Iron oxide nanoparticles: a platform for biomolecule conjugation

Among the nanomaterials, of great interest are iron oxide nanoparticles (IONPs), which possess unique magnetic properties, low toxicity and high biocompatibility. For these reason, IONPs are widely used in industrial and biomedical field. Here, IONPs were synthetized via co-precipitation method, obtaining NPs reproducible in shape and size distribution. First, IONPs were used as a platform for the conjugation of two thermophilic enzymes, L-aspartate oxidase and amylase to obtain an effective biocatalyst. Different binding strategies were studied leading to different enzymatic activity due to the different orientations and stretching of the proteins. Next, the NP-enzyme systems were nanoactuated by an alternate magnetic field (AMF) without increasing the overall temperature of the solution. Remarkably, the nano-systems were successfully reused for at three consecutive cycles of AMF with the loss of the 40% of the initial activity. IONPs were also used developed a nano-antibiotic system, using teicoplanin. The antimicrobial efficacy of NP-TEICO was assessed through classical microbiological methods and morphological studies. Results indicate that teicoplanin conjugation confers high and prolonged antimicrobial activity to IONPs toward Gram-positive bacteria, inhibiting also S. aureus biofilm formation, while no antimicrobial activity was detectable towards Gramnegative. Additionally, conjugation of teicoplanin improved the cytocompatibility of IONPs towards two human cell lines. To conclude, IONPs were successfully synthetized, functionalized and employed as a platform for biomolecules conjugation. Indeed two effective different nano-biocatalysts and a nano-antibiotic were obtained.