Magnetic iron oxide nanoparticles (MIONs) cross-linked natural polymer-based hybrid gel beads: Controlled nano anti-TB drug delivery application.

The nanosized rifampicin (RIF) has been prepared to increase the solubility in aqueous solution, which leads to remarkable enhancement of its bioavailability and their convenient delivery system studied by newly produced nontoxic, biodegradable magnetic iron oxide nanoparticles (MIONs) cross-linked polyethylene glycol hybrid chitosan (mCS-PEG) gel beads. The functionalization of both nano RIF and mCS-PEG gel beads were studied using various spectroscopic and microscopic techniques. The size of prepared nano RIF was found to be 70.20 ± 3.50 nm. The mechanical stability and swelling ratio of the magnetic gel beads increased by the addition of PEG with a maximum swelling ratio of 38.67 ± 0.29 g/g. Interestingly, this magnetic gel bead has dual responsive assets in the nano drug delivery application (pH and the magnetic field). As we expected, magnetic gel beads show higher nano drug releasing efficacy at acidic medium (pH = 5.0) with maximum efficiency of 71.00 ± 0.87%. This efficacy may also be tuned by altering the external magnetic field and the weight percentage (wt%) of PEG. These results suggest that such a dual responsive magnetic gel beads can be used as a potential system in the nano drug delivery applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1039-1050, 2018.

Enhancing the anti-gastric cancer activity of curcumin with biocompatible and pH sensitive PMMA-AA/ZnO nanoparticles.

Curcumin loaded ZnO nanoparticles were successfully synthesised and encapsulated with co-polymer PMMA-AA (Cur/PMMA-AA/ZnO NPs). The ZnO nanoparticles have been converted as good cargo materials to carry the well-known hydrophobic drug curcumin by surface functionalization. Physical characteristics of these novel nanomaterials have been studied with transmission electron microscopy (TEM) and powder X-ray diffraction (XRD) in conjunction with spectral techniques. A narrow particle size distribution with an average value of 42nm was found via TEM. Most importantly, the pH-responsive release of curcumin from the nano-vehicle ensures safer, more controlled delivery of the drug at physiological pH. The drug entrapment efficiency and loading was evaluated and the in vitro efficacy as anticancer drug delivery vehicle was analyzed. The potential toxicity of Cur/PMMA-AA/ZnO NPs was studied by using AGS gastric cancer cell lines via MTT assay. These results revealed that the proposed nanomaterials induce a remarkable cell death in in-vitro models. The multifunctional properties of Cur/PMMA-AA/ZnO NPs may open up new avenues in cancer therapy through overcoming the limitations of conventional cancer therapy.

Biocompatible curcumin loaded PMMA-PEG/ZnO nanocomposite induce apoptosis and cytotoxicity in human gastric cancer cells.

Although curcumin is efficient in killing cancer cells, its poor water solubility and assocaited inadequate bioavailability remain major limitations to its therapeutic application. The formulation of curcumin micellar nanoparticles (NPs) encapsulated with a biodegradable polymer promises to significantly improve curcumin's solubility, stability, and bioavailability. The past decade has witnessed the development of nanoscale curcumin delivery systems: curcumin-loaded liposomes or nanoparticles, self-microemulsifying drug delivery systems (SMEDDS), cyclodextrin inclusions, solid dispersions, nanodisks, and nanotubes. The intention of the present investigation was to enhance the bioavailability and ultimately the efficacy of curcumin by developing a curcumin loaded PMMA-PEG/ZnO bionanocomposite utilizing insoluble curcumin and poorly soluble ZnO nanoparticles. Here, the drug (curcumin) may be carry and deliver the biomolecule(s) by polymer-encapsulated ZnO NPs. Physical characteristics of these novel nanomaterials have been studied with transmission electron microscopy (TEM) and powder X-ray diffraction (XRD) in conjunction with spectral techniques. Aqueous solubility of curcumin was augmented upon conjugation with the polymer-stabilized ZnO NPs. A narrow nanocomposite particle size distribution with an average value of 40 to 90nm was found via TEM. Most importantly, the pH-responsive release of curcumin from the nano-vehicle ensures safer, more controlled delivery of the drug at physiological pH. Cytotoxic potential and cellular uptake of curcumin loaded ZnO NPs were assessed by) cell viability assay, cell cycle assays along with the cell imaging studies have been done in addition to MTT using AGS cancer cells. Hence, these studies demonstrate that the clinical potential of the Curcumin Loaded PMMA-PEG/ZnO can induce the apoptosis of cancer cells through a cell cycle mediated apoptosis corridor, which raises its probability to cure gastric cancer cells.

Synthesis, spectral characterization and DNA bindings of tridentate N2O donor Schiff base metal(II) complexes.

To evaluate the biological preference of synthetic small drugs towards DNA target, new metal based chemotherapeutic agents of Cu(II), Co(II), Ni(II) and Zn(II), 2,4-diiodo-6-((pyridin-2-ylmethylimino)methyl)phenol (L) Schiff base complexes (1, 2, 3 &4) having N,N,O donor system respectively were synthesized and thoroughly characterized. The IR results confirmed the tridentate binding of the ligand with metal centre during complexation and reflects the proposed structure. The density function theory calculations were also used to further investigate the electronic structure and properties of ligand and complexes. The preliminary investigation of herring Sperm (HS-DNA) interaction propensity of complexes 1-4 were carried out in Tris-HCl buffer at pH 7.1 to demonstrate their mode of interactions. The obtained results reveal that these complexes significantly interact with DNA on the grooves, further, this observed mode of interactions was also confirmed by molecular docking evaluations. The complexes 1-4 were also screened for antimicrobial evaluations which demonstrated that their significant activity against various human pathogens. The cleavage studies with pBR322 plasmid DNA revealed higher nuclease activity of 1 as compared to other complexes.

A lucid build-up of nanostructured curcumin, quercetin and their interaction with DNA.

Nanostructured phyto-drugs such as curcumin and quercetin were prepared by simple sonochemical method and studied for their bio-activities. FT-IR spectra indicate that the chemical structures of these nanostructured drugs are identical with their commercially available microcrystalline counterparts. Scanning Electron Microscopic (SEM) analysis reveals that the curcumin and quercetin, form as nanocube and nanoneedle like structures respectively. These nanocrystalline drugs have enhanced solubility in neutral aqueous medium at room temperature and thus exhibit better bioavailability than their commercially available microcrystalline form. Their DNA interactions and the observed binding constants were investigated through UV-vis spectral technique. Nanocurcumin, due to its small size, exhibits significantly high DNA binding constant (1.2 x 10(6) M(-1)). The voltammetric and CD spectral changes observed for the nanocurcumin reveal its deep penetration into the core of the DNA through the minor grooves, where it forms H-bonds with the floor nitrogen/oxygen atoms of the DNA bases.

Structural characterization and remarkable axial ligand effect on the nucleophilic reactivity of a nonheme manganese(III)-peroxo complex.

The dark side of the Mn: A manganese(III) complex bearing a 13-membered macrocyclic ligand (1, see picture) binds a peroxo ligand in a side-on eta(2) fashion. The reactivity of 1 is influenced by the introduction of anionic ligands trans to the peroxo group. Electronic and structural changes upon trans-ligand binding explain the increased nucleophilicity of the resulting complexes 1-X.

Geometric and electronic structure and reactivity of a mononuclear "side-on" nickel(III)-peroxo complex.

Metal-dioxygen adducts, such as metal-superoxo and -peroxo species, are key intermediates often detected in the catalytic cycles of dioxygen activation by metalloenzymes and biomimetic compounds. The synthesis and spectroscopic characterization of an end-on nickel(II)-superoxo complex with a 14-membered macrocyclic ligand was reported previously. Here we report the isolation, spectroscopic characterization, and high-resolution crystal structure of a mononuclear side-on nickel(III)-peroxo complex with a 12-membered macrocyclic ligand, [Ni(12-TMC)(O(2))](+) (1) (12-TMC = 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane). Different from the end-on Ni(II)-superoxo complex, the Ni(III)-peroxo complex is not reactive in electrophilic reactions, but is capable of conducting nucleophilic reactions. The Ni(III)-peroxo complex transfers the bound dioxygen to manganese(II) complexes, thus affording the corresponding nickel(II) and manganese(III)-peroxo complexes. The present results demonstrate the significance of supporting ligands in tuning the geometric and electronic structures and reactivities of metal-O(2) intermediates that have been shown to have biological as well as synthetic usefulness in biomimetic reactions.

Reactivity of a cobalt(III)-peroxo complex in oxidative nucleophilic reactions.

A mononuclear cobalt(III)-peroxo complex bearing a macrocyclic tetradentate N4 ligand, [CoIII(TMC)(O2)]+ (TMC=1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane), was generated in the reaction of [CoII(TMC)]2+ and H2O2 in the presence of triethylamine in CH3CN. The reactivity of the cobalt(III)-peroxo complex was investigated in aldehyde deformylation with various aldehydes and compared with that of iron(III)- and manganese(III)-peroxo complexes, such as [FeIII(TMC)(O2)]+ and [MnIII(TMC)(O2)]+. In this reactivity comparison, the reactivities of metal-peroxo species were found to be in the order of [MnIII(TMC)(O2)]+ > [CoIII(TMC)(O2)]+ > [FeIII(TMC)(O2)]+. A positive Hammett rho value of 1.8, obtained in the reactions of [CoIII(TMC)(O2)]+ and para-substituted benzaldehydes, demonstrates that the aldehyde deformylation by the cobalt(III)-peroxo species occurs via a nucleophilic reaction.

Identification of an "end-on" nickel-superoxo adduct, [Ni(tmc)(O2)]+.

An "end-on" Ni2+-superoxo adduct has been prepared via two independent synthetic routes and its structure ascertained by spectroscopic and computational methods. The new structure type in nickel coordination chemistry is supported by resonance Raman and EPR spectroscopic features, the former displaying a high frequency nu (O-O) mode (1131 cm-1) consistent with significant superoxo character. The Ni2+-superoxo adduct oxidizes PPh3 to OPPh3 in quantitative yield.

Mononuclear nonheme ferric-peroxo complex in aldehyde deformylation.

A mononuclear nonheme ferric-peroxo complex bearing a macrocyclic tetradentate N4 ligand, [(TMC)Fe(III)-O2]+, was prepared and used in mechanistic studies of aldehyde deformylation; a catalytic aldehyde deformylation by a nonheme iron(II) complex, [Fe(II)(TMC)]2+, and molecular oxygen is reported as well.