Label-Free and Redox Markers-Based Electrochemical Aptasensors for Aflatoxin M1 Detection

Abstract

We performed a comparative analysis of the sensitivity of aptamer-based biosensors for detection mycotoxin aflatoxin M1 (AFM1) depending on the method of immobilization of DNA aptamers and method of the detection. Label-free electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) for ferrocene labeled neutravidin layers were used for this purpose. Amino-modified DNA aptamers have been immobilized at the surface of polyamidoamine dendrimers (PAMAM) of fourth generation (G4) or biotin-modified aptamers were immobilized at the neutravidin layer chemisorbed at gold surface. In the first case the limit of detection (LOD) has been determined as 8.47 ng/L. In the second approach the LOD was similar 8.62 ng/L, which is below of allowable limits of AFM1 in milk and milk products. The aptasensors were validated in a spiked milk samples with good recovery better than 78%. Comparative analysis of the sensitivity of immuno- and aptasensors was also performed and showed comparable sensitivity.

2‐[(4‐Aminobutyl)ferrocenylmethylidene]‐5,6‐dimethoxy‐1‐indanone derivatives: Synthesis, characterization, and investigation of electro‐optical properties

“…Since their discovery ferrocene (Fc) and its derivatives have been proved to be the excellent chemical reagents in organic and organometallic synthesis, electrochemistry, catalysts, and design of new chiral materials . Nowadays, they have wide applications, for example, medicine, electro‐optical devices, modified electrodes and capacitors, biosensors, and protective coating materials …”

“…Since their discovery ferrocene (Fc) and its derivatives have been proved to be the excellent chemical reagents in organic and organometallic synthesis, electrochemistry, catalysts, and design of new chiral materials. [1][2][3][4][5] Nowadays, they have wide applications, for example, medicine, [6,7] electro-optical devices, [8,9] modified electrodes and capacitors, [10,11] biosensors, [12,13] and protective coating materials. [14] Cyclic voltammetry (CV) is perhaps a more versatile electrochemical technique in modern analytical chemistry that can be used for characterizing electroactive compounds.…”

Determination of Au Film Thiolation and Silane Bonding Onto SiO2 Films Within the Frame of Biosensor Surface Functionalization – an Analysis of Best Practices and Techniques

“…HERE has been extensive research in the area of selfassembled monolayers (SAMs) within the frame of biosensor surface functionalization. [1][2][3] SAMs are twodimensional nanomaterials that form spontaneously on a variety of solid surfaces in a highly ordered fashion, through the process of self-assembly of their molecular components. [4][5][6][7] In particular SAM formation is one of the simplest approaches in achieving thermodynamically stable monolayers through strong chemisorption that is in contrast to Langmuir-Blodgett and other techniques that lead to physisorption and unstable mono or multilayer films.…”

“…[13] Currently some of the most widely used SAMs in biosensing are thiols on Au surfaces and alkylsilanes on oxides, due to their relatively straightforward preparation leading to densely packed monolayers. [16] Generally, both types of thiols (R-SH or -C-SH) [14,15] and silanes (R-Si(OH)3) are strong surface anchors leading to chemisorption with the former binding well to metals, such as Au, Ag, Pt and Cu, while the latter binding preferably to surfaces such as SiO2, indium tin oxide (ITO) and TiO2. It is noted that within molecular immobilization chemisorption does not necessarily entail the presence of a full covalent bond, but also refers to charge-transfer (CT) complexes.…”

Electrochemical Aptasensor with Layer‐by‐layer Deposited Polyaniline for Aflatoxin M1 Voltammetric Determination

“…Latest research showed successful application of aptamer based biosensors (called as aptasensors) for AFM1 determination using label‐free electrochemical impedance spectroscopy (EIS) . In these aptasensors, target interactions of specific aptamer and AFM1 resulted in the changes of the electrode interface detected by variation of the signals of redox probe (mostly ferricyanide ion).…”