Detection of amyloid plaques targeted by bifunctional USPIO in Alzheimer's disease transgenic mice using magnetic resonance microimaging

Nanotechnology in the diagnostic and therapy for Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder primarily characterized by β-amyloid plaque, intraneuronal tangles, significant neuronal loss and cognitive deficit. Treatment in the early stages of the disease is crucial for preventing or perhaps reversing the neurodegeneration in the AD cases. However, none of the current diagnostic procedures are capable of early diagnosis of AD. Further, the available treatments merely provide symptomatic alleviation in AD and do not address the underlying illness. Therefore, there is no permanent cure for AD currently. Better therapeutic outcomes need the optimum drug concentration in the central nervous system (CNS) by traversing blood-brain-barrier (BBB). Nanotechnology offers enormous promise to transform the treatment and diagnostics of neurodegenerative diseases. Nanotechnology based diagnostic tools, drug delivery systems and theragnostic are capable of highly sensitive molecular detection, effective drug targeting and their combination. Significant work has been done in this area over the last decade and prospective results have been obtained in AD therapy. This review explores the various applications of nanotechnology in addressing the varied facets of AD, ranging from early detection to therapeutic interventions. This review also looks at how nanotechnology can help with the development of disease-modifying medicines, such as the delivery of anti-amyloid, anti-tau, cholinesterase inhibitors, antioxidants and hormonal drugs. In conclusion, this paper discusses the role of nanotechnology in the early detection of AD, effective drug targeting to the CNS and theragnostic applications in the management of AD.

Evaluation of Dimercaptosuccinic Acid-Coated Iron Nanoparticles Immunotargeted to Amyloid Beta as MRI Contrast Agents for the Diagnosis of Alzheimer's Disease

Nanoparticle-based magnetic contrast agents have opened the potential for magnetic resonance imaging (MRI) to be used for early non-invasive diagnosis of Alzheimer's disease (AD). Accumulation of amyloid pathology in the brain has shown association with cognitive decline and tauopathy; hence, it is an effective biomarker for the early detection of AD. The aim of this study was to develop a biocompatible magnetic nanoparticle targeted to amyloid beta (Aβ) plaques to increase the sensitivity of T2-weighted MRI for imaging of amyloid pathology in AD. We presented novel iron core-iron oxide nanoparticles stabilized with a dimercaptosuccinic acid coating and functionalized with an anti-Aβ antibody. Nanoparticle biocompatibility and cellular internalization were evaluated in vitro in U-251 glioblastoma cells using cellular assays, proteomics, and transmission electron microscopy. Iron nanoparticles demonstrated no significant in vitro cytotoxicity, and electron microscopy results showed their movement through the endocytic cycle within the cell over a 24 h period. In addition, immunostaining and bio-layer interferometry confirmed the targeted nanoparticle's binding affinity to amyloid species. The iron nanoparticles demonstrated favourable MRI contrast enhancement; however, the addition of the antibody resulted in a reduction in the relaxivity of the particles. The present work shows promising preliminary results in the development of a targeted non-invasive method of early AD diagnosis using contrast-enhanced MRI.

A Promising Approach: Magnetic Nanosystems for Alzheimer's Disease Theranostics

Among central nervous system (CNS) disorders, Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder and a major cause of dementia worldwide. The yet unclear etiology of AD and the high impenetrability of the blood-brain barrier (BBB) limit most therapeutic compounds from reaching the brain. Although many efforts have been made to effectively deliver drugs to the CNS, both invasive and noninvasive strategies employed often come with associated side effects. Nanotechnology-based approaches such as nanoparticles (NPs), which can act as multifunctional platforms in a single system, emerged as a potential solution for current AD theranostics. Among these, magnetic nanoparticles (MNPs) are an appealing strategy since they can act as contrast agents for magnetic resonance imaging (MRI) and as drug delivery systems. The nanocarrier functionalization with specific moieties, such as peptides, proteins, and antibodies, influences the particles' interaction with brain endothelial cell constituents, facilitating transport across the BBB and possibly increasing brain penetration. In this review, we introduce MNP-based systems, combining surface modifications with the particles' physical properties for molecular imaging, as a novel neuro-targeted strategy for AD theranostics. The main goal is to highlight the potential of multifunctional MNPs and their advances as a dual nanotechnological diagnosis and treatment platform for neurodegenerative disorders.

Peptide-metal nanohybrids (PMN): Promising entities for combating neurological maladies

Nanotherapeutics are gaining traction in the modern scenario because of their unique and distinct properties which separate them from macro materials. Among the nanoparticles, metal NPs (MNPs) have gained importance due to their distinct physicochemical and biological characteristics. Peptides also exhibit several important functions in humans. Different peptides have received approval as pharmaceuticals, and clinical trials have been commenced for several peptides. Peptides are also used as targeting ligands. Considering all the advantages offered by these two entities, the conjugation of MNPs with peptides has emerged as a potential strategy for achieving successful targeting, diagnosis, and therapy of various neurological pathologies.

Molecular Design of Magnetic Resonance Imaging Agents Binding to Amyloid Deposits

The ability to detect and monitor amyloid deposition in the brain using non-invasive imaging techniques provides valuable insights into the early diagnosis and progression of Alzheimer's disease and helps to evaluate the efficacy of potential treatments. Magnetic resonance imaging (MRI) is a widely available technique offering high-spatial-resolution imaging. It can be used to visualize amyloid deposits with the help of amyloid-binding diagnostic agents injected into the body. In recent years, a number of amyloid-targeted MRI probes have been developed, but none of them has entered clinical practice. We review the advances in the field and deduce the requirements for the molecular structure and properties of a diagnostic probe candidate. These requirements make up the base for the rational design of MRI-active small molecules targeting amyloid deposits. Particular attention is paid to the novel cryo-EM structures of the fibril aggregates and their complexes, with known binders offering the possibility to use computational structure-based design methods. With continued research and development, MRI probes may revolutionize the diagnosis and treatment of neurodegenerative diseases, ultimately improving the lives of millions of people worldwide.

Magnetic Iron Oxide Nanoparticles for Brain Imaging and Drug Delivery

Central nervous system (CNS) disorders affect as many as 1.5 billion people globally. The limited delivery of most imaging and therapeutic agents into the brain is a major challenge for treatment of CNS disorders. With the advent of nanotechnologies, controlled delivery of drugs with nanoparticles holds great promise in CNS disorders for overcoming the blood-brain barrier (BBB) and improving delivery efficacy. In recent years, magnetic iron oxide nanoparticles (MIONPs) have stood out as a promising theranostic nanoplatform for brain imaging and drug delivery as they possess unique physical properties and biodegradable characteristics. In this review, we summarize the recent advances in MIONP-based platforms as imaging and drug delivery agents for brain diseases. We firstly introduce the methods of synthesis and surface functionalization of MIONPs with emphasis on the inclusion of biocompatible polymers that allow for the addition of tailored physicochemical properties. We then discuss the recent advances in in vivo imaging and drug delivery applications using MIONPs. Finally, we present a perspective on the remaining challenges and possible future directions for MIONP-based brain delivery systems.

In vivo targeting and multimodal imaging of cerebral amyloid-β aggregates using hybrid GdF3 nanoparticles

Aim: To propose a new multimodal imaging agent targeting amyloid-β (Aβ) plaques in Alzheimer's disease. Materials & methods: A new generation of hybrid contrast agents, based on gadolinium fluoride nanoparticles grafted with a pentameric luminescent-conjugated polythiophene, was designed, extensively characterized and evaluated in animal models of Alzheimer's disease through MRI, two-photon microscopy and synchrotron x-ray phase-contrast imaging. Results & conclusion: Two different grafting densities of luminescent-conjugated polythiophene were achieved while preserving colloidal stability and fluorescent properties, and without affecting biodistribution. In vivo brain uptake was dependent on the blood-brain barrier status. Nevertheless, multimodal imaging showed successful Aβ targeting in both transgenic mice and Aβ fibril-injected rats.

Nanomedicine-based immunotherapy for Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease caused by the deposition of amyloid β (Aβ) fibrils forming extracellular plaques and the development of neurofibrillary tangles (NFT) of intracellular hyperphosphorylated tau protein. Currently, the AD treatments focus on improving cognitive and behavioral symptoms and have limited success. It is imperative to develop novel treatment approaches that can control/inhibit AD progression, especially in the elderly population. Immunotherapy provides a promising and safe treatment option for AD by boosting the patient's immune system. The minimum immune surveillance in the immune-privileged brain, however, makes immunotherapy for AD a challenging endeavor. Therefore, the success of AD immunotherapy depends mainly on the strategy by which therapeutics is delivered to the brain rather than its efficacy. The blood-brain barrier (BBB) is a major obstacle to therapeutic delivery into the brain microenvironment. Various nano-formulations have been exploited to improve the efficacy of AD immunotherapy. In this review, the applications of different types of nano-formulations in augmenting AD immunotherapy have been discussed.

CAQK, a peptide associating with extracellular matrix components targets sites of demyelinating injuries

The destruction of the myelin sheath that encircles axons leads to impairments of nerve conduction and neuronal dysfunctions. A major demyelinating disorder is multiple sclerosis (MS), a progressively disabling disease in which immune cells attack the myelin. To date, there are no therapies to target selectively myelin lesions, repair the myelin or stop MS progression. Small peptides recognizing epitopes selectively exposed at sites of injury show promise for targeting therapeutics in various pathologies. Here we show the selective homing of the four amino acid peptide, cysteine-alanine-lysine glutamine (CAQK), to sites of demyelinating injuries in three different mouse models. Homing was assessed by administering fluorescein amine (FAM)-labeled peptides into the bloodstream of mice and analyzing sites of demyelination in comparison with healthy brain or spinal cord tissue. FAM-CAQK selectively targeted demyelinating areas in all three models and was absent from healthy tissue. At lesion sites, the peptide was primarily associated with the fibrous extracellular matrix (ECM) deposited in interstitial spaces proximal to reactive astrocytes. Association of FAM-CAQK was detected with tenascin-C although tenascin depositions made up only a minor portion of the examined lesion sites. In mice on a 6-week cuprizone diet, FAM-CAQK peptide crossed the nearly intact blood-brain barrier and homed to demyelinating fiber tracts. These results demonstrate the selective targeting of CAQK to demyelinating injuries under multiple conditions and confirm the previously reported association with the ECM. This work sets the stage for further developing CAQK peptide targeting for diagnostic and therapeutic applications aimed at localized myelin repair.

Nanomedicines in the Management of Alzheimer’s Disease: Current View and Future Prospects

Alzheimer’s disease (AD) is a kind of dementia that creates serious challenges for sufferers’ memory, thinking, and behavior. It commonly targeting the aging population and decay the brain cells, despite attempts have been performed to enhance AD diagnostic and therapeutic techniques. Hence, AD remains incurable owing to its complex and multifactorial consequences and still there is lack of appropriate diagnostics/therapeutics option for this severe brain disorder. Therefore, nanotechnology is currently bringing new tools and insights to improve the previous knowledge of AD and ultimately may provide a novel treatment option and a ray of hope to AD patients. Here in this review, we highlighted the nanotechnologies-based findings for AD, in both diagnostic and therapeutic aspects and explained how advances in the field of nanotechnology/nanomedicine could enhance patient prognosis and quality of life. It is highly expected these emerging technologies could bring a research-based revolution in the field of neurodegenerative disorders and may assist their clinical experiments and develop an efficacious drug for AD also. The main aim of review is to showcase readers the recent advances in nanotechnology-based approaches for treatment and diagnosing of AD.

Advances of functional nanomaterials for magnetic resonance imaging and biomedical engineering applications

Functional nanomaterials have been widely used in biomedical fields due to their good biocompatibility, excellent physicochemical properties, easy surface modification, and easy regulation of size and morphology. Functional nanomaterials for magnetic resonance imaging (MRI) can target specific sites in vivo and more easily detect disease-related specific biomarkers at the molecular and cellular levels than traditional contrast agents, achieving a broad application prospect in MRI. This review focuses on the basic principles of MRI, the classification, synthesis and surface modification methods of contrast agents, and their clinical applications to provide guidance for designing novel contrast agents and optimizing the contrast effect. Furthermore, the latest biomedical advances of functional nanomaterials in medical diagnosis and disease detection, disease treatment, the combination of diagnosis and treatment (theranostics), multi-model imaging and nanozyme are also summarized and discussed. Finally, the bright application prospects of functional nanomaterials in biomedicine are emphasized and the urgent need to achieve significant breakthroughs in the industrial transformation and the clinical translation is proposed. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Diagnostic Tools > Diagnostic Nanodevices Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Therapeutic nanotechnologies for Alzheimer's disease: a critical analysis of recent trends and findings

Alzheimer's Disease (AD) is an irreversible neurodegenerative disease for which no disease modifying therapies are presently available. Besides the identification of pathological targets, AD presents numerous clinical and pharmacological challenges such as efficient active delivery to the central nervous system, cell targeting, and long-term dosing. Nanoparticles have been explored to overcome some of these challenges as drug delivery vehicles or drugs themselves. However, early promises have failed to materialize as no nanotechnology-based product has been able to reach the market and very few have moved past preclinical stages. In this review, we perform a critical analysis of the past decade's research on nanomedicine-based therapies for AD at the preclinical and clinical stages. The main obstacles to nanotechnology products and the most promising approaches were also identified, including renewed promise with gene editing, gene modulation, and vaccines.

Recent advancements of nanoparticles application in cancer and neurodegenerative disorders: At a glance

Nanoscale engineering is one of the innovative approaches to heal multitudes of ailments, such as varieties of malignancies, neurological problems, and infectious illnesses. Therapeutics for neurodegenerative diseases (NDs) may be modified in aspect because of their ability to stimulate physiological response while limiting negative consequences by interfacing and activating possible targets. Nanomaterials have been extensively studied and employed for cancerous therapeutic strategies since nanomaterials potentially play a significant role in medical transportation. When compared to conventional drug delivery, nanocarriers drug delivery offers various benefits, such as excellent reliability, bioactivity, improved penetration and retention impact, as well as precise targeting and administering. Upregulation of drug efflux transporters, dysfunctional apoptotic mechanisms, and a hypoxic atmosphere are all elements that lead to cancer treatment sensitivity in humans. It has been possible to target these pathways using nanoparticles and increase the effectiveness of multidrug resistance treatments. As innovative strategies of tumor chemoresistance are uncovered, nanomaterials are being developed to target specific pathways of tumor resilience. Scientists have recently begun investigating the function of nanoparticles in immunotherapy, a field that is becoming increasingly useful in the care of malignancies. Nanoscale therapeutics have been explored in this scientific literature and represent the most current approaches to neurodegenerative illnesses and cancer therapy. In addition, current findings and various biomedical nanomaterials' future promise for tissue regeneration, prospective medication design, and the synthesis of novel delivery approaches have been emphasized.

Magnetic Resonance Imaging in Animal Models of Alzheimer's Disease Amyloidosis

Amyloid-beta (Aβ) plays an important role in the pathogenesis of Alzheimer's disease. Aberrant Aβ accumulation induces neuroinflammation, cerebrovascular alterations, and synaptic deficits, leading to cognitive impairment. Animal models recapitulating the Aβ pathology, such as transgenic, knock-in mouse and rat models, have facilitated the understanding of disease mechanisms and the development of therapeutics targeting Aβ. There is a rapid advance in high-field MRI in small animals. Versatile high-field magnetic resonance imaging (MRI) sequences, such as diffusion tensor imaging, arterial spin labeling, resting-state functional MRI, anatomical MRI, and MR spectroscopy, as well as contrast agents, have been developed for preclinical imaging in animal models. These tools have enabled high-resolution in vivo structural, functional, and molecular readouts with a whole-brain field of view. MRI has been used to visualize non-invasively the Aβ deposits, synaptic deficits, regional brain atrophy, impairment in white matter integrity, functional connectivity, and cerebrovascular and glymphatic system in animal models of Alzheimer's disease amyloidosis. Many of the readouts are translational toward clinical MRI applications in patients with Alzheimer's disease. In this review, we summarize the recent advances in MRI for visualizing the pathophysiology in amyloidosis animal models. We discuss the outstanding challenges in brain imaging using MRI in small animals and propose future outlook in visualizing Aβ-related alterations in the brains of animal models.

Microenvironment-tailored nanoassemblies for the diagnosis and therapy of neurodegenerative diseases

Neurodegenerative disorder is an illness involving neural dysfunction/death attributed to complex pathological processes, which eventually lead to the mortality of the host. It is generally recognized through features such as mitochondrial dysfunction, protein aggregation, oxidative stress, metal ions dyshomeostasis, membrane potential change, neuroinflammation and neurotransmitter impairment. The aforementioned neuronal dysregulations result in the formation of a complex neurodegenerative microenvironment (NME), and may interact with each other, hindering the performance of therapeutics for neurodegenerative disease (ND). Recently, smart nanoassemblies prepared from functional nanoparticles, which possess the ability to interfere with different NME factors, have shown great promise to enhance the diagnostic and therapeutic efficacy of NDs. Herein, this review highlights the recent advances of stimuli-responsive nanoassemblies that can effectively combat the NME for the management of ND. The first section outlined the NME properties and their interrelations that are exploitable for nanoscale targeting. The discussion is then extended to the controlled assembly of functional nanoparticles for the construction of stimuli-responsive nanoassemblies. Further, the applications of stimuli-responsive nanoassemblies for the enhanced diagnosis and therapy of ND are introduced. Finally, perspectives on the future development of NME-tailored nanomedicines are given.

Magnetic Nanoparticles as In Vivo Tracers for Alzheimer’s Disease

Drug formulations and suitable methods for their detection play a very crucial role in the development of therapeutics towards degenerative neurological diseases. For diseases such as Alzheimer’s disease, magnetic resonance imaging (MRI) is a non-invasive clinical technique suitable for early diagnosis. In this review, we will discuss the different experimental conditions which can push MRI as the technique of choice and the gold standard for early diagnosis of Alzheimer’s disease. Here, we describe and compare various techniques for administration of nanoparticles targeted to the brain and suitable formulations of nanoparticles for use as magnetically active therapeutic probes in drug delivery targeting the brain. We explore different physiological pathways involved in the transport of such nanoparticles for successful entry in the brain. In our lab, we have used different formulations of iron oxide nanoparticles (IONPs) and protein nanocages as contrast agents in anatomical MRI of an Alzheimer’s disease (AD) brain. We compare these coatings and their benefits to provide the best contrast in addition to biocompatibility properties to be used as sustainable drug-release systems. In the later sections, the contrast enhancement techniques in MRI studies are discussed. Examples of contrast-enhanced imaging using advanced pulse sequences are discussed with the main focus on important studies in the field of neurological diseases. In addition, T1 contrast agents such as gadolinium chelates are compared with the T2 contrast agents mainly made of superparamagnetic inorganic metal nanoparticles.

Nanoparticles as contrast agents for the diagnosis of Alzheimer’s disease: a systematic review

Nanoparticle (NP)-based magnetic contrast agents have opened the potential for MRI to be used for early diagnosis of Alzheimer’s disease (AD). This article aims to review the current progress of research in this field. A comprehensive literature search was performed based on PubMed, Medline, EMBASE, PsychINFO and Scopus databases using the following terms: ‘Alzheimer’s disease’ AND ‘nanoparticles’ AND ‘Magnetic Resonance Imaging.’ 33 studies were included that described the development and utility of various NPs for AD imaging, including their coating, functionalization, MRI relaxivity, toxicity and bioavailability. NPs show immense promise for neuroimaging, due to superior relaxivity and biocompatibility compared with currently available imaging agents. Consistent reporting is imperative for further progress in this field.

Application of Iron Oxide Nanoparticles in the Diagnosis and Treatment of Neurodegenerative Diseases With Emphasis on Alzheimer's Disease

Neurodegenerative diseases are characterized by chronic progressive degeneration of the structure and function of the nervous system, which brings an enormous burden on patients, their families, and society. It is difficult to make early diagnosis, resulting from the insidious onset and progressive development of neurodegenerative diseases. The drugs on the market cannot cross the blood-brain barrier (BBB) effectively, which leads to unfavorable prognosis and less effective treatments. Therefore, there is an urgent demand to develop a novel detection method and therapeutic strategies. Recently, nanomedicine has aroused considerable attention for diagnosis and therapy of central nervous system (CNS) diseases. Nanoparticles integrate targeting, imaging, and therapy in one system and facilitate the entry of drug molecules across the blood-brain barrier, offering new hope to patients. In this review, we summarize the application of iron oxide nanoparticles (IONPs) in the diagnosis and treatment of neurodegenerative disease, including Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). We focus on IONPs as magnetic resonance imaging (MRI) contrast agents (CAs) and drug carriers in AD. What most neurodegenerative diseases have in common is that hall marker lesions are represented by protein aggregates (Soto and Pritzkow, 2018). These diseases are of unknown etiology and unfavorable prognosis, and the treatments toward them are less effective (Soto and Pritzkow, 2018). Such diseases usually develop in aged people, and early clinical manifestations are atypical, resulting in difficulty in early diagnosis. Recently, nanomedicine has aroused considerable attention for therapy and diagnosis of CNS diseases because it integrates targeting, imaging, and therapy in one system (Gupta et al., 2019). In this review article, we first introduce the neurodegenerative diseases and commonly used MRI CAs. Then we review the application of IONPs in the diagnosis and treatment of neurodegenerative diseases with the purpose of assisting early theranostics (therapy and diagnosis).

Alzheimer's disease: review of current nanotechnological therapeutic strategies

Introduction: Alzheimer's Disease (AD) is a progressive neurodegenerative pathology characterized by the presence of neuritic plaques and neurofibrillary tangles. The most important markers in AD pathology include excessive accumulation of amyloid beta (Aβ₄₂) and phosphorylated tau (P-tau) proteins. One of the possible therapeutic strategies entails the elimination of such deposits by inhibiting Aβ aggregation. For years, one of the major problems in the treatment of AD has been the limited ability to deliver drugs to the brain for reasons related to poor solubility, low bioavailability, and the impact of the blood-brain barrier (BBB).Areas covered: In recent years, the authors have observed an increasing scientific interest in nanotechnological solutions as the factors potentially capable of facilitating the treatment of neurodegenerative diseases. The authors discuss recent reports regarding the use of nanotechnology in the therapy and treatment of AD.Expert opinion: The current advances in nanotechnology promise a chance to overcome the obstacles posed by said limitations. The size and diversity of nanoparticles in terms of both composition and shape create new possibilities for a variety of therapeutic applications, also in the context of the treatment and diagnostics of neurodegenerative diseases, for instance in combination with magnetic resonance imaging.

Metal-based imaging agents: progress towards interrogating neurodegenerative disease

Transition metals and lanthanide ions display unique properties that enable the development of non-invasive diagnostic tools for imaging. In this review, we highlight various metal-based imaging strategies used to interrogate neurodegeneration.

Synthesis, Principles, and Properties of Magnetite Nanoparticles for In Vivo Imaging Applications-A Review

The current nanotechnology era is marked by the emergence of various magnetic inorganic nanometer-sized colloidal particles. These have been extensively applied and hold an immense potential in biomedical applications including, for example, cancer therapy, drug nanocarriers (NCs), or in targeted delivery systems and diagnosis involving two guided-nanoparticles (NPs) as nanoprobes and contrast agents. Considerable efforts have been devoted to designing iron oxide NPs (IONPs) due to their superparamagnetic (SPM) behavior (SPM IONPs or SPIONs) and their large surface-to-volume area allowing more biocompatibility, stealth, and easy bonding to natural biomolecules thanks to grafted ligands, selective-site moieties, and/or organic and inorganic corona shells. Such nanomagnets with adjustable architecture have been the topic of significant progresses since modular designs enable SPIONs to carry out several functions simultaneously such as local drug delivery with real-time monitoring and imaging of the targeted area. Syntheses of SPIONs and adjustments of their physical and chemical properties have been achieved and paved novel routes for a safe use of those tailored magnetic ferrous nanomaterials. Herein we will emphasis a basic notion about NPs magnetism in order to have a better understanding of SPION assets for biomedical applications, then we mainly focus on magnetite iron oxide owing to its outstanding magnetic properties. The general methods of preparation and typical characteristics of magnetite are reviewed, as well as the major biomedical applications of magnetite.

Synergistic effect of STAT3‑targeted small interfering RNA and AZD0530 against glioblastoma in vitro and in vivo

The aim of this study was to explore the synergistic effect of signal transducer and activator of transcription 3 (STAT3)-targeted small interfering (si)RNA and AZD0530 against glioblastoma in vitro and in vivo. Glioblastoma cell lines U87 and U251 were divided into four groups and treated with control, LV-STAT3 siRNA, AZD0530, and combined LV-STAT3 siRNA with AZD0530, respectively. The proliferation and apoptotic capacity of glioblastoma cells was assessed by Cell Counting Kit-8 and double staining flow cytometry assays, respectively. Additionally, the potential effect of LV-STAT3 siRNA and AZD0530 on glioblastoma was evaluated in vivo. Images were captured of the tumor formation in mice every week. Following three weeks of treatment, NMR scan and immunohistochemistry were performed. The treatment of combined LV-STAT3 siRNA and AZD0530 was more effective in inhibiting proliferation and inducing apoptosisof glioblastoma cells in comparison with the treatment of either LV-STAT3 siRNA or AZD0530 alone. Although LV-STAT3 siRNA or AZD0530 treatment alone suppressed tumor growth in mice, the combined treatment had a more significant effect than the treatment of LV-STAT3 siRNA or AZD0530 alone. According to the results of both in vitro and in vivo assays, a combined therapy of LV-STAT3 siRNA with AZD0530 could enhance therapeutic effects on glioblastoma, supporting the idea that the combination of LV-STAT3 siRNA and AZD0530 could serve as a novel and effective strategy to combat glioblastoma.

Enabling biodegradable functional biomaterials for the management of neurological disorders

An increasing number of patients are being diagnosed with neurological diseases, but are rarely cured because of the lack of curative therapeutic approaches. This situation creates an urgent clinical need to develop effective diagnosis and treatment strategies for repair and regeneration of injured or diseased neural tissues. In this regard, biodegradable functional biomaterials provide promising solutions to meet this demand owing to their unique responsiveness to external stimulation fields, which enable neuro-imaging, neuro-sensing, specific targeting, hyperthermia treatment, controlled drug delivery, and nerve regeneration. This review discusses recent progress in the research and development of biodegradable functional biomaterials including electroactive biomaterials, magnetic materials and photoactive biomaterials for the management of neurological disorders with emphasis on their applications in bioimaging (photoacoustic imaging, MRI and fluorescence imaging), biosensing (electrochemical sensing, magnetic sensing and opical sensing), and therapy strategies (drug delivery, hyperthermia treatment, and tissue engineering). It is expected that this review will provide an insightful discussion on the roles of biodegradable functional biomaterials in the diagnosis and treatment of neurological diseases, and lead to innovations for the design and development of the next generation biodegradable functional biomaterials.

Protein-Engineered Nanoscale Micelles for Dynamic 19F Magnetic Resonance and Therapeutic Drug Delivery

Engineered proteins provide an interesting template for designing fluorine-19 (19F) magnetic resonance imaging (MRI) contrast agents, yet progress has been hindered by the unpredictable relaxation properties of fluorine. Herein, we present the biosynthesis of a protein block copolymer, termed "fluorinated thermoresponsive assembled protein" (F-TRAP), which assembles into a monodisperse nanoscale micelle with interesting 19F NMR properties and the ability to encapsulate and release small therapeutic molecules, imparting potential as a diagnostic and therapeutic (theranostic) agent. The assembly of the F-TRAP micelle, composed of a coiled-coil pentamer corona and a hydrophobic, thermoresponsive elastin-like polypeptide core, results in a drastic depression in spin-spin relaxation ( T2) times and unaffected spin-lattice relaxation ( T1) times. The nearly unchanging T1 relaxation rates and linearly dependent T2 relaxation rates have allowed for detection via zero echo time 19F MRI, and the in vivo MR potential has been preliminarily explored using 19F magnetic resonance spectroscopy (MRS). This fluorinated micelle has also demonstrated the ability to encapsulate the small-molecule chemotherapeutic doxorubicin and release its cargo in a thermoresponsive manner owing to its inherent stimuli-responsive properties, presenting an interesting avenue for the development of thermoresponsive 19F MRI/MRS-traceable theranostic agents.

A Novel Contrast Agent Based on Magnetic Nanoparticles for Cholesterol Detection as Alzheimer's Disease Biomarker

BACKGROUND

Considering the high incidence of Alzheimer's disease among the world population over the years, and the costs that the disease poses in sanitary and social terms to countries, it is necessary to develop non-invasive diagnostic tests that allow to detect early biomarkers of the disease. Within the early diagnosis methods, the development of contrast agents for magnetic resonance imaging becomes especially useful. Accumulating evidence suggests that cholesterol may play a role in the pathogenesis of Alzheimer's disease since abnormal deposits of cholesterol surrounding senile plaques have been described in animal transgenic models and patients with Alzheimer's disease. In vivo experiments have also shown that diet-induced hypercholesterolemia enhances intraneuronal accumulation of β-amyloid protein accompanied by microgliosis and accelerates β-amyloid deposition in brains.

PRESENTATION OF THE HYPOTHESIS

In the present study, we propose for the first time the synthesis of a new nanoconjugate composed of magnetic nanoparticles bound to an anti-cholesterol antibody, to detect the abnormal deposits of cholesterol observed in senile plaques in Alzheimer's disease by magnetic resonance imaging. The nanoplatform could also reveal the decrease of cholesterol observed in neuronal plasmatic membranes associated with this pathology.

TESTING THE HYPOTHESIS

Experimental design to test the hypothesis will be done first in vitro and then in ex vivo and in vivo studies in a second stage.

IMPLICATIONS OF THE HYPOTHESIS

The designed nanoplatform could therefore detect cholesterol deposits at the cerebral level. The detection of this biomarker in areas coinciding with senile plaque accumulations could provide early information on the onset and progression of Alzheimer's disease.

Chemistry of MRI Contrast Agents: Current Challenges and New Frontiers

Tens of millions of contrast-enhanced magnetic resonance imaging (MRI) exams are performed annually around the world. The contrast agents, which improve diagnostic accuracy, are almost exclusively small, hydrophilic gadolinium(III) based chelates. In recent years concerns have arisen surrounding the long-term safety of these compounds, and this has spurred research into alternatives. There has also been a push to develop new molecularly targeted contrast agents or agents that can sense pathological changes in the local environment. This comprehensive review describes the state of the art of clinically approved contrast agents, their mechanism of action, and factors influencing their safety. From there we describe different mechanisms of generating MR image contrast such as relaxation, chemical exchange saturation transfer, and direct detection and the types of molecules that are effective for these purposes. Next we describe efforts to make safer contrast agents either by increasing relaxivity, increasing resistance to metal ion release, or by moving to gadolinium(III)-free alternatives. Finally we survey approaches to make contrast agents more specific for pathology either by direct biochemical targeting or by the design of responsive or activatable contrast agents.

Nanocarriers as a powerful vehicle to overcome blood-brain barrier in treating neurodegenerative diseases: Focus on recent advances

Neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Huntington disease and amyotrophic lateral sclerosis throw a heavy burden on families and society. Related scientific researches make tardy progress. One reason is that the known pathogeny is just the tip of the iceberg. Another reason is that various physiological barriers, especially blood-brain barrier (BBB), hamper effective therapeutic substances from reaching site of action. Drugs in clinical treatment of neurodegenerative diseases are basically administered orally. And generally speaking, the brain targeting efficiency is pretty low. Nano-delivery technology brings hope for neurodegenerative diseases. The use of nanocarriers encapsulating molecules such as peptides and genomic medicine may enhance drug transport through the BBB in neurodegenerative disease and target relevant regions in the brain for regenerative processes. In this review, we discuss BBB composition and applications of nanocarriers -liposomes, nanoparticles, nanomicelles and new emerging exosomes in neurodegenerative diseases. Furthermore, the disadvantages and the potential neurotoxicity of nanocarriers according pharmacokinetics theory are also discussed.

Magnetic Nanoparticles Applications for Amyloidosis Study and Detection: A Review

Magnetic nanoparticles (MNPs) have great potential in biomedical and clinical applications because of their many unique properties. This contribution provides an overview of the MNPs mainly used in the field of amyloid diseases. The first part discusses their use in understanding the amyloid mechanisms of fibrillation, with emphasis on their ability to control aggregation of amyloidogenic proteins. The second part deals with the functionalization by various moieties of numerous MNPs’ surfaces (molecules, peptides, antibody fragments, or whole antibodies of MNPs) for the detection and the quantification of amyloid aggregates. The last part of this review focuses on the use of MNPs for magnetic-resonance-based amyloid imaging in biomedical fields, with particular attention to the application of gadolinium-based paramagnetic nanoparticles (AGuIX), which have been recently developed. Biocompatible AGuIX nanoparticles show favorable characteristics for in vivo use, such as nanometric and straightforward functionalization. Their properties have enabled their application in MRI. Here, we report that AGuIX nanoparticles grafted with the Pittsburgh compound B can actively target amyloid aggregates in the brain, beyond the blood–brain barrier, and remain the first step in observing amyloid plaques in a mouse model of Alzheimer’s disease.

High-resolution Imaging of Myeloperoxidase Activity Sensors in Human Cerebrovascular Disease

Progress in clinical development of magnetic resonance imaging (MRI) substrate-sensors of enzymatic activity has been slow partly due to the lack of human efficacy data. We report here a strategy that may serve as a shortcut from bench to bedside. We tested ultra high-resolution 7T MRI (µMRI) of human surgical histology sections in a 3-year IRB approved, HIPAA compliant study of surgically clipped brain aneurysms. µMRI was used for assessing the efficacy of MRI substrate-sensors that detect myeloperoxidase activity in inflammation. The efficacy of Gd-5HT-DOTAGA, a novel myeloperoxidase (MPO) imaging agent synthesized by using a highly stable gadolinium (III) chelate was tested both in tissue-like phantoms and in human samples. After treating histology sections with paramagnetic MPO substrate-sensors we observed relaxation time shortening and MPO activity-dependent MR signal enhancement. An increase of normalized MR signal generated by ultra-short echo time MR sequences was corroborated by MPO activity visualization by using a fluorescent MPO substrate. The results of µMRI of MPO activity associated with aneurysmal pathology and immunohistochemistry demonstrated active involvement of neutrophils and neutrophil NETs as a result of pro-inflammatory signalling in the vascular wall and in the perivascular space of brain aneurysms.

Functionalization and Characterization of Magnetic Nanoparticles for the Detection of Ferritin Accumulation in Alzheimer's Disease

Early diagnosis in Alzheimer's disease (AD), prior to the appearance of marked clinical symptoms, is critical to prevent irreversible neuronal damage and neural malfunction that lead to dementia and death. Therefore, there is an urgent need to generate new contrast agents which reveal by a noninvasive method the presence of some of the pathological signs of AD. In the present study, we demonstrate for the first time a new nanoconjugate composed of magnetic nanoparticles bound to an antiferritin antibody, which has been developed based on the existence of iron deposits and high levels of the ferritin protein present in areas with a high accumulation of amyloid plaques (particularly the subiculum in the hippocampal area) in the brain of a transgenic mouse model with five familial AD mutations. Both in vitro and after intravenous injection, functionalized magnetic nanoparticles were able to recognize and bind specifically to the ferritin protein accumulated in the subiculum area of the AD transgenic mice.

Detection of β-Amyloid by Sialic Acid Coated Bovine Serum Albumin Magnetic Nanoparticles in a Mouse Model of Alzheimer's Disease

The accumulation and formation of β-amyloid (Aβ) plaques in the brain are distinctive pathological hallmarks of Alzheimer's disease (AD). Designing nanoparticle (NP) contrast agents capable of binding with Aβ highly selectively can potentially facilitate early detection of AD. However, a significant obstacle is the blood brain barrier (BBB), which can preclude the entrance of NPs into the brain for Aβ binding. In this work, bovine serum albumin (BSA) coated NPs are decorated with sialic acid (NP-BSAx -Sia) to overcome the challenges in Aβ imaging in vivo. The NP-BSAx -Sia is biocompatible with high magnetic relaxivities, suggesting that they are suitable contrast agents for magnetic resonance imaging (MRI). The NP-BSAx -Sia binds with Aβ in a sialic acid dependent manner with high selectivities toward Aβ deposited on brains and cross the BBB in an in vitro model. The abilities of these NPs to detect Aβ in vivo in human AD transgenic mice by MRI are evaluated without the need to coinject mannitol to increase BBB permeability. T2 *-weighted MRI shows that Aβ plaques in mouse brains can be detected as aided by NP-BSAx -Sia, which is confirmed by histological analysis. Thus, NP-BSAx -Sia is a promising new tool for noninvasive in vivo detection of Aβ plaques.

Mouse models of neurodegenerative disease: preclinical imaging and neurovascular component

Neurodegenerative diseases represent great challenges for basic science and clinical medicine because of their prevalence, pathologies, lack of mechanism-based treatments, and impacts on individuals. Translational research might contribute to the study of neurodegenerative diseases. The mouse has become a key model for studying disease mechanisms that might recapitulate in part some aspects of the corresponding human diseases. Neurodegenerative disorders are very complicated and multifactorial. This has to be taken in account when testing drugs. Most of the drugs screening in mice are very difficult to be interpretated and often useless. Mouse models could be condiderated a 'pathway models', rather than as models for the whole complicated construct that makes a human disease. Non-invasive in vivo imaging in mice has gained increasing interest in preclinical research in the last years thanks to the availability of high-resolution single-photon emission computed tomography (SPECT), positron emission tomography (PET), high field Magnetic resonance, Optical Imaging scanners and of highly specific contrast agents. Behavioral test are useful tool to characterize different animal models of neurodegenerative pathology. Furthermore, many authors have observed vascular pathological features associated to the different neurodegenerative disorders. Aim of this review is to focus on the different existing animal models of neurodegenerative disorders, describe behavioral tests and preclinical imaging techniques used for diagnose and describe the vascular pathological features associated to these diseases.

Nanoparticles as contrast agents for brain nuclear magnetic resonance imaging in Alzheimer's disease diagnosis

Nuclear Magnetic Resonance Imaging (MRI) of amyloid plaques is a powerful non-invasive approach for the early and accurate diagnosis of Alzheimer's disease (AD) along with clinical observations of behavioral changes and cognitive impairment. The present article aims at giving a critical and comprehensive review of recent advances in the development of nanoparticle-based contrast agents for brain MRI. Nanoparticles considered for the MRI of AD must comply with a highly stringent set of requirements including low toxicity and the ability to cross the blood-brain-barrier. In addition, to reach an optimal signal-to-noise ratio, they must exhibit a specific ability to target amyloid plaques, which can be achieved by grafting antibodies, peptides or small molecules. Finally, we propose to consider new directions for the future of MRI in the context of Alzheimer's disease, in particular by enhancing the performances of contrast agents and by including therapeutic functionalities following a theranostic strategy.

Contrast-enhanced MR microscopy of amyloid plaques in five mouse models of amyloidosis and in human Alzheimer's disease brains

Gadolinium (Gd)-stained MRI is based on Gd contrast agent (CA) administration into the brain parenchyma. The strong signal increase induced by Gd CA can be converted into resolution enhancement to record microscopic MR images. Moreover, inhomogeneous distribution of the Gd CA in the brain improves the contrast between different tissues and provides new contrasts in MR images. Gd-stained MRI detects amyloid plaques, one of the microscopic lesions of Alzheimer’s disease (AD), in APP_SL/PS1_M146L mice or in primates. Numerous transgenic mice with various plaque typologies have been developed to mimic cerebral amyloidosis and comparison of plaque detection between animal models and humans with new imaging methods is a recurrent concern. Here, we investigated detection of amyloid plaques by Gd-stained MRI in five mouse models of amyloidosis (APP_SL/PS1_M146L, APP/PS1_dE9, APP23, APP_SwDI, and 3xTg) presenting with compact, diffuse and intracellular plaques as well as in post mortem human-AD brains. The brains were then evaluated by histology to investigate the impact of size, compactness, and iron load of amyloid plaques on their detection by MRI. We show that Gd-stained MRI allows detection of compact amyloid plaques as small as 25 µm, independently of their iron load, in mice as well as in human-AD brains.

Neurobehavioural Toxicity of Iron Oxide Nanoparticles in Mice

Iron oxide nanoparticles (Fe₂O₃-NPs) are widely used in various biomedical applications, extremely in neurotheranostics. Simultaneously, Fe₂O₃-NP usage is of alarming concern, as its exposure to living systems causes deleterious effects due to its redox potential. However, study on the neurobehavioural impacts of Fe₂O₃-NPs is very limited. In this regard, adult male mice were intraperitoneally administered with Fe₂O₃-NPs (25 and 50 mg/kg body weight) once a week for 4 weeks. A significant change in locomotor behaviour and spatial memory was observed in Fe₂O₃-NP-treated animals. Damages to blood-brain barrier permeability by Fe₂O₃-NPs and their accumulation in brain regions were evidenced by Evan's blue staining, iron estimation and Prussian blue staining. Elevated nitric oxide, acetylcholinesterase, lactate dehydrogenase leakage and demyelination were observed in the Fe₂O₃-NP-exposed brain tissues. Imbalanced levels of ROS generation and antioxidant defence mechanism (superoxide dismutase and catalase) cause damages to lipids, proteins and DNA. PARP and cleaved caspase 3 expression levels were found to be increased in the Fe₂O₃-NP-exposed brain regions which confirms DNA damage and apoptosis. Thus, repeated Fe₂O₃-NP exposure causes neurobehavioural impairments by nanoparticle accumulation, oxidative stress and apoptosis in the mouse brain.

Novel Neuromodulation Techniques to Assess Interhemispheric Communication in Neural Injury and Neurodegenerative Diseases

Interhemispheric interaction has a major role in various neurobehavioral functions. Its disruption is a major contributor to the pathological changes in the setting of brain injury such as traumatic brain injury, peripheral nerve injury, and stroke, as well as neurodegenerative diseases. Because interhemispheric interaction has a crucial role in functional consequence in these neuropathological states, a review of noninvasive and state-of-the-art molecular based neuromodulation methods that focus on or have the potential to elucidate interhemispheric interaction have been performed. This yielded approximately 170 relevant articles on human subjects or animal models. There has been a recent surge of reports on noninvasive methods such as transcranial magnetic stimulation and transcranial direct current stimulation. Since these are noninvasive techniques with little to no side effects, their widespread use in clinical studies can be easily justified. The overview of novel neuromodulation methods and how they can be applied to study the role of interhemispheric communication in neural injury and neurodegenerative disease is provided. Additionally, the potential of each method in therapeutic use as well as investigating the pathophysiology of interhemispheric interaction in neurodegenerative diseases and brain injury is discussed. New technologies such as transcranial magnetic stimulation or transcranial direct current stimulation could have a great impact in understanding interhemispheric pathophysiology associated with acquired injury and neurodegenerative diseases, as well as designing improved rehabilitation therapies. Also, advances in molecular based neuromodulation techniques such as optogenetics and other chemical, thermal, and magnetic based methods provide new capabilities to stimulate or inhibit a specific brain location and a specific neuronal population.

In vivo microscopic voxel-based morphometry with a brain template to characterize strain-specific structures in the mouse brain

Hundreds of inbred mouse strains are established for use in a broad spectrum of basic research fields, including genetics, neuroscience, immunology, and cancer. Inbred mice exhibit identical intra-strain genetics and divergent inter-strain phenotypes. The cognitive and behavioral divergences must be controlled by the variances of structure and function of their brains; however, the underlying morphological features of strain-to-strain difference remain obscure. Here, in vivo microscopic magnetic resonance imaging was optimized to image the mouse brains by using an isotropic resolution of 80 μm. Next, in vivo templates were created from the data from four major inbred mouse strains (C57Bl/6, BALB/cBy, C3H/He, and DBA/2). A strain-mixed brain template was also created, and the template was then employed to establish automatic voxel-based morphometry (VBM) for the mouse brain. The VBM assessment revealed strain-specific brain morphologies concerning the gray matter volume of the four strains, with a smaller volume in the primary visual cortex for the C3H/He strain, and a smaller volume in the primary auditory cortex and field CA1 of the hippocampus for the DBA/2 strain. These findings would contribute to the basis of for understanding morphological phenotype of the inbred mouse strain and may indicate a relationship between brain morphology and strain-specific cognition and behavior.

Metal complexes for multimodal imaging of misfolded protein-related diseases

Aggregation of misfolded proteins and progressive polymerization of otherwise soluble proteins is a common hallmark of several highly debilitating and increasingly prevalent diseases, including amyotrophic lateral sclerosis, cerebral amyloid angiopathy, type II diabetes and Parkinson's, Huntington's and Alzheimer's diseases.

Superparamagnetic nanoparticle-enhanced MRI of Alzheimer's disease plaques and activated microglia in 3X transgenic mouse brains: Contrast optimization

PURPOSE

To optimize magnetic resonance imaging (MRI) of antibody-conjugated superparamagnetic nanoparticles for detecting amyloid-β plaques and activated microglia in a 3X transgenic mouse model of Alzheimer's disease.

MATERIALS AND METHODS

Ten 3X Tg mice were fed either chow or chow containing 100 ppm resveratrol. Four brains, selected from animals injected with either anti-amyloid targeted superparamagnetic iron oxide nanoparticles, or anti-Iba-1-conjugated FePt-nanoparticles, were excised, fixed with formalin, and placed in Fomblin for ex vivo MRI (11.7T) using multislice-multiecho, multiple gradient echo, rapid acquisition with relaxation enhancement, and susceptibility-weighted imaging (SWI). Aβ plaques and areas of neuroinflammation appeared as hypointense regions whose number, location, and Z-score were measured as a function of sequence type and echo time.

RESULTS

The MR contrast was due to the shortening of the transverse relaxation time of the plaque-adjacent tissue water. A theoretical analysis of this effect showed that the echo time was the primary determinant of plaque contrast and was used to optimize Z-scores. The Z-scores of the detected lesions varied from 21 to 34 as the echo times varied from 4 to 25 msec, with SWI providing the highest Z-score and number of detected lesions. Computation of the entire plaque and activated microglial distributions in 3D showed that resveratrol treatment led to a reduction of ∼24-fold of Aβ plaque density and ∼4-fold in microglial activation.

CONCLUSION

Optimized MRI of antibody-conjugated superparamagnetic nanoparticles served to reveal the 3D distributions of both Aβ plaques and activated microglia and to measure the effects of drug treatments in this 3X Tg model.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:574-588.

COB231 targets amyloid plaques in post-mortem human brain tissue and in an Alzheimer mouse model

Previous works have shown the interest of naturally fluorescent proflavine derivatives to label Abeta deposits in vitro. This study aimed to further characterize the properties of the proflavine 3-acetylamino-6-[3-(propargylamino)propanoyl]aminoacridine (COB231) derivative as a probe. This compound was therefore evaluated on human post-mortem and mice brain slices and in vivo in 18-month-old triple transgenic mice APPswe, PS1M146V and tauP301L (3xTgAD) mice presenting the main characteristics of Alzheimer's disease (AD). COB231 labelled amyloid plaques on brain slices of AD patients, and 3xTgAD mice at 10 and 0.1 μM respectively. However, no labelling of the neurofibrillary tangle-rich areas was observed either at high concentration or in the brain of fronto-temporal dementia patients. The specificity of this mapping was attested in mice using Thioflavin S and IMPY as positive controls of amyloid deposits. After intravenous injection of COB231 in old 3xTgAD mice, fluorescent amyloid plaques were detected in the cortex and hippocampus, demonstrating COB231 blood–brain barrier permeability. We also controlled the cellular localization of COB231 on primary neuronal cultures and showed that COB231 accumulates into the cytoplasm and not into the nucleus. Finally, using a viability assay, we only detected a slight cytotoxic effect of COB231 (< 10%) for the highest concentration (100 μM).

Metal Nanoparticles as Targeted Carriers Circumventing the Blood-Brain Barrier

Metal nanoparticles have been proposed as a carrier and a therapeutic agent in biomedical field because of their unique physiochemical properties. Due to these physicochemical properties, they can be used in different fields of biomedicine. In relation to this, plasmonic nanoparticles can be used for detection and photothermal destruction of tumor cells or toxic protein aggregates, and magnetic iron nanoparticles can be used for imaging and for hyperthermia of tumor cells. In addition, both therapy and imaging can be combined in one nanoparticle system, in a process called theranostics. Metal nanoparticles can be synthesized to modulate their size and shape, and conjugated with different ligands, which allow their application in drug delivery, diagnostics, and treatment of central nervous system diseases. This review is focused on the potential applications of metal nanoparticles and their capability to circumvent the blood-brain barrier (BBB). Although many articles have demonstrated delivery of metal nanoparticles to the brain by crossing the BBB after systemic administration, the percentage of the injected dose that reaches this organ is low in comparison to others, especially the liver and spleen. In connection with this drawback, we elaborate the architecture of the BBB and review possible mechanisms to cross this barrier by engineered nanoparticles. The potential uses of metal nanoparticles for treatment of disorders as well as related neurotoxicological considerations are also discussed. Finally, we bring up for discussion a direct and relatively simpler solution to the problem. We discuss this in detail after having proposed the use of the intranasal administration route as a way to circumvent the BBB. This route has not been extensively studied yet for metal nanoparticles, although it could be used as a research tool for mechanistic understanding and toxicity as well as an added value for medical practice.