Immobilization of Tyrosinase in Nanocrystalline Cellulose/Chitosan Composite Film for Amperometric Detection of Phenol

Abstract

Nanocrystalline cellulose (NCC)/chitosan composite for immobilization of tyrosinase enzyme for the determination of phenol have been developed. The NCC/Chitosan composite film on screen printed carbon electrode (SPCE) was prepared by using drop casting technique. Characterization of the modified SPCE surface was investigated by using Transmission Electron Microscopy (TEM) and Fourier Transform Infrared (FTIR), respectively. Chronoamperometric (CA) technique is used to perform the electrochemical measurements. The detection of phenols by the developed system is derived on the direct electrochemical reduction of quinones produced by enzymatic reaction. The results demonstrated that the maximum response was observed at ratio of NCC/chitosan of 1 to 1 (v/v), tyrosinase concentration of 10 mg/mL and pH buffer of 7, respectively. It was found that the developed system gave linear response in the phenol concentration range of 0.39 -7.74 µM (slope = 28.316, R 2 = 0.9808) with the detection limit of 0.38 µM. The reproducibility of the system was also estimated and the Relative Standard Deviation (RSD) was found to be at 4.27%. Keywords: nanocrystalline cellulose, nanocomposite, immobilization, electrochemical, phenol AbstrakKomposit selulosa nanokristalin/kitosan untuk pemegunan enzim tirosinase bagi penentuan fenol telah dibangunkan. Filem komposit NCC/Chitosan di atas elektod karbon skrin bercetak (SPCE) telah disediakan melalui kaedah penyalutan acuan. Pencirian permukaan SPCE dimodifikasi dikaji menggunakan Mikroskop Elektron Transmisi (TEM) dan Transformasi Fourier Inframerah (FTIR). Teknik kronoamperometri (CA) digunakan untuk menjalankan pengukuran elektrokimia. Pengesanan fenol oleh sistem yang dibangunkan ini adalah berasaskan penurunan langsung elektrokimia oleh kuinon yang dihasilkan daripada tindak balas enzim. Keputusan menunjukkan bahawa rangsangan maksimum diperhatikan pada nisbah NCC/kitosan adalah 1 kepada 1 (v/v), kepekatan tirosinase 10 mg/mL dan larutan penimbal pada pH 7. Didapati bahawa sistem yang dibangunkan memberi rangsangan linear dalam julat kepekatan fenol 0.39-7.74 µM (kecerunan = 28.316, R 2 = 0.9808) dengan had pengesanan 0.38 µM. Kebolehulangan sistem juga telah dianggarkan dan nilai sisihan piawai relatif (RSD) yang diperolehi ialah 4.27%.Kata kunci: selulosa nanokristalin, nanokomposit, pemegunan, elektrokimia, fenol ISSN -2506 Fariza Aina et al: IMMOBILIZATION OF TYROSINASE IN NANOCRYSTALLINE CELLULOSE/CHITOSAN COMPOSITE FILM FOR AMPEROMETRIC DETECTION OF PHENOL 979Introduction Nanocrystalline cellulose (NCC) is a unique and sustainable nanomaterial obtained through acid hydrolysis of native cellulose, it has remarkable physical properties, such as biocompatibility, biodegradability and low toxicity as it originating from natural resources raw materials [1]. NCC has been studied to have a rigid rod-shape structure with 5 -10 nm in diameter and 10 -100 nm in length [2]. It can be extracted from native cellulose which is found in plants, animals and bacteria that composed of the ...