Two multifunctional zero-dimensional Gd(III) complexes: magnetocaloric effect and anticancer mechanisms for lung cancer.

Two Gd(III) complexes [GdL(HO)(NO)(CHOH)(CHCHOH)] (Gd1) and [Gd(OOCCH)L(HO)]•2(HO) (Gd2) (HL = 2-pyridylcarboxaldehyde isonicotinoylhydrazone) were synthesized with a Schiff base ligand. Crystallographic study reveals both Gd1 and Gd2 have a zero-dimensional mononuclear or binuclear structure. Magnetic investigations demonstrate that Gd1 and Gd2 exhibit potential magnetocaloric effects due to Gd(III) ions, which provide negligible magnetic anisotropy, and possess low-lying excited spin states. The antiproliferative activity of Gd1 and Gd2 to three tumor cell lines was conducted and the results showed Gd1 and Gd2 showed more pronounced antiproliferative activity to A549 cells better than cisplatin. The administration of Gd1 and Gd2 led to an increase in apoptosis among A549 cells in a concentration-dependent manner, along with a corresponding rise in the levels of reactive oxygen species (ROS) within the cells. Besides, Gd1 and Gd2 were able to significantly inhibit tumor cell migration. Cell cycle assay in A549 cells revealed that cell cycle was arrested of G0/G1 phase. Western blotting analysis showed that Gd1 and Gd2 complexes could promote apoptosis in A549 cells by modulating the expression of Bcl-2 and Bax proteins.