A new complex of holmium, [Ho(bpy)(H₂O)₆]Cl₃has been synthesized, their DNA/BSA/HSA binding, molecular docking, antibacterial activity and MTT assay of niosome nano-encapsulated are investigated.

Based on the potential anticancer properties of lanthanide complexes, the anticancer activity of the Sm(III) complex containing a 2,2′-bipyridine ligand (bpy) and its interaction with FS-DNA (Fish-Salmon DNA) and BSA (Bovine Serum Albumin) were examined experimentally and by molecular docking in this paper. Absorption and fluorescence spectroscopic methods were used to define the thermodynamic parameters, binding constant (K_b), and the probable binding mechanism. It was concluded that the Sm complex interacts with FS-DNA through a minor groove with a K_b of 10⁵ M⁻¹. Also, the K_b for the BSA binding at 298 K was found to be 5.89 × 10⁵ M⁻¹, showing relatively a high tendency of the Sm complex to DNA and BSA. Besides, the Sm complex was docked to BSA and DNA by the autodock program. The results of the docking calculations were in good agreement with the experimental examinations. Additionally, the antifungal and antibacterial properties of this complex were investigated. The anticancer tests on the effect of the Sm complex, starch nano-encapsulation, and lipid nano-encapsulation in MCF-7 and A-549 cell lines were performed by the MTT method. It can be observed that the Sm complex and its nanocarriers presented a selective inhibitory effect on various cancer cell growths.

Agarose gel electrophoresis, absorption, fluorescence, viscosity, and circular dichroism (CD) have been used in exploring the interaction of terbium(III) complex, [Tb(bpy)₂Cl₃(OH₂)] where bipy is 2,2′-bipyridine, with Fish salmon DNA. Agarose gel electrophoresis assay, along with absorption and fluorescence studies, reveal interaction between the corresponding complex and FS-DNA. Also, the binding constants (K_b) and the Stern–Volmer quenching constants (K_sv) of Tb(III) complex with FS-DNA were determined. The calculated thermodynamic parameters suggested that the binding of mentioned complex to FS-DNA was driven mainly by hydrophobic interactions. A comparative study of this complex with respect to the effect of iodide-induced quenching, ionic strength effect, and ethidium bromide exclusion assay reflects binding of explicit to the FS-DNA primarily in a groove fashion. CD and viscosity data also support the groove binding mode. Furthermore, Tb(III) complex have been simultaneously screened for their antibacterial and antifungal activities.

In this study, the interactions of a novel metal complex [Dy(bpy)₂Cl₃.OH₂] (bpy is 2,2'-bipyridine) with fish salmon DNA (FS-DNA) and bovine serum albumin (BSA) were investigated by experimental and theoretical methods. All results suggested significant binding between the Dy(III) complex with FS-DNA and BSA. The binding constants (K_b), Stern-Volmer quenching constants (K_SV) of Dy(III)-complex with FS-DNA and BSA at various temperatures as well as thermodynamic parameters using Van’t Hoff equation were obtained. The experimental results from absorption, ionic strength, iodide ion quenching, ethidium bromide (EtBr) quenching studies and positive ΔH˚ and ΔS˚ suggested that hydrophobic groove-binding mode played a predominant role in the binding of Dy(III)-complex with FS-DNA. Indeed, the molecular docking results for DNA-binding were in agreement with experimental data. Besides, the results found from experimental and molecular modeling indicated that the Dy(III)-complex bound to BSA via Van der Waals interactions. Moreover, the results of competitive tests by phenylbutazone, ibuprofen, and hemin (as a site-I, site-II and site-III markers, respectively) considered that the site-III of BSA is the most possible binding site for Dy(III)-complex. In addition, Dy(III) complex was concurrently screened for its antimicrobial activities. The presented data provide a promising platform for the development of novel metal complexes that target nucleic acids and proteins with antimicrobial activity.

In this work, the terbium(III), dysprosium(III), and ytterbium(III) complexes containing 2, 2′-bipyridine (bpy) ligand have been synthesized and characterized using CHN elemental analysis, FT-IR, UV–Vis and ¹H-NMR techniques and their binding behavior with human serum albumin (HSA) was studied by UV–Vis, fluorescence and molecular docking examinations. The experimental data indicated that all three lanthanide complexes have high binding affinity to HSA with effective quenching of HSA fluorescence via static mechanism. The binding parameters, the type of interaction, the value of resonance energy transfer, and the binding distance between complexes and HSA were estimated from the analysis of fluorescence measurements and Förster theory. The thermodynamic parameters suggested that van der Waals interactions and hydrogen bonds play an important role in the binding mechanism. While, the energy transfer from HSA molecules to all these complexes occurs with high probability, the order of binding constants (BpyTb > BpyDy > BpyYb) represents the importance of radius of Ln³⁺ ion in the complex-HSA interaction. The results of molecular docking calculation and competitive experiments assessed site 3 of HSA, located in subdomain IB, as the most probable binding site for these ligands and also indicated the microenvironment residues around the bound mentioned complexes. The computational results kept in good agreement with experimental data.