Rhodamine pH Sensors With Fast Neutral-pH Fluorescence
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Solution Overview
Problem
Existing pH sensor dyes do not provide a signal at neutral pH and lack fast response to pH changes, making them unsuitable for monitoring intracellular processes and requiring water solubility and a pKa relevant to the tested pH.
Innovation Solution
Novel rhodamine compounds utilizing the spirolactam to ring-opened amide process for pH sensing, with specific alkyl, substituted alkyl, and linker configurations, enabling fluorescent emission for pH determination and monitoring cellular processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acidic pH sensor dyes are used, then they fluoresce brightly in acidic environments, but they do not produce a signal at neutral pH
Solution Approach 1:
The patent modifies the pKa value of the pH sensor dye by introducing electron-donating groups (such as methoxy, amino, or hydroxy groups) at specific positions on the xanthene ring system. This chemical modification shifts the transition pH range from purely acidic to cover neutral and slightly basic ranges, enabling the dye to fluoresce at pH 7-9 while maintaining its pH-sensitive signaling capability.
2Measurement precision
If conventional pH sensor dyes are used, then they can detect pH changes, but they exhibit slow response to pH changes
Solution Approach 1:
The patent introduces a spiro-lactam moiety at the 3-position of the xanthene ring system, creating a local structural feature that enables rapid ring-opening and ring-closing transitions in response to pH changes. This localized structural modification at a specific position enhances the kinetic response speed without compromising the overall fluorescence properties or pH detection range of the dye.
3Adaptability or versatility
If pH sensor dyes are designed for intracellular use, then they must be water-soluble and have relevant pKa, but existing dyes lack fast response and appropriate signaling characteristics
Solution Approach 1:
The patent creates a composite molecular structure combining the xanthene fluorophore core with a spiro-lactam sensing moiety and water-solubilizing substituents. This composite design integrates multiple functional elements: the xanthene provides fluorescence, the spiro-lactam provides rapid pH-responsive conformational change, and the attached substituents (such as carboxylate or sulfate groups) provide water solubility and appropriate pKa for intracellular pH monitoring.
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 compounds offer rapid pH response and fluorescent signaling within cells, allowing for time-dependent measurements of internalization and monitoring of cellular processes.
Implementation Method 1
the spirolactam to ring-opened amide process is utilized for sensing pH... enabling fluorescent emission for pH determination
Implementation Method 2
the spirolactam to ring-opened amide process is utilized for sensing pH... At a pH equal to the pKa of the dye, half of the dye molecules will become fluorescent
Data Source
AI summary
The present disclosure provides for compounds of Formula (I),its corresponding compounds of Formula (II)or salts thereof and their use as fluorogenic pH sensors.