Photothermal effects and toxicity of Fe₃O₄ nanoparticles via near infrared laser irradiation for cancer therapy

The photothermal effect of magnetite (Fe₃O₄) nanoparticles was characterized by photonic absorption in the near-infrared (NIR) region. Upon laser irradiation at 785 nm, the Fe₃O₄ nanoparticles generate localized hyperthermia in tumorous lesions, which is an effective strategy for cancer therapy; however, uncoated magnetite possesses an innate toxicity which can lead to drawbacks in the clinical setting. To reduce innate toxicity, a poly(acrylic acid) (PAA) coating on the nanoparticles was investigated in order to determine the alterations to stability and the degree of toxicity in an attempt to create a higher utility vector. It was found that the PAA coating significantly reduced the innate toxicity of the uncoated magnetite. Furthermore, the efficacy of PAA-coated magnetite nanoparticles (PAA-Fe₃O₄) was investigated for treating MDA-MB-231 (human mammary gland adenocarcinoma) cultures in viable concentration ranges (0.1–0.5 mg/ml). An appropriate PAA-Fe₃O₄ concentration range was then established for inducing significant cell death by hyperthermic ablation, but not through innate toxicity. - Highlights: • Uncoated magnetite NPs possess high innate toxicity in MDA-MB-231 cultures. • PAA coating significantly reduces innate toxicity and stabilizes magnetite NPs. • Thermal ablation begins at 0.2 mg/ml for PAA-Fe₃O₄ at 785 nm NIR laser, 38.5 kW/m². • 38.5 kW/m² does not significantly affect MDA-MB-231 viability in-vitro