Gelatin-based carbon quantum dot-molecularly imprinted polymer: Safe photoluminescent core-shell nano-carrier for the pH-responsive anticancer drug delivery.

This study aims to synthesize a core-shell gelatin-based carbon quantum dot-molecularly imprinted polymer (MIP@g-CQD) via the precipitation free-radical polymerization process using methotrexate (MTX) as a model anticancer template. To investigate the efficiency of the prepared photoluminescent MIP@g-CQD as a pH-responsive nano-carrier, MTX was loaded into MIP@g-CQD by soaking in a drug solution and the release behavior of the loaded drug was evaluated in the necessary pH values (7.4, 5). The successful synthesis of materials was characterized using PL, TEM, FE-SEM, DLS, and FT-IR analyses. Interestingly, the created cavities in the core-shell nano-carriers can interact with the MTX molecules effectively, leading to an increase in the loading capacity. According to the obtained results from Langmuir adsorption isotherms, the imprinting factor was calculated (IF = 4.91). Also, the binding kinetics of MTX revealed the creation of particular recognition sites in the core-shell polymeric network. The MTX-loaded MIP@g-CQD displayed a low rate and limited release at the simulated physiological environment (pH 7.4, 37 °C), but it is increased at tumor tissue (pH 5, 41 °C) conditions, which can lead to long-term and sustained release of MTX in the desired target. This property of MIP@g-CQD could avoid the release of MTX in normal physiological conditions, decreasing the possible side effects of MTX drug. Owing to the existence of amide functional groups in the nano-carrier structure and its negatively charged nature, the MTT assay displayed desirable cytotoxicity against the breast cancer cell line (MCF-7) for the MTX-loaded nano-carrier. According to the obtained results, the prepared safe photoluminescent MIP@g-CQD with appropriate pH-responsivity has a high ability to be applied as an anticancer and bio-detection agent.