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On-line Access: 2019-01-22

Received: 2018-02-25

Revision Accepted: 2018-05-17

Crosschecked: 2018-12-05

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Citations:  Bibtex RefMan EndNote GB/T7714


Orawon Chailapakul


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Journal of Zhejiang University SCIENCE B 2019 Vol.20 No.2 P.193-204


Novel ractopamine–protein carrier conjugation and its application to the lateral flow strip test for ractopamine detection in animal feed

Author(s):  Pattarachaya Preechakasedkit, Nattaya Ngamrojanavanich, Nanthika Khongchareonporn, Orawon Chailapakul

Affiliation(s):  Program in Biotechnology, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand; more

Corresponding email(s):   nanthika.k@chula.ac.th, corawon@chula.ac.th

Key Words:  Ractopamine, Conjugate of ractopamine and bovine serum albumin (RAC–, BSA), Mannich reaction, Lateral flow strip test, Feed additive

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Pattarachaya Preechakasedkit, Nattaya Ngamrojanavanich, Nanthika Khongchareonporn, Orawon Chailapakul. Novel ractopamine–protein carrier conjugation and its application to the lateral flow strip test for ractopamine detection in animal feed[J]. Journal of Zhejiang University Science B, 2019, 20(2): 193-204.

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author="Pattarachaya Preechakasedkit, Nattaya Ngamrojanavanich, Nanthika Khongchareonporn, Orawon Chailapakul",
journal="Journal of Zhejiang University Science B",
publisher="Zhejiang University Press & Springer",

%0 Journal Article
%T Novel ractopamine–protein carrier conjugation and its application to the lateral flow strip test for ractopamine detection in animal feed
%A Pattarachaya Preechakasedkit
%A Nattaya Ngamrojanavanich
%A Nanthika Khongchareonporn
%A Orawon Chailapakul
%J Journal of Zhejiang University SCIENCE B
%V 20
%N 2
%P 193-204
%@ 1673-1581
%D 2019
%I Zhejiang University Press & Springer
%DOI 10.1631/jzus.B1800112

T1 - Novel ractopamine–protein carrier conjugation and its application to the lateral flow strip test for ractopamine detection in animal feed
A1 - Pattarachaya Preechakasedkit
A1 - Nattaya Ngamrojanavanich
A1 - Nanthika Khongchareonporn
A1 - Orawon Chailapakul
J0 - Journal of Zhejiang University Science B
VL - 20
IS - 2
SP - 193
EP - 204
%@ 1673-1581
Y1 - 2019
PB - Zhejiang University Press & Springer
ER -
DOI - 10.1631/jzus.B1800112

In this work, a novel conjugate of ractopamine and bovine serum albumin (RAC–BSA) has been developed via the mannich reaction, with a mole coupling ratio for RAC–BSA of 9:1. The proposed conjugation method provides a simple and one-step method with the use of fewer reagents compared with other conjugation methods for competitive immunoassays. RAC–BSA conjugation was used to fabricate a competitive lateral flow strip test for RAC detection in animal feed. For sample preparation, RAC was spiked in swine feed purchased from the local markets in Thailand, and methanol and running buffer at a volume ratio of 10:90 was used as extraction buffer. The procedures for sample preparation were completed within 25 min. Under optimal conditions, the limit of detection (LOD), assessed by the naked eye within 5 min, was found to be 1 ng/g. A semi-quantitative analysis was also conducted using a smart phone and computer software, with a linearity of 0.075–0.750 ng/g, calculated LOD of 0.10 ng/g, calculated limit of quantitation of 0.33 ng/g, and good correlation of 0.992. The recoveries were found in the range of 96.4%–103.7% with a relative standard deviation of 2.5%–3.6% for intra- and inter-assays. Comparison of the results obtained by the strip test with those obtained by enzyme-linked immunosorbent assay had a good agreement in terms of accuracy. Furthermore, this strip test exhibited highly specific RAC detection without cross reactivity with related compounds. Therefore, the RAC–BSA conjugation via the mannich reaction can be accepted as a one-step and easy conjugation method and applied to the competitive lateral flow strip test.


方法:通过曼尼希反应产生RAC-BSA结合物,制备竞争型侧向流试纸条.将RAC标记于猪饲料中,以体积比10:90的甲醇:电泳缓冲液作为提取缓冲液,在25 min内完成样品制备.通过裸眼观察定性评估RAC-BSA结合物的免疫应答以及检测灵敏性,通过智能手机和电脑软件(ImageJ)进行半定量分析.
结论:在最佳条件下,侧向流试纸条检测的检出限(LOD)在5 min裸眼评估下为1 ng/g;半定量分析中,其线性范围为0.075~0.750 ng/g,计算的LOD为0.10 ng/g,定量限为0.33 ng/g,且相关性较好(R2=0.992).回收率为96.4%~103.7%,同实验内及不同实验间的相对标准偏差为2.5%~3.6%.通过与酶联免疫吸附法对比,该侧向流试纸条检测结果具有较高的准确性和特异性.因此,通过曼尼希反应制备RAC-BSA结合物是一步的简单的结合法,可用于侧向流试纸条检测法.


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[41]List of electronic supplementary materials

[42]Fig. S1 Results of MALDI-TOF-MS analysis

[43]Fig. S2 Lateral flow strip test for RAC detection using the RAC–BSA(1) prepared via the Mannich reaction and the RAC–BSA(2) prepared using previous method for the immobilization on test line

[44]Fig. S3 TEM image of AuNPs

[45]Fig. S4 UV-vis spectra of AuNPs and monoclonal antibody against RAC–AuNPs conjugated

[46]Fig. S5 Cross reactivity test by loading running buffer, RAC, SAL, CLB, TER, NE, and PHE

[47]Fig. S6 Storage stability after keeping the strip tests for 0 to 5 months after loading running buffer as negative control and 1 ng/mL of RAC as positive control

[48]Fig. S7 Effect of the volume ratio of methanol and running buffer of 0:100, 5:95, 10:90, 20:80, and 40:60 toward the lateral flow strip test

[49]Fig. S8 Relationship between the ∆gray intensity and the concentrations of the non-spiked (0) and spiked RAC in animal feed at 0.075–1.000 ng/g

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