Síntese e caracterização de nanopartículas magnéticas de ferrita de cobalto (CoFe2O4)

Abstract

Cobalt ferrite (CoFe2O4) magnetic nanoparticles (MNPs) attract significant interest in biomedical applications due to their unique magnetic properties. However, their synthesis and stabilization are challenging. This study aimed to establish a robust protocol for the synthesis of CoFe2O4 MNPs by the chemical coprecipitation method and their characterization by AC Biosusceptometry (ACB) and Dynamic Light Scattering (DLS). The study focused on protocol optimization, comparing preliminary results with those from an optimized process. Preliminary results showed a near-zero magnetic response (ACB average signal of 0.027 mV) and colloidal instability (DLS), with macroscopic aggregates (R ≈ 1380 nm). After refining the protocol, focusing on rigorous washing and precise final pH control (8.85), the optimized sample exhibited a magnetic response three orders of magnitude higher (stable signal of 56.6 mV). The optimized DLS analysis revealed the elimination of macroscopic aggregates and a controlled bimodal distribution, composed of a primary population (R ≈ 6.9 nm, 80.6% mass) and a minority population of small aggregates (R ≈ 52.8 nm, 19.4% mass). It was concluded that rigor in the washing process and pH control is critical to overcoming the strong magnetic attractive interactions of cobalt ferrite, enabling sample stabilization. The optimized protocol produced a material with promising characteristics for future research in magnetic hyperthermia.