Serologic and Phenotypic Analysis of Blood Types Via Silicon Nanophotonics
Authors: Kirk James T , Lannert Kerry W , Ratner Daniel M , Johnsen Jill M 
Published: October 2019

Abstract
Tens of millions of donor and patient samples are tested yearly to establish blood type compatibility between donor and recipient and to protect recipients from blood-borne infectious diseases. Blood type testing, particularly donor testing, is traditionally based in centralized clinical laboratories. However, current blood typing methods are encumbered by reagent availability, cost, technical training requirements, and time, placing a costly burden on the medical system. To address practical needs in blood typing, we have developed a multiplexed blood analysis platform using a low-cost and scalable silicon photonic biochip. This study investigates the use of silicon microring sensors to capture, detect, and quantify specific red blood cell (RBC) membrane antigens and anti-blood type antibodies from blood.
To validate ABO blood phenotyping, microring resonators were streptavidin coated and functionalized with biotinylated anti-A IgM or biotinylated anti-B IgM antibodies. First, the response of anti-A/B functionalized microring resonators to characterized RBC membranes (RBC ghosts, 108 cells/ml) were measured in real-time (Figure 1). The biosensor arrays also exhibited minimal non-specific adsorption of RBC membrane fragments to the sensor surface. Microring resonators were shown to be suitable for identifying RBC ABO phenotype from donor blood samples.
For ABO serologic analysis, silicon chips were functionalized with synthetic multivalent polymeric blood group antigens to serve as capture elements for circulating anti-ABO antibodies. Each chip also had sensors functionalized with biotinylated Protein A (btn-ProtA) and a biotinylated polyacrylamide polymer scaffold (btn-paa) to serve as on-chip positive and negative controls, respectively. The multiplexed biosensor chips were exposed to 100mL of plasma, followed by an anti-human-IgM antibody to enhance detection and quantification of antibodies bound to the surface. The resonance shift in each microring resonator was monitored over time, and the sensor response of the polymeric A and B blood group antigens was normalized to the control sensors. Figure 2 illustrates the levels of bound anti-A and anti-B for a panel of donor blood samples with varying ABO blood type, expressed as a relative shift in sensor resonance wavelength. These results demonstrate the detection of the naturally occurring' anti-A/B IgM antibodies for each respective ABO blood type.
We have demonstrated that microring resonator biosensor arrays can quantitatively determine the donor ABO phenotypic and serologic status while incorporating on-chip controls for process standardization. Our work serves as proof-of-concept that a multiplexed silicon nanophotonics platform can rapidly detect both RBC antigens and anti-RBC antibodies in biological samples. This method has the potential for broad applicability in hematology and transfusion medicine for blood typing, quantitative monitoring of specific antibodies, and pathogen screening.
Figure 1 Figure 1.
Figure 2 Figure 2.

Disclosures
No relevant conflicts of interest to declare.