Review of Carbon Dot-Based Drug Conjugates for Cancer Therapy

Carbon Dots (CDs) are a class of carbon-based nanostructure known as zero-dimensional nanomaterial and have great potential in the field of targeted chemotherapy. CDs have been extensively explored for bioimaging, sensing, and therapy due to their high quantum yield, low cytotoxicity, high water solubility, good photostability, and tunable excitation wavelength-dependent emission properties. CDs conjugated with various anticancer drugs such as Doxorubicin (DOX), Epirubicin and Temozolomide, Protoporphyrin IX (PpIX), 5-Fluorouracil, Curcumin, Gemcitabine, Methotrexate (MTX), Oxaliplatin, and Cisplatin are explored for chemotherapy applications. These drugs are conjugated with CDs via covalent bond formation such as amide, ester, and hydrazine or with the help of noncovalent electrostatic attraction from opposite charges and hydrogen-bonding interactions. The release of these drug molecules can be controlled with the help of the acidic pH or via highly reactive and abundant small molecular species present in a cancerous environment compared to normal physiological conditions. The CDs-drug conjugate can be specifically released in a targeted manner with the help of a specific substrate attached at the surface and their interaction with overexpressed cell surface receptors. In this review, we demonstrate the application of CDs-drug conjugate toward drug delivery systems for oncology applications.