Application of a dual-modality colorimetric analysis method to inkjet printing lateral flow detection of Salmonella typhimurium

Abstract

Lateral flow assay (LFA) color signal quantification methods were developed by utilizing both International Commission on Illumination (CIE) LAB (CIELAB) color space and grayscale intensity differences. The CIELAB image processing procedure included calibration, test, control band detection, and color difference calculation, which can minimize the noise from the background. The LFA platform showcases its ability to accurately discern relevant colorimetric signals. The rising occurrence of infectious outbreaks from foodborne pathogens like Salmonella typhimurium presents significant economic, healthcare, and public health risks. The study introduces an aptamer-based lateral flow (ABLF) platform by using inkjet printing for specially detecting S. typhimurium. The ABLF utilized gold-decorated polystyrene microparticles, functionalized with specific S. typhimurium aptamers (Ps-AuNPs-ssDNA). The platform demonstrates a detection limit of 10² CFU mL⁻¹ in buffer solutions and 10³ CFU mL⁻¹ in romaine lettuce tests. Furthermore, it sustained performance for over 8 weeks at room temperature. The ABLF platform and analysis methods are expected to effectively resolve the low-sensitivity problems of the former LFA systems and to bridge the gap between lab-scale platforms to market-ready solutions by offering a simple, cost-effective, and consistent approach to detecting foodborne pathogens in real samples.

Graphical Abstract

Graphical illustration of the ABLF construction for S. typhimurium detection. a The synthesis process of Ps-AuNPs conjugated with aptamer and sample preparation. b The schematic of ABLF detecting pathogens. c Test interpretation by two image analysis methods. (Created with BioRender.com)