Capture of red blood cells onto optical sensor for rapid ABO blood group typing and erythrocyte counting

ABO blood group typing and erythrocyte counting are essential for blood transfusion especially in the vital lifesaving procedures. Here, we developed a simple, rapid and reliable assay for ABO blood group typing and erythrocyte counting based on localized surface plasmon resonance biosensor. The optical biosensors were constructed by the deposition of gold nanoprisms (GNPs) on glass substrates, and the immobilization of antibodies on the GNPs surface. The sensors were further integrated into a microfluidic chip containing two independent sample cells with anti-isoagglutinins A and anti-B antibodies modified at the bottoms, respectively. The sensing chips coupled with ultraviolet-visible (UV-vis) spectrometer were applied for the identification of blood type A, B, AB and O, respectively; meanwhile, a simple proof-of-principle strategy for quantifying red blood cells (RBCs) through the optical biosensors were demonstrated with series of RBCs dilution, and observed by UV-vis spectra. The limit of detection for erythrocyte counting was as low as ∼104 cells/mL (R2 = 0.99). Additionally, we compared our sensing results with those from conventional gel column assay on 7 different blood samples, in which the accuracy of blood typing was 100%. The RBC concentrations estimated by our sensor chips were between 3.9-5.0 × 109 cells/mL, which locates in the normal range of RBCs concentration of human. The LSPR biosensors that we developed are capable of qualitative ABO blood typing and quantitative erythrocyte counting simultaneously, which have great potential to develop a preliminary and lab-training-free biomedical device for rapid clinical diagnosis.