Two-Photon Probe for Intracellular Magnesium Ion Imaging
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Solution Overview
Problem
Current one-photon fluorescent probes for two-photon microscopy have limited penetration depth and suffer from mistargeting issues due to small two-photon action cross sections and membrane-binding, making it difficult to distinguish cytosolic and membrane-bound signals effectively for real-time imaging of intracellular magnesium ions.
Innovation Solution
A two-photon probe with a 2-acetyl-6-(dimethylamino)naphthalene chromophore and o-aminophenol-N,N,O-triacetic acid binding site, designed to enhance two-photon fluorescence efficiency and spectral shifts, allowing for selective imaging of intracellular magnesium ions by forming complexes that emit fluorescence in different wavelength ranges based on environmental polarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If one-photon fluorescent probes are used for two-photon microscopy, then fluorescence detection is possible, but the two-photon action cross section is small leading to limited penetration depth and weak signal
Solution Approach 1:
The patent modifies the molecular structure of fluorescent probes by introducing electron-donating groups (dimethylamino group) and extending conjugation systems (naphthalene chromophore) to enhance two-photon absorption cross-sections. This structural parameter change enables stronger two-photon excited fluorescence while maintaining cell permeability and Mg2+ selectivity
Solution Approach 2:
The patent creates composite fluorescent probe molecules combining multiple functional units: a naphthalene chromophore for two-photon absorption, o-aminophenol-N,N,O-triacetic acid for Mg2+ binding, and acetoxymethyl ester groups for cell membrane permeability. This composite structure integrates multiple functions into a single molecule that can penetrate cells and provide strong two-photon fluorescence signal
2Quantity of substance
If membrane-bound probes are used for imaging, then probe accumulation in membranes occurs, but mistargeting problem arises making it difficult to separate cytosolic and membrane-bound signals
Solution Approach 1:
The patent extracts the carboxylic acid groups from the probe structure and converts them to acetoxymethyl ester groups. This extraction of ionizable groups eliminates the probe's affinity for membranes while maintaining cell permeability, thereby separating the probe's distribution exclusively to the cytosolic compartment and eliminating mistargeting artifacts
Solution Approach 2:
The patent modifies specific local regions of the probe molecule by converting carboxylic acid groups to ester groups, while preserving the Mg2+ binding site integrity. This localized modification changes the probe's membrane interaction properties without affecting its ion-binding capability, enabling selective cytosolic imaging
3Illumination intensity
If probes with high membrane affinity are used, then strong fluorescence signal is obtained from membranes, but it becomes practically difficult to separate membrane-bound probe signals from probe-Mg2+ complex signals
Solution Approach 1:
The patent removes the membrane-binding capability by extracting carboxylic acid groups and replacing them with ester groups. This eliminates membrane fluorescence signal entirely, preventing contamination of cytosolic Mg2+ measurement data with membrane-bound probe signals
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 bright two-photon excited fluorescence with 17-fold enhancement in response to Mg2+, enabling selective detection and quantitative analysis of intracellular magnesium ions with minimal contribution from membrane-bound probes, suitable for deep tissue imaging.
Implementation Method 1
TPM employing two near-infrared photons for excitation offers a number of advantages over one-photon microscopy
Implementation Method 2
a two-photon probe that has a sufficiently low molecular weight to stain cells and is suitable for real-time imaging of intracellular magnesium ions due to its very high two-photon fluorescence efficiency
Data Source
AI summary
A two-photon probe for real-time monitoring of intracellular magnesium ions is provided. Specifically, the two-photon probe is represented by Formula 1:wherein R is H or CH2OCOCH3.The two-photon probe is very suitable for real-time imaging of intracellular magnesium ions. The two-photon probe shows 17-fold two-photon excited fluorescence enhancement in response to Mg2+, which is 7-fold stronger than commercial probes, thus enabling staining of cells in a greatly reduced amount. In addition, the two-photon probe has a sufficiently low molecular weight to stain cells and is very suitable for monitoring Mg2+ ions present in the deep tissue. Furthermore, the two-photon probe can be effectively used for the quantitative as well as qualitative detection of intracellular magnesium ions. Further provided are a method for preparing the two-photon probe and a method for real-time monitoring of intracellular magnesium ions using the two-photon probe.