Design of Safe Nanotherapeutics for the Excretion of Excess Systemic Toxic Iron

Hub genes, a diagnostic model, and immune infiltration based on ferroptosis-linked genes in schizophrenia

Background

Schizophrenia (SCZ) is a prevalent and serious mental disorder, and the exact pathophysiology of this condition is not fully understood. In previous studies, it has been proven that ferroprotein levels are high in SCZ. It has also been shown that this inflammatory response may modify fibromodulin. Accumulating evidence indicates a strong link between metabolism and ferroptosis. Therefore, the present study aims to identify ferroptosis-linked hub genes to further investigate the role that ferroptosis plays in the development of SCZ.

Material and methods

From the GEO database, four microarray data sets on SCZ (GSE53987, GSE38481, GSE18312, and GSE38484) and ferroptosis-linked genes were extracted. Using the prefrontal cortex expression matrix of SCZ patients and healthy individuals as the control group from GSE53987, weighted gene co-expression network analysis (WGCNA) was performed to discover SCZ-linked module genes. From the feed, genes associated with ferroptosis were retrieved. The intersection of the module and ferroptosis-linked genes was done to obtain the hub genes. Then, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, and Gene Set Enrichment Analysis (GSEA) were conducted. The SCZ diagnostic model was established using logistic regression, and the GSE38481, GSE18312, and GSE38484 data sets were used to validate the model. Finally, hub genes linked to immune infiltration were examined.

Results

A total of 13 SCZ module genes and 7 hub genes linked to ferroptosis were obtained: DECR1, GJA1, EFN2L2, PSAT1, SLC7A11, SOX2, and YAP1. The GO/KEGG/GSEA study indicated that these hub genes were predominantly enriched in mitochondria and lipid metabolism, oxidative stress, immunological inflammation, ferroptosis, Hippo signaling pathway, AMP-activated protein kinase pathway, and other associated biological processes. The diagnostic model created using these hub genes was further confirmed using the data sets of three blood samples from patients with SCZ. The immune infiltration data showed that immune cell dysfunction enhanced ferroptosis and triggered SCZ.

Conclusion

In this study, seven critical genes that are strongly associated with ferroptosis in patients with SCZ were discovered, a valid clinical diagnostic model was built, and a novel therapeutic target for the treatment of SCZ was identified by the investigation of immune infiltration.

Beneficial effects of the combination of BCc1 and Hep-S nanochelating-based medicines on IL-6 in hospitalized moderate COVID-19 adult patients: a randomized, double-blind, placebo-controlled clinical trial

BACKGROUND

In the severe forms of COVID-19 and many other infectious diseases, the patients develop a cytokine storm syndrome (CSS) where pro-inflammatory cytokines such as IL-6 and TNF-α play a key role in the development of this serious process. Selenium and iron are two important trace minerals, and their metabolism is tightly connected to immune system function. Numerous studies highlight the role of selenium and iron metabolism changes in the procedure of COVID-19 inflammation. The immunomodulator effect of nanomedicines that are synthesized based on nanochelating technology has been proved in previous studies. In the present study, the effects of the combination of BCc1(with iron-chelating property) and Hep-S (containing selenium) nanomedicines on mentioned cytokines levels in hospitalized moderate COVID-19 patients were evaluated.

METHODS

Laboratory-confirmed moderate COVID-19 patients were enrolled to participate in a randomized, double-blind, placebo-controlled study in two separate groups: combination of BCc1 and Hep-S (N = 62) (treatment) or placebo (N = 60) (placebo). The blood samples were taken before medications on day zero, at discharge, and 28 days after consumption to measure hematological and biochemical parameters and cytokine levels. The clinical symptoms of all the patients were recorded according to an assessment questionnaire before the start of the treatment and on days 3 and discharge day.

RESULTS

The results revealed that consumption of the nanomedicines led to a significant decrease in the mean level of IL-6 cytokine, and at the end of the study, there was a 77% downward trend in IL-6 in the nanomedicine group, while an 18% increase in the placebo group (p < 0.05). In addition, the patients in the nanomedicines group had lower TNF-α levels; accordingly, there was a 21% decrease in TNF-α level in the treatment group, while a 31% increase in this cytokine level in the placebo was observed (p > 0.05). On the other hand, in nanomedicines treated groups, clinical scores of coughing, fatigue, and need for oxygen therapy improved.

CONCLUSIONS

In conclusion, the combination of BCc1 and Hep-S inhibits IL-6 as a highly important and well-known cytokine in COVID-19 pathophysiology and presents a promising view for immunomodulation that can manage CSS.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials RCT20170731035423N2 . Registered on June 12, 2020.

Polymer Nanoantidotes

Intoxication is one of the most common causes of accidental death globally. Although some antidotes capable of neutralizing the toxicity of certain xenobiotics have become well established, the current reality is that clinicians primarily rely on nonspecific extracorporeal techniques to remove toxins. Nano-intervention strategies in which nanoantidotes neutralize toxicity in situ via physical interaction, chemical bonding, or biomimetic clearance have begun to show clinical potential. However, most nanoantidotes remain in the proof-of-concept stage, and the difficulty of constructing clinical relevance models and the unclear pharmacokinetics of nanoantidotes hinder their translation to clinic. This Concept reviews the detoxification mechanisms of polymer nanoantidotes and predicts the opportunities and challenges associated with their clinical application.

Natural polyphenol-based nanoparticles for the treatment of iron-overload disease

Iron-overload diseases are characterized by a variety of symptoms resulting from excessive iron stores, oxidative stress and consequent end-organ damage. Deferoxamine (DFO) is an iron-chelator that can protect tissues from iron-induced damage. However, its application is limited due to its low stability and weak free radical scavenging ability. Herein, natural polyphenols have been employed to enhance the protective efficacy of DFO through the construction of supramolecular dynamic amphiphiles, which self-assemble into spherical nanoparticles with excellent scavenging capacity against both iron (III) and reactive oxygen species (ROS). This class of natural polyphenols-assisted nanoparticles was found to exhibit enhanced protective efficacy both in vitro in an iron-overload cell model and in vivo in an intracerebral hemorrhage model. This strategy of constructing natural polyphenols- assisted nanoparticles could benefit the treatment of iron-overload related diseases with excessive accumulation of toxic or harmful substances.

Current insights into the functional roles of ferroptosis in musculoskeletal diseases and therapeutic implications

Ferroptosis is a novel type of cell death associated with iron accumulation and excessive lipid peroxidation. Elucidating the underlying molecular mechanisms of ferroptosis is intensively related to the development and treatment of multiple diseases, including musculoskeletal disorders. Moreover, in vitro and in vivo studies have shown the importance of oxidative stress in musculoskeletal conditions such as osteoporosis, osteoarthritis, rheumatoid arthritis, and osteosarcoma. Ferroptosis-derived clinical management of musculoskeletal diseases offers tremendous and attractive opportunities. Notably, ferroptosis agonists have been proven to enhance the sensitivity of osteosarcoma cells to conventional therapeutic strategies. In this review, we have mainly focused on the implications of ferroptosis regulation in the pathophysiology and therapeutic response of musculoskeletal disorders. Understanding roles of ferroptosis for controlling musculoskeletal diseases might provide directions for ferroptosis-driven therapies, which could be promising for the development of novel therapeutic strategies.

A Dual-Kinetic Control Strategy for Designing Nano-Metamaterials: Novel Class of Metamaterials with Both Characteristic and Whole Sizes of Nanoscale

Increasingly intricate in their multilevel multiscale microarchitecture, metamaterials with unique physical properties are challenging the inherent constraints of natural materials. Their applicability in the nanomedicine field still suffers because nanomedicine requires a maximum size of tens to hundreds of nanometers; however, this size scale has not been achieved in metamaterials. Therefore, "nano-metamaterials," a novel class of metamaterials, are introduced, which are rationally designed materials with multilevel microarchitectures and both characteristic sizes and whole sizes at the nanoscale, investing in themselves remarkably unique and significantly enhanced material properties as compared with conventional nanomaterials. Microarchitectural regulation through conventional thermodynamic strategy is limited since the thermodynamic process relies on the frequency-dependent effective temperature, T_eff (ω), which limits the architectural regulation freedom degree. Here, a novel dual-kinetic control strategy is designed to fabricate nano-metamaterials by freezing a high-free energy state in a T_eff (ω)-constant system, where two independent dynamic processes, non-solvent induced block copolymer (BCP) self-assembly and osmotically driven self-emulsification, are regulated simultaneously. Fe³⁺ -"onion-like core@porous corona" (Fe³⁺ -OCPCs) nanoparticles (the products) have not only architectural complexity, porous corona and an onion-like core but also compositional complexity, Fe³⁺ chelating BCP assemblies. Furthermore, by using Fe³⁺ -OCPCs as a model material, a microstructure-biological performance relationship is manifested in nano-metamaterials.

Iron metabolism in colorectal cancer

Iron, as one of the essential trace elements in the human body, is involved in a wide range of critical biochemical reactions and physiological processes, including the maintenance of the normal cell cycle, mitochondrial function, nucleotide metabolism, and immune response. In this context, iron is naturally associated with cancer occurrence. Cellular iron deficiency can induce apoptosis, however, iron can also engage in potentially harmful reactions that produce free radicals because of its capacity to gain and lose electrons. Studies suggest that dietary iron, particularly heme iron, may be one of the leading causes of colorectal cancer (CRC). Moreover, patients with CRC have abnormal iron absorption, storage, utilization, and exportation. Therefore, iron is crucial for the development and progression of CRC. Elaborating on the alterations in iron metabolism during the onset and advancement of CRC would help to further explain the role and mechanism of iron inside the body. Thus, we reviewed the alterations in numerous iron metabolism-related molecules and their roles in CRC, which may provide new clues between iron metabolism and CRC.

Synergetic delivery of artesunate and isosorbide 5-mononitrate with reduction-sensitive polymer nanoparticles for ovarian cancer chemotherapy

Ovarian cancer is a highly fatal gynecologic malignancy worldwide. Chemotherapy remains the primary modality both for primary and maintenance treatments of ovarian cancer. However, the progress in developing chemotherapeutic agents for ovarian cancer has been slow in the past 20 years. Thus, new and effective chemotherapeutic drugs are urgently needed for ovarian cancer treatment. A reduction-responsive synergetic delivery strategy (PSSP@ART-ISMN) with co-delivery of artesunate and isosorbide 5-mononitrate was investigated in this research study. PSSP@ART-ISMN had various effects on tumor cells, such as (i) inducing the production of reactive oxygen species (ROS), which contributes to mitochondrial damage; (ii) providing nitric oxide and ROS for the tumor cells, which further react to generate highly toxic reactive nitrogen species (RNS) and cause DNA damage; and (iii) arresting cell cycle at the G0/G1 phase and inducing apoptosis. PSSP@ART-ISMN also demonstrated excellent antitumor activity with good biocompatibility in vivo. Taken together, the results of this work provide a potential delivery strategy for chemotherapy in ovarian cancer.

Active transport nanochelators for the reduction of liver iron burden in iron overload

Liver dysfunction and failure account for a major portion of premature deaths in patients suffering from various iron associated pathogeneses, particularly primary and secondary iron overload disorders, despite intensive treatment. The liver is a central player in iron homeostasis and a major iron storage organ, and currently, there are no active approaches for the excretion of excess liver iron. Herein, we report a new method for the rapid reduction of iron burden in iron overload diseases by developing a new class of liver targeted nanochelators with favorable pharmacokinetics and biodistribution. The new nanochelators bypass the reticuloendothelial system and specifically target hepatocytes without non-specific accumulation in other organs. The targeted nanochelators bound and neutralized excess iron in the liver and from the vasculature and, eventually leading to rapid hepatobiliary excretion of labile iron. Further, these rapidly excreted nanochelators did not induce toxicity in the liver, were highly cytocompatible in both iron overload and non-loaded conditions, and were promising in mitigating iron triggered free radical oxidative damage. These studies provide key insights into the development of organ targeted nanochelating systems and the rapid reduction of iron burden in vivo. This methodology allows for further development of nanotherapeutics for specific iron overload diseases.

Injectable Thermosensitive Hydrogels for a Sustained Release of Iron Nanochelators

Deferoxamine (DFO) is an FDA-approved iron-chelating agent which shows good therapeutic efficacy, however, its short blood half-life presents challenges such as the need for repeated injections or continuous infusions. Considering the lifelong need of chelating agents for iron overload patients, a sustained-release formulation that can reduce the number of chelator administrations is essential. Here, injectable hydrogel formulations prepared by integrating crosslinked hyaluronic acid into Pluronic F127 for an extended release of DFO nanochelators are reported. The subcutaneously injected hydrogel shows a thermosensitive sol-gel transition at physiological body temperature and provides a prolonged release of renal clearable nanochelators over 2 weeks, resulting in a half-life 47-fold longer than that of the nanochelator alone. In addition, no chronic toxicity of the nanochelator-loaded hydrogel is confirmed by biochemical and histological analyses. This injectable hydrogel formulation with DFO nanochelators has the potential to be a promising formulation for the treatment of iron overload disorders.

Repurposing ICG enables MR/PA imaging signal amplification and iron depletion for iron-overload disorders

Precise and noninvasive theranostic methods to quantify and deplete focal iron are of crucial importance for iron-overload disorders. Here, we developed an indocyanine green (ICG)–based imaging platform to reveal Fe³⁺ in vitro and in vivo. The high sensitivity and specificity of ICG-Fe interaction facilitated MR images with a marked correlation between T₁ signal intensity ratio (T₁SIR) changes and Fe³⁺ concentration in rodent models and humans. On the basis of these findings, a rational design for coordination-driven self-assembly ICG-Lecithin (ICG/Leci) was proposed to determine Fe³⁺. The enhancement of photoacoustic signal at 890 nm with increasing Fe³⁺ concentration showed an over 600% higher linear slope than that of T₁SIR changes in animal models. ICG/Leci also promoted a 100% increase in iron depletion in the liver compared with deferoxamine. The high MR sensitivity and superior photoacoustic contrast, combined with enhanced iron depletion, demonstrate that ICG/Leci is a promising theranostic agent for simultaneous detection and treatment of iron-overload disorders.

Chelators for Treatment of Iron and Copper Overload: Shift from Low-Molecular-Weight Compounds to Polymers

Iron and copper are essential micronutrients needed for the proper function of every cell. However, in excessive amounts, these elements are toxic, as they may cause oxidative stress, resulting in damage to the liver and other organs. This may happen due to poisoning, as a side effect of thalassemia infusion therapy or due to hereditary diseases hemochromatosis or Wilson's disease. The current golden standard of therapy of iron and copper overload is the use of low-molecular-weight chelators of these elements. However, these agents suffer from severe side effects, are often expensive and possess unfavorable pharmacokinetics, thus limiting the usability of such therapy. The emerging concepts are polymer-supported iron- and copper-chelating therapeutics, either for parenteral or oral use, which shows vivid potential to keep the therapeutic efficacy of low-molecular-weight agents, while avoiding their drawbacks, especially their side effects. Critical evaluation of this new perspective polymer approach is the purpose of this review article.

Role of Iron in the Molecular Pathogenesis of Diseases and Therapeutic Opportunities

Iron is an essential mineral that serves as a prosthetic group for a variety of proteins involved in vital cellular processes. The iron economy within humans is highly conserved in that there is no proper iron excretion pathway. Therefore, iron homeostasis is highly evolved to coordinate iron acquisition, storage, transport, and recycling efficiently. A disturbance in this state can result in excess iron burden in which an ensuing iron-mediated generation of reactive oxygen species imparts widespread oxidative damage to proteins, lipids, and DNA. On the contrary, problems in iron deficiency either due to genetic or nutritional causes can lead to a number of iron deficiency disorders. Iron chelation strategies have been in the works since the early 1900s, and they still remain the most viable therapeutic approach to mitigate the toxic side effects of excess iron. Intense investigations on improving the efficacy of chelation strategies while being well tolerated and accepted by patients have been a particular focus for many researchers over the past 30 years. Moreover, recent advances in our understanding on the role of iron in the pathogenesis of different diseases (both in iron overload and iron deficiency conditions) motivate the need to develop new therapeutics. We summarized recent investigations into the role of iron in health and disease conditions, iron chelation, and iron delivery strategies. Information regarding small molecule as well as macromolecular approaches and how they are employed within different disease pathogenesis such as primary and secondary iron overload diseases, cancer, diabetes, neurodegenerative diseases, infections, and in iron deficiency is provided.

Advances in Sickle Cell Disease Treatments

Sickle Cell Disease (SCD) is an inherited disorder of red blood cells that is caused by a single mutation in the β -globin gene. The disease, which afflicts millions of patients worldwide mainly in low income countries, is characterized by high morbidity, mortality and low life expectancy. The new pharmacological and non-pharmacological strategies for SCD is urgent in order to promote treatments able to reduce patient's suffering and improve their quality of life. Since the FDA approval of HU in 1998, there have been few advances in discovering new drugs; however, in the last three years voxelotor, crizanlizumab, and glutamine have been approved as new therapeutic alternatives. In addition, new promising compounds have been described to treat the main SCD symptoms. Herein, focusing on drug discovery, we discuss new strategies to treat SCD that have been carried out in the last ten years to discover new, safe, and effective treatments. Moreover, non-pharmacological approaches, including red blood cell exchange, gene therapy and hematopoietic stem cell transplantation will be presented.

Efficient Iron and ROS Nanoscavengers for Brain Protection after Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) will be accompanied by the overload of iron and reactive oxygen species (ROS) following hematoma clearance. Although deferoxamine (DFO) has been widely utilized as a clinical first-line siderophore to remove the iron overload, the ROS-inducing damage still greatly limits the therapeutic effect of DFO. To address this issue, we designed and fabricated a series of dual-functional macromolecular nanoscavengers featuring high-density DFO units and catechol moieties. Note that the former units could effectively remove the iron overload, while the latter ones could efficiently deplete the ROS. The resulting nanoscavengers efficiently down-regulate the iron and ROS levels as well as significantly reduce the cell death in both iron-overloaded RAW 264.7 cells and the ICH mice model. This work suggests a novel clue for the ICH-ameliorated iron-depleting interventional therapeutic regimen.

Reactive Oxygen Species-Triggered Dissociation of a Polyrotaxane-Based Nanochelator for Enhanced Clearance of Systemic and Hepatic Iron

Chronic blood transfusions are used to alleviate anemic symptoms in thalassemia and sickle cell anemia patients but can eventually result in iron overload (IO) and subsequently lead to severe oxidative stress in cells and tissues. Deferoxamine (DFO) is clinically approved to treat transfusional IO, but the use of the iron chelator is hindered by nonspecific toxicity and poor pharmacokinetic (PK) properties in humans, resulting in the need to administer the drug via long-term infusion regimens that can often lead to poor patient compliance. Herein, a nanochelator system that uses the characteristic IO physiological environment to dissociate was prepared through the incorporation of DFO and reactive oxygen species (ROS)-sensitive thioketal groups into an α-cyclodextrin-based polyrotaxane platform (rPR-DFO). ROS-induced dissociation of this nanochelator (ca. 10 nm) into constructs averaging 2 nm in diameter significantly increased urine and fecal elimination of excess iron in vivo. In addition to significantly improved PK properties, rPR-DFO was well-tolerated in mice and no adverse side effects were noted in single high dose or multiple dose acute toxicity studies. The overall features of rPR-DFO as a promising system for iron chelation therapy can be attributed to a combination of the nanochelator's improved PK, favorable distribution to the liver, and ROS-induced dissociation properties into constructs <6 nm for faster renal elimination. This ROS-responsive nanochelator design may serve as a promising alternative for safely prolonging the circulation of DFO and more rapidly eliminating iron chelates from the body in iron chelation therapy regimens requiring repeated dosing of nanochelators.

Polyglycerol-Based Macromolecular Iron Chelator Adjuvants for Antibiotics To Treat Drug-Resistant Bacteria

Iron is an essential micronutrient for life. Its redox activity is a key component in a plethora of vital enzymatic reactions that take place in processes such as drug metabolism, DNA synthesis, steroid synthesis, gene regulation, and cellular respiration (oxygen transport and the electron transport chain). Bacteria are highly dependent on iron for their survival and growth and have specific mechanisms to acquire iron. Limiting the availability of iron to bacteria, thereby preventing their growth, provides new opportunities to treat infection in the era of the persistent rise of antibiotic-resistant bacteria. In this work, we have developed macromolecular iron chelators, conjugates of a high-affinity iron chelator (HBEDS) with polyglycerol, in an attempt to sequester iron uptake by bacteria to limit their growth in order to enhance antibiotic activity. The new macromolecular chelators are successful in slowing the growth of Staphylococcus aureus and worked as an efficient bacteriostatic against S. aureus. Further, these cytocompatible macrochelators acted as effective adjuvants to prevent bacterial growth when used in conjunction with antibiotics. The adjuvant activity of the macrochelators depends on their molecular weight and the chelator density on these molecules. These selective macro iron(III) chelators are highly efficient in growth inhibition and killing of methicillin-resistant S. aureus in conjunction with a low concentration of rifampicin.

Towards Robust Delivery of Antimicrobial Peptides to Combat Bacterial Resistance

Antimicrobial peptides (AMPs), otherwise known as host defence peptides (HDPs), are naturally occurring biomolecules expressed by a large array of species across the phylogenetic kingdoms. They have great potential to combat microbial infections by directly killing or inhibiting bacterial activity and/or by modulating the immune response of the host. Due to their multimodal properties, broad spectrum activity, and minimal resistance generation, these peptides have emerged as a promising response to the rapidly concerning problem of multidrug resistance (MDR). However, their therapeutic efficacy is limited by a number of factors, including rapid degradation, systemic toxicity, and low bioavailability. As such, many strategies have been developed to mitigate these limitations, such as peptide modification and delivery vehicle conjugation/encapsulation. Oftentimes, however, particularly in the case of the latter, this can hinder the activity of the parent AMP. Here, we review current delivery strategies used for AMP formulation, focusing on methodologies utilized for targeted infection site release of AMPs. This specificity unites the improved biocompatibility of the delivery vehicle with the unhindered activity of the free AMP, providing a promising means to effectively translate AMP therapy into clinical practice.

Hydroxamic Acid: An Underrated Moiety? Marrying Bioinorganic Chemistry and Polymer Science

Even 150 years after their discovery, hydroxamic acids are mainly known as the starting material for the Lossen rearrangement in textbooks. However, hydroxamic acids feature a plethora of existing and potential applications ranging from medical purposes to materials science, based on their excellent complexation properties. This underrated functional moiety can undergo a broad variety of organic transformations and possesses unique coordination properties for a large variety of metal ions, for example, Fe(III), Zn(II), Mn(II), and Cr(III). This renders it ideal for biomedical applications in the field of metal-associated diseases or the inhibition of metalloenzymes, as well as for the separation of metals. Considering their chemical stability and reactivity, their biological origin and both medical and industrial applications, this Perspective aims at highlighting hydroxamic acids as highly promising chelators in the fields of both medical and materials science. Furthermore, the state of the art in combining hydroxamic acids with a variety of polymer structures is discussed and a perspective regarding their vast potential at the interface of bioinorganic and polymer chemistry is given.

Blood circulation of soft nanomaterials is governed by dynamic remodeling of protein opsonins at nano-biointerface

Nanomaterials in the blood must mitigate the immune response to have a prolonged vascular residency in vivo. The composition of the protein corona that forms at the nano-biointerface may be directing this, however, the possible correlation of corona composition with blood residency is currently unknown. Here‚ we report a panel of new soft single molecule polymer nanomaterials (SMPNs) with varying circulation times in mice (t_1/2β ~ 22 to 65 h) and use proteomics to probe protein corona at the nano-biointerface to elucidate the mechanism of blood residency of nanomaterials. The composition of the protein opsonins on SMPNs is qualitatively and quantitatively dynamic with time in circulation. SMPNs that circulate longer are able to clear some of the initial surface-bound common opsonins, including immunoglobulins, complement, and coagulation proteins. This continuous remodelling of protein opsonins may be an important decisive step in directing elimination or residence of soft nanomaterials in vivo.

The blood circulation time is important to the biomedical application of nanomaterials. Here, the authors explore the effect of protein corona formation on the blood residency of nanomaterials and show circulation times are governed by the dynamic remodelling of protein opsonins in vivo.

Combating iron overload: a case for deferoxamine-based nanochelators

While iron is a nutrient metal, iron overload can result in multiple organ failures. Iron chelators, such as deferoxamine, are commonly used to ameliorate iron overload conditions. However, their uses are limited due to poor pharmacokinetics and adverse effects. Many novel chelator formulations have been developed to overcome these drawbacks. In this review, we have discussed various nanochelators, including linear and branched polymers, dendrimers, polyrotaxane, micelles, nanogels, polymeric nanoparticles and liposomes. Although these research efforts have mainly been focused on nanochelators with longer half-lives, prolonged residence of polymers in the body could raise potential safety issues. We also discussed recent advances in nanochelation technologies, including mechanism-based, long-acting nanochelators.