Abstract
In this work, a fully integrated active microfluidic device transforming a conventional 96-well kit into point-of-care testing (POCT) device was implemented to improve the performance of traditional enzyme-linked immunosorbent assay (ELISA). ELISA test by the conventional method often requires the collection of 96 samples for its operation as well as longer incubation time from hours to overnight, whereas our proposed device conducts ELISA immediately individualizing a 96-well for individual patients. To do that, a programmable and disposable on-chip pump and valve were integrated on the device for precise control and actuation of microfluidic reagents, which regulated a reaction time and reagent volume to support the optimized protocols of ELISA. Due to the on-chip pump and valve, ELISA could be executed with reduced consumption of reagents and shortening the assay time, which are crucial for conventional ELISA using 96-well microplate. To demonstrate highly sensitive detection and easy-to-use operation, this unconventional device was successfully applied for the quantification of cardiac troponin I (cTnI) of 4.88 pg/mL using a minimum sample volume of 30 µL with a shorter assay time of 15 min for each ELISA step. The limit of detection (LOD) thus obtained was significantly improved than the conventional 96-well platform.
Highlights
Numerous infectious and immuno-related diseases such as malaria, tuberculosis, cardiac failure, and acquired immunodeficiency syndrome (AIDS) cause approximately fifteen million deaths worldwide every year[1,2]
Since the viscosity of blood differs with age, the capillary-force initiated reaction time in the lateral flow assay (LFA) varies from person to person
This paper presents a pump and valve-controlled LOC device converting a commercial 96-well microplate into a 96-well associated LOC device to execute an unconventional sandwich enzyme-linked immunosorbent assay (ELISA) protocol intended to outweigh the negative aspects of conventional ELISA
Summary
Numerous infectious and immuno-related diseases such as malaria, tuberculosis, cardiac failure, and acquired immunodeficiency syndrome (AIDS) cause approximately fifteen million deaths worldwide every year[1,2]. The association of conventional 96-well plate with LOC counterparts expedites certain unique advantages over the 96-well microplate-based traditional ELISA, such as (i) a tinier reaction chamber inside the 96-well plate that enables ELISA with significantly reduced sample and reagent usage, and assay time compared to conventional 96-well microplate-based ELISA; (ii) the integration of the PDMS pump and valve precisely controls the flow rate addressing the imprecise reaction times of the different assay steps; (iii) as the reaction zone is comparatively small, the non-specific binding of target analyte may be effectively avoided by simple washing steps; and more importantly (iv) the ELISA can be conducted immediately for urgent patients as a POC format separating the 96-well from the entire cartridge
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