Dual-aptasensor array: optimization of the aptamers immobilization

Abstract

In the present work it is intended to establish the optimal experimental conditions that allow enhancing the performance of an electrochemical dual-aptasensor array for the detection of osteopontin, which has been reported as a cancer biomarker. The aptamer concentration, time and temperature of immobilization onto dual-screen printed gold electrodes (Dual-SPGE), as well as the aptamer-protein interaction time were evaluated using a 2k factorial experimental design. The preliminary results allowed identifying the optimal experimental conditions, namely: (i) aptamer concentration of 0.5 μM for both DNA and RNA aptamers; (ii) incubation temperature of 4ºC; (iii) time for aptamer immobilization onto the Dual-SPGE at 4ºC of 20 min; and, (iv) aptamer-protein interaction time of 30 min. The evaluation of the best experimental conditions was carried out by cyclic and square wave voltammetry using a ferro/ferricyanide solution ([Fe(CN)6]3−/4−) as a redox probe. Aptamers were immobilized onto the Dual-SPGE via streptavidin-biotin interaction. With the preliminary optimal experimental conditions herein obtained, we will further assess the sensitivity of the Dual-SPGE using synthetic plasma.