Nanocomposite capsules with directional, pulsed nanoparticle release

Udoh, Christiana E.; Cabral, João T.; Garbin, Valeria

doi:10.1126/sciadv.aao3353

Cited by 19 publications

(23 citation statements)

References 46 publications

(50 reference statements)

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“…Our observations with PVA solutions qualitatively agree with previous work on NaPSS and nanoparticle composites. 50…”

Section: Resultsmentioning

confidence: 99%

“…In droplet extraction, in addition to dissolution, internal convection, phase separation and inversion, interfacial tension and polymer enrichment at the surface are all expected to play a role in the shrinkage profile. We therefore employ a minimal descriptive model, introduced previously, 35,36,50 to parameterise droplet shrinkage and particle formation:…”

Section: Parameterisation Of the Extraction Processmentioning

confidence: 99%

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Microfluidic solvent extraction of poly(vinyl alcohol) droplets: effect of polymer structure on particle and capsule formation

et al. 2018

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We investigate the formation of poly(vinyl alcohol) microparticles by the selective extraction of aqueous polymer solution droplets, templated by microfluidics and subsequently immersed in a non-solvent bath. The role of polymer molecular mass (18-105 kg mol-1), degree of hydrolysis (88-99%) and thus solubility, and initial solution concentration (0.01-10% w/w) are quantified. Monodisperse droplets with radii ranging from 50 to 500 μm were produced at a flow-focusing junction with carrier phase hexadecane and extracted into ethyl acetate. Solvent exchange and extraction result in droplet shrinkage, demixing, coarsening and phase-inversion, yielding polymer microparticles with well-defined dimensions and internal microstructure. Polymer concentration, varied from below the overlap concentration c* to above the concentrated crossover c**, as estimated by viscosity measurements, was found to have the largest impact on the final particle size and extraction timescale, while polymer mass and hydrolysis played a secondary role. These results are consistent with the observation that the average polymer concentration upon solidification greatly exceeds c**, and that the internal microparticle porosity is largely unchanged. However, reducing the initial polymer concentration to well below c* (approximately 100×) and increasing droplet size yields thin-walled (100's of nm) capsules which controllably crumple upon extraction. The symmetry of the process can be readily broken by imposing extraction conditions at an impermeable surface, yielding large, buckled, cavity morphologies. Based on these results, we establish robust design criteria for polymer capsules and particles, demonstrated here for poly(vinyl alcohol), with well-defined shape, dimensions and internal microstructure.

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“…Our observations with PVA solutions qualitatively agree with previous work on NaPSS and nanoparticle composites. 50…”

Section: Resultsmentioning

confidence: 99%

Section: Parameterisation Of the Extraction Processmentioning

confidence: 99%

Microfluidic solvent extraction of poly(vinyl alcohol) droplets: effect of polymer structure on particle and capsule formation

et al. 2018

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“…Internal convection is observed within droplets, in particular for the faster extractions ( Supplementary Information movie S1). The external morphology of capsules obtained using MEK appears somewhat crumpled, which is expected for fast extractions (higher Pe) and shell formation at earlier times, 21 followed by subsequent buckling upon continuous solvent removal. Buckling is driven by the unconstrained decrease in compressive stresses generated on the shell wall during droplet volume reduction.…”

Section: Extraction Data Analysis and Descriptive Modelmentioning

confidence: 94%

“…During release, the capsule's scaffold retains its integrity, thereby enabling the multiple bursts from internal compartments over time. 21 Core-shell capsules, formed by BA extraction, possessing a large single compartment filled with nanoparticle clusters, releases from only one active site and in a single burst, at a comparatively shorter time (Supplementary Information movie S6). We estimate nanoparticle cluster release from active sites of EA and BA capsules (indicated in Fig.…”

Section: Capsule Microstructure: Correlation Between Extraction Solvementioning

confidence: 99%

“…Internally bicontinuous capsules were found to exhibit pulsed cargo release, in a series of bursts. 21 Here, we seek to elucidate the role of the extraction solvent in modulating microcapsule architecture and, in turn, the release mechanism and kinetics of nanoparticle cargo. We therefore investigate a series of extraction solvents and carry out a comparative study of their effect in both capsule format and dissolution.…”

Section: Introductionmentioning

confidence: 99%

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Polymer nanocomposite capsules formed by droplet extraction: spontaneous stratification and tailored dissolution

2019

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One-Step Dynamic Imine Chemistry for Preparation of Chitosan-Stabilized Emulsions Using a Natural Aldehyde: Acid Trigger Mechanism and Regulation and Gastric Delivery

Chen

Zhao

et al. 2020

J. Agric. Food Chem.

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Chitosan is a polysaccharide widely used as a structuring agent in foods and other materials because of its positive charge (amino groups). At present, however, it is difficult to form and stabilize emulsions using chitosan due to its high hydrophilicity. In this study, oil-in-water emulsions were prepared using a one-pot green-chemistry method. The chitosan and aldehyde molecules were in situ interfacially conjugated during homogenization, which promoted the adsorption of chitosan onto the oil droplet surfaces where they created a protective coating. The universality of this method was verified by using chitosan with different molecular weights and four kinds of natural aldehydes [cinnamaldehyde (CA), citral (CT), citronella (CN), and vanillin (VL)]. Chitosan with higher molecular weight facilitated the formation of emulsions. By harnessing the dynamic covalent nature of imine bonds, chitosan emulsions with an imine link display dynamic behavior with acid-catalyzed hydrolysis. The aldehyde structure could control the pH point of trigger for breakdown of emulsions, which was 1.0, 3.0, 4.0, and 4.0 for CA emulsion, CT emulsion, CN emulsion, and VL emulsion, respectively. At pH 6.5, aldehyde helped to decrease the interfacial tension of chitosan to about 10 mN/m, while this value would increase if the pH decreased by adding acid during the measurement. Chemical kinetics studies indicated that the hydrophobicity and conjugation effect of the aldehyde together determined the trigger points and properties of the emulsion. Finally, we used the optimized emulsions to encapsulate and control the release of curcumin. The gastric release behavior of the curcumin depended on aldehyde structure: VL > CN > CT ≈ CA. Hence, a tailor-made trigger release emulsion system can be achieved by rational selection and design of aldehyde structure to control hydrophobicity and conjugation effect of aldehydes.

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Nanocomposite capsules with directional, pulsed nanoparticle release

Abstract: Nanocomposite microcapsules with bicontinuous internal morphology release nanoparticles in directional bursts.

Cited by 19 publications

References 46 publications

Microfluidic solvent extraction of poly(vinyl alcohol) droplets: effect of polymer structure on particle and capsule formation

Microfluidic solvent extraction of poly(vinyl alcohol) droplets: effect of polymer structure on particle and capsule formation

Polymer nanocomposite capsules formed by droplet extraction: spontaneous stratification and tailored dissolution

One-Step Dynamic Imine Chemistry for Preparation of Chitosan-Stabilized Emulsions Using a Natural Aldehyde: Acid Trigger Mechanism and Regulation and Gastric Delivery

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