Potential Magnetic Resonance Imaging Contrast Agents Research Articles

Freeze-drying assisted sol–gel-derived silica-based particles embedding iron: synthesis and characterization

New silica-based particles embedding iron were synthesized following a freeze-drying-assisted sol–gel route. The samples were preliminary characterized in view of potential applications as theranostic magnetic resonance imaging (MRI) contrast agents and for hyperthermia treatment. The structural changes induced by iron addition were studied by X-ray diffraction, Fourier transform infrared and electron paramagnetic resonance spectroscopies. The addition of Fe2O3 impedes the SiO2 crystallization denoting that iron plays, in this case, the role of a glass network stabilizer. The composition on surface and nearby was analyzed by X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy both before and after samples immersion in simulated body fluid. The results suggest the nominal composition with 5 mol% Fe2O3 added to 0.7SiO2∙0.3Na2O matrix of interest for further investigations as potential MRI contrast agent and hyperthermia vector.

Mn(II) based T1 and T2 potential MRI contrast agent appended with tryptamine: Recognition moiety for Aβ-plaques

We report the synthesis and characterization of manganese(II) complexes having pentadentate ligands L1 (2,6-bis(1-(2-phenyl-2-(pyridin-2-yl)hydrazono)ethyl)pyridine), L2 (methyl 2,6-bis((E)-1-(2-phenyl-2-(pyridin-2yl)hydrazono)ethyl)isonicotinate), L3 (N-(2-(1H-indol-3-yl)ethyl)-2,6-bis((E)-1-(2-phenyl-2-(pyridin2yl)hydrazono)ethyl)isonicotiamide) and their application as dual contrast agents for simultaneous T1 and T2 weighted magnetic resonance imaging. Single crystal analysis of all the complexes [MnIIL1, MnIIL2 and MnIIL3] confirm the formation of novel seven-coordinate manganese complexes with an inner sphere water and perchlorate ion. The Magnetic Resonance Imaging (MRI) contrast agent [MnL2] was further modified by incorporating tryptamine as a binding moiety specific to Amyloid Beta-fibrils (Aβ-fibrils) in Alzhiemer's disease (AD) and it's in vitro evaluation for specific binding with Aβ-fibrils indicated as a bio-marker of AD.

Synthesis and study on magnetic resonance imaging performance of Gd(III)-DTPA-bisfuran-2-carbohydrazide as a potential MRI contrast agent

ABSTRACTOne novel ligand, diethylenetriamine-N, N“-bi(acetyl-furan-2-carbohydrazide)-N, N′, N”-triacetic acid (H3L), has been synthesized in high yield by the reaction of bicyclic anhydride of diethylenetraiaminepentaacetic acid (DTPA) with furan-2-carbohydrazide. It has three carboxylic groups, and the corresponding nonion complex of Gd(III)-L holding promise of magnetic resonance imaging (MRI) was obtained by treating these ligand with Gd2O3 in water. The efficacy of the contrast agent was assessed by measuring the longitudinal relaxivity (r1) and T1 weighted magnetic resonance imaging in vitro. The r1 of Gd(III)-DTPA-bisfuran-2-carbohydrazide was up to 5.92 mM−1·s−1, which was 1.27 times higher than that of the analogous MRI contrast agent Gd(III)-DTPA(4.65 mM−1·s−1) in clinical application. T1 weighted magnetic resonance imaging in vitro showed that proton signal intensity increased with Gd(III) complex concentration and the imaging effect of Gd(III)-DTPA-bisfuran-2-carbohydrazide was superior to that of Gd(III)-DTPA in the same condition. These results showed that the complex might be considered as a potential MRI contrast agent.

Synthetic Ni3S2/Ni hybrid architectures as potential contrast agents in MRI

Traditional magnetic resonance imaging (MRI) contrast agents mainly include superparamagnetic (SPM) iron oxide nanoparticle as T2 contrast agent for liver and paramagnetic Gd (III)-chelate as T1 contrast agent for all organs. In this work, weak ferromagnetic kale-like and SPM cabbage-like Ni3S2@Ni hybrid architectures were synthesized and evaluated as potential T1 MRI contrast agents. Their relatively small r2/r1 ratios of 2.59 and 2.38, and high r1 values of 11.27 and 4.89 mmol−1 L s−1 (for the kale-like and cabbage-like Ni3S2@Ni, respectively) will shed some light on the development of new-type MRI contrast agents.

Preparation of Amyloid Immuno-Nanoparticles as Potential MRI Contrast Agents for Alzheimer's Disease Diagnosis.

Alzheimer's disease (AD) is the most common form of dementia which is caused by accumulation in the brain of plaques made up of amyloid beta-peptide (Abeta). Research on nanosized systems indicated that nanoparticles (NPs) could pass across the blood-brain barrier (BBB) and improve the visibility of internal body structures in magnetic resonance imaging (MRI), which made it possible to aid the early diagnosis of AD. In this research study we synthesized magnetite nanoparticles by high-temperature solution-phase reaction, transferred into water based on a ligand exchange process and coated with meso-2,3-dimercaptosuccinic (DMSA). Subsequently, the anti-amyloid Abeta immunomagnetic nanoparticles (IMNPs) were prepared by grafting anti-amyloid antibodies on the surface of the DMSA-coated magnetic nanoparticles (MNPs). The enzyme linked immunosorbent assay (ELISA) method was introduced to evaluate the IMNPs activity and conjugation amount of antibodies. The biocompatibility of the IMNPs was tested by colony-forming assay. The results showed that the anti-amyloid Abeta IMNPs were biocompatible and biologically active, as well as effective in enhancing MRI solution, indicating that the IMNPs could be used as potential MRI contrast agents and targeted carriers for AD early diagnosis and therapy.

Magnetic properties, water proton relaxivities, and in-vivo MR images of paramagnetic nanoparticles

In this mini review, magnetic resonance imaging (MRI) contrast agents based on lanthanideoxide (Ln2O3) nanoparticles are described. Ln2O3 (Ln = Gd, Dy, Ho, and Er) nanoparticles are paramagnetic, but show appreciable magnetic moments at room temperature and even at ultrasmall particle diameters. Among Ln2O3 nanoparticles, Gd2O3 nanoparticles show larger longitudinal water proton relaxivity (r1) values than Gd-chelates because of the large amount of Gd in the nanoparticle, and the other Ln2O3 nanoparticles (Ln = Dy, Ho, and Er) show appreciable transverse water proton relaxivity (r2) values. Therefore, Gd2O3 nanoparticles are potential T1 MRI contrast agents while the other Ln2O3 nanoparticles are potential T2 MRI contrast agents at high MR fields.

A new biodegradable and biocompatible gadolinium (III) -polymer for liver magnetic resonance imaging contrast agent

A new biodegradable and biocompatible gadolinium (III) -copolymer (ACL-A2-DOTA-Gd) has been developed as a potential liver magnetic resonance imaging (MRI) contrast agent. ACL-A2-DOTA-Gd consisted of a poly (aspartic acid-co-leucine) unit bound with 1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid-gadolinium (Gd-DOTA) via the linkage of ethylenediamine. In vitro, the biodegradable experiment and cytotoxicity assay showed the biodegradability and biocompatibility of this gadolinium-polymer. ACL-A2-DOTA-Gd presented an increase in relaxivity of 2.4 times than the clinical Gd-DOTA. In vivo, gadolinium (III)-copolymer was mainly accumulated in the liver, and it could be excreted via the renal and hepatobiliary mechanism. The average enhancement of ACL-A2-DOTA-Gd (60.71±5.93%, 50–80min) in liver was 2.62-fold greater than that of Gd-DOTA (23.16±3.55%, 10–30min). ACL-A2-DOTA-Gd could be as a potential liver MRI contrast agent with a long time-window.

A Hyaluronic Acid-Chitosan-Gadolinium Nanosphere for Specific Tumor-Targeted MRI Contrast Agent

A hyaluronic acid-chitosan-gadolinium (HA-CTS-Gd) nanosphere is prepared by HA modified CTS nanosphere and the complexation between Gd ions and functional groups in CTS and HA molecule. The nanosphere is used as a novel magnetic resonance imaging (MRI) contrast agent for targeting specific tumor. The results show that the HA-CTS-Gd nanosphere is stable in physiological environment due to the strong Gd chelating interaction between the abundant functional groups in HA and chitosan molecules, which leads to low toxicity. Moreover, the obtained nanosphere reveals a high CD44 targeting efficiency and relaxation efficiency in vitro, and it has a great agency for human colonic and mouse lymphatic tumor MRI in vivo. Thus, the novel MRI contrast agent can be taken up selec- tively by CD44 antigen and used as a potential MRI contrast agents in specific tumor.

2, 3-Dimercaptosuccinic Acid-Modified Iron Oxide Clusters for Magnetic Resonance Imaging

Over the last decade, various magnetic nanomaterials have been developed as magnetic resonance imaging (MRI) contrast agents; the greatest challenges encountered for clinical application have been insufficient stability. In this paper, a lyophilization method for 2, 3-dimercaptosuccinic acid-modified iron oxide (γ-Fe2 O3 @DMSA) nanoparticles was developed to simultaneously overcome two disadvantages; these include insufficient stability and low-magnetic response. After lyophilization, the clusters of γ-Fe2 O3 @DMSA with the size of 156.7 ± 15.3 nm were formed, and the stability of the lyophilized powder (γ-Fe2 O3 @DMSA-LP) increased up to over 3 years. It was also found that rehydrated γ-Fe2 O3 @DMSA-LP could be ingested by RAW264.7 cells in very large quantities. Results of pharmacokinetics and biodistribution studies in vivo indicated that γ-Fe2 O3 @DMSA-LP is a promising liver-targeted material. Furthermore, it also exhibited higher MRI efficiency and longer imaging time in the liver than the well-known product Feridex(®) . Moreover, results of vascular irritation and long-term toxicity experiments demonstrated γ-Fe2 O3 @DMSA-LP could be a nontoxic, biocompatible contrast agent in vivo. Therefore, the proposed γ-Fe2 O3 @DMSA-LP can be used as a potential MRI contrast agent in clinic for hepatic diseases.

DYNAMIC MR IMAGING, BIODISTRIBUTION AND PHARMACOKINETICS OF POLYMER SHELLED MICROBUBBLES CONTAINING SPION

Magnetic Resonance Imaging (MRI) is a noninvasive diagnostic method that provides information on morphological and physiological changes of the internal organs over time. Imaging and measurements can be repeated on the same subject, thereby reducing inter-individual variability effects and hence the number of subjects required. A potential MRI contrast agent consisting of microbubbles embedded with superparamagnetic iron oxide nanoparticles (SPION) in the shell (SPION MBs) was injected intravenously into rats to determine their biodistribution and pharmacokinetics using MR imaging. Agarose phantoms containing SPION MBs were scanned using 3 T MRI to construct a standard curve. Rats were injected with SPION MBs, free SPION or plain MBs and scanned dynamically at 3 T using a clinical MR scanner. The relaxation rate (R2*) was studied over time as a measure of the iron oxide concentrations to enable calculation of the pharmacokinetic parameters. The kinetics of SPION MBs in the liver was fitted to a one-compartment model. Furthermore, the biological fate of SPION MBs was examined via a histological survey of tissue samples using Perls' Prussian blue staining and immunohistochemistry (IHC). 1.2 h after injection of SPION MBs, T2* of the liver had decreased to its minimum. The elimination half-life of SPION MBs was 598.2 ± 97.3 h, while the half-life for SPION was 222.6 ± 26.4 h. Moreover, our study showed that SPION MBs were taken up by the macrophages in the lungs, spleen and liver. MBs labeled with SPION can be used for MR imaging. Moreover, MRI is a reliable and noninvasive tool that can be utilized in pharmacokinetic investigations of future contrast agents using SPION MBs and SPION in the rat.

Synthesis and in vitro evaluation of manganese(II)-porphyrin modified with chitosan oligosaccharides as potential MRI contrast agents

Mn-TCPP-CS n (n=6, 11, 20) as a type of potential magnetic resonance imaging(MRI) contrast agents were synthesized via manganese(II) meso-tetra(4-carboxyphenyl) porphyrin(Mn-TCPP) modified with chitosan oligosaccharides(CS n ). Experimental data of infared(IR), UV-Vis, MS, inductively coupled plasma-atomic emission spectrometer(ICP-AES) and size exclusion chromatography evidenced the formation of Mn-TCPP-CS n . The stability results show that Mn-TCPP-CS n in aqueous solution was stable enough to prevent Mn(II) ions from leaking. The magnetic properties in vitro indicate that Mn-TCPP-CS20 possesses higher longitudinal relaxivity(r 1=10.38 L·mmol−1·s−1) in aqueous solution than unmodified porphyrin Mn-TCPPNa4[manganese(II) meso-tetra(4-carboxyphenyl) porphyrin, tetrasodium salt](r 1=5.10 L·mmol−1·s−1) and the commercial contrast agent Gd-DTPA(r 1=4.05 L·mmol−1·s−1). The preliminary T 1-weighted flash image studies in vitro show that the contrast and the imaging signal of Mn-TCPP-CS n were superior to those of Mn-TCPPNa4 and Gd-DTPA under the same conditions. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay shows that Mn-TCPP-CS n has a good biocompatibility. In addition, the thermodynamical parameters(ΔH<0, ΔS<0, ΔG<0) of Mn-TCPP-CS n bound to bovine serum albumin(BSA) show that Mn-TCPP-CS n could bind to BSA spontaneously, where the binding complex was stabilized mainly by van der Waals interactions and hydrogen bonds. These results suggest that Mn-TCPP-CS n have the advantage of becoming a potential MRI contrast agent.

Bovine serum albumin (BSA) and cleaved-BSA conjugated ultrasmall Gd2O3 nanoparticles: Synthesis, characterization, and application to MRI contrast agents

Bovine serum albumin (BSA) (Mn=66.5kD, size=14×4×4nm) is an attractive biological molecule for biomedical applications because of its water-solubility and bio-compatibility. It can also bind many ultrasmall nanoparticles (NPs) as confirmed in this study. We synthesized polyethylene glycol diacid (PEGD) coated ultrasmall Gd2O3 nanoparticles (PEGD-GNPs, the core davg=2.0nm), which were then conjugated to BSA and cleaved-BSA (C-BSA) (i.e. BSA-PEGD-GNPs and C-BSA-PEGD-GNPs) through amide bonding. Large relaxivities were observed in both aqueous sample solutions (r1=6.0s−1mM−1 and r2=28.0s−1mM−1 for BSA-PEGD-GNPs and r1=7.6s−1mM−1 and r2=22.0s−1mM−1 for C-BSA-PEGD-GNPs). Three tesla T2 magnetic resonance imaging (MRI) in a mouse after the injection of an aqueous sample solution of BSA-PEGD-GNPs into a mouse tail vein revealed significant negative contrast enhancements. Large relaxivities and in vivo MR images prove that BSA-PEGD-GNPs and C-BSA-PEGD-GNPs are potential MRI contrast agents.

Nanoassemblies of Gd-DTPA-monooleyl and glycerol monooleate amphiphiles as potential MRI contrast agents.

Self-assembly of lipid-based amphiphiles into various supramolecular nanostructured particles has been used in creating novel nanomaterials with diverse applications in drug delivery and diagnostic imaging. Here we report on Gd(iii) chelated DTPA amphiphiles with an oleyl chain (Gd-DTPA-MO) incorporated within the self-assembly matrix of glycerol monooleate (GMO), an inverse cubic phase forming system, at varying compositions. The dispersed colloidal nanoassemblies were explored for their potential as magnetic resonance imaging (MRI) contrast agents. We investigated the homogeneity of the mixed amphiphiles in bulk phases by differential scanning calorimetry (DSC) and their lyotropic phase behaviour by synchrotron small angle X-ray scattering (SAXS). The liquid crystalline nanostructures, morphology and the size distribution of the nanoassemblies were studied by synchrotron SAXS, cryogenic transmission electron microscopy (cryo-TEM) and dynamic light scattering (DLS). SAXS and cryo-TEM results revealed the formation of inverse cubosomes in dispersions with ≤1 mol% of Gd-DTPA-MO, and liposomal and rod-shaped micellar aggregates with >1 mol%. The stability of cubosomal nanoassemblies was assessed in the presence of fetal bovine serum, showing minimal effect on their nanostructures. In vitro relaxivity studies were performed at four different magnetic field strengths (0.54, 7.05, 9.40 and 11.74 T). All the colloidal dispersions displayed enhanced longitudinal relaxivities per Gd over Magnevist, a commercially available contrast agent, at both low and high magnetic field strengths. In addition, cubosomes with 3D-periodic interior nanostructures, extensive water channels and high interfacial surface area, showed promise as high field contrast agents. These stable colloidal particles also have potential to be used as combined delivery matrices for diagnostics and therapeutics (theranostics).

PH-responsive star polymer nanoparticles: potential 19F MRI contrast agents for tumour-selective imaging

Star polymers with a branched core and hydrophilic arms were synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization as pH-responsive 19F magnetic resonance imaging (MRI) agents. The branched core consists of 2,2,2-trifluoroethyl acrylate (TFEA, providing 19F MRI signal) and 2-(dimethylamino)ethyl methacrylate (DMAEMA, offering pH-responsive properties). The arms are comprised of poly(poly(ethylene glycol) methyl ether methacrylate) (PPEGMA) brushes that form hydrophilic and biocompatible shells around the cores. The structure and composition of the star polymers were characterised in detail. Nanoparticles were fabricated by direct dissolution of the star polymers in aqueous solution. 19F nuclear magnetic resonance (19F NMR) revealed that the 19F signal intensity and spin–spin relaxation time (T2) were significantly dependent on the pH of polymer solution, while the 19F spin-lattice (T1) relaxation time remained constantly low at ∼450 ms upon increasing the pH above the pKa of the DMAEMA groups. A dramatic change in 19F MRI imaging intensity was observed on passing from an alkaline to an acidic environment. These results indicate that these 19F detectable and pH-sensitive star polymer nanoparticles are promising as 19F MRI “smart” contrast agents for selective imaging.

Gadolinium chelate with DO3A conjugated 2-(diphenylphosphoryl)-ethyldiphenylphosphonium cation as potential tumor-selective MRI contrast agent

A series of organic cations, such as triphenylphosphonium (TPP), 2-(diphenylphosphoryl)-ethyldiphenylphosphonium (TPEP), represent molecular probes for imaging tumors. These organic cations have been labeled with 64Cu radioisotope for imaging tumors by positron emission tomograghy (PET). Among these organic cation ligands, TPEP was selected for extensive evaluation using magnetic resonance imaging (MRI) based on its higher tumor uptake and better Tumor/Background (T/B) ratios. This report presents the development of a new Gd(III) chelate [Gd(DO3A-xy-TPEP)]+ as a cationic MRI contrast agent. The contrast agent was synthesized and characterized in vitro and in vivo. In vitro cell viability showed low cytotoxicity at low [Gd] concentrations. Cell uptake experiment shows that the [Gd(DO3A-xy-TPEP)]+ has high affinity for tumor cells. The in vitro T1 relaxivity measured at 9.4 T is about 50% higher than those of contrast agents in clinical use: Gd-DTPA (Magnevist) and Gd-DOTA (Dotarem). In vivo imaging studies in tumor-bearing mice at 7.0 T demonstrated significant signal enhancement at the site of the tumors. [Gd(DO3A-xy-TPEP)]+ is a promising tumor-targeting MRI contrast agent for diagnostic imaging.

The effect of poly(ethylene glycol) coating on colloidal stability of superparamagnetic iron oxide nanoparticles as potential MRI contrast agent

Superparamganetic iron oxide-based contrast agents in magnetic resonance imaging (MRI) have offered new possibility for early detection of lymph nodes and their metastases. According to important role of nanoparticle size in biodistribution, magnetite nanoparticles coated with different polyethylene glycol (PEG) concentrations up to 10/1 PEG/iron oxide weight ratio in an ex situ manner. To predict the PEG-coated nanoparticle behavior in biological media, such as blood stream or tissue, colloidal stability evaluation was performed to estimate the coating endurance in different conditions. Accordingly, optical absorbance measurements were conducted in solutions with different values of pH and NaCl concentrations. The results indicated that at neutral pH condition, nanoparticles treated by 3/1 ratio possessed better stability parameters. Investigating at high pH of 10 resulted in superior stability for bare magnetite nanoparticles due to its higher electrophoretic mobility. Coating material was attacked at acidic solutions which cause samples with higher PEG weight ratio to be settled slower. In various ionic strengths of 10−5 to 0.1M, 3/1 ratio samples offered greater resistivity to sedimentation. The nanoparticles were further investigated by exposure to L929 cell and following up the iron uptake within cells. Finally, detection sensitivities in lymph nodes were evaluated. Particle uptake and the most signal reduction for in vivo MRI studies were also obtained by nanoparticles acquiring lower PEG contents that showed better colloidal stability.

Characterization of quaternized chitosan‐stabilized iron oxide nanoparticles as a novel potential magnetic resonance imaging contrast agent for cell tracking

AbstractPolymer‐stabilized iron oxide nanoparticles could be used as contrast agents in magnetic resonance imaging (MRI) due to their unique superparamagnetism. Here we demonstrate a quaternized chitosan, i.e. N‐[(2‐hydroxy‐3‐trimethylammonium)propyl] chitosan chloride (HTCC), encapsulating superparamagnetic iron oxide (SPIO), with very low toxicity and less effect on cell growth. HTCC has quaternary amino groups introduced into the chitosan chain, and such modification of chitosan should render it soluble in water. Most importantly, the HTCC–SPIO thus prepared has the ability to accelerate the MRI relaxation processes of surrounding water protons, resulting in enhanced MRI contrast (R2: y = 0.1076x − 0.0092; R1: y = 0.008x − 0.0005). The iron content quantified by Prussian blue staining and MRI revealed a positive correlation between Prussian blue positive cells and the change of MRI signal intensity. Also, transmission electron microscopy and element mapping confirmed intracellular metal‐like spots as internalized iron oxide. Such findings support the use of these quaternized chitosan‐stabilized iron oxide nanoparticles as a potential MRI contrast agent for cell tracking. Copyright © 2011 Society of Chemical Industry

Design and synthesis of novel DOTA(Gd3+)–polymer conjugates as potential MRI contrast agents

Conventional low molecular weight gadolinium based Magnetic Resonance Imaging (MRI) contrast agents such as Magnevist® are very useful for imaging tissues. However, at the high magnetic fields used in modern MRI equipments, their relaxivity (contrasting efficiency) is rather poor. The grafting of the gadolinium complex onto macromolecules is a way to enhance their relaxivity provided that the rotational motion of the complex is decreased significantly. Here we report the design of novel Gd3+ based MRI contrast agents with improved relaxivity and potential long blood circulation life-time. We investigate the grafting of 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid, 1,4,7-tris(1,1-dimethylethyl) ester (DO3AtBu-NH2; a precursor of Gd3+ ligand) onto well-defined functional copolymers bearing activated esters (succinimidyl esters) and poly(ethylene oxide) (PEO) chains required for stealthiness. The tert-butyl groups of grafted DO3AtBu-NH2 are then deprotected by trifluoroacetic acid followed by complexation of Gd3+. Addition of free DOTA at the end of the reaction is necessary to leave the pure and stable water soluble macrocontrast agent. Importantly it shows a relaxivity at high frequencies that is 300% higher than that of the ungrafted gadolinium complex. These novel functional copolymers are therefore promising candidates as macromolecular contrast agents for MRI applications.

Strategies for the covalent conjugation of a bifunctional chelating agent to albumin: Synthesis and characterization of potential MRI contrast agents

With the purpose to develop macromolecular magnetic resonance imaging contrast agents, we herein report three different synthetic approaches to the covalent attachment of bifunctional chelating agents to human serum albumin followed by coordination to contrast enhancing gadolinium(III). Applied methods cover active ester-mediated conjugation, linkage through glutaryl spacer, as well as the connection by the employment of glutaraldehyde. The content of gadolinium(III) was evaluated by inductively-coupled-plasma mass-spectrometry (ICP-MS) measurements and indicated reproducible amounts of conjugated contrast enhancing material. Small angle X-ray scattering (SAXS) experiments provided the size and altered shape of the gadolinium loaded proteins in comparison to unmodified albumin. Finally, the magnetic resonance properties of the protein conjugates were evaluated. The results indicated suitability of the gadolinium(III) loaded protein conjugates for use as macromolecular contrast agents in magnetic resonance imaging (MRI).

Synthesis, self-assembly, and characterization of PEG-coated iron oxide nanoparticles as potential MRI contrast agent

Aim: Investigated the self-assembly and characterization of novel antifouling polyethylene glycol (PEG)-coated iron oxide nanoparticles as nanoprobes for magnetic resonance imaging (MRI) contrast agent. Method: Monodisperse oleic acid-coated superparamagnetic iron oxide cores are synthesized by thermal decomposition of iron oleate. The self-assembly behavior between iron oxide cores and PEG-lipid conjugates in water and their characteristics are confirmed by transmission electron microscope, X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, and vibrating sample magnetometer. Result: Dynamic light scattering shows superparamagnetic iron oxide nanoparticles coated with PEG are stable in water for pH of 3–10 and ionic strengths up to 0.3 M NaCl, and are protein resistant in physiological conditions. Additionally, in vitro MRI study demonstrates the efficient magnetic resonance imaging contrast characteristics of the iron oxide nanoparticles. Conclusion: The result indicates that the novel antifouling PEG-coated superparamagnetic iron oxide nanoparticles could potentially be used in a wide range of applications such as biotechnology, MRI, and magnetic fluid hyperthermia.