Alternating magnetic field and NIR energy conversion on magneto-plasmonic Fe3O4@APTES-Ag heterostructures with SERS detection capability and antimicrobial activity

Multipurpose Fe3O4@APTES-Ag heterostructures for mutual heat generation, SERS probing, and antimicrobial activity were fabricated using a three-step process. Silver metallic particles were precipitated on a thin silica shell that served as an interlayer with Fe3O4 nanocubes. The structural properties were studied by means of the powder X-ray diffraction technique, and selected area electron diffraction. Particle size, distribution, and morphology were evaluated using transmission electron microscopy, while element mapping was performed using the STEM-EDS technique. The presence of the silica shell and the effectiveness of the Ag reduction were checked by FTIR-ATR spectroscopy. The heat generation ability was studied by using AMF and NIR contactless external stimulations working separately and simultaneously. We demonstrated that the dual mode stimulation leads to a SAR (specific absorption rate) of 1000 W g(-1) with the predominant role of the mechanism associated with the light interaction. The SERS effect was recorded with the use of the R6G standard molecule showing high capability of the heterostructures for Raman signal augmentation. Fe3O4 nanocubes decorated with Ag particles have shown antibacterial activity against P. aeruginosa. The Fe3O4@APTES-Ag presents promising potential as a multipurpose platform for biological applications ranging from photomagnetic therapies, to analytical probes exploiting the SERS effect and antibacterial activity.