Green Synthesis of Chromium Oxide Nanoparticles for Antibacterial, Antioxidant Anticancer, and Biocompatibility Activities.

This study deals with the green synthesis of chromium oxide (Cr2O3) nanoparticles using a leaf extract of Abutilon indicum (L.) Sweet as a reducing and capping agent. Different characterization techniques were used to characterize the synthesized nanoparticles such as X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), Energy-dispersive X-ray (EDX), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible (UV-VIS) spectroscopy. The X-ray diffraction technique confirmed the purity and crystallinity of the Cr2O3 nanoparticles. The average size of the nanoparticles ranged from 17 to 42 nm. The antibacterial activity of the green synthesized nanoparticles was evaluated against four different bacterial strains, E. coli, S. aureus, B. bronchiseptica, and B. subtilis using agar well diffusion and a live/dead staining assay. The anticancer activities were determined against Michigan Cancer Foundation-7 (MCF-7) cancer cells using MTT and a live/dead staining assay. Antioxidant activity was investigated in the linoleic acid system. Moreover, the cytobiocompatibility was analyzed against the Vero cell lines using MTT and a live/dead staining assay. The results demonstrated that the green synthesized Cr2O3 nanoparticles exhibited superior antibacterial activity in terms of zones of inhibition (ZOIs) against Gram-positive and Gram-negative bacteria compared to plant extracts and chemically synthesized Cr2O3 nanoparticles (commercial), but comparable to the standard drug (Leflox). The green synthesized Cr2O3 nanoparticles exhibited significant anticancer and antioxidant activities against MCF-7 cancerous cells and the linoleic acid system, respectively, compared to chemically synthesized Cr2O3 nanoparticles. Moreover, cytobiocompatibility analysis displayed that they presented excellent biocompatibility with Vero cell lines than that of chemically synthesized Cr2O3 nanoparticles. These results suggest that the green synthesized Cr2O3 nanoparticles' enhanced biological activities might be attributed to a synergetic effect. Hence, green synthesized Cr2O3 nanoparticles could prove to be promising candidates for future biomedical applications.

Facile green synthesis approach for the production of chromium oxide nanoparticles and their different in vitro biological activities.

Green synthesis of nanoparticles using plants has become a promising substitute for the conventional chemical synthesis methods. In the present study, our aim was to synthesize chromium oxide nanoparticles (Cr2 O3 NPs) through a facile, low-cost, eco-friendly route using leaf extract of Rhamnus virgata (RV). The formation of Cr2 O3 NPs was confirmed and characterized by spectroscopic profile of UV-Vis, EDX, FTIR, and XRD analyses. The UV-visible spectroscopy has confirmed the formation of Cr2 O3 NPs by the change of color owing to surface plasmon resonance. The bioactive functional groups present in the leaf extract of RV involved in reduction and stabilization of Cr2 O3 NPs were determined by FTIR analysis. Based on XRD analysis, crystalline nature of Cr2 O3 NPs was determined. The morphological shape and elemental composition of Cr2 O3 NPs were investigated using SEM and EDX analyses, respectively. With growing applications of Cr2 O3 NPs in biological perspectives, Cr2 O3 NPs were evaluated for diverse biopotentials. Cr2 O3 NPs were further investigated for its cytotoxicity potentials against HepG2 and HUH-7 cancer cell lines (IC50 : 39.66 and 45.87 µg/ml), respectively. Cytotoxicity potential of Cr2 O3 NPs was confirmed against promastigotes (IC50 : 33.24 µg/ml) and amastigotes (IC50 : 44.31 µg/ml) using Leishmania tropica (KMH23 ). The Cr2 O3 NPs were further evaluated for antioxidants, biostatic, alpha-amylase, and protein kinase inhibition properties. Biocompatibility assay was investigated against human macrophages which confirmed the nontoxic nature of Cr2 O3 NPs. Overall, the synthesized Cr2 O3 NPs are biocompatible and nontoxic and proved to possess significant biopotentials. In future, different in vivo studies are needed to fully investigate the cytotoxicity and mechanism of action associated with these Cr2 O3 NPs.

Interaction of polypyridyl Cr(III) complexes with bovine serum albumin.

We report a detailed investigation of the interaction of Cr(NN)33+ with bovine serum albumin (BSA), an important protein for the transport of drugs in blood plasma which allows us to understand further the role of Cr(NN)33+ as a sensitizer in photodynamic therapy (PDT). Chromium(III) complexes, Cr(5Cl-phen)33+, Cr(5Me-phen)33+ and Cr(5Ph-phen)33+ (where Cl = chlorine, Me = methyl and Ph = phenyl are substituents in position 5 of the phen = 1,10-phenanthroline bidentate ligand), were used for the present study. The interactions of BSA with Cr(NN)33+ were assessed employing fluorescence spectroscopy and UV-Vis absorption spectroscopy; in addition electrochemical experiments carried out at a liquid/liquid interface gave insight into the relative hydrophobicities of the complexes. We found that chromium complexes bind strongly with bovine serum albumins (BSA) with intrinsic binding constants, Kb, of (3.33 ± 0.08) × 105 M-1, (5.92 ± 0.08) × 105 M-1 and (1.64 ± 0.05) × 105 M-1 at 300.3 K. Analysis of the thermodynamic parameters ΔG, ΔH, and ΔS indicated that hydrophobic interactions played a major role in all the BSA-Cr(NN)33+ association processes. The binding distances and transfer efficiencies for BSA binding reactions were calculated according to the Förster theory of non-radiation energy transfer giving distance (r) of 2.63 nm, 2.94 nm and 3.00 nm for 5Clphen, 5Mephen and 5Ph phenanthroline complexes, respectively. All these experimental results indicate that Cr(NN)33+ binds to serum albumins, by which these proteins could act as carriers of this complex for further applications in PDT.

Preliminary studies of the effect of doping of chromium oxide in SiO2-CaO-P2O5 bioceramics for bone regeneration applications.

Bioceramics of composition xCr2O3∙(43-x) CaO∙42SiO2∙15P2O5 (x varying from 0 to 8 mol%) have been synthesized in the laboratory by using sol-gel technique. The morphology and structure has been determined by using Powder X-ray Diffraction, Fourier Transform Infrared and Raman spectroscopy and Field Emission Scanning Electron Microscopy. The in vitro bio mineralization behavior has been assessed by immersion in simulated body fluid for 7 days. The results obtained in our studies have indicated excellent hydroxyapatite formation ability of our samples. Drug delivery property of synthesized samples has been checked by using UV-spectroscopy of antibiotic 'gentamicin'. The in vitro drug release profile was fitted best in the Higuchi model with the highest value of coefficient of determination (R2 = 0.9970). Antimicrobial properties have been evaluated from minimum inhibitory concentration and time kill assay values. The cellular response has been investigated by using human osteosarcoma MG 63 cell line. Also to check charge on the synthesized samples, Zeta potential studies have been conducted and it has been observed that samples carry negative charge when immersed in simulated body fluid. Negative surface charge provide suitable environment for cell adhesion and proliferation. Experiments have been undertaken to explore suitable composition with an objective of development of suitable implant material for bone regeneration applications.

Ameliorative effect of chromium-d-phenylalanine complex on indomethacin-induced inflammatory bowel disease in rats.

Present study was designed to evaluate the effect of chromium-d-phenylalanine complex (Cr (d-phe)3) on indomethacin-induced inflammatory bowel disease (IBD) in rats. Adult Wistar rats were pretreated with vehicle/Cr (d-phe)3 (30, 60 and 90µg/kg, p.o.) for 11days. On day 8 and 9, after one h of the above mentioned treatment, indomethacin (7.5mg/kg/day,s.c.) was administered to induce IBD. On day 12, blood samples were collected from animals for lactate dehydrogenase (LDH) estimation and ileum was isolated for macroscopic scoring, biochemical estimation (lipid peroxidation, reduced glutathione and myeloperoxidase activity) and histopathological study. Administration of indomethacin significantly altered the serum LDH, macroscopic and microscopic appearance and biochemical parameters in ileum tissue. Cr (d-phe)3, at all the tested doses, caused a significant reversal of changes induced by indomethacin. Present study demonstrates the protective effect of Cr (d-phe)3 against indomethacin-induced IBD in rats. The observed protective effect might be attributed to the antioxidant and anti-inflammatory properties of Cr (d-phe)3.

Effect of Cr(VI) concentration on gas and particle production during iron oxidation in aqueous solutions containing Cl- ions.

Zero-valent iron (ZVI) is commonly used as a medium in permeable reactive barriers (PRBs) because of its high reducing ability. The generation of H2 gas in PRBs, however, can decrease the permeability of PRBs and reduce the contact area between the PRB and contaminated groundwater. This study investigated the effect of the initial Cr(VI) concentration ([Cr(VI)init]) in aqueous solutions containing Cl- ions on the generation of H2 gas. ZVI chips were reacted in reactors with 0.5-M NaCl solutions with [Cr(VI)init] ranging between 51 and 303 mg/L. The initial pH was set at 3. The oxidation of ZVI chips by Cr(VI) in aqueous solutions containing Cl- ions produced H2 gas and particles (Fe(III)-Cr(III)(oxy)hydroxides). The Cr(VI) removal from aqueous solutions increased as the [Cr(VI)init] increased, as did H2 gas generation. The positive effect of [Cr(VI)init] on H2 gas generation might be due to an increase in the redox potential gradient as [Cr(VI)init] increases. This increased gradient would enhance H+ ion penetration through the passive film (Fe(III)-Cr(III)(oxy)hydroxides), which formed on the ZVI surface, by diffusion from the solution to pits beneath the passive film.

Peptide-based biocoatings for corrosion protection of stainless steel biomaterial in a chloride solution.

In this work, PEGylated D-amino acid K122-4 peptide (D-K122-4-PEG), derived from the type IV pilin of Pseudomonas aeruginosa, coated on 304 stainless steel was investigated for its corrosion resistant properties in a sodium chloride solution by various electrochemical measurements, surface characterization and molecular dynamics simulation. As a comparison, stainless steel electrodes coated with non-PEGylated D-amino acid retroinverso peptide (RI-K122-4) and D-amino acid K122-4 peptide (D-K122-4) were used as control variables during electrochemical tests. It was found that the D-K122-4-PEG coating is able to protect the stainless steel from corrosion in the solution. The RI-K122-4 coating shows corrosion resistant property and should be investigated further, while the D-K122-4 peptide coating, in contrast, shows little to no effect on corrosion. The morphological characterizations support the corrosion resistance of D-K122-4-PEG on stainless steel. The adsorption of D-K122-4 molecules occurs preferentially on Fe2O3, rather than Cr2O3, present on the stainless steel surface.

Using Neutron Reflectometry to Discern the Structure of Fibrinogen Adsorption at the Stainless Steel/Aqueous Interface.

Neutron reflectometry has been successfully used to study adsorption on a stainless steel surface by means of depositing a thin steel film on silicon. The film was characterized using XPS (X-ray photoelectron spectroscopy), TOF-SIMS (time-of-flight secondary ion mass spectrometry), and GIXRD (grazing incidence X-ray diffraction), demonstrating the retention both of the austenitic phase and of the required composition for 316L stainless steel. The adsorption of fibrinogen from a physiologically-relevant solution onto the steel surface was studied using neutron reflectometry and QCM (quartz crystal microbalance) and compared to that on a deposited chromium oxide surface. It was found that the protein forms an irreversibly bound layer at low concentrations, with maximum protein concentration a distance of around 20 Å from the surface. Evidence for a further diffuse reversibly-bound layer forming at higher concentrations was also observed. Both the structure of the layer revealed by the neutron reflectometry data and the high water retention predicted by the QCM data suggest that there is a significant extent of protein unfolding upon adsorption. A lower extent of adsorption was seen on the chromium surfaces, although the adsorbed layer structures were similar, suggesting comparable adsorption mechanisms.

Non-invasive topical drug delivery to spinal cord with carboxyl-modified trifunctional copolymer of ethylene oxide and propylene oxide.

In this study the effect of oxidative modification on micellar and drug delivery properties of copolymers of ethylene oxide (EO) and propylene oxide (PO) was investigated. Carboxylated trifunctional copolymers were synthesized in the reaction with chromium(VI) oxide. We found that carboxylation significantly improved the uniformity and stability of polymeric micelles by inhibiting the microphase transition. The cytotoxicity of copolymers was studied in relation to their aggregative state on two cell types (cancer line vs. primary fibroblasts). The accumulation of rhodamine 123 in neuroblastoma SH-SY5Y cells was dramatically increased in the presence of the oxidized block copolymer with the number of PO and EO units of 83.5 and 24.2, respectively. The copolymer was also tested as an enhancer for topical drug delivery to the spinal cord when applied subdurally. The oxidized copolymer facilitated the penetration of rhodamine 123 across spinal cord tissues and increased its intraspinal accumulation. These results show the potential of using oxidized EO/PO based polymers for non-invasive delivery of protective drugs after spinal cord injury.

Organoselenium Small Molecules and Chromium(III) Complexes for Intervention in Chronic Low-grade Inflammation and Type 2 Diabetes.

There is growing evidence to suggest that chronic, low-grade inflammation occurs in abdominal obesity, insulin resistance, type 2 diabetes mellitus and related complications, and that proinflammatory cytokines play an important role in the onset and progression of type 2 diabetes. These findings consequently provide new opportunities for the use of anti-inflammatory strategies to correct the metabolic disorders. Discovery of new synthetic bioactive small molecules to interfere with chronic, low-grade inflammation and type 2 diabetes has attracted considerable attention in medicinal chemistry. To date, a number of organoselenium small molecules and chromium(III) complexes have been shown to have the potential to alleviate chronic low-grade inflammation and type 2 diabetes, including ebselen, selenomethionine, chromium picolinate, chromium dinicocysteinate, chromium phenylalaninate, trinuclear chromium propionate, chromium histidinate, chromium nicotinate, etc. Here, we review recent advances in development of organoselenium small molecules and chromium(III) complexes to intervene in chronic low-grade inflammation and type 2 diabetes, and discuss their mode of action, potential molecular mechanisms and toxicity.

Chromenone-conjugated magnetic iron oxide nanoparticles. Toward conveyable DNA binders.

Magnetic nanoparticles can transport drug and possibly target cancer. DNA-binding of ligands loaded in dextran coated magnetic nanoparticles, could aid their better target-specific binding. In this work, we report the loading of chromenones onto aminoethylamino-modified dextran coated iron oxide nanoparticles, their loading efficiency, and openness for binding to DNA. The magnetic behavior, the size, and the morphology of the nanoparticles are analyzed. The crystallite size of the magnetic nanoparticles is around 40 nm. The chromenones are present on the surface of the dextran shell, as revealed by their cyclodextrin-binding characteristics, which is a new approach in comprehending the accessibility of the surface-bound molecules by macromolecules. The mode of binding of the chromenones to DNA is not altered on surface loading on dextran shell, although the binding strength is generally diminished, compared to the strength of binding of the free chromenones to DNA.

The enrichment of surface passive film on stainless steel during biofilm development in coastal seawater.

The surface passive film on UNS S30400 alloy was characterized before and after biofilm development under different regimes of diurnal lighting in quiescent flowing coastal seawater. As exemplified by atomic force microscopy, the passive film grew under all test conditions with conspicuous variations in morphological features. X-ray photon spectroscopy illustrated an enrichment of the outer film by iron oxide and a progressive increase in the iron oxide/chromium oxide ratio with lighting. Mott-Schottky plots reflected the duplex nature of the film, comprising an outer n-type and an inner p-type configuration. The slopes of the plots showed a strong decrease in donor and acceptor densities with biofilm coverage and lighting, thus confirming passive film growth. These results provide new insights that passive film enrichment is an intrinsic process under practical marine conditions, and show that the evolution of the passive film is a key step to sustained passivity and/or its breakdown by microbial mechanisms.

Raman spectroscopic analysis of iron chromium oxide microspheres generated by nanosecond pulsed laser irradiation on stainless steel.

Iron chromium oxide microspheres were generated by pulsed laser irradiation on the surface of two commercial samples of stainless steel at room temperature. An Ytterbium pulsed fiber laser was used for this purpose. Raman spectroscopy was used for the characterization of the microspheres, whose size was found to be about 0.2-1.7 µm, as revealed by SEM analysis. The laser irradiation on the surface of the stainless steel modified the composition of the microspheres generated, affecting the concentration of the main elemental components when laser power was increased. Furthermore, the peak ratio of the main bands in the Raman spectra has been associated to the concentration percentage of the main components of the samples, as revealed by Energy-Dispersive X-ray Spectroscopy (EDS) analysis. These experiments showed that it is possible to generate iron chromium oxide microspheres on stainless steel by laser irradiation and that the concentration percentage of their main components is associated with the laser power applied.

Oxidation of diesel soot on binary oxide CuCr(Co)-based monoliths.

Binary oxide systems (CuCr2O4, CuCo2O4), deposited onto cordierite monoliths of honeycomb structure with a second support (finely dispersed Al2O3), were prepared as filters for catalytic combustion of diesel soot using internal combustion engine's gas exhausts (O2, NOx, H2O, CO2) and O3 as oxidizing agents. It is shown that the second support increases soot capacity of aforementioned filters, and causes dispersion of the particles of spinel phases as active components enhancing thereby catalyst activity and selectivity of soot combustion to CO2. Oxidants used can be arranged with reference to decreasing their activity in a following series: O3≫NO2>H2O>NO>O2>CO2. Ozone proved to be the most efficient oxidizing agent: the diesel soot combustion by O3 occurs intensively (in the presence of copper chromite based catalyst) even at closing to ambient temperatures. Results obtained give a basis for the conclusion that using a catalytic coating on soot filters in the form of aforementioned binary oxide systems and ozone as the initiator of the oxidation processes is a promising approach in solving the problem of comprehensive purification of automotive exhaust gases at relatively low temperatures, known as the "cold start" problem.

Controlling diabetes by chromium complexes: The role of the ligands.

Diabetes, particularly type II diabetes, is a severe disease condition which affects human health worldwide, with a dramatically increasing trend in Asian countries including China. Currently, no efficient drugs other than those with observable side effects are available. Chromium complexes, with the most known representative chromium picolinate, have been listed as one of most attractive health supplements to attenuate this disease condition in western countries. Recent efforts have been made to develop new chromium complexes with novel ligands. Although fair amounts of reviews have been published to emphasize the biological activity, preclinical and clinical information of chromium picolinate, this mini-review is trying to cover the entire picture of updated research efforts on various chromium complexes highlighting the role of ligands. Chromium phenylalanine sensitizes insulin cell signaling pathway via the activation of phosphorylation of Akt (protein kinase B (PKB)) and/or AMPK (AMP-activated protein kinase). The biological activities, toxicity, pharmacological features and clinical implications, including the effect of anti-oxidative capacities, protective effect on obese-induced heart dysfunction, and efficacy and safety of chromium supplementation in diabetes are discussed as well.

Direct catalytic oxyamination of benzene to aniline over Cu(II) nanoclusters supported on CuCr2O4 spinel nanoparticles via simultaneous activation of C-H and N-H bonds.

We report the facile synthesis of a highly efficient, reusable catalyst comprising Cu(II) nanoclusters supported on CuCr2O4 spinel nanoparticles for the oxyamination of benzene to aniline (H2O2 + NH3) under mild aqueous reaction conditions. The synergy between the Cu(II) nanoclusters and CuCr2O4 spinel nanoparticles plays the most vital role towards its high catalytic activity.

Investigation on the chromium oxide interaction with soluble chromatin and histone H1: a spectroscopic study.

Chromatin has been introduced as a tool for studying heavy metals action in nuclei. Chromium oxide is highly soluble and toxic with chronic exposure leading to mutagenesis and carcinogenesis. In the present study, for the first time, the binding affinity of chromium oxide to rat liver chromatin and histone proteins was investigated. Reduction of chromatin absorbencies at 210 and 260 nm (hypochromicity) and fluorescence emission intensity upon metal binding represented quenching of the metal with chromatin chromophores. Binding isotherms demonstrated a positive cooperative binding pattern revealing higher affinity of the metal to chromatin compared to DNA as confirmed by the binding constants. Melting temperature of chromatin was altered in a dose dependent manner and suggests partial removal of histones from the chromatin at metal concentrations higher than 15 µg/ml. Chromium oxide decreased the absorbance of histone H1 at 210 nm (hypochromicity) and fluorescence emission intensity revealed quenching of the metal with tyrosine residue located in the core domain of H1. Also the interaction of chromium oxide with histone H1 increased its secondary structures. The results suggest toxic effect of very low concentrations of chromium oxide on chromatin and in this reaction both DNA and histones are involved.

In vitro macrophage response to nanometer-size chromium oxide particles.

An increasing number of studies have reported adverse tissue reactions around metal-on-metal (MM) hip implants. However, the origin and mechanisms of these reactions remain unclear. Moreover, the biological effects of nanometer-size chromium oxide particles, the predominant type of wear particles produced by MM implants, remain mostly unknown. The purpose of this study was to analyze the cytotoxic effects of clinically relevant nanometer-size chromium oxide particles on macrophage response in vitro. J774.A1 macrophages were cultured with either 60 nm or 700 nm commercially available Cr2 O3 particles at different concentrations. Two different particle sizes were analyzed to evaluate potential volume effects. Cell mortality was analyzed by light microscopy, flow cytometry (annexin V-fluorescein isothiocyanate and propidium iodide assay), and using a cell death detection enzyme-linked immunosorbant assay (ELISA). Tumor necrosis factor alpha (TNF-α), monocyte chemotactic protein-1 (MCP-1), and macrophage inflammatory protein-1 alpha (MIP-1α) release was measured by ELISA, and gene expression was analyzed by quantitative real-time PCR. Results showed that, at high concentrations, Cr2 O3 particles of both sizes can be cytotoxic, inducing significant decreases in total cell numbers and increases in necrosis. Results also suggested that these effects were dependent on particle volume. However, TNF-α, MCP-1, and MIP-1α cytokine release and gene expression remained low. Overall, this study demonstrates that nanometer-size particles of Cr2 O3 , a stable form of chromium oxide ceramic, have rather low cytotoxic effects on macrophages. Therefore, these particles may not be the main culprit in the initiation of the inflammatory reaction in MM periprosthetic tissues. However, other parameters (e.g., potential intracellular damage) remain to be investigated.

Preliminary study of the biodegradation and the correlation between in vitro and in vivo release of (32)P-chromic phosphate-poly(L-lactide) seeds.

OBJECTIVE: To investigate the drug release kinetic of (32)P-chromic phosphate-poly(L-lactide) ((32)P-CP-PLLA). METHODS: (32)P-CP-PLLA were placed into physiological saline and H22 solid tumor mass, respectively. The weight loss rate and radioactivity release rate were evaluated. The release of the microparticles was evaluated using fitting curves. The correlation of the release of the microparticles between physiological saline and H22 solid tumor mass was analyzed. RESULTS: Close correlation was noted in the release of the microparticles between physiological saline and H22 solid tumor mass. The Weibull equation showed the best fitting of (32)P-CP-PLLA in physiological saline. CONCLUSIONS: The Weibull equation could be used for the predictive release of microparticles in vitro. The parameters obtained from the drug release kinetics could be used to estimate the dose of radiopharmaceuticals within the tumors and the surrounding tissues.

Studies on the genotoxic effect of chromium oxide (Cr VI): interaction with deoxyribonucleic acid in solution.

Chromium is a toxic and carcinogenic compound widely distributed in environment. In the present study we have investigated the interaction of chromium oxide with DNA employing UV/vis and fluorescence spectroscopy as well as Circular dichroism, thermal denaturation, retardation polyacrylamide gel electrophoresis and DNA-cellulose affinity techniques. The results showed that the binding of chromium oxide to DNA is concentration dependent; at low concentration shows a little effect but ant higher concentrations (>100µg/ml) reduced the absorbance at 260 and 210nm producing hypochromicity. Also λ(max) of the metal at 210, 260 and 350nm was reduced. DNA chromophores quenched with the chromium oxide and decreased fluorescence emission intensity. Upon binding of the metal to DNA the elliplicity at positive extreme was decreased (275nm) and increased the ellipticity of the DNA at negative extreme 245nm. Thermal denaturation profile of DNA shifted to higher degrees upon chromium oxide binding which accompanied by hypochromicity. Also, affinity of chromium oxide to double stranded DNA was higher than single stranded DNA. From the result it is concluded that chromium oxide interacts with DNA via two modes of interaction inducing structural changes and DNA compaction evidence providing chromium oxide genotoxicity.