Use of Dual-Force Aggregation as a Multiplexed, Rapid Point-of-Care Screening Method for White Blood Cell Counting from Whole Blood Samples

Background: Enumeration of blood cells is an integral metric for evaluating patient health and can be used to screen for a wide range of diseases and conditions. Conventional methods rely on large, expensive, and complicated instrumentation that requires trained technicians and is not amenable to point-of-care analysis. This work demonstrates the use of a multiplexed, bead-based assay for both rapid white blood cell (WBC) count screening and accurate, multiplexed WBC counts for point-of-care analysis. Methods: Blood samples were lysed and diluted before being incubated with silica-coated magnetic particles under chaotropic conditions, a rotating magnetic field, and a source of agitation. The resulting bead aggregation was imaged and correlated to a known WBC count. After establishing standard curves, the WBC count for 18 whole blood samples were determined by this method and compared to values obtained conventionally. Results: When the optimal dilution factor for lysis of whole blood samples was established, 17 of 18 samples (94.4%) were correctly screened and categorized as having high, typical, or low WBC count, while 14 of 18 samples were within 16% of the reported clinical values. The developed system provides analysis of 13 samples in <3 min with a total analysis time of approximately 10 min (including incubation and dilution) and represents comparable throughput to conventional instrumentation, while providing point-of-care capability with reduced size (14 x 21 x 14 cm) and simplicity. Conclusions: This work demonstrates the potential for a multiplexed, bead-based assay to be used as a rapid, point-of-care screening method for WBC counting from whole blood samples.