Synthesis of magnetic nanoparticles functionalized with histidine and nickel to immobilize His-tagged enzymes using β-galactosidase as a model.

The aim of this study was to synthesize iron magnetic nanoparticles functionalized with histidine and nickel (FeO-His-Ni) to be used as support materials for oriented immobilization of His-tagged recombinant enzymes of high molecular weight, using β-galactosidase as a model. The texture, morphology, magnetism, thermal stability, pH and temperature reaction conditions, and the kinetic parameters of the biocatalyst obtained were assessed. In addition, the operational stability of the biocatalyst in the lactose hydrolysis of cheese whey and skim milk by batch processes was also assessed.

Immobilization of β-Galactosidases on Magnetic Nanocellulose: Textural, Morphological, Magnetic, and Catalytic Properties.

We describe a process for obtaining nanocrystalline cellulose (NC) by either acidic (H-NC) or alkaline treatment (OH-NC) of microcrystalline cellulose, which was subsequently bonded to magnetic nanoparticles (H-NC-MNP and OH-NC-MNP) and used as support for the immobilization of Aspergillus oryzae (H-NC-MNP-Ao and OH-NC-MNP-Ao) and Kluyveromyces lactis (H-NC-MNP-Kl and OH-NC-MNP-Kl) β-galactosidases. The mean size of magnetic nanocellulose particles was approximately 75 nm. All derivatives reached saturation magnetizations of 7-18 emu/g, with a coercivity of approximately 4 kOe.

Alteplase and DNase for the treatment of pleural empyema in rats.

Background And Objectives: Adjunctive intrapleural fibrinolytic is an option to treat empyema at fibrinopurulent stage, but there is controversy about which should be use. Our objective is to evaluate the action of alteplase and/or desoxyribonuclease at physical and chemical properties in vitro pus derived from an experimental induced empyema in rats.

Methods: Streptococcus pneumoniae was introduced into the pleural cavity by thoracentesis through pleural pressure monitor.

Smart Starch-Poly( N-isopropylacrylamide) Hybrid Microgels: Synthesis, Structure, and Swelling Behavior.

In this study, we present hybrid microgels made of starch nanoparticles (SNPs) and poly( N-isopropylacrylamide) [p(NIPAM)]. SNPs were formed through nanoprecipitation. Hybrid microgels were prepared by surfactant-free precipitation polymerization (SFPP) or in the presence of surfactant precipitation polymerization (PP) at different NIPAM/SNP ratios.

Synthesis and characterization of acetylated amylose and development of inclusion complexes with rifampicin.

Amylose (AM) tends to form single helical inclusion complexes with suitable agents. These complexes are considered promising biomaterial carrier since the guest molecules can be released later, leading to many applications, especially in the pharmaceutical industry. Rifampicin (RIF) has long been recognized as an active drug against Mycobacterium tuberculosis, however, the administration of RIF in high dosages can originate unwanted side-effects.

Self-assembled carbohydrate-based vesicles for lectin targeting.

This study examined the physicochemical interactions between vesicles formed by phosphatidylcholine (PC) and glycosylated polymeric amphiphile N-acetyl-β-d-glucosaminyl-PEG-docosanate (CPEGGlcNAc) conjugated with Bauhinia variegata lectin (BVL). Lectins are proteins or glycoproteins capable of binding glycosylated membrane components. Accordingly, the surface functionalization by such entities is considered a potential strategy for targeted drug delivery.

Electroformation of Giant Unilamellar Vesicles: Investigating Vesicle Fusion versus Bulge Merging.

Partially ordered stacks of phospholipid bilayers on a flat substrate can be obtained by the evaporation of a spread droplet of phospholipid-in-chloroform solution. When exposed to an aqueous buffer, numerous micrometric buds populate the bilayers, grow in size over minutes, and eventually detach, forming the so-called liposomes or vesicles. While observation of vesicle growth from a hydrated lipid film under an optical microscope suggests numerous events of vesicle fusion, there is little experimental evidence for discriminating between merging of connected buds, i.

Films based on neutralized chitosan citrate as innovative composition for cosmetic application.

In this work, citrate and acetate buffers, were investigated as neutralizers to chitosan salts in order to provide biocompatible and stable films. To choose the appropriate film composition for this study, neutralized chitosan citrate and acetate films, with and without the plasticizer glycerol, were prepared and characterized by thickness, moisture content, degree of swelling, total soluble matter in acid medium, simultaneous thermal analysis and differential scanning calorimetry. Chitosan films neutralized in citrate buffer showed greater physical integrity resulted from greater thicknesses, lower moisture absorbance, lower tendency to solubility in the acid medium, and better swelling capacities.

Interaction of jack bean (Canavalia ensiformis) urease and a derived peptide with lipid vesicles.

Ureases are metalloenzymes that catalyze the hydrolysis of urea to ammonia and carbon dioxide. Jack bean (Canavalia ensiformis) produces three isoforms of urease (Canatoxin, JBU and JBURE-II). Canatoxin and JBU display several biological properties independent of their ureolytic activity, such as neurotoxicity, exocytosis-inducing and pro-inflammatory effects, blood platelets activation, insecticidal and antifungal activities.

Silver nanoparticle-ionic silsesquioxane: a new system proposed as an antibacterial agent.

Spherical silver nanoparticles with an average size of ca. 5 nm were synthesized in aqueous medium using a charged silsesquioxane containing a quaternary ammonium group, the bridged 1,4-diazoniabicyclo[2.2.

Dynamic rheological properties of native and cross-linked gliadin proteins.

A comparison of cross-linked and native gliadin suspensions, with respect to the state of protein globular structure was carried out using small-angle X-ray scattering (SAXS), dynamic light scattering (DLS) and rheological analysis. Gliadin suspensions were also analyzed in the presence and absence of glycerol. DLS analysis showed that R(h) increased only with gliadin/EDC/NHS suspensions.

Sustained antioxidant activity of quercetin-loaded lipid-core nanocapsules.

Lipid-core nanocapsules (LNC) are vesicular nanocarriers prepared by solvent displacement. LNC have been previously prepared using medium-chain triglyceride and sorbitan monostearate as liquid and solid lipophilic components dispersed in the core, surrounded by poly(epsilon-caprolactone) (PCL). Our objective was to investigate the antioxidant activity of LNC containing quercetin (QUE), a radical scavenger, prepared with octyl methoxycinnamate and sorbitan monostearate as lipophilic core components and PCL as the polymer wall.

Effects of the composite nanovesicles on the physical properties and cellular adhesion of chitosan films.

Chitosan films were prepared by the casting of a chitosan gel in absence and presence of composite nanovesicles. The microscopy images showed the occurrence of agglomerates on the surface and internal pores when the nanovesicles were added to the films, differently from the smooth surface of the pure chitosan films. Despite the hydrophobic character that composite nanovesicles gave to the chitosan films, as showed by the reduction of the water permeation at prolonged times, there was a reduction on the contact angle values for these samples related to the roughness of the surface.

Chitosan coated liposomes as an innovative nanocarrier for drugs.

Chitosomes are chitosan coated liposomes that represent an alternative to conventional liposomes since they present better stability and bioadhesivity. The aim of this work was to develop and evaluate the physico-chemical stability of melatonin (MEL)-loaded chitosomes as well as to compare their properties with that of MEL loaded liposomes. Structural characteristics of nanovesicles were also studied by dynamic light scattering and small angle X-ray scattering.

Echinococcus granulosus antigen B structure: subunit composition and oligomeric states.

Background: Antigen B (AgB) is the major protein secreted by the Echinococcus granulosus metacestode and is involved in key host-parasite interactions during infection. The full comprehension of AgB functions depends on the elucidation of several structural aspects that remain unknown, such as its subunit composition and oligomeric states.

Methodology/principal Findings: The subunit composition of E.

A novel globular protein electrospun fiber mat with the addition of polysilsesquioxane.

The aim of this work has been to elaborate well defined gliadin nanofibers with incorporation of inorganic molecules, such as polyhedral oligomeric silsesquioxane (POSS). Nanofibers were obtained by electrospinning processing, controlling the relevant parameters such as tip-to-collector distance, voltage and feed rate. The fiber mats were characterized by SEM, confocal images, DSC, viscosity, FTIR and conductivimetry analysis.

Wormlike micellar aggregates of saponins from Ilex paraguariensis A. St. Hil. (mate): a characterisation by cryo-TEM, rheology, light scattering and small-angle neutron scattering.

This work reports the physico-chemical characterisation of the micellar structures formed by a saponin fraction obtained from an important South American species, Ilex paraguariensis (mate). The mate saponin-enriched fraction (MSF) mainly comprises triterpenic glycosides and was obtained from mate green fruits through solid-phase extraction. The physico-chemical studies focused on the determination of the critical micellar concentration (CMC), the size and shape of the micelles, using conventional transmission electronic microscopy (TEM), as well as Cryo-TEM, light scattering and small-angle neutron scattering.

Structure of self-organized diblock copolymer solutions in partially miscible solvents.

A diblock copolymer dissolved in a mixture of partially miscible solvents creates a self-organized microemulsion with a morphology that depends on the numerous parameters of the system. We discuss one particular case of spherical particles (containing the minority solvent) forming a hard gel with cubic structure and demonstrate using high-resolution synchrotron scattering experiments that the self-organized solution has a BCC structure. After fitting one- and two-dimensional form factors we extract from the data the one- and two-dimensional structure factors, S(q) and S(q,phi).

Effect of nanovesicle-encapsulated nisin on growth of Listeria monocytogenes in milk.

Commercial nisin was encapsulated in nanovesicles (mean diameter 140 nm) prepared from partially purified soy lecithin. Nisin-loaded liposomes and unencapsulated (free) nisin were initially tested in BHI medium and skim milk inoculated with Listeria monocytogenes and incubated for 48 h at 30 degrees C. At such abuse temperature conditions, free nisin showed better inhibitory than the liposomal counterparts.

Interaction between phospholipids bilayer and chitosan in liposomes investigated by 31P NMR spectroscopy.

The interaction between chitosan and the polar head of phosphatidylcholine (PC) is discussed for a composite nanovesicle obtained by incorporating chitosan in the organic phase before PC self-assembling. Nanovesicles free of chitosan are studied in parallel to allow the comparison concerning modifications produced on the composite system. Zeta Potential increases in the presence of chitosan and with the increase in its concentration proving the localization of the polymer over the external surface of the vesicle as one interaction site.

Internal structural characterization of triblock copolymer micelles with looped corona chains.

We report the characterization through SAXS measurements of micelles produced from a new series of block copolymers: one diblock and four triblock copolymers bearing short poly[5-(N,N-diethylamino)isoprene] and long polystyrene blocks. Micellar aggregates produced in DMF (selective solvent for polystyrene) from the same set of samples were previously successfully characterized through light scattering measurements. The X-ray scattering profiles of starlike (from the diblock copolymer sample) and flowerlike micelles (from the triblock copolymers samples) could be fitted using the spherical copolymer micelle model proposed by Pedersen and Gerstenberg (Macromolecules 1996, 29, 1363.

Electroformation of giant vesicles from an inverse phase precursor.

We discuss a simple modification of the well-known method of giant vesicle electroformation that allows for a direct addition of water-soluble species to the phospholipid bilayers. Using this modified method, we prepare phospholipid vesicles decorated with chitosan, a water-soluble polysaccharide currently investigated for potential pharmacological applications. We find that the method allows this polysaccharide with primary amino groups on every glucose subunit to be tightly bound to the membrane, rather than simply being encapsulated.

Aggregation behavior of a new series of ABA triblock copolymers bearing short outer A blocks in B-selective solvent: from free chains to bridged micelles.

A combination of dynamic (DLS) and static (SLS) light scattering measurements was employed to study the self-assembly behavior of a new series of triblock copolymers bearing poly[5-(N,N-diethylamino isoprene)] (PAI) short outer blocks and polystyrene (PS) as the major middle block. Previously, it was verified that PAI outer blocks can be quaternized leading the formation of crew-cut aggregates in water (Riegel, I. C.

Effect of the alkaline treatment on the ultrastructure of C-type starch granules.

The effect of alkaline treatment on the ultrastructure of C-type starch granules was investigated during the alkaline extraction of Araucaria angustifolia (pinhao) starch. The efficiency in protein removal was evaluated using intrinsic fluorescence and Kjeldahl's method. In parallel, morphological changes of starch granules were observed using scanning electron microscopy and atomic force microscopy.

Determining the simultaneous presence of drug nanocrystals in drug-loaded polymeric nanocapsule aqueous suspensions: a relation between light scattering and drug content.

The encapsulation of lipophilic drugs in polymeric nanoparticles can form simultaneously both polymeric nanoparticles and drug nanocrystals. The objective was to detect the presence of nanocrystals in the nanoparticle suspensions using a simple methodology, and to determine if the nanocrystals are formed during preparation or by drug leakage from the particles during storage. Indomethacin was chosen as drug model.