Glucose Oxidase-Functionalized Nanodiamond Films for Biosensor Application
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Glucose Oxidase-Functionalized Nanodiamond Films for Biosensor Application Pedro Villalba3,4, Manoj K. Ram1, 2, Humberto Gomez1,4, Amrita Kumar5 Venkat Bhethanabotla3 and Ashok Kumar1, 2 1 Department of Mechanical Engineering, University of South Florida, 4202 E Fowler Avenue, Tampa, FL, 33620-5350. 2 Nanotechnology Research and Education Center (NREC), University of South Florida. 3 Department of Chemical and Biomedical Engineering, University of South Florida. 4 Departamento de Medicina. Universidad del Norte. Km 5 Via Puerto Colombia, Barranquilla, Colombia. 5 Center for Cell and Molecular Signaling, Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322. ABSTRACT The importance of nanodiamond in biological and technological applications has been recognized, and applied in drug delivery, biochip, sensors and biosensors. Nanodiamond (ND) and nitrogen doped nanodiamond (NND) films were deposited on n-type silicon films, and later functionalized with enzyme glucose oxidase (GOX). Functionalized electrode has been characterized using different techniques; i.e.fourier transform spectroscopy (FTIR) -, Raman spectroscopy, atomic force microscopy (AFM) and electrochemical techniques, respectively. Under this work, the ND/GOX and NND/GOX electrodes have demonstrated providing sensitive glucose concentration response. Besides, the cytotoxic effects of the NDs have been studied in vitro. Human Embryonic Kidney 293 (HEK293) cells are cultured in the presence of the films then toxicity has been detected using MTT-based cytotoxicity assays utilizing 3-(4, 5-Dimethyl2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide (MTT). The final results for MTT assays are quantified by spectrophotometry using a plate reader at 570 nm As-prepared nanodiamond has been found to be stable , biocompatible and useful for biosensing applications. A linear response of the enzyme based electrode to glucose concentration is also observed from 1-8 x mM before saturation condition close to 10mM has been observed. INTRODUCTION Nanodiamond (ND) possesses a unique combination of properties i.e., mechanical stability, chemical inertness and biocompatibility makeing it highly suitable for applications in medicine and biosensors [1, 2]. ND has also provided a unique platform for bio-conjugation with DNA, metalloprotein, antigens, and enzyme molecules [3-6]. Due to the mechanical, electrical, and electrochemical properties of nanodiamond film, the possibility to operate in a chemically harsh environment is favored as a promising alternative transducer material for chemical and biological sensing material [7]. Recently, enzyme-modified diamond sensors have been realized for the detection of urea and pH of the solutions [1]. Besides, the highly pH-sensitive properties of O-terminated NDs have been used to develop EDIS penicillin sensor application [8]. The higher surface area-to-volume ratio of ND and the delicate balance of sp2–sp3 inherent in these composites allowing to generate a highly active electrode material. [9]. The high stren
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