Astatine-211 Solution Purification Using Reducing Agents

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Solution Overview

Problem

Conventional methods for producing astatine-211 solutions result in low radiochemical purity, leading to weak accumulation of radioactivity in the thyroid gland during in vivo experiments, limiting their effectiveness in radiotherapy.

Innovation Solution

A production method involving the addition of a reducing agent, such as ascorbic acid, to astatine-211 solutions to enhance radiochemical purity, resulting in improved accumulation of radioactivity in the thyroid gland.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional methods are used to produce astatine-211 solutions, then the production process is simple, but the radiochemical purity is low

Engineering Contradiction:
Improveradiochemical purityVSAvoidproduction process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent introduces a reducing agent as an intermediary substance that mediates between the astatine-211 and impurities. The reducing agent selectively reduces impurities while leaving astatine-211 unchanged, thereby purifying the solution without requiring complex separation equipment or multi-step processes.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the chemical parameter of the solution by adding a reducing agent, which alters the oxidation state of impurities. This parameter change enables selective reduction of impurities to a different chemical form that can be easily separated, thereby improving radiochemical purity through a relatively simple process modification.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If astatine-211 solutions with low radiochemical purity are used, then the production method is simple, but the accumulation of radioactivity in the thyroid gland is weak

Engineering Contradiction:
Improveaccumulation of radioactivity in thyroid glandVSAvoidradiochemical purity
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The reducing agent acts as a mediator that selectively interacts with impurities, converting them into forms that do not accumulate in the thyroid gland. This ensures that only the astatine-211 accumulates in the thyroid, improving both reliability and purity simultaneously.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful effect of impurities (which cause non-specific accumulation) into a beneficial separation process. By using the reducing agent, impurities are transformed into substances that can be easily removed, turning the problem of impurity presence into an opportunity for selective purification.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If astatine-211 solutions with low radiochemical purity are used, then the production cost is low, but the effectiveness of radiotherapy is limited

Engineering Contradiction:
Improveeffectiveness of radiotherapyVSAvoidradiochemical purity
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The reducing agent serves as a cost-effective intermediary that enables purification without requiring expensive complex equipment or multi-step processes. This allows production of high-purity astatine-211 solutions at reasonable costs, improving radiotherapy effectiveness while maintaining economic feasibility.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

By changing the chemical parameter of the solution through addition of a reducing agent, the patent achieves high radiochemical purity through a simple one-step process. This parameter change enables effective radiotherapy while avoiding the need for complex, expensive purification systems.

Inventive Principle:
Principle #35Parameter changes

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 method produces astatine-211 solutions with a radiochemical purity of not less than 50%, enhancing radioactivity accumulation in the thyroid gland and reducing non-specific accumulation in other organs, thereby improving the effectiveness of radiotherapy.

Implementation Method 1

a step of adding a reducing agent to an aqueous solution, ethanol solution, ethanol aqueous solution containing impurity derived from 211At

Methodology Applied
Scientific EffectReduction: Reduction

Data Source

PatentEP3733216B1Astatine solution and method for producing same
Publication Date: 2025.10.29 OSAKA UNIVERSITY
  • EP3733216B1 patent drawingFigure 1(a)~1(d)
  • EP3733216B1 patent drawingFigure 2~3
  • EP3733216B1 patent drawingFigure 4~5

AI summary

The present invention aims to provide an astatine solution that can be used in RI internal radiotherapy and the like for the treatment of thyroid gland disease and the like, and a production method thereof. The present invention provides a method for producing a solution containing 211At- (astatide ion) at a high radiochemical purity by using 211At obtained by a nuclear reaction as a starting material, including a step of adding a reducing agent to a solution containing an impurity derived from 211At; and a solution containing 211At- (astatide ion) at a radiochemical purity of not less than 30%.