Immunochromatographic Dipstick Assay Format Using Gold Nanoparticles Labeled Protein−Hapten Conjugate for the Detection of Atrazine

Abstract

The present study describes a lateral-flow-based dipstick immunoassay format using a novel hapten-protein-gold conjugate for the rapid screening of atrazine in water samples. The immunoassay is based on the competitive inhibition, in which a newly developed hapten-protein-gold conjugate competes with the free antigen present in the sample, for the limited antibody binding sites available at test zone on dipstick membrane, housed in a plastic cartridge. The tracer used as the detection reagent was prepared by first conjugating hapten (a derivative of atrazine) molecules to a carrier protein (bovine serum albumin) via its surface lysine residues and then linking colloidal gold nanoparticles to the hapten-protein conjugate via cysteine residues of the carrier protein. The developed conjugate showed a high level of stability as it did not show any significant loss of activity even after 8 weeks of storage at ambient conditions. The color developed due to conjugate, based on competitive inhibition approach, is correlated with the concentration of atrazine sample. The sensitivity of the developed dipstick was enhanced by gold nanoparticles, as an amplification tag, presenting detection limit of atrazine in standard water samples down to 1.0 ppb level. The kit could serve as a rapid screening methodology for visual screening of atrazine contamination of water samples within 5 min of analysis time, and, when coupled with a portable colorimeter, as an inexpensive semi-quantitative assay. The method reported can be useful for screening a large number of pesticides samples in a very short time in the field.

Evaluation of Nanomaterials-biomolecule hybrids for signal enhancement of impedimetric biosensors

“…Gold-PrA conjugate was prepared as in [3]. GO-PrA conjugates were prepared in the same manner as for Gold-PrA utilizing the highly negatively charge of GO.…”

“…NMbiomolecule hybrid systems, which combine recognition and catalytic properties of biomolecules with these physicochemical properties, are particularly new materials with complimenting properties of both. Nanoparticles (NPs) prepared from different materials that range from metals (Au, Ag) and semiconductors (CdSe, PbS) to dielectric materials (TiO 2 , SiO 2 ) [1][2][3]. Nanoparticles offer several advantages that have attracted widespread interest in their use as labels, including simple chemical processes for biofunctionalization, good biocompatibility and size comparable to most biomolecules [4].…”

Enzyme-linked immunosorbent assay and immunochromatographic strip for rapid detection of atrazine in water samples

“…Immunoassays can meet these requirements. Numerous related methods for the detection of atrazine have been reported, such as enzyme-linked immunosorbent assay (ELISA) [10][11][12][13][14][15], colloidal gold-based immunochromatographic (ICG) strip assay [16][17][18], time-resolved fluorescent immunoassay (TRFIA) [19] and liposome immune lysis assay (LILA) [20]. The specific features of each study are listed and compared in Table 1.…”

Inference of Nonlinear State-Space Models for Sandwich-Type Lateral Flow Immunoassay Using Extended Kalman Filtering

“…[19], [23], [35], and the other is the development of quantitative instruments, see e.g. [4]- [7], [13], [24], [25].…”