Poly(dimethylsiloxane) microchip for detection of cholesterol

Abstract

In this work, the rapid detection of cholesterol using poly(dimethylsiloxane) microchip capillary electrophoresis, based on the coupling of enzymatic assays and electrochemical detection, was developed. Direct amperometric detection for poly(dimethylsiloxane) (PDMS) microchip capillary electrophoresis was successfully applied to quantify cholesterol levels. Factors influencing the performance of the method (such as the concentration and pH value of buffer electrolyte, concentration of cholesterol oxidase enzyme, separation voltage, injection time, and detection potential) were carefully investigated and optimized. The migration time of hydrogen peroxide, product of the reaction, was less than 100 s when using 40 mM phosphate buffer at pH 7.0 as the running buffer, a concentration of 0.68 U.mL-1 of the cholesterol oxidase enzyme, a separation voltage of +1600 V, an injection time of 20 s, and a detection potential of +0.5 V. PDMS microchip capillary electrophoresis showed linearity between 38.7 𝜇g·dL-1 (1 𝜇M) and 270.6 mg·dL-1 (7 mM) for the cholesterol standard; the detection limit was determined as 38.7 ng.dL-1. To demonstrate the potential of this assay, the proposed method was applied to quantify cholesterol in serum samples. The percentages of recoveries were assessed over the range of 98.9 % to 101.8 %. Therefore, PDMS microchip capillary electrophoresis, based on the coupling of enzymatic assays and electrochemical detection, is very rapid and sensitive method for the determination of cholesterol levels.