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Published in Valerio Voliani, Nanomaterials and Neoplasms, 2021
Nohyun Lee, Seung Hong Choi, Taeghwan Hyeon
Materials based on lanthanides with high atomic numbers can also be used as CT contrast agents [5]. Among the lanthanides, gadolinium has been most intensively studied for biomedical applications because it is also used as a T1 MRI contrast agent due to its paramagnetic property [106]. Since free lanthanide ions are very toxic, chelating agents such as diethylenetriamine pentaacetic acid (DTPA) and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) are employed to reduce the toxicity, and several Gd-chelates are approved by the FDA. However, most FDA-approved lanthanide complexes are renally excreted, thus their circulation times are very short. In an early evaluation of CT contrast effects of lanthanides, it was shown that the X-ray absorption of Gd-DTPA and Yb-DTPA was higher than that of iodine at 120 kV and 137 kV [107]. When these agents were administered intravenously in dogs, the signal of the aorta reached a maximum at 15 s after injection and then rapidly decreased owing to short circulation times.
Carbon Encapsulated Functional Magnetic Nanoparticles for Life Sciences
Published in Paweł K. Zarzycki, Pure and Functionalized Carbon Based Nanomaterials, 2020
Clara Marquina, M. Ricardo Ibarra
A more accurate calculation of the nanoparticles accumulated in each organ could be done by taking images of phantoms in which a known quantity of nanoparticles had been injected and using the intensity of the signal obtained for further calibration. However, this was beyond the scope of the study presented here. The results obtained showed that the MRI technique is an excellent tool to study the distribution of magnetic nanoparticles within an organism and the evolution of this distribution along the time. In addition, these experiments proved that Fe@C nanoparticles create a high enough contrast in MRI images, and therefore Fe@C biocompatible fluids could be used as a contrast agent. First of all, it will be desirable to improve the quality of the suspensions in order to avoid the nanoparticles being cleared from the circulatory system by the macrophages, and therefore increase the residence time of the nanoparticles in blood. Secondly, a detailed study of the suspension relaxivity by Time Domain NMR in vitro experiments will be also necessary to assess the effectiveness of the magnetic biocompatible fluid as contrast agent. The nanoparticles could be conjugated with a biomolecule of interest (an antibody, tumor marker receptor, etc.) linked to their coating. This would allow the specificity of the MRI contrast agent for a particular organ or tumor marker. Moreover, making use of the capability of storing a chemotherapy drug adsorbed onto the carbon coating, as seen in a previous section, confers the nanoparticles a multifunctional character, making them useful for both diagnosis and therapy.
Stimuli-Regulated Cancer Theranostics Based on Magnetic Nanoparticles
Published in Nguyễn T. K. Thanh, Clinical Applications of Magnetic Nanoparticles, 2018
Yanmin Ju, Shiyan Tong, Yanglong Hou
Single modality contrast agents all have advantages and disadvantages. For example, Gd-based T1 positive MRI contrast agents have brighter excellent images with risks of biological toxicity.106 MNP-based T2-weighted MRI contrast agents have low toxicity to the human body, while the resulting dark signal might mislead the clinical diagnosis as their negative contrast is easily confused with a low level MR signal tissues such as bone or vasculature.107 Therefore, the development of new types of MR contrast agents with robust dual MRI contrast agents is urgently needed as well. The dual T1- and T2-weighted MRI contrast agent significantly improve detection accuracy for molecular imaging and diagnostic application.108,109 Hu et al. synthesized 5.4 nm SPIONs of high crystallinity and size uniformity for dual contrast T1- and T2-weighted MRI. The SPIONs exhibit an impressive magnetization of 94 emu/g Fe3O4, the highest r1 of 19.7 mM–1s–1 and the lowest r2/r1 ratio of 2.0 at 1.5 T. T1- and T2-weighted MR images showed that the SPIONs can improve surrounding water proton signals in the T1-weighted image and induce significant signal reduction in the T2-weighted image. In vitro cell experiments demonstrated that the SPIONs have little effect on the viability of tumour cell.110
A review on magnetic polymeric nanocomposite materials: Emerging applications in biomedical field
Published in Inorganic and Nano-Metal Chemistry, 2023
Magnetically guided drug targeting using magnetic nanoparticles and nanocomposites is a promising approach for cancer chemotherapy and diagnosis. The use of biocompatible magnetic nanocomposites as drug or gene delivery systems can contribute to the effectiveness of cancer therapy in many ways. Magnetic nanocomposites are used in diagnosis by MRI and sensing, treatment by drug delivery and gene targeting, and prevention by vaccination and heat delivery by hyperthermia. Among the broad spectrum of nano biomaterials under investigation for cancer comprehensive treatment, magnetic nanocomposite materials have gained significant attention due to their unique features which are not present in other materials. In particular, superparamagnetic particles are the preferred ones. SPIONs find applications in cancer treatment,[210–214] tissue repair,[215] and magnetic cell sorting.[216,217] One of the most intriguing applications of SPIONs is as an MRI contrast agent for cancer diagnosis. The early detection of tumor/cancer markers in blood or tissue provides easy disease diagnosis, disease recurrence, and treatment for long-term survival of cancer patients.
The soft congeries fabricated by micelles in colloid solution for T 1 magnetic resonance imaging contrast agent
Published in Soft Materials, 2021
Wen Li, Danxiu Dong, Jinxuan Zou, Huiqiang Zhao, Weilu Zhang
To know better the potentials of PAMAM[AEO/(DBSA-Gd)] as micellar congeries MRI contrast agent, their relaxation rates were measured on magnetic field intensity of 0.5 Tesla (T). T1-weighted MR images of the PAMAM[AEO/(DBSA-Gd)] were shown in Figure 5. T1 is the value of spin-lattice relaxation time. The contrast effect and the relaxitivity values both showed a tendency to increase with the increasing of concentrations PAMAM[AEO/(DBSA-Gd)] as showed in Fig.5. The signal intensity of PAMAM[AEO/(DBSA-Gd)] had better contrast imaging at a lower concentration of 5.0 mmol·L−1 (mM) even on 0.5 T when the relaxitivity (r1) was 10.56 mM−1·s−1. The results were contributed to the enrichment of Gd ions in their core, and also meant much lower dosage of PAMAM[AEO/(DBSA-Gd)] should be used for obtaining the same MR image in clinic application, suggestion of their potentials as MRI contrast agents.
Nanocomposites of ferroelectric liquid crystals and FeCo nanoparticles: towards a magnetic response via the application of a small electric field
Published in Liquid Crystals, 2020
Patricio N. Romero-Hasler, Lynn K. Kurihara, Lamar O. Mair, Irving N. Weinberg, E. A Soto-Bustamante, L. J. Martínez-Miranda
We are interested in generating a magnetic field with an electric field of 20V/m, and to have a magnetic field that will be detected by an MRI instrument. We report on a study performed on a nanocomposite of the ferroelectric 2-(4-((2-fluorooctyl)oxy)phenyl)-5-(octyloxy)pyrimidine, mixed with FeCo magnetic nanoparticles. The nanoparticles have an average size of 2.5–3.5 nm, and are functionalised with polyethelene glycol (PEG) [31]. Three concentrations of FeCo are examined: 0.56, 4.35 and 10.8 wt %. We begin to observe the re-alignment of the clusters at fields as low as 5V/cm. The re-alignment seems to saturate at 104V/cm for a concentration of 10.8 wt % of the FeCo in the ferroelectric liquid crystal. We find it takes a small applied electric field to begin to align the nanoparticles. The magnetic response to an applied electric field can be applied to an MRI contrast agent. This can been done by encapsulating the nanocomposite, such that it can be easily introduced and removed from the body [48]. Our purpose is: 1. to reduce the applied electric field that produces the required magnetic field down to the electric fields produced by biological systems, 2. while keeping the concentration of nanoparticles relatively low.