Dual-Layer Coated Nanoparticles for Sunscreen Stability

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Solution Overview

Problem

Conventional coatings for particles, such as silicones and fluorocarbon polymers, are unsuitable for particle encapsulation using spraying/drying techniques and can adversely affect the stability of sunscreen compositions due to the release of free oxygen radicals by nanoparticles like titanium dioxide and zinc oxide, which also tend to settle into skin wrinkles.

Innovation Solution

A dual-layer coating comprising a meta-stable catholyte inner layer and a hydrophobic polymer outer layer with branched moieties, where the hydrophobic polymer anchors the inner layer onto the surface of core particles, such as zinc oxide nanoparticles, preventing them from reacting with surroundings and neutralizing free oxygen radicals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If nanoparticles like titanium dioxide and zinc oxide are used in sunscreen compositions, then sun protection effectiveness is improved, but free oxygen radicals are released which adversely affect the stability of the composition

Engineering Contradiction:

Improvesun protection effectivenessVSAvoidfree oxygen radicals release

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The coating is divided into two distinct layers: an inner layer comprising metal oxide nanoparticles (titanium dioxide or zinc oxide) for UV protection, and an outer layer comprising a hydrophobic polymer for stability. This segmentation isolates the harmful radical-generating nanoparticles from the surrounding environment while maintaining their protective function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The hydrophobic polymer outer layer acts as an intermediary barrier between the metal oxide nanoparticles and the sunscreen composition matrix. This intermediate layer prevents direct interaction that would otherwise generate free oxygen radicals, thereby stabilizing the composition while preserving UV protection.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If nanoparticles like titanium dioxide and zinc oxide are used in sunscreen compositions, then sun protection effectiveness is improved, but the nanoparticles tend to settle into skin wrinkles

Engineering Contradiction:

Improvesun protection effectivenessVSAvoidparticle settling into wrinkles

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The hydrophobic polymer outer layer forms a flexible thin film coating around the metal oxide nanoparticles. This flexible shell modifies the surface properties of the nanoparticles, improving their compatibility with skin and preventing them from settling into wrinkles while maintaining their UV protective function.

Inventive Principle:

Principle #30Flexible shells and thin films

3Stability of the object's composition

If conventional coatings such as silicones are used on particles, then compatibility with oils and stability in emulsion systems are improved, but they are unsuitable for particle encapsulation using spraying/drying techniques

Engineering Contradiction:

Improveemulsion system stabilityVSAvoidspraying/drying encapsulation suitability

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The invention changes the key parameter of the coating material from conventional silicones to hydrophobic polymers with specific properties (low glass transition temperature, appropriate molecular weight). This parameter change enables the coating to be compatible with spraying/drying encapsulation techniques while maintaining emulsion system stability.

Inventive Principle:

Principle #35Parameter changes

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 dual-layer coating stabilizes nanoparticles, preventing them from settling into skin wrinkles and reducing oxidative damage, allowing their safe incorporation into sunscreen compositions without affecting stability.

Implementation Method 1

The hydrophobic polymer with branched moieties to wrap around the particle to prevent the meta-stable substance from reacting with its surroundings

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

Method of using sonochemical activaction to form meta-stable substances

Methodology Applied

Scientific EffectSonochemical activation: Sonochemistry

Data Source

PatentUS10105299B2Method of using sonochemical activaction to form meta-stable substances

Publication Date: 2018.10.23 THE RES FOUNDATION FOR THE STATE UNIV OF NEW YORK

AI summary

A method for forming a coated particle having a core particle that is fully coated by a dual-layer coating that includes an inner layer formed of a hydrophilic composition and an outer layer formed of a hydrophobic polymer. The core particles are added to a hydrophilic solution and mixed together. The hydrophobic polymer is then added to form a mixture. The mixture is sonicated to coat the particles and the coated particles are separated and dried to form meta-stable coated particles.