Design of Curcumin Loaded Carbon Nanodots Delivery System: Enhanced Bioavailability, Release Kinetics, and Anticancer Activity

Despite the potential health benefits of curcumin, such as antioxidant, anticancer, anti-inflammatory, and antimicrobial properties, its usage is limited by poor bioavailability and low aqueous solubility. Nano-formulations of curcumin have gained a lot of attention due to their increased bioavailability, solubility, circulation times, targeted specificity, decreased biodegradation, better stability, and improved cellular uptake. The current study aimed to enhance the bioavailability of curcumin using carbon nanodots (CNDs) as loading vehicles to deliver curcumin due to their excellent biocompatibility, aqueous solubility, and photoluminescence properties. Two types of CNDs (E-CNDs and U-CNDs) were used for curcumin loading and characterized for particle size, morphology, loading capability (measured as adsorption efficiency and loading capacity), stability, photoluminescence properties, in vitro drug release studies, cellular uptake, and anticancer activity. The prepared curcumin-loading CNDs (Curc-CNDs) displayed sizes around or below 10 nm with good stability. The Curc-E-CNDs demonstrated a curcumin adsorption efficiency of 91% in solution, while the Curc-U-CNDs have an adsorption efficiency of 82%. Both have a loading capacity of 3.4-3.8% with respect to the weight of the CNDs. Curcumin release followed a controlled sustained pattern that a total of 60% and 74% of curcumin was released at 72 h from Curc-E-CNDs and Curc-U-CNDs, respectively, in pH 5 buffer, and almost 90% was released in culture media within 96 h. Both of the Curc-CNDs were uptaken by cells and exhibited prominent cytotoxicity toward cancer cells. The results clearly depict the role of CNDs as efficient carriers for curcumin delivery with prolonged release and enhanced bioavailability, thereby improving the overall antitumor activity.