In situ synthesis of iron oxide nanoparticles in a styrene-divinylbenzene copolymer

Summary Magnetic iron oxide nanoparticles were prepared by in situ within a sulfonated styrene-divinylbenzene copolymer. The magnetic nanocomposite was characterized by X-ray diffraction, transmission electron microscopy and vibrating sample magnetometry. The size distribution of the nanoparticles was relatively narrow with good distribution within the copolymer. Nearly spherical nanoparticles, 7 nm in diameter, were identified as CoFe₂O₄ and had a well-defined crystalline structure. Magnetic measurements revealed that the magnetic nanocomposites are superparamagnetic.     

In vitro biosynthesis of prostaglandin E2 by kidney medulla of essential fatty acid deficient rats

Weanling rats were fed either a semi-synthetic diet with no fat, with 28% by wt partially hydrogenated fish oil, or with 28% by wt arachis oil (control diet) for 6 or 71/2 months. The in vitro conversion of arachidonic acid to prostaglandin E₂ by homogenates of the rat kidney medulla was measured by gaschromatography with electron capture detection. The kidney medulla of essential fatty acid deficient animals showed increased activity for the in vitro conversion of exogenous arachidonic acid to prostaglandin E₂ when compared to the controls. The change of the enzymatic activity in the essential fatty acid deficient animals was reversible, as shown by refeeding. Inhibition of the prostaglandin synthetase was found at exogenous substrate concentrations higher than 50–100 μM.     

Anionic polymerization of alkyl cyanoacrylates: In vitro model studies for in vivo applications

Alkyl cyanoacrylates were polymerized anionically in water medium at different levels of pH. The effect of pH on the molecular weight and softening points of the polymers was studied. Alkyl cyanoacrylates were also polymerized in suspension by using the combination of methanol–water, and also by using different catalysts such as triethylamine, diazabicyclooctane, and diazabicycloundecane. The poly(cyanoacrylates) thus obtained were characterised by infrared and nuclear magnetic resonance spectroscopy. The molecular weight, molecular weight distribution, and the softening points of the polymers were determined. These studies would help in more effective usage of cyanoacrylates as bioadhesives under varied physiological conditions. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 336–344, 1999     

Diclofenac-hydrotalcite: In vitro and in vivo release experiments

Solutions of the anti-inflammatory drug diclofenac in ethanol and ethanol–water were prepared and mixed with hydrotalcite and hydrotalcite heated at 500 °C. Hydrotalcite pretreated at 500 °C showed a higher adsorption of diclofenac. Diclofenac-hydrotalcites were used for in vitro release experiments to evaluate the percutaneous absorption of diclofenac, using sets of eight Franz cells with membranes of stratum corneum epidermis obtained from human skin; a 2% diclofenac hydroalcoholic gel was used for comparison. Hydrotalcite pretreated at 500 °C is less suitable for release procedures, despite its higher adsorption capacity, whereas diclofenac adsorbed from ethanolic solution by untreated hydrotalcite presents the most efficient sample and shows the best permeation profiles. This sample was selected for the in vivo experiments. Ten healthy volunteers participated on the in vivo experiments: the diclofenac-hydrotalcite appeared to be useful for an efficient application on human skin as inhibitor of the UV-induced erythemas, also better than the usual gel samples.     

Bioadhesive hydrophobic chitosan microparticles for oral delivery of insulin: In vitro characterization and in vivo uptake studies

Hydrophobically modified polymeric matrices for drug delivery were developed by N‐acylation of chitosan with long(C₁₈) and medium chain(C₈) fatty acid chlorides like octanoyl and oleoyl chloride. Chemical modifications of chitosan were confirmed by IR spectra and trinitrobenzenesulphonic acid assay. Modified chitosan particles were prepared by ionotropic gelation with sodium tripolyphosphate. Hydrophobic modification was confirmed by contact angle measurements. Scanning electron micrographs showed the presence of compact microparticles. Swelling studies showed that oleoyl chitosan exhibited low swelling profile than octanoyl chitosan at acidic pH. In vitro release profile at pH 7.4 showed that about 90% of insulin was released by 5th hour. ELISA studies proved that the microparticles were capable of maintaining biological activity of insulin. Mucoadhesion studies proved that oleoyl derivative was more mucoadhesive than octanoyl derivative. In vivo uptake studies of fluorescent‐labeled microparticles on rat intestinal sections showed that oleoyl chitosan microparticles exhibited significant uptake than octanoyl chitosan. These results suggests that oleoyl moiety would resist degradation by the gastric enzymes and will enhance mucoadhesivity through hydrophobic interactions and also the permeability by loosening the tight junctions, thus making it a useful carrier for oral peptide delivery applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

In vitro and in vivo analysis of antide delivery from multi-phase microspheres fabricated via solvent removal

Antide, a gonadotropin releasing hormone (GnRH) antagonist, has been studied as a new drug for treatment of various gonadotropin-dependent disorders, including hormone-dependent prostate and breast cancer. Antide was encapsulated into multi-phase microspheres composed of poly(l-lactic)acid (PLLA) and poly(fumaric-co-sebacic)anhydride (P(FA:SA)) fabricated via solvent removal and loaded at 5% and 20% (w/w). In vitro release kinetics and the in vivo therapeutic effect (changes in the testosterone levels) were evaluated. In vivo studies were conducted in male rats at a dose of 12.5 mg antide/kg for both the 5% and 20% loaded particles as well as 31.5 mg antide/kg for the 20% loaded particles. The 5% loaded particles achieved a decrease in testosterone levels below the castration level (0.5 ng/mL) over the course of 11 weeks. The 20% loaded particles resulted in testosterone levels below the castration level for 7 weeks. The results of these studies demonstrate that it is possible to encapsulate antide into a controlled delivery system for more than 2 months. Furthermore, we were able to achieve a therapeutic response in vivo indicated by serum testosterone levels below the castration level of 0.5 ng/mL for at least 11 weeks.     

The synthesis of barium hexaferrite from iron oxide and barium carbonate: II. The role of iron oxide texture

The texture of several samples of laboratory-prepared and commercial iron oxide and their reactivity with barium carbonate (BaCO₃.6Fe₂O₃) has been examined. The first stage of the reaction involves decarbonation with the formation of monoferrite and dynamic thermogravimetry was used to assess mix reactivity. While some of the variation in the behaviour of iron oxide powders could be appreciated from an examination of their texture by scanning electron microscopy and porosity determination, prediction of their reactivity was not possible. In fact the reactivity of the mix can best be considered to give an indication of the efficiency of mixing of the finer iron oxide particles with the barium carbonate. In the subsequent formation of barium hexaferrite the coarse end of the iron oxide particle size range is of primary importance since it controls the rate of completion of the reaction. The larger aggregates in an iron oxide sample can readily be detected by scanning electron microscopy but conclusions regarding reactivity may be erroneous if this coarse material is dispersed during mixing. It was shown by scanning electron microscopy that the least reactive iron oxide sample examined contained aggregates which survived the mixing process employed.     

In vitro and in vivo behaviors of dextran functionalized graphene

Development of biocompatible surface coating is critical to engineer various functional nanomaterials for biomedical applications. Here, we present a new surface chemistry of graphene by covalently conjugating graphene oxide (GO) with dextran (DEX), a biocompatible polymer widely used for surface coating of biomaterials. Compared with GO, the graphene–dextran (GO–DEX) conjugate shows reduced sheet sizes, increased thickness and significantly improved stability in physiological solutions. Cellular experiments uncover that DEX coating on GO offers remarkably reduced cell toxicity. We further label GO–DEX with a radioactive isotope, ¹²⁵I, for in vivo tracking in animal studies. It is found that GO–DEX accumulates in the reticuloendothelial system (RES) including liver and spleen after intravenous injection, and importantly, shows obvious clearance from the mouse body within a week without causing noticeable short-term toxicity to the treated animals. Our results suggest that this DEX coating method on GO may potentially be useful to the further development of novel graphene-based bioconjugates for various biomedical applications.     

Kinetic studies on the reactions involved in the hot gas desulfurization using a regenerable iron oxide sorbent—I: Reduction and sulfidation of iron oxide

The reactions of iron oxide (45 wt.% Fe₂O₃, 55 wt.% SiO₂) with a hot gas containing H₂, CO and H₂S were investigated over a temperaThe data are correlated using the grain model. The intrinsic rate constants are obtained from the data on the reactions of smallest particles at low co     

In vivo and in vitro lipid accumulation inBorago officinalis L.

Seeds of 13 accessions of borage (Borago officinalis) varied in total fatty acid content from 28.6 to 35.1% seed weight, with linoleic, γ-linolenic, oleic and palmitic as the predominant fatty acids, averaging 38.1%, 22.8%, 16.3% and 11.3% of total fatty acids, respectively. There was an inverse relation between γ-linolenic acid (25.0 to 17.6%) and oleic acid (14.5 to 21.3%). Fatty acid content of leaf tissues was 9.1% dry weight, with α-linolenic acid 55.2% and γ-linolenic acid 4.4% of total fatty acids. Cotyledons were the major source of fatty acids in seeds. Seed fatty acid content increased from <1 mg at six days postanthesis to about seven mg at maturity (22 to 24 days). Individual fatty acid content of seed was relatively constant after day 8. When immature embryos from 6 to 16 days postanthesis were cultured in a liquid or semisolid basal medium, fatty acid composition was similar to that of in vivo-grown seeds. Growth of cultured embryos decreased as sucrose concentration was increased from 3 to 20% in the basal medium, and most embryos did not survive 30% sucrose; fatty acid as a percentage of dry weight was maximal at 6% sucrose.     

Freeze-drying of liposomal nanohybrid cerasomes with cryoprotectants: In vitro and in vivo evaluation

Liposomal nanohybrid cerasomes as a new type of drug carrier has been widely applied in the controlled release of drugs. However, such vesicles containing polysiloxane networks on the surface were liable to aggregate during the process of freeze-drying for routine storage. To solve this problem, several previously reported cryoprotectants including sucrose, mannitol, sodium alginate, and glucose were chosen for protecting the 10-hydroxycamptothecin-loaded liposomal nanohybrid cerasomes (The drug encapsulation efficiency was of 67.31?±?7.42% and the drug loading content was of 6.73?±?0.74%.) in freeze-drying process. It was found that liposomal nanohybrid cerasomes treated with mannitol can be well dispersed, and the results of particle size and zeta potential showed that the drug-loaded vesicles were well protected with mannitol. In vitro drug release and in vivo pharmacokinetic study showed that the optimal addition amount of mannitol was twice the mass of the drug-loaded vesicles, whereby the cumulative release profile and the pharmacokinetic parameters were similar in the freeze-dried and fresh vesicles.     

In vivo synthesis of nanomaterials in plants: location of silver nanoparticles and plant metabolism

Metallic nanoparticles (MeNPs) can be formed in living plants by reduction of the metal ions absorbed as soluble salts. It is very likely that plant metabolism has an important role in MeNP biosynthesis. The in vivo formation of silver nanoparticles (AgNPs) was observed in Brassica juncea, Festuca rubra and Medicago sativa. Plants were grown in Hoagland''s solution for 30 days and then exposed for 24 h to a solution of 1,000 ppm AgNO₃. In the leaf extracts of control plants, the concentrations of glucose, fructose, ascorbic acid, citric acid and total polyphenols were determined. Total Ag content in plant fractions was determined by inductively coupled plasma atomic emission spectroscopy. Despite the short exposure time, the Ag uptake and translocation to plant leaves was very high, reaching 6,156 and 2,459 mg kg⁻¹ in B. juncea and F. rubra, respectively. Ultrastructural analysis was performed by transmission electron microscopy (TEM), and AgNPs were detected by TEM X-ray microanalysis. TEM images of plant fractions showed the in vivo formation of AgNPs in the roots, stems and leaves of the plants. In the roots, AgNPs were present in the cortical parenchymal cells, on the cell wall of the xylem vessels and in regions corresponding to the pits. In leaf tissues, AgNPs of different sizes and shapes were located close to the cell wall, as well as in the cytoplasm and within chloroplasts. AgNPs were not observed in the phloem of the three plant species. This is the first report of AgNP synthesis in living plants of F. rubra. The contents of reducing sugars and antioxidant compounds, proposed as being involved in the biosynthesis of AgNPs, were quite different between the species, thus suggesting that it is unlikely that a single substance is responsible for this process.

MSC 2010

92 Biology and other natural sciences; 92Cxx Physiological, cellular and medical topics; 92C80 Plant biology     

In vivo and in vitro antilipolytic effects of some various substituted homocysteine-thiolactone-nicotinamides: Structure-activity study

The antilipolytic activity of homocysteine-thiolactone-nicotinamide (ST22) and its 2-chloro (ST71), 6-chloro (ST82) and 6-hydroxy (ST90) derivatives was investigated by evaluation of serum free fatty acids (FFA) and triglycerides (TG) (in vivo) and FFA release from adipose tissue (in vitro). Increased FFA levels in 17-hr fasted rats at 60 min following treatment with 7·10⁻⁴ mol kg⁻¹ p.o. were reduced by 70% (ST22), 60% (ST82) and 18% (ST71), whereas ST90 provoked no change; TG levels showed similar changes. Basal FFA release from epididymal rat adipose tissue at 60 min following treatment with 7·10⁻⁴ mol kg⁻¹ p.o. of ST22 and ST82 was reduced by 79 and 45%, respectively. Lipid mobilization induced by noradrenaline (NA) was diversely affected by the compounds according to the tests employed: with in vivo experiments, serum FFA levels were reduced by 60, 70, 10 and 5% at 60 min following treatment with ST22, ST82, ST71 and ST90, respectively (7·10⁻⁴ mol kg⁻¹ p.o.; NA bitartrate, 2 mg kg⁻¹ s.c.); in vitro, ST22 produced no change, whereas the other compounds induced a significant mobilization of FFA. The results suggest that: (a) antilipolytic activity can be greatly modified when various substituents capable of influencing either the inductive (-I) or the resonance (+M) effect are introduced into the different positions of the pyridine ring; and (b) the lipolysis experiments did not evince any direct relationship between the effects obtained by the in vivo tests and those obtained by the in vitro tests.     

Optimized dispersion of nanoparticles for biological in vitro and in vivo studies

Background

The aim of this study was to establish and validate a practical method to disperse nanoparticles in physiological solutions for biological in vitro and in vivo studies.

Results

TiO₂ (rutile) dispersions were prepared in distilled water, PBS, or RPMI 1640 cell culture medium. Different ultrasound energies, various dispersion stabilizers (human, bovine, and mouse serum albumin, Tween 80, and mouse serum), various concentrations of stabilizers, and different sequences of preparation steps were applied. The size distribution of dispersed nanoparticles was analyzed by dynamic light scattering and zeta potential was measured using phase analysis light scattering. Nanoparticle size was also verified by transmission electron microscopy. A specific ultrasound energy of 4.2 × 10⁵ kJ/m³ was sufficient to disaggregate TiO₂ (rutile) nanoparticles, whereas higher energy input did not further improve size reduction. The optimal sequence was first to sonicate the nanoparticles in water, then to add dispersion stabilizers, and finally to add buffered salt solution to the dispersion. The formation of coarse TiO₂ (rutile) agglomerates in PBS or RPMI was prevented by addition of 1.5 mg/ml of human, bovine or mouse serum albumin, or mouse serum. The required concentration of albumin to stabilize the nanoparticle dispersion depended on the concentration of the nanoparticles in the dispersion. TiO₂ (rutile) particle dispersions at a concentration lower than 0.2 mg/ml could be stabilized by the addition of 1.5 mg/ml albumin. TiO₂ (rutile) particle dispersions prepared by this method were stable for up to at least 1 week. This method was suitable for preparing dispersions without coarse agglomerates (average diameter < 290 nm) from nanosized TiO₂ (rutile), ZnO, Ag, SiO_x, SWNT, MWNT, and diesel SRM2975 particulate matter.

Conclusion

The optimized dispersion method presented here appears to be effective and practicable for preparing dispersions of nanoparticles in physiological solutions without creating coarse agglomerates.     

Triphenyltin ortho-aminophenyl- and 2-pyridyl-thiolates: synthesis and in vitro antitumour activity

The synthesis, spectroscopic characterization and in vitro antitumour activity of two triorganotin compounds, triphenyltin ortho-aminophenylthiolate (1) and triphenyltin 2-pyridylthiolate, compound (2) are reported. The structure of 1 is confirmed by X-ray diffraction, with the tin atom in a distorted tetrahedral geometry because of monodentate coordination, as a thiolate (Sn-S 2.431(2) A), of the ortho-aminophenylthiolate ligand. The in vitro antitumour activities of 1 and 2, against a number of cell lines, are comparable to those exhibited by methotrexate and doxorubicin, and higher than those of carboplatin and cisplatin.     

Controlled release of curcumin from thiolated starch-coated iron oxide magnetic nanoparticles: An in vitro evaluation

Thiolated starch-coated iron oxide nanoparticles containing curcumin were developed to investigate their cytotoxicity on lymphocytes and cancer cell lines. These nanoparticles were prepared using different concentrations of thiolated starch to study the effect of polymer coating on various properties of nanoparticles, namely, yield percentage, particle size, drug encapsulation, etc. Zeta potential confirmed the stability of nanoparticles. The nanoparticles with 5% polymer coating showed drug encapsulation efficiency up to 78%, while loading efficiency was higher than 80%. The cytotoxicity assay revealed excellent compatibility of the system with lymphocyte cells while considerable amount of cytotoxicity on cancer cell lines.