Engineering Two-in-One Nanoparticles for Simultaneous Delivery of Graphene Quantum Dot and Pemetrexed

The simultaneous delivery of therapeutic agents and imaging probes using polymeric nanoparticles (NPs) has gained significant attention for cancer treatment. In this work, we developed a multifunctional nanocarrier system composed of an amphiphilic block copolymer, poly-(2-ethyl-2-oxazoline)-b-poly-(ε-caprolactone) (PEtOx-b-PCL), and dimethyldidodecylammonium bromide (DDAB), for the codelivery of the chemotherapeutic drug pemetrexed (PMT) and nitrogen- or sulfur-doped graphene quantum dots (N-GQDs or S-GQDs) as fluorescent probes. Critical formulation parameters were optimized using a central composite design (CCD). The optimized NPs exhibited favorable physicochemical properties, including positive surface charge (6-8 mV), hydrodynamic diameters of ∼140 nm, and high encapsulation efficiency for both PMT (46-56%) and GQDs (>98%). In vitro assays revealed that PMT-loaded nanoparticles (NPs) significantly enhanced cytotoxicity against MCF-7 cells. At a concentration of 2 ppm after 72 h, N-PMT NPs and S-PMT NPs inhibited cell proliferation by 50.7% and 53.8%, respectively, compared to 37.8% inhibition with free PMT at the same dose. Confocal microscopy confirmed efficient intracellular uptake and strong fluorescence signals, supporting their potential for bioimaging. Collectively, these results demonstrate that this two-in-one nanocarrier system significantly enhances chemotherapeutic efficacy while enabling real-time imaging, establishing a promising platform for drug delivery and noninvasive treatment monitoring in cancer nanomedicine.