Synthesis, structural characterization, antibacterial activity and computational studies of new cobalt (II) complexes with 1,1,3,3-tetrakis (3,5-dimethyl-1-pyrazolyl)propane ligand

Cobalt-mediated multi-functional dressings promote bacteria-infected wound healing

Wound dressings with multiple functions are required to meet the complexity of the wound healing process. The multifunctionality often leads to an increase in the complexity and difficulty in dressing preparation. To surmount this problem, we used a facile preparation and fabrication process to fabricate a multi-functional dressing by integrating four widely accessible materials: plain gauze, sodium alginate (SA), Ca²⁺ and Co²⁺. Firstly, mixed Ca²⁺/Co²⁺ ion solutions with different concentration were applied to gauzes. After drying, SA solution was added to ionized gauze and Co²⁺-Ca²⁺/Gauze/SA (Ion-GSA) composite dressings were formed easily. In vitro results showed that all Ion-GSA dressings exhibited strong mechanical properties, uniform dispersion and sustained release of Ca²⁺ and Co²⁺, and the ability to retain moisture and absorb wound exudate. Besides the above advantages, dressings prepared with 0.25 g/L Co²⁺ and 4 g/L Ca²⁺ (Co²⁺0.25-Ca²⁺4 GSA composite dressings) exhibited the best overall effect for inducing a hypoxia-like response, and favorable cytocompatibility, hemostatic property and antibacterial activity. In vivo wound healing assays revealed that Co²⁺0.25-Ca²⁺4 GSA composite dressings inhibited bacterial growth, increased local Hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), transforming growth factor-β1 (TGF-β1) protein expression, and accelerated full-thickness skin wound healing in mouse bacterial-infected wound model. The quick healing wounds had improved angiogenesis, macrophages regulation, re-epithelialization and dense collagen deposition. Collectively, our results indicated that Co²⁺0.25-Ca²⁺4 GSA composite dressings promote wound healing. STATEMENT OF SIGNIFICANCE: Wound dressings with integrated functionalities are required to meet complex clinical requirements. However, there is often a trade-off between reducing preparation complexity and increasing the multifunctionality of the dressing's properties. In this study, we prepared multifunctional composite dressings by a facile preparation process using widely accessible materials. The composite dressings possessed the mechanical strength of gauze, had the effective wound exudate absorption, moisture maintenance and hemostatic property capacity of calcium alginate hydrogels, and had the hypoxia-like induction and the antimicrobial effects of Co²⁺. These functions all together promote bacteria-infected wound healing. Thus, we believed that the composite dressings can be widely applied in skin wound repair duo to their facile preparation method and good therapeutic effect.

Synthesis, structural characterization, QSAR and docking studies of a new binuclear nickel (II) complex based on the flexible tetradentate N-donor ligand as a potent antibacterial and anticancer agent

A new nickel (II)complex namely [Ni₂(Lt)Cl₄] derived from the NiCl₂.6H₂O and 1,1,3,3-tetrakis(3,5-dimethyl-1-pyrazolyl)propane (Lt) has been synthesized and fully characterized by the single crystal X-ray diffraction, elemental analysis, FT-IR, UV-vis, density functional theory (DFT) calculations, antibacterial and anticancer activities. In the title complex, each of the Ni(II) atoms is tetrahedrally coordinated by two N atoms from one of the chelating bidentate bis(3,5-dimethylpyrazolyl)methane units of the Lt ligand and two Cl as terminal ligands. The neighboring [Ni₂(Lt)Cl₄] molecules are linked together by the intermolecular CH⋯Cl hydrogen bonds to generate a 1D chain structure. The chains are further stabilized by the intermolecular CH⋯π interactions to form a two-dimensional non-covalent bonded structure. The antibacterial activity of the free Lt ligand and its Ni (II) complex shows that the ability of these compounds to inhibit growth of the tested bacteria increase from the Lt to binuclear nickel (II) complex. Scanning probe microscopy (SPM) study of the treated B. subtilis and E. coli bacteria was implemented to understand the structural changes caused by the interactions between the nickel (II) complex and the target bacteria. The cytotoxicity test of the Lt ligand and its complex was evaluated against the human carcinoma cell line (Caco-2) using the MTT assay. The results indicate that the Lt ligand and its complex display cytotoxicity against Caco-2 with the IC50 values of 36.29μM and 12.97μM, respectively. Therefore, the complex can be nominated as a potential anticancer agent. Molecular docking investigations on the five standard antibiotic, five standard anticancer drugs, free Lt ligand, title complex and twelve receptors were performed by Autodock vina function. The results of docking and DFT calculations are in line with the in vitro data obtained via the antibacterial and anticancer activity of Lt ligand and its made-complex.