Fluorinated graphene quantum dots with long-term lubrication for visual drug loading and joint inflammation therapy

Osteoarthritis (OA) treatment mainly relies on developing new drugs or nanocarriers, while little attention is paid to building novel remedial mode and improving drug loading efficiency. This work reports an integrated nanosystem that not only realizes visual drug loading and release, but also achieves enhanced lubrication and effective joint inflammation therapy based on fluorinated graphene quantum dots (FGQDs). Oxygen introduction promotes FGQDs outstanding water-stability for months, and layered nano-sized structure further guarantees excellent lubricating properties in biomimetic synovial fluid. The special design of chemistry and structure endows FGQDs robust fluorescence in a wide range of pH conditions. Also, the excitation spectrum of FGQDs well overlaps the absorption spectrum of drugs, which further constructs a new concept of internal filtering system to visually monitor drug loading by naked eyes. More importantly, extraordinary long-term lubrication performance is reported, which is the first experimental demonstration of concentration-dependent mutations of coefficient of friction (COF). Cell incubation experiments indicate that drug-loaded FGQDs have good biocompatibility, tracking property of cellular uptake and drug release, which show efficient anti-inflammation potential for H₂O₂-induced chondrocyte degradation by up-regulated cartilage anabolic genes. This study establishes a promising OA treatment strategy that enables to monitor drug loading and release, to enhance long-time lubricating property, and to show effective anti-inflammatory potential for cartilage protection.