Enhanced fully cellulose based forward and reverse blood typing assay

This study presents an enhanced paper-based analytical device (PAD) for forward and reverse group blood typing. The proposed PAD uses a novel methodology, which provides highly reliable results on a fully cellulose based device. The PAD was printed on different cellulose substrates. These substrates were made of different cellulose fibers (sisal and eucalyptus), different grammages, refining steps, and wet additive content. Best parameters were chosen to achieve high reliability on both forward and reverse blood typing. The substrates were patterned with five hydrophilic channels and two hydrophobic areas. For reverse blood typing, the hemoagglutination reaction took place on the hydrophobic surface of the paper before being transferred to the paper web, where together with the forward blood typing tests were all washed with saline solution to read the results by elution. This device allows direct read-out of results; the stains show were agglutination happens. Different blood types were in full agreement between the reverse and forward method and in agreement with traditional methods. The time and simplicity of this methodology confirmed its utility.