Nanobiotechnological application of magnetic hyperthermia for green microbial cell disruption and carotenoid release

Abstract

Magnetite (Fe₃O₄) nanoparticles are widely explored as heat-generating agents in magnetic hyperthermia, a physical phenomenon in which particles convert electromagnetic energy into localized heat under an alternating magnetic field. This work focused on the synthesis, physicochemical characterization, and heating performance evaluation of magnetite nanoparticles, using their application as a green tool for microbial cell disruption as a case study. Nanoparticles were synthesized by coprecipitation of Fe(II) and Fe(III) chlorides at a stoichiometric ratio of 0.5, followed by an acid post-treatment and washing steps. X-ray diffraction confirmed a single magnetite phase matching the reference pattern (COD No. 900-6247), with a crystallite size of 11.17 nm calculated from the (311) reflection using the Scherrer equation. Dynamic light scattering revealed a monodisperse hydrodynamic size distribution centered at 165 nm, while zeta potential measurements yielded −76.1 mV, indicating high colloidal stability driven by strong electrostatic repulsion between particles. The heating capability of the nanoparticles was then evaluated under an alternating magnetic field at three concentrations (25, 50 and 100 mg/mL) over 30 minutes. All suspensions displayed a concentration-dependent, progressive temperature rise that stabilized after 25 minutes, reaching maximum values of 38, 40 and 50 °C, respectively, consistent with heat generation through Néel and Brownian relaxation and hysteresis losses. As proof of concept, the lowest nanoparticle concentration was applied to induce controlled thermal disruption of Rhodotorula toruloides yeast cells, successfully releasing intracellular carotenoids into the surrounding medium, evidenced by a visible color change and a UV-vis absorbance band near 500 nm. Overall, these results show that the synthesized magnetite nanoparticles combine adequate crystallinity, colloidal stability, and tunable, concentration-controlled heating performance, positioning them as an efficient nanomaterial platform for magnetic hyperthermia applications, extending beyond conventional biomedical uses and representing a promising biotechnological tool for controlled biomass processing and biocompound recovery.

Keywords: nanoparticles; magnetic hyperthermia; microbial cell disruption