Integration of PEG-conjugated gadolinium complex and superparamagnetic iron oxide nanoparticles as T1–T2 dual-mode magnetic resonance imaging probes

Abstract

The T1−T2 dual-mode probes for magnetic resonance imaging (MRI) can non-invasively acquire comprehensive information of different tissues or generate self-complementary information of the same tissue at the same time, making MRI a more flexible imaging modality for complicated applications. In this work, three Gadolinium-diethylene-triaminepentaaceticacid (Gd-DTPA) complex conjugated superparamagnetic iron oxide (SPIO) nanoparticles with different Gd/Fe molar ratio (0.94, 1.28 and 1.67) were prepared as T1–T2 dual-mode MRI probes, named as SPIO@PEG-GdDTPA0.94, SPIO@PEG-GdDTPA1.28 and SPIO@PEG-GdDTPA1.67, respectively. All SPIO@PEG-GdDTPA nanocomposites with 8 nm spherical SPIO nanocrystals showed good Gd3+ chelate stability. SPIO@PEG-GdDTPA0.94 nanocomposites with lowest Gd/Fe molar ratio show no cytotoxicity to Raw 264.7 cells as compared to SPIO@PEG-GdDTPA1.28 and SPIO@PEG-GdDTPA1.67. SPIO@PEG-GdDTPA0.94 nanocomposites with r1 (8.4 mM−1s−1), r2 (83.2 mM−1s−1) and relatively ideal r2/r1 ratio (9.9) were selected for T1–T2 dual-mode MRI of blood vessels and liver tissue in vivo. Good contrast images were obtained for both cardiovascular system and liver in animal studies under a clinical 3 T scanner. Importantly, one can get high-quality contrast-enhanced blood vessel images within the first 2 h after contrast agent administration and acquire liver tissue anatomy information up to 24 h. Overall, the strategy of one shot of the dual mode MRI agent could bring numerous benefits not only for patients but also to the radiologists and clinicians, e.g. saving time, lowering side effects and collecting data of different organs sequentially.

PEGylated amphiphilic polymeric manganese(ii) complexes as magnetic resonance angiographic agents

“…Besides, due to the size-effect of mPEG 2k -P(MnL-a-HMDI)-mPEG 2k micelles and the modification of PEG that slows the opsonization effect, it reduced kidney clearance, and also slows down the endocytosis by RES, and therefore prolongs the blood circulation time. 43,47,48 As shown in the Fig. 7a, mPEG 2k -P(MnL-a-HMDI)-mPEG 2k micelles can still provide the vascular structure images after 150 minutes of administration at a relatively lower Mn dosage (0.05 mmol kg −1 BW) compared to the suggested clinical dosage (0.1 mmol kg −1 BW), 49,50 prolonging the observation window remarkably.…”

“…On the other hand, mPEG 2k -P(MnL-a-HMDI)-mPEG 2k generated more significant liver signal enhancement even after 24 hours of administration, attributing to its long blood circulation time and uptake by the RES organ. 48…”

Recent advances in regenerative biomaterials

“…Nanoceria is able to form more oxygen vacancies because the decreased surface area to volume ratio. Besides, some rare-earth metal-based materials have the magnetic properties, which can be used in magnetic resonance imaging (MRI), such as gadolinium [ 69 ], holmium and dysprosium [ 70 ].…”

Ferritin: A Promising Nanoreactor and Nanocarrier for Bionanotechnology

“…Under the influence of external magnetic field, these particles can be utilized for the treatment of malignant tissues/organs owing to their easy binding and bioconjugation to proteins, drugs, and antibodies for targeted delivery applications. , Nevertheless, the agglomeration of such nanoparticles owing to their high surface area to volume ratio, which compels them to reduce their energy via aggregation, emerges as one of the major limitations in their usage and applicability. Therefore, efforts have been made to stabilize the nanoparticles by employing various protection strategies in the form of organic or inorganic layer coatings, , surfactant or polymer coatings, , or biomolecular templating, , etc. Earlier reports have suggested the use of biomolecule-based supramolecular templates which are both genetically and chemically modified with metal binding ligands for the synthesis of stable, monodispersed encapsulated nanoparticles.…”