Fabrication of monodisperse magnetic nanorods for improving hyperthermia efficacy

Shan Zhao,P Jack Hoopes,John X J Zhang,Nanjing Hao,Fridon Shubitidze,Zi Chen

doi:10.1186/s12951-021-00794-8

Abstract

BackgroundHyperthermia is one of the promising cancer treatment strategies enabled by local heating with the use of tumor-targeting magnetic nanoparticles (MNP) under a non-invasive magnetic field. However, one of the remaining challenges is how to achieve therapeutic levels of heat (without causing damages to regular tissues) in tumors that cannot be effectively treated with anti-tumor drug delivery.ResultsIn this work, we report a facile method to fabricate magnetic nanorods for hyperthermia by one-step wet chemistry synthesis using 3-Aminopropyltrimethoxysilane (APTMS) as the shape-controlling agent and ferric and ferrous ions as precursors. By adjusting the concentration of APTMS, hydrothermal reaction time, ratios of ferric to ferrous ions, magnetic nanorods with aspect ratios ranging from 4.4 to 7.6 have been produced. At the clinically recommended field strength of 300 Oe (or less) and the frequency of 184 kHz, the specific absorption rate (SAR) of these nanorods is approximately 50 % higher than that of commercial Bionized NanoFerrite particles.ConclusionsThis increase in SAR, especially at low field strengths, is crucial for treating deep tumors, such as pancreatic and rectal cancers, by avoiding the generation of harmful eddy current heating in normal tissues.

Highlights

Hyperthermia is one of the promising cancer treatment strategies enabled by local heating with the use of tumor-targeting magnetic nanoparticles (MNP) under a non-invasive magnetic field
Hyperthermia can be induced in tumor tissue by embedding magnetic nanoparticles and activating them with an alternating magnetic field and cell death can occur when a sufficient cumulative effective heat dose is reached [1,2,3,4]
These results clearly suggest that the aspect ratio of the nanorods plays an important role in their heating efficiency

Summary

Introduction

Hyperthermia is one of the promising cancer treatment strategies enabled by local heating with the use of tumor-targeting magnetic nanoparticles (MNP) under a non-invasive magnetic field. Hyperthermia can be induced in tumor tissue by embedding magnetic nanoparticles and activating them with an alternating magnetic field and cell death can occur when a sufficient cumulative effective heat dose is reached [1,2,3,4]. The treatment can be targeted to the tumor area by accurate placement of the nanoparticles and targeting the activating magnetic field [5, 6]. 1D iron oxide materials, such as nanorods, nanotubes, nanowires and nanobelts, are found to have potential applications in medical, electrical, magnetic and optical nanodevices [21]. The most common iron oxide crystallites include hematite (α-Fe2O3), maghemite (γ-Fe2O3), goethite (α-FeOOH), akageneite (β-FeOOH or ClFeOOH), and magnetite (Fe3O4)

Methods

Results

Discussion

Conclusion