Ligand-Capped Platinum Nanoparticles for Biocompatible PHIP
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Solution Overview
Problem
Existing hyperpolarization techniques using homogeneous catalysts face biotoxicity concerns and polarization decay during separation, while heterogeneous catalysts in non-biocompatible solvents yield low polarization and suffer from leaching issues.
Innovation Solution
Development of cysteine-capped platinum nanoparticles as a heterogeneous catalyst that is water-soluble, allowing high substrate polarization via PHIP, with the ability to be immobilized or filtered, ensuring biocompatibility and effective separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If homogeneous catalysts are used for PHIP hyperpolarization, then high nuclear spin polarization can be achieved, but biotoxicity concerns arise due to inability to separate the catalyst from solution
Solution Approach 1:
The patent uses ligands as intermediary molecules that bind to the catalyst surface, creating a protective layer that enables both high catalytic activity and easy separation. The ligand-capped nanoparticles serve as an intermediary between the homogeneous catalyst (providing high polarization) and the requirement for separation (reducing toxicity), allowing the catalyst to function effectively while being removable via filtration or centrifugation
Solution Approach 2:
The patent changes the physical state of the catalyst from dissolved (homogeneous) to particulate (heterogeneous) by forming nanoparticles. This parameter change in the catalyst's physical form maintains the chemical activity needed for high polarization while enabling separation through filtration or centrifugation, thereby reducing biotoxicity concerns
2Object-affected harmful factors
If phase separation technique is used to separate catalyst from solution, then catalyst can be removed, but polarization decays during extraction process
Solution Approach 1:
The patent extracts the catalyst from the solution in a controlled manner by forming discrete nanoparticulate entities that can be easily removed via filtration or centrifugation. The ligand capping ensures the catalyst particles remain stable and do not aggregate, allowing for rapid separation that minimizes polarization decay during the extraction process
3Ease of operation
If heterogeneous catalysts are used in non-biocompatible solvents, then catalyst separation is easier, but polarization yield is low and leaching problems occur
Solution Approach 1:
The patent creates composite material structures by combining metal nanoparticles with organic ligand shells. This composite structure provides the benefits of heterogeneous catalysts (easy separation) while the ligand shell maintains biocompatibility and prevents leaching, thereby achieving both high polarization yield and ease of separation in water-soluble systems
Solution Approach 2:
The patent applies different properties to different parts of the catalyst system: the metal core provides catalytic activity for high polarization, while the ligand shell provides water solubility and prevents leaching. This local differentiation of properties allows the catalyst to achieve high polarization yield while maintaining ease of separation and biocompatibility
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 nanoparticles achieve high nuclear-spin polarization in biocompatible conditions, enabling efficient separation and recyclability, making them suitable for in vivo medical imaging applications.
Implementation Method 1
Hyperpolarization techniques include spin exchange optical pumping, the more established technique of dynamic nuclear polarization (DNP), and the use of para-hydrogen induced polarization (PHIP) or Signal Amplification by Reversible Exchange (SABRE). The nearly pure stable singlet spin state of para-hydrogen can subsequently be utilized to hyperpolarize a molecule of interest by an addition reaction or by a catalyst-mediated, reversible exchange process.
Implementation Method 2
cysteine-capped platinum nanoparticles serve as a heterogeneous catalyst which yields large polarization by PHIP in water
Data Source
AI summary
A heterogeneous catalyst composition for para-hydrogen induced polarization includes ligand-capped nanoparticles dispersed in water. The ligand-capped nanoparticles include metal nanoparticles that are surface functionalized with organic ligands, a molecular weight of the organic ligands is no greater than 300 g/mol, and the organic ligands each includes multiple binding moieties as coordinates sites for binding to a nanoparticle surface.