Preparation and characterization gallic acid-titanium dioxide nanocomposites for biosensing application on voltammetric detection of DNA

The preparation and testing of Chitosan-[Gallic Acid-Titanium Dioxide] (CHIT-[GA-TiO2]) modified single-use electrodes was performed herein. TiO2 nanoparticles were firstly synthesized by alkoxide hydrolysis and solvothermal method. [GA-TiO2] samples were prepared by using gallic acid and TiO2 nanoparticles while being dissolved in chitosan solution. Crystalline structure and surface properties of the obtained Chitosan[Gallic Acid-Titanium Dioxide] (CHIT-[GA-TiO2]) nanocomposite were characterized by using X-ray diffraction analysis and scanning electron microscopy (SEM). The CHIT-[GA-TiO2] modified single-use electrodes were developed for the first time in our present study and applied for electrochemical monitoring of nucleic acid interaction. For this purpose, the modification of nanocomposite was examined using pencil graphite electrodes (PGEs) in combination with differential pulse voltammetry (DPV), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. After fsDNA was immobilized onto the surface of CHIT[GA-TiO2]/PGE, fsDNA concentration and immobilization time were optimized as 30 mu g/mL and 15 min, respectively. The detection limit was calculated and found to be 0.95 mu g/mL in the linear concentration range of fsDNA from 2 to 10 mu g/mL with the sensitivity of 1.161 mu A mL cm-2 mu g-1.