Direct detection of OTA by impedimetric aptasensor based on modified polypyrrole-dendrimers.
Ochratoxin A (OTA) is a carcinogenic mycotoxin that contaminates food such as cereals, wine and beer; therefore it represents a risk for human health. Consequently, the allowed concentration of OTA in food is regulated by governmental organizations and its detection is of major agronomical interest. In the current study we report the development of an electrochemical aptasensor able to directly detect trace OTA without any amplification procedure. This aptasensor was constructed by coating the surface of a gold electrode with a film layer of modified polypyrrole (PPy), which was thereafter covalently bound to polyamidoamine dendrimers of the fourth generation (PAMAM G4). Finally, DNA aptamers that specifically binds OTA were covalently bound to the PAMAM G4 providing the aptasensor, which was characterized by using both Atomic Force Microscopy (AFM) and Surface Plasmon Resonance (SPR) techniques. The study of OTA detection by the constructed electrochemical aptasensor was performed using Electrochemical Impedance Spectroscopy (EIS) and revealed that the presence of OTA led to the modification of the electrical properties of the PPy layer. These modifications could be assigned to conformational changes in the folding of the aptamers upon specific binding of OTA. The aptasensor had a dynamic range of up to 5 μg L(-1) of OTA and a detection limit of 2 ng L(-1) of OTA, which is below the OTA concentration allowed in food by the European regulations. The efficient detection of OTA by this electrochemical aptasensor provides an unforeseen platform that could be used for the detection of various small molecules through specific aptamer association.
ICMMO, CNRS, Université Paris-Saclay, Equipe de Chimie Bio-organique et Bio-inorganique, Bâtiment 420, 91405 Orsay, France; BAE, Université de Perpignan, 52 Avenue Paul Alduy, 66860 Perpignan, France; Université de Carthage, National Institute of Applied Sciences and Technology (INSAT) Laboratoire d'Ecologie et de Technologie Microbiennes (LETMi), 1080 Tunis, Tunisia.
Nawel
N
Mejri-Omrani
ICMMO, CNRS, Université Paris-Saclay, Equipe de Chimie Bio-organique et Bio-inorganique, Bâtiment 420, 91405 Orsay, France.
Anna
A
Miodek
ICMMO, CNRS, Université Paris-Saclay, Equipe de Chimie Bio-organique et Bio-inorganique, Bâtiment 420, 91405 Orsay, France.
Becem
B
Zribi
Université de Carthage, National Institute of Applied Sciences and Technology (INSAT) Laboratoire d'Ecologie et de Technologie Microbiennes (LETMi), 1080 Tunis, Tunisia; Université de Tunis El Manar, Higher Institute of Applied Biological Sciences (ISSBAT), 1006 Tunis, Tunisia.
Mouna
M
Marrakchi
Université de Carthage, National Institute of Applied Sciences and Technology (INSAT) Laboratoire d'Ecologie et de Technologie Microbiennes (LETMi), 1080 Tunis, Tunisia.
Moktar
M
Hamdi
BAE, Université de Perpignan, 52 Avenue Paul Alduy, 66860 Perpignan, France.
Jean-Louis
JL
Marty
ICMMO, CNRS, Université Paris-Saclay, Equipe de Chimie Bio-organique et Bio-inorganique, Bâtiment 420, 91405 Orsay, France. Electronic address: hafsa.korri-youssoufi@u-psud.fr.
Hafsa
H
Korri-Youssoufi
D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D002273:Carcinogens / Q000032:analysis*; D050091:Dendrimers / Q000737:chemistry*; D058266:Dielectric Spectroscopy / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D005504:Food Analysis / Q000295:instrumentation / Q000379:methods; D006801:Humans; D057230:Limit of Detection; D008958:Models, Molecular; D009757:Nylons / Q000737:chemistry*; D009793:Ochratoxins / Q000032:analysis*; D011108:Polymers / Q000737:chemistry*; D011758:Pyrroles / Q000737:chemistry*; D014920:Wine / Q000032:analysis*
D052157:Aptamers, Nucleotide; D002273:Carcinogens; D050091:Dendrimers; D009757:Nylons; D009793:Ochratoxins; C520550:PAMAM-G4; D011108:Polymers; D011758:Pyrroles; C025589:ochratoxin A; C067635:polypyrrole
Aptasensor; Impedance; Ochratoxin A; PAMAM; Polypyrrole; Wine