Hydrogel-integrated microfluidic platform for separation-free colorimetric and distance-based detection of biomarkers in whole blood

Rapid and reliable detection of disease-related biomarkers in whole blood remains a great challenge due to the complex composition of blood. Here, we report a novel point-of-care test (POCT) platform for direct detection of biomarkers in blood sample, in which horseradish peroxidase (HRP) and 3,3′,5,5′-tetramethylbenzidine (TMB) embedded poly(ethylene) glycol diacrylate (PEG-DA) hydrogel were integrated in a specific designed microfluidic chip. In the presence of the biomarkers triggered enzyme-catalyzed product H2O2, a distinct TMB-oxTMB color signal can be captured effectively by smartphone. Meanwhile, ingeniously utilized hydrogel and photothermal oxTMB as “hotplate”, a visual quantitative distance signal can be attained by colored liquid moving driven through the increase in air pressure inside the chip due to heating of the “hotplate”. Besides, the porous hydrogel can serve as a molecular sieve via size exclusion and avoid interference of co-existed biomacromolecules for directly sensing glucose and cholesterol in blood samples. Furthermore, the consistency of the results obtained by colorimetric and distance-based microfluidic assays demonstrates that the platform offered various analytical pathways for biomarkers determination. The detection strategy for biomarkers capable of producing H2O2 indicated it also has great potential in disease diagnosis as a versatile platform.