Rapid microfluidic fluorescence detection platform for determination of whole blood sodium

A novel detection platform consisting of a microfluidic fluorescence reaction chip (FR-chip) and a miniaturized analysis system is proposed for the determination of sodium ions (Na+) in whole human blood samples. In the proposed method, a rapid reaction of sodium green (SG) reagent with Na+ is induced in the microfluidic FR-chip to produce a SG-Na+ complex. The Na+ concentration is then determined using the miniaturized analytical system based on the maximum fluorescence peak of the reaction compound at a wavelength of 533 nm. The experimental results obtained for artificial serum samples with Na+ concentrations ranging from 10 to 200 mM show a relationship between Na+ concentration (Y) and fluorescence intensity (X) as follows: Y = 190.5 ln(X) + 90.15. The correlation coefficient (R2) is 0.9956, and the limit of detection (LOD) is 2.8 mM. Furthermore, the detection results obtained for 90 whole blood samples from chronic kidney disease (CKD) patients exhibit a high level of consistency (R2 = 0.9806) when compared to the detection results obtained using a traditional indirect ion-selective electrode (ISE) method. Overall, the results confirm that the current microfluidic fluorescence detection platform offers a convenient and highly sensitive approach for the point-of-care (POC) monitoring of whole blood Na+ concentrations.