Abstract

Carbon Dots (CDots) are a vibrant class of fluorescent nanoparticles with tunable physico-chemical and optical properties that owing to their extremely small sizes (<20nm), ease of fabrication, low cost of preparation, unique optical properties, and low cytotoxicity, they hold great promise in a myriad of applications. While their small size enables them to traverse through natural biological barriers, their surface chemical functionalities allow them to efficiently interact with their environment. In addition, CDots have been shown to retain some of the properties of their precursors, also known as active structure preservation during synthesis that has generated interest in exploring the potential applications of CDots.
In this work, we successfully synthesize and transfer the chiral properties of an amino acid precursor (L- and D-proline) to the surface of the CDots. The retention of the active sites potentially associated with the antibacterial properties of proline can be achieved by preserving the chirality of proline based CDots, leading to an increased ability to penetrate bacterial membranes. Instead of relying on an empirical one-factor-at-a-time approach to study the influential condition for this goal, we used Response Surface Methodology (RSM) to efficiently optimize the reaction conditions (temperature, time, and molar ratio) with the goal of preserving the maximum residual chiral signal of proline on the surface of CDots. We further evaluated the antibacterial response to the maximum preservation of the chiral properties in CDots versus its absence. Our observations evidence enhanced antibacterial activity for highly chiral samples confirming the correlation of proline activity with its stereochemistry.