Microwave-Assisted Synthesis and AFM Characterization of Chitin- and Chitosan-Derived Carbon Quantum Dots for Biomedical Applications

Effective delivery of therapeutic agents to the central nervous system remains challenging because of the restrictive nature of the blood–brain barrier. Intranasal administration offers a promising non-invasive route for nose-to-brain drug delivery. Chitosan is a biocompatible, biodegradable, and mucoadhesive biopolymer, while chitin is an abundant natural precursor with potential for producing carbon-based nanomaterials. In this study, chitosan- and chitin-derived carbon quantum dots (CQDs) were synthesized using a simple microwave-assisted bottom-up method. The precursor material was dispersed as a heterogeneous slurry in methanol for three hours on a magnetic stirrer, separated by centrifugation, washed with MilliQ water, filtered, and subjected to microwave treatment reaching temperatures higher than 65C. To ensure safety for intranasal application, residual toxic solvents were completely removed via solvent evaporation. The resulting nanoparticles were recovered in ethanol and in water and deposited on freshly cleaved mica for atomic force microscopy characterization. AFM imaging revealed relatively homogeneous nanoparticles with dimensions ranging from approximately 3 to 6 nm. These findings demonstrate that a microwave-assisted procedure can produce nanoscale carbon dots from chitin and chitosan precursors. Their small size, together with the biocompatible origin and potential surface functionality of the precursor materials, supports their further investigation as nanocarriers, fluorescent imaging agents, and biosensing platforms. Due to early stages of protocol development, additional studies will evaluate their chemical composition, fluorescence properties, colloidal stability, drug-loading capacity, prioritizing cytocompatibility, and interactions with biological interfaces relevant to intranasal delivery.