Two-photon fluorescent probes for organelle-specific calcium and pH imaging
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Solution Overview
Problem
Current methods for studying calcium ions in cells using one-photon fluorescence probes face limitations due to limited tissue penetration and autofluorescence, necessitating the development of two-photon probes for deeper and more accurate imaging, particularly for organelle-specific multicolor imaging of calcium ion transport.
Innovation Solution
Development of blue emission two-photon fluorescent probes targeting specific organelles like the cytoplasm, mitochondria, and plasma membrane for calcium ions, and a green emission probe for lysosomal hydrogen ions, utilizing benzoxazole derivatives and specific ion receptors, enabling real-time imaging of calcium and pH changes in live cells and tissues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If one-photon fluorescence probes are used for imaging calcium ions, then fluorescence detection is achieved, but tissue penetration depth is limited and autofluorescence occurs
Solution Approach 1:
The patent changes the excitation wavelength parameter from ultraviolet/blue light (350-500 nm) to near-infrared light (700-900 nm). This parameter change enables deeper tissue penetration while reducing autofluorescence, as near-infrared light experiences less scattering and absorption in biological tissues and excites less endogenous fluorophores.
Solution Approach 2:
The patent replaces one-photon excitation mechanism with two-photon excitation mechanism. This substitution allows simultaneous absorption of two lower-energy photons to achieve the same electronic transition as one high-energy photon, enabling deep tissue imaging with reduced photodamage and enhanced penetration depth.
2Length of stationary object
If two-photon fluorescent probes are developed for deep tissue imaging, then penetration depth and resolution are improved, but the number of available probes remains small limiting multicolor imaging
Solution Approach 1:
The patent segments the imaging system into multiple specialized probes, each optimized for specific organelles and ions. By developing distinct two-photon probes with different emission colors (blue, green, red) and organelle-targeting moieties, the system achieves multicolor imaging capability while maintaining deep tissue penetration.
Solution Approach 2:
The patent creates a universal two-photon probe platform that can detect multiple targets (calcium ions, hydrogen ions) in multiple organelles (mitochondria, lysosomes, cytoplasm) using near-infrared excitation. This multi-functional approach enables simultaneous multicolor imaging of various biological processes in deep tissue.
3Measurement precision
If conventional fluorescent probes are used, then calcium ion detection is achieved, but photobleaching and phototoxicity occur during imaging
Solution Approach 1:
The patent replaces one-photon excitation with two-photon excitation using near-infrared light. This substitution concentrates excitation energy to a smaller focal volume, reducing photobleaching and phototoxicity in out-of-focus regions while maintaining high signal-to-noise ratio for calcium ion detection.
Solution Approach 2:
The patent employs pulsed laser excitation for two-photon imaging, delivering energy in short bursts rather than continuous illumination. This periodic action reduces cumulative photodamage and photobleaching while maintaining sufficient excitation intensity for high-resolution calcium imaging.
4Measurement precision
If organelle-specific probes are developed, then specific organelle imaging is achieved, but probe design complexity increases
Solution Approach 1:
The patent merges three functional components into a single integrated probe molecule: (1) fluorophore for signal generation, (2) ion-receptor moiety for calcium/hydrogen ion binding, and (3) organelle-targeting moiety for mitochondrial or lysosomal localization. This merging achieves organelle-specific detection while managing design complexity through modular construction.
Solution Approach 2:
The patent applies local quality by assigning specific functional regions to different parts of the probe molecule. The fluorophore provides optical properties, the ion-receptor provides ion-selective binding at a specific site, and the targeting moiety provides organelle-specific localization, allowing each component to optimize its function independently.
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 probes allow for high-resolution, low-cytotoxicity, pH-independent imaging of calcium ions in specific organelles and simultaneous monitoring of calcium and hydrogen ion distribution, overcoming the limitations of one-photon microscopy by enabling deeper tissue imaging with reduced photobleaching and phototoxicity.
Implementation Method 1
The two-photon microscopy has advantages of higher spatial resolution, less photobleaching, and less phototoxicity than one-photon microscopy currently widely used
Implementation Method 2
Fluorescence imaging using fluorescent probes such as Fluo-4, Fura-2, Rhod-2, or Calcium Green-1 is the most common method to study Ca2+ biology in the cell
Data Source
AI summary
Disclosed are organelles-specific two-photon fluorescent probes, and more particularly, a blue emission two-photon fluorescent probe capable of selectively detecting calcium ions (Ca2+) through fluorescence signals by targeting the cytoplasm, mitochondria, and plasma membrane even among the organelles, respectively, and a green emission two-photon fluorescent probe capable of selectively detecting hydrogen ions (H+) through fluorescence signals by targeting the lysosome, a method for preparing these two-photon probes, and a method for separately or simultaneously imaging calcium ions in the cytoplasm, mitochondria, or plasma membrane and hydrogen ions in the lysosome using the two two-photon probes.