Paper-based multicolor sensor for on-site quantitative detection of 2,4-dichlorophenoxyacetic acid based on alkaline phosphatase-mediated gold nanobipyramids growth and colorimeter-assisted method for quantifying color

Regulating the Growth Rate of Gold Nanobipyramids via a HCl-NADH-Ascorbic Acid System toward a Dual-Channel Multicolor Colorimetric Immunoassay for Simultaneously Screening and Detecting Multiple Sulfonamides

“…The PAD was fabricated by referring to previous method . In brief, an absorbent cotton layer and a nylon membrane were placed on an unprocessed acrylic plate in order, and then a processed acrylic plate, which has 96-holes and each hole was glued with a silicone seal on its edge, was fixed on the top layer by clips (see Figure S2 in the Supporting Information).…”

“…The PAD was fabricated by referring to previous method. 39 In brief, an absorbent cotton layer and a nylon membrane were placed on an unprocessed acrylic plate in order, and then a processed acrylic plate, which has 96-holes and each hole was glued with a silicone seal on its edge, was fixed on the top layer by clips (see Figure S2 ) were added to a well of a 96-well plate, which was coated with SA antigen. After incubating at 25 °C for 30 min to perform competitive binding, the well was washed five times with PBST buffer (pH 7.4) and covered with 50 μL of ALP-Ab 2 (50-fold dilution with PBST buffer).…”

“…However, most previous colorimetric immunoassays of SAs presented single color and relied on the monochromic intensity changes of chromogenic substrates such as 3,3′,5,5′-tetramethylbenzidine, which have lower extinction coefficients and poorer accuracy of visual inspection , and thus have lower sensitivity and a narrower dynamic range. − Gold nanobipyramids (AuNBPs) is a penta-twinned gold nanomaterial with a high extinction coefficient. , The sharp tips of AuNBPs make their aspect ratio more sensitive to be changed to generate the shift of longitudinal localized surface plasmon resonance wavelength (λ LLSPR ) and vivid multicolor variations, which can be more sensitively and accurately read out with naked eye observation . Hence, AuNBPs have been widely used to develop multicolor colorimetric methods for the detection of various targets such as proteins, DNA, and small molecules by using growth/etching strategies. − Although the AuNBP-based colorimetric assays exhibited target-related multicolor change and higher visual sensitivity and accuracy, the previous AuNBP-based assays also suffer from the defect of narrow linear ranges and thus could not be used to simultaneously realize the rapid screening and quantitative determination of SAs in animal-derived foods since the SAs in animal-derived foods may vary in a very broad concentration range. − …”

A novel metal–organic framework of Co-hemin for portable and visual colorimetric detection of 2,4-dichlorophenoxyacetic acid

“…Therefore, they are not suitable for rapid on-site detection and screening samples in large numbers. Recently, novel detection methods such as immunoassay techniques, 14 electrochemical methods 15 and colorimetric methods, 16 have been developed to detect 2,4-D in environmental samples. Despite its high efficiency and convenience, an enzyme-based immunoassay technique comes with certain operational limitations such as high cost, thermal instability, short lifetime and low reproducibility.…”

Multi‐emitting fluorescent system–assisted lab‐in‐a‐syringe device for on‐site and background‐free detection of 2,4‐dichlorophenoxyacetic acid

“…With the advantages of low cost, easy fabrication, simple operation, and portability, paper‐based analytical devices (PADs) exhibit great potential in the fields of clinical diagnosis, environmental monitoring, and food safety (Noviana et al., 2021; Zhang, Yang, et al., 2022). Microfluidic PADs, lateral flow assay, and vertical flow assay have been compatible with naked eye, optical, or electrical readout for the on‐site detection of herbicides (Umapathi, Park, et al., 2022; Wei et al., 2021; Ye et al., 2022; Zhang, Li, et al., 2021). For example, Wei et al.…”