Graphene oxide-assisted synthesis of N, S co-doped carbon quantum dots and surface polymerization as a thermosensitive nanocarrier for near-infrared light-triggered letrozole delivery

Breast cancer treatment greatly benefits from targeted drug delivery systems, which increase therapeutic accuracy, reduce harm to healthy tissues, and enhance patient outcomes by delivering medications directly to the tumor site. A thermosensitive carrier was developed for letrozole (LTZ) delivery through free radical polymerization between N-vinylcaprolactam and allyl alcohol after graphene oxide-assisted nitrogen and sulfur co-doping of carbon quantum dots synthesis. The nanocomposite was characterized using various techniques. LTZ adsorption optimization was performed using response surface methodology (RSM) based on a central composite design (CCD). The performance of the RSM-CCD model was evaluated by examining the correlation coefficient along with several statistical error metrics, including root mean square error, average relative error, hybrid fractional error function, and Chi-square tests. The optimal drug adsorption conditions were determined through CCD analysis to reach a maximum efficiency of 87.92 % at pH 5, over a contact time of 30 min, with a temperature of 25 °C, using a drug solution concentration of 20 μg mL⁻¹. The adsorption isotherm data showed the best fit with the Langmuir model, and the kinetic analysis confirmed agreement with the pseudo-second-order model. The developed thermosensitive nanocarrier has shown exceptional drug release efficiency, achieving 71 % release at 45 °C (pH 7.4), closely following the zero-order kinetic model (R² = 0.9960). Under near-infrared laser irradiation, the nanocarrier showed remarkable photothermal properties, significantly enhancing drug release by approximately 90 % within 15 min. This innovative nanocarrier combines thermosensitive and photothermal capabilities, offering a promising approach for controlled and targeted drug delivery in biomedical applications.