Luminescent quantum-dot-sized conjugated polymernanoparticles—nanoparticle formation in a miniemulsion system

Abstract

The synthesis of semiconducting polymer nanospheres (SPNs) by miniemulsion methods has been reported previously,^1,2 however the resulting materials have typically been significantly larger than quantum dots, the nanomaterial of choice for cell imaging. In the current work, we aimed to obtain quantum-dot-sized poly(ethylene-glycol) (PEG) functionalised SPNs by optimising the miniemulsion method reported previously.^1,3 We report that PEG functionalised SPNs with a narrow distribution of quantum dot sizes were successfully synthesised, with mean diameters ranging between 2 and 5 nm. PEG-dithiol was also used in one variant of the syntheses, allowing the purified sample to be examined by mass spectrometry (using sulfur as a reporter), confirming the inclusion of a significant number of PEG molecules in the nanoparticles. Also, the presence of PEG was found to significantly affect the yield of the reaction, suggesting it played a role in nanoparticle formation. The nanoparticles were characterized by TEM, absorption and emission spectroscopy, and were found to be stable in solution for months.