LiF@SiO₂ nanocapsules for controlled lithium release and osteoarthritis treatment

Electrolytes can be taken orally or intravenously as supplements or therapeutics. However, their therapeutic window may exceed the serum toxicity threshold, making systemic delivery a poor option. Local injection is also not adequate due to rapid diffusion of electrolytes. Here, we solved this issue with a nanocapsule technology, comprising an electrolyte nanocrystal as the drug filling and a silica sheath to regulate drug release rates. In particular, we prepared LiF@SiO₂ nanocapsules and investigated their potential as a delivery system for lithium, which was shown in recent studies to be an effective therapeutic agent for osteoarthritis (OA). We demonstrated that LiF@SiO₂ can extend lithium release time from minutes to more than 60 h. After intra- articular (i.a.) injection into a rat OA model, the nanocapsules reduced the Osteoarthritis Research Society International (OARSI) score by 71% in 8 weeks while inducing no systemic toxicity. Our study opens new doors for improved delivery of electrolyte therapeutics, which have rarely been studied in the past.