Bioconjugated Magnetic Nanoparticles for Rapid Capture of Gram-positive Bacteria

In this paper, bioconjugated Magnetic Nanoparticles (MNPs) are developed for rapid capture gram-positive bacterium Staphyloccocus aureus (S. aureus). The MNPs was synthesized through a two-step sol-gel process, followed a bioconjugation of gentamicin (Gm), an aminoglycoside antibiotic, via the linker, glutaraldehyde. The average diameter of the magnetic core is 18 ± 3 nm and the thickness of shell is around 5 ± 3 nm. The XRD results indicate that core-shell MNPs consist of magnetic core, Fe3O4, and silica (SiO2) shell. In addition, the core-shell MNPs show the ferromagnetic properties, whereas the monodipersed Iron Oxide Magnetic Nanoparticles (IONPs), which were produced in the first step, show the typical superparamagnetic properties with a blocking temperature (TB) at 115 K. The interactions between S. aureus and core-shell MNPs with and without Gm have been further investigated by using a Transmission Electron Microscopy (TEM). Our results demonstrate that the diluted S. aureus with the concentration as low as 0.5 ×103 CFU/mL can be separated from the solution by the core-shell MNPs in one minute.