Iron deficiency disproportionately affects women of reproductive age worldwide; however, our ability to diagnose it relies on just hemoglobin measurements for a vast majority of the population. Our objective is to develop a point-of-care low cost test to enable quantitative detection of ferritin in finger-prick blood samples in 15 minutes or less.
The platform consists of a lateral flow immunoassay test strip (consumable) with all the test reagents positioned inside an accessory (reusable) that can be attached to a smartphone. The user places a drop of blood (collected by finger-prick) on the test strip and the sample begins to flow up the strip via capillary action. The sample first interacts with gold nanoparticles coupled to specific antibodies, followed by interaction with two bands of immobilized antibodies to undergo a sandwich ELISA reaction, and a relative color change occurs in the bands. The smartphone camera captures an image of the colored bands and post-processing is performed within a customized app to provide quantitative results on the ferritin concentration.
The calibration test results of the biosensor with standard solutions of ferritin indicates that the calibration curve is linear for ferritin concentrations up to 2000 ng/mL (meeting the required range for iron deficiency cut-off level of 10 ng/mL), with signal saturating at concentrations higher than 4000 ng/mL.
A Smartphone-based platform will enable iron deficiency tests at a low cost in both home-use and field settings or at a community-health clinic, bypassing the need for a cold-chain, expensive laboratory equipment, and trained personnel.