Colloidal Behavior of Cellulose Nanocrystals Grafted with Poly(2-alkyl-2-oxazoline)s.

Polymer grafting onto cellulose nanocrystals (CNCs) has been used as a tool to improve CNC dispersion in nonpolar solvents or polymeric matrixes. The grafting of flexible polymer chains onto rigid particle surfaces leads to significant modifications in colloidal behavior. Here, poly(2-alkyl-2-oxazoline)s of well-defined molar mass and narrow molar mass distribution were synthesized by cationic ring-opening polymerization and grafted onto CNC surfaces, where the coupling reaction was favored when partially hydrolyzed polymers were used (reaching 64% reaction yield). The particles grafted with polymer chains could be redispersed in water after freeze-drying, producing stable dispersions, and they were not cell-toxic up to 10 wt % aqueous dispersion. Colloidal stability, nanostructure organization, and rheological behavior of grafted CNC and CNC-grafted CNC mixtures were evaluated. The rheological behavior of grafted nanoparticles, meanwhile, showed new features when compared to original CNC dispersions. Aqueous CNC dispersions showed a liquid crystal nematic organization and rheological behavior characteristic of true gel (at 5 wt %) prior to drying. On the other hand, nanoparticle dispersions behaved as weak gels upon the addition of 10 wt % of CNC-g-(PEtOx95-s-Ei5) under the same conditions. Dispersions of CNC-g-P(PEtOx-s-Ei) particles obtained by redispersion of freeze-dried particles behaved as a fluid, without the presence of the nematic organization. Through oscillatory rheology and time-domain NMR results, it can be concluded that polymer-water interactions are dominant over CNC-water interactions, being responsible for CNC nematic phase disruption. By introducing polymer chains, the introduction of isotropic character modifies water organization, changing the flow behavior of CNC-grafted with poly(oxazoline)s.

Anti-tumor efficacy of hyaluronan-based nanoparticles for the co-delivery of drugs in lung cancer.

Combinations of therapeutic agents could synergistically enhance the response of lung cancer cells. Co-delivery systems capable of transporting chemotherapeutics with different physicochemical properties and with the simultaneous release of drugs remain elusive. Here, we assess the ability of nanoparticles of 30-nm diameter obtained from the self-assembly of hyaluronan-based copolymer targeting CD44 receptors to encapsulate both gefitinib and vorinostat for effective combinational lung cancer treatment. Drug loading was performed by nanoprecipitation. Drug release experiments showed a slow release of both drugs after 5 days. Using two- and three-dimensional lung adenocarcinoma cell cultures, we observed that the nanoparticles were mostly found at the periphery of the CD44-expressing spheroids. These drug-loaded nanoparticles were as cytotoxic as free drugs in the two- and three-dimensional systems and toxicity was due to apoptosis induction. In mouse models, intravenous injection of hyaluronan-based nanoparticles showed a selective delivery to subcutaneous CD44-overexpressing tumors, despite a significant liver capture. In addition, the systemic toxicity of the free drugs was reduced by their co-delivery using the nanoparticles. Finally, intrapulmonary administration of drug-loaded nanoparticles, to avoid a possible hepatic toxicity due to their accumulation in the liver, showed a stronger inhibition of orthotopic lung tumor growth compared to free drugs. In conclusion, hyaluronan-based nanoparticles provide active targeting partially mediated by CD44, less-toxic drug release and improved antitumor efficiency.

Multivalent effect of glycopolypeptide based nanoparticles for galectin binding.

Synthetic glycopolypeptides are versatile glycopolymers used to conceive bioinspired nanoassemblies. In this work, novel amphiphilic glycopolypeptides were designed to incorporate lactose or galactan in order to prepare polymeric nanoassemblies with sizes below 50 nm. The bioactivity of the two different outer surface sugar units was evaluated by defining glycan relative binding affinities to human galectins 1 and 3. A specific multivalent effect was found only for polymeric nanoparticles displaying galactan with a significant increase of the binding activity as compared to free glycan in solution. Such synthetic designs present great potential as therapeutic tools to address galectin related pathologies.

Honey: Chemical composition, stability and authenticity.

The aim of this review is to describe the chemical characteristics of compounds present in honey, their stability when heated or stored for long periods of time and the parameters of identity and quality. Therefore, the chemical characteristics of these compounds were examined, such as sugars, proteins, amino acids, enzymes, organic acids, vitamins, minerals, phenolic and volatile compounds present in honey. The stability of these compounds in relation to the chemical reactions that occur by heating or prolonged storage were also discussed, with increased understanding of the behavior regarding the common processing of honey that may compromise its quality. In addition, the identity and quality standards were described, such as sugars, moisture, acidity, ash and electrical conductivity, color, 5-HMF and diastase activity, along with the minimum and maximum limits established by the Codex Alimentarius.

Xyloglucan-based diblock co-oligomer: synthesis, self-assembly and steric stabilization of proteins.

We propose a novel plant-based amphiphilic diblock co-oligomers (BCO) surfactant containing only carbohydrate segments and examine its potential as a biosourced stabilizer. The synthesis of an amphiphilic xyloglucan-based BCO, composed of a hydrophilic xyloglucan oligosaccharide (XGO) block "clicked" to a hydrophobic peracetylated XGO is described. Dynamic light scattering experiments correlated with transmission electron microscopy observations showed that this new class of amphiphilic BCO self-assembles in water to form spherical micelles with a hydrodynamic diameter of 22 nm. Preliminary studies indicate that the XGO-based BCO sterically stabilizes gliadin and zein nanoparticle suspensions. The stabilization results were compared to those using pluronic F-68, a commercial surfactant. For gliadin nanoparticles, both surfactants result in essentially the same morphology and polydispersity. However, for the zein nanoparticles, the XGO-based BCO stabilizer gave lower polydispersity.

Polimerização das proteínas do leite por transglutaminase: modificação das propriedades funcionais e aplicação em produtos lácteos / Crosslinking of milk proteins by transglutaminas: functional properties modifications and use in dairy products

Este trabalho teve como objetivo destacar as principais características da transglutaminase de origem microbiana (Streptoverticilium mobaraense), seu efeito nas propriedades funcionais e proteínas do leite e sua aplicação em produtos lácteos. São apresentadas as caracaterísticas da enzima e as principais reções que catalisa, destacando-se o comportamento da transglutaminase em diferentes susbstratos (caseína e proteínas do soro) e a alteração nas propriedades funcionais das proteínas láctea após a reação enzimática. A polimerização das proteínas do leite pela transglutaminase parece constituir meio efetivo para o melhoramento das propriedades físicas de produtos lácteos como, queijos, sorvete e iogurte. A reação enzimática catalisada pela transglutaminase confere aos produtos formados características únicas e sua utilização apresenta grande potencial para indústria de alimentos por tratar-se de meio considerado seguro para mofificação protéica.

Copigmentaçäo intra e intermolecular de Antocianinas: uma revisäo / Anthocyanins intra and intermolecular copigmentation: a review

Este trabalho apresenta revisäo de literatura sobre a reaçäo de copigmentaçäo intra e intermolecular e sua relevância na estabilizaçäo de antocianinas. Flavonóides näo-antociânicos, alcalóides, aminoácidos e nucleosídios, entre outros, podem atuar como copigmentos de antocianinas. O aumento na estabilidade das antocianinas ocorre devido à proteçäo fornecida pelo copigmento frente à reaçäo de hidrataçäo do cátion flavilium. Estudos ainda säo necessários para avaliar a estabilidade de antocianinas adicionadas de copigmentos em sistemas modelos de alimentos, visando aumentar o espectro de aplicaçäo dessas como corantes em alimentos e bebidas.