Magnetic MnFe2O4 Core–shell nanoparticles coated with antibiotics for the ablation of pathogens

Emerging β-lactam antibiotic resistance necessitates the development of new therapeutic approaches. One approach to counteract this issue is the use of nanoparticles (NPs) for antimicrobial agent delivery. In this work, superparamagnetic MnFe 2 O 4 NPs were synthesized via a simple co-precipitation method followed by coating with a SiO 2 shell using tetraethoxysilane (TEOS) to prevent agglomeration and also increase the density of hydroxyl groups on the surface of MnFe 2 O 4 NPs. The resulting MnFe 2 O 4 @SiO 2 nanostructures were further functionalized with 3-aminopropyltriethoxysilane (APTES) to introduce NH 2 groups on the surface of NPs for covalent grafting of ampicillin (AMP), β-lactam antibiotic. The MnFe 2 O 4 @AMP NPs proved to be highly effective for the eradication of Escherichia coli bacteria with a minimum inhibitory concentration (MIC) equivalent to 4 µg/mL of immobilized AMP, lowered by 50% compared to free AMP. The intrinsic multivalence effect of the nanostructures as well as the protection of the COO − group of the antibiotic from the attack of β-lactamase enzyme is believed to be responsible for enhanced efficiency of the hybrid compared to free AMP. Graphic abstract