Redox-Modified Chitosan Shells for Biodegradable Controlled Release
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Solution Overview
Problem
Existing microencapsulation technologies face challenges in achieving biodegradability, structural integrity, and compatibility with harsh environments, particularly in aqueous surfactant-based compositions, while ensuring controlled release of encapsulated actives.
Innovation Solution
The development of core-shell delivery particles using a shell composed of a reaction product of a cross-linking agent and redox-initiator-modified chitosan, which is treated with acids to achieve a specific molecular weight and reduced viscosity, allowing for enhanced biodegradability and compatibility with matrices like laundry formulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If biodegradable materials are used to form delivery particles via coacervation, spray-drying or phase inversion precipitation, then biodegradability is improved, but the particles become highly porous and cause premature release of the benefit agent
Solution Approach 1:
The invention uses a composite shell structure comprising chitosan (a biodegradable polysaccharide) crosslinked with a crosslinking agent. This composite approach maintains biodegradability through the chitosan component while the crosslinked network provides structural integrity and reduces porosity, preventing premature release of the encapsulated benefit agent.
Solution Approach 2:
The invention modifies the physical and chemical parameters of the shell material by controlling the crosslinking degree and using redox-initiator-modified chitosan with specific molecular weight ranges (1-600 kDal). These parameter changes optimize the balance between biodegradability and particle stability, allowing the particles to maintain integrity while remaining biodegradable.
2Duration of action of moving object
If mechanical rupture is used as the release mechanism, then controlled release at specific time is improved, but rupture may occur at undesired times when capsules are subject to mechanical stress
Solution Approach 1:
The invention employs a flexible yet resilient shell made of crosslinked chitosan that can withstand mechanical stress without rupturing prematurely. The shell's flexibility allows it to deform under stress while maintaining integrity, and it returns to its original state, preventing unwanted release while still allowing controlled release at the desired time.
Solution Approach 2:
The spherical geometry of the delivery particles distributes mechanical stress uniformly across the shell surface, preventing localized stress concentration that could cause premature rupture. This spherical shape enhances the particle's ability to withstand mechanical stress while maintaining controlled release characteristics.
3Strength
If non-leaky delivery particles with chemical cross-linking are used, then structural integrity is improved, but biodegradability is lost
Solution Approach 1:
The invention uses redox-initiator-modified chitosan with controlled molecular weight (1-600 kDal) and optimizes the crosslinking degree to achieve the right balance. The crosslinking provides sufficient shell integrity to prevent leakage, while the moderate crosslinking density and biodegradable crosslinking agents maintain the particle's ability to degrade over time.
Solution Approach 2:
The invention employs biodegradable crosslinking agents that allow the shell to fulfill its protective function temporarily and then degrade naturally. This approach creates a temporary but reliable structure that provides integrity during use and then breaks down, eliminating the need for permanent non-biodegradable crosslinks.
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
The particles exhibit improved structural integrity, reduced leakage, and compatibility with harsh environments, degrading at least 40% in 60 days and maintaining stability in matrices, while ensuring controlled release of the core material.
Implementation Method 1
The chitosan is a modified chitosan wherein the chitosan is treated with a redox initiator under acid conditions
Implementation Method 2
the chitosan is treated with a redox initiator under acid conditions, leading to unique properties in the polymeric material
Implementation Method 3
the shell comprises a reaction product of a cross-linking agent and polysaccharide
Data Source
AI summary
A population of core-shell delivery particles comprising a benefit agent core material and a shell encapsulating the core material is described, along with a process for forming such delivery particles and articles of manufacture. The shell is the reaction product of a crosslinking agent and a modified chitosan. Chitosan is treated with a mixture of an acid and redox initiator comprising a persulfate or peroxide, which results in an enhanced polymeric shell. The delivery particle of the invention has improved release characteristics, with enhanced degradation characteristics in OECD test method 301B.