Magnetic CoPt nanoparticles as MRI contrast agent for transplanted neural stem cells detection

Strategies, Challenges, and Prospects of Nanoparticles in Gynecological Malignancies

Gynecologic cancers are a significant health issue for women globally. Early detection and successful treatment of these tumors are crucial for the survival of female patients. Conventional therapies are often ineffective and harsh, particularly in advanced stages, necessitating the exploration of new therapy options. Nanotechnology offers a novel approach to biomedicine. A novel biosensor utilizing bionanotechnology can be employed for early tumor identification and therapy due to the distinctive physical and chemical characteristics of nanoparticles. Nanoparticles have been rapidly applied in the field of gynecologic malignancies, leading to significant advancements in recent years. This study highlights the significance of nanoparticles in treating gynecological cancers. It focuses on using nanoparticles for precise diagnosis and continuous monitoring of the disease, innovative imaging, and analytic methods, as well as multifunctional drug delivery systems and targeted therapies. This review examines several nanocarrier systems, such as dendrimers, liposomes, nanocapsules, and nanomicelles, for gynecological malignancies. The review also examines the enhanced therapeutic potential and targeted delivery of ligand-functionalized nanoformulations for gynecological cancers compared to nonfunctionalized anoformulations. In conclusion, the text also discusses the constraints and future exploration prospects of nanoparticles in chemotherapeutics. Nanotechnology will offer precise methods for diagnosing and treating gynecological cancers.

Investigation of gadolinium doped manganese nano spinel ferrites via magnetic hypothermia therapy effect towards MCF-7 breast cancer

Magnetic spinel ferrite nanoparticles (MSF-NPs) are potential candidates for biomedical applications, especially in cancer diagnosis and therapy due to their excellent physiochemical and magnetic properties. In the current study, MSF-NPs were fabricated by sol-gel auto combustion method. The crystal structure and surface morphology were confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The magnetic properties were studied by VSM (vibrating sample magnetometer). As increasing Gd3+ concentration, the saturation magnetization values decreased from (17.8-2.3) emu/g, while the coercivity decreased from (499-133) Oe at room temperature. Finally, the fabricated MSF-NPs were tested against anticancer activity by MTT assay. The IC50 = 21.27 μg/mL value was observed, showing the strong antiproliferative activity of these nanoparticles. These results suggested that the obtained MSF-NPs would be useful for remote-controlled hyperthermia therapy for cancer treatment and MRI application due to their excellent magnetic properties. These distinct properties make MSF-NPs most suitable for cancer treatment and bright Contrast Agents (T1-MRI).

Chitosan nanoparticle toxicity: A comprehensive literature review of in vivo and in vitro assessments for medical applications

Topic definition

This literature review aims to update the current knowledge on toxicity of chitosan nanoparticles, compare the recent findings and identify the gaps with knowledge that is present for the chitosan nanoparticles.

Methods

The publications between 2010 and 2020 were searched in Science Direct, Pubmed.gov, Google Scholar, Research Gate, and ClinicalTrials.gov, according to the inclusion and exclusion criteria. 30 primary research studies were obtained from the literature review to compare the in vitro in vivo toxicity profiles among the chitosan nanoparticles.

Major highlights

Chitosan nanoparticles and other types of nanoparticles show cytotoxic effects on cancer cells while having minimal toxicity on normal cells. This apparent effect poses some considerations for use in incorporating cancer therapeutics into chitosan nanoparticles as an administration form. The concentration, duration of exposure, and pH of the solution can influence nanoparticle cytotoxicity, particularly in zebrafish. Different cell lines exhibit varying degrees of toxicity when exposed to nanoparticles, and of note are liver cells that show toxicity under exposure as indicated by increased alanine transaminase (ALT) levels. Aside from ALT, platelet aggregation can be considered a toxicity induced by chitosan nanoparticles. In addition, zebrafish cells experience the most toxicity, including organ damage, neurobehavioral impairment, and developmental abnormalities, when exposed to nanoparticles. However, nanoparticles may exhibit different toxicity profiles in different organisms, with brain toxicity and liver toxicity being present in zebrafish but not rats. Different organs exhibit varying degrees of toxicity, with the eye and mouth apparently having the lowest toxicity, while the brain, intestine, muscles and lung showing mixed results. Cardiotoxicity induced by chitosan nanoparticles was not observed in zebrafish embryos, and nanoparticles may reduce cardiotoxicity when delivering drug. Toxicity found in an organ may not necessarily mean that it is toxic towards all the cells found in that organ, as muscle toxicity was present when tested in zebrafish but not in C2C12 myoblast cells. Some of the studies conducted may have limitations that need to be reconsidered to account for differing results, with some examples being two experiments done on HeLa cells where one study concluded chitosan nanoparticles were toxic to the cells while the other seems to have no toxicity present. With regards to LD50, one study has stated the concentration of 64.21 mg/ml was found. Finally, smaller nanoparticles generally exhibit higher toxicity in cells compared to larger nanoparticles.

Scope for future work

This literature review did not uncover any published clinical trials with available results. Subsequent research endeavors should prioritize conducting clinical trials involving human volunteers to directly assess toxicity, rather than relying on cell or animal models.

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.

Biomimetic mineralization based on self-assembling peptides

Biomimetic science has attracted great interest in the fields of chemistry, biology, materials science, and energy. Biomimetic mineralization is the process of synthesizing inorganic minerals under the control of organic molecules or biomolecules under mild conditions. Peptides are the motifs that constitute proteins, and can self-assemble into various hierarchical structures and show a high affinity for inorganic substances. Therefore, peptides can be used as building blocks for the synthesis of functional biomimetic materials. With the participation of peptides, the morphology, size, and composition of mineralized materials can be controlled precisely. Peptides not only provide well-defined templates for the nucleation and growth of inorganic nanomaterials but also have the potential to confer inorganic nanomaterials with high catalytic efficiency, selectivity, and biotherapeutic functions. In this review, we systematically summarize research progress in the formation mechanism, nanostructural manipulation, and applications of peptide-templated mineralized materials. These can further inspire researchers to design structurally complex and functionalized biomimetic materials with great promising applications.

Effect of the Preparation Conditions on the Catalytic Properties of CoPt for Highly Efficient 4-Nitrophenol Reduction

CoPt alloys with Pt contents from 15 to 90% were prepared using low-cost electrochemical deposition. Different samples were synthesized from electrochemical baths at pH = 2.5 and 5.5 in a solution with and without saccharin as an additive. The morphology, composition and crystalline structure of the as-prepared samples were investigated by High Resolution-Scanning Electron Microscopy (HR-SEM), Atomic Force Microscopy (AFM), Ultra-high Resolution-Transmission Electron Microscopy (UHR-TEM), Energy-Dispersive X-ray Spectroscopy (EDX), and X-ray Diffraction (XRD). XRD investigations revealed that fcc crystalline structure transforms into hcp crystalline structure when the pH of the electrochemical bath is increased from 2.5 to 5.5 as well as when saccharin is added to the electrochemical bath. The catalytic performance of the CoPt alloys for the nitro to amino phenol compounds conversion was investigated for all the prepared samples, and the results show that the conversion degree increases (from 11.4 to 96.5%) even though the Pt content in the samples decreases. From the samples prepared from the electrochemical bath with saccharin, a study regarding the effect of contact time was performed. The results indicated that after only 5 min, the CoPt sample prepared at pH = 5.5 in the presence of saccharin completely converted the nitro compound to an amino compound.

Nanomedicine in Neuroscience: An Application Towards the Treatment of Various Neurological Diseases

Absatract:

The effectiveness, cell viability, and selective delivery of medications and diagnostic substances to target organs, tissues, and organs are typical concerns in the care and prognosis of many illnesses. Neurological diseases pose complex challenges, as cerebral targeting represents a yet unresolved challenge in pharmacotherapy, owing to the blood-brain boundary, a densely com-pacted membrane of endothelial cells that prohibits undesired chemicals from reaching the brain. Engineered nanoparticles, with dimensions ranging from 1 to 100 nm, provide intriguing biomedi-cal techniques that may allow for resolving these issues, including the ability to cross the blood-brain barrier. It has substantially explored nanoparticles in the previous century, contributing to sub-stantial progress in biomedical studies and medical procedures. Using many synthesized nanoparti-cles on the molecular level has given many potential gains in various domains of regenerative medi-cine, such as illness detection, cascaded cell treatment, tissue regeneration, medication, and gene editing. This review will encapsulate the novel developments of nanostructured components used in neurological diseases with an emphasis on the most recent discoveries and forecasts for the future of varied biological nanoparticles for tissue repair, drug inventions, and the synthesizing of the deliv-ery mechanism.

Sensitization of glioblastoma cancer cells to radiotherapy and magnetic hyperthermia by targeted temozolomide-loaded magnetite tri-block copolymer nanoparticles as a nanotheranostic agent

AIMS

Recently, the development of new strategies in the treatment and diagnosis of cancer cells such as thermo-radiation-sensitizer and theranostic agents have received a great deal of attention. In this work, folic acid-conjugated temozolomide-loaded SPION@PEG-PBA-PEG nanoparticles (TMZ-MNP-FA NPs) were proposed for use as magnetic resonance imaging (MRI) contrast agents and to enhance the cytotoxic effects of hyperthermia and radiotherapy.

MAIN METHODS

Nanoparticles were synthesized by the Nano-precipitation method and their characteristics were determined by dynamic light scattering (DLS), scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). To evaluate the thermo-radio-sensitization effects of NPs, C6 cells were treated with nanoparticles for 24 h and then exposed to 6-MV X-ray radiation. After radiotherapy, the cells were subjected to an alternating magnetic field (AMF) hyperthermia. The therapeutic potential was assessed using clonogenic assay, ROS generation measurement, flow cytometry assay, and qRT-PCR analysis. Also, the diagnostic properties of the nanoparticles were assessed by MRI.

KEY FINDINGS

MRI scanning indicated that nanoparticles accumulated in C6 cells could be tracked by T2-weighted MR imaging. Colony formation assay proved that TMZ-MNP-FA NPs enhanced the anti-proliferation effects of AMF by 1.94-fold compared to AMF alone (P < 0.0001). Moreover, these NPs improved the radiation effects with a dose enhancement factor of 1.65. All results showed that the combination of carrier-based chemotherapy with hyperthermia and radiotherapy caused a higher anticancer efficacy than single- or two-modality treatments.

SIGNIFICANCE

The nanoparticles advanced in this study can be proposed as the promising theranostic and thermo-radio-sensitizer platform for the diagnosis and tri-modal synergistic cancer therapy.

Low-energy configurations of Pt6Cu6 clusters and their physical-chemical characterization: a high-accuracy DFT study

Based on a combination of many-body potentials, an analysis of the inertia tensors and a Density Functional Theory framework, we use a method to harvest the lowest energy states of any set of cluster systems. Then, this methodology is applied to the Pt₆Cu₆ cluster case and the structural, chemical, electronic, anisotropy, magnetic and vibrational properties of the lowest energy isomers are studied. Unexpectedly, some tens of isomers with much lower energy than the precedent believed ground state [J. Chem. Phys., 131(4):044701] are found, which indicates the goodness of this methodology. Some of the isomers obtained present the point groups C_s, C_2v according to Schoenflies notation, while others do not exhibit specific symmetry operations. The global chemical descriptors as the ionization potential, the electron affinity and the chemical hardness have oscillating behaviors with overall decreasing trends as the energy of the isomer grows up, indicating a higher rate of deactivation by sintering processes and a higher strength of the adsorption of small molecules on these systems. We present interesting results of the electronic, magnetic, anisotropy, vibrational and thermal properties of these clusters and discuss them; what can be useful information for future experiments and technical applications in varied fields as catalysis, spintronics, molecular magnetism or magnetic storage information.

Monodispersed AgNPs Synthesized from the Nanofactories of Theobroma cacao (Cocoa) Leaves and Pod Husk and Their Antimicrobial Activity

Silver nanoparticles (AgNPs) have been synthesized from the more chemically rich and diverse cocoa pod; the synthesis of silver nanoparticles from cocoa leaves, which are less rich and have low diversity in bioactive molecules, is yet to be achieved. In this work, AgNPs produced using the extracts of the cocoa leaf (CL) and cocoa pods (CP) have been investigated and their antimicrobial activity against E. coli was evaluated. UV-visible absorption spectroscopy was used to examine the reduction of silver ions in solution and the surface plasmon resonance of AgNPs. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were used to further characterize the nanoparticles. The crystalline nature of AgNPs was confirmed by XRD, and the purity and presence of elemental silver were determined by EDX. CL-AgNPs were observed to have a surface plasmon resonance of 425 nm, while CP-AgNPs had a surface plasmon resonance of 440 nm. CL-AgNPs had a significantly higher purity than CP-AgNPs. With a shorter nucleation time, the intensity of the UV-Vis spectrum was always higher in the case of CL-AgNPs, indicating a larger population of bioactive molecules available for CL-AgNPs synthesis. FTIR confirmed the presence of phenolic compounds in the leaf and pod extract, implying that water-soluble polyphenolic and flavonoid chemicals are responsible for nanoparticle reduction, capping, and stability. AgNPs generated from CL and CP extracts are polydispersed, with particle sizes of 10–110 nm and 20–680 nm, respectively, according to DLS. The corresponding zeta potentials measured are −2.7 mV for CL-AgNPs and −0.93 mV for CP-AgNPs. The zeta potential values suggest that the particles have long-term stability. Furthermore, CL-AgNPs outperformed CP-AgNPs in terms of antibacterial activity against Escherichia coli. CL-AgNPs were found to have a maximal inhibitory zone of 21 mm.

Nanocarriers-Mediated Drug Delivery Systems for Anticancer Agents: An Overview and Perspectives

Nanotechnology has been actively integrated as drug carriers over the last few years to treat various cancers. The main hurdle in the clinical management of cancer is the development of multidrug resistance against chemotherapeutic agents. To overcome the limitations of chemotherapy, the researchers have been developing technological advances for significant progress in the oncotherapy by enabling the delivery of chemotherapeutic agents at increased drug content levels to the targeted spots. Several nano-drug delivery systems designed for tumor-targeting are evaluated in preclinical and clinical trials and showed promising outcomes in cancerous tumors' clinical management. This review describes nanocarrier's importance in managing different types of cancers and emphasizing nanocarriers for drug delivery and cancer nanotherapeutics. It also highlights the recent advances in nanocarriers-based delivery systems, including polymeric nanocarriers, micelles, nanotubes, dendrimers, magnetic nanoparticles, solid lipid nanoparticles, and quantum dots (QDs). The nanocarrier-based composites are discussed in terms of their structure, characteristics, and therapeutic applications in oncology. To conclude, the challenges and future exploration opportunities of nanocarriers in chemotherapeutics are also presented.

Shape transformation and self-alignment of Fe-based nanoparticles

New types of functional material structures will emerge if the shape and properties are controlled in three-dimensional nanodevices. Possible applications of these would be nanoelectronics and medical systems. Magnetic nanoparticles (MNPs) are especially important in electronics such as magnetic storage, sensors, and spintronics. Also, in those that are used as magnetic resonance imaging contrasts, and tissue specific therapeutic agents, as well as in the labeling and sorting of cells, drug delivery, separation of biochemical products, and in other medical applications. Most of these applications require MNPs to be chemically stable, uniform in size, and controllable in terms of their magnetic properties and shape. In this paper three new functions of iron (Fe)-based nanoparticles are reported: shape transformation, oxidation prevention, and self-alignment. The shape of the Fe nanoparticles could be controlled by changing their oxidation states and properties by using a nanocarbon coating. Full field X-ray microscopy using synchrotron radiation revealed controllable magnetic properties of MNPs at the L₃ edge which depended on the oxidation states. Then, inkjet printing was successfully performed to deposit a uniform layer of MNPs by the size.

Nanomaterial-involved neural stem cell research: Disease treatment, cell labeling, and growth regulation

Neural stem cells (NSCs) have been widely investigated for their potential in the treatment of various diseases and transplantation therapy. However, NSC growth regulation, labeling, and its application to disease diagnosis and treatment are outstanding challenges. Recently, nanomaterials have shown promise for various applications including genetic modification, imaging, and controlled drug release. Here we summarize the recent progress in the use of nanomaterials in combination with NSCs for disease treatment and diagnosis, cell labeling, and NSC growth regulation. The toxicity of nanomaterials to NSCs is also discussed.

Manganese doped-iron oxide nanoparticle clusters and their potential as agents for magnetic resonance imaging and hyperthermia

A simple, one pot method to synthesize water-dispersible Mn doped iron oxide colloidal clusters constructed of nanoparticles arranged into secondary flower-like structures was developed. This method allows the successful incorporation and homogeneous distribution of Mn within the nanoparticle iron oxide clusters. The formed clusters retain the desired morphological and structural features observed for pure iron oxide clusters, but possess intrinsic magnetic properties that arise from Mn doping. They show distinct performance as imaging contrast agents and excellent characteristics as heating mediators in magnetic fluid hyperthermia. It is expected that the outcomes of this study will open up new avenues for the exploitation of doped magnetic nanoparticle assemblies in biomedicine.

High magnetisation, monodisperse and water-dispersible CoFe@Pt core/shell nanoparticles

High magnetisation and monodisperse CoFe alloy nanoparticles are desired for a wide range of biomedical applications. However, these CoFe nanoparticles are prone to oxidation, resulting in the deterioration of their magnetic properties. In the current work, CoFe alloy nanoparticles were prepared by thermal decomposition of cobalt and iron carbonyls in organic solvents at high temperatures. Using a seeded growth method, we successfully synthesised chemically stable CoFe@Pt core/shell nanostructures. The obtained core/shell nanoparticles have high saturation magnetisation up to 135 emu g^-1. The magnetisation value of the core/shell nanoparticles remains 93 emu g^-1 after being exposed to air for 12 weeks. Hydrophobic CoFe@Pt nanoparticles were rendered water-dispersible by encapsulating with poly(maleic anhydride-alt-1-octadecene) (PMAO). These nanoparticles were stable in water for at least 3 months and in a wide range of pH from 2 to 11.

Magnetic CoPt nanoparticle-decorated ultrathin Co(OH)2 nanosheets: an efficient bi-functional water splitting catalyst

Magnetic CoPt bimetallic NPs anchored on ultrathin Co(OH)₂ nanosheet arrays functioned as an efficient bi-functional water splitting catalyst where the intrinsic magnetism of CoPt was used to improve the stability further by providing external magnetic support.

Nanoparticle Technologies in the Spinal Cord

Nanoparticles are increasingly being studied within experimental models of spinal cord injury (SCI). They are used to image cells and tissue, move cells to specific regions of the spinal cord, and deliver therapeutic agents locally. The focus of this article is to provide a brief overview of the different types of nanoparticles being studied for spinal cord applications and present data showing the capability of nanoparticles to deliver the chondroitinase ABC (chABC) enzyme locally following acute SCI in rats. Nanoparticles releasing chABC helped promote axonal regeneration following injury, and the nanoparticles also protected the enzyme from rapid degradation. In summary, nanoparticles are viable materials for diagnostic or therapeutic applications within experimental models of SCI and have potential for future clinical use.

Stimuli-responsive magnetic nanoparticles for tumor-targeted bimodal imaging and photodynamic/hyperthermia combination therapy

Despite magnetic nanoparticles having shown great potential in cancer treatment, tremendous challenges related to diagnostic sensitivity and treatment efficacy for clinical application remain. Herein, we designed optimized multifunctional magnetite nanoparticles (AHP@MNPs), composed of Fe3O4 nanoparticles and photosensitizer conjugated hyaluronic acid (AHP), to achieve enhanced tumor diagnosis and therapy. Fe3O4 nanoparticles (MNPs) were synthesized by a facile hydrolysis method. MNPs have higher biocompatibility, controllable particle sizes, and desirable magnetic properties. The fabricated AHP@MNPs have enhanced water solubility (average size: 108.13 ± 1.08 nm), heat generation properties, and singlet oxygen generation properties upon magnetic and laser irradiation. The AHP@MNPs can target tumors via CD44 receptor-mediated endocytosis, which have enhanced tumor therapeutic effects through photodynamic/hyperthermia-combined treatment without any drugs. We successfully detected tumors implanted in mice via magnetic resonance imaging and optical imaging. Furthermore, we demonstrated the photodynamic/hyperthermia-combined therapeutic efficacy of AHP@MNPs with synergistically enhanced efficacy against cancer.

Iron oxide nanoparticles for neuronal cell applications: uptake study and magnetic manipulations

Background

The ability to direct and manipulate neuronal cells has important potential in therapeutics and neural network studies. An emerging approach for remotely guiding cells is by incorporating magnetic nanoparticles (MNPs) into cells and transferring the cells into magnetic sensitive units. Recent developments offer exciting possibilities of magnetic manipulations of MNPs-loaded cells by external magnetic fields. In the present study, we evaluated and characterized uptake properties for optimal loading of cells by MNPs. We examined the interactions between MNPs of different cores and coatings, with primary neurons and neuron-like cells.

Results

We found that uncoated-maghemite iron oxide nanoparticles maximally interact and penetrate into cells with no cytotoxic effect. We observed that the cellular uptake of the MNPs depends on the time of incubation and the concentration of nanoparticles in the medium. The morphology patterns of the neuronal cells were not affected by MNPs uptake and neurons remained electrically active. We theoretically modeled magnetic fluxes and demonstrated experimentally the response of MNP-loaded cells to the magnetic fields affecting cell motility. Furthermore, we successfully directed neurite growth orientation along regeneration.

Conclusions

Applying mechanical forces via magnetic mediators is a useful approach for biomedical applications. We have examined several types of MNPs and studied the uptake behavior optimized for magnetic neuronal manipulations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12951-016-0190-0) contains supplementary material, which is available to authorized users.

Plant Polyphenol-Assisted Green Synthesis of Hollow CoPt Alloy Nanoparticles for Dual-Modality Imaging Guided Photothermal Therapy

Theranostic nanomedicines that integrate diagnostic and therapeutic moieties into a single nanoscale platform are playing an increasingly important role in fighting cancer. Here, a facile and green synthetic strategy for hollow CoPt alloy nanoparticles (HCPA-NPs) using plant polyphenols as assisted agents is reported for the first time. This novel strategy enables size-controlled synthesis of HCPA-NPs through the control of the molecular sizes of polyphenols. It is also a versatile strategy for synthesizing other hollow alloy nanoparticles with various metal compositions due to the diverse metal-chelating ability of the polyphenols. Further studies show that HCPA-NPs have good biocompatibility and can be successfully implemented for magnetic resonance and photoacoustic dual-modal imaging guided photothermal therapy. This work brings new insights for the green synthesis of hollow nanoparticles and extends these biocompatible nanoparticles for theranostic applications.

Bio-distribution and in vivo/in vitro toxicity profile of PEGylated polymer capsules encapsulating LaVO4:Tb3+ nanoparticles for bioimaging applications

Lanthanide-doped nanoparticles are being explored for bioimaging applications owing to their unique optical properties.

Short peptide mediated self-assembly of platinum nanocrystals with selective spreading property

Nanosize spherical assemblies of platinum nanocrystals with core/shell configurations and selective spreading properties are prepared through short peptide mediation.

Nanotechnology for the detection and therapy of stroke

Over the years, nanotechnology has greatly developed, moving from careful design strategies and synthesis of novel nanostructures to producing them for specific medical and biological applications. The use of nanotechnology in diagnostics, drug delivery, and tissue engineering holds great promise for the treatment of stroke in the future. Nanoparticles are employed to monitor grafted cells upon implantation, or to enhance the imagery of the tissue, which is coupled with a noninvasive imaging modality such as magnetic resonance imaging, computed axial tomography or positron emission tomography scan. Contrast imaging agents used can range from iron oxide, perfluorocarbon, cerium oxide or platinum nanoparticles to quantum dots. The use of nanomaterial scaffolds for neuroregeneration is another area of nanomedicine, which involves the creation of an extracellular matrix mimic that not only serves as a structural support but promotes neuronal growth, inhibits glial differentiation, and controls hemostasis. Promisingly, carbon nanotubes can act as scaffolds for stem cell therapy and functionalizing these scaffolds may enhance their therapeutic potential for treatment of stroke. This Progress Report highlights the recent developments in nanotechnology for the detection and therapy of stroke. Recent advances in the use of nanomaterials as tissue engineering scaffolds for neuroregeneration will also be discussed.

Ultrasmall superparamagnetic iron oxide nanoparticle prelabelling of human neural precursor cells

Stem cells prelabelled with iron oxide nanoparticles can be visualised using magnetic resonance imaging (MRI). This technique allows for noninvasive long-term monitoring of migration, integration and stem cell fate following transplantation into living animals. In order to determine biocompatibility, the present study investigated the biological impact of introducing ultrasmall superparamagnetic iron oxide nanoparticles (USPIOs) into primary human fetal neural precursor cells (hNPCs) in vitro. USPIOs with a mean diameter of 10-15 nm maghemite iron oxide core were sterically stabilised by 95% methoxy-poly(ethylene glycol) (MPEG) and either 5% cationic (NH2) end-functionalised, or 5% Rhodamine B end-functionalised, polyacrylamide. The stabilising polymer diblocks were synthesised by reversible addition-fragmentation chain transfer (RAFT) polymerisation. Upon loading, cellular viability, total iron capacity, differentiation, average distance of migration and changes in intracellular calcium ion concentration were measured to determine optimal loading conditions. Taken together we demonstrate that prelabelling of hNPCs with USPIOs has no significant detrimental effect on cell biology and that USPIOs, when utilised at an optimised dosage, are an effective means of noninvasively tracking prelabelled hNPCs.

A facile single-step synthesis of ternary multicore magneto-plasmonic nanoparticles

We report a facile single-step synthesis of ternary hybrid nanoparticles (NPs) composed of multiple dumbbell-like iron-silver (FeAg) cores encapsulated by a silicon (Si) shell using a versatile co-sputter gas-condensation technique. In comparison to previously reported binary magneto-plasmonic NPs, the advantage conferred by a Si shell is to bind the multiple magneto-plasmonic (FeAg) cores together and prevent them from aggregation at the same time. Further, we demonstrate that the size of the NPs and number of cores in each NP can be modulated over a wide range by tuning the experimental parameters.

Stem cell tracking using iron oxide nanoparticles

Superparamagnetic iron oxide nanoparticles (SPIONs) are an exciting advancement in the field of nanotechnology. They expand the possibilities of noninvasive analysis and have many useful properties, making them potential candidates for numerous novel applications. Notably, they have been shown that they can be tracked by magnetic resonance imaging (MRI) and are capable of conjugation with various cell types, including stem cells. In-depth research has been undertaken to establish these benefits, so that a deeper level of understanding of stem cell migratory pathways and differentiation, tumor migration, and improved drug delivery can be achieved. Stem cells have the ability to treat and cure many debilitating diseases with limited side effects, but a main problem that arises is in the noninvasive tracking and analysis of these stem cells. Recently, researchers have acknowledged the use of SPIONs for this purpose and have set out to establish suitable protocols for coating and attachment, so as to bring MRI tracking of SPION-labeled stem cells into common practice. This review paper explains the manner in which SPIONs are produced, conjugated, and tracked using MRI, as well as a discussion on their limitations. A concise summary of recently researched magnetic particle coatings is provided, and the effects of SPIONs on stem cells are evaluated, while animal and human studies investigating the role of SPIONs in stem cell tracking will be explored.

Protein A-conjugated iron oxide nanoparticles for separation ofVibrio choleraefrom water samples

Pathogen separation is of great significance for precise detection and prevention of disease outbreaks. For the first time, protein A conjugated with chitosan-coated iron oxide nanoparticles was prepared for pathogen separation at low concentrations from liquid samples.Vibrio choleraeO1 (VO1) bacteria were used for testing the effectiveness of this conjugate. Transmission electron microscopy (TEM) was used to confirm the presence of captured VO1. The results showed that, after binding with a specific antibody, the conjugate allows separation of VO1 bacteria from water samples at a concentration as low as 10 cfu mL⁻¹. Moreover, the conjugate can be used in parallel with conventional or modern diagnostic tests for quick and accurate detection of pathogens.

Magnetic PEGylated Pt3Co nanoparticles as a novel MR contrast agent: in vivo MR imaging and long-term toxicity study

Magnetic resonance (MR) imaging using magnetic nanoparticles as the contrast agent has been extensively explored in biomedical imaging and disease diagnosis. Herein, we develop biocompatible polymer coated ultra-small Pt3Co magnetic nanoparticles as a new T2-weighted MR imaging contrast agent. A unique class of alloy Pt3Co nanoparticles is synthesized through a thermal decomposition method. After being modified with polyethylene glycol (PEG), the obtained Pt3Co-PEG nanoparticles exhibit an extremely high T2-weighted relaxivity rate (r2) up to 451.2 mM s(-1), which is much higher than that of Resovist®, a commercial T2-MR contrast agent used in the clinic. In vitro experiments indicate no obvious cytotoxicity of Pt3Co-PEG nanoparticles to various cell lines. After intravenous injection of Pt3Co-PEG nanoparticles, in vivo T2-weighted MR imaging of tumor-bearing mice reveals strong tumor contrast, which is much higher than that offered by injecting Resovist®. We further study the long-term biodistribution and toxicology of this new type of MR contrast nanoparticles after intravenous injection into healthy mice. Despite the significant retention of Pt3Co-PEG nanoparticles in the mouse liver and spleen, no appreciable toxicity of these nanoparticles to the treated animals has been noted in our detailed histological and hematological analysis over a course of 60 days. Our work demonstrates that functionalized Pt3Co nanoparticles may be a promising new type of T2-weighted MR contrast agent potentially useful in biomedical imaging and diagnosis.

Tracking stem cells in tissue-engineered organs using magnetic nanoparticles

The use of human stem cells (SCs) in tissue engineering holds promise in revolutionising the treatment of numerous diseases. There is a pressing need to comprehend the distribution, movement and role of SCs once implanted onto scaffolds. Nanotechnology has provided a platform to investigate this through the development of inorganic magnetic nanoparticles (MNPs). MNPs can be used to label and track SCs by magnetic resonance imaging (MRI) since this clinically available imaging modality has high spatial resolution. In this review, we highlight recent applications of iron oxide and gadolinium based MNPs in SC labelling and MRI; and offer novel considerations for their future development.

Magnetic nanoparticles as new diagnostic tools in medicine

Magnetic iron oxide nanoparticles have raised much interest during the recent years due to their novel properties (superparamagnetism, high saturation field, blocking temperature, etc.) and potential applications in organic synthesis, biotechnology and finally in medicine. The medicinal applications include: controlled drug delivery systems (DDS), magnetic resonance imaging (MRI), magnetic fluid hyperthermia (MFH), macromolecules and pathogens separation, cancer therapy and so on. In this paper we would like to present the newest literature reports concerning usage of MNPs in medicinal diagnostics such as: - magnetic separations of DNA (immobilization, isolation, diagnosis of genetic disorders and detection of exogenous substances in the organisms) - magnetic immobilization of proteins (applications in biotechnology, medicine, and catalysis) - magnetic separations of pathogens (i.e. isolation of bacteria, detection of various pathogens) - magnetic resonance imaging (imaging contrast agents, lymphangiography).

Nanoparticles based stem cell tracking in regenerative medicine

Stem cell therapies offer great potentials in the treatment for a wide range of diseases and conditions. With so many stem cell replacement therapies going through clinical trials currently, there is a great need to understand the mechanisms behind a successful therapy, and one of the critical points of discovering them is to track stem cell migration, proliferation and differentiation in vivo. To be of most use tracking methods should ideally be non-invasive, high resolution and allow tracking in three dimensions. Magnetic resonance imaging (MRI) is one of the ideal methods, but requires a suitable contrast agent to be loaded to the cells to be tracked, and one of the most wide-spread in stem cell tracking is a group of agents known as magnetic nanoparticles. This review will explore the current use of magnetic nanoparticles in developing and performing stem cell therapies, and will investigate their potential limitations and the future directions magnetic nanoparticle tracking is heading in.

Directed self-assembly of nanoparticles for nanomotors

We report, for the first time, the design and fabrication of a nanoparticle-based nanomotor system by directly self-assembling nanoparticles onto functional, nanometer-thin lamellae, such as polymer single crystals. Tens of thousands of judiciously selected nanoparticles (gold, iron oxide, and platinum nanoparticles) with sizes ranging from <5 to a few tens of nanometers have been introduced into a single nanomotor via directed self-assembly. The resulting nanomotor realizes functions such as autonomous movement, remote control, and cargo transportation by utilizing the advantages offered by nanoparticles, such as the small size, surface plasmon resonance, catalytic and magnetic properties. Because of the structural and functional versatility of nanoparticles, the facile fabricating procedure, and the potential for mass production, our strategy shows a key step toward the development of next generation multifunctional nanomotors.

High MRI performance fluorescent mesoporous silica-coated magnetic nanoparticles for tracking neural progenitor cells in an ischemic mouse model

Multifunctional probes with high MRI sensitivity and high efficiency for cell labeling are desirable for MR cell imaging. Herein, we have fabricated fluorescent mesoporous silica-coated superparamagnetic iron oxide nanoparticles (fmSiO4@SPIONs) for neural progenitor cell (C17.2) MR imaging. FmSiO4@SPIONs were discrete and uniform in size, and had a clear core-shell structure. The magnetic core size was about 10 nm and the fluorescent mesoporous silica coating layer was around 20 nm. Compared with fluorescent dense silica-coated SPIONs (fdSiO4@SPIONs) with a similar size, fmSiO4@SPIONs demonstrated higher MR sensitivity and cell labeling efficiency. When implanted into the right hemisphere of stroke mice, contralateral to the ischemic territory, a small amount of labeled cells were able to be tracked migrating to the lesion sites using a clinical MRI scanner (3 T). More impressively, even when administered intravenously, the labeled cells could also be monitored homing to the ischemic area. MRI observations were corroborated by histological studies of the brain tissues. Our study demonstrated that fmSiO4@SPIONs are highly effective for cell imaging and hold great promise for MRI cell tracking in future.

Water dispersible magnetite nanoparticles influence the efficacy of antibiotics against planktonic and biofilm embedded Enterococcus faecalis cells

The objective of this study was to investigate the potential of magnetic nanoparticles to potentiate, but also to accomplish a sustained and controlled drug release and subsequently improve the efficacy of antibiotics against Enterococcus faecalis, one of the most resistant opportunistic pathogens, that poses a threat to chronically infected or immunocompromised patients and is difficult to eradicate from medical devices. To our knowledge, this is the first study trying to investigate the ability of magnetite nanoparticles to improve the anti-bacterial activity of the current antibiotics against planktonic and biofilm growing E. faecalis. Our results are suggesting that the magnetite nanoparticles may be considered an effective aminoglycoside antibiotics carrier, but a complete understanding of the way in which they selectively interact with different antibiotics and with the bacterial cell is needed, in order to obtain improved strategies for elimination of E. faecalis biofilms on biomedical devices or human tissues.

Cell transplantation for spinal cord injury: a systematic review

Cell transplantation, as a therapeutic intervention for spinal cord injury (SCI), has been extensively studied by researchers in recent years. A number of different kinds of stem cells, neural progenitors, and glial cells have been tested in basic research, and most have been excluded from clinical studies because of a variety of reasons, including safety and efficacy. The signaling pathways, protein interactions, cellular behavior, and the differentiated fates of experimental cells have been studied in vitro in detail. Furthermore, the survival, proliferation, differentiation, and effects on promoting functional recovery of transplanted cells have also been examined in different animal SCI models. However, despite significant progress, a "bench to bedside" gap still exists. In this paper, we comprehensively cover publications in the field from the last years. The most commonly utilized cell lineages were covered in this paper and specific areas covered include survival of grafted cells, axonal regeneration and remyelination, sensory and motor functional recovery, and electrophysiological improvements. Finally we also review the literature on the in vivo tracking techniques for transplanted cells.

Personalized nanomedicine advancements for stem cell tracking

Recent technological developments in biomedicine have facilitated the generation of data on the anatomical, physiological and molecular level for individual patients and thus introduces opportunity for therapy to be personalized in an unprecedented fashion. Generation of patient-specific stem cells exemplifies the efforts toward this new approach. Cell-based therapy is a highly promising treatment paradigm; however, due to the lack of consistent and unbiased data about the fate of stem cells in vivo, interpretation of therapeutic effects remains challenging hampering the progress in this field. The advent of nanotechnology with a wide palette of inorganic and organic nanostructures has expanded the arsenal of methods for tracking transplanted stem cells. The diversity of nanomaterials has revolutionized personalized nanomedicine and enables individualized tailoring of stem cell labeling materials for the specific needs of each patient. The successful implementation of stem cell tracking will likely be a significant driving force that will contribute to the further development of nanotheranostics. The purpose of this review is to emphasize the role of cell tracking using currently available nanoparticles.

A novel structural motif for free CoPt nanoalloys

The growth of small free platinum-cobalt nanoclusters has been modelled through the one-by-one atom deposition technique based on classical Molecular Dynamics. A novel structural motif, reminiscent of two stacked poly-icosahedral pancakes, has been found in close competition with a Marks-decahedron and a face-centred-cubic geometry at around 75 atoms for a cobalt-rich stoichiometry. The results have been confirmed at the density-functional level, which reveals an unexpected stability of this new morphology over a wide range of chemical compositions. Magnetic properties have been also discussed.

Novel frontiers in ultra-structural and molecular MRI of the brain

PURPOSE OF REVIEW

Recent developments in the MRI of the brain continue to expand its use in basic and clinical neuroscience. This review highlights some areas of recent progress.

RECENT FINDINGS

Higher magnetic field strengths and improved signal detectors have allowed improved visualization of the various properties of the brain, facilitating the anatomical definition of function-specific areas and their connections. For example, by sensitizing the MRI signal to the magnetic susceptibility of tissue, it is starting to become possible to reveal the laminar structure of the cortex and identify millimeter-scale fiber bundles. Using exogenous contrast agents, and innovative ways to manipulate contrast, it is becoming possible to highlight specific fiber tracts and cell populations. These techniques are bringing us closer to understanding the evolutionary blueprint of the brain, improving the detection and characterization of disease, and help to guide treatment.

SUMMARY

Recent MRI techniques are leading to more detailed and more specific contrast in the study of the brain.

A shift from cell cultures to creatures: in vivo imaging of small animals in experimental regenerative medicine

Although the use of small animals for in vivo experimentation has been widespread, only recently has there been easy availability of techniques that allow noninvasive in vivo imaging of small animals. Because these techniques allow the same individual subject to be followed longitudinally throughout the duration of an experiment, their use is rapidly changing the way small animals are employed in the laboratory. In this review, we focus on six imaging modalities that are increasingly employed for small animal in vivo imaging: optical imaging (OI), magnetic resonance imaging (MRI), computed tomography (CT), single-photon emission tomography (SPECT), ultrasound (US), and positron-emission tomography (PET). Each modality allows for the noninvasive tracking of cells and cell products in vivo. In addition, multimodality imaging, combining two or more of these techniques, has also been increasingly employed to overcome the limitations of each independent technique. After reviewing these available imaging modalities, we detail their experimental application, exemplified by the emerging field of regenerative medicine, referring to publications whose conclusions would otherwise be difficult to support without the availability of in vivo imaging.