Facile Synthesis of Nitrogen-Doped Carbon Quantum Dots for Bioimaging

Abstract

Precision engineering and rapid optimization paves the way for clinical translation of pristine luminescent nano-materials bestowed with alluring physicochemical properties. However, strategic control over the structural attributes are essential while preserving their crystallinity for exploring their biophysical and therapeutic properties at the nanoscale. Here, an attempt has been made to control the synthesis of fluorescent nitrogen-doped carbon quantum dots (FNCQDs) through hydrothermal carbonization route. To maintain the structural integrity and further biophysical properties, the FNCQDs were synthesized from paracetamol (drug) at a hydrothermal temperature of 230 °C, where the solution mixture was kept for 9 hrs until complete carbonization was achieved. Before proceeding to biomedical applications, the quantum yield, morphology, elemental composition, and poly dispersive index (PDI) was computed. The as-synthesized FNCQDs appeared as spherical (5.8 nm) under the high resolution transmission electron microscope (HR-TEM). It also exhibited quantum yield (QY) of 15.9% and PDI of 0.512. The FNCQDs exhibited superb photostability with bright blue fluorescence (FL). To confirm their biological interventions, the haemocompatibility assays and circular dichroism (CD) was performed. FNCQDs displayed higher cytocompatibility towards human RBCs’ (10-500 μg/mL). CD measurements demonstrated insignificant changes in the α-helical content of plasma upon association with fluorescent dots. The synergistic interplay of physical simulations accompanied with robust scalable synthesis and material characterization techniques inspires model-driven design of a novel nanomedicine in versatile biomedical applications ranging from multi-modal imaging to cancer therapy.