New Ni (II) and Cu (II) complexes with pyridoxal-semicarbazone were synthesized and their structures were solved by X-ray crystallography. This analysis showed the bis-ligand octahedral structure of [Ni(PLSC-H)₂]·H₂O and the dimer octahedral structure of [Cu(PLSC)(SO₄)(H₂O)]₂·2H₂O. Hirshfeld surface analysis was employed to determine the most important intermolecular interactions in the crystallographic structures. The structures of both complexes were further examined using density functional theory and natural bond orbital analysis. The photocatalytic decomposition of methylene blue in the presence of both compounds was investigated. Both compounds were active toward E. coli and S. aureus, with a minimum inhibition concentration similar to that of chloramphenicol. The obtained complexes led to the formation of free radical species, as was demonstrated in an experiment with dichlorofluorescein-diacetate. It is postulated that this is the mechanistic pathway of the antibacterial and photocatalytic activities. Cyclic voltammograms of the compounds showed the peaks of the reduction of metal ions. A molecular docking study showed that the Ni(II) complex exhibited promising activity towards Janus kinase (JAK), as a potential therapy for inflammatory diseases, cancers, and immunologic disorders.

New complex Co(III) with ligand Pyridoxal-S-methyl-isothiosemicarbazone, (PLITSC) was synthesized. X-ray analysis showed the bis-ligand octahedral structure of the cobalt complex [Co(PLITSC-H)₂]BrNO₃·CH₃OH (compound 1). The intermolecular interactions governing the crystal structure were described by the Hirsfeld surface analysis. The structure of compound 1 and the corresponding Zn complex (([Zn(PLTSC)(H₂O)₂]SO₄·H₂O)) were optimized at the B3LYP/6–31 + G (d,p)/LanL2DZ level of theory, and the applicability was assessed by comparison with the crystallographic structure. The natural bond orbital analysis was used for the discussion on the stability of formed compounds. The antibacterial activity of obtained complexes towards S. aureus and E. coli was determined, along with the effect of compound 1 on the formation of free radical species. Activity of compound 1 towards the removal of methylene blue was also investigated. The voltammograms of these compounds showed the reduction of metal ions, as well as the catalyzed reduction of CO₂ in acidic media.

The use of gold nanorods (GNRs) as a contrast agent in bioimaging and cell tracking has numerous advantages, primarily due to the unique optical properties of gold nanorods which allow for the use of infrared regions when imaging. Owing to their unique geometry, Au NRs exhibit surface plasmon modes in the near-infrared wavelength range, which is ideal for carrying out optical measurements in biological fluids and tissue. Gold nanorod functionalization is essential, since the Cetyltrimethyl ammonium bromide CTAB gold nanorods are toxic, and for further in vitro and in vivo experiments the nanorods should be functionalized to become optically stable and biocompatible. In the present study, gold nanorods with an longitudinal surface plasmon resonance (LSPR) position around 800 nm were synthesized in order to be used for photoacoustic imaging applications for stem cell tracking. The gold nanorods were functionalized using both thiolated poly (ethylene glycol) (PEG) to stabilize the gold nanorods surface and a CALNN–TAT peptide sequence. Both ligands were attached to the gold nanorods through an Au–sulfur bond. CALNN–TAT is known as a cell penetrating peptide which ensures endocytosis of the gold nanorods inside the mesenchymal stem cells of mice (MSCD1). Surface modifications of gold nanorods were achieved using optical spectroscopy (UV–VIS), electron microscopy (TEM), zeta-potential, and FTIR. Gold nanorods were incubated in MSCD1 in order to achieve a cellular uptake that was characterized by a transmission electron microscope (TEM). For photoacoustic imaging, Multi-Spectral Optoacoustic Tomography (MSOT) was used. The results demonstrated good cellular uptake for PEG–CALNN–TAT GNRs and the successful use of modified gold nanorods as both a contrast agent in photoacoustic imaging and as a novel tracking bioimaging technique.

Hazardous dyes in industrial wastewater are an internationally recognized issue for community health. Nanoparticles synthesized through green protocols are a fascinating research field with numerous applications. The current study mainly aimed to investigate the degradation of Congo red (CR) dye under UV light in the presence of H₂O₂ and the photocatalytic activity of copper oxide nanoparticles (CuONPs). For CuONP formation, Citrus maxima extract contains a high number of phytochemical constituents. The size of CuONPs ranges between 25 and 90 nm. The photocatalytic activity of CuONPs with the addition of H₂O₂ was observed and analyzed under UV light to eliminate CR dye. The UV light caused the decomposition of H₂O₂, which produced ·OH radicals. The results revealed a significant increment in dye degradation during the presence of H₂O₂. The effect of concentration on the degradation of the CR dye was also studied. The degradation pathway of organic pollutants was reputable from the hydroxy radical medicated degradation of CR. Advanced Oxidation Treatment depends on the in situ production of reactive ·OH species and is presented as the most effective procedure for decontamination. The biological activity of CuONPs was evaluated against Escherichia coli Bacillus subtillis, Staphylococcus aureus, Shigella flexenari, Acinetobacter Klebsiella pneumonia, Salmonella typhi and Micrococcus luteus. The newly synthesised nanomaterials showed strong inhibition activity against Escherichia coli (45%), Bacillus subtilis (42%) and Acinetobacter species (25%). The activity of CuONPs was also investigated against different fungus species such as: Aspergillus flavus, A. niger, Candida glabrata, T. longifusus, M. Canis, C. glabrata and showed a good inhibition zone against Candida glabrata 75%, Aspergillus flavus 68%, T. longifusus 60%. The materials showed good activity against C. glaberata, A. flavus and T. longifusus. Furthermore, CuONPs were tested for antioxidant properties using 2, 2 diphenyl-1-picrylhydrazyl) (DPPH).

Biosynthesis of silver nanoparticles using natural compounds derived from plant kingdom is currently used as safe and low-cost technique for nanoparticles synthesis with important abilities to inhibit multidrug resistant microorganisms (MDR). ESKAPE pathogens, especially MDR ones, are widely spread in hospital and intensive care units. In the present study, AgNPs using Ducrosia flabellifolia aqueous extract were synthesized using a reduction method. The green synthesized D. flabellifolia-AgNPs were characterized by UV–Vis spectrophotometer, Scanning electron microscopy (SEM), and X-ray diffraction assays. The tested D. flabellifolia aqueous extract was tested for its chemical composition using Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (LC-ESI-MS). Anti-quorum sensing and anti-ESKAPE potential of D. flabellifolia-AgNPs was also performed. Results from LC-ESI-MS technique revealed the identification of chlorogenic acid, protocatechuic acid, ferulic acid, caffeic acid, 2,5-dihydroxybenzoic acid, and gallic acid as main phytoconstituents. Indeed, the characterization of newly synthetized D. flabellifolia-AgNPs revealed spherical shape with mean particle size about 16.961±2.914 nm. Bio-reduction of silver was confirmed by the maximum surface plasmon resonance of D. flabellifolia-AgNPs at 430 nm. Newly synthetized D. flabellifolia-AgNPs were found to possess important anti-ESKAPE activity with low minimal inhibitory concentrations (MICs) ranging from 0.078 to 0.312 mg/mL, and low minimal bactericidal concentrations (MBCs) varying from 0.312 to 0.625 mg/mL. Moreover, D. flabellifolia-AgNPs were active against Candida utilis ATCC 9255, C. tropicalis ATCC 1362, and C. albicans ATCC 20402 with high mean diameter of growth inhibition at 5 mg/mL, low MICs, and minimal fungicidal concentrations values (MFCs). The newly synthetized D. flabellifolia-AgNPs were able to inhibit violacein production in Chromobacterium violaceum, pyocyanin in Pseudomonas aeruginosa starter strains. Hence, the newly synthesized silver nanoparticles using D. flabellifolia aqueous extract can be used as an effective alternative to combat ESKAPE microorganisms. These silver nanoparticles can attenuate virulence of Gram-negative bacteria by interfering with the quorum sensing system and inhibiting cell-to-cell communication.

This study aims to develop innovative heterocyclic nanocomposites incorporating silver nanoparticles (SNPs) for potential therapeutic applications targeting infections, gastric ulceration, inflammation, and oxidative damage. By synthesizing new derivatives of spiro-thiazolidine-carbonitrile (Py-ST-X) and incorporating them into Ag nanoparticles (AgNPs) and carbon nanotubes (CNTs), we have prepared Ag@Py-ST-X and Ag@Py-ST-X@CNT nanocomposites, respectively. The physical properties of these materials were studied using XRD, TEM, SEM, and Zeta potential techniques. In our investigation involving rats with gastric ulcers, we observed noteworthy inhibitory effects on gastric acid enzyme activity, specifically H⁺/K⁺ATPase, by Ag@Py-ST-NO₂ and Ag@Py-ST-Br nanocomposites, demonstrating reductions of 25 and 34%, respectively, compared to untreated ulcers. Nanotubulation of these compounds further improved their inhibitory efficacy to 29 and 45%, respectively. Additionally, these nanoparticles showed the most potent myeloperoxidase (MPO)-inhibitory activity, demonstrating 36 and 49% inhibition, respectively, with nanotubulated versions reaching 44 and 53%. Moreover, Ag@Py-ST-NO₂@CNT and Ag@Py-ST-Br@CNT nanotubes showed significant antioxidant activity, reducing thiobarbituric acid reactive substances (TBARS) by 35 and 51%, and hydrogen peroxide (H₂O₂) levels by 49 and 71%, respectively. These therapeutic effects were confirmed by reductions in gastric surface area (GSA) by 44% and 52%, a decrease in ulcer index (UI) from 80% to 44 and 38%, and an increase in curative index (CI) from 19 to 55 and 62% following administration of Ag@Py-ST-NO₂@CNT and Ag@Py-ST-Br@CNT, respectively. Histological studies support these findings, suggesting the potential of these nanocomposites as promising candidates for treating various disorders.