Selective and sensitive CQD-based sensing platform for Cu2+ detection in Wilson's disease

Excessive Cu2+ intake can cause neurological disorders (e.g. Wilson's disease) and adversely affect the gastrointestinal, liver, and kidney organs. The presence of Cu2+ is strongly linked to the emergence and progression of Wilson's disease (WD), and accurately measuring the amount of copper is a crucial step in diagnosing WD at an early stage in a clinical setting. In this work, CQDs were fabricated through a facile technique as a novel fluorescence-based sensing platform for detecting Cu(II) in aqueous solutions, and in the serum samples of healthy and affected individuals by WD. The CQDs interact with Cu(II) ions to produce Turn-on and Turn-off states at nano-molar and micro-molar levels, respectively, with LODs of 0.001 µM and 1 µM. In fact, the Cu2+ ions can act like a bridge between two CQDs by which the charge and electron transfer between the CQDs may increase, possibly can have significant effects on the spectroscopic features of the CQDs. To the best of our knowledge, this is the first reported research that can detect Cu(II) at low levels using two different complexation states, with promising results in testing serum. The potential of the sensor to detect Cu(II) was tested on serum samples from healthy and affected individuals by WD, and compared to results obtained by ICP-OES. Astonishingly, the results showed an excellent correlation between the measured Cu(II) levels using the proposed technique and ICP-OES, indicating the high potential of the fluorimetric CQD-based probe for Cu(II) detection. The accuracy, sensitivity, selectivity, high precision, accuracy, and applicability of the probe toward Cu(II) ions make it a potential diagnostic tool for Wilson's disease in a clinical setting.

Bipyridine Ruthenium(II) Complexes with Halogen-Substituted Salicylates: Synthesis, Crystal Structure, and Biological Activity

Ruthenium complexes currently represent a perspective subject of investigation in terms of potential anticancer therapeutics. Eight novel octahedral ruthenium(II) complexes are the subject of this article. Complexes contain 2,2'-bipyridine molecules and salicylates as ligands, differing in position and type of halogen substituent. The structure of the complexes was determined via X-ray structural analysis and NMR spectroscopy. All complexes were characterized by spectral methods-FTIR, UV-Vis, ESI-MS. Complexes show sufficient stability in solutions. Therefore, their biological properties were studied. Binding ability to BSA, interaction with DNA, as well as in vitro antiproliferative effects against MCF-7 and U-118MG cell lines were investigated. Several complexes showed anticancer effects against these cell lines.

Structural and Biological Properties of Heteroligand Copper Complexes with Diethylnicotinamide and Various Fenamates: Preparation, Structure, Spectral Properties and Hirshfeld Surface Analysis

Herein, we discuss the synthesis, structural and spectroscopic characterization, and biological activity of five heteroligand copper(II) complexes with diethylnicotinamide and various fenamates, as follows: flufenamate (fluf), niflumate (nifl), tolfenamate (tolf), clonixinate (clon), mefenamate (mef) and N, N-diethylnicotinamide (dena). The complexes of composition: [Cu(fluf)2(dena)2(H2O)2] (1), [Cu(nifl)2(dena)2] (2), [Cu(tolf)2(dena)2(H2O)2] (3), [Cu(clon)2(dena)2] (4) and [Cu(mef)2(dena)2(H2O)2] (5), were synthesized, structurally (single-crystal X-ray diffraction) and spectroscopically characterized (IR, EA, UV-Vis and EPR). The studied complexes are monomeric, forming a distorted tetragonal bipyramidal stereochemistry around the central copper ion. The crystal structures of all five complexes were determined and refined with an aspheric model using the Hirshfeld atom refinement method. Hirshfeld surface analysis and fingerprint plots were used to investigate the intermolecular interactions in the crystalline state. The redox properties of the complexes were studied and evaluated via cyclic voltammetry. The complexes exhibited good superoxide scavenging activity as determined by an NBT assay along with a copper-based redox-cycling mechanism, resulting in the formation of ROS, which, in turn, predisposed the studied complexes for their anticancer activity. The ability of complexes 1–4 to interact with calf thymus DNA was investigated using absorption titrations, viscosity measurements and an ethidium-bromide-displacement-fluorescence-based method, suggesting mainly the intercalative binding of the complexes to DNA. The affinity of complexes 1–4 for bovine serum albumin was determined via fluorescence emission spectroscopy and was quantitatively characterized with the corresponding binding constants. The cytotoxic properties of complexes 1–4 were studied using the cancer cell lines A549, MCF-7 and U-118MG, as well as healthy MRC-5 cells. Complex 4 exhibited moderate anticancer activity on the MCF-7 cancer cells with IC50 = 57 μM.

Copper(II) complexes with non-steroidal anti-inflammatory drugs: Structural characterization, in vitro and in silico biological profile

Six novel copper(II) complexes with the non-steroidal anti-inflammatory drugs ibuprofen, loxoprofen, fenoprofen and clonixin as ligands were synthesized and characterized by diverse techniques including single-crystal X-ray crystallography. The in vitro scavenging activity of the complexes against 1,1-diphenyl-picrylhydrazyl and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) free radicals and the ability to reduce H₂O₂ were studied in the context of the antioxidant activity studies. The complexes may interact with calf-thymus DNA via intercalation as revealed by the techniques employed. The affinity of the complexes for bovine and human serum albumins was evaluated by fluorescence emission spectroscopy and the corresponding binding constants were determined. Molecular docking simulations on the crystal structure of calf-thymus DNA, human and bovine serum albumins were also employed in order to study in silico the ability of the studied compounds to bind to these target biomacromolecules, in terms of impairment of DNA and transportation through serum albumins, to explain the observed in vitro activity and to establish a possible mechanism of action.

Tailoring copper(ii) complexes with pyridine-4,5-dicarboxylate esters for anti-Candida activity

Five novel copper(ii) complexes with pyridine-4,5-dicarboxylate esters as ligands, [Cu(NO₃)(py-2tz)(H₂O)₃]NO₃ (1), [Cu(NO₃)₂(py-2metz)(H₂O)] (2), [Cu(NO₃)₂(py-2py)(H₂O)]·H₂O (3), [CuCl₂(py-2tz)]₂ (4) and [CuCl₂(py-2metz)]_n (5) (py-2tz is dimethyl 2-(thiazol-2-yl)pyridine-4,5-dicarboxylate, py-2metz is dimethyl 2-(4-methylthiazol-2-yl)pyridine-4,5-dicarboxylate and py-2py is dimethyl 2,2'-bipyridine-4,5-dicarboxylate), were synthesized and structurally characterized by different spectroscopic and electrochemical methods. The structure of these complexes was determined by single-crystal X-ray diffraction analysis, confirming the bidentate coordination mode of the corresponding pyridine-4,5-dicarboxylate ester to the Cu(ii) ion through the nitrogen atoms. The antimicrobial potential of copper(ii) complexes 1-5 was assessed against two bacterial and two Candida species. These complexes showed better growth inhibiting activity against Candida spp. with respect to the tested bacterial species, also being moderately toxic towards normal human lung fibroblast cells (MRC-5). Complexes 1 and 4 showed the greatest ability to inhibit the filamentation of C. albicans, which is an important process during fungal infection, and these two complexes efficiently inhibited the biofilm formation of C. albicans at subinhibitory concentrations. Complex 4 also successfully prevented the adhesion of C. albicans in an in vitro epithelial cell model. The mechanism of the antifungal activity of copper(ii) complexes 1-5 was studied through their interaction with ct-DNA, as one of the possible target biomolecules, by fluorescence spectroscopy and gel electrophoresis. Finally, the ability of these complexes to bind to bovine serum albumin (BSA) was studied by fluorescence emission spectroscopy.

Copper(II) complexes with meclofenamate ligands: Structure, interaction with DNA and albumins, antioxidant and anticholinergic activity

The interaction of copper(II) with the non-steroidal anti-inflammatory drug sodium meclofenamate (Na-mclf) in the presence or absence of the nitrogen-donor co-ligands pyridine (py) or 2,2'-bipyridylamine (bipyam), yielded the novel Cu(II) complexes [Cu₂(mclf-O,O')₄(MeOH)₂]·2MeOH (1·2MeOH), [Cu(mclf-O)₂(py)₃]·H₂O·0.5MeOH (2·H₂O·0.5MeOH) and [Cu(mclf-O,O')₂(bipyam)] (3). The characterization of the complexes was achieved by various techniques, including single-crystal X-ray crystallography. In order to study the binding mode and strength of the complexes to calf-thymus (CT) DNA, various techniques were employed which suggested intercalation between the DNA-bases as the most possible interaction mode. Competitive studies with ethidium bromide (EB) revealed the ability of the complexes to displace the EB from the EB-DNA adduct, verifying the intercalative binding mode. The affinity of the complexes to bovine and human serum albumin proteins (SAs) was investigated by fluorescence emission spectroscopy and the corresponding binding constants bear relatively high values, showing that the complexes bind tightly and possibly reversibly to SAs. The antioxidant activity of the complexes against 1,1-diphenyl-picrylhydrazyl (DPPH), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals and the ability to reduce H₂O₂ proved to be of significant magnitude. The in vitro inhibitory activity against the enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) was evaluated, in order to assess the anticholinergic ability of the complexes, which appeared promising.