A portable 3D-printed pretreatment device combined with graded lateral flow assay for detection of S. aureus

There is a need for facile yet reliable bacterial pretreatment and signal-graded strategies for current pathogens' point-of-care testing (POCT). Herein, we present a multifunction and portable 3D-printed magnetic separation device with graded lateral flow assay (LFA) for semi-automated pretreatment and rapid detection of Staphylococcus aureus (S. aureus) in food. The 3D-printed pretreatment device allows purification and enrichment of the palladium@platinum nanoparticles (Pd@Pt NPs)-antibody-S. aureus complex. The recovery rate was 81.7–96.1% in actual food samples. Pd@Pt NPs-mediated signal amplification immunoassay achieved graded detection of S. aureus, reducing the detection limit from 103 CFU/mL to 102 CFU/mL, corresponding to the highest safety limit value (M) and acceptable level limit value (m) of S. aureus in many countries and organizations, respectively. This study paves the way for cost-effective and sensitive POCT with multiplexing potential in applications ranging from pretreatment of samples in the complex matrix as well as foodborne pathogens graded and rapid analysis.