Conjugated Polyelectrolytes are Feeling the Heat: A Sensitive Ratiometric Nanothermometer

Temperature is a fundamental variable that controls and drives many chemical, biological and physical processes. Nowadays, there is a tremendous drive to explore and understand processes at the nanoscale level in many fields of science and technology. We report a self-referencing ratiometric nanothermometer based on short conjugated polyelectrolytes (CPEs). The probe is prepared by complexing a phenylene-based polymer with polyvinylpyrrolidone (PVP), an amphiphilic macromolecule that destabilizes the CPE π–π stacking. This makes it possible to shift the equilibrium between the less emissive aggregated state of the CPE (520 nm) and its more emissive single chains (450 nm) within a useful temperature range (15.0–70.0 °C). The probe is used as a noninvasive fluorescent method for mapping thermal fluctuations in hydrogel matrices using an unmodified commercially available digital single-lens reflex camera (DSLR). The reported temperature sensor has the potential to provide a wealth of information when thermal mapping is correlated with chemical or physical processes.

Biography: Dr. Pierre Karam received his PhD from McGill University in 2011 where he worked on developing single molecule fluorescent spectroscopy methods to study macromolecular interactions. He then joined UC Berkeley as a postdoctoral fellow where worked on unravelling the interactions between electrogenic bacteria and microelectrode to improve the efficiency of microbial fuel cells. In 2012, he joined the American University of Beirut an assistant professor of chemistry. His work currently focuses on developing fluorescencebased nanothermometers and sensing assays for specific biomarkers.