Development of an Impedimetric Aptasensor for Label Free Detection of Patulin in Apple Juice

Abstract

In the present work, an aptasensing platform was developed for the detection of a carcinogenic mycotoxin termed patulin (PAT) using a label-free approach. The detection was mainly based on a specific interaction of an aptamer immobilized on carbon-based electrode. A long linear spacer of carboxy-amine polyethylene glycol chain (PEG) was chemically grafted on screen-printed carbon electrodes (SPCEs) via diazonium salt in the aptasensor design. The NH2-modified aptamer was then attached covalently to carboxylic acid groups of previously immobilized bifunctional PEG to build a diblock macromolecule. The immobilized diblocked molecules resulted in the formation of long tunnels on a carbon interface, while the aptamer was assumed as the gate of these tunnels. Upon target analyte binding, the gates were assumed to be closed due to conformational changes in the structure of the aptamer, increasing the resistance to the charge transfer. This increase in resistance was measured by electrochemical impedance spectroscopy, the main analytical technique for the quantitative detection of PAT. Encouragingly, a good linear range between 1 and 25 ng was obtained. The limit of detection and limit of quantification was 2.8 ng L−1 and 4.0 ng L−1, respectively. Selectivity of the aptasensor was confirmed with mycotoxins commonly occurring in food. The developed apta-assay was also applied to a real sample, i.e., fresh apple juice spiked with PAT, and toxin recovery up to 99% was observed. The results obtained validated the suitability and selectivity of the developed apta-assay for the identification and quantification of PAT in real food samples.

Flexible Screen Printed Aptasensor for Rapid Detection of Furaneol: A Comparison of CNTs and AgNPs Effect on Aptasensor Performance

“…For CNT-ME, after CNTs deposition, the peak current was increased (I p = 15.02 mA) due to the increased electroactive area and to the good conductivity of the CNTs, which promoted the electron transfer between the electrolyte and the electrode [ 14 ]. Furthermore, the immobilization of the aptamers onto the CNTs led to a dramatic decrease (I p = 4.92 mA) in the redox current peak, which is in agreement with previous work [ 36 , 37 ]. This may be due to the DNA backbone, which is composed of phosphate groups and sugars.…”

“…This may be due to the DNA backbone, which is composed of phosphate groups and sugars. The phosphate groups are negatively charged, which makes the aptamers negatively charged; thus, the immobilized aptamers repel the [Fe (CN) 6 ] 3–/4– anions from the electrode surface and also acts as a barrier for electron transfer [ 37 ]. After incubation of the CNT-ME/aptamer with cDNA, the redox current peak was slightly increased (I p = 10.94 mA), which may be due to the hybridization that makes the negatively charged Aptamer-MB distant from the electrode surface, hence increasing electron transfer near the electrode surface [ 38 ].…”

“…for instance, the difference in the number of aptamers immobilized on WE between one aptasensor and another may decrease the sensitivity. However, by subtracting the current generated from the blank sample, in this way, only the current generated because of the analyte will be measured, no matter the amount of the aptamers immobilized on the WE [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 ]. Hence, we increase the reproducibility of the aptasensors.…”

Carbon and Tin-Based Polyacrylonitrile Hybrid Architecture Solid Phase Microextraction Fiber for the Detection and Quantification of Antibiotic Compounds in Aqueous Environmental Systems

“…The calculated signal to noise ratios of 3 (S/N = 3) and 10 (S/N = 10) signify the limit of detection (LOD) and limit of quantification (LOQ), respectively [54]. The relative standard deviation (RSD) for the intra-fiber reproducibility ( n = 6) of six sampling-desorption cycles ranged from 1.8% to 6.8%, indicating satisfactory stability for repeated use of the custom-made fiber.…”

MXenes-Based Bioanalytical Sensors: Design, Characterization, and Applications

“…Biosensors with nucleic acid detection using either optical or electrical output to monitor the hybridization event have been widely reported as bioanalytical platforms for many applications [ 87 ]. Recently, MXenes have been explored as an electrode material to monitor the hybridization event and enhance detection sensitivity.…”