Alternating magnetic field and NIR energy conversion on magneto-plasmonic Fe₃O₄@APTES-Ag heterostructures with SERS...

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.