Contents lists available at ScienceDirect Talanta journal homepage: www.elsevier.com/locate/talanta Screen printed electrode-based biosensor functionalized with magnetic cobalt/single-chain antibody fragments for cocaine biosensing in different matrices Serdar Sanli a,1 , Hichem Moulahoum a,∗,1 , Ozge Ugurlu a , Faezeh Ghorbanizamani a , Zinar Pinar Gumus b , Serap Evran a , Hakan Coskunol c , Suna Timur a,b,∗∗ a Department of Biochemistry, Faculty of Science, Ege University, 35100, Bornova, Izmir, Turkey b Central Research Test and Analysis Laboratory Application and Research Center, Ege University, 35100, Bornova, Izmir, Turkey c Faculty of Medicine, Ege University, 35100, Bornova, Izmir, Turkey ARTICLEINFO Keywords: Biosensor Cobalt oxide particle Single-chain Fv antibody Substance abuse Cocaine ABSTRACT On-site detection of substance abuse is an important approach in the preventive and intervention protocols implementations. It is known that the traditional methods are heavy, time-consuming, and need a high level of logistical requirements. As such, biosensors represent great potential to simplify and improve substance abuse detection. In this study, we have designed a functionalized screen-printed electrode (SPE) electrochemical biosensor with cobalt oxide nanoparticles and single-chain antibody fragments (scFvs) for cocaine detection. Different electrochemical techniques such as differential pulse voltammetry, cyclic voltammetry, and electro- chemical impedance spectrometry were used to examine the functionality of the designed biosensor. Furthermore, SEM observations were performed to observe the surface changes after functionalization. The resultsshowedthatthelinearityrangedbetween5.0and250ng/mLandadetectionlimitof3.6ng/mL(n=6). These results were compared to results obtained from Q-TOF/MS where four different matrices (serum, sweat, urine, and saliva) were spiked with 100 ng/mL cocaine and were analyzed by both methods (Biosensor and Q- TOF/MS). Results showed a higher performance of the biosensor compared to traditional methods. In addition, the selectivity of the biosensor was shown in the presence of different interferents where the designed platform showed a specific response to only cocaine. In conclusion, the designed biosensor proposes great potential for portableandon-sitesubstanceabusedetectioninadditiontoboastingthecapabilityofreuseoftheSPEandthus, reducing the costs related to such applications. 1. Introduction On-site detection of cocaine has been attracting a lot of interest in recent years due to the severity of cocaine abuse in society [1]. The current procedures for cocaine abuse detection and quantification in samples are mostly performed using heavy instruments such as gas or liquid chromatography followed by mass spectrometry (GC-MS and LC- MS/MS) [2]. These approaches are time-consuming, show a necessity for plenty of pretreatment procedures, costly, and needs highly trained staff members to perform. Although the cocaine limit of detection (LOD) is quite satisfying, a need for more advantageous tools having faster, easy to operate, and portability features are necessary for dif- ferent fields of science and biomedicine [1]. Recently,biosensorsbecameafocusforscientistsfortheirflexibility to detect a myriad of target molecules, pathogens, and bacteria [3–5]. From the many possibilities, metallic nanoparticles represent a good candidate given their potential in enhancing the surface area, im- proving electron transfer, and the sensitivity of sensors [6–10]. Cobalt oxide nanoparticles are one of the metallic nanoparticles receiving the focus of many researchers due to many advantages seen. Cobalt oxide nanoparticles are known for their biocompatibility, stability, con- ductivity and electrocatalytic features. In addition, it is eco-friendly, easy to access, and of low cost [6,11–16]. In order to increase the biocompatibility and functional behavior of the nanoparticles, various materials are used for their functionalization (ie. polymers, antibodies, etc.) [17]. Thus, broadening the application https://doi.org/10.1016/j.talanta.2020.121111 Received 24 February 2020; Received in revised form 28 April 2020; Accepted 30 April 2020 ∗ Corresponding author. Ege University, Faculty of Science, Biochemistry Department, Bornova, 35100, Izmir, Turkey. ∗∗ Corresponding author. Central Research Test and Analysis Laboratory Application and Research Center, Ege University, 35100, Bornova, Izmir, Turkey. E-mail addresses: hic_moul@hotmail.com (H. Moulahoum), suna.timur@ege.edu.tr (S. Timur). 1 both authors contributed equally. Talanta 217 (2020) 121111 Available online 01 May 2020 0039-9140/ © 2020 Elsevier B.V. All rights reserved. T