Apoferritin nanocage as streptomycin drug reservoir: Technological optimization of a new drug delivery system

The aim of this study is to formulate and characterize streptomycin-loaded apoferritin nanoparticles (ApoStrep NPs) for their potential therapeutic use in bacterial resistant infections (i.e. tuberculosis). ApoStrep NPs were prepared by disassembly/reassembly process via pH method and changing apoferritin/drug molar ratio, purified by dialyses process also associated with gel filtration chromatography and characterized in their chemico-physical and technological parameters as yield, size distribution, polidispersivity, morphology, internal structure, zeta potential and loading efficacy. The results showed that spherical reproducible NPs could be obtained by using apoferritin/drug molar ratio lower than 1:25 and purification based on the combination of dialysis and gel filtration chromatography. Photon correlation spectroscopy, Uv-visible detection and electron microscopy showed the maintenance of the native apoferritin chemico-physical properties and structure. When formulated with apoferritin/drug 1:10 and 1:25 molar ratio, ApoStrep NPs showed remarkable encapsulation efficacy (35% and 28%, respectively) along with kinetic profile of drug delivery, approximately 15% at 37 °C in 72h, as evidenced by "in vitro" release experiments.