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

Itis an urgent need to develop simple and high-throughput methodsfor simultaneously screening and detecting multiple or groups of sulfonamides(SAs) in animal-derived foods since various SAs were alternately usedin animal husbandry to avoid generating drug resistance. We hereindeveloped a novel HCl-reduced nicotinamide adenine dinucleotide I(NADH)-ascorbic acid (AA)-mediated gold nanobipyramids (AuNBPs) growthsystem, which can precisely regulate the growth rate of AuNBPs, togenerate two colorful and stable AA-corresponding multicolor signalchannels with different sensitivities. Based on the HCl-NADH-AA-mediatedAuNBP growth system, we further developed a dual-channel multicolorimmunoassay for simultaneously realizing rapid screening and detectionof 5 SAs (sulfamethazine, sulfamethoxydiazine, sulfisomidine, sulfamerazine,and sulfamonomethoxine) by using a paper-based analytical device forsensitively and stably reading out the signal and a broad-specificityanti-SAs antibody as a bio-receptor. The developed immunoassay hasmore color changes, a wider linear range, excellent specificity andstability, and two multicolor signal channels (L-channel and H-channel)with different sensitivities. The H-channel exhibited 7-8 SAs-correspondingcolor changes and can be used to detect 5 target SAs with a visualdetection limit of 0.1-0.5 ng/mL and a spectrometry detectionlimit of 0.05-0.16 ng/mL. The L-channel exhibited 7-9SAs-corresponding color changes and can be used to detect 5 targetSAs with a visual detection limit of 2.0-6.0 ng/mL and a spectrometrydetection limit of 0.40-1.47 ng/mL. The developed immunoassaywas successfully used to simultaneously screen and detect low-concentrationand high-concentration of target SAs in milk and fish muscle sampleswith a recovery of 85-110% and an RSD (n =5) < 8%. The visual detection limit of our immunoassay is muchlower than the maximum residue limit of total SAs in edible tissue.All above features make our immunoassay a promising assay for simultaneouslyrealizing the rapid screening and quantitative determination of multipleSA residues in food by bare eye observation. It must be mentionedthat our immunoassay may be expended as a general method for the simultaneousvisual screening and detection of other drugs using the correspondingantibody as a recognition probe.

Automated summary

A novel growth system using HCl-NADH-AA mediated gold nanobipyramids was developed, enabling the simultaneous screening and detection of five sulfonamide drugs with two multicolor signal channels.