Simple Fabrication and Biological Evaluation of Ulva australis-Derived Marine Carbon Dots with Anti-Inflammation, Anti-Oxidation, and Anti-Adipogenesis Features

The overabundance of Ulva australis (U. australis), a green macroalga widespread along the coastline of Jeju Island, Republic of Korea, presents a growing ecological challenge, as it can cause unpleasant odors and disturb the ecological balance. Hence, we report a sustainable valorization strategy for converting U. australis biomass into marine carbon dots (MCDs) via a facile hydrothermal carbonization process. The synthesis requires no hazardous reagents or complex instrumentation and yields highly water-dispersible MCDs with excitation-dependent fluorescence properties. Comprehensive in vitro and in vivo assessments revealed the multifunctional bioactivity of the synthesized MCDs. Moreover, in vivo fluorescence imaging at seven days post-fertilization revealed the preferential accumulation of MCDs along the vertebral column, implying a possible affinity for mineralized tissues and suggesting their utility in skeletal imaging applications. Collectively, these findings underscore the potential of U. australis-derived MCDs as biocompatible and multifunctional nanomaterials with broad biomedical applications.