Full Length Article Tyrosinase immobilization on functionalized porous silicon surface for optical monitoring of pyrocatechol Kahina Lasmi a , Habiba Derder b , Amina Kermad a , Sabrina Sam a,⇑ , Hinda Boukhalfa-Abib b , Samia Belhousse a , Fatma Zohra Tighilt a , Khaled Hamdani a , Noureddine Gabouze a a Division Couches Minces Surfaces Interfaces (CMSI), Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Algiers, Algeria b Faculté des sciences biologiques, Université des sciences et Technologie Houari Boumediene (USTHB), Algiers, Algeria article info Article history: Received 14 October 2017 Revised 4 March 2018 Accepted 5 March 2018 Available online xxxx Keywords: Porous silicon Tyrosinase immobilization Enzymatic activity Functionalization Pyrocatechol detection abstract Immobilized Tyrosinase enzyme was widely investigated for developing sensitive and specific biosensors for determination of phenolic compounds. However, the performance and stability of these biosensors largely depend upon the used support material and method of enzyme immobilization. In this work, covalent and stable attachment of active Tyrosinase on porous silicon (PSi) support for the detection of phenolic derivatives was achieved. A multistep functionalization strategy was developed in mild conditions allowing the activity retention of the immobilized enzyme. The surface was characterized with contact angle measurements, SEM microscopy and FTIR spectroscopy. The results confirmed the attachment of Tyrosinase enzyme on the functionalized PSi surface. The enzymatic activity of immobi- lized Tyrosinase and the optical detection of pyrocatechol were studied basing on the assessment of the UV/Vis absorbance at 500 nm of a colored azo-dye product formed from the reaction of 3-methyl- 2-benothiazolinone hydrazone (MBTH) reagent with the Quinone issuing from the enzymatic oxidation of pyrocatechol. The surface concentration of active Tyrosinase was estimated to be C = 1.135  10 15 molecules covering the whole PSi surface. The calibration curve of pyrocatechol detection shows linearity over a wide concentration range (1–100 lM) with a correlation coefficient of 0.995 and a detection limit of 0.43 lM. These results show the efficiency of the Tyrosinase-modified PSi surface for phenol detection and the possibility to use the structure in real applications. Ó 2018 Elsevier B.V. All rights reserved. 1. Introduction Phenol and its derivatives are hazardous pollutants present in wastewater issuing from several industries comprising coal trans- formation, oil refining and synthesis of resins, plastics, dyes and paper [1]. Their high toxicity and their persistence is currently one of the major challenges for environmental chemistry. Several methods, namely gas chromatography, liquid chromatography and capillary electrophoresis have been developed for phenolic compounds detection [2]. However, these methods are expensive, time consuming, require samples pretreatment and may not be suitable for in situ monitoring. Therefore, there was an urgent need to develop new, fast and easy detection methods permitting the measurement of very low concentrations directly in the field. For this purpose, biosensors have been proposed by several research- ers as a potential alternative to traditional methods [3]. Biosensors are analytical devices which combine a bioselective component called ‘‘bioreceptor‘‘ and a ‘‘transducer” [4]. The biore- ceptor (enzymes, antibodies, nucleic acids,...) allows the molecular recognition and the transducer system transforms physicochemical changes induced in the sensitive layer into a measurable signal (electrical, optical, thermal,...). The most widespread biosensors are based on the use of enzymes responsible for detecting specific substrates and inhibitors. The choice of solid supports and immobilization strategies is the key challenge in enzymatic biochips in terms of sensitivity, stability, response time and reproducibility. The crucial point is the conservation of the biological activity of enzymes [5]. Tyrosi- nase based biosensors have received great interest, providing some specific advantages such as the ability to catalyze electron-transfer reactions without need of additional cofactors and oxidation of phenolic compounds in the presence of oxygen [6–7]. However, there are very few reports on Tyrosinase based optical biosensors compared to amperometric biosensors [8]. Moreover, though a variety of materials have been reported for Tyrosinase immobiliza- tion they suffer from disadvantages such as low operational and https://doi.org/10.1016/j.apsusc.2018.03.037 0169-4332/Ó 2018 Elsevier B.V. All rights reserved. ⇑ Corresponding author. E-mail address: samsabrina@crtse.dz (S. Sam). Applied Surface Science xxx (2018) xxx–xxx Contents lists available at ScienceDirect Applied Surface Science journal homepage: www.elsevier.com/locate/apsusc Please cite this article in press as: K. Lasmi et al., Tyrosinase immobilization on functionalized porous silicon surface for optical monitoring of pyrocatechol, Appl. Surf. Sci. (2018), https://doi.org/10.1016/j.apsusc.2018.03.037