β-N-acetylglucosaminidase grafted on mesoporous silica nanoparticles. A bionanoantibiotic system against Staphylococcus aureus bacteria

A bionanoantibiotic system based on beta-N-acetylglucosaminidase (Ami) and Lysozyme (Lyz) enzymes grafted on the external surface of amino functionalized mesoporous silica nanoparticles, having a radial arrangement of pores (MSNr-NH2), was prepared and fully characterized. Before the enzyme grafting the nanoparticles were also loaded with the antibiotic drug levofloxacin (Levo) to explore the possible synergic effect with the enzymes. MSNr-NH2-Lyz-Levo and MSNr-NH2-Ami-Levo did not show any activity against S. aureus. On the contrary, in the absence of the antibiotic, both Lyz and Ami immobilized on MSNr were able to destroy S. aureus cells, suggesting an inhibiting action of the antibiotic on the enzymes. Although the loading of immobilized Lyz was higher than that of Ami (76 vs. 20 mg/g, respectively), the highest antibacterial efficacy was found for MSNr-NH2-Ami nanoantibiotic. Moreover, MSNr-NH2-Ami was active against S. aureus even at very low concentration (12.5 mu g/ mL) with a bactericidal activity (79%), higher than that determined for MSNr-NH2 loaded with levofloxacin (54%). These results suggest the possibility of using enzyme grafted MSNr as a bionanoantibiotic drug with high efficiency even at low nanoparticles concentration.