New series of metal complexes by amphiphilic biopolymeric Schiff bases from modified chitosans: Preparation, characterization and effect of molecular weight on its biological applications

To improve biological activity of chitosans, new Zn(II), Pd(II) and Pt(II) complexes with biopolymeric amphiphilic Schiff bases anchored in different molecular weight chitosans matrices modified with salicylaldehyde and glycidol were prepared. Salicylaldehyde was introduced to generate complexing Schiff base sites in the chitosans matrix while glycidol is intended to increase the water solubility of the resulting biopolymeric complexes. These novel complexes were characterized using various techniques and assayed for antimicrobial and antitumor activity. The effectiveness of modification was evaluated using FTIR spectroscopy, and thermal behavior of the complexes by TG/DTG-DTA. XPRD showed that the crystallinity of the ligand diminished after the metal complexation. Surface morphologies, investigated by SEM, revealed that the complexes are rougher than chitosan matrix, and the presence of metallic ions was confirmed by EDX. Electronic spectra suggested square planar geometry for Pd(II) and Pt(II) complexes. Concerning antimicrobial activity, the novel complexes exhibited higher antibacterial efficiency against Pseudomonas syringae than against the Fusarium graminearum fungi regarding the free ligand. Complexes also exhibited high antitumor effects against the MCF-7 breast cancer cells, with certain selectivity regarding non-tumor cells (Balb/C 3T3 clone A31) depending on concentration and molar mass, indicating that they could potentially be used for antitumor applications.