) for all samples at excitation wavelengths of both

514 nm (Fig. 2(a)) and 633 nm (Fig. 2(b)), confirming the

presence of SWCNTs. The RBMs for the catalytically

active, functional nanomaterial at 514 nm excitation

are difficult to resolve, due to background photo-

luminescence of the polymer. RBM peaks are observed

with the carboxylated SWCNTs and the catalytically

active, functional nanomaterial at this excitation

wavelength. An increase in the intensity of the D peak

(reported as a decrease in the G/D ratio) is a measure

of defects, and increases at both excitation energies.

This is due to the introduction of defects in the carbon

nanotube lattice during carboxylation and further

functionalization, and corroborates the carboxylation

and functionalization of the SWCNTs. Homogeneity of

samples was accessed at three points in each sample,

which were found to be in good agreement, thus only

spectra from single measurements are reported. G/D

ratios from single measurements, with combined

standard uncertainties, are listed in Table 1.

Kinetic experiments were performed to evaluate the

catalytic activity of the catalytically active, functional

nanomaterial, based on Scheme 1. Figure 3 shows the

activity of the catalytically active, functional nano-

material against the organophosphate simulant,

4-nitrophenol phosphate disodium salt, in water.

Table 1 G/D ratios +/ combined standard uncertainty (UC)

Sample Excitation laser (nm) G/D ± UC

633 10.08 ± 0.232Carboxylated SWCNTs (as received) 514 27.20 ± 2.33

633 3.639 ± 0.157Catalytically active, functional nanomaterial 514 3.856 ± 0.130

The absorbance of the evolved hydrolysis product,

p-nitrophenol, was measured by calculating the area

under the curve from 400 nm to 420 nm, as described

previously [2]. Absorbance spectra from 400 nm to

550 nm are included in Fig. S2 (in the ESM). For

the uncatalyzed reaction (“control”), the absorbance

change of the organophosphate simulant without the

functional nanomaterial was measured over time. The

absorbance change of carboxylated SWCNTs without

the polymer/Cu functionalization, was also measured

over time. Assuming zeroth-order (linear) reaction

kinetics from 0 to 1,500 min, the relative reaction

rate of the catalyzed reaction is about 63 times faster

than the rates of both the control reaction and the

SWCNTs only reaction, both of which showed no

significant change in absorbance (Fig. 3(a)). In the

Figure 2 Raman spectra of samples using excitation at (a) 514 nm and (b) 633 nm for the as-received carboxylated SWCNTs, and the catalytically active, functional nanomaterial. G/D ratios are listed in Table 1.


396 Nano Res. 2014, 7(3): 390–398

second kinetic study, three reactors for each treatment

(catalyzed, control, and SWCNTs only) were sampled

at three different time points. At 16 hours, 24 hours, and

40 hours, the catalyzed samples showed a statistically

significant increase (p<0.01) in absorbance verses

the control sample and the SWCNT-only sample.

Additionally, the absorbance of the catalyzed sample

at 40 hours was significantly higher (p<0.05) than

the absorbance of the catalyzed sample at 16 hours,

showing an increase in absorbance over time. In a third

kinetic study, two reactors of control and catalytically

active nanomaterial were compared for their ability

to degrade the organophosphate substrate over an

extended observational period (Fig. S3, in the ESM).

After 18 days and 3 separate rounds of experiments,

the catalytic material maintained its function without

any discernible loss in catalysis of the substrate.

The proposed reaction mechanism is described in

Scheme S1 (in the ESM).

4 Conclusions

This study demonstrates the efficacy of a novel,

proof-of-concept design for a Cu-containing catalyst,

chemically bonded to a SWCNT support that shows

catalytic activity statistically better than carboxylated

SWCNTs and an uncatalyzed hydrolysis reaction

(“control”). The carbon nanotube matrix provides

structural support for the catalytic polymer, potentially

making it suitable for a variety of applications. We

also demonstrate that this novel material maintains

its catalytic function after repeated use for up to

several weeks of constant catalysis. Future work will

examine the possibility of functionalizing carbon

nanotube yarn with the copper-containing polymer

and weaving it into fabric for in situ chemical defense

applications.

Acknowledgements

The authors gratefully acknowledge funding from the

United States National Research Council Post-Doctoral

Research Associateship Program.

Electronic Supplementary Material: Supplementary

material, including FTIR data, proposed hydrolysis

reaction mechanism, and UV–vis absorption data,

is available in the online version of this article at

http://dx.doi.org/10.1007/s12274-014-0405-3.

References

[1] Persian Gulf War Illness Task Force. Khamisiyah: A Historical

Perspective on Related Intelligence [Online]. Persian Gulf

Figure 3 Kinetic measurements of the CW agent simulant hydrolysis. (a) The relative absorbance change of the hydrolysis product overtime in the presence of the catalytically active, functional nanomaterial (catalyzed), with carboxylated SWCNTs, and without anymaterial (control). (b) A comparison of the relative absorbance change at three different time points with n = 3 for each treatment.Uncertainty bars indicate standard deviation, and an * indicates a statistically significant difference with p<0.01 and ** indicates p<0.05.


397 Nano Res. 2014, 7(3): 390–398

War Illness Task Force; http://www.gulflink.osd.mil/cia_wp/

(accessed Aug 16, 2012).

[2] Russell, A. J.; Berberich, J. A.; Drevon, G. F.; Koepsel, R.

R. Biomaterials for mediation of chemical and biological

warfare agents. Annu. Rev. Biomed. Eng. 2003, 5, 1–27.

[3] Munro, N. B.; Watson, A. P.; Ambrose, K. R.; Griffin, G. D.

Treating exposure to chemical warfare agents: Implications

for health care providers and community emergency planning.

Environ. Health Perspect. 1990, 89, 205–215.

[4] Reutter, S. Hazards of chemical weapons release during

war: New perspectives. Environ. Health Perspect. 1999, 107,

985–990.

[5] Brown, M. A.; Brix, K. A. Review of health consequences

from high-, intermediate- and low-level exposure to

organophosphorus nerve agents. J. Appl. Toxicol. 1998, 18,

393–408.

[6] Army Medical Department Center and School. Multiservice

Tactics, Techniques, and Procedures for Treatment of Chemical

Agent Casualties and Conventional Military Chemical Injuries.

Departments of the Army, The Navy, and the Air Force and

the Commandant of the Marine Corps: Fort Sam Houston,

TX, 2007.

[7] Amitai, G.; Murata, H.; Andersen, J. D.; Koepsel, R. R.;

Russell, A. J. Decontamination of chemical and biological

warfare agents with a single multi-functional material.

Biomaterials 2010, 31, 4417–4425.

[8] Hight Walker, A. R.; Suenram, R. D.; Samuels, A.; Jensen, J.;

Ellzy, M. W.; Lochner, J. M.; Zeroka, D. Rotational spectrum

of Sarin. J. Mol. Spectrosc. 2001, 207, 77–82.

[9] Erdem, M.; Say, R.; Ersöz, A.; Denizli, A.; Türk, H.

Biomimicking, metal-chelating and surface-imprinted polymers

for the degradation of pesticides. React. Funct. Polym. 2010,

70, 238–243.

[10] Hartshorn, C. M.; Singh, A.; Chang, E. L. Metal-chelator

polymers as organophosphate hydrolysis catalysts. J. Mater.

Chem. 2002, 12, 602–605.

[11] Wagner, G. W.; Bartram, P. W.; Koper, O.; Klabunde, K. J.

Reactions of VX, GD, and HD with nanosize MgO. J. Phys.

Chem. B 1999, 103, 3225–3228.

[12] Wagner, G. W.; Koper, O. B.; Lucas, E.; Decker, S.;

Klabunde, K. J. Reactions of VX, GD, and HD with nanosize

CaO: Autocatalytic dehydrohalogenation of HD. J. Phys.

Chem. B 2000, 104, 5118–5123.

[13] Wagner, G. W.; Procell, L. R.; O’Connor, R. J.; Munavalli,

S.; Carnes, C. L.; Kapoor, P. N.; Klabunde, K. J. Reactions

of VX, GB, GD, and HD with nanosize Al2O3. Formation

of aluminophosphonates. J. Am. Chem. Soc. 2001, 123,

1636–1644.

[14] Badawi, A. M.; Hafiz, A. A.; Ibrahim, H. A. Catalytic

destruction of malathion by metallornicelle layers. J.

Surfactants Deterg. 2003, 6, 239–241.

[15] Gill, I.; Ballesteros, A. Degradation of organophosphorous

nerve agents by enzyme–polymer nanocomposites: Efficient

biocatalytic materials for personal protection and large-scale

detoxification. Biotechnol Bioeng 2000, 70, 400–410.

[16] Popiel, S.; Nawala, J.; Sankowska, M.; Witkiewicz, Z.;

Bernat, P. Enzymes as catalysts of decomposition of chemical

warfare agents. Przem. Chem. 2010, 89, 1361–1369.

[17] Yang, F. X.; Wild, J. R.; Russell, A. J. Nonaqueous biocatalytic

degradation of a nerve-gas mimic. Biotechnol. Prog. 1995,

11, 471–474.

[18] Sharma, S. P.; Tomar, L. N. S.; Acharya, J.; Chaturvedi, A.;

Suryanarayan, M. V. S.; Jain, R. Acetylcholinesterase

inhibition-based biosensor for amperometric detection of

Sarin using single-walled carbon nanotube-modified ferrule

graphite electrode. Sens. Actuaters B—Chem. 2012, 166,

616–623.

[19] Wei, Y.; Liu, Z. G.; Gao, C.; Wang, L.; Liu, J. H.; Huang,

X. J. Electrochemical sensors and biosensors based on

nanomaterials: A new approach for detection of organic

micropollutants. Prog. Chem. 2012, 24, 616–627.

[20] Zeng, Y.; Yu, D.; Yu, Y.; Zhou, T.; Shi, G. Differential pulse

voltammetric determination of methyl parathion based

on multiwalled carbon nanotubes-poly(acrylamide) nano-

composite film modified electrode. J. Hazard. Mater. 2012,

217, 315–322.

[21] Sharma, P. K.; Gupta, G.; Nigam, A. K.; Pandey, P.; Boopathi,

M.; Ganesan, K.; Singh, B. Photoelectrocatalytic degradation

of blistering agent sulfur mustard to non-blistering substances

using pPy/NiOBPC nanocomposite. J. Mol. Catal. A: Chem.

2013, 366, 368–374.

[22] Grandcolas, M.; Louvet, A.; Keller, N.; Keller, V. Layer-by-

layer deposited titanate-based nanotubes for solar photocatalytic

removal of chemical warfare agents from textiles. Angew.

Chem. Int . Edit. 2009, 48, 161–164.

[23] Ghemes, A.; Minami, Y.; Muramatsu, J.; Okada, M.; Mimura,

H.; Inoue, Y. Fabrication and mechanical properties of carbon

nanotube yarns spun from ultra-long multi-walled carbon

nanotube arrays. Carbon 2012, 50, 4579–4587.

[24] Miao, M. H. Production, structure and properties of twistless

carbon nanotube yarns with a high density sheath. Carbon

2012, 50, 4973–4983.


398 Nano Res. 2014, 7(3): 390–398

[25] Steiner, S.; Busato, S.; Ermanni, P. Mechanical properties and

morphology of papers prepared from single-walled carbon

nanotubes functionalized with aromatic amides. Carbon 2012,

50, 1713–1719.

[26] Decker, J. E.; Hight Walker, A. R.; Bosnick, K.; Clifford, C. A.;

Dai, L.; Fagan, J.; Hooker, S.; Jakubek, Z. J.; Kingston, C.;

Makar, J. et al. Sample preparation protocols for realization

of reproducible characterization of single-wall carbon

nanotubes. Metrologia 2009, 46, 682–692.

[27] Ritchie, N. DTSA-II [Online]. National Institute of Standards

and Technology (NIST); Retrieved from the Public Domain

Software from NIST: http://www.cstl.nist.gov/div837/837.02/

index.html (accessed Oct 24, 2012).

[28] Ramaseshan, R.; Sundarrajan, S.; Liu, Y. J.; Barhate, R. S.;

Lala, N. L.; Ramakrishna, S. Functionalized polymer nanofibre

membranes for protection from chemical warfare stimulants.

Nanotechnology 2006, 17, 2947–2953.

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