Highly specific colloidal ɣ-Fe₂O₃-DNA hybrids: From bioinspired recognition to large-scale lactoferrin purification

The industry transfer of laboratory-use magnetic separation is still hampered by the lack of suitable nanoparticles, both in terms of their features and large-scale availability. Surface Active Maghemite Nanoparticles (SAMNs) characterized by a unique surface chemistry, low environmental impact, scalable synthesis and functionalization were used to develop a bio-inspired lactoferrin (LF) recognition system. Based on the LF affinity for DNA, a self-assembly process was optimized for obtaining a SAMN@DNA hybrid displaying chemical and colloidal stability and LF specificity. SAMN@DNA was successfully tested for the affinity purification of LF from crude bovine whey. Advantages, such as high selectivity and loading capacity, nanoparticle re-usability, outstanding purity (96 ± 1%), preservation of protein conformation and short operational time, were highlighted. Finally, scalability was demonstrated by an automatic system performing continuous purification of LF from 100 liters day^-1 of whey. This study responds to essential prerequisites, such as efficiency, re-usability and industrialization feasibility.