On the other hand knowledge of the chemical

On the other hand, knowledge of the chemical composition of the FeNP core is essential for the evaluation of these magnetic nanoparticles as targeted carriers of drugs. Depending on the details of the preparation method, different iron oxides can be present in the samples. Three of the most common are hematite (α-Fe2O3), maghemite (γ-Fe2O3), and magnetite (Fe3O4) [24]. Hematite is the most common iron oxide in nature because of its high thermodynamic stability, and maghemite is an important intermediate in hematite formation from the oxidation of magnetite precursors. Different studies [25–28] have demonstrated that Raman spectroscopy is a good tool for rapidly distinguishing iron oxides, hydroxides, and (oxy)hydroxides and, in our view, is a more powerful technique than X-ray diffraction. The Raman spectrum of hematite presents narrow bands at 225 (very strong), 247 (very weak), 292 (very strong), 411 (moderate), 496 (very weak), 610 (weak)cm−1. The Raman spectrum of magnetite presents an intense band at 668cm−1 and much smaller bands at 193, 306, and 538cm−1[29]. With regard to maghemite, the majority of authors take three broad maxima around 370, 500, and 710cm−1 as being indicative of maghemite.
We report here the development of multifunctional nanocarriers with a magnetic core and a biocompatible shell of buy HG-9-91-01 glycol (EG), with small amounts of folate and the anticancer agent cisplatin on the surface. These nanocarriers were synthesized in different ultrasonic fields (580, 861, and 1140kHz) and were characterized by different techniques.

Materials and methods

Results and discussion

Conclusions
We have developed a simple and direct route for the preparation of high performance FeNPs (nanocarriers) using ultrasound of different frequencies. These new multifunctional nanocarriers were composed of a magnetic core and a biocompatible shell (EG) with small amounts of cisplatin and folate. The sonochemical rate of oxidation of Fe2+ to Fe3+ was inversely proportional to the ultrasonic frequency, leading to an increased presence of Pt in the FeNPs. The mean size of the FeNPs was quasi-independent of frequency and the stabilizers forming the shell. The samples containing folate in the structure emitted a green fluorescence, a property that can be helpful for nanobiotechnological applications. All nanoparticles exhibited ferromagnetic characteristics at room temperature, with high Ms and low Hc and Mr values.

Acknowledgments

Introduction
In recent years, less-invasive ablative modalities using thermal energy, such as laser, focused ultrasound, microwave, and radiofrequency ablations, have received considerable attention, especially for localized tumor ablation [1–6]. To expand potential applications and avoid in vivo experiments or human experimentations, the design and processing of transparent tissue-mimicking phantoms capable of demonstrating the evolution and extent of thermal lesion formation in real time are extremely helpful for all ablative devices during preclinical development.
Several temperature-sensitive tissue-mimicking phantoms have been reported as model materials for ablative therapy. For example, polyvinyl alcohol (PVA) or agar-based phantoms were used to visualize the effect of bubble-enhanced heating by focused, MHz-frequency ultrasound [7]. However, thermal lesions could not be well visualized in such phantoms. Transparent polyacrylamide (PAA) gels containing bovine serum albumin (BSA) were then proposed since BSA would turn white and optically opaque or reduce the T2 signal on magnetic resonance imaging upon reaching the threshold temperature of protein denaturation [8–10]. Takegami et al. demonstrated a low-cost version by replacing BSA with egg white for the study of focused ultrasound ablation [11]. Although easily fabricated, the major disadvantages associated with egg white or albumin-based tissue-mimicking phantoms are the irreversible protein denaturation and permanent color change above the threshold temperature, making them impossible to be reused.