Antimicrobial Microcapsules with Immobilized Silver

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing perfumery delivery systems face challenges in maintaining long-lasting antimicrobial activity and controlled fragrance release due to the volatility of odoriferous compounds and inefficiencies in incorporating silver nanoparticles into microcapsules, leading to the presence of free silver particles and complex process steps.

Innovation Solution

A process for preparing antimicrobial polyurea-based core-shell microcapsules involves in-situ nucleation and growth of silver particles during interfacial polymerization in the presence of an anionic emulsifier, where a silver salt is added followed by a reducing agent, forming microcapsules with silver particles immobilized on or in the shell, thereby reducing free silver particles and optimizing loading.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If silver nanoparticles are incorporated into microcapsules using pre-made solutions, then antimicrobial activity is achieved, but free silver particles remain in solution and the process becomes complex

Engineering Contradiction:

Improveantimicrobial activityVSAvoidprocess steps

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the microcapsule formation process with in-situ silver nanoparticle synthesis into a single integrated process. The silver nanoparticles are generated directly within the microcapsule shell during interfacial polymerization, eliminating the need for separate nanoparticle preparation and incorporation steps, thus reducing process complexity while maintaining antimicrobial activity

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent uses a reducing agent as an intermediary substance that facilitates the conversion of silver ions to silver nanoparticles directly within the microcapsule shell. This intermediary enables controlled nanoparticle formation in-situ, preventing free particles in solution while ensuring reliable antimicrobial functionality

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If silver nanoparticles are loaded into microcapsules, then antimicrobial effect is enhanced, but control of nanoparticle size and loading optimization are difficult

Engineering Contradiction:

Improveantimicrobial effectVSAvoidnanoparticle size control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent employs a self-regulating mechanism where the interfacial polymerization process automatically controls the nucleation and growth of silver nanoparticles. The polymerization conditions and reducing agent concentration self-regulate the nanoparticle size and distribution, achieving precise control without requiring complex external intervention or optimization steps

Inventive Principle:

Principle #25Self-service

3Ease of operation

If odoriferous compounds are released for perfuming effect, then fragrance delivery is achieved, but volatility causes rapid loss of olfactive benefit

Engineering Contradiction:

Improvefragrance deliveryVSAvoidolfactive benefit duration

Core Design Contradiction:

Ease of operationVSDuration of action of moving object

Solution Approach 1:

The patent uses a polyurea-based microcapsule shell that acts as a flexible barrier to control the release of encapsulated fragrance compounds. The shell structure provides controlled permeability, allowing gradual release of odoriferous compounds while preventing their rapid volatilization, thus extending the duration of olfactive benefit while maintaining effective fragrance delivery

Inventive Principle:

Principle #30Flexible shells and thin films

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 approach results in microcapsules that provide a long-lasting antimicrobial effect and controlled fragrance release, enhancing the loading of silver nanoparticles and reducing the presence of free silver particles, while maintaining the stability and effectiveness of the antimicrobial and perfuming properties.

Implementation Method 1

adding a polyamine, a silver salt and a reducing agent provided that the reducing agent is added after the silver salt; to form microcapsules with polyurea-based walls comprising silver particles in or on the walls

Methodology Applied

Scientific EffectReduction: Reduction

Implementation Method 2

dispersing the oil phase into an aqueous solution comprising an anionic emulsifier to form an oil-in-water emulsion

Methodology Applied

Scientific EffectEmulsion: Emulsion

Implementation Method 3

Polyurea capsules, formed by interfacial polymerisation between a polyisocyanate and a polyamine

Methodology Applied

Scientific EffectInterfacial polymerization: Chemical Bonding

Data Source

PatentEP3160635B1Process for preparing antimicrobial microcapsules

Publication Date: 2021.03.03 FIRMENICH SA

AI summary

More particularly, the present invention relates to a process for producing antimicrobial core-shell microcapsules with immobilized silver particles into and onto the shell. The latter can be used in home or personal care products for delivering a perfuming and malodour-countering effect. The microcapsules obtainable by such a process and the consumer products comprising these microcapsules are also objects of the invention.