Nanoscale ruthenium(iii) complexes with bioactive ligands: structural, colloidal, and dual antimicrobial–cytotoxic investigations

Abstract

This study comprehensively analyses two new ruthenium(III) complexes, [RuIIICl4(Nic)2][(CH3)2NH2]+DMF, 1, and [RuIIICl2(3-HPA)2][3-HH2PA]+(EtOH)2, 2, (where Nic = nicotinic acid (vitamin B3), 3-HPA = anion of a 3-hydroxypicolinic acid), as potential antimicrobial agents, highlighting their physicochemical properties, nanoparticle formation, and cytotoxic activity. The complexes were fully characterised by a single crystal X-ray diffraction technique, Fourier-transform infrared, energy-dispersive X-ray, and electron paramagnetic resonance spectroscopies. The synthesis of micro- and nanoparticles (NPs) of these complexes was performed using the liquid anti-solvent crystallisation method. The formation of NPs was confirmed, and their sizes were determined using scanning electron microscopy and dynamic light scattering techniques. The Debye-Scherrer technique, based on powder diffraction X-ray data, indicated the high crystallinity of the nanomaterials. Toxicity and morphological effects on L929 fibroblasts, hepatocellular carcinoma (Hep-G2) and human epithelial colorectal adenocarcinoma (Caco-2) cell lines of the complexes were assessed using the MTT assay and an inverted phase-contrast microscope, respectively. Complex 1 is a promising anti-cancer drug candidate targeting intestinal cancers, showing cytotoxicity against Caco-2 cancer cells and no cytotoxicity against L929 fibroblast cells, while complex 2 is markedly cytotoxic. The antibacterial activity of the complexes was assessed against methicillin-resistant Staphylococcus aureus (MRSA) and Klebsiella pneumoniae strains using the minimum inhibitory concentration (MIC) method. Complex 2 demonstrates superior bactericidal properties, achieving MIC values as low as 125 μg ml−1 for S. aureus, while complex 1 exhibits lower antimicrobial efficacy. The role of ligand composition in modulating bioactivity was examined.

Graphical abstract: Nanoscale ruthenium(iii) complexes with bioactive ligands: structural, colloidal, and dual antimicrobial–cytotoxic investigations

Supplementary files

Article information

Article type
Paper
Submitted
03 Aug 2025
Accepted
15 Aug 2025
First published
25 Aug 2025
This article is Open Access
Creative Commons BY license

Dalton Trans., 2025, Advance Article

Nanoscale ruthenium(III) complexes with bioactive ligands: structural, colloidal, and dual antimicrobial–cytotoxic investigations

O. Impert, N. Czerniecka, N. Balińska, B. Kubiak, A. Kozakiewicz-Piekarz, O. Pryshchepa, P. Pomastowski, M. Ehlert, M. Witwicki, Y. R. Pateda, E. Rakovský, A. Katafias and R. van Eldik, Dalton Trans., 2025, Advance Article , DOI: 10.1039/D5DT01857A

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