Solvothermal synthesis of CuFe2O4 and Fe3O4 nanoparticles with high heating efficiency for magnetic hyperthermia application

Journal Pre-proof Solvothermal synthesis of CuFe2O4 and Fe3O4 nanoparticles with high heating efficiency for magnetic hyperthermia application Seyedeh Maryam Fotukian, Aboulfazl Barati, Meysam Soleymani, Ali Mohammad Alizadeh PII:

S0925-8388(19)33794-6

DOI:

https://doi.org/10.1016/j.jallcom.2019.152548

Reference:

JALCOM 152548

To appear in:

Journal of Alloys and Compounds

Received Date: 19 June 2019 Revised Date:

7 September 2019

Accepted Date: 2 October 2019

Please cite this article as: S.M. Fotukian, A. Barati, M. Soleymani, A.M. Alizadeh, Solvothermal synthesis of CuFe2O4 and Fe3O4 nanoparticles with high heating efficiency for magnetic hyperthermia application, Journal of Alloys and Compounds (2019), doi: https://doi.org/10.1016/j.jallcom.2019.152548. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Elsevier B.V. All rights reserved.

Solvothermal synthesis of CuFe2O4 and Fe3O4 nanoparticles with high heating efficiency for magnetic hyperthermia application Seyedeh Maryam Fotukian1, Aboulfazl Barati1,*, Meysam Soleymani1, Ali Mohammad Alizadeh2 1

Chemical Engineering Department, Faculty of Engineering, Arak University, Arak, Iran 2

Cancer Research Center, Tehran University of Medical Sciences, Tehran, Iran * Email of Corresponding Author: [email protected]

Abstract Magnetic nanoparticles with improved heating efficiency are required for an efficient magnetic hyperthermia therapy. In this study, monodisperse CuFe2O4 nanoparticles (NPs) with higher heat generation capability compared to Fe3O4 NPs were synthesized by a solvothermal method using triethylene glycol as solvent, reductant, and stabilizer. X-ray diffraction (XRD) analysis confirmed the single phase formation of CuFe2O4 and Fe3O4 NPs under experimental conditions. Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of TREG molecules on the surface of both samples. Nanoparticles with spherical shape were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) with an average particle size of 19.9 and 18.5 nm for CuFe2O4 and Fe3O4 NPs, respectively. The room temperature magnetic measurements indicated that both samples are in the vicinity of transition point from superparamagnetic to single-domain ferromagnetic state with a saturation magnetization of 53.1

and 58.8 emu/g for CuFe2O4 and Fe3O4 NPs, respectively. Moreover, CuFe2O4 NPs showed the lower anisotropy energy compared to Fe3O4 NPs, leading to the faster approach to saturation and slightly more rectangular hysteresis loop. The heating efficacy of the CuFe2O4 and Fe3O4 NPs were investigated under different safe alternating magnetic fields permissible for magnetic hyperthermia therapy (f=120 kHz, H=13, 16, and 19 kA/m). The maximum specific absorption rate (SAR) obtained for CuFe2O4 and Fe3O4 NPs were 44.9 and 18.5 W/g, respectively, at magnetic field intensity of 19 kA/m and frequency of 120 kHz. The two-fold increase in the SAR value of the CuFe2O4 NPs compared to the Fe3O4 NPs might be attributed to the tuning and better matching of their anisotropy energy with frequency and magnetic field intensity used in magnetic hyperthermia experiments. Keywords: Copper ferrite, Iron oxide nanoparticles, Solvothermal, Magnetic hyperthermia. 1

2

1. Introduction

Magnetic fluid hyperthermia (MFH) is a kind of cancer therapy that magnetic nanoparticles (MNPs) are introduced into the tumor tissue and then exposed to an external alternating magnetic field which results in heat generation by MNPs. The generated heat rises the temperature of the tumor tissue, leading to the damage or death of the cancer cells with minimal side effect on the healthy tissues [1, 2]. The first study into the application of MNPs for hyperthermia therapy was conducted in 1957 by Gilchrist et al. [3]. The induction heating efficiency of MNPs is measured in term of specific absorption rate (SAR). This factor is crucial for clinical applications of MNPs and must be maximized because the higher SAR value leads to the smaller dose of nanoparticles that must be injected inside the body of patient as well as the less exposure time of the process. Many researchers have extensively investigated the effects of particle size, shape, composition, and surface modification of magnetic nanoparticles on the SAR value [4-8]. Among the magnetic nanoparticles, magnetite (Fe3O4) is the most commonly material used in magnetic hyperthermia experiments due to their low toxicity and easy synthesis [9, 10]. Among the doped magnetite nanoparticles, ZnFe2O4 and MnFe2O4 have also been considered because of their high saturation magnetization (Ms) and chemical stability in physiological medium [11, 12]. Magnetic materials with very high Ms are typically metallic and encountered to low chemical stability and high toxicity in physiological medium [13]. An alternative approach to improve the SAR value is increasing the effective anisotropy of the magnetic materials. For instance, iron oxide nanocubes with high shape anisotropy have shown higher SAR value compared to iron oxide nanospheres [14]. Moreover, in some state-of-the-art studies, very large SAR values have been achieved by exchange coupling between hard and soft magnetic phases in magnetic nanoparticles with coreshell structure [12, 13]. However, the high SAR value in such compositions is achieved only at high magnetic field intensities and frequencies impermissible for clinical applications. For clinical hyperthermia applications, there are two limitations for the product of the amplitude (H) and the frequency (f) of the applied magnetic field which known as the Atkinson−Brezovich limit (H×f = 4.85×108 Am-1s-1) and the Hergt's limit (H×f = 5×109 Am-1s-1) [15, 16]. When the frequency of the magnetic field is fixed at 100 kHz (a typical value used in the clinical hyperthermia treatment [17, 18]) H will be between 4.85 kAm−1 (60 Oe, according to the 3

Atkinson−Brezovich limit) and 50 kAm−1 (625 Oe, according to the Hergt's limit). Also, in our previous in vivo study, an alternating magnetic field with amplitude about 4 kAm−1(50 Oe) and frequency of 120 kHz (H×f= 4.8×108 Am-1s-1) did not show adverse effects on animal body during the hyperthermia experiments [19]. Since the anisotropy field of Fe3O4 nanoparticles is larger than the field amplitude used in the magnetic hyperthermia therapy, alloying with a soft material can reduce the anisotropy energy barrier for magnetization reversal, leading to a MNPs with higher SAR value [8]. Several methods have been introduced to synthesize magnetic nanoparticles including coprecipitation, Sol-Gel, reverse microemulsion, polyol and thermal decomposition methods [10, 20-22]. Among the preparation methods, polyol method is a very promising technique since the particles prepared by this procedure are pure, monodisperse, and uniform with narrow size distribution [22]. In this method, thermal decomposition of metal salts occurs in a high-boiling solvent such as poly-(vinyl alcohol),ethylene glycol, tri-, tetra-, or poly-(ethylene glycol) [22, 23]. In the polyol method, the solvent plays three major roles including a solvent, a surfactant, and a reducing agent. The solvent specifies the morphology and size of the resulting particles through reduction of the metal complexes to unstable metal nuclei, which consequently convert to metal nanoparticles. Cai et al. have successfully synthesized iron oxide nanoparticles by polyol method and they examined the effect of several solvents (e.g. ethylene glycol, di-, tri-, and tetra-ethylene glycol) for reducing Fe(acac)3 to magnetite nanoparticles [22]. They observed that only the reaction of Fe(acac)3 in triethylene glycol results in monodisperse Fe3O4 nanoparticles. Most experimental studies focused on the synthesizing of magnetic nanoparticles using polyol method are performed in a conventional set-up consisting of a round bottom flask equipped with a condenser and magnetic stirrer. The magnetic nanoparticles obtained using the conventional set-up usually are in the superparamgnetic regime with very low hysteresis loss. As, The SAR value of the magnetic nanoparticles is directly related to their hysteresis loss and consequently to their AC hysteresis loop area, so magnetic nanoparticles with bigger AC hysteresis loop area under a certain applied magnetic field will display a better heating efficiency [24]. In this study, we aim to prepare monodisperse CuFe2O4 and Fe3O4 NPs using a solvothermal method as heat sources for magnetic hyperthermia therapy. One of the main advantages of the employed method for the preparation of CuFe2O4 NPs is the preparation of nanoparticles with elimination of high temperature calcination step that could lead to the formation of monodisperse 4

nanoparticles with no agglomeration. On the other hand, the substitution of Fe by Cu ions in the CuFe2O4 NPs allows us to obtain particles with lower magnetic anisotropy which could produce higher SAR value under the safe clinical magnetic field. To the best of our knowledge, this is the first report on the solvothermal synthesis of monodisperse CuFe2O4 NPs with an average particle size of below 50 nm.

2. Materials and methods 2.1 Chemicals Iron (III) acetylacetonate (Fe(acac)3, 99.9%), Copper acetylacetonate (Cu(acac)2, 97.0%), Ethyl acetate, ethanol, acetone, and triethylene glycol (TREG) (99%) were purchased from Merck Company and were used as received.

2.2 CuFe2O4 and Fe3O4 nanoparticle synthesis A solvothermal method was implemented to prepare CuFe2O4 and Fe3O4 NPs. For the synthesis of Fe3O4 NPs, 4 mmol of Fe(acac)3 and 40 ml of triethylene glycol were mixed in a 200 ml round bottom flask connected to a reflux condenser. To homogenize the solution, the temperature was increased to 100°C and maintained at this temperature for 1 h. Afterwards the obtained homogenous solution was transferred to a Teflon lined autoclave (75 ml capacity) and then placed in a furnace at 260 °C for 24 h. Next, the mixture was left to cool down to room temperature, which resulted in a black homogeneous dispersion containing magnetite nanoparticles. The obtained product was washed with acetone several times using centrifugation. Then, the nanoparticles were put to dry in an oven at 50°C for 12 h. For the synthesis of CuFe2O4 NPs, the same procedure was employed except that the stoichiometric amount of Cu(acac)2 was added to the triethylene glycol at the first of synthesis process. Briefly, the synthesis process is schematically shown in Fig.1.

5

Fig 1. A schematic diagram of the synthesis method

2.3 Characterization The shape, morphology, and particle size of the prepared nanoparticles were estimated using scanning electron microscopy (SEM, ZEISS, SIGMA VP) and transmission electron microscopy (TEM, Philips-CM120). FTIR spectra were recorded in transmission mode using an ALPHA II FTIR Spectrometer by Bruker Optik GmbH. The crystalline structure of the samples was investigated by X-ray diffraction (XRD) analysis using an X’PertPro diffractometer instrument (Holland) with CuKα radiation (λ=1.54 angstrom). Magnetic properties of the products were studied by vibrating sample magnetometer (VSM; Lake Shore Cryotronics, Model 7407) at room temperature.

2.4 Magnetic Hyperthermia Analysis The heating efficiency of the prepared samples was measured using ahome-made induction heating unit equipped with an 8-turn coil of radius 2 cm. To this end, one ml of magnetic fluid with nanoparticle concentration of 1.5 wt% (15 mg/mL) was inserted into an insulated micro tube and then placed at the center of induction coil. After applying a certain magnetic field, the temperature rise in the sample was recorded with an alcohol thermometer within the specified intervals time. The following equation was used to determine the specific absorption rate (SAR) of sample[25]: 6

⁄

=

⁄

(1)

Where Csuspension and XNP are the specific heat capacity of the magnetic fluid and the weight fraction of the nanoparticles in the magnetic fluid, respectively. Also, (

⁄ ) is the initial slope

of the temperature curve versus time. To evaluate the intrinsic heat induction capability of the magnetic fluids, independent of magnetic field intensity and frequency, the intrinsic loss power (ILP) value of ferrofluid was determined using the following equation [25]: !" #

=

⁄$ ×

"

(2)

Where f and H are the frequency and the intensity of the applied magnetic field, respectively.

3. Result and discussion Magnetite nanoparticles can be prepared by the different types of chemical methods [10, 20-22]. Without any surface modifications, they are not stable in physiological medium and can readily aggregate. Therefore, the surface of nanoparticles should be modified with a suitable coating to enhance the stability of nanoparticles and minimize their aggregation. In this study, we synthesized the TREG-coated CuFe2O4 and Fe3O4 NPs by a one-pot solvothermal method to prepare monodisperse nanoparticles with high crystallinity and uniformity. XRD analysis was used to study the crystal structure of the prepared samples. The XRD patterns of the CuFe2O4 and Fe3O4 NPs are shown in Fig. 2. All diffraction peaks in both samples can be exclusively referred to the CuFe2O4 (JCPDS Card No.: 77-0010), and Fe3O4 (JCPDS Card No.: 75-0449) crystal structures and the presence of any impurities was not detected in our samples, indicating the high purity and crystallinity of the prepared samples. Moreover, by doping Cu in the Fe3O4 crystal structure a peak shift has occurred toward smaller angles, indicating the increase in the distances between planes (311) and lattice constant. This is mainly due to the large copper ionic radius (140 pm) compared to that of iron (64 pm) which is predicted to expand crystal lattice. Also, the mean crystallite size of both products was determined by the DebyeScherrer’s equation [26]:

7

& = 0.9*⁄+,-./

(3)

Where λ is the incident X-ray wavelength with copper source (λ=1.5443 Å), θ is diffraction angle of the peak with maximum height, and β represents the full width at half maximum (FWHM). The mean crystallite sizes of CuFe2O4 and Fe3O4 NPs, calculated according to the DebyeScherrer’s equation, were 19.0 and 16.5 nm, respectively.

Fig 2. XRD patterns of a) CuFe2O4, and b) Fe3O4 NPs

The TEM images of CuFe2O4 and Fe3O4 NPs prepared at 260 °C are shown in Fig.3 (a-b). As can be seen, the obtained particles in both samples are quite monodisperse with spherical shape. The corresponding particle size distribution of each sample is shown in Fig.3 (c-d). The average particle size of CuFe2O4 and Fe3O4 NPs were about 19.9, 18.5 nm, respectively. The particle size obtained by TEM analysis is in good in agreement with the crystallite size estimated by the XRD analysis, indicating the high monodispersity of the prepared samples. The effect of the particle size

on the blood circulation time was investigated by several researchers [27, 28]. It has been reported that the optimal size of nanoparticles for long circulation time in the body is in the range of 10–100 nm. Hence, the both prepared products in this study have potential to be used as a nano-dimensional heater for magnetic hyperthermia applications. 8

Fig 3. TEM images and corresponding particle size distribution of a,c) CuFe2O4 NPs, and b,d) Fe3O4 NPs

The morphology of CuFe2O4 and Fe3O4 NPs along with their elemental mapping analysis was also investigated by SEM analysis and the results are shown in Fig. 4. Almost spherical shaped particles in the nanoscale regime can be observed for both samples. The average particle size for both samples was found in the range of 15-30 nm, which is in good in agreement with the particle size estimated by TEM analysis. Also, the elemental mapping analysis showed good homogenous distribution for all elements in both samples, suggesting the uniformity of products. Moreover, the elemental analysis indicated that the presence of Fe, Cu and O elements in CuFe2O4 sample in the desired ratio. In addition, the presence of C element in both samples

9

could be related to the presence of carbon in the triethylene glycol molecules attached to the surface of nanoparticles.

Fig. 4. SEM images of a) CuFe2O4 NPs and b) Fe3O4 NPs, and elemental mapping analysis of c) CuFe2O4 NPs and d) Fe3O4 NPs

Two strong metal–oxygen bands in the range of 400-1000 cm-1 can be clearly observed in the FT-IR patterns of all ferrite compounds. The first band, usually appeared in the range of 380–450 cm−1, is related to stretching vibrations of metal cations located at octahedral sites, whereas the

10

second one, normally appeared in the range of 550–600 cm−1, is assigned to stretching vibrations of the metal at the tetrahedral sites [29]. The FTIR patterns of the CuFe2O4 and Fe3O4 NPs are displayed in Fig. 5. For CuFe2O4 NPs, the position of the octahedral (Cu-O) and tetrahedral (FeO) stretching vibration peaks was occurred at 436 and 576 cm-1, respectively. It was reported that for the copper ferrite nanoparticles prepared by the sol–gel method, the bonds stretching of Cu– O and Fe–O occur at 422 and 586 cm-1,respectively [30]. The FT-IR spectrum of Fe3O4 NPs also showed two distinct absorption bands, confirming the formation of spinel structure, that are related to the stretching vibrations of Fe-O at the octahedral (445 cm-1) and tetrahedral sites (580 cm-1). The absorption bands occurred in both spectra at 2866 cm-1, 1613cm-1, 1413cm-1 and 1067 cm-1 are assigned to the C-H stretching, C-H bending, C-H bending and C=O stretching vibrations which proves the attachment of TREG on the surface of nanoparticles. Moreover, the broad band around 3400 cm-1 was assigned to the O–H stretching vibrations of the water molecules.

Fig 5. FTIR spectra of a) CuFe2O4 NPs, and b) Fe3O4 NPs

Magnetization curves obtained by VSM analysis for CuFe2O4 and Fe3O4 NPs are shown in Fig. 6, indicating both samples are in the vicinity of transition point from superparamagnetic to single11

domain ferromagnetic state with a minor hysteresis loop area. The magnetic parameters (saturation

magnetization (Ms), coercivity (Hc), and remanence (Mr)) for both samples are presented in Table 1. The saturation magnetization values of CuFe2O4 and Fe3O4 NPs were 53.1 and 58.8 emu/g, respectively. Both values are comparable with those reported in the literature for CuFe2O4 and Fe3O4 NPs [31, 32]. It should be noted that the saturation magnetization of the prepared Fe3O4 is significantly smaller than the bulk magnetization of Fe3O4 (92 emu/g [33]). This behavior can be related to the effect of spin disorder which forms a magnetic dead layer on the surface of nanoparticles and/or maghemite phase conversion [34]. Fig.6b shows the magnified hysteresis loop for both samples. As can be seen, the magnetization of CuFe2O4 NPs in the magnetic field range lower than the safe applied magnetic field used in the magnetic hyperthermia therapy is higher than the magnetization of Fe3O4 NPs. On the other word, in the CuFe2O4 NPs, the approach to saturation is faster, being the magnetization curve slightly more rectangular compared to the Fe3O4 NPs. This could be due to the replacement of Fe ions by soft Cu ions in the octahedral sites of CuFe2O4 NPs which could lead to the decrease in the magnetic anisotropy energy of this sample. In order to confirm this, we have roughly estimated the effective anisotropy for both samples using the law of approach to saturation [35]: 0 = 0 1 − 3⁄

"

(4)

Where Ms is the saturation magnetization and b is correlated with the effect of the magnetocrystalline anisotropy. In the case of uniaxial magnetic crystals, by knowing the fitting

parameter b, the effective anisotropy constant can be estimated using the following equation [35]: 4 55 = 67 0 15 3⁄4

⁄"

(5)

The calculated anisotropy values for CuFe2O4 and Fe3O4 NPs were 6.25×105 and 1.02×106 erg/cm3, respectively. The values of Keff obtained for both samples are in a good agreement with those reported in the literature for these nanoparticles with the same compound [24, 36, 37]. As can be observed the anisotropy energy of CuFe2O4 NPs is lower than Fe3O4 NPs, so it could be

12

expected that by applying a low magnetic field to both samples (less than 300 Oe), CuFe2O4 NPs could produce more heat due to the lower anisotropy energy and higher magnetization.

Table 1. Magnetic parameters of the prepared samples sample

Ms (emu/g)

Mr (emu/g)

Hc(Oe)

Fe3O4

58.8

0.6

7.5

CuFe2O4

53.1

0.5

4.0

Fig. 6. a) Magnetization curves of CuFe2O4 and Fe3O4 NPs, b) magnified hysteresis loop for both samples

The heat generation capability of the prepared nanoparticles was investigated under different AC magnetic fields. In this study, safe magnetic fields with strengths of H=13, 16 and 19 kA/m at a fixed frequency (f=120 kHz), which are permissible for magnetic hyperthermia therapy, were used (H×f values for all magnetic fields were less than 5×109A/m.s) [16, 29]. After applying the magnetic field, the temperature increase of the magnetic fluid containing CuFe2O4 or Fe3O4 NPs (15 mg/mL) as a function of time was recorded and the results are shown in Fig. 7 (a and b). As can be observed, by increasing the field amplitude, the higher temperature level was attained by both samples. In general, three mechanisms are responsible for heat generation by magnetic 13

nanoparticles under a high frequency magnetic field, including: (1) Hysteresis loss, (2) Brownian relaxation, and (3) Neel relaxation [38]. The hysteresis loss which is attributed to shifting domain walls by exposing to an alternating magnetic field occurs in the ferromagnetic nanoparticles and can be measured by integrating the hysteresis loop area for a given material. Also, the relaxation of the magnetic moment in a single-domain nanoparticle may occur either by Néel or Brownian relaxation mode or combination of them, which are the dominant mechanisms for heat production by superparamagnetic nanoparticles [38]. It is important to note that the combination of the all above mentioned mechanisms is more favorable for heat generation. However, as described by Carrey et al., the

heat generation mechanism in the magnetic nanoparticles,

whether they are in the ferromagnetic regime or superparamagnetic regime, is “hysteresis losses” which directly related to the area of their hysteresis loops in an alternating magnetic field [39]. The SAR value calculated according to the equation 1 for each experiment is shown in Fig. 7c and the results are presented in Table 2. As can be seen, the SAR value of CuFe2O4 nanoparticles improves from 24.8 to 44.9 W/g by increasing the magnetic field from 13 to 19 kA/m which is larger than the values reported for the CuFe2O4 NPs prepared by other methods [40]. The high monodispersity with narrow size distribution as well as high magnetic saturation of the prepared sample could be responsible for obtained results. The degradative influence of polydispersity on the heating rate of magnetic nanoparticles has been shown by Rosensweig [41]. Moreover, the SAR values for CuFe2O4 nanoparticles are about two-fold larger than Fe3O4 NPs in all applied magnetic fields. As shown in Fig. 6, CuFe2O4 NPs have a higher magnetization in the low magnetic fields compared to the Fe3O4 NPs. On the other hand, the anisotropy energy of the CuFe2O4 NPs was lower than Fe3O4 NPs. It has been found that, when the applied magnetic field during the hyperthermia experiments is not high enough to overcome the magnetic anisotropy energy barrier, the particles with lower magnetic anisotropy energy would give the better heating efficiency [34, 42-44]. Therefore, the higher heating efficacy of the CuFe2O4 NPs obtained in our study can be attributed to their higher magnetization (in low magnetic fields) and lower anisotropy compared to Fe3O4 NPs. The SAR value of magnetic NPs improves with frequency (f) and strength of the applied magnetic field (H) [45]. As can be observed in Table 2, the SAR value reported for some magnetic nanoparticles is much higher than the maximum SAR obtained in our study. In some cases, this can be explained by the higher applied field amplitude and frequency in comparison to our 14

study. In order to better compare the heating efficiency of the CuFe2O4 and Fe3O4 NPs with other

magnetic nanoparticles, the ILP values (normalized SAR) of the prepared samples were calculated according to the equation (2) and the results are presented in Table 2. Different types of magnetic nanoparticles have shown highly variable ILP values, ranging from 0.15 to about 4.36 nHm2kg-1. The obtained ILP values of the CuFe2O4 NPs under different magnetic field intensities were in the range of 1.04 to 1.23 nHm2 kg−1.The reported ILP values for the commercial Fe3O4 (Feridex and Combidex) ferro-nanofluids which have the FDA approval for biomedical applications is 0.15 nHm2kg−1 [46]. Our ILP values for CuFe2O4 NPs are about 10 times higher than that of commercial one which indicates the potential application of the prepared samples for magnetic hyperthermia therapy.

15

Fig. 7. Temperature vs. time curves for a) CuFe2O4 NPs, and b) Fe3O4 NPs, c) the SAR values of the prepared samples at three different amplitudes

16

Table 2. Comparison between the obtained SAR and ILP values for different magnetic nanoparticles reported in the literature

MNPs

Synthesis method

Frequency (kHz)

Magnetic field (kA/m)

H×f (GA/m s)

SAR (W/g)

ILP (:;<= /?@

Ref.

CuFe2O4

Solvothermal

120

19

1.56

44.9

1.04

Present study

CuFe2O4

Solvothermal

120

16

1.92

38.0

1.23

Present study

CuFe2O4

Solvothermal

120

13

2.28

24.8

1.22

Present study

Fe3O4

Solvothermal

120

19

2.28

18.5

0.43

Present study

Fe3O4

Coprecipitation

522

15.39

8

46.1

0.37

[47]

CoFe2O4

Thermal decomposition

370

20

7.4

25

0.16

[48]

CuFe2O4

Conventional combustion

331

13.5

4

14.63

0.24

[40]

CuFe2O4

Microwave combustion

331

13.5

4

6.48

0.1

[40]

37.3

18.7

2280

3.28

[49]

CoFe2O4@MnFe2O4

Coprecipitation

500

MnFe2O4@CoFe2O4

Wet chemistry

500

37.3

18.7

3034

4.36

[49]

La0.73Sr0.27MnO3

Citrate gel

100

10

1.0

28.8

2.88

[50]

Mn0.5Zn0.5Fe2O4

Hydrothermal

178

6.35

1.1

28.38

3.95

[51]

Zn0.5Ca0.5Fe2O4

Sol-gel

354

10.2

3.6

14.8

0.4

[52]

17

4. Conclusions

Monodisperse CuFe2O4 and Fe3O4 nanoparticles with spherical shape have been successfully synthesized via a solvothermal method. The average particle size of the CuFe2O4 and Fe3O4 nanoparticles was found to be 19.9 and 18.5 nm, respectively. Magnetic measurements showed that both samples are in the vicinity of transition point from superparamagnetic to single-domain ferromagnetic state. The magnetization of CuFe2O4 NPs in the magnetic field range lower than

the safe alternating magnetic field used in the magnetic hyperthermia therapy was higher than the magnetization of Fe3O4 NPs. On the other hand, CuFe2O4 NPs showed a lower anisotropy energy compared to Fe3O4 NPs. The hyperthermia analysis revealed that the maximum SAR value obtained for CuFe2O4 and Fe3O4 NPs in the magnetic field of 19 kAm-1 and 120 kHz are 44.9 and 18.5 Wg-1, respectively, which can be considered suitable for magnetic hyperthermia therapy. The higher SAR value observed for CuFe2O4 NPs might be attributed to the tuning and better matching of their anisotropy energy with frequency and magnetic field intensity used in magnetic hyperthermia experiments. Finally, we found that the ILP value of the CuFe2O4 NPs is about ten times higher than conventional iron oxide nanoparticles.

Acknowledgements

This work was supported by the deputy of research and technology of Arak University.

5. Declarations of interest

None.

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6. References

1. 2. 3. 4. 5.

6. 7. 8. 9.

10.

11.

12.

13. 14. 15. 16. 17.

Cavaliere, R., et al., Selective heat sensitivity of cancer cells. Biochemical and clinical studies. Cancer, 1967. 20(9): p. 1351-1381. Levine, E.M. and E.B. Robbins, Differential temperature sensitivity of normal and cancer cells in culture. Journal of cellular physiology, 1970. 76(3): p. 373-379. Gilchrist, R., et al., Selective inductive heating of lymph nodes. Annals of surgery, 1957. 146(4): p. 596. Giustini, A.J., et al., Magnetic nanoparticle hyperthermia in cancer treatment. Nano Life, 2010. 1(01n02): p. 17-32. Shaterabadi, Z., G. Nabiyouni, and M. Soleymani, Optimal size for heating efficiency of superparamagnetic dextran-coated magnetite nanoparticles for application in magnetic fluid hyperthermia. Physica C: Superconductivity and its Applications, 2018. 549: p. 84-87. Bakoglidis, K., et al., Size-dependent mechanisms in AC magnetic hyperthermia response of ironoxide nanoparticles. IEEE Transactions on Magnetics, 2012. 48(4): p. 1320-1323. Nemati, Z., et al., Enhanced magnetic hyperthermia in iron oxide nano-octopods: size and anisotropy effects. The Journal of Physical Chemistry C, 2016. 120(15): p. 8370-8379. He, S., et al., Maximizing specific loss power for magnetic hyperthermia by hard–soft mixed ferrites. Small, 2018. 14(29): p. 1800135. Khandhar, A.P., R.M. Ferguson, and K.M. Krishnan, Monodispersed magnetite nanoparticles optimized for magnetic fluid hyperthermia: Implications in biological systems. Journal of applied physics, 2011. 109(7): p. 07B310. Shaterabadi, Z., G. Nabiyouni, and M. Soleymani, High impact of in situ dextran coating on biocompatibility, stability and magnetic properties of iron oxide nanoparticles. Materials Science and Engineering: C, 2017. 75: p. 947-956. Behdadfar, B., et al., Synthesis of aqueous ferrofluids of ZnxFe3− xO4 nanopar.cles by citric acid assisted hydrothermal-reduction route for magnetic hyperthermia applications. Journal of Magnetism and Magnetic Materials, 2012. 324(14): p. 2211-2217. Deepak, F.L., et al., A systematic study of the structural and magnetic properties of Mn-, Co-, and Ni-doped colloidal magnetite nanoparticles. The Journal of Physical Chemistry C, 2015. 119(21): p. 11947-11957. Hergt, R., et al., Magnetic particle hyperthermia: nanoparticle magnetism and materials development for cancer therapy. Journal of Physics: Condensed Matter, 2006. 18(38): p. S2919. Martinez-Boubeta, C., et al., Learning from nature to improve the heat generation of iron-oxide nanoparticles for magnetic hyperthermia applications. Scientific reports, 2013. 3: p. 1652. Atkinson, W.J., I.A. Brezovich, and D.P. Chakraborty, Usable frequencies in hyperthermia with thermal seeds. IEEE Transactions on Biomedical Engineering, 1984(1): p. 70-75. Hergt, R., et al., Physical limits of hyperthermia using magnetite fine particles. IEEE Transactions on magnetics, 1998. 34(5): p. 3745-3754. Maier-Hauff, K., et al., Intracranial thermotherapy using magnetic nanoparticles combined with external beam radiotherapy: results of a feasibility study on patients with glioblastoma multiforme. Journal of neuro-oncology, 2007. 81(1): p. 53-60.

19

18.

19.

20. 21.

22. 23.

24. 25.

26.

27. 28. 29. 30.

31. 32.

33. 34. 35. 36. 37.

Maier-Hauff, K., et al., Efficacy and safety of intratumoral thermotherapy using magnetic ironoxide nanoparticles combined with external beam radiotherapy on patients with recurrent glioblastoma multiforme. Journal of neuro-oncology, 2011. 103(2): p. 317-324. Soleymani, M., M. Edrissi, and A.M. Alizadeh, Tailoring La 1− x Sr x MnO 3 (0.25≤ x≤ 0.35) nanoparticles for self-regulating magnetic hyperthermia therapy: an in vivo study. Journal of Materials Chemistry B, 2017. 5(24): p. 4705-4712. Kayani, Z.N., et al., Synthesis of iron oxide nanoparticles by sol–gel technique and their characterization. IEEE Transactions on Magnetics, 2014. 50(8): p. 1-4. Asgari, M., et al., A robust method for fabrication of monodisperse magnetic mesoporous silica nanoparticles with core-shell structure as anticancer drug carriers. Journal of Molecular Liquids, 2019. 292: p. 111367. Cai, W. and J. Wan, Facile synthesis of superparamagnetic magnetite nanoparticles in liquid polyols. Journal of colloid and interface science, 2007. 305(2): p. 366-370. Hachani, R., et al., Polyol synthesis, functionalisation, and biocompatibility studies of superparamagnetic iron oxide nanoparticles as potential MRI contrast agents. Nanoscale, 2016. 8(6): p. 3278-3287. Nemati, Z., et al., Superparamagnetic iron oxide nanodiscs for hyperthermia therapy: Does size matter? Journal of Alloys and Compounds, 2017. 714: p. 709-714. Shaterabadi, Z., G. Nabiyouni, and M. Soleymani, Physics responsible for heating efficiency and self-controlled temperature rise of magnetic nanoparticles in magnetic hyperthermia therapy. Progress in biophysics and molecular biology, 2018. 133: p. 9-19. Ai, L. and J. Jiang, Influence of annealing temperature on the formation, microstructure and magnetic properties of spinel nanocrystalline cobalt ferrites. Current Applied Physics, 2010. 10(1): p. 284-288. Tabata, Y. and Y. Ikada, Phagocytosis of polymer microspheres by macrophages, in New polymer materials. 1990, Springer. p. 107-141. Choi, H.S., et al., Renal clearance of quantum dots. Nature biotechnology, 2007. 25(10): p. 1165. Altincekic, T., et al., Synthesis and characterization of CuFe2O4 nanorods synthesized by polyol route. Journal of Alloys and Compounds, 2010. 493(1-2): p. 493-498. Zakiyah, L.B., et al., Up-scalable synthesis of size-controlled copper ferrite nanocrystals by thermal treatment method. Materials Science in Semiconductor Processing, 2015. 40: p. 564569. Phuruangrat, A., et al., Synthesis of cubic CuFe2O4 nanoparticles by microwave-hydrothermal method and their magnetic properties. Materials Letters, 2016. 167: p. 65-68. Faheem, M., et al., Synthesis of Cu 2 O–CuFe 2 O 4 microparticles from Fenton sludge and its application in the Fenton process: the key role of Cu 2 O in the catalytic degradation of phenol. RSC advances, 2018. 8(11): p. 5740-5748. Gangopadhyay, S., et al., Magnetic properties of ultrafine iron particles. Physical Review B, 1992. 45(17): p. 9778. Jalili, H., et al., The effect of magneto-crystalline anisotropy on the properties of hard and soft magnetic ferrite nanoparticles. Beilstein journal of nanotechnology, 2019. 10(1): p. 1348-1359. Brown Jr, W.F., Theory of the approach to magnetic saturation. Physical Review, 1940. 58(8): p. 736. Pajić, D., et al., Superparamagnetic relaxation in CuxFe3− xO4 (x= 0.5 and x= 1) nanoparticles. Journal of magnetism and magnetic materials, 2004. 281(2-3): p. 353-363. Sarkar, D. and M. Mandal, Static and dynamic magnetic characterization of DNA-templated chain-like magnetite nanoparticles. The Journal of Physical Chemistry C, 2012. 116(5): p. 32273234. 20

38. 39.

40.

41. 42.

43.

44. 45.

46.

47.

48.

49. 50.

51. 52.

Apostolov, A., I. Apostolova, and J. Wesselinowa, Specific absorption rate in Zn-doted ferrites for self-controlled magnetic hyperthermia. The European Physical Journal B, 2019. 92(3): p. 58. Carrey, J., B. Mehdaoui, and M. Respaud, Simple models for dynamic hysteresis loop calculations of magnetic single-domain nanoparticles: Application to magnetic hyperthermia optimization. Journal of Applied Physics, 2011. 109(8): p. 083921. Kombaiah, K., et al., Conventional and microwave combustion synthesis of optomagnetic CuFe2O4 nanoparticles for hyperthermia studies. Journal of Physics and Chemistry of Solids, 2018. 115: p. 162-171. Rosensweig, R.E., Heating magnetic fluid with alternating magnetic field. Journal of magnetism and magnetic materials, 2002. 252: p. 370-374. Barrera, G., et al., Cation distribution effect on static and dynamic magnetic properties of Co1xZnxFe2O4 ferrite powders. Journal of Magnetism and Magnetic Materials, 2018. 456: p. 372380. Bae, S., et al., AC magnetic-field-induced heating and physical properties of ferrite nanoparticles for a hyperthermia agent in medicine. IEEE Transactions on nanotechnology, 2008. 8(1): p. 8694. Caetano, P., et al., Structure, magnetism and magnetic induction heating of NixCo (1-x) Fe2O4 nanoparticles. Journal of Alloys and Compounds, 2018. 758: p. 247-255. Mohapatra, J., et al., Size-dependent magnetic and inductive heating properties of Fe 3 O 4 nanoparticles: scaling laws across the superparamagnetic size. Physical Chemistry Chemical Physics, 2018. 20(18): p. 12879-12887. Jang, J.t., et al., Giant Magnetic Heat Induction of Magnesium-Doped γ-Fe2O3 Superparamagnetic Nanoparticles for Completely Killing Tumors. Advanced Materials, 2018. 30(6): p. 1704362. Kandasamy, G., et al., Functionalized hydrophilic superparamagnetic iron oxide nanoparticles for magnetic fluid hyperthermia application in liver cancer treatment. ACS omega, 2018. 3(4): p. 3991-4005. Salunkhe, A.B., et al., Water dispersible superparamagnetic Cobalt iron oxide nanoparticles for magnetic fluid hyperthermia. Journal of Magnetism and Magnetic Materials, 2016. 419: p. 533542. Lee, J.-H., et al., Exchange-coupled magnetic nanoparticles for efficient heat induction. Nature nanotechnology, 2011. 6(7): p. 418. Soleymani, M., M. Edrissi, and A.M. Alizadeh, Thermosensitive polymer-coated La 0.73 Sr 0.27 MnO 3 nanoparticles: potential applications in cancer hyperthermia therapy and magnetically activated drug delivery systems. Polymer Journal, 2015. 47(12): p. 797. Phong, P., et al., Mn0. 5Zn0. 5Fe2O4 nanoparticles with high intrinsic loss power for hyperthermia therapy. Journal of Magnetism and Magnetic Materials, 2017. 433: p. 76-83. Jasso-Terán, R.A., et al., Synthesis, characterization and hemolysis studies of Zn (1− x) CaxFe2O4 ferrites synthesized by sol-gel for hyperthermia treatment applications. Journal of Magnetism and Magnetic Materials, 2017. 427: p. 241-244.

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Highlights • • •

Monodispersed CuFe2O4 and Fe3O4 nanoparticles were obtained via solvothermal method. Induction heating studies under safe alternating magnetic fields revealed high SAR value for CuFe2O4 nanoparticles. The intrinsic loss power (ILP) of CuFe2O4 nanoparticles was about 1.23 nHm2 kg−1 which is appropriate for hyperthermia therapy