Neutral Fluorescent Amide Markers for Membrane-Safe Mitochondria Imaging

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Solution Overview

Problem

Existing fluorescent dyes targeting mitochondria often change the mitochondrial membrane potential, leading to cell apoptosis due to their cationic nature, necessitating a neutral fluorescent marker with improved targeting ability and reduced cytotoxicity.

Innovation Solution

Development of a neutral fluorescent mitochondrial marker as an amide derivative, combining coumarin borate and Nile red borate derivatives with an amide compound to enhance mitochondria targeting and optical performance, synthesized through a reaction in a weakly basic organic solvent with a noble metal catalyst.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If cationic fluorescent dyes are used to target mitochondria, then mitochondria targeting ability is improved, but mitochondrial membrane potential changes and cell apoptosis occurs

Engineering Contradiction:

Improvemitochondria targeting abilityVSAvoidmitochondrial membrane potential change and cell apoptosis

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent inverts the conventional approach by using a neutral dye instead of a cationic dye. The neutral dye enters mitochondria through passive diffusion rather than active transport driven by membrane potential, thereby avoiding disruption of the mitochondrial membrane potential while still achieving mitochondria targeting.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the charge parameter of the fluorescent dye from positive (cationic) to neutral. This parameter change fundamentally alters the mechanism of mitochondrial entry from active transport (dependent on membrane potential) to passive diffusion, eliminating the harmful effects on mitochondrial membrane potential.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If neutral fluorescent dyes are used to avoid membrane potential changes, then cell cytotoxicity is reduced, but mitochondria targeting ability is lost

Engineering Contradiction:

Improvecell cytotoxicityVSAvoidmitochondria targeting ability

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The patent applies local quality by modifying specific regions of the fluorescent dye molecule. The dye structure is designed with a neutral charge distribution that allows passive diffusion across the mitochondrial membrane, while maintaining fluorescence properties for detection. This localized structural modification enables both neutral behavior and targeting capability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The neutral fluorescent dye achieves multiple functions: it can passively diffuse across the mitochondrial membrane for targeting, maintain mitochondrial membrane potential, reduce cell cytotoxicity, and provide fluorescence signal for detection. This multi-functionality resolves the contradiction between neutrality and targeting ability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Quantity of substance

If cationic dyes are used for mitochondria imaging, then mitochondria accumulation is enhanced, but cell microenvironment changes occur

Engineering Contradiction:

Improvemitochondria accumulationVSAvoidcell microenvironment changes

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The neutral fluorescent dye utilizes the natural passive diffusion process to enter mitochondria without requiring active transport mechanisms. This self-service approach allows the dye to accumulate in mitochondria through concentration gradients established by mitochondrial metabolism, avoiding disruption of the cell microenvironment while achieving sufficient accumulation for imaging.

Inventive Principle:

Principle #25Self-service

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 amide derivative achieves effective mitochondria targeting without altering the membrane potential, exhibits low cytotoxicity, and allows for long-term cell imaging with high photostability and compatibility, making it suitable for real-time observation of mitochondria.

Implementation Method 1

The neutral dye targets mitochondria independent of the negative charge on the inner mitochondrial membrane

Methodology Applied

Scientific EffectPassive diffusion: Diffusion

Implementation Method 2

fluorescent labeling technology

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Data Source

PatentUS12359121B2Neutral fluorescent mitochondrial marker as amide derivative, and preparation method and use thereof

Publication Date: 2025.07.15 SUZHOU UNIV

AI summary

The present invention relates to a series of neutral fluorescent mitochondrial markers as amide derivatives, and a preparation method and use thereof. The present invention provides for the first time that neutral dyes have excellent mitochondria targeting ability after being bonded to an amide compound. The present invention solves the problems of uncertain organelle targeting ability of the existing fluorescent dyes with a neutral structure and that the neutral dye is a commercial marker for lipid droplets in cells. In the present invention, the organelle targeting ability of a fluorescent dye is regulated by creatively modifying the structure, while the optical performance of the original dye is improved; and the biological properties of the dye are obviously improved after being bonded to an amide compound. Amide compounds are cheap and readily available, which is conducive to controlling the cost of new dyes, thus having great scientific significance and commercial value.