Engineering mitoxantrone-conjugated graphene quantum dots for advanced photoluminescent cancer therapy

This study investigates the optoelectronic and photoluminescence properties of graphene quantum dots (GQDs) conjugated with the Mitoxantrone (MTX) drug, aiming to enhance cancer drug delivery systems. Using DFT and TDDFT numerical simulations, we examined the impact of GQD size and MTX coupling positions (C–C, C–O, and C–N bonds) on the physical behaviour of DSGQDs. Our study confirm that all structures are energetically stable, as evidenced by the absence of negative frequencies in the IR spectra. Besides, C–O conjugated structures are found to be the most chemically stable as it was shown by global reactivity indices results. Functionalization leads to a reduced H–L energy gap, depending on the MTX coupling position and GQD size. Importantly, the optical properties of GQDs remain largely unaffected by conjugation, maintaining their stability as drug carriers. Larger GQD systems retained stable absorption and photoluminescence characteristics within the near-infrared (NIR) range, while smaller systems exhibited a shift from the visible to the NIR range. Notably, the C₄₈H₁₈ + MTX system with C–O bonding demonstrated superior photoluminescence performance confirmed by the small line width results. These results suggest that GQDs conjugated with MTX hold significant potential for targeted cancer therapy, with minimal interaction between the drug and the GQD host, thereby reducing toxicity risks.