Phenyleneethynylene Macrocycles for Live Cell Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conjugated polymers and nanoparticles face limitations in intracellular applications due to large molecular weights and broad molecular weight distributions, which hinder their efficient entry and labeling of live cells, while short conjugated oligomers offer advantages but require modification for targeting and sensing functions.
Innovation Solution
The development of phenyleneethynylene macrocycles (PEMCs) with specific structures and functional groups allows for efficient intracellular labeling by forming macrocyclic imines and subsequent protonation, enhancing water solubility and fluorescence, enabling targeted and non-toxic cellular entry and nucleic acid staining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conjugated polymers (CPs) are used for fluorescent labeling, then high molar absorptivity and photostability are achieved, but large molecular weight and broad molecular weight distribution limit intracellular applications
Solution Approach 1:
The patent segments the conjugated polymer into discrete oligomeric units (trimers, tetramers, pentamers) with defined chain lengths. This segmentation maintains the photophysical properties of CPs while reducing molecular weight to a controlled range (500-2000 Da), enabling efficient cellular uptake without sacrificing photostability
Solution Approach 2:
The patent systematically varies the oligomer chain length (n=0 to 4 in the formula) and side chain composition to optimize the balance between photostability and molecular weight. By controlling the degree of polymerization to specific oligomeric states rather than using high molecular weight polymers, the invention achieves the desired parameter optimization
2Speed
If short conjugated oligomers (COs) are used for intracellular labeling, then fast diffusion through cell membranes is achieved, but modification with functional groups is required to achieve targeting and sensing functions
Solution Approach 1:
The patent incorporates multiple functional groups (carboxylic acid, amine, hydroxyl, thiol, amide, guanidine) directly into the oligomer structure through the side chain design. This multi-functionality allows the same oligomer core to serve multiple purposes: cellular entry, targeting, sensing, and imaging, eliminating the need for separate modification steps while maintaining fast cellular uptake
Solution Approach 2:
The patent merges the fluorescent core, side chains with cellular entry functions, and targeting/sensing functional groups into a single integrated oligomeric molecule. This consolidation achieves multiple functions simultaneously without requiring sequential modifications, reducing overall complexity
3Quantity of substance
If conjugated polymers are used for fluorescent labeling, then high molar absorptivity is achieved, but broad molecular weight distribution limits intracellular applications
Solution Approach 1:
The patent segments the polymer into discrete oligomeric units with specific chain lengths (dimers, trimers, tetramers, pentamers). This segmentation transforms the broad molecular weight distribution of polymers into a narrow, controlled distribution of oligomers, while maintaining high molar absorptivity through the preserved conjugated backbone structure
Solution Approach 2:
The patent employs Stille coupling reaction conditions that enable precise control over the degree of polymerization, producing oligomers with narrow molecular weight distributions. The controlled coupling conditions ensure uniform oligomer formation rather than the broad distribution typical of conventional polymerization
4Ease of operation
If conjugated polymers are endocytosed and entrapped in endosomes or lysosomes, then cellular entry is achieved, but intracellular labeling efficiency is reduced
Solution Approach 1:
The patent creates small, flexible oligomers that dynamically adapt their size and shape to pass through cell membranes via diffusion rather than static endocytosis pathways. This dynamic cellular entry mechanism allows direct cytoplasmic delivery without endosomal/lysosomal entrapment, significantly improving labeling efficiency while maintaining ease of cellular uptake
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
PEMCs exhibit high quantum yields, fast cellular entry, and selective RNA binding, with minimal toxicity, significantly improving intracellular labeling efficiency and specificity compared to traditional conjugated polymers and oligomers.
Implementation Method 1
combining a monodispersed di-aldehyde end-capped oligophenyleneethynylene with a polyamine to form a macrocyclic imine
Implementation Method 2
followed by reduction of the imine to an amine
Implementation Method 3
whereupon irradiation the PEMC fluoresces from within the live cells
Implementation Method 4
retain the advantageous of a high absorbance of the CPs
Implementation Method 5
The PEMC can have the amines of the cyclic oligo (oligophenyleneethynylene-co-polyamine) in the form of an ammonium ion paired with a anion from the acid used for protonation
Data Source
AI summary
A phenyleneethynylene macrocycle (PEMC) is constructed that is a cyclic or polycyclic oligo (oligophenyleneethynylene-co-polyamine) where a monodispersed oligophenyleneethynylene is coupled with a polyamine. The PEMC is formed by coupling a monodispersed di-aldehyde end-capped oligophenyleneethynylene with a polyamine to form a macrocyclic imine and reducing the imine to an amine. The PEMC is useful at entering living cells for the fluorescence imaging of the living cells without toxicity to the cells.