Development of a Simple, Fast, and Quantitative Lateral Flow Immunochromatographic Strip for Folic Acid

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Development of a Simple, Fast, and Quantitative Lateral Flow Immunochromatographic Strip for Folic Acid Zu-Pei Liang 1,2 & Wu-Zu Ha 3 & Zhi-Li Xiao 1 & Hong-Tao Lei 1 & Yu-Dong Shen 1 & Yuan-Ming Sun 1 & Hong Wang 1 & Jin-Yi Yang 1 & Zhen-Lin Xu 1

Received: 20 October 2016 / Accepted: 9 January 2017 # Springer Science+Business Media New York 2017

Abstract Folic acid (FA) is an important B vitamin naturally found in foods and also used in dietary supplements and food fortification. To monitor FA content is important to guarantee food quality and also to prevent its abuse in dietary supplements. In this work, we developed a simple and robust lateral flow immunochromatographic assay (ICA) for the routine screening of FA in food samples. FA was conjugated to carrier protein as immunogen and used to produce specific polyclonal antibody (pAb). The pAb was conjugated with gold nanoparticle and used to develop a lateral flow ICA. After the careful optimization of ICA conditions, the assay showed an IC50 of 51.8 ng mL−1 and linear range from 23.4 to 114.5 ng mL−1 for FA in assay buffer, with the assist of a DY6510 strip reader within 8 min. Using milk powder as a matrix model, after a 15-fold dilution to eliminate matrix effect, the ICA showed intra-assay recoveries from 94.2 to 107.0% with coefficient of variance (CV) below 15% and inter-assay recoveries from 91.4% to 111.3% with CV below 18%. Good agreement was obtained between the results of ICA and ciELISA and

Zu-Pei Liang and Wu-Zu Ha have equal contribution. Electronic supplementary material The online version of this article (doi:10.1007/s12161-017-0804-7) contains supplementary material, which is available to authorized users. * Zhen-Lin Xu [email protected] 1

Guangdong Provincial Key Laboratory of Food Quality and Safety, South China Agricultural University, Guangzhou 510642, China

2

Guangdong Testing Institute of Product Quality Supervision, Guangzhou, China

3

College of Chemistry and Chemical Engineering, Wuhan Textile University, Wuhan 430073, China

standard HPLC. It is an ideal screening tool for the fast monitoring of FA in a simple, fast, and low-cost manner. Keywords Folic acid . Polyclonal antibody . Immunochromatographic assay . Quantitative detection

Introduction Folic acid (FA) is an important B vitamin made up of 2-amino4-hydroxyl-6-methylpterin, para-amino benzoic acid, and glutamic acid. It is transformed into tetrahydrofolic acid in the human body and participated in formatting amino acid and nucleic acid (Iyer and Tomar 2009). FA exists in a large variety of foods including green leafy vegetables, fruits, meat products, beans, fermented dairy products, and cereals (Nasr et al. 2012), but the content of FA in natural foods is not high, which dissatisfies with demands of the human body. FA deficiency has been associated with a number of health disorders such as mental confusion, diarrhea, irritability, behavior disorder, and headache or nerve damage (Zhang et al. 2008). Besides, insufficient intake of FA can lead to neural tube defects in deve