A Lateral Flow-Based Whole Blood Sample Preparation for Surface Plasmon Resonance Sensing of Ferritin in Frequent Blood Donors

Measurements from whole blood remain challenging with plasmonic techniques, especially for point-of-care (POC) measurements where infrastructure is limited. To address this need, we developed a portable POC surface plasmon resonance (SPR) assay for rapid ferritin quantification from whole blood that uses a lateral flow-based sample preparation strip to collect an eluate from whole blood. The concept is shown with clinical samples for monitoring iron deficiency anemia (IDA), a prevalent global health concern considered with care by blood banks, for which rapid POC quantification has yet to be achieved. The SPR assay detected ferritin concentrations in the ng/mL range from whole blood in 30 min, sufficient to discriminate concentrations at the clinically relevant threshold for IDA. Measurements from eluted blood showed good agreement with centrifuged serum and enzyme-linked immunosorbent assay (ELISA) results, allowing clear classification between deficient and normal ferritin levels despite minor variability among clinical samples collected from blood donors. With its portability, short analysis time, and minimal sample preparation, this method demonstrates strong potential for on-site protein sensing, as exemplified for ferritin screening at blood drives with minimal and simple blood preparation, providing a pathway toward future development of point-of-care tools for improved assessment of donor iron status.