Multiplexed Detection of Fe3+, Cobalamin and Folate Using Fluorescent Nanoprobe-Based Microarrays and a Smartphone

This work reports on a smartphone-based quantitative POCT system which consists of a paper-based microarray chip, a homemade LEGO dark-box, and a smartphone installed with custom-designed FChip-APP, for on-site quantitation of Fe 3+ , Vitamin 12 (VB 12 ), and folic acid (FA). Collection and automatic analysis of fluorescence turn-off response of three kinds of fluorescent nanoprobes which are coated onto filter papers by a smartphone-based device is the principle behind this study. The POCT system exhibits good analytical performance for multiplexed analysis of Fe 3+ , VB 12 and FA with a wide linear range (Fe 3+ , 1.0–14.0 μg mL −1 ( R 2  = 0.983); VB 12 , 1.35–40.0 μg mL −1 ( R 2  = 0.991); FA, 2.0–26.0 μg mL −1 ( R 2  = 0.994)) and low detection limit (Fe 3+ , 0.35 μg mL −1 ; VB 12 , 0.47 μg mL −1 ; FA, 0.56 μg mL −1 ). The cost and weight of the whole system are ~ $220 and ~ 600 g per set, highlighting its cost-effectiveness and portability. The simple operation procedures and user-friendly interface of the FChip-APP validate the ease-of-use feature of the reported system. This versatile smartphone-based quantitative POCT system provides a cost-effective and easy-of-use method for screening the context-specific causes of anemia and thus its effective interventions in the future, especially in resource-limited areas.