Versatile Conjugated Polymer Nanoparticles for High-Resolution O2 Imaging in Cells and 3D Tissue Models

Area of Science:

• Nanotechnology
• Biomedical Imaging
• Materials Science

Background:

• Effective nanoparticle probes for live cell imaging require high brightness, photostability, and tunable properties.
• Current probes often face limitations in resolution and quantitative oxygen (O2) detection.

Purpose of the Study:

• To develop and characterize novel conjugated polymer-based phosphorescent nanoparticles for high-resolution O2 imaging.
• To evaluate the brightness, stability, cell compatibility, and imaging capabilities of these nanoparticles.

Main Methods:

• Synthesis of polyfluorene or poly(fluorene-alt-benzothiadiazole) copolymers with covalently bound phosphorescent metalloporphyrins (PtTFPP, PtTPTBPF).
• Nanoparticle preparation via precipitation, followed by characterization of optical properties, stability, and cell toxicity.
• Modulation of cell-staining properties using charged groups and evaluation of cell entry mechanisms and in vivo distribution.

Main Results:

• The synthesized nanoparticles exhibit enhanced brightness (>5-10 times) under one- and two-photon excitation.
• Nanoparticles demonstrate excellent stability, low cell toxicity, and compatibility with ratiometric and lifetime-based imaging.
• Tunable cell-staining properties were achieved, with zwitter-ionic versions showing high efficiency and distinct cell entry mechanisms.

Conclusions:

• Conjugated polymer-based phosphorescent nanoparticles are a versatile tool for quantitative O2 imaging.
• These nanoparticles offer superior performance for live cell and 3D tissue models.
• The tunable nature of these probes allows for broad applicability in biological research.