ESIPT Fluorogenic Beta-Lactamase Substrates for Antibiotic Detection
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Solution Overview
Problem
Current probes for detecting β-lactamase activity, particularly carbapenemase, are either expensive or fail to ensure high sensitivity due to low accumulation of the fluorescent signal at the detection site, and existing methods like PCR are costly and time-consuming.
Innovation Solution
Development of novel β-lactamase substrates that are stable in aqueous media, remain non-fluorescent or mildly fluorescent until reacting with β-lactamase, and rapidly fragment into a highly fluorescent small molecule, allowing for intense fluorescence detection with improved signal-to-background ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional fluorophores are used for detection, then fluorescence emission can be detected, but the Stokes shift is weak which causes tissue auto-fluorescence interference and reduces detection sensitivity
Solution Approach 1:
The patent changes the key parameter of Stokes shift by using ESIPT fluorophores that exhibit a large Stokes shift (exceeding 130 nm and reaching up to 250 nm). This parameter change allows the fluorophore emission to be well-separated from tissue auto-fluorescence, thereby improving detection sensitivity and eliminating interference from endogenous fluorophores.
Solution Approach 2:
The patent replaces conventional fluorophores with ESIPT fluorophores that utilize excited state intramolecular proton transfer mechanism. This substitution introduces a new photochemical mechanism that inherently provides large Stokes shift, replacing the need for complex filtering systems to separate signal from auto-fluorescence background.
2Measurement precision
If fluorescence detection is used instead of absorption detection, then detection sensitivity is improved, but signal accumulation at the detection site is reduced due to diffusion
Solution Approach 1:
The patent exploits the phase transition property of ESIPT fluorophores from soluble state to precipitated solid state. Upon enzymatic cleavage, the fluorophore precipitates as a solid, which concentrates the fluorescent signal at the detection site and prevents diffusion away from the target location, thereby maintaining high signal accumulation while preserving fluorescence detection sensitivity.
Solution Approach 2:
The patent converts the potential harm of fluorophore diffusion (which reduces signal accumulation) into a benefit by designing the fluorophore to precipitate in its active form. The precipitation process, which might seem to remove the fluorophore from solution, actually concentrates the signal at the detection site and prevents further diffusion, thereby improving both sensitivity and signal accumulation.
3Measurement precision
If existing detection methods like PCR are used, then bacterial resistance can be identified, but the process is costly and time-consuming
Solution Approach 1:
The patent replaces complex molecular biology methods like PCR with a direct enzymatic detection method using ESIPT fluorophore substrates. This substitution eliminates the need for DNA amplification, purification, and complex instrumentation, reducing detection time while maintaining the ability to identify bacterial resistance through direct detection of beta-lactamase enzymatic activity.
Solution Approach 2:
The detection system is designed to be self-amplifying through the enzymatic reaction. The beta-lactamase enzyme catalyzes the cleavage of the substrate, releasing the ESIPT fluorophore which then precipitates and concentrates at the detection site, generating a strong fluorescent signal without requiring external amplification steps or complex processing.
4Illumination intensity
If fluorophores are designed to emit in the red or near-infrared region, then tissue transparency is maximized for imaging, but the fluorophore structure becomes more complex
Solution Approach 1:
The ESIPT fluorophore platform provides multi-functionality: it can be designed to emit in the red/near-infrared region for deep tissue imaging, maintains large Stokes shift for auto-fluorescence rejection, and exhibits precipitation behavior for signal concentration. This universal platform addresses multiple requirements simultaneously without requiring separate complex structures for each function.
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 substrates enable rapid and sensitive detection of β-lactamase activity with enhanced signal retention at the enzyme activity site, facilitating effective identification of antibiotic-resistant bacteria without the need for extensive sample preparation or high costs.
Implementation Method 1
the class of fluorophores leading to an intramolecular proton transfer in an excited state, called ESIPT (for 'Excited State Intramolecular Proton Transfer')
Implementation Method 2
an enzyme, a beta-lactamase, which facilitates the hydrolysis of the antibiotic's beta-lactam ring
Implementation Method 3
the degree of accumulation of the fluorescent signal at its production site (and, therefore, to the diffusion rate from this site, and to the question of knowing if the fluorophore precipitates or not)
Data Source
AI summary
Probes for the detection of β-lactamase-type enzymatic activity. In particular, novel fluorogenic substrates for detecting the presence of a catalytically active β-lactamase and a detection method using such substrates.