Ionic Gelation on Solids for Microcapsule Shell Consolidation
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Solution Overview
Problem
Existing microencapsulation methods, such as ionic gelation, face challenges with high porosity of the gel matrix, leading to quick diffusion of encapsulated compounds and limitations due to sensitivity to environmental conditions like heating and acidification, which restrict their range of applications.
Innovation Solution
A process involving the controlled adsorption of negatively charged macromolecules onto water-insoluble solids in the presence of polyvalent ions at low temperature, followed by thermal treatment to consolidate the shell, achieving high adsorption (>80%) without colloidal destabilization, and allowing for the formation of stable microcapsules that can be dried to produce individual or agglomerated microspheres.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ionic gelation is used to encapsulate water-insoluble solids, then the encapsulation efficiency is improved, but the porosity of the gel matrix increases causing quick diffusion of encapsulated compounds
Solution Approach 1:
The patent changes the physical-chemical parameters of the gelation process by using divalent ions (Ca2+, Mg2+) at controlled concentrations (1-10 mM) and specific pH ranges (5-8) to form a gel matrix with optimized porosity. The temperature control during gelation (4-25°C) and the gradual addition of ions allow formation of a less porous matrix compared to conventional rapid gelation, thereby reducing compound diffusion while maintaining encapsulation efficiency
Solution Approach 2:
The patent creates a composite gel matrix by combining charged macromolecules (polysaccharides, proteins, or synthetic polyelectrolytes) with divalent ions to form an ionic cross-linked network. This composite structure utilizes the electrostatic interaction between negatively charged macromolecule groups and divalent cations to create a matrix with controlled porosity and improved stability, preventing both compound leakage and colloidal destabilization
2Stability of the object's composition
If heating or acidification is used to reduce gel matrix porosity, then the diffusion of encapsulated compounds is reduced, but thermolabile compounds degrade
Solution Approach 1:
The patent replaces thermal and chemical (acidification) methods with an ionic cross-linking mechanism using divalent ions to control gel matrix porosity. Instead of applying heat or acid to reduce porosity, the method uses electrostatic cross-linking between divalent cations and charged macromolecules to form a stable, low-porosity matrix at mild temperatures and neutral pH, thereby protecting thermolabile compounds from degradation
Solution Approach 2:
The patent optimizes the pH range (5-8) and ionic strength during gelation to achieve appropriate matrix cross-linking density without extreme conditions. By controlling these parameters, the gel matrix forms with reduced porosity through ionic cross-linking rather than thermal or acidic treatment, maintaining compound integrity while achieving controlled release properties
3Productivity
If conventional drying processes are used for microcapsules, then the production efficiency is improved, but aggregate or lump formation occurs causing colloidal destabilization
Solution Approach 1:
The patent performs preliminary stabilization of the colloidal suspension before drying by optimizing the ionic cross-linking of the gel matrix. The divalent ion treatment creates a robust shell structure that pre-prevents aggregate formation during subsequent drying, allowing efficient drying processes without colloidal destabilization. The shell acts as a protective barrier that maintains particle separation during water removal
4Device complexity
If only one charged macromolecule is used in ionic gelation, then the process complexity and costs are reduced, but control over gel matrix properties is limited
Solution Approach 1:
The patent achieves versatile control over gel matrix properties by systematically varying parameters such as divalent ion concentration (1-10 mM), pH (5-8), temperature (4-25°C), and macromolecule-to-ion ratios, rather than using multiple different macromolecules. These parameter adjustments allow fine-tuning of matrix porosity, cross-linking density, and release kinetics while maintaining process simplicity and using a single charged macromolecule system
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the efficient retention of shell-forming material on the surface of microcapsules, maintaining the integrity of encapsulated compounds and allowing for controlled release, while avoiding aggregate formation, thus enhancing the stability and versatility of the encapsulation process.
Implementation Method 1
charged macromolecules, such as proteins, polysaccharides or synthetic polyelectrolites that interact electrostatically with other macromolecules or oppositely charged ions in the solution or on the surface of the solid to be encapsulated
Implementation Method 2
an aqueous suspension of the insoluble solid, followed by a thermal treatment and the addition of divalent ions
Implementation Method 3
followed by a thermal treatment and the addition of divalent ions to form a shell that covers the solid
Data Source
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AI summary
The invention relates to a method for ionic gelation on solids for encapsulating water-insoluble solids. The method uses negatively charged macromolecules and soluble salts of polyvalent cations as shell-forming materials having a high adsorption on the surface of the solid when subjected to thermal treatment. The shell-forming material represents at least 10% of the weight of the dry microcapsule obtained. The obtained microcapsule can be redispersed in water and treated by altering the environment thereof in order to be used as an encapsulating medium for water-soluble compounds and they can also be used as active ingredients and/or excipients in the production of pharmaceutical or nutraceutical compositions.