Carbon dots as dual inhibitors of tau and amyloid-beta aggregation for the treatment of Alzheimer's disease.

Alzheimer's disease (AD) is the most common form of senile dementia, presenting a significant challenge for the development of effective treatments. AD is characterized by extracellular amyloid plaques and intraneuronal neurofibrillary tangles. Therefore, targeting both hallmarks through inhibition of amyloid beta (Aß) and tau aggregation presents a promising approach for drug development. Carbon dots (CD), with their high biocompatibility, minimal cytotoxicity, and blood-brain barrier (BBB) permeability, have emerged as promising drug nanocarriers. Congo red, an azo dye, has gathered significant attention for inhibiting amyloid-beta and tau aggregation. However, Congo red's inability to cross the BBB limits its potential to be used as a drug candidate for central nervous system (CNS) diseases. Furthermore, current studies only focus on using Congo red to target single disease hallmarks, without investigating dual inhibition capabilities. In this study, we synthesized Congo red-derived CD (CRCD) by using Congo red and citric acid as precursors, resulting in three variants, CRCD1, CRCD2 and CRCD3, based on different mass ratios of precursors. CRCD2 and CRCD3 exhibited sustained low cytotoxicity, and CRCD3 demonstrated the ability to traverse the BBB in a zebrafish model. Moreover, thioflavin T (ThT) aggregation assays and AFM imaging revealed CRCD as potent inhibitors against both tau and Aß aggregation. Notably, CRCD1 emerged as the most robust inhibitor, displaying IC50 values of 0.2 ± 0.1 and 2.1 ± 0.5 µg/mL against tau and Aß aggregation, respectively. Our findings underscore the dual inhibitory role of CRCD against tau and Aß aggregation, showcasing effective BBB penetration and positioning CRCD as potential nanodrugs and nanocarriers for the CNS. Hence, CRCD-based compounds represent a promising candidate in the realm of multi-functional AD therapeutics, offering an innovative formulation component for future developments in this area. STATEMENT OF SIGNIFICANCE: This article reports Congo red-derived carbon dots (CRCD) as dual inhibitors of tau and amyloid-beta (Aß) aggregation for the treatment of Alzheimer's disease (AD). The CRCD are biocompatible and show strong fluorescence, high stability, the ability to cross the blood-brain barrier, and the function of addressing two major pathological features of AD.

Advancing glioblastoma imaging: Exploring the potential of organic fluorophore-based red emissive carbon dots.

Over time, the interest in developing stable photosensitizers (PS) which both absorb and emit light in the red region (650 and 950 nm) has gained noticeable interest. Recently, carbon dots (CDs) have become the material of focus to act as a PS due to their high extinction coefficient, low cytotoxicity, and both high photo and thermal stability. In this work, a Federal and Drug Association (FDA) approved Near Infra-Red (NIR) organic fluorophore used for photo-imaging, indocyanine green (ICG), has been explored as a precursor to develop water-soluble red emissive CDs which possess red emission at 697 nm. Furthermore, our material was found to yield favorable red-imaging capabilities of glioblastoma stem-like cells (GSCs) meanwhile boasting low toxicity. Additionally with post modifications, our CDs have been found to have selectivity towards tumors over healthy tissue as well as crossing the blood-brain barrier (BBB) in zebrafish models.

Gel-like carbon dots: A high-performance future photocatalyst.

To protect water resources, halt waterborne diseases, and prevent future water crises, photocatalytic degradation of water pollutants arouse worldwide interest. However, considering the low degradation efficiency and risk of secondary pollution displayed by most metal-based photocatalysts, highly efficient and environmentally friendly photocatalysts with appropriate band gap, such as carbon dots (CDs), are in urgent demand. In this study, the photocatalytic activity of gel-like CDs (G-CDs) was studied using diverse water pollution models for photocatalytic degradation. The degradation rate constants demonstrated a remarkably enhanced photocatalytic activity of G-CDs compared with most known CD species and comparability to graphitic carbon nitride (g-C3N4). In addition, the rate constant was further improved by 1.4 times through the embedment of g-C3N4 in G-CDs to obtain CD-C3N4. Significantly, the rate constant was also higher than that of g-C3N4 alone, revealing a synergistic effect. Moreover, the use of diverse radical scavengers suggested that the main contributors to the photocatalytic degradation with G-CDs alone were superoxide radicals (O2-) and holes that were, however, substituted by O2- and hydroxyl radicals (OH) due to the addition of g-C3N4. Furthermore, the photocatalytic stabilities of G-CDs and CD-C3N4 turned out to be excellent after four cycles of dye degradation were performed continuously. Eventually, the nontoxicity and environmental friendliness of G-CDs and CD-C3N4 were displayed with sea urchin cytotoxicity tests. Hence, through various characterizations, photocatalytic degradation and cytotoxicity tests, G-CDs proved to be an environmentally friendly and highly efficient future photocatalyst.