Back to Projects

Smart Imaging Probes, Emerging Imaging

Luminescent/PET-active quantum dots for multimodal imaging

Project ID: 2020_020

1st Supervisor: Mark Green, King’s College London
2nd Supervisor: Phil Blower, King’s College London
Clinical Champion: Sarry Barrington, King’s College London

Aim of the PhD Project:

  • To manufacture new luminescent quantum dots based on cadmium-free structures.
  • To coordinate F-18 to the surface of the structures, making them both PET-active and luminescent. – To use structures in optical imaging and PET imaging, notably sentinel lymph node mapping or any other direction as suggested by the surgical champion.

Project Description / Background:

New imaging agents are emerging with multimodal capabilities, allowing imaging of disease states at different scale lengths and different tissue depths, resulting in quicker and more accurate diagnoses. Quantum dots (QDs) have emerged as the premier nanomaterial for cellular imaging, having bright, stable and tuneable emission, offering numerous benefits over traditional organic dyes. The particles, however, only offer optical emission as an imaging capability which means other, powerful and complimentary techniques are over-looked.

In this project, we will develop a heavy metal-free quantum dot system based on indium phosphide (InP), with inherent stable emission tuneable over the visible spectrum. These particles have the benefit of being considered ‘heavy metal-free’, in contrast to classical cadmium containing materials which present a major hindrance in realising QD applications in routine hospital and clinical settings. Currently, InP based biological imaging agents are beginning to emerge on the market.

A major advantage of InP-based materials is their coordination with fluorine (in the form of HF or NH4F, for example), which fills surface defects and enhances QD emission. This surface etching is considered a key method for improving the optical properties of InP QDs. In this project, we will use the radionuclide F-18 to coordinate to the surface of InP-based QDs providing us with luminescent and PET active materials to be used in imaging. As F-18 decays to oxygen, the final material will be a material with a controlled surface oxide layer, also seen as key component to stable luminescent quantum dots. We therefore not only have a multimodal QD system, but also use the radioactive element, which is readily available and economic, as a method for controllably engineering the surface.

We will also explore the structure of the particle by alloying the material with zinc, and depositing a ZnS shell (before F-19 labelling) with a view to enhancing the emissive profiles, whilst maintaining PET activity. These particles will be used in imaging lymph nodes, with both optical microscopy and PET scans. This project would suit a synthetic inorganic chemist with an interest in biological imaging.

Figure 1: TEM (left) and HAADF-STEM (right) of (In[1] Zn[2] PCdS) with an average diameter of 5.7±1.0 nm.

Back to Projects