A microdevice for rapid optical detection of magnetically captured rare blood pathogens.

Sepsis diagnosis requires development of methods to identify rare pathogen cells in small samples of human blood. Magnetic beads functionalized with pathogen-binding ligands have been used to rapidly isolate microbes from blood; however, it is commonly difficult to optically detect the captured species because the excess numbers of beads required for pathogen binding physically interfere with light transmission after they have been concentrated. Here we describe a microdevice that uses microfluidics combined with optimized magnetic field concentrators and magnetic beads coated with a generic blood opsonin to efficiently capture unknown blood pathogens and spread them into a thin layer suitable for automated optical detection. Using this device, we have been able to detect fungal pathogens in less than three hours after sample collection compared to days with current technology, and with an extremely high sensitivity (<1 cell mL(-1) of human blood).

An extracorporeal blood-cleansing device for sepsis therapy.

Here we describe a blood-cleansing device for sepsis therapy inspired by the spleen, which can continuously remove pathogens and toxins from blood without first identifying the infectious agent. Blood flowing from an infected individual is mixed with magnetic nanobeads coated with an engineered human opsonin--mannose-binding lectin (MBL)--that captures a broad range of pathogens and toxins without activating complement factors or coagulation. Magnets pull the opsonin-bound pathogens and toxins from the blood; the cleansed blood is then returned back to the individual. The biospleen efficiently removes multiple Gram-negative and Gram-positive bacteria, fungi and endotoxins from whole human blood flowing through a single biospleen unit at up to 1.25 liters per h in vitro. In rats infected with Staphylococcus aureus or Escherichia coli, the biospleen cleared >90% of bacteria from blood, reduced pathogen and immune cell infiltration in multiple organs and decreased inflammatory cytokine levels. In a model of endotoxemic shock, the biospleen increased survival rates after a 5-h treatment.