Formation of liquid core–polymer shell microcapsules

Yow, Huai Nyin; Routh, Alexander F.

doi:10.1039/b606965g

Cited by 337 publications

(261 citation statements)

References 71 publications

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“…MIPs are stable against mechanical stress, elevated temperatures, and high pressures, resistant against treatments with acids, bases, and in a wide range of solvent. 48,49 In that respect, MIPs containers would have a competitive advantage over current releasing technologies using brittle or soft materials such as hollow microcapsules with liquid cores, 50,51 or liposomes. 52 However, in order to use the specificity of the MIP cavities as a driving force for controlling the releasing rate, the affinity and capacity of the best binding sites needs to be significantly improved.…”

Section: Applicability Of Mips As Reservoirs Of Active Substancesmentioning

confidence: 99%

Influence of Polymer Morphology on the Capacity of Molecularly Imprinted Resins to Release or to Retain their Template

et al. 2009

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This paper deals with the specific ability of molecularly imprinted polymers (MIPs) to release and/or to retain their template. MIPs for caffeine with various MIP:porogen volume ratios were prepared by a non-covalent route. Formation of a prepolymerization complex between the template and the functional monomer was confirmed by nuclear magnetic resonance and computer simulation. The MIP monoliths were successively grinded, sieved, and dried under vacuum. The morphology of the imprinted particles was investigated by scanning electron microscopy, swelling experiments and nitrogen adsorption. Typical release patterns of as-synthesised MIP particles in solvents can be decomposed in three fractions: initial release ( 0 ), slow release over several hours (Á Release ), permanent retention/encapsulation within the MIP (Á Reservoir ). The effect of MIP:porogen volume ratio (related to the MIP porosity) on the releasing/retaining profiles of the materials has been investigated. Finally, the results were critically compared with the available literature and the applicability of MIP reservoirs is briefly discussed.KEY WORDS: Molecular Imprinting / Polymer Morphology / Controlled Release / Polymer Reservoir / Self-Assembly / Molecular imprinting is an emerging technology, which allows the molecular design of polymeric materials containing highly specific receptor sites with an affinity for target compounds.1-3 Formation of a self-assembled pre-polymerization complex between a template molecule and functional monomers, followed by polymerization with a cross-linker in a porogenic solvent and the subsequent extraction of the template, produces a molecularly imprinted polymer (MIP) possessing specifically sized and shaped cavities capable of molecular recognition. 4,5 MIPs are generally highly crosslinked thermosets, and therefore porosity is a necessary feature of their morphology to allow permeability and transport of templates molecules to the bulk polymer phase.To date, a number of promising applications have been proposed for MIPs. For instance, imprinted polymers are used in chromatography as the stationary phase for separation and isolation of racemates.6,7 A related area is solid-phase extraction, where imprinted polymers are employed as a selective sorbent to concentrate the molecule of interest.8 MIPs are also used in immunoassays-type analyses as synthetic antibody 9 and in catalysis as enzyme mimics. 10,11 In the emerging field of biosensors, MIPs demonstrate a potential as the recognition element, although their performance and selectivity in aqueous systems is still a limiting factor. 12,13The application of desorption properties of MIPs is a relatively new area.14,15 Chromatographic data have shown that the MIP-template dissociation kinetics can be controlled by varying the local environment (MIP composition, solvent. . .). Therefore, it seems feasible that MIPs could form highly specific rate limiting reservoirs releasing active compounds at well-defined rates. Early studies delivered promising results and showe...

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Section: Applicability Of Mips As Reservoirs Of Active Substancesmentioning

confidence: 99%

Influence of Polymer Morphology on the Capacity of Molecularly Imprinted Resins to Release or to Retain their Template

et al. 2009

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“…% Cumulative release of risedronate from aqueous core-PLGA shell microcapsules and PLGA microspheres in PBS (pH 6.8). Data are given as mean±standard deviation (SD); n=3 for each time point in both curves; ns represents no significant difference at p<0.05 using two-way ANOVA with Bonferroni's multiple comparisons test poly(methyl methacrylate), and poly(isobutyl methacrylate) polymers (10,20).…”

Section: Discussionmentioning

confidence: 99%

Synthesis and Characterization of PLGA Shell Microcapsules Containing Aqueous Cores Prepared by Internal Phase Separation

Abulateefeh

Alkilany

2015

AAPS PharmSciTech

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Abstract. The preparation of microcapsules consisting of poly(D,L-lactide-co-glycolide) (PLGA) polymer shell and aqueous core is a clear challenge and hence has been rarely addressed in literature. Herein, aqueous core-PLGA shell microcapsules have been prepared by internal phase separation from acetonewater in oil emulsion. The resulting microcapsules exhibited mean particle size of 1.1±0.39 μm (PDI=0.35) with spherical surface morphology and internal poly-nuclear core morphology as indicated by scanning electron microscopy (SEM). The incorporation of water molecules into PLGA microcapsules was confirmed by differential scanning calorimetry (DSC). Aqueous core-PLGA shell microcapsules and the corresponding conventional PLGA microspheres were prepared and loaded with risedronate sodium as a model drug. Interestingly, aqueous core-PLGA shell microcapsules illustrated 2.5-fold increase in drug encapsulation in comparison to the classical PLGA microspheres (i.e., 31.6 vs. 12.7%), while exhibiting sustained release behavior following diffusion-controlled Higuchi model. The reported method could be extrapolated to encapsulate other water soluble drugs and hydrophilic macromolecules into PLGA microcapsules, which should overcome various drawbacks correlated with conventional PLGA microspheres in terms of drug loading and release.

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“…In addition to that, we resolve the effect of an explicit coupling zone (co) connecting these two components. These coupling zones may be intentionally fabricated [44,45] or they may arise during the manufacturing process if the matrix material on the inclusion surfaces behaves differently from the bulk of the matrix [2,22,23].…”

Section: Macroscopic Variablesmentioning

confidence: 99%

Hydrodynamic description of elastic or viscoelastic composite materials: Relative strains as macroscopic variables

Menzel

2016

Phys. Rev. E

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One possibility to adjust material properties to a specific need is to embed units of one substance into a matrix of another substance. Even materials that are readily tunable during operation can be generated in this way. In (visco)elastic substances, both the matrix material as well as the inclusions and/or their immediate environment can be dynamically deformed. If the typical dynamic response time of the inclusions and their surroundings approach the macroscopic response time, their deformation processes need to be included into a dynamic macroscopic characterization. Along these lines, we present a hydrodynamic description of (visco)elastic composite materials. For this purpose, additional strain variables reflect the state of the inclusions and their immediate environment. These additional strain variables in general are not set by a coarse-grained macroscopic displacement field. Apart from that, during our derivation, we also include the macroscopic variables of relative translations and relative rotations that were previously introduced in different contexts. As a central point, our approach reveals and classifies the importance of a new macroscopic variable: relative strains. We analyze two simplified minimal example geometries as an illustration.

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Formation of liquid core–polymer shell microcapsules

Cited by 337 publications

References 71 publications

Influence of Polymer Morphology on the Capacity of Molecularly Imprinted Resins to Release or to Retain their Template

Influence of Polymer Morphology on the Capacity of Molecularly Imprinted Resins to Release or to Retain their Template

Synthesis and Characterization of PLGA Shell Microcapsules Containing Aqueous Cores Prepared by Internal Phase Separation

Hydrodynamic description of elastic or viscoelastic composite materials: Relative strains as macroscopic variables

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