Novel pH-sensitive microgels prepared using salt bridge

Xia, Yang; Kim, Jin‐Chul

doi:10.1016/j.ijpharm.2009.12.035

Cited by 22 publications

(5 citation statements)

References 25 publications

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“…The final swelling ratios were 30.11%, 91.19%, 123.73% for pHs of 2.5, 7, and 10, respectively. Results indicated that swelling ratio was influenced by solution pH with greater swelling at higher pH, consistent with published literature (Gunasekaran and others 2007; Yang and Kim 2010). The final values of the swelling ratios showed higher variations due to decreased integrity of the gel.…”

Section: Resultssupporting

confidence: 90%

Magnetic Resonance Imaging (MRI) and Relaxation Spectrum Analysis as Methods to Investigate Swelling in Whey Protein Gels

Öztop¹,

Rosenberg²,

Rosenberg³

et al. 2010

Journal of Food Science

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Effective means for controlled delivery of nutrients and nutraceuticals are needed. Whey protein-based gels, as a model system and as a potential delivery system, exhibit pH-dependent swelling when placed in aqueous solutions. Understanding the physics that govern gel swelling is thus important when designing gel-based delivery platforms. The extent of swelling over time was monitored gravimetrically. In addition to gravimetric measurements, magnetic resonance imaging (MRI) a real-time noninvasive imaging technique that quantified changes in geometry and water content of these gels was utilized. Heat-set whey protein gels were prepared at pH 7 and swelling was monitored in aqueous solutions with pH values of 2.5, 7, and 10. Changes in dimension over time, as characterized by the number of voxels in an image, were correlated to gravimetric measurements. Excellent correlations between mass uptake and volume change (R(2)= 0.99) were obtained for the gels in aqueous solutions at pH 7 and 10, but not for gels in the aqueous solution at pH 2.5. To provide insight into the mechanisms for water uptake, nuclear magnetic resonance (NMR) relaxation times were measured in independent experiments. The relaxation spectrum for the spin-spin relaxation time (T(2)) showed the presence of 3 proton pools for pH 7 and 10 trials and 4 proton pools for pH 2.5 trials. Results demonstrate that MRI and NMR relaxation measurements provided information about swelling in whey protein gels that can constitute a new means for investigating and developing effective delivery systems for foods.

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Section: Resultssupporting

confidence: 90%

Magnetic Resonance Imaging (MRI) and Relaxation Spectrum Analysis as Methods to Investigate Swelling in Whey Protein Gels

Öztop¹,

Rosenberg²,

Rosenberg³

et al. 2010

Journal of Food Science

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“…These properties render polysaccharide-based microgels most suited for numerous applications in biotechnological and biomedical applications. These include the immobilization of DNA in hyaluronic acid microgels serving as an experimental platform with cell-mimicking properties [4,5], the trapping of biomolecules like enzymes in agarose-based microgels [6], the delivery of compounds via carboxymethylcellulose-based microgels [7], and cell culturing inside hyaluronic acid- and heparin-based microgels by attaching cell binding sites such as fibrinogen, the tripeptide sequence of arginine, glycine, and aspartate (RGD), as well as others [8,9]. While copper(I)-catalyzed azide-alkyne click chemistry [10,11], Diels-Alder cycloaddition [12,13], and the thiol-Michael addition reaction [14,15,16] have been employed for fabricating polysaccharide microgels in quantitative yield and under mild conditions, introducing multi-functionality in these materials usually requires elaborate chemical pre-modifications of the polysaccharide-based gel building blocks.…”

Section: Introductionmentioning

confidence: 99%

Droplet-Assisted Microfluidic Fabrication and Characterization of Multifunctional Polysaccharide Microgels Formed by Multicomponent Reactions

et al. 2018

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Polysaccharide-based microgels have broad applications in multi-parametric cell cultures, cell-free biotechnology, and drug delivery. Multicomponent reactions like the Passerini three-component and the Ugi four-component reaction are shown in here to be versatile platforms for fabricating these polysaccharide microgels by droplet microfluidics with a narrow size distribution. While conventional microgel formation requires pre-modification of hydrogel building blocks to introduce certain functionality, in multicomponent reactions one building block can be simply exchanged by another to introduce and extend functionality in a library-like fashion. Beyond synthesizing a range of polysaccharide-based microgels utilizing hyaluronic acid, alginate and chitosan, exemplary in-depth analysis of hyaluronic acid-based Ugi four-component gels is conducted by colloidal probe atomic force microscopy, confocal Brillouin microscopy, quantitative phase imaging, and fluorescence correlation spectroscopy to elucidate the capability of microfluidic multicomponent reactions for forming defined polysaccharide microgel networks. Particularly, the impact of crosslinker amount and length is studied. A higher network density leads to higher Young’s moduli accompanied by smaller pore sizes with lower diffusion coefficients of tracer molecules in the highly homogeneous network, and vice versa. Moreover, tailored building blocks allow for crosslinking the microgels and incorporating functional groups at the same time as demonstrated for biotin-functionalized, chitosan-based microgels formed by Ugi four-component reaction. To these microgels, streptavidin-labeled enzymes are easily conjugated as shown for horseradish peroxidase (HRP), which retains its activity inside the microgels.

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“…However, when the electrostatic interactions are repulsive the biopolymer chains attempt to get as far away from each other as possible, and so the pore size becomes relatively large, leading to bead swelling. Changes in the degree of swelling of microgels due to electrostatic interactions can therefore be used to create pH-or salt-induced triggered release of bioactive components [168,195,196].…”

Section: Swellingmentioning

confidence: 99%

Designing biopolymer microgels to encapsulate, protect and deliver bioactive components: Physicochemical aspects

McClements

2017

Advances in Colloid and Interface Science

211

125

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Biopolymer microgels have considerable potential for their ability to encapsulate, protect, and release bioactive components. Biopolymer microgels are small particles (typically 100nm to 1000μm) whose interior consists of a three-dimensional network of cross-linked biopolymer molecules that traps a considerable amount of solvent. This type of particle is also sometimes referred to as a nanogel, hydrogel bead, biopolymer particles, or microsphere. Biopolymer microgels are typically prepared using a two-step process involving particle formation and particle gelation. This article reviews the major constituents and fabrication methods that can be used to prepare microgels, highlighting their advantages and disadvantages. It then provides an overview of the most important characteristics of microgel particles (such as size, shape, structure, composition, and electrical properties), and describes how these parameters can be manipulated to control the physicochemical properties and functional attributes of microgel suspensions (such as appearance, stability, rheology, and release profiles). Finally, recent examples of the utilization of biopolymer microgels to encapsulate, protect, or release bioactive agents, such as pharmaceuticals, nutraceuticals, enzymes, flavors, and probiotics is given.

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Novel pH-sensitive microgels prepared using salt bridge

Cited by 22 publications

References 25 publications

Magnetic Resonance Imaging (MRI) and Relaxation Spectrum Analysis as Methods to Investigate Swelling in Whey Protein Gels

Magnetic Resonance Imaging (MRI) and Relaxation Spectrum Analysis as Methods to Investigate Swelling in Whey Protein Gels

Droplet-Assisted Microfluidic Fabrication and Characterization of Multifunctional Polysaccharide Microgels Formed by Multicomponent Reactions

Designing biopolymer microgels to encapsulate, protect and deliver bioactive components: Physicochemical aspects

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