The Effect of Various Surface Functionalizations of Core-Shell Nanoactuators on Magnetoelectrically Driven Cell...

Magnetoelectric (ME) nanoparticles (NPs) exhibit strong coupling between magnetic and electric properties, enabling wireless control of biological processes through electromagnetic stimulation, which paves the way for diverse biomedical applications. However, the surface functionalization of ME NPs and its impact on their structure, physical properties, and biological response remain largely unexplored. In this study, biocompatible citric acid (CA) and pectin (PEC) were employed to functionalize quasi-spherical ME core-shell NPs comprising a magnetic spinel MnFe₂O₄ core (∼23 nm) and a ferroelectric perovskite Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃ (BCZT) shell (∼5 nm), synthesized using microwave-assisted hydrothermal processing. The surface functionalization led to the formation of covalent bonds between CA and metal ions of NPs via chelation. The surface functionalization with PEC increased ζ-potential values of ME NPs up to -46.2 ± 0.6 mV compared to CA (25.3 ± 1.0 mV). Both MFO@BCZT NPs with CA and PEC exhibited low coercivity values (69 ± 5 and 29 ± 2 Oe, respectively) with a pronounced specific saturation magnetization (6.1 ± 0.2 and 5.2 ± 0.2 emu/g, respectively). No effect of the BCZT shell with subsequent CA (746 ± 22 Oe) and PEC (754 ± 23 Oe) surface functionalizations on the anisotropy field of ME NPs was observed compared to the pristine MFO cores (754 ± 23 Oe). Both CA-/PEC-functionalized MFO@BCZT NPs exhibited ferroelectric behavior with robust piezoresponse (9.95 ± 1.36 and 10.24 ± 2.03 pm/V, respectively) and high ME response (81 × 10⁴ and 80 × 10⁴ mV·cm^-1·Oe^-1, respectively), comparable to the most frequently studied Co-based analogs. In vitro assays demonstrated the ability of the developed ME NPs to control calcium flux, which enables bidirectional regulation of cell proliferation. This work advances the development of efficient and biocompatible ME NPs with promising applications in the noninvasive and targeted stimulation of cell behavior.