Silk Fibroin Extraction Using Basic Ionic Liquids

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Solution Overview

Problem

The existing methods for extracting silk from Bombyx mori cocoons face challenges such as the short half-life of silk solutions, degradation of proteins during processing, and the use of expensive and toxic solvents, which limits the prolonged use of silk for biomedical applications.

Innovation Solution

The use of basic ionic liquids, specifically tetrabutylphosphonium hydroxide and choline hydroxide, to regenerate silk fibroin under mild conditions, allowing for efficient extraction and preservation of silk properties without generating waste, and enabling the recovery and reuse of the ionic liquids.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If inorganic salt solutions or concentrated acid solutions are used to dissolve fibroin, then the fibroin can be disrupted and dissolved, but protein degradation occurs during the process

Engineering Contradiction:

Improvefibroin structural integrityVSAvoidprotein degradation

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical parameters of the dissolution medium by using basic ionic liquids (choline hydroxide and tetrabutylphosphonium hydroxide) instead of traditional inorganic salts or concentrated acids. These ionic liquids provide a basic environment that disrupts hydrogen bonding in fibroin without causing protein degradation, thus resolving the contradiction between effective dissolution and protein stability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs ionic liquids that can be easily removed and regenerated for repeated use. The ionic liquids are evaporated off after silk dissolution, and the same ionic liquid can be reused multiple times, eliminating the need for expensive, toxic solvents while maintaining protein integrity throughout the process

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Stability of the object's composition

If formic acid solution or phosphoric acid solution is used to disrupt peptide bonds, then dissolution is achieved, but peptide bond disruption and protein denaturation occur

Engineering Contradiction:

Improveprotein structureVSAvoidpeptide bond integrity

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

Instead of using acidic solutions (formic acid, phosphoric acid) that disrupt peptide bonds and denature proteins, the patent inverts the approach by using basic ionic liquids. These basic ionic liquids achieve fibroin dissolution through hydroxide ions that disrupt hydrogen bonding without breaking peptide bonds or denaturing proteins, thus maintaining both structural integrity and reliability

Inventive Principle:

Principle #13The other way round (Inversion)

3Duration of action of moving object

If HFIP, HFA, or TFA is used to reconstitute silk solution, then prolonged use is enabled, but the solvents are expensive, toxic and strongly corrosive

Engineering Contradiction:

Improvesilk solution half-lifeVSAvoidsolvent toxicity and cost

Core Design Contradiction:

Duration of action of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent replaces expensive, toxic solvents (HFIP, HFA, TFA) with inexpensive, non-toxic basic ionic liquids (choline hydroxide and tetrabutylphosphonium hydroxide). The ionic liquids can be easily evaporated and regenerated for repeated use, enabling prolonged silk solution stability without the harmful effects of fluorinated solvents

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The basic ionic liquids serve as an intermediary medium that enables silk fibroin dissolution and maintains solution stability. The ionic liquids mediate between the fibroin structure and the desired prolonged solution stability, providing a safe, renewable platform that avoids direct contact with toxic solvents

Inventive Principle:

Principle #24Intermediary (Mediator)

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 method provides a cost-effective, time-efficient, and eco-friendly process for regenerating silk fibroin, maintaining its structural integrity and allowing for prolonged use in biomaterial fabrication, with the ionic liquids being environmentally friendly and reusable.

Implementation Method 1

aqueous inorganic salt solutions and concentrated acid solutions are usually used because of their ability to disrupt hydrogen bonding

Methodology Applied

Scientific EffectHydrogen bonding disruption:

Implementation Method 2

The silk regenerated after treatment with these ionic liquids exhibit almost similar properties to the native silk fibroin

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS11512109B2Method for extraction of powdered silk fibroin from <i>bombyx mori </i>cocoons using aqueous solution of basic ionic liquid

Publication Date: 2022.11.29 COMSATS UNIV ISLAMABAD

AI summary

A method is provided for extraction of fine silk fibroin powder from Bombyx mori silk cocoons. The conventional method of silk processing includes dissolution of the degummed silk fibers in some strong salt solutions followed by a dialysis step. The earlier reported strong salt solutions have either associated environment issues or lower dissolution ability for silk. However, the provided method includes degumming silk cocoons, drying and cutting the degummed silk fibers, mixing the fibers with an ionic liquid, stirring the mixture, regeneration of silk from the mixture with the help of an anti-solvent followed by centrifugation, drying the precipitated silk and finally obtaining a fine powder of silk.