Gold Nanoparticle Synthesis in Protein Cages
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Solution Overview
Problem
Existing methods for synthesizing gold nanoparticles often require extreme conditions and additional modification steps, and struggle to uniformly generate gold nanoparticles inside protein cages without altering the protein structure.
Innovation Solution
A two-step reduction strategy is employed, where gold ions are first trapped inside a protein cavity and then reduced with a strong reductant to form a nanocluster seed, followed by a second reduction with a weak reductant to grow the gold nanoparticle, allowing for controlled size and shape within the protein cage without modifying the protein.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If chemical methods are used to synthesize gold nanoparticles, then gold nanoparticles can be produced, but extreme conditions such as high temperature, elevated pressure, organic solvents, caustic pH and strong reducing reagents are required
Solution Approach 1:
The patent uses citrate as an intermediary substance that serves dual functions: it acts as a mild reducing agent to convert gold ions to gold nanoparticles, and as a stabilizing agent to prevent aggregation. This intermediary enables the reaction to proceed under mild conditions without requiring extreme temperatures, pressures, or strong reducing reagents.
Solution Approach 2:
The patent changes the reaction parameters from extreme conditions to mild conditions by controlling pH, temperature, and reagent concentrations. Specifically, the reaction is conducted at near-neutral pH and room temperature or slightly elevated temperatures, fundamentally altering the reaction conditions from harsh to benign.
2Quantity of substance
If chemical methods are used to synthesize gold nanoparticles, then gold nanoparticles can be produced, but additional functionalization steps are required
Solution Approach 1:
The patent merges the reduction step and the functionalization step into a single simultaneous process. Citrate both reduces gold ions to form nanoparticles and coats the nanoparticle surface with functional groups, eliminating the need for separate functionalization steps and simplifying the overall manufacturing process.
Solution Approach 2:
The citrate molecule performs multiple functions automatically during the synthesis process: it reduces gold ions, stabilizes the growing nanoparticles, and provides surface functionality. This self-service approach eliminates the need for additional manual intervention or separate processing steps.
3Manufacturing precision
If gold ions are reduced inside protein cages, then homogeneous nanoparticles can be produced, but nanoparticle formation on the exterior of the protein must be avoided
Solution Approach 1:
The patent applies local quality by creating different chemical environments inside and outside the protein cage. The interior of the cage provides a confined space with specific chemical properties that favor nanoparticle formation, while the exterior remains in a different chemical environment that prevents nanoparticle formation, thus achieving spatially differentiated functionality.
Solution Approach 2:
The protein cage acts as an intermediary structure that selectively allows gold ions to enter its interior while preventing reduction on the exterior. The cage's structure and chemical properties mediate the reduction process to occur only within its confined interior space, preventing harmful exterior nanoparticle formation.
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 enables the rational prediction of gold nanoparticle size and shape, producing highly homogeneous nanoparticles within intact protein shells, suitable for various protein cages, and avoids nanoparticle formation on the exterior, ensuring particles are encapsulated and stable.
Implementation Method 1
contacting the protein-encapsulated gold ion with a first reductant to reduce the gold ion and form a gold nanocluster seed in the inner cavity of the protein
Implementation Method 2
contacting the gold nanocluster seed in the inner cavity of the protein with a second reductant to mineralize and grow the gold nanoparticle
Data Source
AI summary
The present invention is directed to a method for fabricating a gold nanoparticle, the method comprising the steps of contacting a gold ion with a protein, wherein the protein has an inner cavity that can accommodate the gold ion, separating the protein with the encapsulated gold ion(s) from non-encapsulated gold ions, contacting the protein-encapsulated gold ion with a first reductant to reduce the gold ion and form a gold nanocluster seed in the inner cavity of the protein, wherein the first reductant is a strong reductant, and contacting the gold nanocluster seed in the inner cavity of the protein with a second reductant to mineralize and grow the gold nanoparticle.