Impact of electrostatic potential on microcapsule-formation and physicochemical analysis of surface structure:Implications for therapeutic cell-microencapsulation

Cell-encapsulation is used for preventing therapeutic cells from being rejected by the host. The technology to encapsulate cells in immunoprotective biomaterials, such as alginate, commonly involves application of an electrostatic droplet generator for reproducible manufacturing droplets of similar size and with similar surface properties. As many factors influencing droplet formation are still unknown, we investigated the impact of several parameters and fitted them to equations to make procedures more reproducible and allow optimal control of capsule size and properties. We demonstrate that droplet size is dependent on an interplay between the critical electric potential (Uc,), the needle size, and the distance between the needle and the gelation bath, and that it can be predicted with the equations proposed. The droplet formation was meticulously studied and followed by a high-speed camera. The X-ray photoelectron analysis demonstrated optimal gelation and substitution of sodium with calcium on alginate surfaces while the atomic force microscopy analysis demonstrated a low but considerable variation in surface roughness and low surface stiffness. Our study shows the importance of documenting critical parameters to guarantee reproducible manufacturing of beads with constant and adequate size and preventing batch-to-batch variations

Discovering NDM-1 inhibitors using molecular substructure embeddings representations

NDM-1 (New-Delhi-Metallo-beta-lactamase-1) is an enzyme developed by bacteria that is implicated in bacteria resistance to almost all known antibiotics. In this study, we deliver a new, curated NDM-1 bioactivities database, along with a set of unifying rules for managing different activity properties and inconsistencies. We define the activity classification problem in terms of Multiple Instance Learning, employing embeddings corresponding to molecular substructures and present an ensemble ranking and classification framework, relaying on a k-fold Cross Validation method employing a per fold hyper-parameter optimization procedure, showing promising generalization ability. The MIL paradigm displayed an improvement up to 45.7 %, in terms of Balanced Accuracy, in comparison to the classical Machine Learning paradigm. Moreover, we investigate different compact molecular representations, based on atomic or bi-atomic substructures. Finally, we scanned the Drugbank for strongly active compounds and we present the top-15 ranked compounds

Structure, controlled release mechanisms and health benefits of pectins as an encapsulation material for bioactive food components

Encapsulation of food and feed ingredients is commonly applied to avoid the loss of functionality of bioactive food ingredients. Components that are encapsulated are usually sensitive to light, pH, oxygen or highly volatile. Also, encapsulation is also applied for ingredients that might influence taste. Many polymers from natural sources have been tested for encapsulation of foods. In the past few years, pectins have been proposed as emerging broadly applicable encapsulation materials. The reasons are that pectins are versatile and inexpensive, can be tailored to meet specific demands and provide health benefits. Emerging new insight into the chemical structure and related health benefits of pectins opens new avenues to use pectins in food and feed. To provide insight into their application potential, we review the current knowledge on the structural features of different pectins, their production and tailoring process for use in microencapsulation and gelation, and the impact of the pectin structure on health benefits and release properties in the gut, as well as processing technologies for pectin-based encapsulation systems with tailor-made functionalities. This is reviewed in view of application of pectins for microencapsulation of different sensitive food components. Although some critical factors such as tuning of controlled release of cargo in the intestine and the impact of the pectin production process on the molecular structure of pectin still need more study, current insight is that pectins provide many advantages for encapsulation of bioactive food and feed ingredients and are cost-effective

Encapsulation de systèmes enzymatiques d'intérêt alimentaire

NANCY-INPL-Bib. électronique (545479901) / SudocSudocFranceF

Multienzymatic system encapsulation: Application to the lactoperoxidase system

The use of enzyme often implicates a stabilization to limit loss of activity and a suitable dry formulation to simplify handling. Freeze drying and spray drying are two classic methods but when complex systems are studied, it becomes difficult to achieve a correct formulation. In this work, the realization of a dry microbead containing a multienzymatic system (2 enzymes, 2 substrates) is presented. The lactoperoxidase system associated with an enzymatic hydrogen peroxide generator was chosen as the model. The microbead, made by spray drying and spray coating, was characterized in terms of size, shape, chemical structure, flow ability, encapsulation efficiency and antimicrobial activity. Different compositions of the coat were tested, as well as their influence on the bead properties

Microencapsulation par évaporation de solvant

The solvent evaporation encapsulation technique is widely used in the pharmaceutical applications for the controlled release of active principle (drug). The organic phase, which comprises solvent, polymer and active principle, is dispersed into an aqueous phase. The solvent diffuses into the latter one and then evaporates, leading consequently to the formation of solid polymer microspheres with active principle trapped inside. Contrary to most studies on the polymer choice and drug release, our study focused on the process-engineering aspects in the production of microspheres in order to optimize the process duration and analyze the influence the properties of obtained microspheres. The evaporation of solvent has been studies with different operating conditions (temperature, pressure, quantity of materials). The reduced pressure (60% of atmospheric pressure) has shown the most significant effect, which reduced the process duration to 1/3. The physical properties of the obtained microspheres (size, surface and inner structure) were examined. The investigation of the inner structure of microspheres by a novel technique X-ray tomography showed the size and location of pores. Microspheres produced under reduced pressure show smaller size, smoother surface and less porous structure. The study was then carried out at a microscopic scale on the solidification of one single drop of the dispersed phase. The mass transfer of the solvent at the interface of two phases was investigated with interferometer, which measured the variations of solvent concentration and the diffusion boundary layer with time. Our work enables to complete the knowledge of this process and propose the directions of future developments on the processLa technique d encapsulation par évaporation de solvant est largement utilisée dans des applications pharmaceutiques pour la libération contrôlée du principe actif (médicament). La phase organique constituée de solvant, de polymère et de principe actif est dispersée dans une phase aqueuse. Le solvant diffuse dans cette dernière et puis il s'évapore, ce qui conduit à la formation des microsphères solides de polymère contenant du principe actif à l intérieur. Contrairement à la plupart des études consacrées au choix des polymères et aux tests de libération, notre étude s est intéressée aux aspects d'ingénierie afin d optimiser la durée du procédé et d analyser l'influence des conditions opératoires sur les propriétés des microsphères. L'évaporation du solvant a été étudiée pour de différentes conditions (température, pression, quantités des matériaux). La durée de procédé a été réduite à 1/3 en appliquant une faible pression (60% de la pression atmosphérique). Les propriétés des microsphères obtenues (taille, surface et structure interne) ont été examinées. L analyse de la structure interne des microsphères par la nouvelle technique de tomographie à rayons X a montré la taille des pores et de l'emplacement des pores. L étude a été effectuée ensuite à l échelle microscopique sur la solidification d une goutte de la phase dispersée. Le transfert de masse du solvant a été étudié avec l'interféromètre, permettant de mesurer la variation de concentration du solvant et l épaisseur de la couche limite diffusive. Notre travail a permis de combler les lacunes dans la connaissance de ce procédé et il propose des pistes de développement du procédéNANTES-BU Sciences (441092104) / SudocSudocFranceF

Oil encapsulation techniques using alginate as encapsulating agent: applications and drawbacks

International audienceOils are used in agriculture, nutrition, food and cosmetics; however, these substances are oxidisable and may readily lose their properties. To reduce their degradation or to mask certain undesirable aspects, one strategy consists in encapsulating the oil in inert structures (capsules). The capsules are classified according to the morphology, the number of cores and size, can be produced by several techniques: jet-cutting, vibrating jet, spray-drying, dispersion and milli-microfluidic. Among the polymers used as a membrane in the capsules, alginates are used in oil encapsulation because of their high gelling capacity, biocompatibility and low toxicity. In the presence of calcium ions, the alginate macromolecules crosslink to form a three-dimensional network called hydrogel. The oil encapsulation using alginate as encapsulating material can be carried out using technologies based on the external, internal or inverse gelation mechanisms. These capsules can found applications in areas as cosmetics, textile, foods and veterinary, for example