Mean-field and linear regime approach to magnetic hyperthermia of core–shell nanoparticles: can tiny nanostructures fight cancer?

Carrião, Marcus S.; Bakuzis, Andris F.

doi:10.1039/c5nr09093h

Cited by 38 publications

(47 citation statements)

References 71 publications

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“…In the present work, we have demonstrated that surface atoms can respond differently than the core ones, a prominent effect for the smaller fully oxidized derivatives (≤12 nm) of the Fe x O − Fe 3−δ O 4 NCs. Although defect elimination during synthesis can yield nanomagnetic agents (≥20 nm) with enhanced, concurrent diagnostic imaging and thermo-responsive performances [34], structural defects at subcritical particle sizes appear to offer a different exploitable pathway, compatible with the biological limits (e.g., set by toxicity and patient discomfort) [67]. Here, vacancies in self-passivated iron oxides of subcritical size (≤12 nm) act as pinning centers that favor the competition of exchange interactions, thus fostering local anisotropy enhancement.…”

Section: Defect-driven Magnetic Heatingmentioning

confidence: 99%

Vacancy-Driven Noncubic Local Structure and Magnetic Anisotropy Tailoring in FexO−Fe3−δO

et al. 2019

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In contrast to bulk materials, nanoscale crystal growth is critically influenced by size-and shape-dependent properties. However, it is challenging to decipher how stoichiometry, in the realm of mixed-valence elements, can act to control physical properties, especially when complex bonding is implicated by short and long-range ordering of structural defects. Here, solution-grown iron-oxide nanocrystals (NCs) of the pilot wüstite system are found to convert into iron-deficient rock-salt and ferro-spinel sub-domains, but attain a surprising tetragonally distorted local structure. Cationic vacancies within chemically uniform NCs are portrayed as the parameter to tweak the underlying properties. These lattice imperfections are shown to produce local exchange-anisotropy fields that reinforce the nanoparticles' magnetization and overcome the influence of finite-size effects. The concept of atomic-scale defect control in subcritical size NCs, aspires to become a pathway to tailor-made properties with improved performance for hyperthermia heating over defect-free NCs. 5 Results 1 Structural insights Single-particle local structureFour nanoparticle samples were made available for this study, with specimen of spherical shape, entailing diameters of 8.1 ± 0.6 nm and 15.4 ± 1.3 nm and of cubic shape, obtaining edge-lengths of 12.3 ± 0.7 nm and 17.7 ± 1.6 nm ( Fig. S1). Henceforth, these are called S8, S15, C12 and C18, where 'S' stands for spherical and 'C' for cubic morphologies. Moreover, high-resolution transmission electron microscopy (HRTEM) ( Fig. 2a-d) suggests that the smaller S8 and C12 NPs entail a domain of a single-phase material, but the bimodal contrast in the larger S15 and C18 points that above a particle size of 12 nm two nanodomains are attained. The coexistence of dark and light contrast features in the S15 and C18 could be justified assuming that two chemical phases, of varying electron diffracting power, share the same nanoparticle volume. Crystallographic image processing by Fast Fourier transform (FFT) analysis of the relevant HRTEM images results in their corresponding (spot) electron diffraction patterns ( Fig. 2e-h). The unequivocal indexing of reflections in the S8 and C12 specimen may suggest that these adopt the magnetite type of phase ( Fig. 2e, f). On the other hand, a similar conclusion cannot be made after the evaluation of the FFT patterns of the apparently bimodal contrast S15 and C18 specimen as the cubic spinel and rock salt reflections (Fig. 2g, h) appear to be resolution limited. The behavior appears in line with the tendency of bulk wüstite for oxidative conversion, [28], [42] and infers a process analogous to its elimination from 23 nm core@shell FexO@Fe3-δO4 nanoparticles. [25] The long and short-range modulations of the selected (hkl) atomic planes could become more easily isolated with direct space images derived from the inverse FFT synthesis of chosen families of reflections. We find that the (400) (or (200) for the core@shell S15 and C18 NPs) family generates perfect atomic...

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Section: Defect-driven Magnetic Heatingmentioning

confidence: 99%

Vacancy-Driven Noncubic Local Structure and Magnetic Anisotropy Tailoring in FexO−Fe3−δO

et al. 2019

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“…In general, it was shown both in simulations and experiment that complex nanoparticles with ferromagnetic core and ferrimagnetic shell morphology can enhance the efficiency of hyperthermia 70 . Another combined theoretical-experimental investigation of the hyperthermia was recently carried out on the level of mean-field for the model core-shell particle 71 . Unfortunately, these approaches cannot be directly applied to predict or analyse the dynamic spectra of magnetic dipolar nanoparticle systems, as they lack an intrinsic feature of the latter, namely, particle polydispersity.…”

Section: Introductionmentioning

confidence: 99%

Temperature-dependent dynamic correlations in suspensions of magnetic nanoparticles in a broad range of concentrations: a combined experimental and theoretical study

Иванов

Kantorovich

Zverev

et al. 2016

Phys. Chem. Chem. Phys.

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The interweave of competing individual relaxations influenced by the presence of temperature and concentration dependent correlations is an intrinsic feature of superparamagnetic nanoparticle suspensions. This unique combination gives rise to multiple applications of such suspensions in medicine, nanotechnology and microfluidics. Here, using theory and experiment, we investigate dynamic magnetic susceptibility in a broad range of temperatures and frequencies. Our approach allows, for the first time to our knowledge, to separate clearly the effects of superparamagnetic particle polydispersity and interparticle magnetic interactions on the dynamic spectra of these systems. In this way, we not only provide a theoretical model that can predict well the dynamic response of magnetic nanoparticles systems, but also deepen the understanding of the dynamic nanoparticle self-assembly, opening new perspectives in tuning and controlling the magnetic behaviour of such systems in AC fields.

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“…Em geral, esse monitoramento é realizado com a Ressonância Magnética (RM) [3], que é uma técnica cara. Entretanto, tal procedimento não pode ser utilizado no caso da hipertermia magnética com nanopartículas [4][5][6][7][8][9][10], já que esta nanoterapia depende da rotação dos momentos magnéticos das nanopartículas sob ação de campo alternado. Logo, neste caso, não há como ter geração de calor pois o campo magnético de alta intensidade do ímã permanente da RM impossibilita a rotação dos momentos magnéticos das nanopartículas.…”

Section: Introductionunclassified

“…Assim, métodos baseados em sistema de processamento de sinais, simples e de baixo custo, como o sistema de imagens por ultrassom, torna-se uma alternativa interessante. Note, adicionalmente, que o ultrassom pode ser capaz de fornecer uma estimativa de temperatura interna em tempo quase real e ser combinada com várias nanoterapias térmicas, como a hipertermia magnética [4][5][6][7][8][9][10] ou a fototérmica [11].…”

Section: Introductionunclassified

Ultrassom Diagnóstico Como Técnica Para a Estimativa Não Invasiva de Temperatura Visando Nanoterapias Térmicas

Faria¹,

Gonalves²,

Capistrano³

et al. 2018

Anais Do v Congresso Brasileiro De Eletromiografia E Cinesiologia E X Simpósio De Engenharia Biomédica

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Resumo: A medicina térmica trata do uso clínico da distribuição seletiva de calor para o tratamento de doenças, em particular câncer. Esta terapia foi recentemente utilizada como coadjuvante porque apresenta sinergia em radioterapia e quimioterapia. Dentre os problemas mais importantes esta o monitoramento não invasivo da distribuição de calor. A técnica tradicional é a ressonância magnética nuclear, que é dispendiosa e não pode ser utilizada em hipertermia magnética com nanopartículas. Assim, a estimativa de temperatura não invasiva usando ultrassom de eco-pulso se apresenta como uma excelente alternativa. A metodologia deste trabalho baseia-se na medição do deslocamento de estruturas internas em imagens de ultrassom em função da temperatura, para amostras de tecido biológico de suíno, que foram submetidas ao aumento de temperatura em um banho de água, enquanto analisadas pelo método de ultrassom de pulso-eco, obtido por meio de um equipamento de ultrassom clínico ordinário, para formar as imagens a diferentes temperaturas, na faixa de 37,0 ° C a 50,0 ° C, com intervalos de variação de 0,5 ° C ± 0,1 ° C. Por meio de um algoritmo de correlação bidimensional, com o auxílio de um software para processamento de imagens, foi possível calcular os deslocamentos das regiões características das imagens das amostras em função da temperatura. Os resultados preliminares mostram que é possível relacionar a variação de temperatura com o deslocamento da amostra nesta condição, e sugerem que esta técnica pode ser usada para monitorar a temperatura interna dos tecidos in vivo para aplicações em hipertermia magnética ou terapia fototérmica.Palavras-chave Deslocamento aparente, Estimativa não invasiva de temperatura, Ultrassom pulso-eco.Abstract: Thermal medicine deals with the clinical use of selective heat delivery for the treatment of diseases, in particular cancer. This therapy has recently been used as a coadjuvant because it presents synergy in radiotherapy and chemotherapy. Among the most important problems is the non-invasive monitoring of heat delivery. The traditional technique is nuclear magnetic resonance, which is expensive, and cannot be used in magnetic hyperthermia with nanoparticles. Thus, the non-invasive temperature estimation using pulse-echo ultrasound presents itself as an excellent alternative. The methodology of this work is based on measuring the displacement of internal structures in ultrasound images as a function of temperature, for samples of biological swine tissue, which were submitted to temperature increase in a water bath, while analyzed by the pulse-echo ultrasound method, obtained by means of an ordinary clinical ultrasound equipment, in order to form the images at different temperatures, in the range of 37.0 ° C to 50.0 ° C, with intervals of variation of 0.5 ° C ± 0.1 ° C. By means of a twodimensional correlation algorithm, with the aid of a software for image processing, it was possible to calculate the displacements of the characteristic regions of the images of the samples as a function of...

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Mean-field and linear regime approach to magnetic hyperthermia of core–shell nanoparticles: can tiny nanostructures fight cancer?

Cited by 38 publications

References 71 publications

Vacancy-Driven Noncubic Local Structure and Magnetic Anisotropy Tailoring in FexO−Fe3−δO

Vacancy-Driven Noncubic Local Structure and Magnetic Anisotropy Tailoring in FexO−Fe3−δO

Temperature-dependent dynamic correlations in suspensions of magnetic nanoparticles in a broad range of concentrations: a combined experimental and theoretical study

Ultrassom Diagnóstico Como Técnica Para a Estimativa Não Invasiva de Temperatura Visando Nanoterapias Térmicas

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