Cu-In-S/ZnS quantum dots/silver nanoparticles nanocomposites-modified electrode as an electrochemical label-free aptasensor for the detection of β-casomorphin 7 in early distinguish of autism

Abstract

In this study, the efficiency of a nanocomposite contains the quantum dots and silver nanoparticle (AgNP/QDs) has been investigated to modify a glassy carbon electrode (GCE) in the aptasensor construction. Accordingly, the modified GCE provides a sub-layer to load more aptamers (Apts) through a linker agent of the AgNP to identify the β-casomorphin 7 (BCM-7) as an autism biomarker. The Apt/target interaction on the sensing interface surface leads to an electron transfer hindrance of the Rutin (RU) as a green redox probe. Consequently, a corresponding decrease in the current signal of the RU is achieved. The electrochemical studies show that the obtained signal responses linearly correlate with various BCM-7 concentrations in two ranges of 1 pM-20 nM and 20 nM-1.3 µM with a calculated limit of detection (LOD) 332 fM. The label-free aptasensor presents a high selectivity towards the BCM-7 in the presence of several similar amino acids. The analysis of the human urine and blood samples demonstrates the sufficient capability of the aptasensor in the BCM-7 detection in the real samples.