One-step, room-temperature synthesis of glutathione-capped iron-oxide nanoparticles and their application in in vivo T1-weighted magnetic resonance imaging

Advances in the Optimization of Fe Nanoparticles: Unlocking Antifungal Properties for Biomedical Applications

In recent years, nanotechnology has achieved a remarkable status in shaping the future of biological applications, especially in combating fungal diseases. Owing to excellence in nanotechnology, iron nanoparticles (Fe NPs) have gained enormous attention in recent years. In this review, we have provided a comprehensive overview of Fe NPs covering key synthesis approaches and underlying working principles, the factors that influence their properties, essential characterization techniques, and the optimization of their antifungal potential. In addition, the diverse kinds of Fe NP delivery platforms that command highly effective release, with fewer toxic effects on patients, are of great significance in the medical field. The issues of biocompatibility, toxicity profiles, and applications of optimized Fe NPs in the field of biomedicine have also been described because these are the most significant factors determining their inclusion in clinical use. Besides this, the difficulties and regulations that exist in the transition from laboratory to experimental clinical studies (toxicity, specific standards, and safety concerns) of Fe NPs-based antifungal agents have been also summarized.

Exceedingly Small Magnetic Iron Oxide Nanoparticles for T1 -Weighted Magnetic Resonance Imaging and Imaging-Guided Therapy of Tumors

Magnetic iron oxide nanoparticles (MIONs) based T2 -weighted magnetic resonance imaging (MRI) contrast agents (CAs) are liver-specific with good biocompatibility, but have been withdrawn from the market and replaced with Eovist (Gd-EOB-DTPA) due to their inherent limitations (e.g., susceptibility to artifacts, high magnetic moment, dark signals, long processing time of T2 imaging, and long waiting time for patients after administration). Without the disadvantages of Gd-chelates and MIONs, the recently emerging exceedingly small MIONs (ES-MIONs) (<5 nm) are promising T1 CAs for MRI. However, there are rare review articles focusing on ES-MIONs for T1 -weighted MRI. Herein, the recent progress of ES-MIONs, including synthesis methods (the current basic synthesis methods and improved methods), surface modifications (artificial polymers, natural polymers, zwitterions, and functional protein), T1 -MRI visual strategies (structural remodeling, reversible self-assemblies, metal ions doped, T1 /T2 dual imaging modes, and PET/MRI strategy), and imaging-guided cancer therapy (chemotherapy, gene therapy, ferroptosis therapy, photothermal therapy, photodymatic therapy, radiotherapy, immuotherapy, sonodynamic therapy, and multimode therapy), is summarized. The detailed description of synthesis methods and applications of ES-MIONs in this review is anticipated to attract extensive interest from researchers in different fields and promote their participation in the establishment of ES-MIONs based nanoplatforms for tumor theranostics.

Diagnostic and therapeutic roles of iron oxide nanoparticles in biomedicine

Nanotechnology changed our understanding of physics and chemics and influenced the biomedical field. Iron oxide nanoparticles (IONs) are one of the first emerging biomedical applications of nanotechnology. The IONs are composed of iron oxide core exhibiting magnetism and coated with biocompatible molecules. The small size, strong magnetism, and biocompatibility of IONs facilitate the application of IONs in the medical imaging field. We listed several clinical available IONs including Resovist (Bayer Schering Pharma, Berlin, Germany) and Feridex intravenous (I.V.)/Endorem as magnetic resonance (MR) contrast agents for liver tumor detection. We also illustrated GastroMARK as a gastrointestinal contrast agent for MR imaging. Recently, IONs named Feraheme for treating iron-deficiency anemia have been approved by the Food and Drug Administration. Moreover, tumor ablation by IONs named NanoTherm has also been discussed. In addition to the clinical application, several potential biomedical applications of IONs including cancer-targeting capability by conjugating IONs with cancer-specific ligands, cell trafficking tools, or tumor ablation agents have also been discussed. With the growing awareness of nanotechnology, further application of IONs is still on the horizon that would shed light on biomedicine.

DAT and PRX1 gene expression modulates vincristine production in Catharanthus roseus L. propagates using Cu, Fe and Zn nano structures

Underlying mechanism of nanostructures upon monoterpene induction in Catharanthus roseus has not been explored yet. In the current study, Copper, Iron and Zinc nanoparticles were biosynthesized by Eriobotrya japonica seed extract and capped with reduced glutathione. Biosynthesized nanoparticles and their capped analogues were characterized by UV-visible spectrophotometer, FTIR, XRD and SEM. Selected concentration of nanostructures were used in plant tissue culture media which instigated the production of alkaloids, tannins and flavonoids without significantly affecting the growth index of propagated calli and shoots cultures of C. roseus. Accelerated vincristine production was noticed in propagated calli and shoots under copper and zinc nanostress (1645-1865 μg/ml respectively) with the least effect by iron nanostructure. Highest concentration of calcium was recorded in in vitro shoots under capped (3.42 mg/ml ± 7.16) and uncapped (4.41 mg/ml ± 20.44) Zn nanoparticles compared to control (2.82 mg/ml ± 13.41). Real time PCR depicts nano-zinc mediated increased expression of DAT and PRX1 genes of TIA pathway. Significant correlation among PRX1/DAT gene expression with vincristine production and calcium accumulation in the presence of nanostress validate by PCA. This study paved way the opportunities of metal biogenic nanomaterials as an ideal drug modulator in plant tissue culture studies.

Ultrasmall superparamagnetic iron oxide nanoparticles: A next generation contrast agent for magnetic resonance imaging

As a research hotspot, the development of magnetic resonance imaging (MRI) contrast agents has attracted great attention over the past decades for improving the accuracy of diagnosis. Ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles with core diameter smaller than 5.0 nm are expected to become a next generation of contrast agents owing to their excellent MRI performance, long blood circulation time upon proper surface modification, renal clearance capacity, and remarkable biosafety profile. On top of these merits, USPIO nanoparticles are used for developing not only T₁ contrast agents, but also T₂ /T₁ switchable contrast agents via assembly/disassembly approaches. In recent years, as a new type of contrast agents, USPIO nanoparticles have shown considerable applications in the diagnosis of various diseases such as vascular pathological changes and inflammations apart from malignant tumors. In this review, we are focusing on the state-of-the-art developments and the latest applications of USPIO nanoparticles as MRI contrast agents to discuss their advantages and future prospects. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.

Magnetic Nanomaterials as Contrast Agents for MRI

Magnetic Resonance Imaging (MRI) is a powerful, noninvasive and nondestructive technique, capable of providing three-dimensional (3D) images of living organisms. The use of magnetic contrast agents has allowed clinical researchers and analysts to significantly increase the sensitivity and specificity of MRI, since these agents change the intrinsic properties of the tissues within a living organism, increasing the information present in the images. Advances in nanotechnology and materials science, as well as the research of new magnetic effects, have been the driving forces that are propelling forward the use of magnetic nanostructures as promising alternatives to commercial contrast agents used in MRI. This review discusses the principles associated with the use of contrast agents in MRI, as well as the most recent reports focused on nanostructured contrast agents. The potential applications of gadolinium- (Gd) and manganese- (Mn) based nanomaterials and iron oxide nanoparticles in this imaging technique are discussed as well, from their magnetic behavior to the commonly used materials and nanoarchitectures. Additionally, recent efforts to develop new types of contrast agents based on synthetic antiferromagnetic and high aspect ratio nanostructures are also addressed. Furthermore, the application of these materials in theragnosis, either as contrast agents and controlled drug release systems, contrast agents and thermal therapy materials or contrast agents and radiosensitizers, is also presented.

Iron Oxide Nanoparticles: An Alternative for Positive Contrast in Magnetic Resonance Imaging

Iron oxide nanoparticles have been extensively utilised as negative (T2) contrast agents in magnetic resonance imaging. In the past few years, researchers have also exploited their application as positive (T1) contrast agents to overcome the limitation of traditional Gd3+ contrast agents. To provide T1 contrast, these particles must present certain physicochemical properties with control over the size, morphology and surface of the particles. In this review, we summarise the reported T1 iron oxide nanoparticles and critically revise their properties, synthetic protocols and application, not only in MRI but also in multimodal imaging. In addition, we briefly summarise the most important nanoparticulate Gd and Mn agents to evaluate whether T1 iron oxide nanoparticles can reach Gd/Mn contrast capabilities.

[T1-weighted magnetic resonance imaging contrast agents and their theranostic nanoprobes]

Magnetic resonance imaging (MRI) is an important imaging modality for clinical disease diagnosis, and nearly 50% of clinical MRI examinations require contrast agents to enhance the diagnostic sensitivity. This review provides a summary of the major MRI contrast agents and their classification, and the advantages and limits of the commercially available MRI contrast agents, and elaborates on the exceedingly small magnetic iron oxide nanoparticles (ES-MIONs), dotted core-shell iron and gadolinium hybrid nanoparticles (FeGd-HN) and exceedingly small gadolinium oxide nanoparticles (ES-GON). These nanoparticles can greatly improve the efficiency of T₁-weighted MRI due to their high r₁ value and low r₂/r₁ ratio, and are expected to be translated into clinical contrast agents for T₁-weighted MRI. The authors also review the diagnostic and therapeutic integration system that combines MRI contrast agents with various tumor therapies, such as MRI-guided ferroptosis therapy, radiosensitization therapy, and photothermal therapy, which allow efficient treatment as well as real-time monitoring of tumors and serve as potential cancer therapy strategies. The possible future research directions in the field of MRI-based multifunctional diagnostic and therapeutic formulations are also discussed.

The Transition from Metal-Based to Metal-Free Contrast Agents for T1 Magnetic Resonance Imaging Enhancement

Magnetic resonance imaging (MRI) has received significant attention as the noninvasive diagnostic technique for complex diseases. Image-guided therapeutic strategy for diseases such as cancer has also been at the front line of biomedical research, thanks to the innovative MRI, enhanced by the prior delivery of contrast agents (CAs) into patients' bodies through injection. These CAs have contributed a great deal to the clinical utility of MRI but have been based on metal-containing compounds such as gadolinium, manganese, and iron oxide. Some of these CAs have led to cytotoxicities such as the incurable Nephrogenic Systemic Fibrosis (NSF), resulting in their removal from the market. On the other hand, CAs based on organic nitroxide radicals, by virtue of their structural composition, are metal free and without the aforementioned drawbacks. They also have improved biocompatibility, ease of functionalization, and long blood circulation times, and have been proven to offer tissue contrast enhancement with longitudinal relaxivities comparable with those for the metal-containing CAs. Thus, this Review highlights the recent progress in metal-based CAs and their shortcomings. In addition, the remarkable goals achieved by the organic nitroxide radical CAs in the enhancement of MR images have also been discussed extensively. The focal point of this Review is to emphasize or demonstrate the crucial need for transition into the use of organic nitroxide radicals-metal-free CAs-as against the metal-containing CAs, with the aim of achieving safer application of MRI for early disease diagnosis and image-guided therapy.

Biocompatible iron(II)-doped carbon dots as T1-weighted magnetic resonance contrast agents and fluorescence imaging probes

The one-pot synthesis of iron-doped carbon quantum dots (Fe-CQDs) for use as both magnetic resonance (MR) and fluorescent (dual-mode) imaging nanoprobes is described. Comprehensive characterizations of the material confirmed the successful doping of the CQDs with Fe(II) ions. The imaging probe has a longitudinal relaxivity of 3.92 mM^-1∙s^-1 and a low r₂/r₁ ratio of 1.27, both of which are critical for T₁-weighted contrast agents. The maximum emission of Fe-CQDs locates at 450 nm under 375 nm excitation, which also can be applied to fluorescence imaging. Biotoxicity assessment showed good biocompatibility of the Fe-CQDs. The in-vitro experiments with A549 cells indicated that the Fe-CQDs are viable candidates as dual-mode (MR/fluorescence) imaging nanoprobes. For in-vivo experiments, they exhibit high contrast efficiency, thereby improving the positive contrast in T₁-weighted MR images. In-vivo time-dependent MRI of major organs showed that the Fe-CQDs undergo fast glomerular filtration and can evade immuno-absorption due to their ultra-small size and excellent biocompatibility. Graphical abstract Schematic presentation of the synthesis of Fe-CQDs and applications to magnetic resonance and fluorescent dual-mode imaging.

A New Potential Contrast Agent for Magnetic Resonance Imaging: Iron Oxide-4A Nanocomposite

BACKGROUND

Magnetic resonance imaging (MRI) contrast agents have an important role to differentiate healthy and diseased tissues. Access and design new contrast agents for the optimal use of MRI are necessary. This study aims to evaluate iron oxide-4A nanocomposite ability to act as a magnetic resonance imaging contrast agent.

MATERIAL AND METHODS

Iron oxide-4A nanocomposite (F4A) was synthesized. MTT assay was used to consider the nanocomposite safety for cell culture. The T1 and T2 relaxation times were measured using a 1.5 Tesla clinical MRI scanner. Then the corresponding relaxivities were determined.

RESULTS

The average particle diameter of the nanocomposite was 50 to 100 nm based on scanning electron microscope (SEM) image. A linear relationship between relaxation rates and the Fe concentration of the nanocomposite was obtained. The T1 and T2 relaxivities of the nanocomposite were calculated 5.413 and 1092.1 mM-1.s-1, respectively which led to the T2/T1 relaxivity ratio of 201.75.

CONCLUSION

The high T2/T1 relaxivity ratio of the iron oxide-4A nanocomposite confirms it's potential to act as a T2 contrast agent.

T₁-Weight Magnetic Resonance Imaging Performances of Iron Oxide Nanoparticles Modified with a Natural Protein Macromolecule and an Artificial Macromolecule

To optimize the iron oxide nanoparticles as T₁-weight contrast for in vivo magnetic resonance imaging (MRI), numbers of macromolecule ligands have been explored with considerable effort. However, reports refer to the comparison of the T₁-weight contrast performances of iron oxide nanoparticles modified with natural and artificial macromolecule ligands are still limited. In this work, we used a typical natural protein macromolecule (bovine serum albumin, BSA) and an artificial macromolecule (poly(acrylic acid)-poly(methacrylic acid), PMAA-PTTM) as surface ligands to fabricate Fe₃O₄-BSA and Fe₃O₄-PMAA-PTTM nanoparticles with similar size and magnetization by the coprecipitation method and compared their MRI performances. In vitro and in vivo experiments revealed that Fe₃O₄-BSA with lower cytotoxicity exhibited higher r₂/r₁ ratio in solution and darkening contrast enhancement for liver and kidney sites of mice under T₁-weight imaging, while Fe₃O₄-PMAA-PTTM displayed much lower r₂/r₁ ratio in solution and brighter contrast enhancement for liver and kidney sites. These remarkably different MRI behaviors demonstrated that the surface ligands play an important role for optimizing the MRI performance of Fe₃O₄ nanoparticles. We expect these results may facilitate the design of macromolecule ligands for developing an iron oxide⁻based T₁-weight contrast agent.

Multifunctional Theranostic Nanoparticles Based on Exceedingly Small Magnetic Iron Oxide Nanoparticles for T1-Weighted Magnetic Resonance Imaging and Chemotherapy

The recently emerged exceedingly small magnetic iron oxide nanoparticles (ES-MIONs) (<5 nm) are promising T₁-weighted contrast agents for magnetic resonance imaging (MRI) due to their good biocompatibility compared with Gd-chelates. However, the best particle size of ES-MIONs for T₁ imaging is still unknown because the synthesis of ES-MIONs with precise size control to clarify the relationship between the r₁ (or r₂/r₁) and the particle size remains a challenge. In this study, we synthesized ES-MIONs with seven different sizes below 5 nm and found that 3.6 nm is the best particle size for ES-MIONs to be utilized as T₁-weighted MR contrast agent. To enhance tumor targetability of theranostic nanoparticles and reduce the nonspecific uptake of nanoparticles by normal healthy cells, we constructed a drug delivery system based on the 3.6 nm ES-MIONs for T₁-weighted tumor imaging and chemotherapy. The laser scanning confocal microscopy (LSCM) and flow cytometry analysis results demonstrate that our strategy of precise targeting via exposure or hiding of the targeting ligand RGD₂ on demand is feasible. The MR imaging and chemotherapy results on the cancer cells and tumor-bearing mice reinforce that our DOX@ES-MION3@RGD₂@mPEG3 nanoparticles are promising for high-resolution T₁-weighted MR imaging and precise chemotherapy of tumors.

Family of Bioactive Heparin-Coated Iron Oxide Nanoparticles with Positive Contrast in Magnetic Resonance Imaging for Specific Biomedical Applications

Unfractionated heparin (UFH) and low-molecular-weight heparins (LMWH) are well-known for their anticoagulant properties. There is also currently a growing interest in using LMWH in targeted cancer therapy. In particular, several types inhibit heparanase, a key enzyme overexpressed in the tumor microenvironment that promotes angiogenesis progression and metastasis spreading. Here, we propose iron oxide nanoparticles (HEP-IONP) coated with different heparins of distinct anticoagulant/anti-heparanase activity ratios and suitable for positive contrast in magnetic resonance imaging. As a proof of concept, magnetic resonance angiography (MRA) was conducted in mice up to 3 h after intravenous administration. This new IONP-based positive contrast appropriate for clinic together with the long vascular circulating times can enable innovative theranostic applications if combined with the various bioactivities of the heparins. Indeed, we showed, using advanced in vitro tests, how HEP-IONP anticoagulant or anti-heparanase activities were maintained depending on the heparin species used for the coating. Overall, the study allowed presenting an IONP coated with a commercial LMWH (Lovenox) suggested as a theranostic translational probe for MRA diagnostic and treatment of thrombosis, and an antitumor IONP coated with a specific depolymerized heparin to be used in targeted therapy and diagnostic modalities.

Synthesis, characterization, and evaluation of PEGylated first-row transition metal ferrite nanoparticles as T2contrast agents for high-field MRI

PEGylated MFe₂O₄(M = Mn through Zn) spinel ferrite preparedviaa novel one-pot synthesis were evaluated for high-field (B₀= 9.4 T) magnetic resonance imaging.

Iron Oxide Nanoparticle Based Contrast Agents for Magnetic Resonance Imaging

Magnetic iron oxide nanoparticles (MIONs) have attracted enormous attention due to their wide applications, including for magnetic separation, for magnetic hyperthermia, and as contrast agents for magnetic resonance imaging (MRI). This review article introduces the methods of synthesizing MIONs, and their application as MRI contrast agents. Currently, many methods have been reported for the synthesis of MIONs. Herein, we only focus on the liquid-based synthesis methods including aqueous phase methods and organic phase methods. In addition, the MIONs larger than 10 nm can be used as negative contrast agents and the recently emerged extremely small MIONs (ES-MIONs) smaller than 5 nm are potential positive contrast agents. In this review, we focus on the ES-MIONs because ES-MIONs avoid the disadvantages of MION-based T₂- and gadolinium chelate-based T₁-weighted contrast agents.

Europium-engineered iron oxide nanocubes with high T1 and T2 contrast abilities for MRI in living subjects

Magnetic resonance imaging (MRI) contrast agents with both positive (T1) and negative (T2) contrast abilities are needed in clinical diagnosis for fault-free accurate detection of lesions. We report a facile synthesis of europium-engineered iron oxide (EuIO) nanocubes as T1 and T2 contrast agents for MRI in living subjects. The Eu(iii) oxide-embedded iron oxide nanoparticles significantly increase the T1 relaxivity with an enhanced positive contrast effect. EuIO nanocubes with 14 nm in diameter showed a high r1 value of 36.8 mM(-1) s(-1) with respect to total metal ions (Fe + Eu), which is about 3 times higher than that of Fe3O4 nanoparticles with similar size. Moreover, both r1 and r2 values of EuIO nanocubes can be tuned by varying their sizes and Eu doping ratios. After citrate coating, EuIO nanocubes can provide enhanced T1 and T2 contrast effects in small animals, particularly in the cardiac and liver regions. This work may provide an insightful strategy to design MRI contrast agents with both positive and negative contrast abilities for biomedical applications.

One-step synthesis of degradable T(1)-FeOOH functionalized hollow mesoporous silica nanocomposites from mesoporous silica spheres

The combination of a hollow mesoporous structure and a magnetic resonance (MR) contrast agent has shown its potential in simultaneous drug delivery and cell tracking applications. However, the preparation of this kind of nanocomposite is complicated and usually takes several days, which is unsuitable for scaled-up production. To overcome these hurdles, we report herein a facile method to synthesize iron oxide hydroxide functionalized hollow mesoporous silica spheres (FeOOH/HMSS) in a one-step manner. By carefully controlling the reaction kinetics of K2FeO4 in water, the gram-scale production of FeOOH/HMSS can be readily achieved at 60 °C for as short as 30 min. Most importantly, this synthetic process is also cost-effective and eco-friendly in both the precursor (K2FeO4 and H2O) and the product (FeOOH). The mechanism for the formation of a hollow structure was carefully investigated, which involves the synergetic effect of the surfactant CTAB and the side product KOH. Having outstanding biocompatibility, these degradable nanocolloids also demonstrate their feasibility in in vitro/vivo MR imaging and in vitro drug delivery.