Monoacyl Fluorescent Probe for Real-Time Protease Detection

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Solution Overview

Problem

Existing fluorescent probes for measuring proteases require multiple steps for fluorescence activation, resulting in poor real-time response and quantification suitability due to the need for hydrolysis of both acyl groups to change from a closed to an open ring structure.

Innovation Solution

A fluorescent probe utilizing a diaminorhodamine structure with a hydroxy(lower alkyl) group substitution, where the carboxyl group on the benzene ring is acylated and then de-acylated, allowing a structural change from a closed to an open ring structure at one reaction site, enabling prompt fluorescence activation at neutral pH.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a diacyl type fluorescent probe is used for measuring protease, then the probe can detect protease activity, but the fluorescence response requires multiple hydrolysis steps resulting in poor real-time response property

Engineering Contradiction:
Improveprotease detection capabilityVSAvoidreal-time response property
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The invention extracts and removes one acyl group from the traditional diacyl probe structure, creating a monoacyl probe structure. This extraction eliminates the need for dual hydrolysis steps while retaining the essential protease recognition and fluorescence activation functions, thereby achieving real-time response.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The probe structure is segmented into essential and non-essential components. The invention identifies that only one acyl group is necessary for both protease recognition and fluorescence activation, separating the functional requirements from the traditional dual-acyl structure and eliminating redundant elements.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If a diacyl type fluorescent probe is used for measuring protease, then the probe can detect protease activity, but the multiple hydrolysis steps result in poor suitability for quantification

Engineering Contradiction:
Improveprotease detection capabilityVSAvoidquantification suitability
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

By extracting one acyl group from the diacyl structure, the invention simplifies the reaction pathway to a single hydrolysis step. This reduction in complexity directly improves quantification suitability while preserving the probe's ability to detect and measure protease activity accurately.

Inventive Principle:
Principle #2Taking out (Extraction)

3Stability of the object's composition

If the carboxyl group on the benzene ring is replaced with a hydroxy(lower alkyl) group and the amino group is acylated, then the probe achieves closed ring non-fluorescent structure, but requires acyl group removal to activate fluorescence

Engineering Contradiction:
Improveclosed ring structure stabilityVSAvoidfluorescence activation process
Core Design Contradiction:
Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The invention modifies the chemical parameters by replacing the carboxyl group with a hydroxy(lower alkyl) group, which fundamentally changes the ring-closing mechanism. This parameter change enables the ring to close through different chemistry, achieving stable non-fluorescent state that can be activated by a single hydrolysis event rather than requiring complex multi-step processes.

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 probe achieves several hundred times higher fluorescence intensity and provides superior real-time response and quantification capabilities for protease measurement, with the open ring form being retained in cells without leakage, enabling long-term sensitive imaging.

Implementation Method 1

hydrolysis of the acyl group at one side by a protease

Methodology Applied
Scientific EffectHydrolysis: Hydrolysis

Implementation Method 2

fluorescent probes are functional molecules which are substantially non-fluorescent in the absence of a target substance, and become fluorescent after a reaction with the target substance

Methodology Applied
Scientific EffectFluorescence: Fluorescence

Data Source

PatentEP2399920B1Fluorescent probe for use in measurement of protease
Publication Date: 2015.03.25 THE UNIV OF TOKYO
  • EP2399920B1 patent drawingFigure 1(a)~1(d)
  • EP2399920B1 patent drawingFigure 2~3
  • EP2399920B1 patent drawing

AI summary

A compound represented by the formula (I) or a salt thereof (R1 represents hydrogen atom, or a substituent; R2 to R7 represent hydrogen atom, hydroxyl group, an alkyl group, or a halogen atom; R8 and R9 represent hydrogen atom, or an alkyl group; X represents a C1-C3 alkylene group; and R10 represents an acyl group), which promptly causes a structural change from a non-fluorescent closed ring structure to a strongly fluorescent open ring structure by hydrolysis of an acyl group, and is useful as a fluorescent probe for measuring a protease showing superior suitability for quantification.