Chitosan-PEG Interpolymer Thermoreversible Gelation for Drug Delivery
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Solution Overview
Problem
There is a need for biodegradable drug delivery compositions that exist as a liquid below the body temperature and gel at body temperature, which are compatible with living tissue and can release drugs over an extended period, as existing compositions often have acidic pH and harmful components.
Innovation Solution
The development of an interpolymer of chitosan and polyethylene glycol that is a liquid below 25°C and gels above 35°C, allowing for the incorporation and controlled release of drugs, with optional covalent cross-linking to adjust degradation rates, ensuring biocompatibility and effective drug delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If chitosan solution is prepared in dilute acid to dissolve chitosan, then chitosan solubility is improved, but pH becomes acidic which is irritating to living tissue
Solution Approach 1:
The invention extracts and removes the harmful acidic component (dilute acid) from the chitosan preparation process by using alternative solvents such as dilute base or water-soluble organic solvents, thereby maintaining chitosan solubility while eliminating tissue irritation
Solution Approach 2:
The invention introduces intermediary substances (alternative solvents like dilute base or water-soluble organic solvents) that mediate between chitosan and the final application environment, enabling chitosan dissolution without requiring acidic conditions that harm living tissue
2Stability of the object's composition
If excess sodium glycerol phosphate salt is added to gel chitosan solution, then gelation is achieved, but the salt may be harmful if absorbed by living tissue
Solution Approach 1:
The invention extracts and removes the harmful excess salt component from the gelation process by using alternative gelation mechanisms such as ionic crosslinking with safe counterions or physical gelation, thereby achieving gelation without requiring harmful concentrations of sodium glycerol phosphate
Solution Approach 2:
The invention introduces intermediary gelation mechanisms (ionic crosslinking with biocompatible ions or physical gelation through temperature or pH changes) that mediate between chitosan molecules to form gels without requiring harmful concentrations of sodium glycerol phosphate salt
3Productivity
If synthetic polymers are used for thermoreversible drug delivery, then drug delivery functionality is achieved, but biocompatibility and biodegradability are reduced
Solution Approach 1:
The invention creates composite material systems using natural polymers (chitosan) combined with safe inorganic salts or crosslinking agents, achieving thermoreversible gelation and drug delivery functionality while maintaining the biocompatibility and biodegradability characteristics of natural materials
Solution Approach 2:
The invention utilizes parameter changes (temperature, pH, ionic strength) to control the gelation and drug release behavior of natural polymer-based compositions, enabling thermoreversible drug delivery functionality without relying on synthetic polymers
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 chitosan-polyethylene glycol interpolymer compositions are biodegradable, compatible with living tissue, and can deliver drugs effectively over time, promoting bone growth and treating conditions like osteoporosis by releasing growth factors and other therapeutic agents in a controlled manner.
Implementation Method 1
the interpolymer is a liquid below 25° C. and a gel above 35° C.
Implementation Method 2
the compositions can be degraded by living tissue (i.e., are biodegradable)
Data Source
AI summary
The present invention provides compositions comprising an interpolymer of chitosan and polyethylene glycol, wherein the interpolymer is a liquid below 25° C. and a gel above 35° C. The present invention also provides methods for using the compositions to deliver drugs to a living body over time.