Microfluidic aptasensor POC device for determination of whole blood potassium

An integrated microfluidic Au nanoparticle (AuNP) aptasensor device is proposed for monitoring the concentration of potassium (K⁺) ions in the bloodstream of patients with chronic kidney disease (CKD). In the proposed detection device, the AuNPs in the AuNP/aptamer complex are displaced by the serum K⁺ ions and react with NaCl to produce a color change in the detection region from which the K⁺ ion concentration is then inversely derived. The microfluidic device comprises two main components, namely an AuNP aptasensor PMMA (Poly(methyl methacrylate))/paper-microchip and a colorimetric analysis system for the quantitative detection of K⁺ ion concentration in whole blood. The functions of PMMA/paper microchips include reagent storage, K⁺ ion/aptamer reaction, and separation of serum from whole blood samples (blood filter). Experimental results show that the microfluidic device provides a linear response over the K⁺ ion concentration in range of 0.05-9 mM in artificial serum and has a detection limit (LOD) of 0.01 mM. Moreover, the detection results obtained for the 137 whole blood and 287 serum samples of CKD patients are very consistent (R² = 0.968 and R² = 0.980) with the measurement results obtained using an ion-selective electrodes (ISE) method. Results confirm that the current microfluidic aptasensor device provides a highly-sensitive and convenient method for performing the point-of-care (POC) monitoring of the whole blood K⁺ ion concentration.