title: Use of Fe₃O₄ Nanoparticles for Enhancement of Biosensor Response to the Herbicide 2,4-Dichlorophenoxyacetic Acid.
abstract: Magnetic nanoparticles of Fe₃O₄ were synthesized and characterized using transmission electron microscopy and X-ray diffraction. The Fe₃O₄ nanoparticles were found to have an average diameter of 5.48 ±1.37 nm. An electrochemical biosensor based on immobilized alkaline phosphatase (ALP) and Fe₃O₄ nanoparticles was studied. The amperometric biosensor was based on the reaction of ALP with the substrate ascorbic acid 2-phosphate (AA2P). The incorporation of the Fe₃O₄ nanoparticles together with ALP into a sol gel/chitosan biosensor membrane has led to the enhancement of the biosensor response, with an improved linear response range to the substrate AA2P (5-120 μM) and increased sensitivity. Using the inhibition property of the ALP, the biosensor was applied to the determination of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The use of Fe₃O₄ nanoparticles gives a two-fold improvement in the sensitivity towards 2,4-D, with a linear response range of 0.5-30 μgL-1. Exposure of the biosensor to other toxicants such as heavy metals demonstrated only slight interference from metals such as Hg2+, Cu2+, Ag2+and Pb2+. The biosensor was shown to be useful for the determination of the herbicide 2, 4-D because good recovery of 95-100 percent was obtained, even though the analysis was performed in water samples with a complex matrix. Furthermore, the results from the analysis of 2,4-D in water samples using the biosensor correlated well with a HPLC method.
authors.affiliation: School of Chemical Sciences and Food Technology, Faculty of Science and Technology, University Kebangsaan Malaysia, Bangi, 43000, Selangor, Malaysia. keeshyuan@yahoo.com.
authors.forename: Kee-Shyuan
authors.initials: KS
authors.lastname: Loh
authors.affiliation: School of Chemical Sciences and Food Technology, Faculty of Science and Technology, University Kebangsaan Malaysia, Bangi, 43000, Selangor, Malaysia. yhl1000@ukm.my.
authors.forename: Yook Heng
authors.initials: YH
authors.lastname: Lee
authors.affiliation: School of Chemical Sciences and Food Technology, Faculty of Science and Technology, University Kebangsaan Malaysia, Bangi, 43000, Selangor, Malaysia. andong@ukm.my.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Musa
authors.affiliation: Biotechnology Research Centre, Malaysian Agriculture Research & Development Institute (MARDI), P.O. BOX 12301, GPO Kuala Lumpur, Malaysia. salmahaa@mardi.gov.my.
authors.forename: Abdul Aziz
authors.initials: AA
authors.lastname: Salmah
authors.affiliation: Biotechnology Research Centre, Malaysian Agriculture Research & Development Institute (MARDI), P.O. BOX 12301, GPO Kuala Lumpur, Malaysia. zamri@mardi.gov.my.
authors.forename: Ishak
authors.initials: I
authors.lastname: Zamri
keywords: 2; 4- dichlorophenoxyacetic acid; Fe3O4 nanoparticles; Screen-printer biosensor; alkaline phosphatase