Spray-Dried Hierarchical Aggregates of Iron Oxide Nanoparticles andTheir Functionalization for Downstream Processing in Biotechnology

摘要

In this work, the structuring of iron oxide nanoparticles via spray-drying (SD) of aqueous suspensions is investigated, leading to micrometer-sized aggregates with saturation magnetization comparable to that of the individual nanoparticles. Interestingly, the superparamagnetic behavior is retained despite the multicore structure. Modification of the aggregates via the addition of silica nanoparticles to the suspension allows for control of the resulting magnetization by adjusting the iron oxide content. Moreover, the morphology of the produced aggregates is gradually shifted from irregular inflated-like shapes in case of pure iron oxide aggregates to reach spherical structures when bringing the silica content to only 20%. The aggregates with different magnetization can be effectively separated in a simple column with an attached permanent magnet. Functionalization of pure iron oxide aggregates with a previously coupled ligand holding a nitrilotriacetic acid (NTA)-like moiety and subsequent loading with Ni²⁺ ions leads to the ability to bind 6-histidine (His6)-tagged target proteins via chelation complexes for magnetic separation. The application of the presented system for the purificationof recombinant protein A in multiple cycles is shown. The recyclabilityof the separation system in combination with the high degree of magneticseparation is promising for future applications in the field of preparativein situ protein purification.