Carbon dots and their role in cancer immunotherapy: Targeted drug delivery and tumor microenvironment modulation-a narrative review

Nanomedicine has received great attention over the years with the introduction of innovative materials for drug delivery systems. A class of carbon-based nanomaterials, carbon dots (CDs), have been shown to be an attractive candidates for drug delivery and therapeutics. This review focuses on the properties, synthesis, and functionalization, and biomedical applications of CDs with an emphasis on providing drug delivery efficacy and safety. Due to their unique luminescence behavior and nanoscale size, the biocompatibility properties of CDs can enable targeted therapeutic delivery and in-situ monitoring toward real-time applications, making them as potential outstanding alternatives to common nanocarriers. Among various synthesis strategies, bottom-up and top-down approaches have profound consideration for CDs synthesis, dictating their physical properties and corresponding applications. Before exploiting CDs in drug delivery applications, the functionalization has performed for CDs to achieve precise biocompatibility and drug interaction. Besides, their applications in targeted cancer theranostics and gene delivery are also addressed to show their permeability on biological barriers bearing the potential for therapeutic delivery. Although CDs offer many advantages, issues regarding biocompatibility, possible toxicity and scale-up production are discussed and require attention to help expedite the transition of exosomes and MVs from bench to bedside. Accordingly, this review highlights recent progress and perspectives on the application of CDs to assay for opportunities for future investigations focusing on the clinical potential of CDs in practice.