Vitamin E succinate-grafted-chitosan/chitosan oligosaccharide mixed micelles loaded with C-DMSA for Hg2+ detection and detoxification in rat liver

Aim: To determine whether the use of a mixed polymeric micelle delivery system based on vitamin E succinate (VES)-grafted-chitosan oligosaccharide (CSO)/VES-grafted-chitosan (CS) mixed micelles (VES-g-CSO/VES-g-CS MM) enhances the delivery of C-DMSA, a theranostic fluorescent probe, for Hg2+ detection and detoxification in vitro and in vivo. Methods: Mixed micelles self-assembled from two polymers, VES-g-CSO and VES-g-CS, were used to load C-DMSA and afforded C-DMSA@VES-g-CSO/VES-g-CS MM for cell and in vivo applications. Fluorescence microscopy was used to assess C-DMSA cellular uptake and Hg2+ detection in L929 cells. C-DMSA@VES-g-CSO/VES-g-CS MM was then administered intravenously. Hg2+ detection was assessed by fluorescence microscopy in terms of bio-distribution while detoxification efficacy in Hg2+-poisoned rat models was evaluated in terms of mercury contents in blood and in liver. Results: The C-DMSA loaded mixed micelles, C-DMSA@VES-g-CSO/VES-g-CS MM, significantly enhanced cellular uptake and detoxification efficacy of C-DMSA in Hg2+ pretreated human L929 cells. Evidence from the reduction of liver coefficient, mercury contents in liver and blood, alanine transaminase and aspartate transaminase activities in Hg2+ poisoned SD rats treated with the mixed micelles strongly supported that the micelles were effective for Hg2+ detoxification in vivo. Furthermore, ex vivo fluorescence imaging experiments also supported enhanced Hg2+ detection in rat liver. Conclusion: The mixed polymeric micelle delivery system could significantly enhance cell uptake and efficacy of a theranostic probe for Hg2+ detection and detoxification treatment in vitro and in vivo. Moreover, this nanoparticle drug delivery system could achieve targeted detection and detoxification in liver.