Malaysian Journal of Analytical Sciences, Vol 21 No 3 (2017): 518 - 526 DOI: https://doi.org/10.17576/mjas-2017-2103-01 518 MALAYSIAN JOURNAL OF ANALYTICAL SCIENCES Published by The Malaysian Analytical Sciences Society ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA)-BASED-SENSOR FOR DETERMINATION OF BENZO[A]PYRENE IN RIVER WATER USING SCREEN-PRINTED GOLD ELECTRODE (Sensor-berasaskan Ujian Enzim-Pengerap Immuno (ELISA) untuk Pengesanan Benzo[a]pirina dalam Air Sungai Menggunakan Elektrod Emas Skrin Tercetak) Noor Sheryna Jusoh, Alyza Azzura Abd Rahman Azmi, Azrilawani Ahmad* School of Marine and Environmental Sciences, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, Malaysia *Corresponding author: azrilawani.ahmad@umt.edu.my Received: 16 August 2016; Accepted: 15 April 2017 Abstract This paper described the surface modification of screen-printed gold electrode using thiol self-assembled monolayer, in combination with enzyme-linked immunosorbent assay (ELISA) format for determination of benzo[a]pyrene (BaP) in water sample. All biomolecules were immobilized on the surface of working electrode to increase the sensitivity of the developed biosensor by applying different types of ELISA. Electrochemical characterizations using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were carried out to study the conductivity behavior of the developed biosensor. Based on the results, biomolecules were successfully immobilized and characterized optically and electrochemically. Optical immunoassay with indirect competitive ELISA were developed for the determination of BaP compound which showed the best performance compared to other assay. In optical measurement, normal assay exhibits higher absorbance, implying high bio complex formation. Modification of electrode using 11-MUA was successful due to highest blocking effect for electron transfer process. Determination of BaP in real water samples shows that there no BaP was detected in all samples collected, due to no presence of BaP in all samples. Keywords: surface modification, screen-printed gold electrode, benzo[a]pyrene, water sample Abstrak Kertas kerja ini menerangkan pengubahsuaian permukaan elektrod emas skrin tercetak menggunakan lapisan mono tepasang menggunakan tiol, dengan kombinasi format ujian enzim-pengerap imuno (ELISA) untuk penentuan benzo[a]pirina (BaP) dalam sampel air. Semua molekul bio telah dipegunkan di atas permukaan elektrod bekerja untuk meningkatkan kepekaan biosensor yang dibangunkan dengan menggunakan pelbagai jenis ELISA. Pencirian elektrokimia menggunakan voltametri kitaran (CV) dan spektroskopi impedans elektrokimia (EIS) telah dilakukan untuk mengkaji tingkah laku kekonduksian biosensor yang dibangunkan. Berdasarkan keputusan yang diperolehi, molekul bio telah berjaya dipegunkan dan dicirikan secara optik dan elektrokimia. Ujian imuno optik dengan ELISA bersaing secara tak langsung telah dibangunkan untuk penentuan sebatian BaP menunjukkan prestasi terbaik berbanding ujian lain. Dalam pengukuran optik, ujian normal mempamerkan keserapan lebih tinggi, menandakan pembentukan kompleks bio yang tinggi. Pengubahsuaian elektrod menggunakan 11-MUA berjaya disebabkan oleh kesan halangan tertinggi bagi proses pemindahan elektron. Penentuan BaP dalam sampel air sebenar menunjukkan tiada BaP dikesan dalam semua sampel yang diambil, kerana ketiadaan BaP dalam semua sampel. Kata kunci: pengubahsuaian permukaan, elektrod emas skrin tercetak, benzo[a]pirina, sampel air ISSN 1394 - 2506