Functional Point-of-Care Dried Blood Spot Cards
SUMMARY OF PROBLEM
Currently, blood is collected and stored for further analysis on dried blood spot (DBS) cards. Uses include testing expecting mothers for fetal distress, and newborns for metabolic and congenital disorders; and is a field standard for biobanking and epidemiology.
However, these cards are subject to sampling inconsistencies. Under- or over-filling blood on the marked zones leads to variable diffusion of blood that result in variable levels of analytes in different areas within a marked zone. The variabilities complicate any downstream analyses of the samples at off-site clinical laboratories. In addition, the cards only act as passive storage media with no active functions.
Dr. Charles Mace has developed has fundamentally redesigned DBS cards, making them capable of analysis. These cards are multilayered with paper and porous membranes. They are patterned with a network of channels and functional sample zones that can perform whole blood (e.g. blood typing), plasma (e.g. C-reactive protein), and cellular (e.g. hemoglobin) analyses. Furthermore, the patterned application zones meter sample blood volumes and hematocrit variations. These improved cards can be designed in multiple form factors based on their intended application.
Dr. Mace’s group designed a multilayer device that performed in-line lysis of RBCs by saponin, filtration of cellular particulates by a membrane, coupled oxidation and reduction reactions with ammonium persulfate and ascorbic acid, respectively, and detected (colorimetric) free Fe2+ by ferrozine in a single step. This device and assay configuration produced a visible difference using Hgb standards at various concentrations of relevance to anemia.
This technology can surmount the requirement for multiple (5+) devices and instrumentation for point-of-care diagnostic blood assays. Tufts University is looking for a commercial partner to further develop this technology and expand the capabilities of existing paper-based diagnostics. In doing so, this partnership will likely create several new consumer products.
• fewer variabilities in samples
• not just a passive blood storage medium
• better standardization
• analytical capabilities
• replaces need for multiple devices
IP STATUS US provisional patent application filed (June 2018)