Electrochemiluminescence methods using CdS quantum dots in aptamer-based thrombin biosensors: a comparative study

Abstract

The detection of thrombin by using CdS nanocrystals (CdS NCs), gold nanoparticles (AuNPs) and luminol is investigated in this work. Thrombin is detected by three methods. One is called the quenching method. It is based on the quenching effect of AuNPs on the yellow fluorescence of CdS NCs (with excitation/emission wavelengths of 355/550 nm) when placed adjacent to CdS NCs. The second method (called amplification method) is based on an amplification mechanism in which the plasmonics on the AuNPs enhance the emission of CdS NCs through distance related Förster resonance energy transfer (FRET). The third method is ratiometric and based on the emission by two luminophores, viz. CdS NCs and luminol. In this method, by increasing the concentration of thrombin, the intensity of CdS NCs decreases, while that of luminol increases. The results showed that ratiometric method was most sensitive (with an LOD of 500 fg.mL-1), followed by the amplification method (6.5 pg.mL-1) and the quenching method (92 pg.mL-1). Hence, the latter is less useful.

Flow Injection Analysis-Based Electrochemiluminescence: An Overview of Experimental Design and Its Biosensing Applications

“…Nanomaterials such as quantum dots (QDs), metal clusters are frequently used as ECL reagents. 18,[41][42][43][44] Metal based QDs like cadmium selenide (CdSe), [45][46][47] cadmium sulfide (CdS), 48,49 cadmium telluride (CdTe), 41,46,48 CdSe/zink sulfide (ZnS), 46,47 and CdZnSe, 46 and carbon-based QDs such as carbon QDs (CQDs) 50 and graphene QDs (GQDs) 47,51,52 are the mostly used nanomaterials as luminophores. One of the major advantages of these nanomaterials is they can easily make covalent linkage with other molecules z E-mail: pgraju146@gmail.com; ssenthilmugam@gmail.com; ssenthilkumar@cecri.…”

“…53 Also, N, N-diethylethylenediamine (DEDA) linked with gold nanoclusters shows strong ECL signal in blank electrolytic solution. 54 Moreover, ECL can be utilized for the detection of small molecules like DNA, 55 immunoassays, 56,57 aptamers, 49,58,59 cancer cells, 60 pollutants and metal ions. 12 The conventional ECL can be further modified to develop commercialized devices for biosensor applications.…”

Recent Advances in Nanomaterial-Based Aptasensors in Medical Diagnosis and Therapy

“…The aptasensor was capable of detecting cardiac troponin 1, a biomarker for acute myocardial infarction, with an LOD of 0.75 fg/mL and they further observed that the signal of the surface plasmon enhanced electrochemiluminescence (SPEECL) aptasensor was five-fold higher with AuNPs as the ECL plasmon source. Isildak et al [ 41 ] also investigated detection of thrombin by an ECL aptasensor. When CdS nanocrystals (CdS NCs) and luminol were conjugated with aptamer/AuNPs, detection of thrombin was based on ratiometric ECL and increase in thrombin concentration led to a decrease in intensity (quenching) of CdS NCs with concomitant increase in luminol intensity.…”

An Electrochemiluminescence Biosensor for the Detection of Alzheimer’s Tau Protein Based on Gold Nanostar Decorated Carbon Nitride Nanosheets

“…Electrochemiluminescence (ECL), also called electrogenerated chemiluminescence, converts the input electrical signal into optical readout, which is different from most other electrochemical methods [8,9]. In fact, ECL relies on the generation of luminophore in the vicinity of the electrode surface by applying voltage.…”