In this PhD thesis, the work is organised into separate articles that have been published. In the first part of the thesis, the electrocatalytic properties of o-aminophenol films grafted on glassy carbon surfaces have been employed for the electrochemical evaluation of hydrazine, NADH and ascorbic acid (AA). AA system was explored for clinical and food applications such as the determination of uric acid in presence of AA, and the detection of AA in real samples of fruits and vegetables using disposable screen printed electrodes. In the second part of the thesis, different surface engineering...