Nanotheranostics for Alzheimer's Disease: The Rising Promise of Fluorescent Carbon Dots

Alzheimer's disease is a commonly observed neurodegenerative disease among older adults worldwide nowadays. It is characterized by a gradual decline in neuronal structural features and function in the brain owing to the aggregation and deposition of prion protein (amyloid beta), hyperphosphorylation of tau proteins, the production of excessive reactive oxygen species, and elevated levels of metal ions. However, various traditional drugs have been developed and used, but some of them have mild or severe side effects, and a few of them are incapable of crossing the complex blood-brain barrier. Due to this reason, these traditional drugs had only modest success in clinical studies. Early diagnosis is also one of the most concerning prospects for Alzheimer's disease treatment. As a result, preparation of such materials capable of crossing the blood-brain barrier and detecting early-stage changes that lead to symptoms in Alzheimer's disease is in demand in the biomedical field. Carbon dots have recently grabbed the attention for the remediation of Alzheimer's and other neurodegenerative diseases, due to their ability to cross the blood-brain barrier because of their zero-dimensional structure, apart from possessing various fascinating properties like, biocompatibility, low cytotoxicity, non-invasiveness, water dispersibility, tunable emission, surface functionalization and, enhanced physicochemical characteristics foster targeted drug delivery, early diagnosis, and higher therapeutic efficacy. In this review, we outline the latest developments in the use of carbon dots for both imaging and therapeutic strategies in Alzheimer's disease, and conclude with a thorough evaluation of their future applications in the management of neurodegenerative diseases.