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Copyright © 2012 American Scientific PublishersAll rights reservedPrinted in the United States of America

Journal ofNanoscience and Nanotechnology

Vol. 12, 4119–4126, 2012

Nanoscale Biofilm Modification-Method Concerning a

Myoglobin/11-MUA Bilayers for Bioelectronic Device

Taek Lee1, Yong-Ho Chung1, Qi Chen1, Waleed Ahmed El-Said2,Junhong Min3�∗, and Jeong-Woo Choi1�2�∗

1Department of Chemical and Biomolecular Engineering, Sogang University, 35 Baekbeom-Ro (Sinsu-Dong),Mapo-Gu, Seoul, 121-742, Republic of Korea

2Interdisciplinary Program of Integrated Biotechnology, Sogang University, 35 Baekbeom-Ro (Sinsu-Dong),Mapo-Gu, Seoul, 121-742, Republic of Korea

3School of Integrated Engineering, Chung-Ang University, Heukseok-dong,Dongjak-Gu, Seoul 156-756, Republic of Korea

We developed surface modification tools for the fabrication of a bioelectronic device which consistsof a myoglobin monolayer self-assembled on an 11-MUA layer. To utilize a single protein as theactive element, it was necessary to reduce protein aggregation on the protein layer in the nanobioelectronic device, which was developed in our previous study and shown to display basic biomem-ory functions. Here, the reduction of myoglobin aggregation was accomplished by using 3-(3-cholamidopropyl) dimethylammonio-1-propanesulfonate (CHAPS) to fabricate a well-defined proteinlayer on the bioelectronic device. We investigated two different surface modification methods formaking well oriented biofilm. The effects of CHAPS on the formation of a myoglobin layer self-assembled on an 11-MUA layer were examined by atomic force microscopy and Raman spec-troscopy. The size of the myoglobin aggregates was reduced from 200∼250 nm to 10∼40 nmdepending on treatment method. The sustaining redox property of the CHAPS treated myoglobinlayer was examined using cyclic voltammetry. Using these techniques, we found that after sur-factant CHAPS treatment, protein aggregation was dramatically reduced and the protein layer stillmaintained its inherent electrochemical properties.

Keywords: Myoglobin, Bioelectronic Device, CHAPS, Atomic Force Microscopy, CyclicVoltammetry.

1. INTRODUCTION

Recently, the semiconductor industry has been confronted

with serious economical and technological problems. Par-

ticularly, it has been technologically difficult to produce a

line width that is under the 50 nm regime and semicon-

ductor products have generally been of low yield. Also,

the fabricating and manufacturing costs have increased in

direct proportion to the technological degree of difficulty

when the current ‘top-down’ method is used.

These problems have hampered the development of new

advanced semiconductor devices by the semiconductor

industry.1–4

There have been intensive efforts by several scientists

and engineers to resolve these problems. As a result,

a molecular electronic device has been suggested as

∗Author to whom correspondence should be addressed.

a potential powerful alternative solution to the current

problems facing the semiconductor industry. Molecular

electronics are based on a different type of technology

than what is currently being used by the semiconductor

industry. The ‘bottom-up’ method to fabricate functional

structures with molecules can be potentially used to fab-

ricate nano electronic devices that are under the 100 nm

regime. Using this concept, many molecular electronic

devices on the nanoscale have been devised and applied as

electronic devices, such as the sensor, diode and the other

electronic devices consisting of various chemical and bio

materials.5–9

We have previously proposed a shift register memory

composed of a Langmuir–Blodgett (LB) film to fabri-

cate a molecular scale diode, biomolecule-based recti-

fier for photocurrent generation. Recently, a molecular

electronic device based on biomolecule was suggested.

By using a biomolecule–based bioelectronic device, the

J. Nanosci. Nanotechnol. 2012, Vol. 12, No. 5 1533-4880/2012/12/4119/008 doi:10.1166/jnn.2012.5904 4119

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Nanoscale Biofilm Modification-Method Concerning a Myoglobin/11-MUA Bilayers for Bioelectronic Device Lee et al.

Fig. 1. Schematic diagram of (a) the myoglobin mixed with CHAPS solution, and then immobilized. (b) the effects of CHAPS treatment on the

myoglobin layer self-assembled on the gold substrate via an 11-MUA layer.

charge (information) could be stored in and read out using

an external potential that one can control.10–15 However,

this biomemory device has faced some problems regard-

ing biomolecule control, which needs to be resolved

before this concept can be used for the development of

a nano-scaled bioelectronic device. When metalloproteins

are immobilized on Au surface, they tend to aggregate

with each other. As a result, the proteins in the protein-

immobilized layer are not well orientated on the surface.

In this study, surfactant treatment was used with the aim

of creating a well oriented metalloprotein layer.

Myoglobin is a 17.3 kDa protein that consists of 153

amino acids. Myoglobin has one heme prosthetic group

containing an iron ion. This iron ion is responsible for

electron transfer by switching from a ferrous state to a

ferric state or rather switching from an oxidation state

to a reduction state. This redox property is easily and

efficiently utilized for the transfer of materials such as

oxygen in biological systems. When the two different

forms of myoglobin are switched on a substrate using an

external potential, the change in the redox state can be

easily monitored using reliable tools. These simple electro-

chemical properties of myoglobin can thus be exploited for

the development of a bioelectronic device that has mem-

ory functions. In the present study, a 3-[(3-cholamido-

propyl)dimethylammonio]-1-propanesulfonate (CHAPS)

was used to control the surface orientation for additional

treatment to make the well-ordered bioelectronic device.

As a surfactant, CHAPS was well known for segregating

the protein clusters and this surfactant used for control the

micellization and adsorption the protein aggregates.16�17

Therefore, the purpose of this study was, first, to form a

well defined myoglobin layer, which does not contain large

aggregates. Second, to retain its redox property which dis-

play well when treated by CHAPS. Here, we are trying

to find out an optimal surface modification method to

apply the molecular electronic device which contains the

biomolecules. We investigated the two different surface

modification methods.

Successful immobilization of myoglobin on the Au sub-

strate via 11-MUA layer and CHAPS were confirmed

by surface resonance spectroscopy (SPR) and atomic

force microscopy (AFM). Also, a Raman spectroscopy

was carried out for confirming the surface composi-

tions. The redox property of the myoglobin layer with

CHAPS treatment was assessed by cyclic voltammetry

(CV). A schematic diagram shows the CHAPS treatment

which was used to physically reduce protein aggregation.

Figure 1(a) shows the myoglobin mixed with CHAPS

solution, and then immobilized on 11-MUA modified Au

substrate. Figure 1(b) describes the effects of CHAPS

treatment on the myoglobin layer self-assembled on the

gold substrate via an 11-MUA layer.

2. EXPERIMENTAL DETAILS

2.1. Materials

Au substrates prepared by e-beam evaporation of 400 nm

of gold onto the clean and polished (100) plane of

a p-type silicon single crystal wafer primed with an

adhesion layer of about 10 nm of Cr, were pur-

chased from G-mek (Korea). A Pt Counter electrode

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Lee et al. Nanoscale Biofilm Modification-Method Concerning a Myoglobin/11-MUA Bilayers for Bioelectronic Device

and Ag/AgCl reference electrode were purchased from

BAS (USA) and use in the electrochemical experiments.

11-Mercaptoundecanoic Acid (11-MUA) and myoglobin

from horse heart were purchased from Sigma Aldrich Co

(USA). A 0.1 mg/ml myoglobin solution was prepared

in 10 mM 4-(2-hydroxyethyl)-1-piperazineethanesulfonic

acid (HEPES) buffer at pH 7.0. 3-[(3-cholamidopropyl)

dimethylammonio]-1-propanesulfonate (CHAPS) was pur-

chased from Fluka (Japan) and dissolved in 10 mM HEPES

solution. HEPES solution was used as the electrolyte

buffer.18

2.2. Fabrication of Myoglobin LayerSelf-Assembled on 11-MUA Layer

Au substrates were cleaned by immersing into piranha

solution with a 3:1 (v/v) mixture of sulfuric acid and

hydrogen peroxide for 5 min at 65 �C to remove organic

residues and dusts on the surface. The substrates were

then rinsed with deionized water and dried under a stream

of N2 gas. After washing, the surface of the substrates

were modified with 11-MUA. 150 mM 11-MUA solution

was dissolved in 5:5 (v/v) ethanol and glycerol. The sub-

strate was dipped into the 11-MUA solution for twelve

hours. During this incubation period, the thiol groups on

the 11-MUA molecules were covalently attached to the

Au molecules on the Au surface. The carboxyl groups on

the terminal ends of the 11-MUA molecules were used to

bind to the external amine groups of myoglobin through

electrostatic interactions. After this step, the modified sub-

strate was rinsed with ethanol and DI water to eliminate

excess alkanethiols that bound to the surface through phys-

ical adsorption. Finally, the 11-MUA modified Au surface

was immersed in 0.1 mg/ml myoglobin solution dissolved

in the 10 mm HEPES buffer solution for 6 hrs.19

2.3. Segregation of Myoglobin Aggregates bySurfactant CHAPS

The two methods were carried out to determine the optimal

treatment method. At first treatment method, the mixed

solution was shaked with a shaker set at 200 rpm for

24 hrs at 4 �C. And then, the mixed myoglobin was

purified 3000 MWCO Amicon filter (Millipore, USA) for

eliminating the excess CHAPS molecules. And then, the

mixed myoglobin solution was dropped onto the 11-MUA-

modified Au surface for self-assembly processing. After

this step, the surfactant-modified substrate was washed

with DI water. The surface-modified substrates were dried

under a stream of N2 gas.

Second treatment method, the myoglobin of 0.1 mg/ml

solution was diluted in 10 mM CHAPS solution for iso-

lating the aggregation. The prepared Au substrates were

immersed in a 10 mM CHAPS solution to stir the treated

solution. The substrates were stirred in a shaker set at

200 rpm for 24 hrs at 4 �C to eliminate physically adsorbed

excess myoglobin-CHAPS clusters. After this step, the

surfactant-modified substrate was washed with DI water.

The surface-modified substrates were dried under a stream

of N2 gas.

2.4. Confirmation of Surface-ModifiedMyoglobin/11-MUA by Surface PlasmonResonance (SPR)

The surface plasmon resonance (SPR) spectroscopy

(Multiskop™, Germany) equipped with He–Ne laser as a

light source (wavelength: 632.8 nm) was operated for con-

firming the myoglobin/11-MUA heterolayer fabrication.

The angle position was affected by the thickness of the

fabricated structure on the Au substrate. When the angle

shift was changed from 38� to 50�, the data was moni-

tored and acquired. A plane face of the glass prism (BK7,

n= 1�5168) was faced with the Au coated glass via match-

ing oil, and it was used to a Kretchmann’s ATR coupler

for experiment. Free electrons from the fabricated surface

were flowed by the external laser area. A change from

the localized electron distribution made a localized elec-

tric field between metal and dielectric interface. The SPR

experiments were carried out at room temperature.19

2.5. Analysis of Myoglobin Layer Immobilized on11-MUA by Raman Spectroscopy

Raman spectroscopy was performed using a NTE-

GRA Spectra (Scanning Confocal Raman Spectrome-

ter, NTMDT, Russia) equipped with an inverted optical

microscope (Olympus IX71) and a liquid nitrogen-cooled

CCD detector. The XYZ scanning range was 100 �m×100 �m×6 �m. Raman spectra were monitored using an

infrared laser that emitted light at a 785 nm wavelength.

Twelve scans of 60 s from 500–1600 cm−1 were obtained

and the mean intensity was used as the Raman signals.

2.6. Topographic Analysis of Myoglobin Layer byAtomic Force Microscopy (AFM)

The surface morphology of the substrates was investigated

by AFM (Digital instruments Nanoscope (R) IV, USA).

AFM was used to investigate the topography of the surface

after protein immobilization with and without surfactant

CHAPS treatment. AFM images were acquired in tapping

mode using 1–10 �-cm Phosphorous (n) doped (Si) tips,

which has a resonant frequencies between 230–305 kHz.

The scanning size was 400 nm× 400 nm and a scan rate

of 1.5 Hz was used.

2.7. Electrochemical Analysis of Myoglobin Layer

The electrochemical analysis was performed with a

CHI660A electrochemical workstation (CH Instruments,

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Nanoscale Biofilm Modification-Method Concerning a Myoglobin/11-MUA Bilayers for Bioelectronic Device Lee et al.

USA) and a standard three-electrode system. The myo-

globin layer self-assembled on the 11-MUA layer was used

as the working electrode. The platinum wire (Bas, USA)

and standard Ag/AgCl electrodes (Bas, USA) were used

as the counter electrode and reference electrode, respec-

tively. All electrochemical experiments were carried out

in the HEPES buffer solution, which was used as the

electrolyte.

3. RESULTS AND DISCUSSION

3.1. Confirmation of Surface-ModifiedMyoglobin/11-MUA by SurfacePlasmon Resonance (SPR)

Previous study, we determined that the optimal concen-

tration of metalloprotein for maximal immobilization was

0.100 mg/ml.13 As a result, all measurements were con-

ducted based on optimized protein concentration. SPR

experiments were carried out bare gold surfaces, 11-MUA

immobilized onto gold surfaces and myoglobin self-

assembled on 11-MUA modified gold substrates. Also,

myoglobin mixed with 10 mM CHAPS solution was immo-

bilized on 11-MUA self-assembled Au surface to determine

the effect of surface modification method as a first treat-

ment method by SPR. Moreover, after CHAPS treatment

by stirring solution, the angle shift of myoglobin/11-MUA

modified substrate was investigated by SPR.

The SPR angle shifts were compared to understand

the immobilization process and the effect of modifica-

tion method by CHAPS in Figures 2(a) and (b). After

11-MUA self-assembled on the Au surface, an angle shift

from 43�000± 0�008" to 43�093± 0�039" was monitored.

Furthermore, after myoglobin was immobilized onto the

11-MUA modified surface, the angle shift from 43�000±0�016" to 43�461± 0�051" revealed. This result implies

myoglobin layer was well adsorbed onto the inorganic

surface via a chemical linker. Also, there was a signifi-

cant angle shift after CHAPS treatment. In case of myo-

globin diluted with CHAPS solution, the angle shift was

drastically decreased from 43�461± 0�051" to 43�287±0�042". This result means that myoglobin which was

bound physically was segregated by surfactant CHAPS.

So, thickness of myoglobin layer reduced compared to

myoglobin without CHAPS treatment. Moreover, in case

of myoglobin/11-MUA layer after CHAPS treatment by

stirring, the angle shift was decremented from 43�461±0�051" to 43�410± 0�014". Figure 2(b) displays the total

angle shifts of these results. Presumably, in case of myo-

globin mixed with CHAPS, this large angle decrement

was due to elimination of myoglobin aggregates. But,

the CHAPS molecule hampered the self-assembly pro-

cess between myoglobin and 11-MUA. So, the myoglobin

layer couldn’t form well. When CHAPS treatment was

stirred after myoglobin/11-MUA formed, the angle shift

was slightly reduced compared to first treatment method,

Fig. 2. Confirmation of the immobilization of the myoglobin layer

self-assembled on a 11-MUA layer depends on CHAPS treatment by

SPR. (a) SPR curve, Red line: Au, Orange line: Au/11-MUA, Yellow

line: Au/11-MUA/myoglobin. Green line: Au/11-MUA/myoglobin mixed

with CHAPS. Blue line: Au/11-MUA/myoglobin stirred by CHAPS

(b) Change of SPR angle.

however, this treatment didn’t inhibit the immobilization

process because CHAPS molecule bound after myoglobin

immobilization was finished. Based on these combined

results, it was concluded that CHAPS treatment was effi-

ciently reduced the protein aggregates.

3.2. Investigation of the Surface-ModifiedMyoglobin Layer Self-Assembled on 11-MUALayer Using Raman Spectroscopy

Figure 3(a) shows the Raman spectra of the 11-MUA self-

assembled layer on the Au substrate in the spectral range

from 500 cm−1 to 1600 cm−1. The peaks characteristic of

the 11-MUA layer were observed in the Raman spectrum,

such as the C–H deformation (1588 cm−1�, C–C stretch-

ing (554 cm−1�, C-Strans stretching (738 cm−1�, CH2

rocking (906 cm−1�, C-Ctrans (1108 cm−1�, C–Cgauche(1293 cm−1� and C–H deformation (1432 cm−1�. This

spectrum is similar to the reported raman spectra of 11-

MUA molecules.20 In agreement with previous reports,21�22

the intense peaks in the Raman spectra of myoglobin

(Fig. 3(b)) were at 578 cm−1, which is related to the Fe–O

stretch, two peaks assigned to symmetric (1374 cm−1� andanti-symmetric (1169 cm−1�� (pyr half-ring), Amide I at

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Lee et al. Nanoscale Biofilm Modification-Method Concerning a Myoglobin/11-MUA Bilayers for Bioelectronic Device

Fig. 3. Confirmation of the immobilization of the myoglobin layer self-

assembled on a 11-MUA layer after CHAPS treatment by Raman spec-

troscopy. (a) raman spectra of an 11-MUA layer immobilized on Au

substrate. (b) raman spectra of a myoglobin layer self-assembled on a

11-MUA layer. (c) raman spectra of a myoglobin layer self-assembled

on an 11-MUA layer after surfactant CHAPS treatment.

approximately 1440 cm−1 and Amide III near 1550 cm−1.

Interestingly, the Raman spectrum of myoglobin after

treatment with CHAPS (Fig. 3(c)) was different from the

spectrum of control Myoglobin under identical conditions,

suggesting that some perturbation in the solubility, coordi-

nation geometry, electronic structure, or all of these factors

occurred during CHAPS treatment.23�24

3.3. The Morphology Analysis of Myoglobin Layerby Atomic Force Microscopy (AFM)

The surface morphology of the surface-modified myo-

globin layer and myoglobin without any treatment immo-

bilized was investigated using AFM. Figure 4(a) shows

an AFM image of the myoglobin self-assembled on the

11-MUA layer. The AFM image of the surfactant CHAPS

treated myoglobin layer was shown in Figure 4(b).

As shown in Figure 3(a), the cluster size of myoglobin

displays when the surface was not treated with CHAPS,

indicating that the myoglobin layer was not well ori-

ented on the surface. However, when myoglobin mixed

with CHAPS, the myoglobin didn’t well immobilize on

11-MUA layer. Figure 4(b) describes an AFM image of

the myoglobin layer mixed with surfactant CHAPS. The

cluster sizes of myoglobin were roughly 5 nm to 15 nm.

In this case, the myoglobin layer didn’t immobilized

well. Presumably, the some CHAPS molecules bound with

hydrophilic part of myoglobin molecule.17 When surfac-

tant CHAPS treatment after myoglobin immobilized was

performed, the myoglobin layer was well oriented and its

cluster sizes were roughly between 30 nm to 50 nm. These

results indicate that physically absorbed proteins were suc-

cessfully removed after treatment of the myoglobin immo-

bilized 11-MUA layer with CHAPS. With these results,

the surfactant CHAPS affects the surface morphology and

aggregation of myoglobin layer.

3.4. The Speculation of Electrochemical PropertyUsing Cyclic Voltammetry (CV)

The cyclic voltammogram was used to measure the elec-

trochemical properties of the myoglobin layer immobilized

on the Au electrode with and without CHAPS treatment.

When CHAPS treatment was not used, reversible oxida-

tion and reduction peaks of the myoglobin were observed

in the voltammogram, as shown in Figure 5(a). Based on

our previous work,13 0.10 mg/ml of protein was immobi-

lized on the 11-MUA/gold substrate and the voltammetric

experiment was carried out using 10 mM HEPES buffer

as the electrolyte. In addition, a scan range from 600 mV

to −100 mV was used with a 50 mV/s scan rate.

When the surface was not subjected to CHAPS treat-

ment, the oxidation and reduction potential of the myo-

globin layer were 462 mV and 213 mV, respectively

(Fig. 5(a)). In case of myoglobin mixed with CHAPS

treatment, the redox potential was drastically attenuated

compared to previous case. The oxidation potential was

119 mV and reduction potential was 302 mV respec-

tively. Figure 5(b) depicted the decreased redox poten-

tial. Presumably, this phenomenon was originated from

the too many CHAPS molecules bound to the hydrophilic

patch of myoglobin region. So, the myoglobin can’t pos-

sible to immobilize to the carboxyl group of 11-MUA

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Fig. 4. Surface morphology of (a) the myoglobin layer self-assembled on an 11-MUA layer (b) the myoglobin mixed with CHAPS solution, and then

immobilized. (c) the effects of CHAPS treatment on the myoglobin layer self-assembled on the gold substrate via an 11-MUA layer.

owing to presence of CHAPS. As a result, the treat-

ment method of myoglobin mixed with CHAPS was not

suitable to modification-method for making well ordered

and well oriented nanoscale biofilm. So, we finally deter-

mined that optimal modification method is immobilized

onto the myoglobin/11-MUA after CHAPS treatment.

When CHAPS treatment by stirred with shaker was used,

the oxidation and reduction potential of the myoglobin

layer were 231 mV and 478 mV, respectively (Fig. 5(c)).

A comparison of the these oxidation and reduction poten-

tials clearly indicate that there were some differences

regarding the redox properties of the myoglobin layer due

to the elimination of the physically adsorbed myoglobin

clusters. After CHAPS treatment, the redox potential was

reduced, but still maintained its original characteristics.

The stable potentials observed from the cyclic voltammo-

gram show that the proteins were efficiently immobilized

onto the 11-MUA/gold surface after CHAPS treatment.

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Lee et al. Nanoscale Biofilm Modification-Method Concerning a Myoglobin/11-MUA Bilayers for Bioelectronic Device

Fig. 5. Cyclic voltammogram of (a) the myoglobin layer self-assembled

on an 11-MUA layer (b) the myoglobin mixed with CHAPS solution, and

then immobilized. (c) the effects of CHAPS treatment on the myoglobin

layer self-assembled on the gold substrate via an 11-MUA layer.

Thus, the use of surfactant treatment during protein immo-

bilization prevents the physical adsorption of proteins to

the protein layer. With these results, the stable electri-

cal properties of myoglobin on the 11-MUA layer after

CHAPS treatment imply that surfactant treatment can pro-

duce very stable and well oriented protein layers for bio-

electronic device application.

3.5. The Determination of the Treatment Method

The surface morphology of the surfactant-treated surface

was investigated by AFM to determine the CHAPS effect

in previous session. In this session, we compared the char-

acteristics dependence on different CHAPS treatment and

Figure 6(a) shows the graph considering size distribution

about these treatment results and Figure 6(b) is table for

characteristics depending on film modification methods.

The size analysis was measured ten times per each sample.

A blue colored lozenge displays a cluster size distribu-

tion of myoglobin aggregates. The minimum aggregates

size is approximately 111.44 nm and maximum size is

198.27 nm. An average cluster size of myoglobin aggre-

gates 151.53 nm within this range without any treatment.

However, when myoglobin was treated by stirring CHAPS

solution, the cluster size was drastically decreased com-

pared to without any treatment. In this case, minimum

cluster size and maximum size are 22.69 nm to 53.12 nm.

The average cluster size is 34.78 nm when self-assembled

myoglobin stirred in 10 mM CHAPS. Also, if myoglobin

mixed with 10 mM CHAPS solution, then, cluster size was

more decreased. The minimum size of myoglobin aggre-

gates is 5.72 nm and the maximum size of myoglobin clus-

ters is 16.99 nm. In case of 5.72 nm, the myoglobin just

aggregates 2 or 3 molecules. It will be helpful for mak-

ing the single molecular bioelectronic device. However, in

the present research, this method was not good compared

to previous treatment method because the redox property

(A)

(B)

Fig. 6. (a) Graph of cluster size depending on protein film modifica-

tion method. Three symbols represent the different treatment methods.

A blue lozenge: cluster size of myoglobin without any treatment. A red

square: cluster size of myoglobin (after self-assembly process, the 10 mM

CHAPS solution was stirred). A green triangle: cluster size of myoglobin

mixed with 10 Mm CHAPS. (b) Table of surface characteristics depend-

ing on different CHAPS treatment.

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of myoglobin did not sustain its original characteristics.

As a result, we finally concluded that the desirable method

is the treatment of self-assembled on myoglobin via 11-

MUA layer stirred in 10 mM CHAPS solution. With this

method, we can possible to make a well ordered and ori-

ented protein film for making a bioelectronic device.

4. CONCLUSION

In this study, a surface-modified methodology was devel-

oped using the surfactant CHAPS to remove protein aggre-

gates for bioelectronic device. To assess the effect of

CHAPS treatment, the surface topology was examined by

AFM. As a result, CHAPS treatment was shown to reduce

protein aggregation on the surface. The composition of the

fabricated surface was analyzed by Raman spectroscopy

to confirm the successful fabrication of the layer of myo-

globin self-assembled on the 11-MUA layer. The surface-

modified myoglobin layer maintained its stable redox

properties by CV. With these results, it was shown that the

surfactant CHAPS did not alter the redox properties of the

immobilized myoglobin layer. These results also proved

that the surface-modified bioelectronic device was robust

and well orientation. This surface-modified myoglobin film

holds promise for use as a novel nanobiochip that displays

an intrinsic switch function.

Acknowledgment: This research was supported

by The Nano/Bio Science and Technology Program

(M10536090001-05N3609-00110) of the Ministry of Edu-

cation, Science and Technology (MEST), by the National

Research Foundation of Korea (NRF) grant funded by the

Korea government (MEST) (2011-0000384) by the project

of National Junior research fellowship which National

Research Foundation of Korea conducts from 2011.

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Received: 17 May 2010. Accepted: 21 June 2011.

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