Development of a Lateral Flow Immunochromatographic Strip for Rapid and Quantitative Detection of Small Molecule Compounds

Abstract

Membrane-based lateral flow immunochromatographic strips (ICSs) are useful tools for low-cost self-diagnosis and have been efficiently applied to toxin, physiological index and clinical biomarker detection. In this protocol, we provide a detailed description of the steps to develop a rapid, sensitive and quantitative lateral-flow immunoassay (using AuNPs as a marker and mAbs as a probe). The procedure describes the preparation and characterization of colloidal gold, synthesis of the AuNP-mAb conjugate, assembly of the immunochromatographic strip, and methodological investigation of the assay. The results showed that the final strips can be further utilized for the rapid and convenient self-diagnosis of a small molecule, which may provide an alternative tool in the rapid and precise analysis of physiological and biological indices.

Introduction

Membrane-based lateral flow immunochromatographic strips (ICSs) are useful tools for low-cost and rapid detection. The nitrocellulose membrane as the carrier and colloidal gold as markers of immune chromatography rapid diagnostic reagents are the most commonly used POCT (point of care testing) method, and the testing scope of the project is wider. From their original application in monitoring during pregnancy, their use has been extended to monitor blood coagulation state^1,2, myocardial injury³, veterinary medicine⁴, pesticide residues⁵, i....

Protocol

All of the procedures performed in this study were approved by the Ethics Review Committee at the Beijing University of Chinese Medicine (approval number 2017BZYYL00120).

1. Preparation and Characterization of Colloidal Gold

NOTE: For colloidal gold synthesis, as colloidal gold is easily adsorbed on the inner wall of the vessel and is prone to precipitation by impurities, the vessel for synthesis and storage of colloidal gold should be thoroughly cleaned and soaked in acid (40 mL of distilled water, 360 mL of concentrated sulfuric acid, 20 g of potassium dichromate) or subjected to surface passivat....

Results

Characterization of colloidal gold
The prepared colloidal gold solutions were claret red. TEM analyses were used to determine the morphology and shape of AuNPs (Figure 2A-D). Figure 2A and Figure 2B reveal that the particles are polyhedral in shape and uniformly distributed. The average diameter of AuNPs was found to be approximately 14 nm (Figure 2C). A high-resolu.......

Discussion

In this work, we present a protocol for the preparation of mAbs against natural product-derived small molecules. The essential steps and the matters needing attention in the procedure have been outlined, and we have demonstrated the utility of this protocol using the small molecule SSD as an example. Example spectra, TEM images, quantitative results and methodological investigations are shown in representative data. Hence, we have demonstrated that the colloidal gold production, AuNP-mAb conjugation and strip assembly st.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Chloroauric acid solution (HAuCl4)	Tianjin Fu Chen Chemical Reagents Factory	JY-SJ102
bovine serum albumin	AMRESCO	332
centrifuge tube 15 mL	Corning	430645
centrifuge tube 50 mL	Corning	430828
ELISA plates, 96 well	NUNC	655101
Filter paper	Sinopharm	H5072
Glass fibre membranes	Jieyi	XQ-Y6
goat-anti-mouse IgG antibody	applygen	C1308
Nitrocellulose membranes	Millipore	millipore 180
ovalbumin	Beijing BIODEE	5008-25g
PEG20000	Sigma Aldrich	RNBC6325
Pipette 10mL	COSTAR	4488
Pipette 25mL	FALCON	357525
semi-rigid PVC sheets	Jieyi	JY-C104
Sodium citrate	Beijing Chemical Works	C1034
sodium periodate	Sinopharm Chemical	BW-G0008
Sulfo-GMBS	Perbio Science Germany	22324
TipOne Tips 1,000 µL	Starlab	S1111-2021
Tris-HCl	Solarbio	77-86-1
TWEEN 20	Solarbio	9005-64-5