Spot Immunomagnetic Enrichment Device for Rapid Detection of Pathogens in Peripheral Blood

Abstract

Microbial infection is a leading cause of mortality and morbidity worldwide. Due to lack of rapid and affordable diagnostics test, patients consume broad spectrum antibiotics without diagnostic confi rmation of the pathogen, leading to development of antibiotics resistance among microbes. Detection of pathogen is challenging particularly when only few cells per mL are present among billion other blood cells. A portable and cost-effective spot immunomagnetic enrichment device has been developed that allows concentration of cells from 1 to 10 mL sample volume up to 10 000× per mL into a small spot inside a disposable millifl uidic capture chip. Salmonella typhi , causative agent for typhoid infection has been used to demonstrate the results. Microbes are specifi cally labeled with antibody-conjugated magnetic nanoparticles and isolated from bulk sample at 200 µL min −1 fl ow rate with >90% capture effi ciency. Isolated cells are swept to a single spot by decreasing the area under infl uence of magnetic fi eld and fl owing a wash buffer. Using this spot enrichment method, 4 CFU of S. typhi cells enriched from 5 mL sample is detected with turnaround time of less than 1 h.

i-scope: a compact automated fluorescence microscope for cell counting applications in low resource settings

“…In the case of cell-count-based diagnostics, a conventional microscope provides a limit-of-detection (LoD) of the order ∼10 6 cells per ml [41]. The i-scope, due to its larger field of view and large area sample scanning feature, offers a 100-fold improvement, enabling quantification of as low as 10 4 cells/ml.…”