Nanokapsuły typu rdzeń-otoczka na bazie chitozanu

N-dodecyl derivative of cationically modified chitosan was used to prepare core-shell nanocapsules templated on liquid cores. Surfactant-free method based on ultrasound-assisted direct emulsification of aqueous solution of polysaccharide with oleic acid was applied. Formation of spherical capsules was confirmed by scanning and transmission electron microscopies. Dynamic light scattering measurements were used to determine physicochemical parameters of the obtained particles as well as to follow the process of multilayer shell formation. Confocal microscopy was applied to examine the ability of encapsulation of hydrophobic compounds inside the cores of the nanocapsules. Performed studies confirmed that hydrophobically modified cationic chitosan provides long-term stabilization of oil-in-water emulsion for biomedical applications as no toxic effect was observed in acute oral toxicity studies.Do przygotowania nanokapsuł na ciekłych rdzeniach stabilizowanych bez użycia małocząsteczkowych surfaktantów użyto N-dodecylowej pochodnej zmodyfikowanego kationowo chitozanu. Kapsuły otrzymano w procesie wspomaganej ultradźwiękami bezpośredniej emulsyfikacji fazy wodnej zawierającej modyfikowany polisacharyd oraz kwas oleinowy. Powstawanie sferycznych kapsuł potwierdzono za pomocą skaningowej oraz transmisyjnej mikroskopii elektronowej. Obrazowanie z użyciem mikroskopii konfokalnej posłużyło natomiast do zbadania zdolności do enkapsulacji hydrofobowych barwników w rdzeniach chitozanowych nanokapsuł. Stosując technikę dynamicznego rozpraszania światła wyznaczono fizykochemiczne parametry nanoemulsji oraz stwierdzono powstawanie wielowarstwowych otoczek. Przeprowadzone badania dowiodły, że zastosowanie hydrofobowo zmodyfikowanej kationowej pochodnej chitozanu pozwala na uzyskanie stabilnych w czasie emulsji typu olej w wodzie. Wykazany brak toksyczności układów w warunkach in vivo pozwala na ich zastosowanie do celów biomedycznych

Hydrophobically coated superparamagnetic iron oxides nanoparticles incorporated into polymer-based nanocapsules dispersed in water

This paper reports the characterization of iron oxide magnetic nanoparticles obtained via the thermal decomposition of an organometallic precursor, which were then loaded into nanocapsules prepared via the emulsification process in the presence of an amphiphilic derivative of chitosan. The applied synthetic method led to the formation of a hydrophobic layer on the surface of nanoparticles that enabled their loading in the hydrophobic liquid inside of the polymer-based capsules. The average diameter of nanoparticles was determined to be equal to 15 nm, and they were thoroughly characterized using X-ray diffraction (XRD), magnetometry, and Mössbauer spectroscopy. A core–shell structure consisting of a wüstite core and maghemite-like shell was revealed, resulting in an exchange bias effect and a considerable magnetocrystalline anisotropy at low temperatures and a superparamagnetic behavior at room temperature. Importantly, superparamagnetic behavior was observed for the aqueous dispersion of the nanocapsules loaded with the superparamagnetic nanoparticles, and the dispersion was shown to be very stable (at least 48 weeks). The results were analyzed and discussed with respect to the potential future applications of these nanoparticles and nanocapsules based on biopolymers as platforms designed for the magnetically navigated transport of encapsulated hydrophobic substances

Polymeric Capsules as Chemical Phototoreactors

Niniejsza praca dotyczy zastosowania fotoaktywnego amfifilowego kopolimeru szczepionego chlorowodorku polialliloaminy szczepionego poliwinylonaftalenem (PAH-graft-PVN) do stabilizacji nanokapsuł o ciekłych rdzeniach.Badany polielektrolit wykazuje tendencję do samoorganizacji w roztworach wodnych. Celem ograniczenia kontaktu z polarnym medium hydrofobowych ramion tworzy „kieszenie hydrofobowe”, w których możliwa jest solubilizacja hydrofobowych związków. Na granicy faz woda-olej jego konformacja ulega rozluźnieniu umożliwiając opłaszczenie kropli oleju oraz jej stabilizację poprzez zakotwiczenie w niej hydrofobowych ramion. Otrzymuje się w ten sposób stabilne nanokapsuły, bez konieczności dodawania surfaktantów.Sprawdzono wpływ pH roztworu, siły jonowej i temperatury na konformację badanego kopolimeru, a także jego zdolność do solubilizacji związków hydrofobowych oraz możliwość zachodzenia transferu energii pomiędzy chromoforami naftalenowymi a solubilizowaną sondą. Badania objęły także określenie możliwości stabilizacji kapsuł na ciekłych rdzeniach, a także zdolności do enkapsulacji związków hydrofobowych, transferu energii jak i możliwości zachodzenia wewnątrz kapsuł reakcji fotoutleniania zamkniętej w nich sondy hydrofobowej.W trakcie badań dokonano charakterystyki kopolimeru i kapsuł z użyciem metody dynamicznego rozpraszania światła (DLS), metod spektroskopowych i skaningowej mikroskopii elektronowej (SEM) W toku badań wykazano zdolność kopolimeru do samoorganizacji oraz do tworzenia stabilnych kapsuł spełniających rolę fotoreaktorów.This paper concers the use of photoactive amphiphilic copolymer of poly(vinylnaphthalene) grafted onto poly(allylamine hydrochloride) (PAH-graft-PVN) to stabilize nanonapsules with liquid cores.In aqueous solution polymeric chains self-assemble to minimize the contact of hydrophobic side chains with polar medium. Hydrophobic domains that are created may be used to solubilize poorly soluble organic compounds. At the water-oil interface polymeric chains uncoil and hydrophobic arms anchored in oil enable stabilization of the so-formed capsule on liquid cores without low molecular weight surfactants.In this study, the characterization of the polymer was made using the dynamic light scattering technique (DLS), spectrofluorometry as well as scanning electron microspopy (SEM). The influence of pH, ionic strength, temperature on the polymer conformation, solubilization of fluorescent probe in hydrophobic domains and possibility of energy transfer was investigated.The possibility of stabilization of capsules as well as ability to encapsulate hydrophobic compounds, energy transfer and photooxidation of encapsulated compound was investigated. The characterization of prepared capsules was also made via DLS and spectrofluorymetry methods. The ability of self - assembly of the copolymer as well as the ability of stabilization of capsules made in surfactant-free process were confirmed. Moreover, potential usage as fotoreactor was also proven

The Self-Assembly Phenomenon of Poloxamers and Its Effect on the Dissolution of a Poorly Soluble Drug from Solid Dispersions Obtained by Solvent Methods

The self-assembly phenomenon of amphiphiles has attracted particular attention in recent years due to its wide range of applications. The formation of nanoassemblies able to solubilize sparingly water-soluble drugs was found to be a strategy to solve the problem of poor solubility of active pharmaceutical ingredients. Binary and ternary solid dispersions containing Biopharmaceutics Classification System (BCS) class II drug bicalutamide and either Poloxamer®188 or Poloxamer®407 as the surface active agents were obtained by either spray drying or solvent evaporation under reduced pressure. Both processes led to morphological changes and a reduction of particle size, as confirmed by scanning electron microscopy and laser diffraction measurements. The increase in powder wettability was confirmed by means of contact angle measurements. The effect of an alteration of the crystal structure was followed by powder X-ray diffractometry while thermal properties were determined using differential scanning calorimetry. Interestingly, bicalutamide exhibited a polymorph transition after spray drying with the poloxamer and polyvinylpyrrolidone (PVP), while the poloxamer underwent partial amorphization. Moreover, due to the surface activity of the carrier, the solid dispersions formed nanoaggregates in water, as confirmed using dynamic light scattering measurements. The aggregates measuring 200–300 nm in diameter were able to solubilize bicalutamide inside the hydrophobic inner parts. The self-assembly of binary systems was found to improve the amount of dissolved bicalutamide by 4- to 8-fold in comparison to untreated drug. The improvement in drug dissolution was correlated with the solubilization of poorly soluble molecules by macromolecules, as assessed using emission spectroscopy