Addressing the dynamical magnetic response of magnetic nanoparticles after interacting with biological entities

Resumen

Heat dissipation due to hysteresis losses in magnetic materials generally constitutes a difficult issue to circumvent. But in magnetic nanoparticles (MNPs) instead, their ability to release heat when subjected to external alternating magnetic fields (AMF) is currently being exploited for treating solid tumors in the so-called magnetic hyperthermia (MH) therapy. In those therapies, the preservation of the MNPs magnetic response after interacting with biological entities (biomolecules, cells and/or tissues) and their related heat dissipation is crucial for their use in biomedical applications. However, recent studies point out that the interactions of MNPs with cells, tissues or proteins strongly modifies their intrinsic magnetic properties. Among the underlying reasons behind such variation of magnetic properties of IONPs, enhancement of environmental viscosity, IONPs clustering and protein adsorption are pointed as the main causes. Here, we evaluated the dynamical magnetic response of a wide set of MNP under biological-mimicking and directly when they interact with live cells and biomolecules. In biological-mimicking medium, we examined on one hand the impact of inter and intra-aggregate magnetic dipolar interactions on the MNPs magnetic response, observing different phenomena related to both types of magnetic dipolar interactions. On the other hand, we evaluated the role of the environmental viscosity on the dynamical magnetic response of MNPs colloids. Later, we investigated how the interaction of MNPs with live cells and biomolecules affects the MNPs nanomagnetism. First, we investigated the influence of IONP cell internalization on their dynamical magnetic response by AC magnetometry and susceptometry, finding that intracellular MNPs clustering provides the major contribution to the changes of the studied MNPs magnetic response. Finally, we assessed the effects of dispersing MNPs in biological fluids on their magnetic response, demonstrating the ability of AC magnetometry to unveil unspecific and specific MNPs-biomolecule interaction. The know-how outcome of this thesis work will allow the design of novel nanostructures whose magnetic losses (i.e. magnetic hyperthermia efficiency) will remain non-influenced by viscosity and aggregation effects related to biological environments. Moreover, our findings encourage further investigation towards the engineering of more complex functionalized MNPs which, ultimately, will allow conception of an effective biomarkers sensing platform based on the use of AC magnetometer.