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 (R = 0.968 and R = 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.