Influence of Pore Size and Surface Functionalization of Mesoporous Silica Nanoparticles on the Solubility and Antioxidant Activity of Confined Coenzyme Q10

Coenzyme Q10 is a potent antioxidant that plays an importantrolein the maintenance of various biochemical pathways of the body andhas a wide range of therapeutic applications. However, it has lowaqueous solubility and oral bioavailability. Mesoporous silica nanoparticles(MCM-41 and SBA-15 types) exhibiting varying pore sizes and modifiedwith phosphonate and amino groups were used to study the influenceof pore structure and surface chemistry on the solubility, in vitro release profile, and intracellular ROS inhibitionactivity of coenzyme Q10. The particles were thoroughly characterizedto confirm the morphology, size, pore profile, functionalization,and drug loading. Surface modification with phosphonate functionalgroups was found to have the strongest impact on the solubility enhancementof coenzyme Q10 when compared to that of pristine and amino-modifiedparticles. Phosphonate-modified MCM-41 nanoparticles (i.e., MCM-41-PO3) induced significantly higher coenzyme Q10 solubility thanthe other particles studied. Furthermore, MCM-41-PO3 ledto a twofold decrease in ROS generation in human chondrocyte cells(C28/I2), compared to the free drug in a DMSO/DMEM mixture. The resultsconfirmed the significant contribution of small pore size and negativesurface charge of MSNs that enable coenzyme Q10 confinement to allowenhanced drug solubility and antioxidant activity.

Automated summary

Coenzyme Q10 is a powerful antioxidant with various therapeutic applications, but it has low solubility and bioavailability. This study investigated the effects of mesoporous silica nanoparticles with different pore sizes and surface modifications on the solubility, release profile, and intracellular antioxidant activity of coenzyme Q10. Surface modification with phosphonate groups significantly enhanced the solubility of coenzyme Q10 compared to pristine and amino-modified particles. Moreover, phosphonate-modified MCM-41 nanoparticles showed the highest solubility and decreased ROS generation in human chondrocyte cells. These findings highlight the importance of small pore size and negative surface charge in improving the solubility and antioxidant activity of coenzyme Q10.