Structure, magnetism and heating ability of pyrrole-functionalized magnetic biochar (PFMB) for magnetic hyperthermia

Abstract

This work reports the synthesis, characterization, and magnetic hyperthermia performance of pyrrole-functionalized magnetic biochar (PFMB) nanocomposites prepared via a hydrothermal method. The PFMB system comprises Fe₃O₄ nanoparticles embedded in a biochar matrix and coated with pyrrole to improve colloidal stability and heating efficiency. Structural and morphological analyses (XRD, FTIR, SEM/EDAX) confirmed the formation of a magnetite phase and successful surface functionalization. Magnetic measurements reveal a transition from ferrimagnetic behavior in bare MB to superparamagnetism in PFMB, with saturation magnetization reduced significantly from 58.8 to 20.8 emu g⁻¹. Magnetic hyperthermia experiments under alternating magnetic fields (AMF) manifest enhanced heating efficiency for PFMB, with sample absorption rate (SAR) values varying considerably from 24.27 to 53.77 W g⁻¹, compared to 12.34–31.80 W g⁻¹ for MB. The results indicate that at higher frequencies (332 kHz and 469 kHz), both MNPs reach the therapeutic hyperthermia threshold of 42 °C in a relatively short time. The heating performance correlates well with both frequency and field amplitude. Intrinsic loss power (ILP) values for PFMB reach 0.70 nH m² kg⁻¹, aligning with the values reported for established polymer-coated MNPs. These results demonstrate the potential of PFMB nanocomposites as efficient and stable candidates for in vitro magnetic hyperthermia applications.