Colloids and Surfaces A: Physicochem. Eng. Aspects 395 (2012) 207–216
Contents lists available at SciVerse ScienceDirect
Colloids and Surfaces A: Physicochemical and
Engineering Aspects
jo ur nal homep a ge: www.elsevier.com/locate/colsurfa
Highly stable and redox active nano copper species stabilized
functionalized-multiwalled carbon nanotube/chitosan modified electrode for
efficient hydrogen peroxide detection
Senthil Kumar Annamalai
a,∗
, Barathi Palani
a
, K. Chandrasekara Pillai
b
a
Environmental and Analytical Chemistry Division, School of Advanced Sciences, Vellore Institute of Technology University, Vellore 632 014, India
b
Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan
a r t i c l e i n f o
Article history:
Received 1 July 2011
Received in revised form
13 November 2011
Accepted 7 December 2011
Available online 16 December 2011
Keywords:
Nano copper species
Functionalized carbon nanotube
Chitosan
Hydrogen peroxide
Milk sample analysis
a b s t r a c t
A highly redox active and stable nano copper species immobilized functionalized-multiwalled carbon
nanotube (f-MWCNT) + chitosan (CHIT) film coated glassy carbon electrode (Cu@f-MWCNT + CHIT/GCE)
was fabricated using a new preparation procedure, different from the conventional Cu
2+
+ MWCNT + CHIT
bulk electro-codeposition coupled glassy carbon surface activation method, for selective and sensitive
amperometric estimation of H
2
O
2
at -100 mV vs Ag/AgCl in physiological solution. Several copper
modified film electrodes with nano copper species immobilized into films made of single compo-
nent or different combinations of CNT and CHIT (i.e., Cu@f-MWCNT + CHIT/GCE, Cu@SWCNT + CHIT/GCE,
Cu@f-MWCNT/GCE, Cu@MWCNT/GCE, Cu@CHIT/GCE and Cu/GCE) were characterized by cyclic voltam-
metry in a blank pH 7 phosphate buffer solution (PBS), and only the Cu@f-MWCNT + CHIT/GCE showed
well-defined redox peak with an half-wave potential (E
1/2
) of -85 mV vs Ag/AgCl for the matrix
immobilized Cu
2+
/Cu
+
redox species with very good film stability and pronounced leaching resis-
tance to copper. Transmission electron microscopy, scanning electron microscopy, energy dispersive
X-ray analysis, X-ray photoelectron spectroscopy were used to give a complete characterization of the
Cu@f-MWCNT + CHIT/GCE. Effect of potential scan rate and pH on the redox response of the Cu@f-
MWCNT + CHIT/GCE was studied to probe the mechanism of Cu
2+
/Cu
+
electron transfer process. The
Cu@f-MWCNT + CHIT/GC electrode showed effective electrocatalytic reduction of H
2
O
2
in pH 7 PBS.
Amperometric i–t method of H
2
O
2
detection yielded a calibration plot linear up to 125 M with a cur-
rent sensitivity of 0.463 A M
-1
cm
-2
. The newly developed Cu@f-MWCNT + CHIT/GC electrode displayed
remarkable tolerance to co-existing interferents, such as cysteine, ascorbic acid, uric acid and nitrite at
the H
2
O
2
detection potential in pH 7 PBS. The ability of the sensor electrode for routine analyses was
demonstrated by the detection of H
2
O
2
present in simulated milk samples with appreciable recovery
values.
© 2011 Elsevier B.V. All rights reserved.
1. Introduction
Selective and sensitive detection of H
2
O
2
at physiological pH
without interference from common biochemicals, such as ascor-
bic acid (AA), uric acid (UA), nitrite (NO
2
-
) and cysteine (CySH)
is of challenging interest in food, biological and clinical applica-
tions. For instance, H
2
O
2
is commonly used as a food preservative
in milk and cheeses [1] and as a sterilant for packaging materials
[2] due to its inherent sporicidal and antibactericidal properties.
The Food and Drug Administration (FDA) recommends H
2
O
2
as
a “substance generally recognized as safe (GRAS)” reagent for
food with the recommended concentration limit value of 80 ppm
∗
Corresponding author. Tel.: +91 416 2202754.
E-mail address: askumarchem@yahoo.com (S.K. Annamalai).
[3]. Since the H
2
O
2
is an aggressive oxidizer that can corrode
many materials and damage human skin, its higher concentra-
tions (≥20%) are considered to be highly hazardous. Hence, simple,
selective and rapid monitoring technique for the H
2
O
2
is of signifi-
cant interest in various food processing industries. Electrochemical
sensor is an efficient tool for the H
2
O
2
detection [4]. In general,
for the selective H
2
O
2
electrochemical detection, several enzyme-
based electrochemical biosensors were developed, with enzymes,
such as horseradish peroxidase (HRP) [5,6], cytochrome c [7] and
hemoglobin [8], as an active site. Unfortunately, the enzyme-based
detection methodologies are often complicated, expensive, and
time consuming. Moreover, several precautions should be taken
to overcome the enzyme’s instability and temperature effects [9].
On the other hand, enzyme-free sensing systems are attractive,
if they can be able to detect the H
2
O
2
selectively at physiologi-
cal pHs. Here in, we are reporting an enzyme-free amperometric
0927-7757/$ – see front matter © 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.colsurfa.2011.12.032