Design and development of bioactive α-hydroxy carboxylate group modified MnFe2O4 nanoparticle: Comparative fluorescence study, magnetism and DNA nuclease activity. (September 2017) - Chakraborty, Indranil
Abstract: Three new α-hydroxy carboxylate group functionalized MnFe2 O4 nanoparticles (NPs) have been developed to explore the microscopic origin of ligand modified fluorescence and magnetic properties of nearly monodispersed MnFe2 O4 NPs. The surface functionalization has been carried out with three small organic ligands (tartrate, malate, and citrate) having different number of α-hydroxy carboxylate functional group along with steric effect. Detailed study unveils that α-hydroxy carboxylate moiety of the ligands plays key role to generate intrinsic fluorescence in functionalized MnFe2 O4 NPs through the activation of ligand to metal charge transfer transitions, associated with ligand–Mn 2+ /Fe 3+ interactions along with d – d transition corresponding to d –orbital energy level splitting of Fe 3+ ions on NP surface. Further, MnFe2 O4 NPs show a maximum 140.88% increase in coercivity and 97.95% decrease in magnetization compared to its bare one upon functionalization. The ligands that induce smallest crystal field splitting of d –orbital energy level of transition metal ions are found to result in strongest ferrimagnetic activation of the NPs. Finally, our developed tartrate functionalized MnFe2 O4 (T-MnFe2 O4 ) NPs have been utilized for studying DNA binding interaction and nuclease activity for stimulating their beneficial activities toward diverse biomedical applications. The spectroscopic measurements indicate that T-MnFe2 O4 NPs bind calf thymus DNA by intercalative mode. The ability of T-MnFe2 O4 NPs to induce DNA cleavage was studied by gel electrophoresis technique where the complex is found to promote the cleavage of pBR322 plasmid DNA from the super coiled form I to linear coiled form II and nicked coiled form III with good efficiency. Graphical abstract: Highlights: Synthesis of MnFe2 O4 nanoparticles and their functionalization with tartrate, malate and citrate ligands. Tartrate induces better fluorescence property in MnFe2O4 nanoparticles than malate and citrate ones. Tartrate modified MnFe2 O4 nanoparticles bind and stabilise the DNA helix due to intercalation.