Greener synthesis of magnetite nanoparticles using green tea extract

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Greener synthesis of magnetite nanoparticles using green tea extract and their magnetic properties To cite this article: V C Karade et al 2017 Mater. Res. Express 4 096102

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Mater. Res. Express 4 (2017) 096102

https://doi.org/10.1088/2053-1591/aa892f

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25 July 2017

Greener synthesis of magnetite nanoparticles using green tea extract and their magnetic properties

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21 August 2017 ACCEP TED FOR PUBLICATION

30 August 2017 PUBLISHED

12 September 2017

V C Karade1, P P Waifalkar2, T D Dongle1, Subasa C Sahoo3, P Kollu4,5, P S Patil1,2 and P B Patil6 1

3 4 5

School of Nanoscience and Technology, Shivaji University, Kolhapur 416004, India Department of Physics, Shivaji University, Kolhapur 416004, India Department of Physics, Central University of Kerala, Kasaragod 671314, India CASEST, School of Physics, University of Hyderabad, Gachibowli, Hyderabad 500046, India Thin Film Magnetism group, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge CB3 0HE, United Kingdom 6 Department of Physics, The New College, Kolhapur 416012, India 2

E-mail: [email protected] Keywords: green synthesis, green tea, Fe3O4, magnetic nanoparticles, solvothermal

Abstract The facile green synthesis method has been employed for the synthesis of biocompatible Fe3O4 magnetic nanoparticles (MNPs) using green tea extract. The effective reduction of ferric ions (Fe3+) were done using an aqueous green tea extract where it acts as reducing as well as capping agent. The effect of iron precursor to green tea extract ratio and reaction temperature was studied. The MNPs were characterized by x-ray diffraction, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, dynamic light scattering and vibrating sample magnetometer. It was observed that the reaction temperature strongly affects the magnetic and structural properties of MNPs. The magnetic measurements study showed that Fe3O4 MNPs are superparamagnetic at 300 K, while at 60 K have ferromagnetic as well as superparamagnetic contributions.

1. Introduction The magnetic nanoparticles (MNPs) have numerous applications in the field of biomedical sciences such as targeted drug delivery [1], cell tracking [2], magnetic resonance imaging (MRI) [3], magnetic fluid hyperthermia [4] and so on. The Fe3O4 MNPs offer high saturation magnetization, which makes easy magnetic separation of Fe3O4 MNPs under external magnetic field [5]. There are several reports on the synthesis MNPs where different reducing agents such as hydrazine [6], dimethyl formamide (DMF) [7], sodium borohydride (NaBH4) [8], carbon monoxide (CO) [9] etc were used. These reducing agents are highly reactive chemicals have adverse effects on the environment and hinder the biocompatiblity of MNPs, which leads to limited biomedical applications of chemically reduced MNPs. In order to use MNPs in bio-medical applications, they should be strictly biocompatible. Therefore, the novel and environmentally friendly biogenic reduction/greener synthesis methods are highly soughted. Biogenic reduction methods which includes use of bacteria, fungi, algae and higher plants extracts for reduction can be one of the best options for synthesizing the metal and metal oxide nanoparticles (NPs). Such greener methods are environment-friendly, cost-effective, provide good yield, and have decent reproducibility [10]. The availability of biogenic reductive materials in nature makes them a promising candidate for the synthesis of NPs. Such greenly synthesized biocompatible MNPs are particularly useful for magnetic separation of enzymatic catalysis for reuse [11]. There are several reports on the biogenic synthesis of NPs using bacteria, fungi, algae and higher plants extracts. Different plants extracts have been used to obtain nano zero valent iron (NZVI) (Fe0) and iron oxide NPs [12, 13]. Ahmmad et al have first reported preparation of highly crystallized and mesoporous α-Fe2O3 NPs by a combination of hydrothermal and biosynthesis method [14]. Phumying et al have synthesized Fe3O4 NPs with particle sizes of ~6–30 nm by a hydrothermal method using ferric acetylacetonate and Aloe Vera plant extract solution [15]. The viscosity of the solvent strongly affects the size of the primary nanocrystals, because the increasing viscosities of polyols causes increase in the hydrocarbon chain length [16]. Ethylene glycol (EG) is one of the polyol used © 2017 IOP Publishing Ltd

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in solvothermal process is more viscous than the ethanol and water. Due to high viscosity, EG is expected to slow down the primary nanocrystals formation rate and offer more control over the particle growth in solvothermal synthesis processes. Ahmmad et al and Phumying et al have used water as a solvent and obtained broad particles size distribution. Therefore, the EG can be considered as a better solvent for the preparation of MNPs by solvothermal process. Green tea has been widely used as reducing agent for synthesis of different metal and metal oxide NPs (e.g. Fe, Ag, Au, Fe3O4, etc) [17–20], as the green tea extract contains high polyphenolic compounds. These Polyphenols/Caffeine from the extract forms a complex with metal ions and show both reducing and capping behaviour for NPs [21]. Also, these polyphenolic compounds are biodegradable, nontoxic and water soluble at room temperature, which proves green tea extract as an effective reducing agent compared to other extracts [22]. Makarov et al have prepared iron/iron oxide NPs using different naturally occurring aqueous tea extracts of Hordeum vulgare and Rumex acetosa plants. These extracts contain some organic acids such as oxalic and citric acid which play an important role in stabilization and reduction of iron/iron oxide NPs [23]. Xiao et al prepared hydrophilic Fe3O4 MNPs coated with green tea extracts namely epigallocatechin gallate (EGCG) and epicatechin (EC) and showed green tea catechins as efficient reducing agents. All these reports and many others used water as a solvent to prepare iron and iron oxide NPs which mostly produced nonmagnetic NZVI (Fe0) or iron oxide/ oxyhydroxide NPs with low saturation magnetization value [24]. We have developed a modified green synthesis method to prepare Fe3O4 MNPs using green tea extract as a reducing agent and EG as a solvent. In this study, different preparative parameters of modified green synthesis method are varied to evaluate their effect on magnetic and structural properties of Fe3O4 MNPs.

2.  Materials and methods 2.1. Materials All chemicals were of reagent grade and used as received. Ferric nitrate (Fe(NO3)3·9H2O) and ethylene glycol (CH2(OH)·CH2OH) were purchased from Sd fine-chem India. The standard green tea bags of Tetley were used as received. 2.2.  Preparation of the green tea extract A standard tea bag was immersed in 100 ml double distilled water (DDW) and boiled for half an hour. The tea bag was then removed from the solution and filtered two times with Whatman no-1 filter paper to obtain a clear extract. The green tea extract was then stored at 4 °C for further use. 2.3.  Synthesis of MNPs The synthesis method reported by Xiao et al was modified and employed for the synthesis MNPs [20]. 0.1 M ferric nitrate solution was prepared by dissolving ferric nitrate in EG. The ferric nitrate solution and green tea extract were mixed in 1:2 proportion to obtain a greenish black colored solution which was then stirred it for 30 min. This solution was transferred to Teflon liner, sealed well and kept in the furnace at 180 °C, 200 °C and 220 °C for 2 h. The furnace was cooled to room temperature. To remove the loosely bound organic content over MNPs surface and to neutralize the pH of MNPs, the products were washed several times with ethanol and DDW. Finally, MNPs were dried under vacuum at ambient temperature. 2.4. Characterizations The absorbance was measured using a UV-1800 Shimadzu UV–Visible spectrophotometer. X-ray diffraction (XRD) measurements were done on Bruker AXS D2 phaser diffractometer using Cu-Kα radiation (K  =  1.5406 Å). Fourier transform infrared (FTIR) spectra were recorded at room temperature by ATR method in the range of 560–4000 cm−1 by a Shimadzu FTIR spectrophotometer. Field emission scanning electron microscope (FE-SEM) of Tescan (Mira-3), was employed for particle size investigations. The dynamic light scattering (DLS) and zeta potential measurements were performed at 25 °C using Zetasizer-NanoZs (Malvern Instruments) to obtain Z-Average diameter and surface charge of MNPs. Magnetization measurements were carried out using the vibrating sample magnetometer attached to physical property measurement system (PPMS) of Quantum Design, Inc. Magnetization verses field (MH) loops were measured at 300 K and 60 K in magnetic fields up to 30 kOe. Zero field-cooled (ZFC) and field-cooled (FC) magnetization measurements were performed in the temperature range 50–300 K in an applied magnetic field of 500 Oe.

3.  Results and discussion The amount of green tea extract plays a key role in the development of final structure and size of the NPs [22]. Figure 1(a) shows the UV–Visible absorption spectra for green tea extract, ferric nitrate and mixture of ferric nitrate with extract in 1:6 ratio. The color change from pale yellow to brown was observed after the addition of 2

Mater. Res. Express 4 (2017) 096102

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Figure 1.  (a) Absorption spectra for green tea extract, ferric nitrate and mixture of ferric nitrate with extract in 1:6 (A3) ratio respectively, inset figure. shows a digital photograph of green tea extract, ferric nitrate and sample A3 respectively. (b) Absorption spectra for mixture of ferric nitrate and green tea extract in different ratio, the inset shows a digital photograph mixture of ferric nitrate and green tea extract in different ratio. Table 1.  Addition ratios for preparation of NZVI (Fe0) NPs using Fe(NO3)3 and green tea extract. Sample code

Ratio

Description

A1

1:2

1 ml Fe(NO3)3: 2 ml tea extract

A2

1:4

1 ml Fe(NO3)3: 4 ml tea extract

A3

1:6

1 ml Fe(NO3)3: 6 ml tea extract

A4

1:8

1 ml Fe(NO3)3: 8 ml tea extract

A5

1:10

1 ml Fe(NO3)3: 10 ml tea extract

green tea extract to ferric nitrate solutions in the specified ratio. The green tea extract and ferric nitrate solution have the strong absorption below 500 nm and 600 nm respectively. The mixture obtained after the addition of ferric nitrate and green tea extract solution have slight higher absorption from visible to near infrared region. The formation of Fe3O4 MNPs is possible only when the NZVI (Fe0) NPs nucleates at initial stage. The formation of iron nucleates/NZVI (Fe0) NPs can be confirmed by the appearance of black color of the mixture after the addition of reactants [24, 25]. Hence, to obtain optimum condition for NZVI (Fe0) NPs formation ferric nitrate and green tea extract solutions were added in different ratio (V/V) as listed in table 1. The UV–Visible absorption spectra for mixture of ferric nitrate and green tea extract in different ratio are shown in figure 1(b). With decreasing amount of green tea extract from samples A5 to A1, the intense greenish black color formation was observed. The NZVI (Fe0) NPs, formed at this stage are amorphous and nonmagnetic in nature and do not show any specific absorption peak in absorption spectra [24]. The samples from A5 to A1 shows increasing absorption. For sample A1, the absorption is maximum which indicates the formation of NZVI (Fe0) NPs. The possible mechanism for formation of NZVI (Fe0) NPs has been explained by Wang et al [26]. The polyphenols from tea extract reduces Fe3+ ions from ferric nitrate solutions into Fe2+ ions. These Fe2+ ions are strongly stabilized by polyphenols ligands and form less stable Fe2+-polyphenol complex. But due to autooxidation process these Fe2+ ions get converted to Fe3+-polyphenol complexes. The polyphenols from complex donates 3 electrons to Fe3+ ion and form NZVI (Fe0) NPs. Due to the nonmagnetic nature, NZVI (Fe0) NPs have limited applications. To enhance the magnetic properties of NZVI (Fe0) NPs and to transform them in to Fe3O4 MNPs the thermal treatment has been given. Due to complex chemistry in green synthesis process detailed mechanism for the formation of Fe3O4 MNPs from NZVI (Fe0) NPs have not been established yet. The effect of temperature during synthesis of MNPs were studied by carrying the reactions at 180 °C, 200 °C and 220 °C for 2 h. XRD patterns of Fe3O4 MNPs synthesized at different reaction temperatures are shown in figure 2. The MNPs prepared at 180 °C (G1) have the amorphous nature and does not show any crystalline peak in the pattern which indicates that NZVI (Fe0) NPs have not transformed to iron oxide phase [27]. The solvent EG used for the solvothermal process has boiling point of 200 °C, therefore the 180 °C reaction temperature might be insufficient for reaction to occour [28]. The sample prepared with reaction temperature at 200 °C (G2) reveals the growth of the crystal with pure magnetite phase. All the diffraction peaks in XRD pattern are assigned to the lattice planes (2 2 0), (3 1 1), (5 1 1) and (4 4 0) of magnetite (JCPDS no.-01-088-0315). No other diffraction peaks for phase impurity were observed signifying the successful synthesis of pure magnetite phase. The MNPs 3

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Figure 2.  X-ray diffraction patterns of Fe3O4 MNPs for samples G1, G2 and G3 synthesized with different reaction temperature at 180 °C, 200 °C and 220 °C for 2 h respectively.

Figure 3.  FT-IR spectrums for (a) green tea extract and (b) greenly synthesized Fe3O4 MNPs for sample G2, the inset shows Fe–O bond stretch.

prepared at 220 °C (G3) shows the lower crystallinity as compared to those prepared at 200 °C (G2). The lower crystallinity may occur due to decomposition of the organic matter in green tea extract and EG at higher temper­ ature which inhibits the crystal growth [28]. The crystallite size was calculated by Debye–sheerer formula using most intense peak (3 1 1). The average crystallite size for the samples G2 and G3 was found to be 7 nm and 13 nm respectively. 4

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Figure 4.  FE-SEM micrographs of Fe3O4 MNPs for (a) sample G2 (b) magnified micrograph of sample G2.

Figure 5.  DLS analysis of sample G2 (a) particle size distribution by intensity (b) zeta potential.

Fe3O4 MNPs (G2) and green tea extract was analyzed by FT-IR spectroscopy and results are shown in figure 3. The FT-IR spectra of green extract shown in figure 3(a) exhibits strong peaks around 1640 cm−1 and 3300 cm−1 which corresponds to the alkene (C=C) stretching vibrations and phenolic hydroxyl groups (–OH) respectively, indicating the hydrogen bonding between the tea polyphenols [20, 29]. The figure 3(b) shows FT-IR spectra of greenly reduced MNPs. The occurrence of the Fe–O bond (inset figure 3) around 626 cm−1 confirms the formation of iron oxide in the greenly synthesized MNPs. The similar stretching vibration around 626 cm−1 corresponding to Fe–O bond is observed to Yamura et al and Raid et al [30, 31]. The absorption peak observed 5

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Figure 6.  Shows room temperature (300 K) and low temperature (60 K) M versus H hysteresis loops for sample G1, G2 and G3 in (a), (d) and (g) respectively. Low temperature (60 K) M versus H curve in enlarged scale for sample G1, G2 and G3 in (b), (e) and (h) respectively. ZFC and FC magnetization (H  =  500 Oe) for sample G1, G2 and G3 in (c), (f) and (j) respectively.

Table 2.  Comparative magnetization data for sample G1, G2 and G3.

Particle size (nm)

Saturation magnetization (Ms) (emu g−1)

Coercivity (Hc) (Oe)

Irreversible temperature (Tirr) K

Sample code

Reaction temperature (°C)

G1

180

7

7

0

0

G2

200

7

25

30

0

46

90

G3

220

13

19

26

0

77

70

XRD

300 K

Amorphous

60 K

300 K

60 K

-

around 820 cm−1 and 1315 cm−1 are ascribed to the C−O−C and aromatic C−OH stretching modes respectively [20]. The stretching vibrations at 1640 cm−1 and 3300 cm−1 corresponding to polyphenols were also observed in MNPs. The occurrence of stretching vibrations of polyphenols in MNPs confirms the capping activity of magnetite surface by tea polyphenols. Field emission scanning electron microscope (FE-SEM) studies of greenly synthesized Fe3O4 MNPs were carried out to determine the shape and size of the MNPs. Figure 4(a) shows representative (FE-SEM) for sample G2. It can be seen that the greenly synthesized Fe3O4 MNPs exhibits spherical morphology. However, the agglomerated state of MNPs occur due to the hydroxyl content above the surface of MNPs from extract [32]. The enlarged view for sample G2 in figure 4(b) shows the spherical MNPs have size of ~25 to 30 nm. Figure 5(a) shows DLS analysis of sample G2 and corresponding zeta potential measurement is shown figure 5(b). The DLS measurements for sample G2 was performed in aqueous suspensions displayed polydispersive behavior. An average size of greenly synthesized MNPs has found to be 337 nm. The average size of MNPs obtained by DLS is higher than that observed in FESEM, possibly due to a nonuniform size distribution and/or aggregation of MNPs in solution. The zeta potential for sample G2 is about  −18.5 mV evidences greenly synthesized MNPs exhibits good colloidal stability. 6

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The room temperature (300 K) and low temperature (60 K) magnetization curves of the greenly synthesized MNPs and temperature dependent magnetic behavior by zero field cooling (ZFC) and field cooling (FC) measurements are shown in figure 6. As can be seen from the figures 6(a), (d) and (g), the magnetization curves measured at 300 K for all three samples does not saturates even at 30 kOe. Also, all the samples have zero coercivity at 300 K, indicating the Fe3O4 MNPs are superparamagnetic [15]. Low temperature (60 K) magnetization data also reveals that all the samples does not saturates at 30 kOe. The hysteresis loops measured at 60 K for all the samples are plotted in the enlarged scale and are shown in figures 6(b), (e) and (h). The sample G1 has zero coercivity at 60 K. The sample G2 and G3 exhibits hysteresis which indicates the presence of ferromagnetic particles along with superparamgantic particles. The results obtained for FC and ZFC measurements are shown in figure 6(c), (f) and (i), the solid and open circles are the FC and ZFC data respectively. In the case of sample G1 reversibility is observed in ZFC and FC curves, which indicates the sample has its blocking temperature below the measured range of 50 K. For the sample G2 and G3 the irreversibility temperature (tirr), at which separation of the ZFC and FC curves occurrs, is 91 K and 70 K observed respectively [20]. The sample G2 and G3 also have the blocking temperature below measured range of 50 K. The parameters obtained from the magnetic study for all the samples are tabulated in table 2. Sample G1 has extremely low saturation magnetization as compared to G2 and G3 and zero coercivity at 60 K and 300 K. The sample G2 has better saturation magnetization (Ms) value of about 25 emu g−1 than sample G3 which has Ms of 19 emu g−1 at 300 K. The saturation magnetization for all the samples is less than that of bulk Fe3O4 [33]. The low temperature magnetization measurements for the samples G2 and G3 showed that the Ms values at 60 K are greater than that of measured at 300 K. Also, sample G2 has higher Ms (30 emu g−1) and lower Hc (46 Oe) compared to sample G3 having Ms (26 emu g−1) and Hc (77 Oe) respectively. The similar behavior of increment in the coercivity values with increasing reaction temperature was also observed by Ozel et al [34]. The satur­ation magnetization values obtained by our method are greater than other green synthesis methods reported in literature. Prasad et al have reported the synthesis of iron oxide nanoparticles using watermelon rind extract, they have found the saturation magnetization (Ms) value about 14.2 emu g−1 [35]. Venkateswarlu et al reported Fe3O4 magnetic nanorods using Punica Granatum rind extract having Ms value about 22.7 emu g−1 [36]. Xiao et al have obtained lower Ms value of 16.7 emu g−1, 14.8 emu g−1, and 20.2 emu g−1 for different Fe3O4 MNPs synthesized using green tea extract [20].

4. Conclusions The Fe3O4 MNPs having particle size of ~25–30 nm has been successfully synthesized by a modified greener synthesis method using green tea extract. The sample G2 prepared at 200 °C temperature in solvothermal reaction has a saturation magnetization of 25 emu g−1 at room temperature which is better than many MNPs prepared by green synthesis methods reported in literature. The XRD and FE-SEM results revealed that the synthesized Fe3O4 MNPs have pure magnetite phase and have a spherical morphology. All the samples are not saturating at 30 kOe and 300 K with zero coercivity indicating superparamagnetic nature. At 60 K samples G2 and G3 are not saturating but shows hysteresis behavior. This indicates both the ferromagnetic and superparamagnetic contributions in greenly prepared MNPs. Magnetite MNPs prepared using green tea extract can be useful for many applications, where biocompatibility is of importance.

Acknowledgment PBP acknowledges the funding received from Department of Biotechnology, Government of India, under STAR college scheme.

References [1] McBain S C, Yiu H H P and Dobson J 2008 Magnetic nanoparticles for gene and drug delivery Int. J. Nanomed. 3 169–80 [2] Hachani R, Lowdell M, Birchall M and Thanh N T K 2013 Tracking stem cells in tissue-engineered organs using magnetic nanoparticles Nanoscale 5 11362 [3] Estelrich J, Sinchez-Martin M J and Busquets M A 2015 Nanoparticles in magnetic resonance imaging: from simple to dual contrast agents Int. J. Nanomed. 10 1727–41 [4] Kim D H, Lee S H, Im K H, Kim K N, Kim K M, Shim I B, Lee M H and Lee Y-K 2006 Surface-modified magnetite nanoparticles for hyperthermia: preparation, characterization, and cytotoxicity studies Curr. Appl. Phys. 6 242–6 [5] Mohamed S A, Al-Harbi M H, Almulaiky Y Q, Ibrahim I H and El-Shishtawy R M 2017 Immobilization of horseradish peroxidase on Fe3O4 magnetic nanoparticles Electron. J. Biotechnol. 27 84–90 [6] Hou Y, Kondoh H, Shimojo M, Sako E O, Ozaki N, Kogure T and Ohta T 2005 Inorganic nanocrystal self-assembly via the inclusion interaction of  β-cyclodextrins: toward 3D spherical magnetite J. Phys. Chem. B 109 4845–52

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V C Karade et al

[7] Jian P, Yahui H, Yang W and Linlin L 2006 Preparation of polysulfone-Fe3O4 composite ultrafiltration membrane and its behavior in magnetic field J. Membr. Sci. 284 9–16 [8] Cain J L, Harrison S R, Nikles J A and Nikles D E 1996 Preparation of α-Fe particles by reduction of ferrous ion in lecithin/cyclohexane/ water association colloids J. Magn. Magn. Mater. 155 67–9 [9] Mondal K, Lorethova H, Hippo E, Wiltowski T and Lalvani S B 2004 Reduction of iron oxide in carbon monoxide atmosphere— reaction controlled kinetics Fuel Process. Technol. 86 33–47 [10] Xu J-K, Zhang F-F, Sun J-J, Sheng J, Wang F and Sun M 2014 Bio and nanomaterials based on Fe3O4 Molecules 19 21506–28 [11] Waifalkar P P, Parit S B, Chougale A D, Sahoo S C, Patil P S and Patil P B 2016 Immobilization of invertase on chitosan coated γ-Fe2O3 magnetic nanoparticles to facilitate magnetic separation J. Colloid Interface Sci. 482 159–64 [12] Saif S, Tahir A and Chen Y 2016 Green synthesis of iron nanoparticles and their environmental applications and implications Nanomaterials 6 209 [13] Siddiqi K S, Rahman A, Tajuddin U and Husen A 2016 Biogenic fabrication of iron/iron oxide nanoparticles and their application Nanoscale Res. Lett. 11 498 [14] Ahmmad B, Leonard K, Shariful Islam M, Kurawaki J, Muruganandham M, Ohkubo T and Kuroda Y 2012 Green synthesis of mesoporous hematite (α-Fe2O3) nanoparticles and their photocatalytic activity Adv. Powder Technol. 24 160–7 [15] Phumying S, Labuayai S, Thomas C, Amornkitbamrung V, Swatsitang E and Maensiri S 2013 Aloe vera plant-extracted solution hydrothermal synthesis and magnetic properties of magnetite (Fe3O4) nanoparticles Appl. Phys. A 111 1187–93 [16] Huang Z, Wu K, Yu Q H, Wang Y Y, Xing J and Xia T L 2016 Facile synthesis of size tunable Fe3O4 nanoparticles in bisolvent system Chem. Phys. Lett. 664 219–25 [17] Huang L, Weng X, Chen Z, Megharaj M and Naidu R 2014 Green synthesis of iron nanoparticles by various tea extracts: comparative study of the reactivity Spectrochim. Acta A 130 295–301 [18] Loo Y Y, Chieng B W, Nishibuchi M and Radu S 2012 Synthesis of silver nanoparticles by using tea leaf extract from Camellia Sinensis Int. J. Nanomed. 7 4263–7 [19] Sharma R K, Gulati S and Mehta S 2012 Preparation of gold nanoparticles using tea: a green chemistry experiment J. Chem. Educ. 89 1316–8 [20] Xiao L, Mertens M, Wortmann L, Kremer S, Valldor M, Lammers T, Kiessling F and Mathur S 2015 Enhanced in vitro and in vivo cellular imaging with green tea coated water-soluble iron oxide nanocrystals ACS Appl. Mater. Interfaces 7 6530–40 [21] Nadagouda M N and Varma R S 2008 Green synthesis of silver and palladium nanoparticles at room temperature using coffee and tea extract Green Chem. 10 859 [22] Nadagouda M N, Castle A B, Murdock R C, Hussain S M and Varma R S 2010 In vitro biocompatibility of nanoscale zerovalent iron particles (NZVI) synthesized using tea polyphenols Greem Chem. 12 114–22 [23] Makarov V V, Makarova S S, Love A J, Sinitsyna O V, Dudnik A O, Yaminsky I V, Taliansky M E and Kalinina N O 2014 Biosynthesis of stable iron oxide nanoparticles in aqueous extracts of Hordeum vulgare and Rumex acetosa plants Langmuir 30 5982–8 [24] Huang L, Luo F, Chen Z, Megharaj M and Naidu R 2015 Green synthesized conditions impacting on the reactivity of Fe NPs for the degradation of malachite green Spectrochim. Acta A 137 154–9 [25] Kumar B, Smita K, Cumbal L, Debut A, Galeas S and Guerrero V H 2016 Phytosynthesis and photocatalytic activity of magnetite (Fe3O4) nanoparticles using the Andean blackberry leaf Mater. Chem. Phys. 179 310–5 [26] Wang Z 2013 Iron complex nanoparticles synthesized by eucalyptus leaves ACS Sustain. Chem. Eng. 1 1551–4 [27] Shahwan T, Abu Sirriah S, Nairat M, Boyaci E, Eroĝlu A E, Scott T B and Hallam K R 2011 Green synthesis of iron nanoparticles and their application as a Fenton-like catalyst for the degradation of aqueous cationic and anionic dyes Chem. Eng. J. 172 258–66 [28] Yang X, Jiang W, Liu L, Chen B, Wu S, Sun D and Li F 2012 One-step hydrothermal synthesis of highly water-soluble secondary structural Fe3O4 nanoparticles J. Magn. Magn. Mater. 324 2249–57 [29] Huang L, Weng X, Chen Z, Megharaj M and Naidu R 2014 Synthesis of iron-based nanoparticles using oolong tea extract for the degradation of malachite green Spectrochim. Acta A 117 801–4 [30] Yamaura M, Camilo R L, Sampaio L C, Macêdo M A, Nakamura M and Toma H E 2004 Preparation and characterization of (3-aminopropyl)triethoxysilane-coated magnetite nanoparticles J. Magn. Magn. Mater. 279 210–7 [31] Ismail R A, Sulaiman G M, Abdulrahman S A and Marzoog T R 2015 Antibacterial activity of magnetic iron oxide nanoparticles synthesized by laser ablation in liquid Mater. Sci. Eng. C 53 286–97 [32] Venkateswarlu S, Natesh Kumar B, Prasad C H, Venkateswarlu P and Jyothi N V V 2014 Bio-inspired green synthesis of Fe3O4 spherical magnetic nanoparticles using Syzygium cumini seed extract Physica B 449 61–71 [33] Panda R N, Gajbhiye N S and Balaji G 2001 Magnetic properties of interacting single domain Fe3O4 particles J. Alloys Compd. 326 50–3 [34] Ozel F, Kockar H and Karaagac O 2014 Growth of iron oxide nanoparticles by hydrothermal process: effect of reaction parameters on the nanoparticle size J. Supercond. Novel Magn. 28 823–9 [35] Prasad C, Gangadhara S and Venkateswarlu P 2016 Bio-inspired green synthesis of Fe3O4 magnetic nanoparticles using watermelon rinds and their catalytic activity Appl. Nanosci. 6 797–802 [36] Venkateswarlu S, Kumar B N, Prathima B, SubbaRao Y and Jyothi N V V 2014 A novel green synthesis of Fe3O4 magnetic nanorods using Punica Granatum rind extract and its application for removal of Pb(II) from aqueous environment Arab. J. Chem. 1–9

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