Elsevier

Journal of Molecular Liquids

Volume 274, 15 January 2019, Pages 653-663
Journal of Molecular Liquids

One-step synthesis of hydrophilic functionalized and cytocompatible superparamagnetic iron oxide nanoparticles (SPIONs) based aqueous ferrofluids for biomedical applications

https://doi.org/10.1016/j.molliq.2018.10.161Get rights and content

Highlights

  • Direct synthesis of hydrophilic SPIONs via thermolysis for biomedical applications

  • Amine (-NH2) surface functionalized SPIONs based aqueous ferrofluids are obtained.

  • Improved magnetization & high water dispersibility/solubility are attained.

  • Excellent in vitro cytocompatibility and intracellular uptake are achieved.

Abstract

This work systematically describes one-step synthesis of hydrophilic functionalized superparamagnetic iron oxide nanoparticles (SPIONs) via thermolysis in presence of polyamines such as diethylene triamine (DETA), triethylene tetraamine (TETA), tetraethylene pentamine (TTEPA), or pentaethylene hexamine (PEHA) or mixture of a polyamine (TETA) and polyols such as diethylene glycol (DEG), triethylene glycol (TEG) or tetraethylene glycol (TTEG) while varying the polyamine: polyol (v/v) ratio, reaction temperature and reaction time. The saturation magnetization (Ms) values of the as-prepared polyamine (DETA/TETA/TTEPA/PEHA) coated SPIONs are determined in the range of 31.8–48.5 emu/g, which is altered in the range of 40.2–57.8 emu/g by the addition of a polyol (DEG/TEG/TTEG) to the polyamine (TETA) at different ratios. Moreover, the Ms. values are further improved to 64.6 and 66.8 emu/g at the optimized TETA:TEG (1:1) ratio by prolonging the reaction time up-to 2 h and the reaction temperature to 270 °C, respectively. In addition, the TETA-TEG coated SPIONs have displayed their average particle sizes, hydrodynamic sizes, and zeta potential (ζ) values in the range of 7–11 nm, 99–120 nm and +45 to +57 mV, respectively (indicating high water solubility). Finally, the TETA-TEG coated SPIONs with the highest Ms. and ζ values (i.e. 66.8 emu/g and +57 mV) are selected for the biological studies, where they have revealed excellent (i) cytocompatibility, and (ii) intracellular uptake in the cancer (HepG2 liver & MCF-7 breast) cells for the incubation periods of 24/48 h. Thus, the TETA-TEG coated SPIONs based aqueous ferrofluids have a great potential to be used in biomedical applications.

Introduction

Nowadays, several magnetic nanostructured materials are constantly being developed/modified for the biomedical applications [[1], [2], [3], [4], [5]]. Recently, superparamagnetic iron oxide nanoparticles (SPIONs – particularly magnetite (Fe3O4)/maghemite (Fe2O3)) have been enormously attracted in different applications such as magnetic targeting [[6], [7], [8]], magnetofection [[9], [10], [11], [12]], magnetic fluid hyperthermia (MFH) [[13], [14], [15], [16], [17]] and magnetic resonance imaging (MRI) [[18], [19], [20], [21], [22]] due to their unique magnetic properties, excellent chemical stability and biodegradability [[23], [24], [25]]. However, for effective utilization of the SPIONs in the biomedical fields, they should possess high magnetization, better cytocompatibility and good water dispersibility/solubility (to be used in the form of ferrofluids) which might be altered during their chemical synthesis.

Till date, thermolysis (i.e., thermal decomposition of the iron precursors at elevated temperature) in the presence of high boiling-point non-polar solvents (for e.g., phenyl/benzyl ether), and organic stabilizers/surfactants (for e.g., oleic acid/oleylamine) is one of the very capable methods for synthesizing high quality SPIONs with enhanced crystallinity/saturation magnetization (Ms) and uniform particle size distribution [26,27]. But, these as-synthesized hydrophobic SPIONs can only be dispersed in the organic solvents (e.g., hexane) to form non-aqueous ferrofluids, which are not straightway useful for their biomedical applications. Therefore, surface of these hydrophobic SPIONs should be modified further to convert them into hydrophilic – either via ligand exchange/bilayer stabilization processes [[28], [29], [30], [31]], or polymeric encapsulation methods [[32], [33], [34], [35], [36]] – to form aqueous ferrofluids (AFFs) for instant utilization. Nevertheless, these surface modification procedures (i) are very complicated/time-consuming, and (ii) might significantly affect the magnetization and/or biocompatibility of the SPIONs. Furthermore, there is also a risk of dissociation of the modified hydrophilic surface coatings/layers which might eventually lead to the aggregation of the SPIONs in the aqueous ferrofluid suspensions (AFFs). Recently, polyols (for e.g., diethylene glycol (DEG), triethylene glycol (TEG), tetraethylene glycol (TTEG)) have been extensively used as the high boiling-point polar solvents/stabilizing agents to directly synthesize the hydrophilic SPIONs based AFFs via thermolysis [37,38]. However, these hydrophilic SPIONs are incapable for further bio-conjugations due to lack of their effective surface functional groups.

To overcome this issue, Qu et al. have lately demonstrated the use of polyamines (for e.g., triethylene tetraamine (TETA)) in thermolysis to directly synthesize hydrophilic amine (-NH2) functionalized SPIONs which could be effortlessly bio-conjugated with the biomolecules such as biotin and streptavidin [39,40]. However, the synthesis of hydrophilic SPIONs using other polyamines (apart from TETA) has not been explored. Moreover, there is need for systematic investigations of the physicochemical/magnetic properties, water solubility/dispersibility and cytocompatibility of these amine functionalized SPIONs for their effective utilizations for the biomedical applications.

Therefore, in this work, we have prepared hydrophilic functionalized SPIONs via one-step thermolysis by using the polyamines such as diethylene triamine (DETA), TETA, tetraethylene pentamine (TTEPA) and pentaethylene hexamine (PEHA) or the mixture of a polyamine (TETA) and polyols (DEG/TEG/TTEG) while varying their ratio, reaction temperature and reaction time. Subsequently, their physicochemical/magnetic properties such as size/morphology, crystalline/surface structure, magnetization and water dispersibility/solubility are systematically investigated. Finally, the cytocompatibility and intracellular uptake of the as-prepared amine-functionalized SPIONs are inspected using the cancer cell lines (MCF-7 and HepG2) to evaluate their potentiality for biomedical applications.

Section snippets

Materials

Iron (III) acetylacetonate (Fe(acac)3), potassium hexacyanoferrate (C6N6FeK3), and potassium thiocyanate (KSCN) are purchased from Sigma-Aldrich. Diethylene glycol (DEG), diethylene triamine (DETA), triethylene glycol (TEG), triethylene tetraamine (TETA), tetraethylene glycol (TTEG), tetraethylene pentamine (TEPA), pentaethylene hexamine (PEHA), ethanol and ethyl acetate are obtained from Fisher Scientific. Fetal bovine serum (FBS), phosphate buffer saline (PBS) and Dulbecco's modified eagle

Effects of polyamines

Initially, the SPIONs are synthesized via thermolysis in the presence of different polyamines such as DETA, TETA, TTEPA, and PEHA at their corresponding refluxing/reaction temperature for 1 h to obtain the samples - S1, S2, S3 and S4, respectively (refer Table 1).

Fig. 1(i–iv) show the respective TEM images of S1–S4 samples and the average particle sizes of these samples are determined (using Image J software) as 6.1 ± 0.9, 7.0 ± 1.4, 7.2 ± 2.5, and 9.7 ± 3.2 nm, respectively. It can be seen

Conclusions

In summary, we report the synthesis of hydrophilic functionalized SPIONs via one-step thermolysis of iron (III) acetylacetonate by using the polyamines or mixture of polyamines and polyols. However, the as-prepared polyamines (DETA/TETA/TTEPA/PEHA) coated SPIONs (i.e. S1–S4) demonstrated lower Ms. values ranging from 31.8–48.5 emu/g. The magnetization values of the SPIONs are gradually improved from 51.9 to 57.8 emu/g by the addition of increased amount of TEG to TETA from 4:1 to 1:1 v/v ratio

Acknowledgments

The financial supports obtained from the following funding agencies are highly acknowledged: (i) Nanomission (Grant No. SR/NM/NS-1141/2015 (G)), Department of Science and Technology (DST), New Delhi, India and (ii) Shiv Nadar University, Uttar Pradesh, India.

References (72)

  • N. Ali et al.

    Key synthesis of magnetic Janus nanoparticles using a modified facile method

    Particuology

    (2014)
  • J. Wang et al.

    One-pot synthesis of water-soluble superparamagnetic iron oxide nanoparticles and their MRI contrast effects in the mouse brains

    Mater. Sci. Eng. C

    (2015)
  • M. Aydın et al.

    Synthesis, magnetic and electrical characteristics of poly(2‑thiophen‑3‑yl‑malonic acid)/Fe3O4 nanocomposite

    J. Alloys Compd.

    (2012)
  • D. Maity et al.

    Studies of magnetite nanoparticles synthesized by thermal decomposition of iron (III) acetylacetonate in tri(ethylene glycol)

    J. Magn. Magn. Mater.

    (2009)
  • D. Maity et al.

    Synthesis of iron oxide nanoparticles under oxidizing environment and their stabilization in aqueous and non-aqueous media

    J. Magn. Magn. Mater.

    (2007)
  • S.L. Gawali et al.

    Effect of sugar alcohol on colloidal stabilization of magnetic nanoparticles for hyperthermia and drug delivery applications

    J. Alloys Compd.

    (2017)
  • R.P. Araújo-Neto et al.

    Monodisperse sodium oleate coated magnetite high susceptibility nanoparticles for hyperthermia applications

    J. Magn. Magn. Mater.

    (2014)
  • S.V. Jadhav et al.

    PVA and PEG functionalised LSMO nanoparticles for magnetic fluid hyperthermia application

    Mater. Charact.

    (2015)
  • S. Xie et al.

    Superparamagnetic iron oxide nanoparticles coated with different polymers and their MRI contrast effects in the mouse brains

    Appl. Surf. Sci.

    (2015)
  • N.D. Thorat et al.

    Enhanced colloidal stability of polymer coated La0.7Sr0.3MnO3 nanoparticles in physiological media for hyperthermia application

    Colloids Surf. B: Biointerfaces

    (2013)
  • R.M. Patil et al.

    In vitro hyperthermia with improved colloidal stability and enhanced SAR of magnetic core/shell nanostructures

    Mater. Sci. Eng. C

    (2016)
  • Q.A. Pankhurst et al.

    Applications of magnetic nanoparticles in biomedicine

    J. Phys. D. Appl. Phys.

    (2003)
  • D. Kami et al.

    Application of magnetic nanoparticles to gene delivery

    Int. J. Mol. Sci.

    (2011)
  • A. Ali et al.

    Synthesis, characterization, applications, and challenges of iron oxide nanoparticles

    Nanotechnol. Sci. Appl.

    (2016)
  • H. Chen et al.

    Rethinking cancer nanotheranostics

    Nat. Rev. Mater.

    (2017)
  • L. Prosen et al.

    Magnetofection: a reproducible method for gene delivery to melanoma cells

    Biomed. Res. Int.

    (2013)
  • C.A. Hong et al.

    Functional nanostructures for effective delivery of small interfering RNA therapeutics

    Theranostics

    (2014)
  • S.-J. Huang et al.

    One-pot synthesis of PDMAEMA-bound iron oxide nanoparticles for magnetofection

    J. Mater. Chem. B

    (2013)
  • E.A. Périgo et al.

    Fundamentals and advances in magnetic hyperthermia

    Appl. Phys. Rev.

    (2015)
  • B. Kozissnik et al.

    Magnetic fluid hyperthermia: advances, challenges, and opportunity

    Int. J. Hyperth.

    (2013)
  • V.F. Cardoso et al.

    Advances in magnetic nanoparticles for biomedical applications

    Adv. Healthc. Mater.

    (2018)
  • D. Maity et al.

    Facile synthesis of water-stable magnetite nanoparticles for clinical MRI and magnetic hyperthermia applications

    Nanomedicine

    (2010)
  • F. Hu et al.

    High-performance nanostructured MR contrast probes

    Nanoscale

    (2010)
  • R.R.T. Ragheb et al.

    Induced clustered nanoconfinement of superparamagnetic iron oxide in biodegradable nanoparticles enhances transverse relaxivity for targeted theranostics

    Magn. Reson. Med.

    (2013)
  • H. Bin Na et al.

    Inorganic nanoparticles for MRI contrast agents

    Adv. Mater.

    (2009)
  • J. Mosayebi et al.

    Synthesis, functionalization, and Design of Magnetic Nanoparticles for Theranostic applications

    Adv. Healthc. Mater.

    (2017)
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