Smartphone-based preeclampsia diagnosis through detection of dual biomarkers - nephrin and podocalyxin.

Preeclampsia (PE) causes approximately 15% of maternal deaths globally, with disproportionately high mortality in low- and middle-income countries. Current diagnostic protocols require laboratory infrastructure and trained personnel, excluding women in resource-limited settings. We developed a smartphone-integrated dual-biomarker lateral flow assay (LFA) platform for simultaneous quantification of nephrin (NPHS1) and podocalyxin (PODXL), two podocyturia-associated biomarkers with established clinical cut-off values of >304.6 ng/mL and >59.5 ng/mL, respectively. Six monoclonal antibodies were generated via hybridoma technology and screened to identify optimal capture-detection pairs. Selected antibody-functionalized gold nanoparticles (Ab@AuNPs) were assembled into sandwich immunoassay strips on nitrocellulose membranes. The assay detected both biomarkers across 0-1,000 ng/mL, with LODs of 2.41 (NPHS1) and 2.27 ng/mL (PODXL) and sigmoidal fits (R2 = 0.97 and 0.98). Both biomarkers showed strong correlation with ELISA (R2 > 0.96) and high specificity against urinary interfering proteins. Spiked human urine samples yielded a high correlation (R2 > 0.99) between the added and found concentrations. A reference card-smartphone reader compensates for ambient lighting without specialized instruments. Both targets are resolved on one strip within 15 min, enabling early PE screening without laboratory equipment.