A Step into Medicine for New Silver(I) Complexes-From Antimicrobial Properties to Regenerative Potential

Silver complexes are potential antimicrobial agents that trigger destructive processes in bacterial cells, leading to their death. Their ability to simultaneously stimulate tissue regenerative properties also makes them promising components in the development of medical materials. A common complication arising from the treatment of bone tissue damage is hospital-acquired infection, requiring repeated revision surgeries. The use of bone grafts with antibacterial properties can help solve this problem. New pyridine complexes of silver(I) with thiophenecarboxylic (Htph) and nitric acid anions have been synthesized: [Ag(tph)(py)₂]_n·nHtph (1, py-pyridine) and [Ag(bpy)]_n·nNO₃ (2, bpy-4,4'-bipyridine), the structures of which have been determined using X-ray analysis. Despite the fact that 2 is a known structure, we were able to obtain new cell parameters by conducting an X-ray diffraction analysis at a lower temperature of 100 K. According to X-ray diffraction data, both compounds are polymers in which the cationic part is formed by linear fragments (CN_Ag = 2) [Ag(py)₂]⁺ (1)/[Ag(bpy)₂]⁺ (2), and acid anions act as counterions. The presence of intermolecular and non-valent π-π interactions provides additional stabilization of supramolecular levels. Aqueous solutions 1 and 2 are stable for two weeks, according to UV-Vis data. Incubation of crosslinked resorbable polymer matrices functionalized separately with complex 1 or 2 in saline solution revealed a sustained, prolonged release of silver ions over 14 days. Evaluation of the antimicrobial potential of 1 and 2 against Gram-positive/Gram-negative species and fungi demonstrated moderate, controlled bacteriostatic growth inhibition broadly across tested strains, confirming the bifunctionality of the crosslinked hybrid matrix systems-moderate suppression of bacterial growth while simultaneously stimulating tissue regeneration. An increase in cell viability, expressed in their active proliferation under the influence of complexes 1 and 2 up to 156%, as well as calcium deposition, indicates the high cytocompatibility and pro-mineralization capacity of the new compounds.