Bioinspired β-Cyclodextrin-Derived Carbon Dots with Emissive and Photothermal Properties as Nanocarriers for Bioactive Agents

Carbon-based nanostructures are attracting significant interest due to their excellent optical properties, low toxicity, and intriguing applications. Currently, the development of multifunctional carbon-based nanostructures that integrate supramolecular systems is a challenging topic in the advancement of biomedical applications. Here, we report an unprecedented example of carbon nanodots (Cdots) prepared via a one-pot thermal method by heating 2-hydroxypropyl-β-cyclodextrin (HP-βCD) at a mild temperature of 190 °C. The nanostructured Cdots-HPβCD exhibited green luminescence (ϕPL= 0.02), good photothermal conversion efficiency (η = 33%), and a strong bioactive agent loading capability. The Cdots-HPβCD nanostructures were characterized by using spectroscopic techniques and atomic force microscopy. The formation of Cdots-HPβCD/Iodine adducts, iodine release, and antimicrobial effect against Staphylococcus aureus and Klebsiella pneumoniae strains were demonstrated. The geometries and energy interactions of the Cdots-HPβCD/Iodine inclusion complex were investigated through molecular modeling simulations. The versatility of the Cdots-HPβCD as a drug nanocontainer was tested by entrapping other bioactive molecules such as curcumin, ciprofloxacin, and carvacrol. Finally, the low cytotoxicity of the Cdots-HPβCD nanocarrier was confirmed by MTT analysis on the Caco2 cell line, and the interaction with cancer HeLa cell surface was demonstrated by evaluation of the cellular Z potential. The binding of the nanoconstruct to albumin was investigated with steady-state fluorescence. The biofriendly Cdots-HPβCD nanoconstruct by combining the optical properties of the carbon dot core and the drug loading capability of the cyclodextrin shell appears to be a promising candidate for multimodal therapy.