Academic literature on the topic 'Nanoencapsulation'

Catalytic nanoreactors, prepared by the Layer-by-Layer encapsulation of zeolite H-Beta, were used in the dynamic kinetic resolution (DKR) of 1-phenylethanol and 1-indanol. Yields for both alcohols were clearly above 50%, with ee’s over 85%, indicating successful protection of the pH-sensitive enzyme, candida antarctica lipase B, from the acidic zeolite. Attention proceeded to the DKR of amines, which can involve the undesired hydrogenolysis reaction during the racemisation step. Thus, the phenomenon of hydrogenolysis was investigated. The hydrogenolysis of various amines, imines, and nitriles with an aromatic ring adjacent to the a-carbon was achieved under relatively mild conditions over Pd/C in high yield. The relationship between the various reactions involved in hydrogenolysis and thus hydrogenation of nitriles was clarified, which lead to the proposal of a mechanism based on homogeneous analogues. The mechanism provided an explanation for the ease of hydrogenolysis of substrates with an aromatic ring adjacent to the (it-carbon: the carbometallated intermediate is more stable when the aromatic ring is in that position. DFT calculations not only supported this explanation, but also indicated that the affinity of the aromatic ring to the Pd/C surface is also responsible for the ease of hydrogenolysis. A kinetic model was then proposed to explain why the relatively mild conditions enabled continual hydrogenolysis to occur. The high catalyst loadings, combined with a limited rate of H2 dissolution into the solvent, were responsible, as the hydrogenation reaction (unlike the hydrogenolysis) remained diffusion limited. Furthermore, at very low catalyst loadings, benzylamine was found to poison the catalyst and prevent continued hydrogenolysis. The knowledge gained on hydrogenolysis was then applied to the hydrogenolysis of secondary amines. It was found that the larger the difference between the relative rates of hydrogenolysis of the secondary amine’s constituent primary amines, the more selective the cleavage of the faster C-N bond in the secondary amine. Furthermore, the hydrogenolysis of a secondary amine is faster than either of its constituent primary amines, while steric hindrance when the amine is substituted at the (it-carbon similarly decreases the rate of hydrogenolysis. Both factors are consistent with the necessary formation of a Schiff base for the hydrogenolysis of a primary amine. However, an important exception was found. When one of the constituent primary amines prevents favourable access to the catalyst surface, the secondary amine is unable to undergo hydrogenolysis.

2010 - 2011<br>The increase in dietary-intake-related illnesses, such as obesity, cardiovascular diseases, hypertension, diabetes and cancer, have made in recent years the development of health-and-wellness promoting foods a priority of the food industry. Clinical studies have demonstrated tangible health benefits that may be derived from the intake of bioactive compounds. However many difficulties are associated with their inclusion in food matrices, due to a very low solubility in water and easy degradation by hostile environmental conditions once extracted from plant tissues. Furthermore, poor solubility also means lower absorption in the gastrointestinal tract and, therefore, limited bioavailability. In the food industry, it has become apparent that there is a pressing need for edible delivery system to efficiently encapsulate, protect and release bioactive compounds when developing functional foods. This thesis was addressed to the study and engineering of nanoencapsulation systems, above all nanoemulsions and solid lipid nanoparticles, with superior capabilities of a) protecting the encapsulated bioactive compounds from interaction with food ingredients, keeping their functional properties and preventing the deterioration of the food itself (i.e. oxidation of fat), b) reducing the impact on the organoleptic properties of food and c) improving the absorption and bioavailability of the bioactives, due to the subcellular size of the nanocapsules, which may potentially enhance passive transport mechanisms (i.e. related to the concentration gradient) across the intestinal wall. The research activity has contributed to the advance of the knowledge in the field of the science of colloids, through the specific investigation of the effects of formulation and process parameters, which influence nanoemulsion production, as well as to a deeper comprehension of the technological and biological aspects of the incorporation of the nanoencapsulated compounds in food matrices and explication of their activity. Three different classes of bioactive compounds were chosen as model systems of the experimental work, namely curcumin, resveratrol and essential oils. Both curcumin and resveratrol are antioxidant compounds with markedly low solubility both in aqueous and lipid phase, hence requiring the development of specific formulations. In contrast, essential oils can be easily blended with oils, but require their diffusion through the aqueous phase to attack the cell membrane of microorganisms and act as antimicrobials. Therefore, novel formulations were developed using a combination of hydrophilic (sugar ester, defatted soy lecithin, polysorbate 20) and lipophilic emulsifiers (soy lecithin, glycerol monooleate) to encapsulate resveratrol in peanut oil droplets and disperse it in aqueous systems at a concentration of 100 mg/L, ten times higher than the therapeutic blood concentration. In the same way, curcumin has been encapsulated in solid lipid particles, using stearic acid as lipid phase, at a maximum concentration 1600 times higher than the solubility of curcumin in water (0.6 mg/L). Once the formulation was defined, the issue of the actual fabrication of the nanometric delivery systems was faced from a fundamental point of view. In particular, the production of food nanoemulsions by high pressure homogenization (HPH) has been investigated, focusing on the effect on droplet nanonization of emulsifier type and concentration, as well as of the geometry of the homogenization chamber. The reported results showed that the kinetic parameters of the emulsification process can be primarily correlated with the interfacial and dynamic properties of the emulsifiers, while the fluid-dynamics regime established in the homogenization chamber contributes only to a lesser extent. Nevertheless, the correct design of the homogenization chamber may help in obtaining uniform fluid-dynamic conditions, which ensure a narrow droplet size distribution. The issues related to the physicochemical stability of nanoencapsulated bioactive compounds was faced for resveratrol and curcumin, trying to improve the formulation based on the inputs derived from accelerated ageing studies, that could simulate the food processing and the shelf life of the final product. The results obtained demonstrated that the nanoemulsions based on soy lecithin/sugar esters and Tween 20/glycerol monooleate can better encapsulate resveratrol in the lipid matrix, protecting it both during accelerated ageing and gastro-intestinal digestion and promoting a sustained release. Moreover, these formulations, having smaller mean droplet diameters (below 200 nm), remained physically stable also after the digestion process, allowing the resveratrol to reach the intestinal wall entrapped in the lipid droplets. The subcellular dimension and the compatibility with cell membranes of the developed formulations also resulted in a higher permeability through the intestinal wall, which was simulated studying the transport through Caco-2 cell monolayers grown on permeable supports. Generally, the apparent permeability of most compounds falls in a range of 1×10-7 cm/sec (poorly transported compound) to 1×10-5 cm/sec (well-transported compound). The apparent permeability of resveratrol encapsulated in different nanoemulsion-based delivery systems resulted always in the range indicated, demonstrating that nanoencapsulation can improve passive transport mechanisms. In particular, soy lecithin/sugar esters-based formulation showed an higher permeability due to the presence of soy lecithin, which, having a structure similar to the phospholipid bilayers of the cellular membrane, favours the absorption and the entrapment of the oil droplets in the microvilli and their consequent transport through the cell membrane. Another remarkable result of the present thesis is that for the first time the effect of the delivery systems on the antioxidant activity of nanoencapsulated compounds was investigated, using a biological-based approach that integrated the classical chemical approaches. More specifically, an improved cellular assay was developed, that enabled to measure exclusively the residual activity of nanoencapsulated bioactive that penetrated inside Caco-2 cells, giving precious information on the combination of the mass transfer promotion and protection by the delivery systems. Finally, the technological issue related to the incorporation into fruit juices of essential oils encapsulated into nanometric delivery systems was investigated, having as goal the design of systems that are able to enhance antimicrobial activity of the bioactive compounds, while minimizing the impact on the quality attributes of the final product. The results showed that, due to the higher antimicrobial activity of the nanoencapsulated essential oils, lower antimicrobial concentrations are required for a bactericidal action with a minimal alteration of the organoleptic properties of the juice. [edited by author]<br>X n.s.

Bacteria biohazards, such as Anthrax, are responsible for causing mild to serious illnesses in humans and animals. The primary aim of this research study was to develop a rapid one step assay to detect and neutralize bacteria-based biohazards, using an Immunoliposome-nanoparticle complex. An Anthrax model, Bacillus cereus, was grown for 3 hours and diluted 1:25 in media (2.0 x 107 cfu/ml). The Bacillus cereus was interacted with an Immunoliposome-nanoparticle complex containing an MgO-C 2 neutralization agent. The samples were analyzed via flow cytometry with a 1:8:1 ratio Bacillus cereus, Immunoliposome-nanoparticle complex, and Ethidium homodimer-1 for two hours. The results obtained showed when the Immunoliposome-nanoparticle complex were interacted with bacteria both detection and neutralization occurred immediately. As incubation time increased, fluorescence shifted closer to the control region. Therefore, bacteria can be immediately detected with the Immunoliposomenanoparticles complex, and high levels of neutralization can be achieved less than two hours of incubation.

Glycation of whey proteins results in food-grade composites with modified physicochemical properties. Here, the reaction between glucose and bovine serum albumin (BSA) is promoted under wet-heating conditions. The glycated protein is characterized in depth and compared to the native counterpart and the impact of glycation on properties like net surface charge, particle size and surface hydrophobicity are observed. Conjugation with glucose reduced the surface hydrophobicity of BSA but the interactions between albumin and curcumin became stronger, which contradicts the direct relationship between curcumin binding affinity and protein surface hydrophobicity described in the literature. Nonetheless, curcumin was still capable of quenching the intrinsic fluorescence of the protein after conjugation with glucose and leads to the conclusion that curcumin and BSA interact in a different manner upon glycation. This thesis also depicts mucin as a forthcoming model in the study of nanoparticle interactions with intestinal mucus and glycation posed no effect on such interactions.

Micro- and nanoencapsulation have generated great interest over the last years in multiple fields. Particularly in the food industry, this technology presents potential applications for the development of smart packaging structures, as well as for the protection of sensitive ingredients and the production of novel healthy foods. Therefore, in this thesis, the development of different encapsulation structures of interest in the food area was carried out. Specifically, capsules were obtained through electrohydrodynamic processing, since this technology presents several advantages over other well-established encapsulation technologies. For instance, it does not require the use of high temperatures and encapsulation structures from some biopolymers can be attained by using aqueous solutions. Initially, microencapsulation for smart packaging applications was investigated. In this area novel heat management packaging structures were obtained through the encapsulation of phase change materials (PCMs) within different polymeric matrices. The morphology, thermal properties, molecular organization and thermal energy storage ability of these capsules were evaluated. Afterwards, the encapsulation of bioactive ingredients for functional food applications was studied. In this field, novel micro- and nanoencapsulation structures were initially obtained through electrospraying from food contact materials. Finally, a vitamin and an antioxidant were encapsulated within different hydrocolloid matrices through electrospraying. Capsules attained were characterized and compared to those obtained through other encapsulation techniques. Moreover, stability of the encapsulated bioactives was studied under adverse conditions.<br>Pérez Masiá, R. (2014). MICRO- AND NANOENCAPSULATION VIA ELECTRO-HYDRODYNAMIC PROCESSING OF INTEREST IN FOOD APPLICATIONS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/39341<br>TESIS<br>Premiado

La présente thèse a été réalisée dans le cadre du projet de doctorat joint SMD-Tex, en partenariat entre le POLITO (Italie), l’ENSAIT (France) et à l'Université de Soochow (Chine). Le but de ce travail est de proposer de nouvelles approches pour la production de textiles biofonctionnels. Ces produits sont constitués de textiles qui ont subi des traitements de finition spéciaux pour conférer des propriétés qui présentent des effets bénéfiques pour la santé de l'utilisateur.Longtemps la recherche pharmaceutique a étudié des outils nouveaux et plus efficaces pour administrer un médicament au patient. Le but de ces études est d’admiistrer des dosages thérapeutiques efficaces sur une longue période, en minimisant le nombre d'administrations requises et les effets secondaires possibles. Dans ce contexte, la peau a été considérée comme une voie de libération de médicaments locaux et systémiques. Une telle approche est plus simple et moins invasive que d'autres voies. Donc, plusieurs stratégies ont été développées pour délivrer efficacement des médicaments à travers la barrière cutanée. Parmi celles-ci, la technologie d'encapsulation permet l'incorporation des substances actives à l'intérieur des nanoparticules (NP) pour i) protéger le médicament, ii) le délivrer efficacement à travers la peau iii) contrôler la libération au fil du temps.Dans le présent travail, des NP chargés de médicament ont été produits en utilisant de la polycaprolactone (PCL) comme membrane. Les nanoparticules produites ont ensuite été utilisées pour le finissage des tissus en coton produisant des textiles biofonctionnels destinés à être utilisés comme dispositifs portables de distribution de médicaments. La technique de nanoprécipitation flash (FNP) a été exploitée pour la production des NPs en raison de sa productivitè, et simplicité. La pertinence du procédé FNP pour produire des NP destinés à être utilisés dans la préparation de textiles biofonctionnels a été étudiée. Les nanoparticules PCL ont été produites en chargeant trois médicaments différents dans le système, à savoir la caféine, la mélatonine et la curcumine. Ces médicaments sont en effet considérés comme des médicaments modèles en termes de niveau d'hydrophilie. Ce dernier est une propriété clé dans la détermination du résultat du processus d'encapsulation et de la perméation cutanée.Le procédé FNP a été exécuté en dissolvant le polymère dans un solvant organique et en faisant entrer le courant de solution en collision avec un courant d'antisolvant dans un micromélangeur, entraînant la précipitation du polymère sous forme de nanoparticules. Pour chaque substance active, les protocoles expérimentaux et les méthodes analytiques ont été ajustés pour mieux étudier le système de NP chargé de médicament. L'effet de la formulation ainsi que les paramètres du procédé sur les taille et la capacité d’enrobement des nanoparticules ont été étudiés. De plus, les formulations de NP ont été caractérisées pour obtenir des informations sur leurs propriétés physiques et chimiques par diverses techniques. Les particules ont été appliquées au textile de coton soit par des méthodes d'imbibition ou d'imprégnation. L'efficacité du traitement de fonctionnalisation a été évaluée en combinant différentes analyses. Les propriétés biofonctionnelles ont été étudiées en termes d'activité antioxydante, de facteurs de protection UV et de libération de médicaments. Pour ce dernier test, la méthode des cellules de Franz a été employée. L'étude a montré que le FNP permet de produire des NPs de PCL chargées de médicament pour les trois substances étudiées. Le traitement de finition proposé a permis de fonctionnaliser efficacement la surface du tissu. Les textiles traités ont permis de délivrer efficacement les principes actifs à la peau avec des profils de perméation dépendant des propriétés du médicament. La finition des nanoparticules confère également au coton des propriétés antioxydantes et de protection contre les UV<br>This study was performed in the frame of the SMD-Tex Joint Doctorate project. The doctoral research activities were carried out in three mobility periods at POLITO (Italy), Ensait (France), and University of Soochow (China). This work aims to propose novel approaches for the production of biofunctional textiles. These products consist of textile fabrics which underwent special finishing treatments to confer properties that display beneficial effects to the user's health.In the last decades, pharmaceutical research has been investigating novel and more effective tools to administer a drug to the patient. The scope of these studies is to provide effective therapeutic dosages over a long time, minimizing the number of required administrations and the possible side effects. In this context, the skin has been regarded as a potential route for the release of local and systemic drugs. Such an approach is simpler and less invasive compared to other routes. Therefore, several strategies have been developed to effectively deliver drugs across the skin barrier. Among them encapsulation technology allows the incorporation of the active substances inside nanoparticles (NPs) to i) protect the drug, ii) effectively deliver it through the skin iii) control the release over time.In the present work, drug-loaded NPs were produced by employing polycaprolactone (PCL) as shell material. The produced nanoparticles were then used to finish cotton fabrics producing biofunctional textiles to be employed as wearable drug delivery devices. The flash nanoprecipitation technique (FNP) was exploited for the nanocarrier production being identified as a simple, sustainable and efficient production process. The suitability of the FNP process to produce NPs to be used in the preparation of biofunctional textiles was investigated. The PCL nanoparticles were produced by loading three different drugs in the system i.e. caffeine, melatonin, and curcumin. Such drugs are indeed considered model drugs in terms of hydrophilicity level. The latter is a key property in determining the outcome of the encapsulation process and the dermal permeation.The FNP process was run by dissolving the polymer in an organic solvent and making the solution stream collide against an antisolvent stream in a micromixer, resulting in the polymer precipitation in the form of nanoparticles. The drugs were precipitated together with the polymer upon being added either to the solvent or the antisolvent stream. For each active substance, the experimental protocols and analytical methods were adjusted to better investigated the drug-loaded NPs system. The effect of the formulation as well as the process parameters on the properties of the nanoparticles was investigated. The process was optimized to produce particles with a diameter lower than the one of skin pores. The amount of drug loaded in particles was investigated by loading capacity (LC) and encapsulation efficiency (EE). Furtherly, the NP formulations were characterized to obtain insights on their physical, chemical, and morphological properties by various analytical techniques.The particles were applied to the cotton fabric either by imbibition or impregnation methods. The effectiveness of the functionalization treatment was evaluated combining different analyses. The biofunctional properties were studied in terms of antioxidant activity, UV protection factors, and drug release. For the latter test, the Franz cell method was employed using either artificial and excised porcine skin membranes.The study showed that the FNP allows producing drug loaded PCL NPs for all the three investigated substances. The proposed finishing treatment allowed to effectively functionalize the fabric surface. The treated textiles allowed to effectively deliver the active principles to the skin with permeation profiles dependent on the drug properties. The nanoparticle finishing also imparted cotton antioxidant and UV protection properties

La persistance des biofilms reste un problème mondial rencontré dans l'industrie agro-alimentaire. En raison de la résistance adaptative associée aux propriétés physiques de la matrice du biofilm, l'échec de l'éradication totale des biofilms à l'aide de désinfectants conventionnels souligne la nécessité de trouver des stratégies alternatives efficaces. La méthodologie développée dans ce travail est axée sur l'utilisation de terpènes d'huiles essentielles biosourcées, à savoir le carvacrol (CAR) et le thymol (THY), qui représentent de puissants antimicrobiens face aux biofilms. La nanoencapsulation des terpènes est une approche innovante et proactive qui permet de stabiliser les terpènes et d'améliorer leurs fonctionnalités en les protégeant dans une structure d'enveloppe et en assurant une libération contrôlée rémanente. Les résultats de ce travail révèlent une plus grande activité du CAR et du THY nanoencapsulés contre les biofilms de Salmonella Enteritidis et Listeria innocua formés sur des surfaces en acier inoxydable (AI) par rapport à l'activité des terpènes libres. Les propriétés antimicrobiennes puissantes des nanocapsules ont été mises en évidence en induisant des dommages majeurs et évidents aux structures des cellules bactériennes avec une augmentation ultérieure de la perméabilité membranaire, favorisant la fuite des constituants vitaux intracellulaires vers le milieu extérieur. Après avoir confirmé l'activité antibiofilm prometteuse des nanocapsules monocouches (MC) obtenues par séchage par atomisation en utilisant de la maltodextrine comme matériau de support et le caséinate de sodium comme émulsifiant, un autre type de nanocapsules couche-par-couche (CPC) a été développé en ajoutant de la pectine comme couche interfaciale supplémentaire. L'augmentation de l'épaisseur de la structure interfaciale des capsules CPC a été observée au microscope et confirmée par l'augmentation de leur taille. La cinétique de relargage des terpènes des capsules MC et CPC suit un modèle mathématique de Korsmeyer-Peppas dominé par un mécanisme de diffusion Fickien. La libération du THY et du CAR à partir des capsules a montré un profil biphasique commençant par une libération initiale rapide des terpènes, suivie d'une deuxième phase de libération régulière pour les capsules MC, et d'une libération progressive et soutenue dans le temps pour les capsules CPC. Les activités antibiofilms des THY et CAR encapsulés sont cohérentes avec les courbes de libération, mettant en évidence une désinfection durable des surfaces en contact avec les aliments. Une exposition successive aux capsules MC et CPC a assuré une éradication de 99,99 % des biofilms avec une protection des surfaces d'AI contre la recontamination pendant plusieurs heures. L'inhibition a été induite par les nanocapsules MC qui ont assuré une désinfection initiale des surfaces avec une réduction des biofilms dans les premières minutes d'exposition, combinées aux capsules CPC qui ont continué à libérer des terpènes de manière contrôlée pendant plusieurs heures favorisant une désinfection prolongée des surfaces en contact avec les aliments et une protection contre la recontamination bactérienne. L'importante activité de désinfection rémanente obtenue par un traitement successif par des nanocapsules MC et CPC a également été validée sur des biofilms formés dans différentes conditions hydrodynamiques dans un système de canalisation de laboratoire reproduisant certaines des conditions d'écoulement réelles rencontrées dans les industries agro-alimentaires<br>The persistence of biofilms remains a worldwide problematic encountered in the agro-food industry. As a result of the adaptive resistance coupled with the physical properties of biofilm matrix, the failure to eradicate totally biofilms using conventional disinfectants urges the need to find alternative effective strategies. The current methodology developed in this work is focused on the use of biosourced essential oil terpenes, namely carvacrol (CAR) and thymol (THY) that represent powerful antimicrobial tools facing biofilms. Nanoencapsulation of terpenes is an innovative and proactive approach that stabilizes terpenes and enhances their functionalities by protecting them within a carrier shell structure and by ensuring a sustained controlled release. The results of this work reveal a greater activity of nanoencapsulated CAR and THY against Salmonella Enteritidis and Listeria innocua biofilms developed on stainless steel (SS) surfaces as compared to the activity of free terpenes. The potent antimicrobial prospects of nanocapsules were highlighted by inducing major obvious structural damages to bacterial cells with subsequent increase in permeability, promoting the leakage of intracellular vital constituents to the outer medium. After confirming the promising antibiofilm activity of monolayer (ML) nanocapsules developed by spray-drying using maltodextrin as carrier material and sodium caseinate as emulsifier, another layer-by-layer (LBL) nanocapsule was developed by adding pectin as an additional interfacial layer. The increased shell structure thickness of the LBL capsules was observed microscopically and confirmed by the increase in size. The release kinetics of terpenes from the ML and LBL capsules fitted into a Korsmeyer-Peppas mathematical model dominated by a Fickian-diffusion mechanism. The diffusion of THY and CAR out of the ML and LBL capsules was ascribed to a biphasic release profile starting with an initial rapid burst release of terpenes, followed by a second phase of steady release from the ML capsules compared to a gradual sustained release over time from the LBL capsules. The antibiofilm activities of encapsulated THY and CAR were consistent with the release curves, highlighting a promising sustained disinfection of food contact surfaces. A successive exposure to ML and LBL capsules ensured a 99.99 % eradication of biofilms with a protection of SS surfaces from recontamination for several hours. The inhibition was induced by the ML nanocapsules that ensured an initial disinfection of surfaces with a reduction of bacterial biofilms within the first exposure minutes, combined with the LBL capsules that kept releasing terpenes in a controlled manner over several hours favoring a sustained prolonged disinfection of food contact surfaces and a protection from bacterial recontamination. The prominent persistent disinfection activity using a successive treatment of ML and LBL nanocapsules was also validated on biofilms developed under different hydrodynamic conditions in a lab-scale pipeline system set-up to mimic some of the real flow conditions encountered in agro-food industries