Core-shell nanoparticles with pH-responsive silica shells
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Solution Overview
Problem
The production of silica-based core-shell nanoparticles for bioanalytical applications, such as drug delivery and bioimaging, often requires non-ideal conditions like elevated temperatures and non-physiological pH values, and lacks efficient morphological and structural control.
Innovation Solution
The development of core-shell nanoparticles with a cationic polymer core and a silica shell, where the core is formed using diblock copolymers like poly[2-(diisopropylamino)ethyl methacrylate]-block-poly[2-(dimethylamino)ethyl methacrylate] (PDPA-PDMA), allowing for controlled silica deposition under mild conditions and pH-responsive properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods (Stöber chemistry or microemulsion) are used to synthesize silica-based core-shell nanoparticles, then silica shells can be formed on functional cores, but non-ideal conditions such as elevated temperatures, non-physiological pH values, and large amounts of surfactants and organic co-solvents are required
Solution Approach 1:
The invention changes the physical and chemical parameters of the synthesis process by using aqueous ammonia as a mild base catalyst instead of strong bases, maintaining physiological pH (6.5-7.5), and conducting the reaction at room temperature. This allows silica shell formation under biocompatible conditions while maintaining reliable coating on the copolymer core
Solution Approach 2:
The invention replaces expensive and harmful organic co-solvents and large amounts of surfactants with simple, inexpensive, and environmentally benign aqueous ammonia and water, eliminating the need for extensive purification steps and reducing waste
2Manufacturing precision
If conventional silica coating methods are used, then silica shells can be deposited on cores, but morphological and structural control remains challenging and requires complex procedures
Solution Approach 1:
The invention uses amphiphilic block copolymers that self-assemble into micelles with well-defined core-shell structures before silica deposition. This preliminary self-organization provides a pre-formed template with controlled morphology that directs the subsequent silica coating process, eliminating the need for complex external structuring procedures
Solution Approach 2:
The block copolymer micelles spontaneously organize into structured assemblies with hydrophobic cores and hydrophilic coronas in aqueous solution, creating their own templates for silica deposition without requiring external guidance. The system self-assembles and self-templates, simplifying the overall synthesis procedure while maintaining precise morphological control
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 enables the formation of well-defined nanoparticles with controlled size and morphology, maintaining colloidal stability and facilitating pH-triggered release of active agents, while avoiding harsh synthesis conditions.
Implementation Method 1
block copolymers can self-assemble into a wide range of nanostructures that can be used for controlling the formation of various inorganic materials
Implementation Method 2
coating functional cores with silica shells either by using Stöber chemistry or by means of a microemulsion approach
Implementation Method 3
biomineralisation of silica, or biosilicification, occurs in water under ambient conditions for various biological systems
Data Source
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AI summary
The invention provides a composition comprising core-shell nanoparticles, the nanoparticles comprising (a) cationic core material comprising polymer; and (b) a shell material comprising silica. Preferred core materials comprise diblock copolymer micelles comprising one block of dialkylaminoethyl methacrylate units which are partially or fully quaternised and one block of dialkylaminoethyl methacrylate units that remain non-quaternised . The invention also provides a method for the preparation of the said composition, the method involving (a) preparing a cationic core material comprising polymer; and (b) coating the core material with a shell comprising silica by treating the polymer with a silica precursor under ambient conditions. The invention also envisages a composition comprising core-shell nanoparticles which is adapted to facilitate controlled delivery of at least one active agent into a system in response to controlled changes in the pH of the system.