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.