title: Ultra trace analysis of small molecule by label-free impedimetric immunosensor using multilayer modified electrode.
abstract: A multilayer electrode modified with a self-assembled thiourea monolayer (SATUM) followed by gold nanoparticles (AuNPs), mercaptosuccinic acid (MSA) and antibody was investigated for the detection of ultra trace amount of a small molecule (chloramphenicol) in an impedimetric system. The formation of the antibody-antigen complex at the electrode surface caused the impedance to increase. Under optimum conditions three modified electrodes were compared the SATUM/AuNPs/MSA electrode provided a wide linear range (0.50-10) × 10⁻¹⁶ M, and a very low determination limit of 1.0 × 10⁻¹⁶ M. This determination limit was much lower than the SATUM/AuNPs electrode, 1.0 × 10⁻¹⁵ M, and SATUM electrode, 4.7 × 10⁻¹⁴ M. The modified electrode provided good selectivity for chloramphenicol detection and can be reused up to 45 times with a relative standard deviation of lower than 4%. When applied to determine chloramphenicol in shrimp samples, the results agreed well with those obtained by the high-performance liquid chromatography coupled with a photo diode array detector (P > 0.05). The developed system can be applied to detect other small molecules using appropriate affinity binding pairs.
authors.affiliation: Trace Analysis and Biosensor Research Center, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand.
authors.forename: Kochaporn
authors.initials: K
authors.lastname: Chullasat
authors.forename: Proespichaya
authors.initials: P
authors.lastname: Kanatharana
authors.forename: Warakorn
authors.initials: W
authors.lastname: Limbut
authors.forename: Apon
authors.initials: A
authors.lastname: Numnuam
authors.forename: Panote
authors.initials: P
authors.lastname: Thavarungkul
mesh_terms: D000818:Animals; D055910:Antibodies, Immobilized; D015374:Biosensing Techniques / Q000379:methods* / Q000706:statistics & numerical data; D002701:Chloramphenicol / Q000032:analysis / Q000276:immunology; D002851:Chromatography, High Pressure Liquid; D017097:Electric Impedance; D055664:Electrochemical Techniques; D004566:Electrodes; D017022:Flow Injection Analysis; D005506:Food Contamination / Q000032:analysis; D006046:Gold; D057230:Limit of Detection; D053768:Metal Nanoparticles; D015203:Reproducibility of Results; D012758:Shellfish / Q000032:analysis; D013870:Thiomalates; D013890:Thiourea
chemical_list: D055910:Antibodies, Immobilized; D013870:Thiomalates; D002701:Chloramphenicol; D006046:Gold; C046062:2-thiomalic acid; D013890:Thiourea