Amide-Bonded Semiconductor Nanoparticle Assembly Prevents Quenching

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Solution Overview

Problem

Current semiconductor nanoparticles with core/shell structures face luminance degradation and concentration quenching when accumulated in a highly concentrated state, limiting their effectiveness as fluorescent diagnostic agents.

Innovation Solution

The semiconductor nanoparticles are bonded using amide bonding, specifically through reacting amino-terminated and carboxyl-terminated core/shell nanoparticles, maintaining appropriate gaps and preventing concentration quenching, with materials like InP, CdSe, and CdTe used for the core and suitable inorganic semiconductors for the shell.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If semiconductor nanoparticles are assembled in a highly concentrated state to increase luminance, then the luminance per particle increases, but concentration quenching occurs due to electron transfer between contacting particles

Engineering Contradiction:
Improveluminance per particleVSAvoidconcentration quenching
Core Design Contradiction:
Illumination intensityVSLoss of energy

Solution Approach 1:

The patent introduces a specific ligand structure (Formula 1) as an intermediary between semiconductor nanoparticles. This ligand contains a chelating group that binds to metal atoms on the particle surface and a spacer group that maintains appropriate spacing. The intermediary prevents direct contact between particles, thereby eliminating electron transfer and concentration quenching while allowing high concentration assembly for increased luminance.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the ligand parameters by specifying particular structural features (chelating group type, spacer length, molecular weight range of 50-500 Da). By changing these ligand parameters, the patent optimizes the balance between maintaining particle separation (preventing quenching) and enabling high concentration assembly (increasing luminance).

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If semiconductor nanoparticles are synthesized in aqueous or non-aqueous solution, then the synthesis process is simplified, but the particles degrade in light emitting properties due to aggregation or moisture exposure

Engineering Contradiction:
Improvesynthesis processVSAvoidlight emitting stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent employs a composite ligand structure combining organic chelating groups with inorganic metal atom coordination. This composite approach creates a stable surface layer that protects the semiconductor core from aggregation and moisture while maintaining the simplicity of solution-phase synthesis. The chelating group forms strong coordinate bonds with surface metal atoms, creating a protective composite interface.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The chelating group ligand creates an inert protective environment around the semiconductor nanoparticle surface. This ligand shell acts as a barrier that prevents moisture and oxygen from reaching the particle surface, thereby preventing degradation while allowing the particles to be synthesized and handled in conventional solution environments.

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

3Duration of action of stationary object

If semiconductor nanoparticles are dispersed and fixed in a matrix such as transparent glass, then the high luminance properties are maintained for a long period, but the nanoparticles cannot be accumulated so much in respect of concentration

Engineering Contradiction:
Improveluminance stability over timeVSAvoidnanoparticle concentration
Core Design Contradiction:
Duration of action of stationary objectVSQuantity of substance

Solution Approach 1:

The patent extracts the stabilization function from the solid glass matrix and transfers it to the soluble ligand molecules. By taking out the stabilizing role from the rigid glass environment and implementing it through flexible ligand chemistry, the patent enables both high concentration particle assembly and long-term stability without requiring embedding in a matrix.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the stabilization mechanism from physical confinement in a solid matrix to chemical coordination through ligand binding. By modifying the stabilization approach from mechanical (matrix embedding) to chemical (ligand coordination), the patent achieves both high particle concentration and long-term luminance stability in solution.

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

This approach maintains high luminance without concentration quenching even at high concentrations, enhancing the stability and application potential of semiconductor nanoparticle assemblies as fluorescent labeling agents.

Implementation Method 1

the semiconductor particles are bonded with each other by amide bonding

Methodology Applied
Scientific EffectAmide bonding: Chemical Bonding

Implementation Method 2

semiconductor nanoparticles that emit fluorescence as a fluorescent labeling agent

Methodology Applied
Scientific EffectFluorescence: Fluorescence

Implementation Method 3

By using a semiconductor material having a larger band gap than core particles as a shell, a quantum well is formed to produce a quantum confinement effect, significantly increasing luminance

Methodology Applied
Scientific EffectQuantum confinement effect:

Data Source

PatentUS8901535B2Semiconductor nanoparticle assembly
Publication Date: 2014.12.02 KONICA MINOLTA INC

AI summary

A semiconductor nanoparticle assembly including semiconductor nanoparticles having a core/shell structure, and wherein the semiconductor nanoparticles are bonded by means of amide bonds.