Structured Lipid Particles for Stable Submicron Retinol Encapsulation
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Solution Overview
Problem
Existing encapsulation methods for hydrophobic compounds, such as retinol, fail to achieve sufficient stability over time, encapsulation efficiency, and skin penetration while maintaining a submicron particle size, and do not meet the growing demand for natural and environmentally friendly raw materials.
Innovation Solution
A method involving a specific ratio of wax to oil (1:2 to 1:15) and a combination of three surfactants (non-ionic, solid at room temperature, and phospholipid) is used to create a structured lipid particle suspension, resulting in spherical, homogeneous submicron particles with a waxy shell and oily core, which are stable at room temperature and protect the encapsulated active against degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If retinol is dissolved in oil to protect it from degradation, then the stability of retinol is improved, but the protection is insufficient and degradation still occurs over time
Solution Approach 1:
The patent applies nested encapsulation by placing retinol molecules inside a lipid matrix, which is then enclosed within a protective shell formed by surfactants and co-lipids. This multi-layer nested structure provides progressive protection: the lipid matrix prevents direct contact with degrading environmental factors, while the outer shell maintains structural integrity and controls release, thereby extending protection duration significantly beyond simple oil dissolution
Solution Approach 2:
The patent creates composite lipid particles combining multiple materials with complementary functions: solid lipids provide structural framework, liquid lipids provide flexibility and solubility for retinol, surfactants provide surface stability and prevent aggregation, and co-lipids enhance membrane fluidity. This composite approach synergistically improves both immediate stability and long-term protection duration
2Reliability
If wax-based solid lipid nanoparticles are used to encapsulate retinol, then protection is improved, but particle size is large and skin penetration is limited
Solution Approach 1:
The patent fundamentally changes the physical-chemical parameters of the lipid particles by using a mixture of solid and liquid lipids instead of pure solid waxes. This parameter change lowers the melting point and increases fluidity of the particle matrix, enabling the formation of smaller submicron particles (100-1000 nm) that can penetrate skin barriers more effectively while maintaining adequate protection through the liquid crystal phase organization of the lipid mixture
3Reliability
If solid and liquid lipids are mixed to create SLC particles, then retinol protection is improved, but particle size reduction to submicron level is insufficient for optimal skin penetration
Solution Approach 1:
The patent introduces surfactants and co-lipids as intermediary substances that mediate between the lipid matrix and the aqueous environment. These intermediaries reduce surface tension, prevent lipid aggregation, and stabilize the emulsion during homogenization, enabling the formation of uniform submicron particles with sizes optimized for skin penetration while maintaining the protective lipid matrix structure
4Object-generated harmful factors
If retinol is encapsulated to improve stability, then degradation is reduced, but encapsulation efficiency and stability over time remain insufficient
Solution Approach 1:
The patent applies local quality by creating distinct functional zones within the particle structure: the inner lipid matrix provides a hydrophobic environment matching retinol's polarity for high encapsulation efficiency, the intermediate layer provides structural stability, and the outer surfactant shell provides colloidal stability in aqueous media. Each zone is optimized with specific material properties to fulfill its local function, achieving overall high encapsulation efficiency and long-term 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 method achieves encapsulation rates of at least 70% with stability over one year, maintains active content without significant degradation, and facilitates slow release and penetration into the skin, using environmentally friendly materials.
Implementation Method 1
The mixture further comprises one or more surfactants
Implementation Method 2
a step of hot forming of an emulsion of said mixture
Implementation Method 3
a cooling step to form said suspension of structured particles
Data Source
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AI summary
A mixture is formed comprising an aqueous phase, a waxy phase, and an oily phase containing at least one hydrophobic compound, such as retinol, and a system of three surfactants, a hot emulsion of said mixture is thereafter formed, then a reduction in the size of the particles of said emulsion to substantially a submicron size is carried out, and finally according to a cooling is performed to form at room temperature a suspension of structured particles. An aqueous suspension of lipid particles structured substantially into a waxy shell and an oily core encapsulating the compound is obtained, having a satisfactory encapsulation rate and improved long-term stability, for use in particular in the cosmetics industry.