Structural characterization of Q10-loaded solid lipid nanoparticles by NMR spectroscopy

Purpose. The structure of loaded solid lipid nanoparticles (SLN) has been studied to elucidate the incorporation of coenzyme Q10. Methods. Solid-state nuclear magnetic resonance (NMR) has been applied as the principal analytical approach. In order to characterize the integration of the active ingredient coenzyme Q10 inside the solid lipid matrix, measurements of the spin-lattice relaxation time in the rotating frame have been performed. Results. A pattern of spin diffusion between protons of the lipid and protons of the coenzyme Q10 has been observed, which indicates two different fractions of the active ingredient: whereas the majority (60%) of the coenzyme Q10 is found to be homogeneously mixed with the solid lipid, the residual amount of 40% clearly forms a separate, solid phase associated to the particles. Conclusions. A large portion of the active ingredient has been integrated homogeneously. Another, smaller fraction forms separate domains on the nanometer scale.