Nitrogen doped carbon quantum dots: a multifaceted carbon nanomaterial that interferes in an amyloid-forming trajectory

Carbon quantum dots (CQDs) are a versatile class of carbon-based nanomaterial frameworks that have previously been used as a diagnostic device, in sensing for environmental applications, in bioimaging, and for drug delivery systems. Their versatility stems from their ability to be chemically tailored <i>via</i> functionalization to optimize properties for specific applications. In this study, we have synthesized lactic acid-derived nitrogen doped carbon quantum dots (LAdN-CQDs) and examined their ability to intervene in the conversion of soluble, monomeric hen egg-white lysozyme (HEWL) into mature fibrils. Our data indicate that LAdN-CQDs inhibit HEWL fibril formation in a dose-dependent manner (achieving up to 50% inhibition at 2.5 mg mL^-1). Furthermore, in a neuroblastoma-derived cell line, LAdN-CQDs were found not to disrupt mitochondrial membrane potential or trigger apoptosis at the same concentration range, suggesting that they are biocompatible. LAdN-CQDs effectively neutralized reactive oxygen species (ROS), with a 50% decrease in ROS levels at just 100 μg mL^-1 when challenged with an established free radical generator and protected the cell line from rotenone-induced apoptosis. The ability of LadN-CQDs to inhibit the soluble-to-toxic transformation of HEWL, the tolerance of SHSY-5Y cells to LAdN-CQDs, and their ability to restitute cells from rotenone-induced apoptosis, combined with the biocompatibility findings, suggest that LAdN-CQDs are potentially neuroprotective. The findings indicate that LAdN-CQDs represent a versatile, carbon-based, sustainable nanoplatform that bridges nanotechnology and neuroprotection, promoting the development of green chemistry-based healthcare solutions.