Synthesis of Conductive Polymer Nanoparticles for use in Imaging and Assay Development

Conjugated polymers (CPs) have emerged as promising materials for the production of fluorescent devices. They exhibit semiconducting behaviours as they have suitable and structure to allow conduction and the formation of excitons. They possess the ease of processing of plastics, and the electronic behaviour of metals and semiconductors. They have high quantum yields and extinction coefficients in solutions. They can be dissolved in a range of solvents depending on their functionality, and their chemical and physical characteristics can be finely tuned by changing the side groups. Due to their unique properties, it has been proposed that CPs could be used to synthesis nanoparticles that can be used in imaging and drug delivery systems.
This project aims to answer if nanoparticles can be synthesised from CPs, focusing on Poly(3-hexylthiophene-2,5-diyl) (P3HT), Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and Cyano-Polyphenylene vinylene (CN-PPV). If nanoparticles can be synthesis, then the project will aim to address if the CPNs can be used in a Point of Care (POC) assay (as an initial proof of concept). Further development will be to take the CPNs forward for both a bioimaging and treatment application (i.e. can CPNs be used for theranostics).
The first step of the project will be to see if tuneable emission of the CPs can be achieved by a) Studying their characteristics in different solvents (solvatochromism) and b) If a change in the initial concentration of CPs affects emission. The goal will be to have a CP that can be tuned throughout the entire spectrum with narrow, distinct bands.
The second step of the project will be to take the most promising CP and determine if nanoparticles can be synthesised by simple aqueous methods (such as miniemulsion or nanoprecipitation). The project will look at both PEG as a surfactant to make the CPNs water soluble, and also using silica to form cores (or shells) surrounding the CPNs. A wide variety of experiments will be done to determine fluorescence viability and size of nanoparticles.
The third step of the project will to answer if the CPNs surface can be functionalised for antibody conjugation. This will involve testing different conjugation methods (such as adding a thiol or carboxyl group to the CP or silica shell), determining zeta potential of the shell and ultimately determining if antibody can be conjugated to the surface.
Finally, the project will address the question of can the CPNs be used in a POC assay. This will involve optimising and developing the immunoassay for studies with prostate/bowel cancer biomarkers or else bacterial growths in patients with impaired lung function.
By using CPs which can be synthesised with relatively simple aqueous chemistry, and are more biocompatible compared to heavy metal QDs, the ultimate goal is to translate the CPNs into an assay for proof of concept. This can then be taken forward as a potential theranostic application.