Nanoshell build-up onto non-fixed human red blood cells through the layer-by-layer self-assembly technique for their immunocamouflage

In this study, non-fixed red blood cells (RBCs) were coated with a polymeric shell via the layer-by-layer (LbL) self-assembly technique for their potential application in medical blood transfusion. The polymeric shell is achieved through the alternate adsorption of two oppositely charged polymers; chitosan-graft-phosphorylcholine (CH-PC) and alginate (ALG). The process of film formation was followed by measuring the zeta potential revealing a charge alternation upon the addition of the polyelectrolytes. The integrity of the coated RBCs was assessed with optical microscopy demonstrating similar shapes to uncoated RBCs. Moreover, the percentage of released hemoglobin and adenosine-5'-triphosphate (ATP) in the supernatant were measured and compared to the non-coated RBCs. The results showed that the layers built on the RBCs demonstrated no changes in cellular morphology and integrity. Most importantly, an agglutination test was performed to assess antibodies interaction with coated RBCs. They showed no aggregation suggesting a decrease in antibody recognition of coated RBCs. In summary, a system of two different polymers is successfully able to protect the cells from hemolysis and prevent recognition by the antibodies. This would offer a great opportunity for producing universal RBCs.