title: Polyaniline Langmuir-Blodgett film based aptasensor for ochratoxin A detection.
abstract: Ochratoxin A (OTA) produced by Aspergillus Ochraceus and Penicillium verrucosum is a very dangerous toxin due to its toxic effects in human beings and its presence in a wide range of food products and cereals. A Langmuir-Blodgett (polyaniline (PANI)-stearic acid (SA)) film based highly sensitive and robust impedimetric aptasensor has been developed for ochratoxin A (OTA) detection. DNA Aptamer (Apt-DNA) specific to OTA has been covalently immobilized onto mixed Langmuir-Blodgett (LB) monolayer comprising of PANI-SA deposited onto indium tin-oxide (ITO) coated glass plates. This Apt-DNA/PANI-SA/ITO aptaelectrode has been characterized using scanning electron microscopy, Fourier transform-infrared spectroscopy, contact angle measurements, cyclic voltammetry and electrochemical impedance spectroscopy, respectively. The Apt-DNA/PANI-SA/ITO aptasensor shows detection of OTA by electrochemical impedance spectroscopy in the linear range of 0.0001 μg/ml (0.1 ng/ml) to 0.01 μg/ml (10 ng/ml) and 1 μg/ml-25 μg/ml with detection limit of 0.1 ng/ml in 15 min. The Apt-DNA/PANI-SA/ITO aptasensor can be reused ∼13 times. The binding or affinity constant (K(a)) of aptamer with OTA, calculated using Langmuir adsorption isotherm, is found be 1.21×10(7) M(-1).
authors.affiliation: Department of Science and Technology Centre on Biomolecular Electronics, Biomedical Instrumentation Section, Materials Physics & Engineering Division, National Physical Laboratory (Council of Scientific & Industrial Research), Dr. K. S. Krishnan Marg, New Delhi 110012, India.
authors.forename: Nirmal
authors.initials: N
authors.lastname: Prabhakar
authors.forename: Zimple
authors.initials: Z
authors.lastname: Matharu
authors.forename: B D
authors.initials: BD
authors.lastname: Malhotra
mesh_terms: D000814:Aniline Compounds; D052157:Aptamers, Nucleotide; D015374:Biosensing Techniques / Q000379:methods*; D058266:Dielectric Spectroscopy; D055664:Electrochemical Techniques; D005506:Food Contamination / Q000032:analysis; D006801:Humans; D008855:Microscopy, Electron, Scanning; D009793:Ochratoxins / Q000032:analysis*; D017550:Spectroscopy, Fourier Transform Infrared; D013229:Stearic Acids; D017971:Tin Compounds
chemical_list: D000814:Aniline Compounds; D052157:Aptamers, Nucleotide; D009793:Ochratoxins; D013229:Stearic Acids; D017971:Tin Compounds; C416807:polyaniline; C025589:ochratoxin A; C031183:stearic acid; C109984:indium tin oxide