The formulation, characterization and in vivo evaluation of a magnetic carrier for braindelivery of NIR dye

Abstract

This work reports the targeting of the near infrared (NIR) dye indocyanine green (ICG) tothe brain using composite nanoparticles. Thermal decomposition of iron pentacarbonyl wasused to synthesize monodisperse oleic acid coated magnetic nanoparticles (OAMNP).Synthesized OAMNP and ICG were encapsulated in a poly (lactide–co-glycolide) matrixusing an emulsion evaporation method. Different batches containing OAMNP:PLGA ratios(1:4, 1:2 and 3:4) were prepared with ICG (group B-1, 2, 3) and without ICG (group A-1,2, 3) loading. All the formulations were characterized in terms of morphology, particle size,zeta potential, magnetic content, ICG encapsulation efficiency and the spectralproperties of ICG. The optimized formulation showed an encapsulation efficiency of56 ± 4.6% for ICGand 57 ± 1.37% for OAMNP. The biodistribution and brain targeting study involved three groups of six animals, eachwith 0.4 mg kg − 1 equivalent of ICG, given as neat ICG solution, composite nanoparticles without theaid of a magnetic field, and composite nanoparticles under the influence of amagnetic field (8000 G) to groups 1, 2 and 3 respectively. The tissue analysis andmicroscopy images revealed a significantly higher brain concentration of ICG (p < 0.05) for group 3 than the two control groups. These results are encouraging for the braindelivery of hydrophilic dyes/drugs using this method for biomedical applications.