Affinity Functionalized Strings for Blood Purification


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Pathogen reduction is a proactive approach to maximize safety of blood transfusion. Methods of bacterial reduction are available for plasma and platelets but not for red blood cell concentrates and whole blood. We addressed this technology gap by using a novel approach consisting of molecular probes immobilized on nylon filaments (affinity networks) as a means to capture bacteria in suspension. We dyed nylon filaments with 24 dyes with different chemical properties, including acidic, basic, fast, metallic, hydrophobic, and uncharged/polar dyes. We established quality control measures of acceptable ranges of dye incorporation in the nylon network to ensure reproducibility. We performed incubations and microbiology cultures to assess the depletion capability of different affinity networks. Four affinity networks incorporating basic and hydrophobic dyes (pinacyanol chloride, reactive blue 21, sudan IV, alizarin cyanin) depleted more than 90% of E. coli suspended in phosphate buffer saline (PBS, 10 and 100 CFU/mL). Safranin O, methylene blue, alcian blue pyridine variant, and reactive blue 21 dyed nylon networks removed more than 90% of S. epidermidis from PBS (10 and 100 CFU/mL). In several instances, affinity networks removed all bacteria present in suspension. Affinity networks efficiently captured >90% S. epidermidis spiked in plasma at a 10 and 100 CFU/mL concentration, and the combination of sudan IV, alcian blue pyridine variant, and reactive blue 21 functionalized affinity networks had synergistic effects. Affinity network sequestration of lipoteichoic acid (LTA), a major component of gram-positive bacterium cell wall, spiked in model solutions, suggested that LTA is involved in the binding and capture of bacteria. In conclusion, affinity networks functionalized with synthetic dyes is a promising medium to capture bacteria from suspensions and from biological matrices for future application as a pathogen reduction technology. Future work will include a prototype production for a pathogen reduction device.