Utilizing a Sensitive Micro-balance (QCM) for Assessing the Antioxidant Response of Date Kernel Activated Carbon Nanomaterials Against Free Radicals

In this research, a relatively simple and inexpensive, real-time and high-resolution mass sensing technique is proposed for the first time in order to evaluate radical scavenging capacity of the activated carbon (AC) nanomaterials produced from the natural and low-cost date kernels. For this purpose, a type of the mass sensitive resonant chemical micro-sensors namely quartz crystal microbalance (QCM) as a novel potential tool was developed. In this technique, the frequency changes resulting from the mass changes due to adsorption of the free radicals are measured using the quartz crystal surface modified by the cysteine. In order to characterize the surface structure, size and morphology of synthesized AC nanomaterials, the FT-IR, XRD, FE-SEM and TEM analyses were used. The antiradical/antioxidant ability of the AC nanomaterials was measured against the TEMPO and DPPH radicals in concentrations of 10 to 50 ppm at the room temperature and then compared with antioxidant capacity of the vitamin C as the reference antioxidant. Finally, the adsorption behavior of the radicals onto the QCM crystal's modified surface was analyzed based on Langmuir and Freundlich equations and the Langmuir model was found to best-fit the adsorption data. The obtained results indicated that date kernel AC nanomaterials can be used as effective and low-cost scavengers against TEMPO and especially DPPH free radicals.