Colorimetric LAMP microfluidic chip for detecting three allergens: peanut, sesame and soybean

Abstract

Food allergies can greatly harm people’s health, and therefore detecting allergens in foods is extremely important. By integrating loop-mediated isothermal amplification (LAMP) with a microfluidic chip, we have developed a method for detecting the allergen genes of peanut (Arachis hypogaea), sesame (Sesamum indicum), and soybean (Glycine max) using a colorimetric method suitable for the naked eye, known as the colorimetric LAMP microfluidic chip. In the presence of peanut, sesame, or soybean in the samples, the corresponding reaction well of the microfluidic chip will appear pink, or otherwise remain light brown. This method of detection is specific and can easily distinguish these three allergens from others in foods. The detection limit for peanut, sesame and soybean allergens was 0.4 ng/μL using the LAMP-microfluidic chip. The accuracy of this novel and rapid method was validated using allergenic foods obtained commercially and was comparable with that of the typical TaqMan real-time PCR method.

The Development of Highly Specific and Sensitive Primers for the Detection of Potentially Allergenic Soybean (Glycine max) Using Loop-Mediated Isothermal Amplification Combined with Lateral Flow Dipstick (LAMP-LFD)

“…The only equipment required is a simple thermostatically controlled water bath, heat block, or oven [18,19].With regard to the food and feed sector, mainly LAMP methods for the detection of foodborne pathogens [21,22] and genetically modified crops [23,24] are described. However, a number of reports suggest that LAMP may also be useful for the detection of allergenic foods [25][26][27][28]. LAMP amplicons can be detected by various methods, e.g., agarose gel electrophoresis (AGE) [25,27,28], real-time fluorescence detection using intercalating nucleic acid dyes [26][27][28], microfluidic chips for visual detection based on a pH indicator dye [26], visual detection using intercalating nucleic acid dyes [27], color changes of metal-sensitive indicators, such as calcein [28], and the visual or turbidimeter detection of turbidity formation [24].…”

“…However, a number of reports suggest that LAMP may also be useful for the detection of allergenic foods [25][26][27][28]. LAMP amplicons can be detected by various methods, e.g., agarose gel electrophoresis (AGE) [25,27,28], real-time fluorescence detection using intercalating nucleic acid dyes [26][27][28], microfluidic chips for visual detection based on a pH indicator dye [26], visual detection using intercalating nucleic acid dyes [27], color changes of metal-sensitive indicators, such as calcein [28], and the visual or turbidimeter detection of turbidity formation [24]. AGE and real-time fluorescence monitoring require additional equipment for the reaction confirmation, which compromises the simplicity of LAMP and limits the field-like or on-site applications of this procedure.…”

LAMP-on-a-chip: Revising microfluidic platforms for loop-mediated DNA amplification

“…Mainstream detection methods of LAMP results often rely on naked-eye monitoring to observe precipitates [22], DNA-binding dyes [64], and colorimetric indicators [65]. Off-chip end-point detections are commonly conducted by performing gel electrophoresis [66].…”

“…Food safety and food quality control are, inevitably, an important part of the public-health system. LAMP has been used in food safety detection [26,82e84] including Staphylococcus aureus [85], Salmonella [86e89], E. coli O157 [90], and Vibrio parahaemolyticus [91], as well as food allergens [65].…”

Siphon-Induced Droplet Break-Off for Enhanced Mixing on a Centrifugal Platform

“…Similarly, inherent centrifugation of samples [21][22][23] applied to sample preparation is a particular strength.The technological precursor of these systems are the centrifugal analyzers which became popular in the 1970s and 1980s [24] for automating a very limited number of simple assay steps, on rather macroscopic sample volumes, and readout on a rotor-based instrument. Currently the main areas of application are immunoassays [25][26][27][28], nucleic acid testing [29][30][31][32][33][34][35][36], and cell sorting/identification [37][38][39][40][41][42][43]. These lab-on-a-disc systems make specific use of the interplay of the frequency controlled centrifugal force and capillary action in a surface-functionalized network of micro-channels and cavities.…”