Design and engineering of quantum dot-based biosensor for detection of cardiac biomarkers

Abstract

Introduction: The synthesis of semiconductor nanocrystals is of great interest due to their outstanding optical and electrical properties. Among the various applications of nanocrystals (NCs), they have been considered for the diagnosis and treatment of the disease. In this regard they have been used for the development of various types of biosensors. Goals: Here, a facile, reproducible and one-pot synthesis of high-quality and monodispersed CdS semiconducting nanocrystals is provided. The practical efficiency of the synthesized NCs was proved through applying them as tracer in the fabrication of an immunosandwich type biosensor for evaluation of cardiac troponin (cTn) marker for diagnosis and monitoring of myocardial infarction. The synthesized CdS nanocrystals were used as tracer in conjugation with detection antibodies. Methods: CdS nanocrystals’ synthesis were carried out by mixing precursors cadmium acetate and elemental sulfur into the new solvent system of dibenzyl ether and oleylamine without using any extra reagent or precursor activator. An immune-sandwich biosensor, similar to what happens in ELISA, was developed to detect cardiac troponin. The biosensor uses an electrochemical detector in which cadmium sulfide nanocrystals are involved in generating electrochemical signals. Results and discussion: The obtained NCs exhibited a dominant band-edge emission with a suitable photoluminescence quantum yield of 13.76 % without trap emission. The size of 5 nm was achieved for resulting NCs as shown by transmission electron microscope (TEM). Although the size of NCs was evaluated by other optical and computational methods which have a high agreement with together. The constructed biosensor revealed superb analytical efficiency with a limit of detection 2 ng L-1 and a linear dynamic range of 5-1000 ng L-1 which is lower than the existing recommended cutoff level (13-20 ng L-1).