Physicochemical characterization of nanoparticles formed between DNA and phosphorylcholine substituted chitosans

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

Multifunctional antitumor magnetite/chitosan-l-glutamic acid (core/shell) nanocomposites

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

Poly(epsilon-caprolactone) nanocapsules carrying the herbicide atrazine: effect of chitosan-coating agent on physico-chemical stability and herbicide release profile

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

Desenvolvimento de nanopartículas de quitosana para adminstração nasal de zidovudina

Zidovudine (AZT) is the drug most commonly used in AIDS treatment, isolated or in combination with other antiretroviral agents, but it has certain limitations due to its therapeutic dose-dependent haematological toxicity. In addition, it has low oral bioavailability, since it undergoes pre-systemic metabolism. The nasal route has been used as an alternative route for drug administration, because it can promote its direct absorption to blood circulation, avoiding hepatic metabolism. However, this route presents as a factor limiting the mucociliary clearance mechanisms that remove quickly the formulation of the nasal cavity. To prolong the residence time of formulations, in this direction, has been proposed the development of mucoadhesive systems. Among the various existing systems, the use of chitosan (QS), as mucoadhesive polymer, has been widely exploited in the preparation of nanoparticles (NPs). The objective of this study was to develop and characterize QS’s NPs for intranasal administration of AZT. For both NPs have been developed by ionic crosslinking of QS with sodium tripolyphosphate (TPP). These NPs were characterized by studies of particle size distribution, zeta potential, morphology, mucoadhesion tests, assessing the ability of encapsulation of the drug and permeation profile of AZT. The evaluation of AZT in the NPs was determined by UV-Vis spectroscopy. Mucoadhesion measures were made using a texture analyzer, using a mucin disk and porcine mucous membrane , and permeation assay were conducted using porcine nasal mucous membrane adapted to the Franz cell. These results suggest that the systems in hand have great potential for nasal AZT administration

Immobilization of papain on chitin and chitosan and recycling of soluble enzyme for deflocculation of saccharomyces cerevisiae from bioethanol distilleries

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

Effect of mucoadhesive polymers on the in vitro performance of insulin-loaded silica nanoparticles: Interactions with mucin and biomembrane models

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

Surface engineering of silica nanoparticles for oral insulin delivery: characterization and cell toxicity studies

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

Hemocompatibility of poly(epsilon-caprolactone) lipid-core nanocapsules stabilized with polysorbate 80-lecithin and uncoated or coated with chitosan

The hemocompatibility of nanoparticles is of critical importance for their systemic administration as drug delivery systems. Formulations of lipid-core nanocapsules, stabilized with polysorbate 80-lecithin and uncoated or coated with chitosan (LNC and LNC-CS), were prepared and characterized by laser diffraction (D[4,3]: 129 and 134 nm), dynamic light scattering (119 nm and 133 nm), nanoparticle tracking (D50: 124 and 139 nm) and particle mobility (zeta potential: -15.1 mV and + 9.3 mV) analysis. In vitro hemocompatibility studies were carried out with mixtures of nanocapsule suspensions in human blood at 2% and 10% (v/v). The prothrombin time showed no significant change independently of the nanocapsule surface potential or its concentration in plasma. Regarding the activated partial thromboplastin time, both suspensions at 2% (v/v) in plasma did not influence the clotting time. Even though suspensions at 10% (v/v) in plasma decreased the clotting times (p < 0.05), the values were within the normal range. The ability of plasma to activate the coagulation system was maintained after the addition of the formulations. Suspensions at 2% (v/v) in blood showed no significant hemolysis or platelet aggregation. In conclusion, the lipid-core nanocapsules uncoated or coated with chitosan are hemocompatible representing a potential innovative nanotechnological formulation for intravenous administration. (C) 2012 Elsevier B. V. All rights reserved.

Antioxidant Effects of Quercetin and Catechin Encapsulated into PLGA Nanoparticles

Polymeric nanoparticles (PLGA) have been developed for the encapsulation and controlled release of quercetin and catechin. Nanoparticles were fabricated using a solvent displacementmethod. Physicochemical properties were measured by light scattering, scanning electron microscopy and zeta-potential, X-ray diffraction, infrared spectroscopy and differential scanning calorimetry. Encapsulation efficiency and in vitro release profiles were obtained from differential pulse voltammetry experiments. Antioxidant properties of free and encapsulated flavonoids were determined by TBARS, fluorescence spectroscopy and standard chelating activity methods. Relatively small (d approximate to 400 nm) polymeric nanoparticles were obtained containing quercetin or catechin in a non-crystalline form (EE approximate to 79%) and the main interactions between the polymer and each flavonoid were found to consist of hydrogen bonds. In vitro release profiles were pH-dependant, the more acidic pH, the faster release of each flavonoid from the polymeric nanoparticles. The inhibition of the action of free radicals and chelating properties, were also enhanced when quercetin and catechin were encapsulated within PLGA nanoparticles. The information obtained from this study will facilitate the design and fabrication of polymeric nanoparticles as possible oral delivery systems for encapsulation, protection and controlled release of flavonoids aimed to prevent oxidative stress in human body or food products.

Polymeric Nanoparticles as Oral Delivery Systems for Encapsulation and Release of Polyphenolic Compounds: Impact on Quercetin Antioxidant Activity & Bioaccessibility

A delivery system containing polymeric (Eudragit) nanoparticles has been developed for encapsulation and controlled release of bioactive flavonoids (quercetin). Nanoparticles were fabricated using a solvent displacement method. Particle size, morphology, and charge were measured by light scattering, electron microscopy and zeta-potential. Encapsulation efficiency (EE) and release profiles were determined using electrochemical methods. Molecular interactions within the particle matrix were characterized by X-ray diffraction, differential scanning calorimetry, and infrared spectroscopy. Antioxidant properties of free and encapsulated quercetin were analyzed by TBARS and fluorescence spectroscopy. Bioaccessibility of quercetin was evaluated using an in vitro digestion model. Relatively small (d a parts per thousand aEuro parts per thousand 370 nm) anionic polymeric nanoparticles were formed containing quercetin in a non-crystalline form (EE a parts per thousand aEuro parts per thousand 67 %). The main interaction between quercetin and Eudragit was hydrogen bonding. Encapsulated quercetin remained stable during 6 months storage and maintained its antioxidant activity. Quercetin bioaccessibility within simulated small intestinal conditions was improved by encapsulation. The knowledge obtained from this study will facilitate the rational design and fabrication of polymeric nanoparticles as oral delivery systems for encapsulation, protection, and release of bioactive compounds.

In vitro drug permeation from chitosan pellets

The purpose of this study was to prepare and characterize coated pellets for controlled drug delivery. The influence of chitosan (CS) in pellets was evaluated by swelling, in vitro drug release and intestinal permeation assays. Pellets were coated with an enteric polymer, Kollicoat (R) MAE 30 DP, in a fluidized-bed apparatus and the coating formulations were based on a factorial design. Metronidazole (MT) released from coated and uncoated pellets were assessed by dissolution method using Apparatus I. Intestinal permeation was evaluated by everted intestinal sac model in rats, used to study the absorption of MT from coated pellets containing CS or not through the intestinal tissue. Although the film coating avoided drug dissolution in gastric medium, the overall drug release and intestinal permeation were dependent on the presence of CS. Thus, pellets containing CS show potential as a system for controlled drug delivery. (C) 2011 Elsevier Ltd. All rights reserved.

ALTERNATING CURRENT DIELECTROPHORESIS OF CORE-SHELL NANOPARTICLES: EXPERIMENTS AND COMPARISON WITH THEORY

Nanoparticles are fascinating where physical and optical properties are related to size. Highly controllable synthesis methods and nanoparticle assembly are essential [6] for highly innovative technological applications. Among nanoparticles, nonhomogeneous core-shell nanoparticles (CSnp) have new properties that arise when varying the relative dimensions of the core and the shell. This CSnp structure enables various optical resonances, and engineered energy barriers, in addition to the high charge to surface ratio. Assembly of homogeneous nanoparticles into functional structures has become ubiquitous in biosensors (i.e. optical labeling) [7, 8], nanocoatings [9-13], and electrical circuits [14, 15]. Limited nonhomogenous nanoparticle assembly has only been explored. Many conventional nanoparticle assembly methods exist, but this work explores dielectrophoresis (DEP) as a new method. DEP is particle polarization via non-uniform electric fields while suspended in conductive fluids. Most prior DEP efforts involve microscale particles. Prior work on core-shell nanoparticle assemblies and separately, nanoparticle characterizations with dielectrophoresis and electrorotation [2-5], did not systematically explore particle size, dielectric properties (permittivity and electrical conductivity), shell thickness, particle concentration, medium conductivity, and frequency. This work is the first, to the best of our knowledge, to systematically examine these dielectrophoretic properties for core-shell nanoparticles. Further, we conduct a parametric fitting to traditional core-shell models. These biocompatible core-shell nanoparticles were studied to fill a knowledge gap in the DEP field. Experimental results (chapter 5) first examine medium conductivity, size and shell material dependencies of dielectrophoretic behaviors of spherical CSnp into 2D and 3D particle-assemblies. Chitosan (amino sugar) and poly-L-lysine (amino acid, PLL) CSnp shell materials were custom synthesized around a hollow (gas) core by utilizing a phospholipid micelle around a volatile fluid templating for the shell material; this approach proves to be novel and distinct from conventional core-shell models wherein a conductive core is coated with an insulative shell. Experiments were conducted within a 100 nl chamber housing 100 um wide Ti/Au quadrapole electrodes spaced 25 um apart. Frequencies from 100kHz to 80MHz at fixed local field of 5Vpp were tested with 10-5 and 10-3 S/m medium conductivities for 25 seconds. Dielectrophoretic responses of ~220 and 340(or ~400) nm chitosan or PLL CSnp were compiled as a function of medium conductivity, size and shell material.

Resposta imune do antígeno de superfície de hepatite B administrado via nasal em nanopartículas de quitosana liofilizadas

A nanotecnologia tornou possível estruturar nanopartículas (NPs), utilizando-se polímeros biodegradáveis e atóxicos, como a quitosana (QS) - capaz de carrear e disponibilizar antígenos para a mucosa, devido sua propriedade mucoadesiva. Uma vacina liofilizada, em comparação a uma formulação líquida, possui inúmeras vantagens, tais como melhora na estabilidade do produto e melhor resistência às variações de temperatura, aumentando sua vida de prateleira e possibilitando melhor logística do produto aos locais onde o acesso à rede refrigerada é difícil; ademais, um produto liofilizado tem sua mucoadesividade aumentada, possibilitando maior tempo de permanência na mucosa. O presente trabalho teve como objetivo observar a resposta imune, em camundongos, de uma vacina desenvolvida por um mecanismo de entrega intranasal do HBsAg (Antígeno de superfície da Hepatite B) encapsulado pelo método de incorporação em nanopartículas de quitosana (NPs) liofilizadas. A formação das NPs foi realizada pela interação eletroestática da quitosana e do TPP (tripolifosfato de sódio), utilizando método de geleificação iônica. Formulações de NPs com glicina 5% apresentaram boas características após reconstituição, umidade residual inferior a 1% e processo de liofilização de 13 horas. Foi avaliada a imunogenicidade da inoculação do HBsAg em formulações de NPs de quitosana líquida e liofilizada, verificando-se que a forma líquida produziu anticorpos IgG contra HBsAg.

Application of chitosan loaded with metal oxide nano particles to remove lead present from sea water

Chitosan is a natural polymer obtained by deacetylation of chitin. After cellulose chitin is the second most abundant polysaccharide in nature. It is biologically safe, non-toxic, biocompatible and biodegradable polysaccharide. Chitosan loaded with zinc oxide nanoparticles have gained more attention bio sorbent because of their better stability, low toxicity, simple and mild preparation method and high sorption capacity. Chitosan loaded with zinc oxide nanoparticles have been prepared of chitosan. The physicochemical properties of nanoparticles were characterized by Fourier Transform Infrared (FTIR), Scanning Electron Microscope (SEM) Analysis. Its sorption capacity for lead and cadmium ions studied. Factors such as initial concentration of lead ions, cadmium ions sorbent amount, contact time, pH and temperature were investigated. It is found that chitosan loaded with zinc oxide nanoparticles could sorb lead and cadmium ions effectively, this sorption rate was affected significantly by initial concentration of lead and cadmium ions, sorbent amount, contact time, pH of solution. The maximum of percentage of lead sorption was 98 % with initial concentration 3 mg/l and sorbent amount 0.05 g, pH 11 in 45 min and cadmiumwas90 %with initial concentration 3mg/l and sorbent amount 0.05 g, pH 11 in45 min. Consequently chitosan loaded with zinc oxide nanoparticles demonstrated greater fixation ability for lead ions than cadmium ions.

Polymeric alginate nanoparticles containing the local anesthetic bupivacaine

Bupivacaine (BVC; S75-R25, NovaBupinanoparticles were 87 +/- 1.5 and 76 +/- 0.9%, respectively. The average diameters and zeta potentials of the nanoparticles were measured for 30 days, and the results demonstrated the good stability of these particles in solution. The in vitro release kinetics showed a different behavior for the release profile of BVC in solution, compared with BVC-loaded alginate nanoparticles. In vitro and in vivo assays showed that alginate-chitosan BVC (BVC(ALG-CHIT)) and alginate-AOT BVC (BVC(ALG-AOT)) presented low cytotoxicity in 3T3-fibroblasts, enhanced the intensity, and prolonged the duration of motor and sensory blockades in a sciatic nerve blockade model.