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Polyethylene Glycol-Mediated Synthesis of Cubic Iron Oxide Nanoparticles with High Heating Power.

Iacovita C, Stiufiuc R, Radu T, Florea A, Stiufiuc G, Dutu A, Mican S, Tetean R, Lucaciu CM - Nanoscale Res Lett (2015)

Bottom Line: Iron oxide magnetic nanoparticles (IOMNPs) have been successfully synthesized by means of solvothermal reduction method employing polyethylene glycol (PEG200) as a solvent.The specific absorption rate (SAR) values increase with decreasing nanoparticle concentrations for the IOMNPs dispersed in water.By dispersing the IOMNPs in PEG600 (liquid) and PEG1000 (solid), it was found that the SAR values decrease by 50 or 75 %, indicating that the Brownian friction within the solvent was the main contributor to the heating power of IOMNPs.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical Physics-Biophysics, Faculty of Pharmacy, "Iuliu Hatieganu" University of Medicine and Pharmacy, Pasteur 6, 400349, Cluj-Napoca, Romania. cristian.iacovita@umfcluj.ro.

ABSTRACT
Iron oxide magnetic nanoparticles (IOMNPs) have been successfully synthesized by means of solvothermal reduction method employing polyethylene glycol (PEG200) as a solvent. The as-synthesized IOMNPs are poly-dispersed, highly crystalline, and exhibit a cubic shape. The size of IOMNPs is strongly dependent on the reaction time and the ration between the amount of magnetic precursor and PEG200 used in the synthesis method. At low magnetic precursor/PEG200 ratio, the cubic IOMNPs coexist with polyhedral IOMNPs. The structure and morphology of the IOMNPs were thoroughly investigated by using a wide range of techniques: TEM, XRD, XPS, FTIR, and RAMAN. XPS analysis showed that the IOMNPs comprise a crystalline magnetite core bearing on the outer surface functional groups from PEG200 and acetate. The presence of physisorbed PEG200 on the IOMNP surface is faintly detected through FT-IR spectroscopy. The surface of IOMNPs undergoes oxidation into maghemite as proven by RAMAN spectroscopy and the occurrence of satellite peaks in the Fe2p XP spectra. The magnetic studies performed on powder show that the blocking temperature (TB) of IOMNPs is around 300 K displaying a coercive field in between 160 and 170 Oe. Below the TB, the field-cooled (FC) curves turn concave and describe a plateau indicating that strong magnetic dipole-dipole interactions are manifested in between IOMNPs. The specific absorption rate (SAR) values increase with decreasing nanoparticle concentrations for the IOMNPs dispersed in water. The SAR dependence on the applied magnetic field, studied up to magnetic field amplitude of 60 kA/m, presents a sigmoid shape with saturation values up to 1700 W/g. By dispersing the IOMNPs in PEG600 (liquid) and PEG1000 (solid), it was found that the SAR values decrease by 50 or 75 %, indicating that the Brownian friction within the solvent was the main contributor to the heating power of IOMNPs.

No MeSH data available.


Related in: MedlinePlus

TEM images (a, c) of water-soluble cubic and polyhedral IOMNPs obtained in 90 ml of PEG200 for 6- and 12-h reaction time and their corresponding size distribution histograms (b, d) fitted to a log-normal distribution (black line)
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Fig2: TEM images (a, c) of water-soluble cubic and polyhedral IOMNPs obtained in 90 ml of PEG200 for 6- and 12-h reaction time and their corresponding size distribution histograms (b, d) fitted to a log-normal distribution (black line)

Mentions: Furthermore, the PEG200 volume was increased to 90 ml while keeping unchanged the reaction condition. In this case, the TEM images exhibited the coexistence of poly-dispersed cubic and polyhedral IOMNPs (Fig. 2a, c) with lower dimensions. As expected, the size of IOMNPs gradually increased with the reaction time. For instance, for a reaction time of 6 h at 240 °C, the IOMNPs have a mean size of 30 nm, whereas for 12 h, the mean size increases around 48 nm (Fig. 2b, d). No significant changes in the morphology and size were observed when the PEG200 volume was further increased to 120 ml. It is worth noting that we could not increase the reaction temperatures above 240 °C as PEG200 starts to boil. Also, below 240 °C, the nanoparticle synthesis cannot be performed. At the same time, for a reaction temperature of 240 °C, the synthesis can be completed only for reaction times longer than 6 h. Consequently, the formation of IOMNPs in the proposed solvothermal system, employing PEG200 as reducing agent, requires at least 60 ml of PEG200, a temperature of 240 °C, and a reaction time of minimum 6 h. The samples were also analyzed by DLS and the hydrodynamic diameters of the IOMNPs were found between 400 and 800 nm, indicating that IOMNPs aggregate in aqueous solutions (Additional file 1: Figure S7 and Table S7), although the samples were treated with tetramethylammonium hydroxide (TMAOH) as discussed below. Thus, the application of DLS for further characterizing both the size and shape of IOMNPs is limited.Fig. 2


Polyethylene Glycol-Mediated Synthesis of Cubic Iron Oxide Nanoparticles with High Heating Power.

Iacovita C, Stiufiuc R, Radu T, Florea A, Stiufiuc G, Dutu A, Mican S, Tetean R, Lucaciu CM - Nanoscale Res Lett (2015)

TEM images (a, c) of water-soluble cubic and polyhedral IOMNPs obtained in 90 ml of PEG200 for 6- and 12-h reaction time and their corresponding size distribution histograms (b, d) fitted to a log-normal distribution (black line)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4596149&req=5

Fig2: TEM images (a, c) of water-soluble cubic and polyhedral IOMNPs obtained in 90 ml of PEG200 for 6- and 12-h reaction time and their corresponding size distribution histograms (b, d) fitted to a log-normal distribution (black line)
Mentions: Furthermore, the PEG200 volume was increased to 90 ml while keeping unchanged the reaction condition. In this case, the TEM images exhibited the coexistence of poly-dispersed cubic and polyhedral IOMNPs (Fig. 2a, c) with lower dimensions. As expected, the size of IOMNPs gradually increased with the reaction time. For instance, for a reaction time of 6 h at 240 °C, the IOMNPs have a mean size of 30 nm, whereas for 12 h, the mean size increases around 48 nm (Fig. 2b, d). No significant changes in the morphology and size were observed when the PEG200 volume was further increased to 120 ml. It is worth noting that we could not increase the reaction temperatures above 240 °C as PEG200 starts to boil. Also, below 240 °C, the nanoparticle synthesis cannot be performed. At the same time, for a reaction temperature of 240 °C, the synthesis can be completed only for reaction times longer than 6 h. Consequently, the formation of IOMNPs in the proposed solvothermal system, employing PEG200 as reducing agent, requires at least 60 ml of PEG200, a temperature of 240 °C, and a reaction time of minimum 6 h. The samples were also analyzed by DLS and the hydrodynamic diameters of the IOMNPs were found between 400 and 800 nm, indicating that IOMNPs aggregate in aqueous solutions (Additional file 1: Figure S7 and Table S7), although the samples were treated with tetramethylammonium hydroxide (TMAOH) as discussed below. Thus, the application of DLS for further characterizing both the size and shape of IOMNPs is limited.Fig. 2

Bottom Line: Iron oxide magnetic nanoparticles (IOMNPs) have been successfully synthesized by means of solvothermal reduction method employing polyethylene glycol (PEG200) as a solvent.The specific absorption rate (SAR) values increase with decreasing nanoparticle concentrations for the IOMNPs dispersed in water.By dispersing the IOMNPs in PEG600 (liquid) and PEG1000 (solid), it was found that the SAR values decrease by 50 or 75 %, indicating that the Brownian friction within the solvent was the main contributor to the heating power of IOMNPs.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical Physics-Biophysics, Faculty of Pharmacy, "Iuliu Hatieganu" University of Medicine and Pharmacy, Pasteur 6, 400349, Cluj-Napoca, Romania. cristian.iacovita@umfcluj.ro.

ABSTRACT
Iron oxide magnetic nanoparticles (IOMNPs) have been successfully synthesized by means of solvothermal reduction method employing polyethylene glycol (PEG200) as a solvent. The as-synthesized IOMNPs are poly-dispersed, highly crystalline, and exhibit a cubic shape. The size of IOMNPs is strongly dependent on the reaction time and the ration between the amount of magnetic precursor and PEG200 used in the synthesis method. At low magnetic precursor/PEG200 ratio, the cubic IOMNPs coexist with polyhedral IOMNPs. The structure and morphology of the IOMNPs were thoroughly investigated by using a wide range of techniques: TEM, XRD, XPS, FTIR, and RAMAN. XPS analysis showed that the IOMNPs comprise a crystalline magnetite core bearing on the outer surface functional groups from PEG200 and acetate. The presence of physisorbed PEG200 on the IOMNP surface is faintly detected through FT-IR spectroscopy. The surface of IOMNPs undergoes oxidation into maghemite as proven by RAMAN spectroscopy and the occurrence of satellite peaks in the Fe2p XP spectra. The magnetic studies performed on powder show that the blocking temperature (TB) of IOMNPs is around 300 K displaying a coercive field in between 160 and 170 Oe. Below the TB, the field-cooled (FC) curves turn concave and describe a plateau indicating that strong magnetic dipole-dipole interactions are manifested in between IOMNPs. The specific absorption rate (SAR) values increase with decreasing nanoparticle concentrations for the IOMNPs dispersed in water. The SAR dependence on the applied magnetic field, studied up to magnetic field amplitude of 60 kA/m, presents a sigmoid shape with saturation values up to 1700 W/g. By dispersing the IOMNPs in PEG600 (liquid) and PEG1000 (solid), it was found that the SAR values decrease by 50 or 75 %, indicating that the Brownian friction within the solvent was the main contributor to the heating power of IOMNPs.

No MeSH data available.


Related in: MedlinePlus