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754 Abstracts / Journal of Biotec

III3-Y-003

olloidal gold-based immunochromatographic assay for detec-ion of ractopamine in swine urine samples

ing Jin 1,2, Weihua Lai 1,∗, Yonghua Xiong 1, Yuan Chen 2, Wenjuaniu 2

State Key Laboratory of Food Science and Technology, Nanchang Uni-ersity, Nanchang 330047, ChinaWuxi Zodolabs Biotech Co., Ltd., Wuxi 214174, China

-mail address: talktolaiwh@163.com (W. Lai).

he aim of this work was to develop a rapid immunochromato-raphic assay for the detection of ractopamine residue in swinerine samples. A wide variety of analytical methods for the deter-ination of ractopamine in different biological matrices have been

escribed (Williams et al., 2004; Shelver and Smith, 2002). Themmunochromatographic test is a competitive binding immunoas-ay. The ractopamine in the urine specimen competes with thentigen coated on the nitrocellulose membrane for the limitedinding sites of the antibody in the conjugate pad. When an ade-uate amount of urine specimen is applied to the sample pad ofhe device, the urine migrates by capillary action through the testtrips. If the ractopamine level in the specimen is below the cutoffevel, the red-colored conjugate will bind to the antigens coatedn the nitrocellulose membrane. A red T line will be formed, whichndicates a negative result. If the ractopamine is present in the urinepecimen at a cutoff level or higher, it will bind to antibodies in theonjugate pad, so that no red line develops in the test region, whichndicates a positive result. Analysis was completed in 10 min. Cutoffevel was 5 ng/ml of ractopamine. The test strip compared to GC-MSave a false positive rate of 3.5% and a false negative rate of 0%. Theross-reactivity rate to ractopamine was 100% while that of other �-drenergic agonists, including clenbuterol, salbuterol, isoprenaline,ilpaterol, mabuterol and fenoterol were all below 0.5%.

eferences

helver, W.L., Smith, D.J., 2002. Application of a monoclonal antibody-based enzyme-linked immunosorbent assay for the determination of ractopamine in incurredsamples from food animals. J. Agric. Food Chem. 50, 2742–2747.

illiams, L.D., Churchwell, M.I., Doerge, D.R., 2004. Multiresidue confirmation of�-agonists in bovine retina and liver using LC-ES/MS/MS. J. Chromatogr. B 813,35–45.

oi:10.1016/j.jbiotec.2008.07.1676

III3-P-002

he pesticide residue monitoring technique based on the sensi-ive nano-biosensors

huping Zhang 1,2,∗, Yi Zheng 1, Liyi Shi 2

University of Shanghai for Science and Technology, Shanghai, ChinaShanghai University, Shanghai, China

-mail address: zhang lucy9999@yahoo.com.cn (S. Zhang).

ano-biosensor based enzyme inhibition technique provided aromising way to detect carbamate pesticides which was both rapidnd simple (Amine et al., 2006). Meanwhile, the excellent electro-atalytic activity and antifouling properties of Carbon nanotubes

CNTs) have been used to improve the electrochemical behav-ors of dopamine, glucose and catecholamine neurotransmittersAmine et al., 2006). So this paper described the self-assemblyechnique to form bilayers of chitosan and MWNTs, which the GCEith electro-deposition of MWNTs (Shu et al., 2008) were fabri-

adcPd

gy 136S (2008) S751–S759

ate by alternatively immersion of GCE in 1% chitosan solution andmg L−1 MWNTs dispersed in pH 9.18 borate buffer solution for5 min (Luo et al., 2005). Then acetylcholinesterase (AChE) wasmmobilized directly to the chitosan/MWNTs bilayer by LBL self-ssembly method, the activity of the immobilized AChE is 0.02 U.o chitosan/MWNTs bilayer has better compatibility to AChE com-aring with PDDA/MWNTs. Meanwhile, when the biosensor ofChE/chitosan/MWNTs/GCE is used to monitor aldicarb pesticides

n vegetable, the detection limit is 10−10 g L−1. So chitosan/MWNTsan be used as a good immobilization material for AChE and the pre-ared nano-biosensor can be used to detect carbamate pesticides

ast and simply.

eferences

mine, A., Mohammadi, H., Bourai, I.s., Palleschi, G., 2006. Biosensors for food safetyand environmental monitoring. Biosens. Bioelectron. 21, 1405–1423.

uo, X.L., Xu, J.J., Zhang, Q., Yang, G.J., Chen, H.Y., 2005. Electrochemically depositedchitosan hydrogel for horseradish peroxidase immobilization through goldnanoparticles self-assembly. Biosens. Bioelectron. 21, 190–196.

hang, Shu Ping, Shan, Lian Gang, Tian, Zhen Ran, et al., 2008. study of enzymebiosensor based on carbon nanotubes modified electrode for detection of pes-ticides residue. Chin. Chem. Lett. 19, 592–594.

oi:10.1016/j.jbiotec.2008.07.1677

III3-P-004

ntibacterial mechanism of polymeric guanidine salts

hongxin Zhou 1, Dafu Wei 2, Anna Zheng 2, Jian-Jiang Zhong 3,∗

State Key Laboratory of Bioreactor Engineering, East China Universityf Science and Technology, Shanghai 200237, ChinaSchool of Materials Science and Engineering, East China University ofcience and Technology, Shanghai 200237, ChinaKey Laboratory of Microbial Metabolism, Ministry of Education, Col-

ege of Life Science & Biotechnology, Shanghai Jiao Tong University,hanghai 200240, China

-mail address: jjzhong@sjtu.edu.cn (J.-J. Zhong).

olymeric guanidine salts provide a safe alternative to other com-on disinfectants (Buxbaum et al., 2006), and they have been

eceiving great attention as antiseptics used in public healthKratzer et al., 2006, 2007). But for their antimicrobial mech-nism, little discussion in literatures is observed, and there islso a lack of related experimental data. In this work, by takingoly(hexamethylenediamine guanidine hydrochloride) (PHMGH),n excellent cationic antimicrobial agent, as a typical example,xperiments were done to provide an insight into the antimicrobialechanism. We studied the interaction of PHMGH with Escherichia

oli strain 8099 by using �-galactosidase activity assay, scan elec-ron microscopy (SEM), transmission electron microscopy (TEM),nd fluorescein-5-isothiocyanate (FITC) fluorescence microscopybservation. The results revealed that the treated cells releasedore intracellular �-galactosidase compared to the control in time

nd dose-dependent manners. In addition, FITC was able to tra-erse the cytoplasmic membrane of treated cells, but not for theontrol intact cells. Membrane structure damage of the E. coli 8099as clearly observed by both SEM and TEM. By SEM, we observed

hat the cell morphology changed significantly, and concave col-apses of treated cells and lots of cell debris were observed at

high concentration of PHMGH. According to TEM, the PHMGHestroyed the integrity of the cell membrane structure, and someells gaps existed in the membrane structure. At the same time,HMGH destroyed the intracellular structure as many tightly con-ensed substances or dense granules were visible inside the cells.