Medical Imaging

EPSRC Centre for Doctoral Training


203 - Ultra-bright magnetic organic semiconductor nanoparticles for multimodal imaging

1st Supervisor: Mark Green
2nd Supervisor: James Wilton-Ely

Aim of the PhD Project:

The project aims to prepare conjugated polymer nanoparticles with novel structures (doped with iron oxide, core/shell and alloys/blends) using a range of commercially unavailable ultra-bright conjugated polymers provided by the world’s leading conjugated polymer producer (CDT, Cambridge Display Technology). These particles will be used for optical and MRI Imaging.

Project description / background:

Conjugated polymer nanoparticles are an attractive alternative to quantum dots in imaging due to the lack of heavy metal or inorganic decomposition products. Such particles, often referred to as SPNs (semiconducting polymer nanoparticles) or P-dots (polymer dots) are generally much brighter than inorganic quantum dots, easier to prepare and have, to-date, shown no toxicity issues that prevent their routine use or ultimate clinical applications. The MG group has developed much of the chemistry behind SPN synthesis, which is now being commercialised through KCL. One of the most promising materials being developed is iron oxide-doped SPNs that can be manipulated by a magnet, giving bright emission and ease of purification with an MRI active element. Whilst brightly emitting, the luminescence is still significantly quenched with the introduction of the metal oxide, and whilst still comparable to quantum dots, this is an unwanted side effect.

In order to combat this, we have worked in collaboration with Cambridge Display Technology, the world leaders in conjugated polymer synthesis, and have access to some of the purest, brightest polymers so far created. Using these materials, we will synthesis a range of conjugated polymer nanoparticles using these new polymers to generate ultra-bright optical imaging agents with further MRI functionality incorporated.

SPNs are much simpler to prepare than existing optical probes, yet are some of the most efficient optical imaging materials currently available. We will borrow ideas from QD structures and we will develop a core/shell structure, whilst still incorporating the iron oxide, placing a wide band gap conjugated polymer on top of our existing particles. This will further increase the brightness of the emission as charge carriers are forced to recombine in the core emitting particle.

We will also explore mixing conjugated polymers, making polymer blend particles which have been shown to increase emission brightness (this is analogous to alloy quantum dot particles). A further imaging agent (iron oxide) will be added to the blend particle, resulting in bright optical/MRI active materials.