Sub 1 nm Poly(acrylic acid)-Capped Copper Nanoparticles for the Synthesis of 1,2,3-Triazole Compounds.

The stable, water-soluble, and fluorescent sub 1 nm sized poly(acrylic acid)-capped copper nanoparticles (PAACC NPs) were synthesized using a high-intensity ultrasound sonication (30 KHz) method. The reduction of copper NPs from copper(II) salt by mild reducing agent l-ascorbic acid in an aqueous medium was achieved in the presence of poly(acrylic acid). The PAACC NPs were characterized by DRS UV-visible, XPS, PL, FESEM, and HRTEM techniques. The resulting PAACC NPs show orange fluorescence with a peaking center at 560 nm. The PAACC NPs serve as effective catalysts for the synthesis of 1,2,3-triazoles via click reaction in good yields under mild reaction conditions.

Crystal structures and Hirshfeld surface analyses of 4,4'-{[1,3-phenyl-enebis(methyl-ene)]bis-(-oxy)}bis-(3-meth-oxy-benzaldehyde) and 4,4'-{[(1,4-phenyl-ene-bis(methyl-ene)]bis-(-oxy)}bis-(3-meth-oxy-benzalde-hyde).

The title compounds, C24H22O6 (I) and C24H22O6 (II), each crystallize with half a mol-ecule in the asymmetric unit. The whole mol-ecule of compound (I) is generated by twofold rotation symmetry, the twofold axis bis-ecting the central benzene ring. The whole mol-ecule of compound (II) is generated by inversion symmetry, the central benzene ring being located on an inversion center. In (I), the outer benzene rings are inclined to each other by 59.96 (10)° and by 36.74 (9)° to the central benzene ring. The corresponding dihedral angles in (II) are 0.0 and 89.87 (12)°. In the crystal of (I), mol-ecules are linked by C-H⋯O hydrogen bonds and C-H⋯π inter-actions, forming ribbons propagating along the [10] direction. In the crystal of (II), mol-ecules are linked by C-H⋯O hydrogen bonds, forming a supra-molecular framework. The Hirshfeld surface analyses indicate that for both compounds the H⋯H contacts are the most significant, followed by O⋯H/H⋯O and C⋯H/H⋯C contacts.

The crystal structures and Hirshfeld surface analysis of N',N'''-((1E,1'E)-{[methyl-enebis(-oxy)]bis-(6-bromo-3,1-phenyl-ene)}bis-(methan-ylyl-idene))bis-(isonicotinohydrazide) dihydrate and N',N'''-((1E,1'E)-{[butane-1,4-diylbis(-oxy)]bis-(2,1-phenyl-ene)}bis-(methan-ylyl-idene))bis-(isonicotino-hydrazide) [+ solvent].

The title compounds, C27H20Br2N6O4·2H2O, (I), and C30H28N6O4·[+ solvent], (II), both crystallize with one half-mol-ecule in the asymmetric unit. The whole mol-ecule of (I) is generated by twofold rotation symmetry, with the twofold rotation axis bis-ecting the C atom of the -O-CH2-O- bridge. This results in a folded or U-shaped conformation of the mol-ecule. The whole mol-ecule of (II) is generated by inversion symmetry, with the central CH2-CH2 bond of the -O-(CH2)4-O- bridge being located about a center of inversion. This results in a step-like conformation of the mol-ecule. The central C(=O)N-N=C regions of the isonicotinohydrazide moieties in both compounds are planar and the configuration about the imine C=N bonds is E. In compound (I), the benzene and pyridine rings are inclined to each other by 37.60 (6)°. The two symmetry-related pyridine rings are inclined to each other by 74.24 (6)°, and the two symmetry-related benzene rings by 7.69 (6)°. In compound (II), the benzene and pyridine rings are inclined to each other by 25.56 (11)°. The symmetry-related pyridine rings are parallel, as are the two symmetry-related benzene rings. In the crystal of (I), a pair of water mol-ecules link the organic mol-ecules via Owater-H⋯O and Owater-H⋯N hydrogen bonds, forming chains along [001], and enclosing an R 4 2(8) and two R 1 2(5) ring motifs. The chains are linked by N-H⋯Npyridine hydrogen bonds, forming a supra-molecular framework. There are also a number of C-H⋯O hydrogen bonds, and C-H⋯π and offset π-π inter-actions [inter-planar distance = 3.294 (1) Å] present reinforcing the framework. In the crystal of (II), mol-ecules are linked by N-H⋯Npyridine hydrogen bonds, forming a supra-molecular framework. Here too there are also a number of C-H⋯O hydrogen bonds present, and a C-H⋯π inter-action, reinforcing the framework. For compound (II), a region of disordered electron density was corrected for using the SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18] routine in PLATON. Their formula mass and unit-cell characteristics were not taken into account during refinement.

Green synthesis of multifunctional PEG-carboxylate π back-bonded gold nanoconjugates for breast cancer treatment.

BACKGROUND: Surface functionalization of gold nanoparticles (AuNPs) has emerged as a promising field of research with enormous biomedical applications. The folate (FA)-attached polymer-gold nanoconjugates play vital role in targeting the cancer cells. METHODS: AuNPs were synthesized by using di- or tri-carboxylate-polyethylene glycol (PEG) polymers, including citrate-PEG (CPEG), malate-PEG (MAP), and tartrate-PEG (TAP), as a reducing and stabilizing agent. After synthesis of polymer-AuNPs, the freely available hydroxyl and carboxylate groups of CPEG, MAP, and TAP were used to attach a cancer cell-targeting agent, FA, via a 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxy succinimide coupling reaction to obtain FA-CPEG-AuNP, FA-MAP-AuNP, and FA-TAP-AuNP nanocon-jugates, respectively. The 5-fluorouracil (5FU) was attached to π back-bonded carbonyl oxygens of the nanoconjugates, and the in vitro drug release profile was studied by high pressure liquid chromatography. Biocompatibility profiles of the FA-CPEG-AuNP, FA-MAP-AuNP, and FA-TAP-AuNP nanoconjugates were investigated using adult human dermal fibroblasts. Anti-breast cancer activity of 5FU-loaded nanoconjugates was investigated using MCF-7 breast cancer cells. RESULTS: X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy analyses confirmed that AuNPs attached to CPEG, MAP, or TAP via the formation of π back bonding between AuNPs and the ester carbonyl group. The π back-bonded nanoconjugates exhibited sustained release of 5FU up to 27 days. FA-MAP-AuNPs exhibited an IC50 at 5 µg/mL, while FA-CPEG-AuNPs and FA-TAP-AuNPs showed the IC50 at 100 µg/mL toward MCF-7 cancer cells. CONCLUSION: The developed polymer π back-bonded multifunctional gold nanoconjugates could be used as a potential drug delivery system for targeting MCF-7 cancer cells.

κ-Carrageenan: An effective drug carrier to deliver curcumin in cancer cells and to induce apoptosis.

The current study is to develop a natural drug carrier with seaweed derived polymers namely κ-Carrageenan (κ-Car) for drug delivery applications. κ-Car is a natural polysaccharide which derived from edible red seaweeds, they are easily available, non-toxic, cost effective, biodegradable and biocompatible nature. Curcumin (Cur) is a yellow-orange polyphenol existing in turmeric, which is predominantly used as spice and food coloring agent. The ultimate use of polymeric composites, especially those composed of natural polymers, has become a very interesting approach in recent drug delivery applications, due to their non-toxicity and biological origin. In this study the primary approach which depends on the loading of Curcumin into κ-Carrageenan was accomplished, and which (κ-Car-Cur) an active drug carrier was developed for drug delivery against selected lung cancer cells (A549). Thus, the κ-Car-Cur was synthesized by solvent evaporation method followed by freeze drying, and it was further characterized. From this study, it has been reported that the high encapsulation efficiency, good stability, and successful release of Cur from the carrier (κ-Car) was achieved. The drug release was more active at acidic pH 5.0 with the cumulative release of 78%, which is the favorable condition present in tumor microenvironments. The in vitro cellular applications studies of κ-Car-Cur demonstrated that, κ-Car-Cur composites induced higher cytotoxicity against selected cancer cells than free Cur and effectively involved to trigger cellular apoptosis in A549 cancer cells. Further, it was also possessed that inhibition of cell growth and changes in metabolic activity of cancer cells are the unique characteristic features of cellular apoptosis, through reactive oxygen species (ROS) generation. It also observed that there was a decrease in mitochondrial membrane potential (ΔψmΔψm) which leads to a cellular apoptosis during treatment with κ-Car-Cur. Hence, the study outcomes may provide the potential outline for the use of κ-Car-Cur as a promising tool to deliver drugs at intracellular level.

Synthesis of chitosan capped copper oxide nanoleaves using high intensity (30kHz) ultrasound sonication and their application in antifouling coatings.

The synthesis of chitosan capped copper oxide nanoleaves (CCCO NLs) was carried out under three different reaction conditions viz. 1) room temperature, 2) 70°C and 3) high intensity ultrasound (30kHz) sonication method and it has been found that the high intensity ultrasound (30kHz) sonication is the best method when compared to other two methods. The advantages of the present synthetic method are: i) easy one step process, ii) lesser reaction time, iii) good yield, iv) reproducible and v) calcination is not required. The resulting chitosan capped copper oxide nanoleaves were characterized by Diffuse Reflectance UV-Visible Spectroscopy (DRS), Fourier Transform Infra-Red Spectroscopy (FT-IR), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscopy (HRTEM) and Thermo gravimetric analysis (TGA). The CCCO NLs were blended with commercial paints such as polyurethane clear, polyurethane white and acrylic emulsion and applied on to three different surfaces (wood, mild steel and cement slab panels). The hydrophilicity of CCCONP coated panels was analyzed by water contact angle measurement and their antifouling behavior was investigated against three different green and marine algae viz. Arthrospira, Chlorella and Amphora. The antifouling efficiency of the CCCO NLs against the algae was found to be 78-92%.

Synthesis and characterization of chitosan-g-N-methyl piperazinium chloride: A hybrid flocculant.

Flocculation is one of the most widely applied techniques for water treatment. Flocculants based on natural polymer has received more attention due to their eco-friendliness in recent years. New water soluble N-methyl piperazinium chloride grafted chitosan flocculant (chitosan-g-N-MPC) was successfully synthesized and thoroughly characterized using FTIR, NMR and powder X-ray diffraction analytical techniques. Incorporation of N-MPC enhanced the ionic character of the chitosan backbone and improved its water solubility. The flocculation performance of chitosan-g-N-MPC was tested against bentonite suspension. The flocculation performance of chitosan-g-N-MPC was investigated under various pH conditions. Turbidity and zeta potential measurements were employed to investigate the flocculation behavior of the chitosan-g-N-MPC. The characteristics of the industrial wastewater before and after flocculation were analyzed. The morphology of the polymer and flocs were studied by TEM analysis.

Novel PLGA-based nanoparticles for the oral delivery of insulin.

BACKGROUND: Insulin is the drug therapy for patients with insulin-dependent diabetes mellitus. A number of attempts have been made in the past to overcome the problems associated with the oral delivery of insulin, but with little success. Orally administered insulin has encountered with many difficulties such as rapid degradation and poor intestinal absorption. The potential use of D-α-tocopherol poly(ethylene glycol) 1000 succinate (TPGS)-emulsified poly(ethylene glycol) (PEG)-capped poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) was investigated for sustained delivery of insulin (IS). OBJECTIVE: To investigate the efficacy of TPGS-emulsified PEG-capped PLGA NPs (TPPLG NPs) as a potential drug carrier for the oral delivery of insulin. METHODS: A series of biodegradable low-molecular-weight PLGA (80/20 [PLG4] and 70/30 [PLG6]) copolymers were synthesized by melt polycondensation. The commercial insulin-loaded TPGS-emulsified PEG-capped PLGA NPs (ISTPPLG NPs) were synthesized by water-oil-water emulsion solvent evaporation method. The physical and chemical properties of PLGA copolymers, particle size, zeta potential, and morphology of the NPs were examined. The in vivo studies of ISTPPLG NPs were carried out in diabetic rats by oral administration. RESULTS: The maximum encapsulation efficiency of ISTPPLG6 NPs was 78.6% ± 1.2%, and the mean diameter of the NPs was 180 ± 20 nm. The serum glucose level was significantly (twofold) decreased on treatment with ISTPPLG NPs, and there was a threefold decrease with insulin-loaded PLGA (70/30) NPs when compared to that of free insulin-treated diabetic rats. The results show that the oral administration of ISTPPLG6 NPs is an effective method of reducing serum glucose level for a period of 24 hours. Histopathological studies reveal that ISTPPLG NPs could restore the damage caused by streptozotocin in the liver, kidneys, and pancreas, indicating its biocompatibility and regenerative effects. CONCLUSION: ISTPPLG6 NPs can act as potential drug carriers for the oral delivery of insulin.

One pot green synthesis of Ag, Au and Au-Ag alloy nanoparticles using isonicotinic acid hydrazide and starch.

Gold-silver alloy nanoparticles were synthesized via chemical reduction of varying mole fractions of chloroauric acid (HAuCl4) and silver nitrate (AgNO3) by environmentally benign isonicotinic acid hydrazide (INH) in the presence of starch as a capping agent in aqueous medium. The absorption spectra of Au-Ag nanoparticles show blue shift with increasing silver content indicating the formation of alloy nanoparticles. When the Ag content in the alloy decreases the size of the nanoparticles increases and as a result of which the oxidation potential also increases. The emission maximum undergoes a red shift from 443 to 614 nm. The nanoparticles are monodisperse and spherical with an average particle size of 3-18 nm. The catalytic behavior of alloy nanoparticles indicate that the rate constant for the reduction of 4-nitro phenol to 4-amino phenol increases exponentially from metallic Ag to metallic Au as Au content increases in the Au-Ag alloy nanoparticles.

Gold nanoparticle conjugated PLGA-PEG-SA-PEG-PLGA multiblock copolymer nanoparticles: synthesis, characterization, in vivo release of rifampicin.

A series of succinate linearly linked PLGA-PEG-SA-PEG-PLGA multiblock copolymers were synthesized using direct melt polycondensation and characterized using inherent viscosity, gel permeation chromatography (GPC), FTIR and 1H-NMR spectroscopy techniques. Gold nanoparticles (AuNPs) were synthesized using an as-synthesized citrate-PEG (CPEG) hybrid dendron, which acts as a reducing agent as well as a stabilizing agent. The CPEG capped AuNPs were characterized using UV-visible spectroscopy and TEM analysis. The Au-conjugated PLGA-PEG-SA-PEG-PLGA multiblock copolymer NPs were loaded with the tuberculosis drug rifampicin (RIF) using ultrasonication followed by solvent evaporation and were characterized by TEM, powder XRD and XPS analyses. The RIF loading efficiency and percentage drug content of RIF loaded Au-conjugated multiblock copolymer NPs were evaluated using UV-visible spectroscopy. The RIF loading efficiency and RIF content of the AuNP conjugated multiblock copolymer NPs were 41.8-75.7% and 11.5-17.7% respectively. The in vivo drug release studies in male Wistar rats show that AuNP conjugated multiblock copolymer NPs exhibit drug release up to 240 h. The nanoconjugates exhibit 18.13-29.41 µg mL-1 of Cmax with a delayed Tmax of 72 h and the relative bioavailability is increased to 107-190.

3-Methyl-2-vinyl-pyridinium phosphate.

In the title salt, C8H10N(+)·H2PO4 (-), the cation is essentially planar (r.m.s. deviation = 0.063 Å). In the crystal, the phosphate anions form inversion R 2 (2)(8) dimers via pairs of O-H⋯O hydrogen bonds. These dimers are further linked by pairs of O-H⋯O hydrogen bonds, also enclosing R 2 (2)(8) loops, forming chains running along [001]. The cations are bonded to the anions via N-H⋯O hydrogen bonds and C-H⋯O contacts.

Isoniazid loaded core shell nanoparticles derived from PLGA-PEG-PLGA tri-block copolymers: in vitro and in vivo drug release.

A series of biodegradable low molecular weight PLGA-PEG-PLGA tri-block copolymers have been synthesized in powder form. The anti-tuberculosis drug Isoniazid (INH) loaded polymeric core-shell nanoparticles (CSNPs) have been prepared by sonication followed by water-in-oil-in-water (w/o/w) double emulsification technique. The nanoparticles (NPs) have been characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD) and X-ray photo electron spectroscopic (XPS) techniques. The drug loaded CSNPs were found to be 150-400 nm in size with spherical shape. The drug loading efficiency and drug content of the polymer NPs were determined by UV-vis spectrophotometry. The drug loading efficiency and drug content of the NPs were (12.8-18.67%) and (6.4-8.9%) respectively. The in vitro release behavior of the polymer NPs has been investigated by UV-vis spectrophotometry and the release kinetics mechanism has been evaluated by Korsemeyer-Peppas (KP) and Higuchi models. The in vitro release studies show initial burst release followed by controlled and uniform release for longer duration. The pharmacokinetic studies show that the INH bioavailability of INH loaded CSNPs is 28 fold higher than that of free INH and also the CSNPs show sustained drug release for longer duration.

Synthesis, characterization and electrochemistry of 4'-functionalized 2,2':6',2''-terpyridine ruthenium(II) complexes and their biological activity.

The synthesis and characterization of Ru(II) terpyridine complexes derived from 4'-functionalized 2,2':6',2''-terpyridine ligands by a multi step procedure have been described. The complexes are redox-active, showing both metal-centred (oxidation) and ligand-centred (reduction) processes. The antibacterial and antifungal activity of the synthesized ruthenium(II) complexes [Ru(attpy)2](PF6)2 (attpy = 4'-(4-acryloyloxymethylphenyl)-2,2':6',2''-terpyridine); [Ru(mttpy)2](PF6)2 (mttpy = 4'-(4-methacryloyloxymethylphenyl)-2,2':6',2''- terpyridine); [Ru(mttpy)(MeOPhttpy)](PF6)2 (MeOPhttpy = 4'-(4-methoxyphenyl)-2,2':6',2''-terpyridine); and [Ru(mttpy)(ttpy)](PF6)2 (ttpy = 4'-(4-methylphenyl)-2,2':6',2''-terpyridine) were tested against four human pathogens (Proteus vulgaris, Proteus mirabilis, Pseudomonas aeruginosa and Escherichia coli) and five plant pathogens (Curvularia lunata, Fusarium oxysporum, Fusarium udum, Macrophomina phaseolina and Rhizoctonia solani) by the well diffusion method and MIC values of the complexes are reported. A biological study of the complexes indicated that the complexes [Ru(mttpy)2](PF6)2 and [Ru(mttpy)(MeOPhttpy)](PF6)2 exhibit very good activity against most of the test pathogens and their activity is better than those of some of the commercially available antibiotics like tetracycline and the fungicide carbendazim.