M. W. WANG ET AL.
Copyright © 2012 SciRes. ENG
Figure 6. Testing at different times for stability.
25days, 30days, 40days, 45days, we can see that:the enzyme
electrode at 1day, 10days, 15days is no obvious differece for
testing the same substrate, but after 20days, the current is ob-
vious reduced and has deviated from the standard curve, so the
retention time of this electrode in 4°c environment is 15 days.
Using polypyrrole as matrix, with the principle of electrostatic
adsorption, we make the biosensor modified by enzyme for
deteacting formaldehyde. In the biosensor,carbon nanotubes
and formaldehyde dehydrogenase are immobilized on the sur-
face of carbon eletrode, and nafion solution capped to prevent
leakage of carbon nanotubes and enzyme. The sensor with for-
maldehyde dehydrogenase modified is simple and easy ,with a
good linear range, and also have practical value. However,
there is some room for improvement. If we can fix NAD+ and
glutathione with formaldehyde dehydrogenase on the surface of
electrode, we don’t need to add them for test each time. The
purity of enzyme solution is also need to improve, which may
increase t he response range of the substr ate concentr ation.
The authors would like to thank the Ministry of Science and
Technology of the People’s Republic of China (2009GJA10047),
Tianjin Municipal Science and Technology Commission
(09ZCZDSFO4200), Tianjin Municipal Education Commission
(SB20080035) and the Tianjin University of Science and
Technology to support the work.
 JIANG Zhongfa, YUAN Wenjun, ZHANG Benyan. Progress of
study on the relationship between Indoor air formaldehyde
Pollution and Leukemia[J] , Journal of Environment and Health,
2008,25(3): 276-278 (in Chinese).
 ZHAI, Jinxia, ZHANG Chuanmu, ZHANG Peng. Acute effects
of formaldehyde in anatomy laboratory on student health[J].
Journal of Environment and Health, 2008,25(2): 141-143 (in
 Yang J，Zhang B，et a1．Cloning and Expression of Pseudo-
monas fluorescens 26-2 lipase gene in Pichla paaoris and cha-
racterizing for transosterification．Appl Biochem Biotechnol，
 Mitsubayashi K, NishioG, SawaiM, A bio-sniffer stick with
FALDH (formaldehyde dehydrogenase)for convenient analysis
of gaseous formaldehyde[J] . Sensors and ActuatorsB, 2008,
130( 1 ) : 32~ 37.
 Boukerma K，Piquemal J Y，Chehimi M M，et al．Synthesis
and interfacial properties of montmorillonite/polypyrrolenano-
 R en X Z，Zha o Q，Liu J H，et al．Prepa ration of polypyrrole
nanop-articles in reverse micelle anditsapplication to glucose
biosensor［J］．Journal of Nan osc ienc e and Nanot echn olog y，
 Wang S G,Zhang Q,Wang R L,et al.A Novel multi-walled car-
bonnanotube-based biosensor for glucose detection[J].Biochem
BiophysRes Commun,2003,3 11(3):572 ~576.
 ZHANG Shu-ping, ZHAO Yan, MAJie1, LIUXiao-hui,
WANGMeng-fei, LIUWei. Study on performance of
layer-by-layer self-assembled electrodein detection of thiocho-
line[J].Modern Chemical Industry,2011,Jan,31(1):88~92
 William G.Gutheil, Elvin Kasimoglu, and Permila C.Nicholson.
Induction of Glutathione-Dependent Formaldehyde Dehydroge-
nase Activity in Escherichia coli and Hemophilus influenza[J].
Biochemical and biophysical research communications 238,
 William G.Gutheil,Barton Holmquist,and Bert L.Vallee. Purifi-
cation, Characterization, and Partial Sequence of the Gluta-
thione-Dependent Formaldehyde Dehydrogenase from Esche-
richia coli: A Class I11 Alcohol[J]. Biochemistry 1992, 31,
 Shi yintao,Yuan ruo,Wang na, The biosensor based on polythio-
nine Nano Au and horseradish peroxidase modified for detecting
Hydrogen peroxide[J], Southwest China Normal Universi-
 hou guoqing, The biosensor based on polyvinylpyrrolidone/Nano
Au and horseradish peroxidase modified for detecting Hydrogen
peroxide[J], S outhwest China Normal University,2010,36,4.
 M. Ben Ali, M. Gonchar, G. Gayda, S. Paryzhak, M.A. Maaref,
N. Jaffrezic-R enault , Y. Korp an . Forma ldehyde-sensitive sensor
based on recombinant formaldehydedehydrogenase using capa-
cit anc e versu s volt age mea su remen ts[ J] . Biosen sor s and Bioelec-
tronics 22 (2007) 2790–2795
 Kohji Mitsubayashi, Genki Nishio, Masayuki Sawai, Elito Ka-
zawa . A biochemical sniffer-chip f or conveni ent analysis of ga-
seousformaldehyde from timber materials[J]. Microchim Acta
(2008) 160: 427–433.
 Lilach Bareket, Ada Rephaeli, Gili Berkovitch, Abraham Nu-
delman, Judith Rishpon. Carbon nanotubes based electrochemi-
cal biosen sor for detec tion of formaldeh yde rel eased from a ca n-
cer cell line treated with formaldehyde-releasing anticancer pro-
drugs[J]. Bioelectrochemistry 77 (2010) 94–99.
 Yar oslav I. Korpan & Olexand r O. Soldatki n & Olga F. Sosovs-
ka & Halyna M. Klepach . Formaldehyde-sensiti ve conductome-
tric sensors b ased on commerc ial an d recombi nant formaldehyde
dehydrogenase[J]. M ic r o chim Acta (2 01 0) 170:33 7–344.