Photosensitive Capsule Shell Design for Controlled Release
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Solution Overview
Problem
Existing photosensitive capsules for cosmetic and pharmaceutical applications face issues with leaktightness during storage and efficient release of active agents, particularly when exposed to environmental changes such as pH, temperature, light, or ionic strength, leading to premature degradation or inefficient delivery of active agents.
Innovation Solution
Development of core/shell type capsules with a shell comprising alternating layers of a photosensitive anionic polymer and a cationic polymer, which provides leaktightness during storage and controlled release of active agents upon exposure to light, allowing for prolonged release over 1 to 5 days.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hollow polymer particles are used for encapsulating active agents, then the active agents can be protected from environmental degradation, but the capsules show poor leaktightness during storage and active agents escape prematurely
Solution Approach 1:
The capsule shell is segmented into multiple alternating layers of anionic and cationic polymers, creating a multilayer structure that provides superior leaktightness compared to single-layer capsules. This segmentation allows each layer to contribute to the overall barrier function, preventing active agent escape during storage.
Solution Approach 2:
The capsule shell is formed from composite materials consisting of alternating anionic and cationic polymer layers. This composite structure leverages the complementary properties of oppositely charged polymers to create a stable, leaktight barrier that maintains encapsulation integrity during storage.
2Productivity
If photosensitive capsules are designed for controlled release upon light exposure, then efficient delivery of active agents can be achieved, but the capsules may release active agents prematurely when exposed to environmental light during storage
Solution Approach 1:
The photosensitive polymer layers are positioned specifically within the multilayer shell structure, creating local photosensitive zones that can be activated by light. This localized photosensitivity allows controlled release when needed while maintaining overall shell integrity and stability during storage in the dark.
Solution Approach 2:
The capsule shell transitions from a static, stable structure during storage to a dynamic, responsive structure upon light exposure. The photosensitive polymer layers remain stable in the dark but undergo conformational changes or become permeable when irradiated, enabling controlled release of active agents on demand.
3Speed
If the capsule shell is made highly permeable to allow rapid release of active agents, then efficient delivery can be achieved, but the capsules lose leaktightness and active agents escape during storage
Solution Approach 1:
The capsule shell exhibits dynamic permeability that changes based on light exposure. In the dark, the shell maintains low permeability for leaktightness; upon light irradiation, the photosensitive layers become highly permeable, enabling rapid release of active agents when needed.
Solution Approach 2:
The permeability parameter of the capsule shell is changed by light exposure. The photosensitive polymer layers transition from a low-permeability state during storage to a high-permeability state upon irradiation, controlling the release speed of active agents without compromising storage stability.
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 capsules ensure effective leaktightness during storage and controlled, prolonged release of active agents when applied to keratin materials and exposed to light, enhancing the stability and efficacy of cosmetic and pharmaceutical products.
Implementation Method 1
The first polymer is a photosensitive anionic polymer... When the capsules are deposited on keratin materials and then irradiated with natural or artificial light, the first photosensitive polymer changes conformation, modifying the leaktightness of the shell and giving rise to leakage of the active agent from the capsule.
Data Source
AI summary
The invention relates to capsules of core/shell type, the core comprising an active agent; the shell comprising one or more concentric and alternating layers of a first photosensitive anionic amino polymer and of a second cationic polymer. The invention also relates to a cosmetic or pharmaceutical composition comprising such capsules. The invention also relates to a non-therapeutic cosmetic process for treating keratin materials, comprising the application to the keratin materials of a cosmetic composition comprising the said capsules, followed by exposure of the deposit formed on the keratin materials to natural light or to artificial light with a wavelength of between 360 and 600 nm.