Engineering the surface of carbon dots for enhanced photoluminescence and controlled plasmonic interactions

The design of hybrid nanosystems that integrate distinct optical and electronic properties in a synergistic way represents a key challenge in modern photonics. While a few works have proposed to exploit the interactions with plasmonic nanoparticles to enhance the photoluminescence of carbon dots, achieving satisfactory and consistent results remains a demanding challenge. In this work, nitrogen-doped carbon dots (CDs) are functionalized with polyethylene glycol (PEG) through a hydrothermal route to form a polymeric shell, enabling an improvement of their photophysical properties and allowing control of the plasmonic interactions with silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs). The interaction between PEGylated CDs and metal nanoparticles, driven by electrostatic forces, resulted in a photoluminescence enhancement depending on the interaction distance provided by the different PEG chain lengths. These findings demonstrate that PEGylation stabilizes CDs, improves their optical properties, and facilitates the control of interactions with plasmonic nanoparticles, opening new possibilities for the development of advanced hybrid nanomaterials.