Immobilization of Ibuprofen-Containing Nanospheres in Layer-by-Layer Films

Liposomes have been applied to many fields as nanocarriers, especially in drug delivery as active molecules may be entrapped either in their aqueous interior or onto the hydrophobic surface. In this paper we describe the fabrication of layer-by-layer (LbL) films made with liposomes incorporating the anti-inflammatory ibuprofen. The liposomes were made with dipalmitoyl phosphatidyl choline (DPPC), dipalmitoyl phosphatidyl glycerol (DPPG) and palmitoyl oleoyl phosphatidyl glycerol (POPG). LbL films were assembled via alternate adsorption of the polyamidoamine dendrimer (PAMAM), generation 4, and liposomes containing ibuprofen. According to dynamic light scattering measurements, the incorporation of ibuprofen caused DPPC and DPPG liposonnes to become more stable, with a decrease in diameter from 140 to 74 nm and 132 to 63 nm, respectively. In contrast, liposomes from POPG became less stable, with an increase in size from 110 to 160 nm after ibuprofen incorporation. These results were confirmed by atomic force microscopy images of LbL films, which showed a large tendency to rupture for POPG liposomes. Film growth was monitored using nanogravimetry and UV-Vis spectroscopy, indicating that growth stops after 10 bilayers. The release of ibuprofen obtained with fluorescence measurements was slower for the liposomes, with decay times of 9.2 and 8.5 h for DPPG and POPG liposomes, respectively, than for the free drug with a decay time of 5.2 h. Ibuprofen could also be released from the LbL films made with DPPG and POPG liposomes, which is promising for further uses in patches.

Structure, processing and midgut secretion of putative peritrophic membrane ancillary protein (PMAP) from Tenebrio molitor larvae

A cDNA coding for a Tenebrio molitor midgut protein named peritrophic membrane ancillary protein (PMAP) was cloned and sequenced. The complete cDNA codes for a protein of 595 amino acids with six insect-allergen-related-repeats that may be grouped in A (predicted globular)- and B (predicted nonglobular)-types forming an ABABAB structure. The PMAP-cDNA was expressed in Pichia pastoris and the recombinant protein (64 kDa) was purified to homogeneity and used to raise antibodies in rabbits. The specific antibody detected PMAP peptides (22 kDa) in the anterior and middle midgut tissue, luminal contents, peritrophic membrane and feces. These peptides derive from PMAP, as supported by mass spectrometry, and resemble those formed by the in vitro action of trypsin on recombinant PMAP. Both in vitro and in vivo PMAP processing seem to occur by attack of trypsin to susceptible bonds in the coils predicted to link AB pairs, thus releasing the putative functional AB structures. The AB-domain structure of PMAP is found in homologous proteins from several insect orders, except lepidopterans that have the apparently derived protein known as nitrile-specifier protein. Immunocytolocalization shows that PMAP is secreted by exocytosis and becomes entrapped in the glycocalyx, before being released into midgut contents. Circumstantial evidence suggests that PMAP-like proteins have a role in peritrophic membrane type 2 formation. (C) 2007 Elsevier Ltd. All rights reserved.

PVP superabsorbent nanogels

Monomer free hydrogel nanoparticles (nanogels) were prepared by crosslinking preformed poly(N-vinyl-2-pyrrolidone) (PVP) entrapped in the aqueous pool of hexadecyltrimethylammonium bromide reverse micelles using the Fenton reaction. The PVP nanoparticles were spherical with a dry diameter of 27 nm. The diameter of the swollen particles was ten times higher, i.e., a swelling ratio, Q, above 900, characterizing this preparation as superabsorbent. PVP nanogel swelling was dependent on bound Fe(3+) and varied with pH and ionic strength. Nanogel deswelling by salt followed the anions lyotropic series, i.e., SCN(-) < HSO(3)(-) < NO(3)(-) < I(-) < Cl(-) < CH(3)COO(-) < CF(3)SO(3)(-). The value of Q reached 6,000 in iron-free PVP nanoparticles at low pH, making this nanogel one of the most efficient swelling systems so far described.

Thermal behavior and stability of biodegradable spray-dried microparticles containing triamcinolone

Thermal analysis has been widely used for obtaining information about drug-polymer interactions and for pre-formulation studies of pharmaceutical dosage forms. In this work, biodegradable microparticles Of Poly (D,L-lactide-co-glycolide) (PLGA) containing triamcinolone (TR) in various drug:polymer ratios were produced by spray drying. The main purpose of this study was to study the effect of the spray-drying process not only on the drug-polymer interactions but also on the stability of microparticles using differential scanning calorimetry (DSC), thermogravimetry (TG) and derivative thermogravimetry (DTG), X-ray analysis (XRD), and infrared spectroscopy (IR). The evaluation of drug-polymer interactions and the pre-formulation studies were assessed using the DSC, TG and DTG, and IR. The quantitative analysis of drugs entrapped in PLGA microparticles was performed by the HPLC method. The results showed high levels of drug-loading efficiency for all used drug: polymer ratio, and the polymorph used for preparing the microparticles was the form B. The DSC and TG/DTG profiles for drug-loaded microparticles were very similar to those for the physical mixtures of the components. Therefore, a correlation between drug content and the structural and thermal properties of drug-loaded PLGA microparticles was established. These data indicate that the spray-drying technique does not affect the physico-chemical stability of the microparticle components. These results are in agreement with the IR analysis demonstrating that no significant chemical interaction occurs between TR and PLGA in both physical mixtures and microparticles. The results of the X-ray analysis are in agreement with the thermal analysis data showing that the amorphous form of TR prevails over a small fraction of crystalline phase of the drug also present in the TR-loaded microparticles. From the pre-formulation studies, we have found that the spray-drying methodology is an efficient process for obtaining TR-loaded PLGA microparticles. (C) 2008 Elsevier B.V. All rights reserved.

Synthesis and structure of 1,3,5-tris(diorganohydroxysilyl)benzenes. Novel building blocks in supramolecular silanol chemistry

The 1,3,5-tris(diorganohydroxysilyl)benzenes 1,3,5-(HOR₂Si)₃C₆H₃ (TMSB, R = Me; TPSB, R = Ph) have been prepared and fully characterized by X-ray crystallography. The crystal structure of TMSB features pairwise connected layers, in which the molecules are involved in interlayer hydrogen bonding. The supramolecular hydrogen bond motif may be described as a 12-membered ring that adopts a chair conformation. TPSB forms an equimolar inclusion complex with water, which is associated via hydrogen bonding and apparently fills a void in the crystal packing. In this case, the supramolecular hydrogen bond motif may be described as an eight-membered ring. Two of the water molecules are also associated, giving rise to a water dimer entrapped in the silanol matrix. Besides the hydrogen bonds, the crystal structure of the TPSB·H₂O complex reveals intra- and intermolecular C-H··· π stacking of most of the phenyl groups. Electrospray mass spectrometry shows that TPSB undergoes supramolecular complex formation with a variety of N-donors such as 4-(dimethylamino)pyridine, N,N,N',N'-tetramethylethylenediamine, imidazole, 2-(dimethylamino)pyridine, and 2,2'-dipyridylamine.

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One-step purification and immobilization of his-tagged rhamnosidase for naringin hydrolysis

α-l-Rhamnosidase (EC 3.2.1.40) is an enzyme that catalyzes the cleavage of terminal rhamnoside groups from naringin to prunin and rhamnose. In this study, a His-tag was genetically attached to the rhamnosidase gene ramA from Clostridium stercorarium to facilitate its purification from Escherichia coli BL21 (DE3) cells containing the pET-21d/ramA plasmid. Immobilized metal-chelate affinity chromatography (IMAC) resulted in one-step purification of N-terminally His-tagged recombinant rhamnosidase (N-His-CsRamA) which was immobilized in Ca²⁺ alginate (3%) beads. The optimum pH levels of the free and immobilized recombinant rhamnosidase were found to be 6.0 and 7.5, and the optimum temperature 55 and 60 °C respectively. At 50 °C, the free enzyme was relatively stable and exhibited a less than 50% reduction in residual activity after 180 min of incubation. The free and immobilized enzymes achieved 76% and 67% hydrolysis of the naringin in Kinnow juice respectively. Immobilization of recombinant rhamnosidase enabled its reutilization up to 9 hydrolysis batches without an appreciable loss in activity. This result indicated that the His-tagged thermostable rhamnosidase could be prepared as described and may serve to illustrate an economical and commercially viable process for industrial application.

Postmodernist-feminism and education : a textual performance

This dissertation is performed as a self-reflexive postmodernist-feminist text that is rather like a work in progress. The relationship between feminismS and postmodernismS is investigated to reveal some of the possibilities that might result from their conjunction, whilst some critical disjunctions which may need to be bridged are recognised. Throughout this dissertation, I have explored how, as well as challenging traditional paradigms of gender, postmodernist-feminism acts to challenge traditional views of meaning, knowledge and text, and, further, how this challenge opens up possibilities for all those entrapped by the paradigms of power, whether outside or Inside. When 'reality' and 'knowledge' are revealed as constructions (not unlike fiction), new possibilities of/for postmodernist-feminist multilinearity emerge. This text practises, then, what I have nominated as three important areas of postmodernist-feminism: jouissance (pleasure and playfulness as in feminist poetics); bricolage (making the text work as a one-off); and deconstruction (an admission that the text is neither seamless nor AUTHORitative). In doing so, it emphasises the practice of what Roland Barthes calls 'writerly-reading', in which the reader is revealed as having power over the text according to the way(s) s/he enters it. In this praxis I suggest that the writer may also abdicate AUTHORity over the text by what I have called 'readerly-writing'. Taking up Gregory Ulmer's challenge to construct a 'mystory', it is my story of my journey as a woman, parent, writer mid teacher who is becoming a certified scholar. My lifelong practical interest in education thus reaches a theoretical self-understanding in this text, which is itself a praxis. Thus I introduce the practice of a non-seamless horizontality in which reflections and stories show themselves to be temporal and cultural constructions. The implications of this for school/educational experiences are central to this praxis.

Immobilization of bacterial recombinant proteins

Recombinant α-L Rhamnosidase has several potential applications in citrus fruit juice processing industries. Immobilized recombinant α-L Rhamnosidase further provides an added advantage to this industrially important enzyme. Various techniques have been used to immobilize native rhamnosidase from fungal origin and applications were explored in great details by several workers. (Puri et al., 1996, 2000, 2001)

A recombinant rhamnosidase from a bacterial source was expressed in E.coli has been immobilized in calcium alginate beads (entrapment method). A batch bioreactor was created for the hydrolysis of naringin using immobilized recombinant α-L Rhamnosidase under shaking and stationary conditions and it was found to hydrolyze naringin effectively. The system was efficient to hydrolyze narigin under shaking conditions and was operationally stable up to 9 days. A high percent hydrolysis of naringin was achieved at pH 7.5 and 60˚C by immobilized rhamnosidase. Entrapped rhamnosidase was able to hydrolyze naringin content in kinnow juice repeatedly and this feature makes this technique economically suitable for debittering of fruit juices.

Pressurized internal lenticular cracks at healed mica interfaces

The equilibrium states of internal penny cracks at interfaces in thin-sheet bodies are investigated. Consideration is given to cracks held open by a center-loading force from an entrapped particle in combination with a uniform pressure from a fixed mass of entrapped gas. A fracture mechanics analysis indicates that under these conditions the cracks are stable, but are amenable to growth from an enhancement in net pressure (increase in internal pressure or decrease in external pressure) or effective particle size. Essential details of the theory are confirmed by experiments on lenticular cracks at healed interfaces in muscovite mica. The results are pertinent to flaw responses in brittle ceramic systems where structural integrity is an issue.

Monte Carlo calculations of the free energy of binary SII hydrogen clathrate hydrates for identifying efficient promoter molecules

The thermodynamics of binary sII hydrogen clathrates with secondary guest molecules is studied with Monte Carlo simulations. The small cages of the sII unit cell are occupied by one H2 guest molecule. Different promoter molecules entrapped in the large cages are considered. Simulations are conducted at a pressure of 1000 atm in a temperature range of 233?293 K. To determine the stabilizing effect of different promoter molecules on the clathrate, the Gibbs free energy of fully and partially occupied sII hydrogen clathrates are calculated. Our aim is to predict what would be an efficient promoter molecule using properties such as size, dipole moment, and hydrogen bonding capability. The gas clathrate configurational and free energies are compared. The entropy makes a considerable contribution to the free energy and should be taken into account in determining stability conditions of binary sII hydrogen clathrates.

Graphene nanodots-encaged porous gold electrode fabricated via ion beam sputtering deposition for electrochemical analysis of heavy metal ions

All rights reserved. A graphene nanodots-encaged porous gold electrode via ion beam sputtering deposition (IBSD) for electrochemical sensing is presented. The electrodes were fabricated using Au target, and a composite target of Al and graphene, which were simultaneously sputtered onto glass substrates by Ar ion beam, followed with hydrochloric acid corrosion. The as-prepared graphene nanodots-encaged porous gold electrodes were then used for the analysis of heavy metal ions, e.g. Cu2+ and Pb2+ by Osteryoung square wave voltammetry (OSWV). These porous electrodes exhibited enhanced detection range for the heavy metal ions due to the entrapped graphene nanodots in 3-D porous structure. In addition, it was also found that when the thickness of porous electrode reached 40 nm the detection sensitivity came into saturation. The linear detection range is 0.009-4 μM for Cu2+ and 0.006-2.5 μM for Pb2+. Good reusability and repeatability were also observed. The formation mechanism and 3-D structure of the porous electrode were also investigated using scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray photoelectron spectra (XPS). This graphene entrapped 3-D porous structure may envision promising applications in sensing devices.

Alasdair Gray`s 1982 Janine (1984): a postmodernist scottish novel

Alasdair Gray is now an established figure in the Scottish literary scene and has numerous claims to be considered an important voice writing in English. First Lanark: A Life in Four Books (1981) and then 1982 Janine (1984) contributed to the recognition of Gray as one of the founding fathers of the new Scottish writing and as a figure of importance in international contemporary fiction due to his innovative, experimental and postmodernist novels. As the title of this dissertation - “Alasdair Gray’s 1982 Janine (1984): A Postmodernist Scottish Novel” - suggests, it aims at analysing the author’s second novel, 1982 Janine (1984), in a thematic and formal perspective, in order to justify the choice of the terms - Postmodernist and Scottish - to classify this novel. 1982 Janine projects a world through Jock McLeish’s mind and is a powerful stream-of-consciousness narrative. Jock is an alcoholic who lives a personal crisis and, therefore, tries to escape from his depressing reality through sexual fantasies and political diatribes. During a single night in a Scottish hotel room, he drinks and dreams, and spends the whole night alone with his fantasies and fears, his memories and hopes. In Chapter 11, the most daring experimental section of the novel, Jock attempts to commit suicide by taking an overdose of tablets with alcohol but fails. Following this, he decides to review his life and make for a new beginning; the novel thus closing with an optimistic note. Also, the narrative is based on a constant interweaving of sex fantasy with political satire, that is, it is through his protagonist that Gray manages to convey the state of Scotland as well as the concerns and aspirations of the Scottish people and then, proceed to a political and social critique. This dissertation appears structured in three chapters. In Chapter I - “Alasdair Gray: A Postmodernist Scottish Writer” - I present Gray as a powerful postmodernist writer who also sees himself as a Scottish author, and more particularly as a Glaswegian, who concentrates on Scottish subject matter in his literary work. In a first section, I offer a brief survey of the Scottish literary scene from the fourteenth to the twentieth century, in order to understand Gray’s choice of setting and themes and to check his influence or indebtedness to previous Scottish authors. As 1982 Janine is also a good example of selfconscious experimental writing, in a second section, I present various seminal fictional works that introduced and developed experimentalism in British fiction, in order to evaluate the influence of modernist developments in form and technique on recent experimental writing. The third section consists of an introduction to Gray’s work for he is not only a novelist, but also an artist, a playwright, a poet, an activist and a scholar. Chapter II - “Postmodernist Features in 1982 Janine” - aims at listing and examining the postmodernist devices that the novel includes, in what content and form are concerned. On the one hand, the use of a developed type of the modernist stream of consciousness, the presence of a protagonist who feels entrapped in a specific system, the quest for freedom, the incoherence and fragmentation of time, the nonchronological order of the narrative, the blending of fantasy and “reality”, as well as the importance of the Scottish material are definitely current aspects within postmodernist literature that can be found in Gray’s novel. On the other hand, the handling of literary self-conscious devices, such as typographical experimentation, presence of metafiction and intertextuality, and inclusion of an Epilogue, are likewise among recurrent postmodernist features. As the title - “A Narratological Analysis of 1982 Janine” - evidences, Chapter III offers a description of the mechanics of the narrative and its functioning in order to better understand the narrative technique of postmodernist fiction. This study is based primarily on Gérard Genette’s theoretical framework and terminology, presented in Narrative Discourse: An Essay in Method, an analytical tool that allows me to provide a more objective and scientific analysis. Hence, I follow the Genettian division of narrative discourse in Time, Mood and Voice while examining the novel. Finally, I proceed to a description of the intertextual relationships 1982 Janine establishes with other texts.

Efeito da incorporação de diatomita na estabilidade e permeabilidade de compósitos cimentíceos espumados aplicados a poços de petróleo

Lightweight oilwell cement slurries have been recently studied as a mean to improve zonal isolation and sheath-porous formation adherence. Foamed slurries consisting of Portland cement and air-entraining admixtures have become an interesting option for this application. The loss in hydrostatic pressure as a consequence of cement hydration results in the expansion of the air bubbles entrapped in the cement matrix, thus improving the sheath-porous formation contact. Consequently, slurries are able to better retain their water to complete the hydration process. The main objective of the present study was to evaluate the effect of the addition of an air-entraining admixture on the density, stability and permeability of composite slurries containing Portland cement and diatomite as light mineral load. Successful formulations are potential cementing materials for low fracture gradient oilwells. The experimental procedures used for slurry preparation and characterization were based on the American Petroleum Institute and ABNT guidelines Slurries containing a pre-established concentration of the air-entraining admixture and different contents of diatomite were prepared aiming at final densities of 13 to 15 lb/gal. The results revealed that the reduction of 15 to 25% of the density of the slurries did not significantly affect their strength. The addition of both diatomite and the air-entraining admixture increased the viscosity of the slurry providing better air-bubble retention in the volume of the slurry. Stable slurries depicted bottom to top density variation of less than 1.0 lb/gal and length reduction of the stability sample of 5.86 mm. Finally, permeability coefficient values between 0.617 and 0.406 mD were obtained. Therefore, lightweight oilwell cement slurries depicting a satisfactory set of physicochemical and mechanical properties can be formulated using a combination of diatomite and air-entraining admixtures for low fracture gradient oilwells

Vertical distribution of benthic invertebrate larvae during an upwelling event along a transect off the tropical Brazilian continental margin

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Micropartículas de poli (ácido lático-co-ácido glicólico) obtidas por spray drying para a liberação prolongada de metotrexato

Methotrexate (MTX) is a drug used in the chemotherapy of some kind of cancers, autoimmune diseases and non inflammatory resistant to corticosteroids uveits. However, the rapid plasmatic elimination limits its therapeutic success, which leads to administration of high doses to maintain the therapeutic levels in the target tissues, occurring potential side effects. The aim of this study was to obtain spray dried biodegradable poly-lactic acid co-glycolic acid (PLGA) microparticles containing MTX. Thus, suitable amounts of MTX and PLGA were dissolved in appropriate solvent system to obtain solutions at different ratios drug/polymer (10, 20, 30 and 50% m/m). The physicochemical characterizing included the quantitative analysis of the drug using a validate UV-VIS spectrophotometry method, scanning electron microscopy (SEM), infrared spectrophotometry (IR), thermal analyses and X-ray diffraction analysis. The in vitro release studies were carried out in a thermostatized phosphate buffer pH 7.4 (0.05 M KH2PO4) medium at 37°C ± 0.2 °C. The in vitro release date was subjected to different kinetics release models. The MTX-loaded PLGA microparticles showed a spherical shape with smooth surface and high level of entrapped drug. The encapsulation efficiency was greater then 80%. IR spectroscopy showed that there was no chemical bond between the compounds, suggesting just the possible occurrence of hydrogen bound interactions. The thermal analyses and X-ray diffraction analysis shown that MTX is homogeneously dispersed inside polymeric matrix, with a prevalent amorphous state or in a stable molecular dispersion. The in vitro release studies confirmed the sustained release for distinct MTX-loaded PLGA microparticles. The involved drug release mechanism was non Fickian diffusion, which was confirmed by Kornmeyer-Peppas kinetic model. The experimental results demonstrated that the MTX-loaded PLGA microparticles were successfully obtained by spray drying and its potential as prolonged drug release system.