Extended release of high pI proteins from alginate microspheres via a novel encapsulation technique

Wells, Laura; Sheardown, Heather

doi:10.1016/j.ejpb.2006.10.018

Cited by 99 publications

(41 citation statements)

References 31 publications

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“…Furthermore, alginate is an anionic polysaccharide and therefore electrostatic interactions (Draget, 2009) can occur in the presence of charged polymers (eg. cationic proteins such as Lf) leading to a sustained release of macromolecules from the gel particles Wells & Sheardown, 2007). Research has shown that electrostatic as well as other intermolecular interactions occur between Lf and alginate and that the extent of interactions is affected by the form of Lf (Bokkhim, Bansal, Grøndahl, & Bhandari, 2015;Peinado, Lesmes, Andr es, & McClements, 2010).…”

Section: Introductionmentioning

confidence: 99%

In-vitro digestion of different forms of bovine lactoferrin encapsulated in alginate micro-gel particles

2016

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Section: Introductionmentioning

confidence: 99%

In-vitro digestion of different forms of bovine lactoferrin encapsulated in alginate micro-gel particles

2016

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“…The gels are formed by exposing a NaAlg film or droplet to a solution containing an excess of the divalent cations. Ion-induced alginate gels have been used to immobilize cells [12][13][14], enzymes and proteins [15,16], microorganisms [17,18], pharmaceuticals [19,20], and inorganic solids [21][22][23]. Since the ionotropic gelation is very fast and the ability to control and modify the structure of the gel is limited, chemical modification [24,25] and blending with other materials [26][27][28] has been performed to overcome these disadvantages.…”

Section: Introductionmentioning

confidence: 99%

Rheology and Thermotropic Gelation of Aqueous Sodium Alginate Solutions

Florián‐Algarín

Acevedo

2010

J Pharm Innov

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In this work, we present the evaluation of the thermotropic gelling ability and steady-state rheology of aqueous sodium alginate (NaAlg) solutions. NaAlg is been considered due to its gelling capabilities and to determine its suitability as a film-forming agent with the potential capacity for immobilization of very potent, solid, and hydrophobic drugs. The existence of a thermally induced gelation of 1.0 to 2.5 wt.% sodium alginate solutions between 13°C to 22°C was demonstrated through three independent rheological tests: the constant-stress temperature-ramp viscosity, dynamic viscoelastic moduli, and thixotropy tests. Oscillatory dynamic tests also showed the thermoreversible nature of the NaAlg gels, but a large hysteresis between the gel formation and the gel melting was observed. The steady-state viscosity was experimentally determined as a function of shear rate for NaAlg concentrations between 1.0 to 2.5 wt.% and for temperatures from 20°C (or above T gel ) to 90°C. A viscosity master curve was constructed by applying time-temperature superposition and a semi-empirical shift factor for concentration. A power-law fluid modeladjusted to the data from 20°C to 60°C and found to provide good agreement with fitting parameters k=4.81 and n=−0.449±0.003.

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“…For substances of a hydrodynamic diameter larger than the pore sizes of the collapsed gel, their diffusion from the network is hindered 281 even though the electrostatic interactions are weakened as well. 139 This approach is assumed to result in an entrapment of the respective compound (see Figure 39b-i). In this case, leakage of the payload from the collapsed microgels at low pH values is prevented.…”

Section: P(hema-co-maa) Microgels: Loading and Release Of Myoglobinmentioning

confidence: 99%

“…be achieved via a post-formation pathway by exploiting the electrostatic interactions between anionic groups in the swollen gel network and positively charged macromolecules 139 or low molecular weight drugs. 140 An important factor to be considered is the careful adjustment of the pH of the microgel dispersion to guarantee an efficient loading.…”

Section: Temperature-sensitive Microgelsmentioning

confidence: 99%

Light-Sensitive Polymeric Nanoparticles Based on Photo-Cleavable Chromophores

Klinger

2013

Springer Theses

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This thesis focuses on the design, synthesis and characterization of novel photo-sensitive microgels and nanoparticles as potential materials for the loading and light-triggered release/accessibility of functional compounds. In order to realize this concept, different approaches to irradiation-dependent response mechanisms have been investigated.Novel light-cleavable divinyl functionalized monomeric crosslinkers based on o-nitrobenzyl derivatives were synthesized and used for the preparation of either PMMA or hydroxyl functionalized PHEMA microgels swellable and degradable in organic solvents. By the introduction of anionic MAA moieties into the PHEMA microgels, this concept was successfully transferred to double stimuli-responsive p(HEMA-co-MAA) hydrogel nanoparticles exhibiting a pH-dependent swelling and light-induced degradation behavior in aqueous media. This sensitivity to two orthogonal triggers is proposed to combine a pHinduced post-formation loading mechanism with a pH-and light-triggered release. In addition, a new class of enzyme-and light-sensitive PAAm microgels based on (meth-)acrylate functionalized dextrans as photo-and enzymatically degradable macromolecular crosslinkers was developed by introducing a photo-labile linker between the enzymatically degradable dextran chain and the polymerizable vinyl moieties. Here, the water solubility of the crosslinkers is assumed to enable an in situ loading approach of hydrophilic compounds.A different approach to the loading of microgels is based on photo-labile covalent microgel-drug conjugates. The first step to the realization of this concept was achieved by the development of a novel functional monomer consisting of a doxorubicin molecule covalently attached to a radically polymerizable methacrylate group via a photo-cleavable linker.Moreover, in order to enable the release of hydrophobic substances in aqueous media, hydrophobic nanoparticles consisting of a photo-resist polymer were designed to be degradable upon irradiation in water. Light-triggered conversion of the initial hydrophobic polymer into hydrophilic PMAA induced in situ particle dissolution and release of nile red.Since the introduction of a stimuli-responsive shell around a microgel is assumed to prevent leakage of embedded compounds, studies on non-stimuli-responsive shell formation around preformed microgel seed particles and the formation of microgel cores in polymeric shells were conducted to investigate potential synthetic pathways to this approach.In a last attempt, the surface of PHEMA and p(HEMA-co-MAA) microgels was functionalized with cinnamoyl groups in order to trigger the (reversible) particles interaction with each other by light-induced [2+2] cycloaddition reactions.

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Extended release of high pI proteins from alginate microspheres via a novel encapsulation technique

Cited by 99 publications

References 31 publications

In-vitro digestion of different forms of bovine lactoferrin encapsulated in alginate micro-gel particles

In-vitro digestion of different forms of bovine lactoferrin encapsulated in alginate micro-gel particles

Rheology and Thermotropic Gelation of Aqueous Sodium Alginate Solutions

Light-Sensitive Polymeric Nanoparticles Based on Photo-Cleavable Chromophores

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