Magnetodendrimers allow endosomal magnetic labeling and in vivo tracking of stem cells

Last Fifteen Years of Nanotechnology Application with Our Contribute

Currently, nanotechnology is the most promising science, engineering, and technology conducted at the nanoscale (nm), which is used in several sectors. Collectively, nanotechnology is causing a new industrial revolution, and nano-based products are becoming increasingly important for the global market and economy. The interest in nanomaterials has been strongly augmented during the last two decades, and this fact can be easily evaluated by considering the number of studies present in the literature. In November 2024, they accounted for 764,279 experimental studies developed in the years 2009-2024. During such a period, our group contributed to the field of applicative nanotechnology with several experimental and review articles, which we hope could have relevantly enhanced the knowledge of the scientific community. In this new publication, an exhaustive overview regarding the main types of developed nanomaterials, the characterization techniques, and their applications has been discussed. Particular attention has been paid to nanomaterials employed for the enhancement of bioavailability and delivery of bioactive molecules and to those used for ameliorating traditional food packaging. Then, we briefly reviewed our experimental studies on the development of nanoparticles (NPs), dendrimers, micelles, and liposomes for biomedical applications by collecting inherent details in a reader-friendly table. A brief excursus about our reviews on the topic has also been provided, followed by the stinging question of nanotoxicology. Indeed, although the application of nanotechnology translates into a great improvement in the properties of non-nanosized pristine materials, there may still be a not totally predictable risk for humans, animals, and the environment associated with an extensive application of NPs. Nanotoxicology is a science in rapid expansion, but several sneaky risks are not yet fully disclosed. So, the final part of this study discusses the pending issue related to the possible toxic effects of NPs and their impact on customers' acceptance in a scenario of limited knowledge.

Magnetic iron oxide nanogels for combined hyperthermia and drug delivery for cancer treatment

Hyperthermia and chemotherapy represent potential modalities for cancer treatments. However, hyperthermia can be invasive, while chemotherapy drugs often have severe side effects. Recent clinical investigations have underscored the potential synergistic efficacy of combining hyperthermia with chemotherapy, leading to enhanced cancer cell killing. In this context, magnetic iron oxide nanogels have emerged as promising candidates as they can integrate superparamagnetic iron oxide nanoparticles (IONPs), providing the requisite magnetism for magnetic hyperthermia, with the nanogel scaffold facilitating smart drug delivery. This review provides an overview of the synthetic methodologies employed in fabricating magnetic nanogels. Key properties and designs of these nanogels are discussed and challenges for their translation to the clinic and the market are summarised.

Dual Nanoparticle Conjugates for Highly Sensitive and Versatile Sensing Using 19 F Magnetic Resonance Imaging

Fluorine magnetic resonance imaging (19 F MRI) has emerged as an attractive alternative to conventional 1 H MRI due to enhanced specificity deriving from negligible background signal in this modality. We report a dual nanoparticle conjugate (DNC) platform as an aptamer-based sensor for use in 19 F MRI. DNC consists of core-shell nanoparticles with a liquid perfluorocarbon core and a mesoporous silica shell (19 F-MSNs), which give a robust 19 F MR signal, and superparamagnetic iron oxide nanoparticles (SPIONs) as magnetic quenchers. Due to the strong magnetic quenching effects of SPIONs, this platform is uniquely sensitive and functions with a low concentration of SPIONs (4 equivalents) relative to 19 F-MSNs. The probe functions as a "turn-on" sensor using target-induced dissociation of DNA aptamers. The thrombin binding aptamer was incorporated as a proof-of-concept (DNCThr ), and we demonstrate a significant increase in 19 F MR signal intensity when DNCThr is incubated with human α-thrombin. This proof-of-concept probe is highly versatile and can be adapted to sense ATP and kanamycin as well. Importantly, DNCThr generates a robust 19 F MRI "hot-spot" signal in response to thrombin in live mice, establishing this platform as a practical, versatile, and biologically relevant molecular imaging probe.

Synergies in stem cell research: Integrating technologies, strategies, and bionanomaterial innovations

Since the 1960 s, there has been a substantial amount of research directed towards investigating the biology of several types of stem cells, including embryonic stem cells, brain cells, and mesenchymal stem cells. In contemporary times, a wide array of stem cells has been utilized to treat several disorders, including bone marrow transplantation. In recent years, stem cell treatment has developed as a very promising and advanced field of scientific research. The progress of therapeutic methodologies has resulted in significant amounts of anticipation and expectation. Recently, there has been a notable proliferation of experimental methodologies aimed at isolating and developing stem cells, which have emerged concurrently. Stem cells possess significant vitality and exhibit vigorous proliferation, making them suitable candidates for in vitro modification. This article examines the progress made in stem cell isolation and explores several methodologies employed to promote the differentiation of stem cells. This study also explores the method of isolating bio-nanomaterials and discusses their viewpoint in the context of stem cell research. It also covers the potential for investigating stem cell applications in bioprinting and the usage of bionanomaterial in stem cell-related technologies and research. In conclusion, the review article concludes by highlighting the importance of incorporating state-of-the-art methods and technological breakthroughs into the future of stem cell research. Putting such an emphasis on constant innovation highlights the ever-changing character of science and the never-ending drive toward unlocking the maximum therapeutic potential of stem cells. This review would be a useful resource for researchers, clinicians, and policymakers in the stem cell research area, guiding the next steps in this fast-developing scientific concern.

Recent Developments in Metallic Degradable Micromotors for Biomedical and Environmental Remediation Applications

Synthetic micromotor has gained substantial attention in biomedicine and environmental remediation. Metal-based degradable micromotor composed of magnesium (Mg), zinc (Zn), and iron (Fe) have promise due to their nontoxic fuel-free propulsion, favorable biocompatibility, and safe excretion of degradation products Recent advances in degradable metallic micromotor have shown their fast movement in complex biological media, efficient cargo delivery and favorable biocompatibility. A noteworthy number of degradable metal-based micromotors employ bubble propulsion, utilizing water as fuel to generate hydrogen bubbles. This novel feature has projected degradable metallic micromotors for active in vivo drug delivery applications. In addition, understanding the degradation mechanism of these micromotors is also a key parameter for their design and performance. Its propulsion efficiency and life span govern the overall performance of a degradable metallic micromotor. Here we review the design and recent advancements of metallic degradable micromotors. Furthermore, we describe the controlled degradation, efficient in vivo drug delivery, and built-in acid neutralization capabilities of degradable micromotors with versatile biomedical applications. Moreover, we discuss micromotors' efficacy in detecting and destroying environmental pollutants. Finally, we address the limitations and future research directions of degradable metallic micromotors.

Intranasal delivery of stem cells labeled by nanoparticles in neurodegenerative disorders: Challenges and opportunities

Neurodegenerative disorders occur through progressive loss of function or structure of neurons, with loss of sensation and cognition values. The lack of successful therapeutic approaches to solve neurologic disorders causes physical disability and paralysis and has a significant socioeconomic impact on patients. In recent years, nanocarriers and stem cells have attracted tremendous attention as a reliable approach to treating neurodegenerative disorders. In this regard, nanoparticle-based labeling combined with imaging technologies has enabled researchers to survey transplanted stem cells and fully understand their fate by monitoring their survival, migration, and differentiation. For the practical implementation of stem cell therapies in the clinical setting, it is necessary to accurately label and follow stem cells after administration. Several approaches to labeling and tracking stem cells using nanotechnology have been proposed as potential treatment strategies for neurological diseases. Considering the limitations of intravenous or direct stem cell administration, intranasal delivery of nanoparticle-labeled stem cells in neurological disorders is a new method of delivering stem cells to the central nervous system (CNS). This review describes the challenges and limitations of stem cell-based nanotechnology methods for labeling/tracking, intranasal delivery of cells, and cell fate regulation as theragnostic labeling. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease.

Magnetic force-based cell manipulation for in vitro tissue engineering

Cell manipulation techniques such as those based on three-dimensional (3D) bioprinting and microfluidic systems have recently been developed to reconstruct complex 3D tissue structures in vitro. Compared to these technologies, magnetic force-based cell manipulation is a simpler, scaffold- and label-free method that minimally affects cell viability and can rapidly manipulate cells into 3D tissue constructs. As such, there is increasing interest in leveraging this technology for cell assembly in tissue engineering. Cell manipulation using magnetic forces primarily involves two key approaches. The first method, positive magnetophoresis, uses magnetic nanoparticles (MNPs) which are either attached to the cell surface or integrated within the cell. These MNPs enable the deliberate positioning of cells into designated configurations when an external magnetic field is applied. The second method, known as negative magnetophoresis, manipulates diamagnetic entities, such as cells, in a paramagnetic environment using an external magnetic field. Unlike the first method, this technique does not require the use of MNPs for cell manipulation. Instead, it leverages the magnetic field and the motion of paramagnetic agents like paramagnetic salts (Gadobutrol, MnCl2, etc.) to propel cells toward the field minimum, resulting in the assembly of cells into the desired geometrical arrangement. In this Review, we will first describe the major approaches used to assemble cells in vitro-3D bioprinting and microfluidics-based platforms-and then discuss the use of magnetic forces for cell manipulation. Finally, we will highlight recent research in which these magnetic force-based approaches have been applied and outline challenges to mature this technology for in vitro tissue engineering.

Scaffold Using Chitosan, Agarose, Cellulose, Dextran and Protein for Tissue Engineering-A Review

Biological macromolecules like polysaccharides/proteins/glycoproteins have been widely used in the field of tissue engineering due to their ability to mimic the extracellular matrix of tissue. In addition to this, these macromolecules are found to have higher biocompatibility and no/lesser toxicity when compared to synthetic polymers. In recent years, scaffolds made up of proteins, polysaccharides, or glycoproteins have been highly used due to their tensile strength, biodegradability, and flexibility. This review is about the fabrication methods and applications of scaffolds made using various biological macromolecules, including polysaccharides like chitosan, agarose, cellulose, and dextran and proteins like soy proteins, zein proteins, etc. Biopolymer-based nanocomposite production and its application and limitations are also discussed in this review. This review also emphasizes the importance of using natural polymers rather than synthetic ones for developing scaffolds, as natural polymers have unique properties, like high biocompatibility, biodegradability, accessibility, stability, absence of toxicity, and low cost.

Superparamagnetic Iron Oxide-Labeled Leishmania major Can Be Traced in Fibroblasts

Introduction

Leishmaniasis is still a neglected tropical disease that can endanger more than 350 million people among 98 countries. Leishmania can survive in fibroblasts as latent inactive forms. This study was conducted to evaluate the role of superparamagnetic iron oxide nanoparticles (SPIONs) in cell culture for tracking the labeled Leishmania major in fibroblasts.

Methods

Dextran-coated SPIONs were used for labeling L. major in co-culture of fibroblasts with the parasite. To quantify and trace SPION-labeled Leishmania, Prussian blue staining was undertaken. Fibroblast characterization was undertaken by real time polymerase chain reaction. Transmission electron microscope (TEM) was used for confirming the entry of the labeled L. major to the cytoplasm and the nucleus of the fibroblast.

Results

Fibroblasts were spindle-shaped and adherent to culture flasks. Promastigotes were with thin elongated lance-like morphology with an anterior kinetoplast and an emergent free flagellum. Prussian blue staining revealed that internalized SPIONs were localized within cytoplasm and nucleus of the fibroblasts after 24 hours of culture. Prussian blue staining successfully showed the presence of iron (stained blue) in labeled L. major within the fibroblasts. This finding was confirmed by TEM, and labeled L. major was detected in the fibroblast cytoplasm and nucleus too.

Conclusion

We can conclude that SPIONs are safe, inexpensive, easy to use, and accurate, and a fast method to label Leishmania parasite in cells that the parasite can be latent, such as fibroblasts. These findings can open a new window in diagnosis, pathogenesis, and treatment of cutaneous leishmaniasis and can be added to the literature.

Impact of Nanotechnology on Differentiation and Augmentation of Stem Cells for Liver Therapy

The liver is one of the crucial organs of the body that performs hundreds of chemical reactions needed by the body to survive. It is also the largest gland of the body. The liver has multiple functions, including the synthesis of chemicals, metabolism of nutrients, and removal of toxins. It also acts as a storage unit. The liver has a unique ability to regenerate itself, but it can lead to permanent damage if the injury is beyond recovery. The only possible treatment of severe liver damage is liver transplant which is a costly procedure and has several other drawbacks. Therefore, attention has been shifted towards the use of stem cells that have shown the ability to differentiate into hepatocytes. Among the numerous kinds of stem cells (SCs), the mesenchymal stem cells (MSCs) are the most famous. Various studies suggest that an MSC transplant can repair liver function, improve the signs and symptoms, and increase the chances of survival. This review discusses the impact of combining stem cell therapy with nanotechnology. By integrating stem cell science and nanotechnology, the information about stem cell differentiation and regulation will increase, resulting in a better comprehension of stem cell-based treatment strategies. The augmentation of SCs with nanoparticles has been shown to boost the effect of stem cell-based therapy. Also, the function of green nanoparticles in liver therapies is discussed.

In Vivo Cellular Magnetic Imaging: Labeled vs. Unlabeled Cells

Superparamagnetic iron oxide (SPIO)-labeling of cells has been applied for magnetic resonance imaging (MRI) cell tracking for over 30 years, having resulted in a dozen or so clinical trials. SPIO nanoparticles are biodegradable and can be broken down into elemental iron, and hence the tolerance of cells to magnetic labeling has been overall high. Over the years, however, single reports have accumulated demonstrating that the proliferation, migration, adhesion and differentiation of magnetically labeled cells may differ from unlabeled cells, with inhibition of chondrocytic differentiation of labeled human mesenchymal stem cells (hMSCs) as a notable example. This historical perspective provides an overview of some of the drawbacks that can be encountered with magnetic labeling. Now that magnetic particle imaging (MPI) cell tracking is emerging as a new in vivo cellular imaging modality, there has been a renaissance in the formulation of SPIO nanoparticles this time optimized for MPI. Lessons learned from the occasional past pitfalls encountered with SPIO-labeling of cells for MRI may expedite possible future clinical translation of (combined) MRI/MPI cell tracking.

Magnetic nanocomposites for biomedical applications

Tissue engineering and regenerative medicine have solved numerous problems related to the repair and regeneration of damaged organs and tissues arising from aging, illnesses, and injuries. Nanotechnology has further aided tissue regeneration science and has provided outstanding opportunities to help disease diagnosis as well as treat damaged tissues. Based on the most recent findings, magnetic nanostructures (MNSs), in particular, have emerged as promising materials for detecting, directing, and supporting tissue regeneration. There have been many reports concerning the role of these nano-building blocks in the regeneration of both soft and hard tissues, but the subject has not been extensively reviewed. Here, we review, classify, and discuss various synthesis strategies for novel MNSs used in medicine. Advanced applications of magnetic nanocomposites (MG-NCs), specifically magnetic nanostructures, are further systematically reviewed. In addition, the scientific and technical aspects of MG-NC used in medicine are discussed considering the requirements for the field. In summary, this review highlights the numerous opportunities and challenges associated with the use of MG-NCs as smart nanocomposites (NCs) in tissue engineering and regenerative medicine.

Targeted trapping of endogenous endothelial progenitor cells for myocardial ischemic injury repair through neutrophil-mediated SPIO nanoparticle-conjugated CD34 antibody delivery and imaging

Endothelia progenitor cell (EPC)-based revascularization therapies have shown promise for the treatment of myocardial ischemic injury. However, applications and efficacy are limited by the relatively inefficient recruitment of endogenous EPCs to the ischemic area, while implantation of exogenous EPCs carries the risk of tumorigenicity. In this study, we developed a therapeutic protocol that relies on the capacity of neutrophils (NEs) to target lesions and release preloaded EPC-binding molecules for high efficiency capture. Neutrophils were loaded with superparamagnetic iron oxide nanoparticles conjugated to an antibody against the EPC surface marker CD34 (SPIO-antiCD34/NEs), and the therapeutic efficacy in ischemic mouse heart following SPIO-antiCD34/NEs injection was monitored by SPIO-enhanced magnetic resonance imaging (MRI). These SPIO-antiCD34/NEs exhibited unimpaired cell viability, superoxide generation, and chemotaxis in vitro as well as satisfactory biocompatibility in vivo. In a mouse model of acute myocardial infarction (MI), SPIO-antiCD34 accumulation could be observed 0.5 h after intravenous injection of SPIO-antiCD34/NEs. Moreover, the degree of CD133⁺ EPC accumulation at MI sites was three-fold higher than in control MI model mice, while ensuing microvessel density was roughly two-fold higher than controls and left ventricular ejection fraction was > 50%. Therapeutic cell biodistribution, MI site targeting, and treatment effects were confirmed by SPIO-enhanced MRI. This study offers a new strategy to improve the endogenous EPC-based myocardial ischemic injury repair through NEs mediated SPIO nanoparticle conjugated CD34 antibody delivery and imaging. STATEMENT OF SIGNIFICANCE: The efficacy of endogenous endothelial progenitor cell (EPC)-based cardiovascular repair therapy for ischemic heart damage is limited by relatively low EPC accumulation at the target site. We have developed a method to improve EPC capture by exploiting the strong targeting ability of neutrophils (NEs) to ischemic inflammatory foci and the capacity of these treated cells to release of preloaded cargo with EPC-binding affinity. Briefly, NEs were loaded with superparamagnetic iron oxide nanoparticles conjugated to an antibody against the EPC surface protein CD34 (SPIO-antiCD34). Thus, we explored sites targeting with nanocomposites cargo for non-invasive EPCs interception and therapy tracking. We demonstrate that SPIO-antiCD34 released from NEs can effectively capture endogenous EPCs and thereby promote heart revascularization and functional recovery in mice. Moreover, the entire process can be monitored by SPIO-enhanced magnetic resonance imaging including therapeutic cell biodistribution, myocardial infarction site targeting, and tissue repair.

Magnetism in Dentistry: Review and Future Perspectives

Tissue engineering or tissue reconstruction/repair/regeneration may be considered as a guiding strategy in oral and maxillofacial surgery, as well as in endodontics, orthodontics, periodontics, and daily clinical practice. A wide range of techniques has been developed over the past years, from tissue grafts to the more recent and innovative regenerative procedures. Continuous research in the field of natural and artificial materials and biomaterials, as well as in advanced scaffold design strategies has been carried out. The focus has also been on various growth factors involved in dental tissue repair or reconstruction. Benefiting from the recent literature, this review paper illustrates current innovative strategies and technological approaches in oral and maxillofacial tissue engineering, trying to offer some information regarding the available scientific data and practical applications. After introducing tissue engineering aspects, an overview on additive manufacturing technologies will be provided, with a focus on the applications of superparamagnetic iron oxide nanoparticles in the biomedical field. The potential applications of magnetic fields and magnetic devices on the acceleration of orthodontic tooth movement will be analysed.

Transplantation of human embryonic stem cells alleviates motor dysfunction in AAV2-Htt171-82Q transfected rat model of Huntington's disease

BACKGROUND

Human embryonic stem cells (hESCs) transplantation had shown to provide a potential source of cells in neurodegenerative disease studies and lead to behavioral recovery in lentivirus transfected or, toxin-induced Huntington's disease (HD) rodent model. Here, we aimed to observe if transplantation of superparamagnetic iron oxide nanoparticle (SPION)-labeled hESCs could migrate in the neural degenerated area and improve motor dysfunction in an AAV2-Htt171-82Q transfected Huntington rat model.

METHODS

All animals were randomly allocated into three groups at first: HD group, sham group, and control group. After six weeks, the animals of the HD group and sham group were again divided into two subgroups depending on animals receiving either ipsilateral or contralateral hESCs transplantation. We performed cylinder test and stepping test every two weeks after AAV2-Htt171-82Q injection and hESCs transplantation. Stem cell tracking was performed once per two weeks using T2 and T2*-weighted images at 4.7 Tesla MRI. We also performed immunohistochemistry and immunofluorescence staining to detect the presence of hESCs markers, huntingtin protein aggregations, and iron in the striatum.

RESULTS

After hESCs transplantation, the Htt virus-injected rats exhibited significant behavioral improvement in behavioral tests. SPION labeled hESCs showed migration with hypointense signal in MRI. The cells were positive with βIII-tubulin, GABA, and DARPP32.

CONCLUSION

Collectively, our results suggested that hESCs transplantation can be a potential treatment for motor dysfunction of Huntington's disease.

1,2-Dimyristoyl-sn-glycero-3-phosphocholine promotes the adhesion of nanoparticles to bio-membranes and transport in rat brain

1,2-Dimyristoyl-sn-glycero-3-phosphocholine (DMPC) coated on the surface of superparamagnetic iron oxide nanoparticles (SPIONs) has advantages in neurotherapy and drug delivery. In this study, the surface of polyvinylpyrrolidone (PVP)-SPIONs was modified with DMPC, then PVP-SPIONs and DMPC/PVP-SPIONs were co-incubated with rat adrenal pheochromocytoma (PC-12) cells to observe the effect of DMPC on the distribution of SPIONs in cells, and further PVP-SPIONs and DMPC/PVP-SPIONs were implanted into the substantia nigra of Sprague-Dawley (SD) rats by stereotaxic injection, and the brain tissues were removed at both twenty-four hours and seven days after injection. The distribution and transport of nanoparticles in the substantia nigra in vivo were explored in these different time periods. The results show that DMPC/PVP-SPIONs were effectively distributed on the membranes of axons, as well as dendritic and myelin sheaths. The attachment of nanoparticles to bio-membranes in the brain could result from similar phospholipid structures of DMPC and the membranes. In addition, DMPC/PVP-SPIONs were transported in the brain faster than those without DMPC. In vitro experiments found that DMPC/PVP-SPIONs enter cells more easily. These characteristics of iron oxide nanoparticles that are modified by phospholipids lead to potential applications in drug delivery or activating neuron membrane channels.

1,2-Dimyristoyl-sn-glycero-3-phosphocholine (DMPC) coated on the surface of superparamagnetic iron oxide nanoparticles (SPIONs) has advantages in neurotherapy and drug delivery.

Biocompatible nanomicelles for sensitive detection and photodynamic therapy of early-stage cancer

The lack of sensitive detection techniques and agents for early-stage tumors, which are characterized by small size, juvenile blood vessels and scarce secreted markers, has hampered timely cancer therapy and human well-being. Herein, the natural product pyropheophorbide-a (PPa) and FDA-approved Pluronic F127 are organized to develop F127-PPa nanomicelles with favorable size, red-shifted fluorescence and decent biocompatibility. After intravenous (i.v.) injection, the F127-PPa nanomicelles could not only accurately identify early-stage xenografted tumors, but also sensitively detect cancer metastasis in lungs through near-infrared (NIR) fluorescence imaging. The fluorescence signals are consistent with radionuclide imaging, photoacoustic (PA) imaging and bioluminescence imaging of tumors, consolidating the reliability of using F127-PPa nanomicelles for sensitive cancer diagnosis in a non-invasive and low-cost manner. Moreover, the fluorescence intensity of small tumors is linearly correlated with the tumoral mass ranging from 10 to 120 mg with a fluorescence coefficient of 4.5 × 10⁷ mg^-1. Under the guidance of multimodal imaging, the tumors could be thoroughly eradicated by F127-PPa under laser irradiation due to efficient reactive oxygen species (ROS) generation. These findings may provide clinically translatable agents and strategies for sensitive diagnosis of early-stage tumors and timely cancer therapy.

In vivo Cell Tracking Using Non-invasive Imaging of Iron Oxide-Based Particles with Particular Relevance for Stem Cell-Based Treatments of Neurological and Cardiac Disease

Stem cell-based therapeutics is a rapidly developing field associated with a number of clinical challenges. One such challenge lies in the implementation of methods to track stem cells and stem cell-derived cells in experimental animal models and in the living patient. Here, we provide an overview of cell tracking in the context of cardiac and neurological disease, focusing on the use of iron oxide-based particles (IOPs) visualized in vivo using magnetic resonance imaging (MRI). We discuss the types of IOPs available for such tracking, their advantages and limitations, approaches for labeling cells with IOPs, biological interactions and effects of IOPs at the molecular and cellular levels, and MRI-based and associated approaches for in vivo and histological visualization. We conclude with reviews of the literature on IOP-based cell tracking in cardiac and neurological disease, covering both preclinical and clinical studies.

An Update on Mesoporous Silica Nanoparticle Applications in Nanomedicine

The efficient and safe delivery of therapeutic drugs, proteins, and nucleic acids are essential for meaningful therapeutic benefits. The field of nanomedicine shows promising implications in the development of therapeutics by delivering diagnostic and therapeutic compounds. Nanomedicine development has led to significant advances in the design and engineering of nanocarrier systems with supra-molecular structures. Smart mesoporous silica nanoparticles (MSNs), with excellent biocompatibility, tunable physicochemical properties, and site-specific functionalization, offer efficient and high loading capacity as well as robust and targeted delivery of a variety of payloads in a controlled fashion. Such unique nanocarriers should have great potential for challenging biomedical applications, such as tissue engineering, bioimaging techniques, stem cell research, and cancer therapies. However, in vivo applications of these nanocarriers should be further validated before clinical translation. To this end, this review begins with a brief introduction of MSNs properties, targeted drug delivery, and controlled release with a particular emphasis on their most recent diagnostic and therapeutic applications.

Nonequilibrium Dynamics of Magnetic Nanoparticles with Applications in Biomedicine

Magnetic nanoparticles are currently the focus of investigation for a wide range of biomedical applications that fall into the categories of imaging, sensing, and therapeutics. A deep understanding of nanoparticle magnetization dynamics is fundamental to optimization and further development of these applications. Here, a summary of theoretical models of nanoparticle dynamics is presented, and computational nonequilibrium models are outlined, which currently represent the most sophisticated methods for modeling nanoparticle dynamics. Nanoparticle magnetization response is explored in depth; the effect of applied field amplitude, as well as nanoparticle size, on the resulting rotation mechanism and timescale is investigated. Two applications in biomedicine, magnetic particle imaging and magnetic fluid hyperthermia, are highlighted.

Effects of labeling human mesenchymal stem cells with superparamagnetic zinc-nickel ferrite nanoparticles on cellular characteristics and adipogenesis/osteogenesis differentiation

OBJECTIVE

An attractive cell source for stem cell-based therapy are WJ-MSCs. Hence, tracking WJ-MSCs using non-invasive imaging procedures (such as MRI) and contrast agents (Zn0.5Ni0.5Fe2O4, NFNPs) are required to evaluate cell distribution, migration, and differentiation.

RESULTS

Results showed that the bare and dextrin-coated NFNPs were internalized inside the WJ-MSCs and had no effect on the cell viability, proliferation, apoptosis, karyotyping, and morphology of WJ-MSCs up to 125 µg/mL. Besides, treated WJ-MSCs were differentiated into osteo/adipocyte-like cells. The expression of RUNX 2, SPP 1 (P < 0.05), and OCN (P > 0.05) genes in the WJ-MSCs treated with dextrin-coated NFNPs was higher than the untreated WJ-MSCs; and the expression of CFD, LPL, and PPAR-γ genes was reduced in WJ-MSCs treated with both NFNPs in comparison with the untreated WJ-MSCs (P > 0.05).

CONCLUSION

Overall, results showed that dextrin-coated NFNPs had no adverse effect on the cellular characteristics, proliferation, and differentiation of WJ-MSCs, and suggesting their potential clinical efficacy.

Deuterium oxide as a contrast medium for real-time MRI-guided endovascular neurointervention

Rationale: Endovascular intervention plays an important role in the treatment of various diseases, in which MRI-guidance can potentially improve precision. However, the clinical applications of currently available contrast media, including Gadolinium-based contrast agents and superparamagnetic iron oxide particles (SPIO), are hindered by safety concerns. In the present study, we sought to develop D2O as a novel contrast agent for guiding endovascular neurointervention. Methods: Animal studies were approved by institutional ACUC and conducted using an 11.7 T Bruker Biospec system and a 3T Siemens Trio clinical scanner for rodent and canine imaging, respectively. The locally selective blood brain barrier opening (BBBO) in rat brains was obtained by intraarterial (IA) injection of mannitol. The dynamic T2w* EPI MRI sequence was used to study the trans-catheter perfusion territory by IA administered SPIO before mannitol administration, whereas a dynamic T1w FLASH sequence was used to acquire Gd contrast-enhanced MRI for assessing BBBO after injection of mannitol. The contrast generated by D2O assessed by either EPI or FLASH methods was compared with the corresponding results assessed by SPIO or Gd. The utility of D2O MRI was also demonstrated to guide drug delivery to glioma in a mouse model. Finally, the clinical utility of D2O-MRI was demonstrated in a canine model. Results: Our study has shown that the contrast generated by D2O can be used to precisely delineate trans-catheter perfusion territory in both small and large animals. The perfusion territories determined by D2O-MRI show moderate correlation with those by SPIO-MRI (Spearman coefficient r = 0.5234, P < 0.001). Moreover, our results show that the perfusion territory determined by D2O-MRI can successfully predict the areas with BBBO after mannitol treatment similar to that assessed by Gd-MRI (Spearman coefficient r = 0.6923, P < 0.001). Using D2O-MRI as imaging guidance, the optimal infusion rate in the mouse brain was determined to be 150 µL/min to maximize the delivery efficacy to the tumor without serious off-target delivery to the brain parenchyma. The enhanced drug delivery of antibodies to the brain tumor was confirmed by fluorescence imaging. Conclusion: Our study demonstrated that D2O can be used as a negative MRI contrast medium to guide endovascular neurointervention. The established D2O -MRI method is safe and quantitative, without the concern of contrast accumulation. These qualities make it an attempting approach for a variety of endovascular procedures.

Gd3+ Doped CoFe2O4 Nanoparticles for Targeted Drug Delivery and Magnetic Resonance Imaging

Nanoparticles of CoGdxFe2 − xO4 (x = 0%, 25%, 50%) synthesized via sol–gel auto combustion technique and encapsulated within a polymer (Eudragit E100) shell containing curcumin by single emulsion solvent evaporation technique were formulated in this study. Testing of synthesized nanoparticles was carried out by using different characterization techniques, to investigate composition, crystallinity, size, morphology, surface charge, functional groups and magnetic properties of the samples. The increased hydrophilicity resulted in sustained drug release of 90.6% and 95% for E1(CoGd0.25Fe1.75O4) and E2(CoGd0.50Fe1.5O4), respectively, over a time span of 24 h. The relaxivities of the best-chosen samples were measured by using a 3T magnetic resonance imaging (MRI) machine, and a high r2/r1 ratio of 43.64 and 23.34 for composition E1(CoGd0.25Fe1.75O4) and E2(CoGd0.50Fe1.5O4) suggests their ability to work as a better T2 contrast agent. Thus, these novel synthesized nanostructures cannot only enable MRI diagnosis but also targeted drug delivery.

Stimuli-Responsive Iron Oxide Nanotheranostics: A Versatile and Powerful Approach for Cancer Therapy

Recent advancements in unravelling elements of cancer biology involved in disease progression and treatment resistance have highlighted the need for a holistic approach to effectively tackle cancer. Stimuli-responsive nanotheranostics based on iron oxide nanoparticles are an emerging class of versatile nanomedicines with powerful capabilities to "seek, sense, and attack" multiple components of solid tumors. In this work, the rationale for using iron oxide nanoparticles and the basic physical principles that impact their function in biomedical applications are reviewed. Subsequently, recent advances in the integration of iron oxide nanoparticles with various stimulus mechanisms to facilitate the development of stimuli-responsive nanotheranostics for application in cancer therapy are summarized. The integration of an iron oxide core with various surface coating mechanisms results in the generation of hybrid nanoconstructs with capabilities to codeliver a wide variety of highly potent anticancer therapeutics and immune modulators. Finally, emerging future directions and considerations for their clinical translation are touched upon.

Fabrication of deferasirox-decorated aptamer-targeted superparamagnetic iron oxide nanoparticles (SPION) as a therapeutic and magnetic resonance imaging agent in cancer therapy

In the current study, the synthesis of a theranostic platform composed of superparamagnetic iron oxide nanoparticles (SPION)-deferasirox conjugates targeted with AS1411 DNA aptamer was reported. In this regard, SPION was amine-functionalized by (3-aminopropyl)trimethoxysilane (ATPMS), and then deferasirox was covalently conjugated onto its surface. Finally, to provide guided drug delivery to cancerous tissue, AS1411 aptamer was conjugated to the complex of SPION-deferasirox. The cellular toxicity assay on CHO, C-26 and AGS cell lines verified higher cellular toxicity of targeted complex in comparison with non-targeted one. The evaluation of in vivo tumor growth inhibitory effect in C26 tumor-bearing mice illustrated that the aptamer-targeted complex significantly enhanced the therapeutic outcome in comparison with both non-targeted complex and free drug. The diagnostic capability of the prepared platform was also evaluated implementing C26-tumor-bearing mice. Obtained data confirmed higher tumor accumulation and higher tumor residence time for targeted complex through MRI imaging due to the existence of SPION as a contrast agent in the core of the prepared complex. The prepared multimodal theranostic system provides a safe and effective platform for fighting against cancer.

Magnetic sensor based on image processing for dynamically tracking magnetic moment of single magnetic mesenchymal stem cell

Developing an economical and universal method to measure the magnetic moments of magnetic mesenchymal stem cells (MSCs) labelled with superparamagnetic iron oxide (SPIO) nanoparticles is crucial for cell tracking. In this study, we used a gradient magnetic field created by a nickel needle to track the motion of cells. A simple and quantifiable magnetic sensor was employed to evaluate the magnetic properties of single viable MSCs. We measured the magnetic moments of microbeads and MSCs using the proposed method and compared the results with magnetic moments measured using a superconducting quantum interference device and with iron contents measured using an inductively coupled plasma spectrometer, respectively. The correlation coefficients indicated satisfactory agreement in both cases, thus confirming the accuracy of the system. By labelling MSCs with SPIOs, we implemented a miniature magnetic sensor to measure the magnetic moments of single magnetic MSCs quantitatively using an image-processing algorithm. Existing methods for the measurement of magnetic moments at the micro/nanoscale have various limitations. Our system realised the measurement of single viable cells, thereby providing a theoretical foundation for the labelling and tracking of MSCs with SPIO nanoparticles. Additionally, the proposed system is both economical and universal.

Multimodal stratified imaging of nanovaccines in lymph nodes for improving cancer immunotherapy

Vaccines hold enormous potential in cancer immunotherapy by stimulating the body's immune response; unfortunately, the clinical response rates of cancer vaccines are less than 30%. Nanovaccines show the potential to enhance the treatment efficacy of conventional vaccines due to their unique properties, such as efficient co-delivery of cocktail to the secondary lymphatic system, high tumor accumulation and penetration, and customizable delivery of antigens and adjuvants. Meanwhile, the non-invasive visualization of vaccines after their delivery can yield information about in vivo distribution and performance, and aid in their subsequent optimization and translational studies. In this review, we summarize the strategies for the spatiotemporal visualization of nanovaccines in lymph nodes, including whole-body in vivo imaging, intravital organ/cell imaging, and ex vivo tissue/cell imaging. The application of imaging modalities in nanovaccine development is discussed. Moreover, strategies to achieve different combinations of imaging modalities are proposed.

Selective anticancer activity of superparamagnetic iron oxide nanoparticles (SPIONs) against oral tongue cancer using in vitro methods: The key role of oxidative stress on cancerous mitochondria

Today, it has been proven that the nanoparticles such as superparamagnetic iron oxide nanoparticles (SPIONs) have widespread use in biomedical applications, for instance, in magnetic resonance imaging and targeted delivery of drugs. Despite many studies on SPIONs in diagnosing some diseases like cancer, it has not been investigated on the oral tongue squamous cell carcinoma (OTSCC) detection by the NPs. Hence, the present study has been designed to assess the in vitro cytotoxicity of SPIONs on the isolated mitochondria of OTSCC by mitochondrial tests. Isolated mitochondria were removed from the separated cancer and control tissues from the squamous cells of tango in male Wistar rats (6 or 8 weeks) and exposed to the different concentrations of SPIONs (30, 60, and 120 nM). A rise in the production of reactive oxygen species is one of the significant mechanisms of this study, followed by a collapse of mitochondrial membrane potential, the escape of mitochondrial cytochrome c, and mitochondrial swelling in the exposed isolated mitochondria of OTSCC with SPIONs. Furthermore, our results indicated that the exposure to the SPIONs reduced the activity of succinate dehydrogenase in complex II of the mitochondria obtained from cancerous oral tongue squamous. So the SPIONs can induce selective cytotoxicity on the OTSCC mitochondria without significant effects on the control mitochondria. Based on the results and further studies about in vivo experiments in this regard, it is concluded the SPIONs may be a hopeful therapeutic candidate for the treatment of OTSCC.

Assessment of proliferation, migration and differentiation potentials of bone marrow mesenchymal stem cells labeling with silica-coated and amine-modified superparamagnetic iron oxide nanoparticles

Superparamagnetic iron oxide nanoparticles have been widely used for cell labeling in preclinical and clinical studies, to improve labeling efficiency, particle conjugation and surface modifications are developed, but some modified SPIONs exert side-effect on physiological activity of cells, which cannot be served as ideal cell tracker. In this study, amine-modified silica-coated SPIO (SPIO@SiO₂-NH₂, SPIO@S-N) nanoparticles were used to label bone marrow derived mesenchymal stem cells (BM-MSCs), then the stem cell potentials were evaluated. It was found BM-MSCs could be efficiently labeled by SPIO@S-N nanoparticles. After labeling, the BM-MSCs viability kept well and the migration ability increased, but the osteogenesis and adipogenesis potentials were not impaired. In steroid associated osteonecrosis (SAON) bone defect model, stem cell implantation was performed by injection of SPIO@S-N labeled BM-MSCs into marrow cavity locally, it was found the SPIO positive cells homed to the periphery of defect region in control group, but were recruited to the defect region in poly lactic-coglycolic acid/tricalcium phosphate (PLGA/TCP) scaffold implantation group. In conclusion, SPIO@S-N nanoparticles promoted migration while retained proliferation and differentiation ability of BM-MSCs, implying this kind of nanoparticles could be served not only an ideal tracking marker but also an accelerator for stem cell homing during tissue repair.

Imaging Guidance for Therapeutic Delivery: The Dawn of Neuroenergetics

Modern neurocritical care relies on ancillary diagnostic testing in the form of multimodal monitoring to address acute changes in the neurological homeostasis. Much of our armamentarium rests upon physiological and biochemical surrogates of organ or regional level metabolic activity, of which a great deal is invested at the metabolic-hemodynamic-hydrodynamic interface to rectify the traditional intermediaries of glucose consumption. Despite best efforts to detect cellular neuroenergetics, current modalities cannot appreciate the intricate coupling between astrocytes and neurons. Invasive monitoring is not without surgical complication, and noninvasive strategies do not provide an adequate spatial or temporal resolution. Without knowledge of the brain's versatile behavior in specific metabolic states (glycolytic vs oxidative), clinical practice would lag behind laboratory empiricism. Noninvasive metabolic imaging represents a new hope in delineating cellular, nigh molecular level energy exchange to guide targeted management in a diverse array of neuropathology.

Projection method as a probe for multiplexing/demultiplexing of magnetically enriched biological tissues

The unmet demand for cheap, accurate, and fast multiplexing of biomarkers has urged nanobiotechnology to prioritize the invention of new biomarkers that make feasible the remote detection, identification, and quantification of biological units, such as regenerative tissues. Here, we introduce a novel approach that highlights magnetic nanowires (MNWs) with such capabilities. This method employs the stable magnetization states of MNWs as a unique characteristic that can be realized by projecting the MNWs' switching field on the backward field (P Hb), also known as the irreversible switching field. Experimentally, several types of MNWs were directly synthesized inside polycarbonate tissues and their P Hb characteristics were measured and analyzed. Our results show that the P Hb gives an excellent identification and quantification characteristic for demultiplexing MNWs embedded in these tissues. Furthermore, this method significantly improves the characterization speed by a factor of 50×-100× that makes it superior to the current state of the art that ceased the progression of magnetic nanoparticles in multiplexing/demultiplexing applications.

Magnetic core-shell nanowires as MRI contrast agents for cell tracking

BACKGROUND

Identifying the precise location of cells and their migration dynamics is of utmost importance for achieving the therapeutic potential of cells after implantation into a host. Magnetic resonance imaging is a suitable, non-invasive technique for cell monitoring when used in combination with contrast agents.

RESULTS

This work shows that nanowires with an iron core and an iron oxide shell are excellent materials for this application, due to their customizable magnetic properties and biocompatibility. The longitudinal and transverse magnetic relaxivities of the core-shell nanowires were evaluated at 1.5 T, revealing a high performance as T2 contrast agents. Different levels of oxidation and various surface coatings were tested at 7 T. Their effects on the T2 contrast were reflected in the tailored transverse relaxivities. Finally, the detection of nanowire-labeled breast cancer cells was demonstrated in T2-weighted images of cells implanted in both, in vitro in tissue-mimicking phantoms and in vivo in mouse brain. Labeling the cells with a nanowire concentration of 0.8 μg of Fe/mL allowed the detection of 25 cells/µL in vitro, diminishing the possibility of side effects. This performance enabled an efficient labelling for high-resolution cell detection after in vivo implantation (~ 10 nanowire-labeled cells) over a minimum of 40 days.

CONCLUSIONS

Iron-iron oxide core-shell nanowires enabled the efficient and longitudinal cellular detection through magnetic resonance imaging acting as T2 contrast agents. Combined with the possibility of magnetic guidance as well as triggering of cellular responses, for instance by the recently discovered strong photothermal response, opens the door to new horizons in cell therapy and make iron-iron oxide core-shell nanowires a promising theranostic platform.

Artificially Engineered Cubic Iron Oxide Nanoparticle as a High-Performance Magnetic Particle Imaging Tracer for Stem Cell Tracking

Stem cell therapies are increasingly recognized as the future direction of regenerative medicine, but the biological fate of the administrated stem cells remains a major concern for clinical translation, which calls for an approach to efficiently monitoring the stem cell behaviors in vivo. Magnetic particle imaging (MPI) is an emerging technology for cell tracking; however, its utility has been largely restricted due to the lack of optimal magnetic nanoparticle tracers. Herein, by controlled engineering of the size and shape of magnetic nanoparticles tailored to MPI physics theory, a specialized MPI tracer, based on cubic iron oxide nanoparticles with an edge length of 22 nm (CIONs-22), is developed. Due to the inherent lower proportion of disordered surface spins, CIONs-22 exhibit significantly larger saturation magnetization than that of spherical ones, while they possess similar saturation magnetization but smaller coercivity compared to larger-sized CIONs. These magnetic properties of CIONs-22 warrant high sensitivity and resolution of MPI. With their efficient cellular uptake, CIONs-22 exhibit superior MPI performance for stem cell labeling and tracking compared to the commercialized tracer Vivotrax. By virtue of these advantages, CIONs-22 enable real-time and prolonged monitoring of the spatiotemporal trajectory of stem cells transplanted to hindlimb ischemia mice, which demonstrates the great potential of CIONs-22 as MPI tracers to advance stem cell therapies.

Recent Advancements of Magnetic Nanomaterials in Cancer Therapy

Magnetic nanomaterials belong to a class of highly-functionalizable tools for cancer therapy owing to their intrinsic magnetic properties and multifunctional design that provides a multimodal theranostics platform for cancer diagnosis, monitoring, and therapy. In this review article, we have provided an overview of the various applications of magnetic nanomaterials and recent advances in the development of these nanomaterials as cancer therapeutics. Moreover, the cancer targeting, potential toxicity, and degradability of these nanomaterials has been briefly addressed. Finally, the challenges for clinical translation and the future scope of magnetic nanoparticles in cancer therapy are discussed.

New Frontiers in Molecular Imaging with Superparamagnetic Iron Oxide Nanoparticles (SPIONs): Efficacy, Toxicity, and Future Applications

Supermagnetic Iron Oxide Nanoparticles (SPIONs) are nanoparticles that have an iron oxide core and a functionalized shell. SPIONs have recently raised much interest in the scientific community, given their exciting potential diagnostic and theragnostic applications. The possibility to modify their surface and the characteristics of their core make SPIONs a specific contrast agent for magnetic resonance imaging but also an intriguing family of tracer for nuclear medicine. An example is 68Ga-radiolabeled bombesin-conjugated to superparamagnetic nanoparticles coated with trimethyl chitosan that is selective for the gastrin-releasing peptide receptors. These receptors are expressed by several human cancer cells such as breast and prostate neoplasia. Since the coating does not interfere with the properties of the molecules bounded to the shell, it has been proposed to link SPIONs with antibodies. SPIONs can be used also to monitor the biodistribution of mesenchymal stromal cells and take place in various applications. The aim of this review of literature is to analyze the diagnostic aspect of SPIONs in magnetic resonance imaging and in nuclear medicine, with a particular focus on sentinel lymph node applications. Moreover, it is taken into account the possible toxicity and the effects on human physiology to determine the SPIONs' safety.

Flexible Ferrofluids: Design and Applications

Ferrofluids, also known as ferromagnetic particle suspensions, are materials with an excellent magnetic response, which have attracted increasing interest in both industrial production and scientific research areas. Because of their outstanding features, such as rapid magnetic reaction, flexible flowability, as well as tunable optical and thermal properties, ferrofluids have found applications in various fields, including material science, physics, chemistry, biology, medicine, and engineering. Here, a comprehensive, in-depth insight into the diverse applications of ferrofluids from material fabrication, droplet manipulation, and biomedicine to energy and machinery is provided. Design of ferrofluid-related devices, recent developments, as well as present challenges and future prospects are also outlined.

Therapeutic applications of multifunctional nanozymes

Nanozymes, which are functional nanomaterials with enzyme-like characteristics, have emerged as a highly-stable and low-cost alternative to natural enzymes. Apart from overcoming the limitations of natural enzymes (e.g., high cost, low stability or complex production), nanozymes are also equipped with the unique intrinsic properties of nanomaterials such as magnetism, luminescence or near infrared absorbance. Therefore, the development of nanozymes exhibiting additional functions to their catalytic activity has opened up new opportunities and applications within the biomedical field. To highlight the progress in the field, this review summarizes the novel applications of multifunctional nanozymes in various biomedical-related fields ranging from cancer diagnosis, cancer and antibacterial therapy to regenerative medicine. Future challenges and perspectives that may advance nanozyme research are also discussed at the end of the review.

Multifunctional magnetic iron oxide nanoparticles: diverse synthetic approaches, surface modifications, cytotoxicity towards biomedical and industrial applications

Magnetic iron oxide nanoparticles (MIONPs) play a major role in the emerging fields of nanotechnology to facilitate rapid advancements in biomedical and industrial platforms. The superparamagnetic properties of MIONPs and their environment friendly synthetic methods with well-defined particle size have become indispensable to obtain their full potential in a variety of applications ranging from cellular to diverse areas of biomedical science. Thus, the broadened scope and need for MIONPs in their demanding fields of applications required to be highlighted for a comprehensive understanding of their state-of-the-art. Many synthetic methods, however, do not entirely abolish their undesired cytotoxic effects caused by free radical production and high iron dosage. In addition, the agglomeration of MIONPs has also been a major problem. To alleviate these issues, suitable surface modification strategies adaptive to MIONPs has been suggested not only for the effective cytotoxicity control but also to minimize their agglomeration. The surface modification using inorganic and organic polymeric materials would represent an efficient strategy to utilize the diagnostic and therapeutic potentials of MIONPs in various human diseases including cancer. This review article elaborates the structural and magnetic properties of MIONPs, specifically magnetite, maghemite and hematite, followed by the important synthetic methods that can be exploited for biomedical approaches. The in vivo cytotoxic effects and the possible surface modifications employed to eliminate the cytotoxicity thereby enhancing the nanoparticle efficacy are also critically discussed. The roles and applications of surface modified MIONPs in medical and industrial platforms have been described for the benefits of global well-being.

Introducing Specificity to Iron Oxide Nanoparticle Imaging by Combining 57Fe-Based MRI and Mass Spectrometry

Iron oxide nanoparticles (ION) are highly sensitive probes for magnetic resonance imaging (MRI) that have previously been used for in vivo cell tracking and have enabled implementation of several diagnostic tools to detect and monitor disease. However, the in vivo MRI signal of ION can overlap with the signal from endogenous iron, resulting in a lack of detection specificity. Therefore, the long-term fate of administered ION remains largely unknown, and possible tissue deposition of iron cannot be assessed with established methods. Herein, we combine nonradioactive ⁵⁷Fe-ION MRI with ex vivo laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) imaging, enabling unambiguous differentiation between endogenous iron (⁵⁶Fe) and iron originating from applied ION in mice. We establish ⁵⁷Fe-ION as an in vivo MRI sensor for cell tracking in a mouse model of subcutaneous inflammation and for assessing the long-term fate of ⁵⁷Fe-ION. Our approach resolves the lack of detection specificity in ION imaging by unambiguously recording a ⁵⁷Fe signature.

Magnetic Nanomaterials for Advanced Regenerative Medicine: The Promise and Challenges

The recent emergence of numerous nanotechnologies is expected to facilitate the development of regenerative medicine, which is a tissue regeneration technique based on the replacement/repair of diseased tissue or organs to restore the function of lost, damaged, and aging cells in the human body. In particular, the unique magnetic properties and specific dimensions of magnetic nanomaterials make them promising innovative components capable of significantly advancing the field of tissue regeneration. Their potential applications in tissue regeneration are the focus here, beginning with the fundamentals of magnetic nanomaterials. How nanomaterials-both those that are intrinsically magnetic and those that respond to an externally applied magnetic field-can enhance the efficiency of tissue regeneration is also described. Applications including magnetically controlled cargo delivery and release, real-time visualization and tracking of transplanted cells, magnetic regulation of cell proliferation/differentiation, and magnetic activation of targeted ion channels and signal pathways involved in regeneration are highlighted, and comments on the perspectives and challenges in magnetic nanomaterial-based tissue regeneration are given.

Superparamagnetic iron oxide nanoparticles (SPIONs) modulate hERG ion channel activity

Superparamagnetic iron oxide nanoparticles (SPIONs) are widely used in various biomedical applications, such as diagnostic agents in magnetic resonance imaging (MRI), for drug delivery vehicles and in hyperthermia treatment of tumors. Although the potential benefits of SPIONs are considerable, there is a distinct need to identify any potential cellular damage associated with their use. Since human ether à go-go-related gene (hERG) channel, a protein involved in the repolarization phase of cardiac action potential, is considered one of the main targets in the drug discovery process, we decided to evaluate the effects of SPIONs on hERG channel activity and to determine whether the oxidation state, the dimensions and the coating of nanoparticles (NPs) can influence the interaction with hERG channel. Using patch clamp recordings, we found that SPIONs inhibit hERG current and this effect depends on the coating of NPs. In particular, SPIONs with covalent coating aminopropylphosphonic acid (APPA) have a milder effect on hERG activity. We observed that the time-course of hERG channel modulation by SPIONs is biphasic, with a transient increase (∼20% of the amplitude) occurring within the first 1-3 min of perfusion of NPs, followed by a slower inhibition. Moreover, in the presence of SPIONs, deactivation kinetics accelerated and the activation and inactivation I-V curves were right-shifted, similarly to the effect described for the binding of other divalent metal ions (e.g. Cd²⁺ and Zn²⁺). Finally, our data show that a bigger size and the complete oxidation of SPIONs can significantly decrease hERG channel inhibition. Taken together, these results support the view that Fe²⁺ ions released from magnetite NPs may represent a cardiac risk factor, since they alter hERG gating and these alterations could compromise the cardiac action potential.

Nanotechnology in regenerative ophthalmology

In recent years, regenerative medicine is gaining momentum and is giving hopes for restoring function of diseased, damaged, and aged tissues and organs and nanotechnology is serving as a catalyst. In the ophthalmology field, various types of allogenic and autologous stem cells have been investigated to treat some ocular diseases due to age-related macular degeneration, glaucoma, retinitis pigmentosa, diabetic retinopathy, and corneal and lens traumas. Nanomaterials have been utilized directly as nanoscaffolds for these stem cells to promote their adhesion, proliferation and differentiation or indirectly as vectors for various genes, tissue growth factors, cytokines and immunosuppressants to facilitate cell reprogramming or ocular tissue regeneration. In this review, we reviewed various nanomaterials used for retina, cornea, and lens regenerations, and discussed the current status and future perspectives of nanotechnology in tracking cells in the eye and personalized regenerative ophthalmology. The purpose of this review is to provide comprehensive and timely insights on the emerging field of nanotechnology for ocular tissue engineering and regeneration.

Targeting tumor cells and neovascularization using RGD-functionalized magnetoliposomes

Purpose

Magnetoliposomes (MLs) have shown great potential as magnetic resonance imaging contrast agents and as delivery vehicles for cancer therapy. Targeting the MLs towards the tumor cells or neovascularization could ensure delivery of drugs at the tumor site. In this study, we evaluated the potential of MLs targeting the αvβ3 integrin overexpressed on tumor neovascularization and different tumor cell types, including glioma and ovarian cancer.

Methods

MLs functionalized with a Texas Red fluorophore (anionic MLs), and with the fluorophore and the cyclic Arginine-Glycine-Aspartate (cRGD; cRGD-MLs) targeting the αvβ3 integrin, were produced in-house. Swiss nude mice were subcutaneously injected with 10⁷ human ovarian cancer SKOV-3 cells. Tumors were allowed to grow for 3 weeks before injection of anionic or cRGD-MLs. Biodistribution of MLs was followed up with a 7T preclinical magnetic resonance imaging (MRI) scanner and fluorescence imaging (FLI) right after injection, 2h, 4h, 24h and 48h post injection. Ex vivo intratumoral ML uptake was confirmed using FLI, electron paramagnetic resonance spectroscopy (EPR) and histology at different time points post injection.

Results

In vivo, we visualized a higher uptake of cRGD-MLs in SKOV-3 xenografts compared to control, anionic MLs with both MRI and FLI. Highest ML uptake was seen after 4h using MRI, but only after 24h using FLI indicating the lower sensitivity of this technique. Furthermore, ex vivo EPR and FLI confirmed the highest tumoral ML uptake at 4 h. Last, a Perl’s stain supported the presence of our iron-based particles in SKOV-3 xenografts.

Conclusion

Uptake of cRGD-MLs can be visualized using both MRI and FLI, even though the latter was less sensitive due to lower depth penetration. Furthermore, our results indicate that cRGD-MLs can be used to target SKOV-3 xenograft in Swiss nude mice. Therefore, the further development of this particles into theranostics would be of interest.

Magnetic Composite Biomaterials for Neural Regeneration

Nervous system damage caused by physical trauma or degenerative diseases can result in loss of sensory and motor function for patients. Biomaterial interventions have shown promise in animal studies, providing contact guidance for extending neurites or sustained release of various drugs and growth factors; however, these approaches often target only one aspect of the regeneration process. More recent studies investigate hybrid approaches, creating complex materials that can reduce inflammation or provide neuroprotection in addition to stimulating growth and regeneration. Magnetic materials have shown promise in this field, as they can be manipulated non-invasively, are easily functionalized, and can be used to mechanically stimulate cells. By combining different types of biomaterials (hydrogels, nanoparticles, electrospun fibers) and incorporating magnetic elements, magnetic materials can provide multiple physical and chemical cues to promote regeneration. This review, for the first time, will provide an overview of design strategies for promoting regeneration after neural injury with magnetic biomaterials.

Advances of nanotechnology in osteochondral regeneration

In the past few decades, nanotechnology has proven to be one of the most powerful engineering strategies. The nanotechnologies for osteochondral tissue engineering aim to restore the anatomical structures and physiological functions of cartilage, subchondral bone, and osteochondral interface. As subchondral bone and articular cartilage have different anatomical structures and the physiological functions, complete healing of osteochondral defects remains a great challenge. Considering the limitation of articular cartilage to self-healing and the complexity of osteochondral tissue, osteochondral defects are in urgently need for new therapeutic strategies. This review article will concentrate on the most recent advancements of nanotechnologies, which facilitates chondrogenic and osteogenic differentiation for osteochondral regeneration. Moreover, this review will also discuss the current strategies and physiological challenges for the regeneration of osteochondral tissue. Specifically, we will summarize the latest developments of nanobased scaffolds for simultaneously regenerating subchondral bone and articular cartilage tissues. Additionally, perspectives of nanotechnology in osteochondral tissue engineering will be highlighted. This review article provides a comprehensive summary of the latest trends in cartilage and subchondral bone regeneration, paving the way for nanotechnologies in osteochondral tissue engineering. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement.