Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Chemical Engineering and Biotechnologies, University Politehnica of Bucharest, Gh. Polizu St. 1-7, 011061 Bucharest, Romania; Research Institute of the University of Bucharest-ICUB, Spl. Independentei 91-95, 0500957 Bucharest, Romania; Research & Development for Advanced Biotechnologies and Medical Devices, SC Sanimed International Impex SRL, 087040 Calugareni, Romania.