SPION-enhanced magnetic resonance imaging of Alzheimer's disease plaques in AβPP/PS-1 transgenic mouse brain

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.

Role of lysosome in healing neurological disorders by nano-bioengineering

Lysosomes primarily recognized as center for cellular 'garbage-disposing-unit', which has recently emerged as a crucial regulator of cellular metabolism. This organelle is a well-known vital player in the pathology including neurodegenerative disorders. In pathological context, removal of intracellular damaged misfolded proteins, organelles and aggregates are ensured by 'Autophagy' pathway, which initially recognizes, engulfs and seals the toxic cargo at the cytosolic environment. Thereafter the cell completes the task of encapsulated cargo elimination upon delivery of them to the terminal compartment - lysosome, which contains acid hydrolases, that are capable of degrading the abnormal protein-lipid-repertoire. The merge between inseparable 'Autophagy' and 'Lysosomal' pathways evolved into 'Autophagy-Lysosome Pathway (ALP)', through which cell ultimately degrades and recycles bio-materials for metabolic needs. Dysregulation of any of the steps of the multi-step ALP can contribute to the development and progression of disorders including Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). Therefore, targeting differential steps of ALP or directly lysosomes using nano-bioengineering approaches holds great promise for therapeutic interventions. This review aims to explore the role of distal autophagy pathway and proximal lysosomal function, as cellular degradative and metabolic hubs, in healing neurological disorders and highlights the contributions of nano-bioengineering in this field. Despite multiple challenges, this review underscores the immense potential of integrating autophagy-lysosomal biology with nano-bioengineering to revolutionize the field and provide novel therapeutic avenues for tackling neurological-neurodegenerative-disorders.

A review on nanotechnological perspective of "the amyloid cascade hypothesis" for neurodegenerative diseases

Neurodegenerative diseases (NDs) are characterized by progressive degeneration of neurons which deteriorates the brain functions. An early detection of the onset of NDs is utmost important, as it will provide the fast treatment strategies to prevent further progression of the disease. Conventionally, accurate diagnosis of the brain related disorders is difficult in their early phase. To solve this problem, nanotechnology based neurofunctional imaging and biomarker detection techniques have been developed which allows high specificity and sensitivity towards screening and diagnosis of NDs. Another challenge to treat the brain related disorders is to overcome the complex integrity of blood-brain-barrier (BBB) for the delivery of theranostic agents. Fortunately, utilization of nanomaterials has been pursued as promising strategy to address this challenge. Herein, we critically highlighted the recent improvements in the field of neurodiagnostic and therapeutic approaches involving innovative strategies for diagnosis, and inhibition of protein aggregates. We have provided particular emphasis on the use of nanotechnology which can push forward the blooming research growth in this field to win the battle against devastating NDs.

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.

Machine learning assisted-nanomedicine using magnetic nanoparticles for central nervous system diseases

Magnetic nanoparticles possess unique properties distinct from other types of nanoparticles developed for biomedical applications. Their unique magnetic properties and multifunctionalities are especially beneficial for central nervous system (CNS) disease therapy and diagnostics, as well as targeted and personalized applications using image-guided therapy and theranostics. This review discusses the recent development of magnetic nanoparticles for CNS applications, including Alzheimer's disease, Parkinson's disease, epilepsy, multiple sclerosis, and drug addiction. Machine learning (ML) methods are increasingly applied towards the processing, optimization and development of nanomaterials. By using data-driven approach, ML has the potential to bridge the gap between basic research and clinical research. We review ML approaches used within the various stages of nanomedicine development, from nanoparticle synthesis and characterization to performance prediction and disease diagnosis.

A critical review on the role of nanotheranostics mediated approaches for targeting β amyloid in Alzheimer's

Alzheimer's is one of the most common neurodegenerative illnesses that affect brain cellular function. In this disease, the neurons in the brain are considered to be decaying steadily but consistently by the accumulation of amyloid mass, particularly the β-amyloids, amyloid proteins, and Tau proteins. The most responsible amyloid-proteins are amyloid-40 and amyloid-42, which have a high probability of accumulating in excess over the brain cell, interfering with normal brain cell function and triggering brain cell death. The advancement of pharmaceutical sciences leads to the development of Nanotheranostics technology, which may be used to diagnose and treat Alzheimer's. They are the colloidal nanoparticles functionalised with the therapeutic moiety as well as a diagnostic moiety. This article discusses the prognosis of Alzheimer's, various nanotheranostics approaches (nanoparticles, quantum dots, aptamers, dendrimers, etc), and their recent advancement in managing Alzheimer's. Also, various in-vitro and in-vivo diagnostic methodologies were discussed with respect to nanotheranostics.

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.

Evolution of Detecting Early Onset of Alzheimer's Disease: From Neuroimaging to Optical Immunoassays

Alzheimer's disease (AD) is a pathological disorder defined by the symptoms of memory loss and deterioration of cognitive abilities over time. Although the etiology is complex, it is mainly associated with the accumulation of toxic amyloid-β peptide (Aβ) aggregates and tau protein-induced neurofibrillary tangles (NFTs). Even now, creating non-invasive, sensitive, specific, and cost-effective diagnostic methods for AD remains challenging. Over the past few decades, polymers, and nanomaterials (e.g., nanodiamonds, nanogold, quantum dots) have become attractive and practical tools in nanomedicine for diagnosis and treatment. This review focuses on current developments in sensing methods such as enzyme-linked immunosorbent assay (ELISA) and surface-enhanced Raman scattering (SERS) to boost the sensitivity in detecting related biomarkers for AD. In addition, optical analysis platforms such as ELISA and SERS have found increasing popularity among researchers due to their excellent sensitivity and specificity, which may go as low as the femtomolar range. While ELISA offers easy technological usage and high throughput, SERS has the advantages of improved mobility, simple electrical equipment integration, and lower cost. Both portable optical sensing techniques are highly superior in terms of sensitivity, specificity, human application, and practicality, enabling the early identification of AD biomarkers.

Role of Nanomedicine-Based Therapeutics in the Treatment of CNS Disorders

Central nervous system disorders, especially neurodegenerative diseases, are a public health priority and demand a strong scientific response. Various therapy procedures have been used in the past, but their therapeutic value has been insufficient. The blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier is two of the barriers that protect the central nervous system (CNS), but are the main barriers to medicine delivery into the CNS for treating CNS disorders, such as brain tumors, Parkinson's disease, Alzheimer's disease, and Huntington's disease. Nanotechnology-based medicinal approaches deliver valuable cargos targeting molecular and cellular processes with greater safety, efficacy, and specificity than traditional approaches. CNS diseases include a wide range of brain ailments connected to short- and long-term disability. They affect millions of people worldwide and are anticipated to become more common in the coming years. Nanotechnology-based brain therapy could solve the BBB problem. This review analyzes nanomedicine's role in medication delivery; immunotherapy, chemotherapy, and gene therapy are combined with nanomedicines to treat CNS disorders. We also evaluated nanotechnology-based approaches for CNS disease amelioration, with the intention of stimulating the immune system by delivering medications across the BBB.

Structural and functional imaging of brains

Analyzing the complex structures and functions of brain is the key issue to understanding the physiological and pathological processes. Although neuronal morphology and local distribution of neurons/blood vessels in the brain have been known, the subcellular structures of cells remain challenging, especially in the live brain. In addition, the complicated brain functions involve numerous functional molecules, but the concentrations, distributions and interactions of these molecules in the brain are still poorly understood. In this review, frontier techniques available for multiscale structure imaging from organelles to the whole brain are first overviewed, including magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography (PET), serial-section electron microscopy (ssEM), light microscopy (LM) and synchrotron-based X-ray microscopy (XRM). Specially, XRM for three-dimensional (3D) imaging of large-scale brain tissue with high resolution and fast imaging speed is highlighted. Additionally, the development of elegant methods for acquisition of brain functions from electrical/chemical signals in the brain is outlined. In particular, the new electrophysiology technologies for neural recordings at the single-neuron level and in the brain are also summarized. We also focus on the construction of electrochemical probes based on dual-recognition strategy and surface/interface chemistry for determination of chemical species in the brain with high selectivity and long-term stability, as well as electrochemophysiological microarray for simultaneously recording of electrochemical and electrophysiological signals in the brain. Moreover, the recent development of brain MRI probes with high contrast-to-noise ratio (CNR) and sensitivity based on hyperpolarized techniques and multi-nuclear chemistry is introduced. Furthermore, multiple optical probes and instruments, especially the optophysiological Raman probes and fiber Raman photometry, for imaging and biosensing in live brain are emphasized. Finally, a brief perspective on existing challenges and further research development is provided.

Superparamagnetic Iron Oxide Nanoparticles for Immunotherapy of Cancers through Macrophages and Magnetic Hyperthermia

Cancer immunotherapy has tremendous promise, but it has yet to be clinically applied in a wider variety of tumor situations. Many therapeutic combinations are envisaged to improve their effectiveness. In this way, strategies capable of inducing immunogenic cell death (e.g., doxorubicin, radiotherapy, hyperthermia) and the reprogramming of the immunosuppressive tumor microenvironment (TME) (e.g., M2-to-M1-like macrophages repolarization of tumor-associated macrophages (TAMs)) are particularly appealing to enhance the efficacy of approved immunotherapies (e.g., immune checkpoint inhibitors, ICIs). Due to their modular construction and versatility, iron oxide-based nanomedicines such as superparamagnetic iron oxide nanoparticles (SPIONs) can combine these different approaches in a single agent. SPIONs have already shown their safety and biocompatibility and possess both drug-delivery (e.g., chemotherapy, ICIs) and magnetic capabilities (e.g., magnetic hyperthermia (MHT), magnetic resonance imaging). In this review, we will discuss the multiple applications of SPIONs in cancer immunotherapy, focusing on their theranostic properties to target TAMs and to generate MHT. The first section of this review will briefly describe immune targets for NPs. The following sections will deal with the overall properties of SPIONs (including MHT). The last section is dedicated to the SPION-induced immune response through its effects on TAMs and MHT.

Selection of single domain anti-transferrin receptor antibodies for blood-brain barrier transcytosis using a neurotensin based assay and histological assessment of target engagement in a mouse model of Alzheimer's related amyloid-beta pathology

The blood-brain barrier (BBB) presents a major obstacle in developing specific diagnostic imaging agents for many neurological disorders. In this study we aimed to generate single domain anti-mouse transferrin receptor antibodies (anti-mTfR VHHs) to mediate BBB transcytosis as components of novel MRI molecular contrast imaging agents. Anti-mTfR VHHs were produced by immunizing a llama with mTfR, generation of a VHH phage display library, immunopanning, and in vitro characterization of candidates. Site directed mutagenesis was used to generate additional variants. VHH fusions with neurotensin (NT) allowed rapid, hypothermia-based screening for VHH-mediated BBB transcytosis in wild-type mice. One anti-mTfR VHH variant was fused with an anti-amyloid-beta (Aβ) VHH dimer and labeled with fluorescent dye for direct assessment of in vivo target engagement in a mouse model of AD-related Aβ plaque pathology. An anti-mTfR VHH called M1 and variants had binding affinities to mTfR of <1nM to 1.52nM. The affinity of the VHH binding to mTfR correlated with the efficiency of the VHH-NT induced hypothermia effects after intravenous injection of 600 nmol/kg body weight, ranging from undetectable for nonbinding mutants to -6°C for the best mutants. The anti-mTfR VHH variant M1P96H with the strongest hypothermia effect was fused to the anti-Aβ VHH dimer and labeled with Alexa647; the dye-labeled VHH fusion construct still bound both mTfR and Aβ plaques at concentrations as low as 0.22 nM. However, after intravenous injection at 600 nmol/kg body weight into APP/PS1 transgenic mice, there was no detectible labeling of plaques above control levels. Thus, NT-induced hypothermia did not correlate with direct target engagement in cortex, likely because the concentration required for NT-induced hypothermia was lower than the concentration required to produce in situ labeling. These findings reveal an important dissociation between NT-induced hypothermia, presumably mediated by hypothalamus, and direct engagement with Aβ-plaques in cortex. Additional methods to assess anti-mTfR VHH BBB transcytosis will need to be developed for anti-mTfR VHH screening and the development of novel MRI molecular contrast agents.

Highly sensitive Curcumin-conjugated nanotheranostic platform for detecting amyloid-beta plaques by magnetic resonance imaging and reversing cognitive deficits of Alzheimer's disease via NLRP3-inhibition

BACKGROUND

Alzheimer's disease (AD) is the most common neurodegenerative disorder without effective therapy and lack diagnosis strategy for preclinical AD patients. There is an urgent need for development of both early diagnosis and therapeutic intervention of AD.

RESULTS

Herein, we developed a nanotheranostics platform consisting of Curcumin (Cur), an anti-inflammatory molecule, and superparamagnetic iron oxide (SPIO) nanoparticles encapsulated by diblock 1,2-dio-leoyl-sn-glycero-3-phosphoethanolamine-n-[poly(ethylene glycol)] (DSPE-PEG) that are modified with CRT and QSH peptides on its surface. Furthermore, we demonstrated that this multifunctional nanomaterial efficiently reduced β-amyloid plaque burden specifically in APP/PS1 transgenic mice, with the process noninvasively detected by magnetic resonance imaging (MRI) and the two-dimensional MRI images were computed into three-dimension (3D) plot. Our data demonstrated highly sensitive in vivo detection of β-amyloid plaques which more closely revealed real deposition of Aβ than previously reported and we quantified the volumes of plaques for the first time based on 3D plot. In addition, memory deficits of the mice were significantly rescued, probably related to inhibition of NLR Family Pyrin Domain Containing 3 (NLRP3) inflammasomes.

CONCLUSIONS

Gathered data demonstrated that this theranostic platform may have both early diagnostic and therapeutic potential in AD.

The Emerging Applications of Nanotechnology in Neuroimaging: A Comprehensive Review

Neuroimaging modalities such as computer tomography and magnetic resonance imaging have greatly improved in their ability to achieve higher spatial resolution of neurovascular and soft tissue neuroanatomy, allowing for increased accuracy in the diagnosis of neurological conditions. However, the use of conventional contrast agents that have short tissue retention time and associated renal toxicities, or expensive radioisotope tracers that are not widely available, continue to limit the sensitivity of these imaging modalities. Nanoparticles can potentially address these shortcomings by enhancing tissue retention and improving signal intensity in the brain and neural axis. In this review, we discuss the use of different types of nanotechnology to improve the detection, diagnosis, and treatment of a wide range of neurological diseases.

Polysorbate-coated mesoporous silica nanoparticles as an efficient carrier for improved rivastigmine brain delivery

Targeted delivery of neurological therapeutic to the brain has been attracting more and more attention to the treatment of central nervous system (CNS) diseases. Nonetheless, the main obstacle in this road map is the existence of a blood-brain barrier (BBB) which limits the penetration efficiency of most CNS drugs into the brain parenchyma. This present investigation describes a facile synthetic strategy to prepare a highly biocompatible calcium-doped mesoporous silica nanoparticles (MSNs) functionalized by polysorbate-80 (PS) as targeting ligand to deliver rivastigmine (RV) into the brain via crossing the BBB. The developed nanosystem was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), Zeta potential, and N₂-adsorption-desorption analysis. In vitro hemolysis studies were carried out to confirm the biocompatibility of the nanocarriers. Our in vivo studies in an animal model of rats showed that the RV-loaded nanosystem was able to enhance the brain-to-plasma concentration ratio, brain uptake clearance, and plasma elimination half-life of the drug compared to the free one drug following intravenous (IV) administration. The results revealed that functionalization of MSNs by PS is crucial to deliver RV into the brain, suggesting PS-functionalized MSNs could be an effective carrier to deliver RV to the brain while overcoming BBB.

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.

Pharmacokinetics of Single Domain Antibodies and Conjugated Nanoparticles Using a Hybrid near Infrared Method

Iron oxide nanoparticles and single domain antibodies from camelids (VHHs) have been increasingly recognized for their potential uses for medical diagnosis and treatment. However, there have been relatively few detailed characterizations of their pharmacokinetics (PK). The aim of this study was to develop imaging methods and pharmacokinetic models to aid the future development of a novel family of brain MRI molecular contrast agents. An efficient near-infrared (NIR) imaging method was established to monitor VHH and VHH conjugated nanoparticle kinetics in mice using a hybrid approach: kinetics in blood were assessed by direct sampling, and kinetics in kidney, liver, and brain were assessed by serial in vivo NIR imaging. These studies were performed under "basal" circumstances in which the VHH constructs and VHH-conjugated nanoparticles do not substantially interact with targets nor cross the blood brain barrier. Using this approach, we constructed a five-compartment PK model that fits the data well for single VHHs, engineered VHH trimers, and iron oxide nanoparticles conjugated to VHH trimers. The establishment of the feasibility of these methods lays a foundation for future PK studies of candidate brain MRI molecular contrast agents.

Impact of the Sound of Magnetic Resonance Imaging Pulse Sequences in Awake Mice

Magnetic resonance imaging (MRI) is a research field of high interest as the implementation of new imaging modalities can significantly improve clinical diagnosis of several human pathologies. Awake nonhuman animals in the laboratory are being used in MRI pre-clinical systems for the validation of new imaging techniques, but animal welfare concerns emerge as MRI pulse sequences produce extremely loud sounds, up to 120 dB. Consequently, it is unclear how stressful these sounds are to the animals. Here, the impact of these sounds in the rodent behavior and physiology was evaluated. To achieve this, C57BL6/J mice were divided into two groups: a group exposed to sounds of typical pulse sequences used in imaging and a control group that was not exposed to those sounds. Mice have been tested in the open field and elevated plus maze to monitor baseline behavior and a hormonal stress biomarker was assayed to assess acute stress. The results indicate that the pulse sequences used in MRI are transient stressors that overall do not impact the behavioral status of the animals.

Nanomedicine against Alzheimer's and Parkinson's Disease

Alzheimer's and Parkinson's are the two most rampant neurodegenerative disorders worldwide. Existing treatments have a limited effect on the pathophysiology but are unable to fully arrest the progression of the disease. This is due to the inability of these therapeutic molecules to efficiently cross the blood-brain barrier. We discuss how nanotechnology has enabled researchers to develop novel and efficient nano-therapeutics against these diseases. The development of nanotized drug delivery systems has permitted an efficient, site-targeted, and controlled release of drugs in the brain, thereby presenting a revolutionary therapeutic approach. Nanoparticles are also being thoroughly studied and exploited for their role in the efficient and precise diagnosis of neurodegenerative conditions. We summarize the role of different nano-carriers and RNAi-conjugated nanoparticle-based therapeutics for their efficacy in pre-clinical studies. We also discuss the challenges underlying the use of nanomedicine with a focus on their route of administration, concentration, metabolism, and any toxic effects for successful therapeutics in these diseases.

Organoids: A new approach in toxicity testing of nanotherapeutics

Nanotechnology has revolutionized diverse fields, which include agriculture, the consumer market, medicine, and other fields. Widespread use of nanotechnology-based products has led to increased prevalence of these novel formulations in the environment, which has raised concerns regarding their deleterious effects. The application of nanotechnology-based formulations into clinical use is hampered by the lack of the availability of effective in vitro systems, which could accurately assess their in vivo toxic effects. A plethora of studies has shown the hazardous effects of nanoparticle-based formulations in two-dimensional in vitro cell cultures and animal models. These have some associated disadvantages when used for the evaluation of nano-toxicity. Organoid technology fills the space between existing two-dimensional cell line culture and in vivo models. The uniqueness of organoids over other systems for evaluating toxicity caused by nano-drug formulation includes them being a co-culture of diverse cell types, dynamic flow within them that simulates the actual flow of nanoparticles within biological systems, extensive cell-cell, cell-matrix interactions, and a tissue-like morphology. Thus, it mimics the actual tissue microenvironment and, subsequently, provides an opportunity to study drug metabolism and toxico-dynamics of nanotechnology-based novel formulations. The use of organoids in the evaluation of nano-drug toxicity is in its infancy. A limited number of studies conducted so far have shown good predictive value and efficiently significant data correlation with the clinical trials. In this review, we attempt to introduce organoids of the liver, lungs, brain, kidney intestine, and potential applications to evaluate toxicity caused by nanoparticles.

Nanoconstructs as a versatile tool for detection and diagnosis of Alzheimer biomarkers

The current review focuses towards the advancements made in the past decade in the field of nanotechnology for the early Alzheimer's disease (AD) diagnosis. This review includes the application of nanomaterials and nanosensors for the early detection of the main AD biomarkers (amyloid beta, phosphorylated tau, apolipoprotein E4 allele or APOE4, microRNAs, cholesterol, hydrogen peroxide etc) in biological fluids, to detect the biomarkers at a very low concentration ranging in pico, femto and even atto molar concentrations. The field of drug development has always aimed and is constantly working on developing disease modifying drugs, but these drugs will only succeed when given in the early disease stages. Thus, developing efficient diagnostic tools is of vital importance. Various nanomaterials such as liposomes; dendrimers; polymeric nanoparticles; coordination polymers; inorganic nanoparticles such as silica, manganese oxide, zinc oxide, iron oxide, super paramagnetic iron oxides; quantum dots, silver nanoparticles, gold nanoparticles, and carbon based nanostructures (carbon nanotubes, graphene oxide, nanofibres, nanodiamonds, carbon dots); Up-conversion nanoparticles; 2D nanomaterials; and radioactive nanoprobes have been used in constructing and improving efficiency of nano-sensors for AD biosensing at an early stage of diagnosis.

Applications of magnetic particle imaging in the dementias

PURPOSE OF REVIEW

This review discusses recent developments in the application of magnetic particle imaging (MPI) to dementia research.

RECENT FINDINGS

MPI is a tracer method that is currently in the preclinical development stage. It provides high sensitivity for the detection and localization of magnetic nanoparticles with very high spatial and temporal resolution and a similar application spectrum as PET. Unlike MRI, the MPI signal is not contaminated by background signal from tissues and is highly quantifiable in terms of local tracer concentrations. These properties make the technology ideally suited for localization of specific targets or quantification of vascular parameters. MPI uses magnetic nanoparticles which can be modified by various coatings, and by adding ligands (i.e. peptides or antibodies) for specific targeting. This makes MPI an attractive tool for the potential detection of abnormal protein deposits, such as Aβ plaques, with greater specificity than MRI. Neural stem cells can also be labelled with these nanoparticles ex vivo to monitor their migration in vivo.

SUMMARY

The capabilities of MPI opens the potential for several applications of MPI in neurocognitive disorders, including vascular imaging, detection of amyloid plaques and potentially other pathological hallmarks of Alzheimer's disease and stem-cell tracking.

Dendrimer Architectonics to Treat Cancer and Neurodegenerative Diseases with Implications in Theranostics and Personalized Medicine

Integration of diagnostic and therapeutic functions in a single platform namely theranostics has become a cornerstone for personalized medicine. Theranostics platform facilitates noninvasive detection and treatment while allowing the monitoring of disease progression and therapeutic efficacy in case of chronic conditions of cancer and Alzheimer's disease (AD). Theranostic tools function by themselves or with the aid of carrier, viz. liposomes, micelles, polymers, or dendrimers. The dendrimer architectures (DA) are well-characterized molecular nanoobjects with a large number of terminal functional groups to enhance solubility and offer multivalency and multifunctional properties. Various noninvasive diagnostic tools like magnetic resonance imaging (MRI), computed tomography (CT), gamma scintigraphy, and optical techniques have been accomplished utilizing DAs for simultaneous imaging and drug delivery. Obstacles in the formulation design, drug loading, payload delivery, biocompatibility, overcoming cellular membrane and blood-brain barrier (BBB), and systemic circulation remain a bottleneck in translational efforts. This review focuses on the diagnostic, therapeutic and theranostic potential of DA-based nanocarriers in treating cancer and neurodegenerative disorders like AD and Parkinson's disease (PD), among others. In view of the inverse relationship between cancer and AD, designing suitable DA-based theranostic nanodrug with high selectivity has tremendous implications in personalized medicine to treat cancer and neurodegenerative disorders.

In vitro and in vivo models for anti-amyloidosis nanomedicines

Amyloid diseases are global epidemics characterized by the accumulative deposits of cross-beta amyloid fibrils and plaques. Despite decades of intensive research, few solutions are available for the diagnosis, treatment, and prevention of these debilitating diseases. Since the early work on the interaction of human β₂-microglobulin and nanoparticles by Linse et al. in 2007, the field of amyloidosis inhibition has gradually evolved into a new frontier in nanomedicine offering numerous interdisciplinary research opportunities, especially for materials, chemistry and biophysics. In this review we summarise, for the first time, the in vitro and in vivo models employed thus far in the field of anti-amyloidosis nanomedicines. Based on this systematic summary, we bring forth the notion that, due to the complex and often overlapping physiopathologies of amyloid diseases, there is a crucial need for the appropriate use of in vitro and in vivo models for validating novel anti-amyloidosis nanomedicines, and there is a crucial need for the development of new animal models that reflect the behavioural, symptomatic and cross-talk hallmarks of amyloid diseases such as Alzheimer's (AD), Parkinson's (PD) diseases and type 2 diabetes (T2DM).

A review on advances of treatment modalities for Alzheimer's disease

Alzheimer's disease (AD) is a multifactorial neurodegenerative disease which is mainly characterized by progressive impairment in cognition, emotion, language and memory in older population. Considering the impact of AD, formulations of pharmaceutical drugs and cholinesterase inhibitors have been widely propagated, receiving endorsement by FDA as a form of AD treatment. However, these medications were gradually discovered to be ineffective in removing the root of AD pathogenesis but merely targeting the symptoms so as to improve a patient's cognitive outcome. Hence, a search for better disease-modifying alternatives is put into motion. Having a clear understanding of the neuroprotective mechanisms and diverse properties undertaken by specific genes, antibodies and nanoparticles is central towards designing novel therapeutic agents. In this review, we provide a brief introduction on the background of Alzheimer's disease, the biology of blood-brain barrier, along with the potentials and drawbacks associated with current therapeutic treatment avenues pertaining to gene therapy, immunotherapy and nanotherapy for better diagnosis and management of Alzheimer's disease.

Recent Advances in Nanotherapeutic Interventions for the Treatment of Alzheimer's Disease

Alzheimer's disease (AD), with impairment of learning and memory as the common clinical manifestations, is one of the most challenging diseases affecting individuals, their families and society as a whole. The fact that its prevalence is escalating rapidly, with the total number of AD patients estimated to reach 115.4 million by 2050, has made the disease a very challenging ailment worldwide. Several biological barriers like the bloodbrain barrier (BBB), drug efflux by P-glycoprotein and the blood-cerebrospinal fluid barrier restrict the delivery of conventional AD drugs to the central nervous system (CNS), thereby limiting their effectiveness. In order to overcome the above physiological barriers, the development of nanomedicines has been extensively explored. The present review provides an insight into the pathophysiology of AD and risk factors associated with AD. Besides, various nanoformulations reported in the literature for the diagnosis and treatments of AD have been classified and summarised. The patented nanoformulations for AD and details of nanoformulations which are in clinical trials are also mentioned. The review would be helpful to researchers and scientific community by providing them with information related to the recent advances in nanointerventions for the diagnosis and treatment of AD, which they can further explore for better management of the disease. However, although the nanotherapeutics for managing AD have been extensively explored, the factors which hinder their commercialisation, the toxicity concern being one of them, need to be addressed so that effective nanotherapeutics for AD can be developed for clinical use.

Longitudinal monitoring of microglial/macrophage activation in ischemic rat brain using Iba-1-specific nanoparticle-enhanced magnetic resonance imaging

Microglial/macrophage activation plays a dual role in response to brain injury after a stroke, promoting early neuroinflammation and benefit for neurovascular recovery. Therefore, the dynamics of stroke-induced cerebral microglial/macrophage activation are of substantial interest. This study used novel anti-Iba-1-targeted superparamagnetic iron-platinum (FePt) nanoparticles in conjunction with magnetic resonance imaging (MRI) to measure the spatiotemporal changes of the microglial/macrophage activation in living rat brain for four weeks post-stroke. Ischemic lesion areas were identified and measured using T₂-weighted MR images. After injection of the FePt-nanoparticles, T₂*-weighted MR images showed that the nanoparticles were seen solely in brain regions that coincided with areas of active microglia/macrophages detected by post-mortem immunohistochemistry. Good agreement in morphological and distributive dynamic changes was also observed between the Fe⁺-cells and the Iba-1⁺-microglia/macrophages. The spatiotemporal changes of nanoparticle detected by T₂*-weighted images paralleled the changes of microglial/macrophage activation and phenotypes measured by post-mortem immunohistochemistry over the four weeks post-stroke. Maximum microglial/macrophage activation occurred seven days post-stroke for both measures, and the diminished activation found after two weeks continued to four weeks. Our results suggest that nanoparticle-enhanced MRI may constitute a novel approach for monitoring the dynamic development of neuroinflammation in living animals during the progression and treatment of stroke.

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).

Key for crossing the BBB with nanoparticles: the rational design

Central nervous system diseases are a heavy burden on society and health care systems. Hence, the delivery of drugs to the brain has gained more and more interest. The brain is protected by the blood-brain barrier (BBB), a selective barrier formed by the endothelial cells of the cerebral microvessels, which at the same time acts as a bottleneck for drug delivery by preventing the vast majority of drugs to reach the brain. To overcome this obstacle, drugs can be loaded inside nanoparticles that can carry the drug through the BBB. However, not all particles are able to cross the BBB and a multitude of factors needs to be taken into account when developing a carrier system for this purpose. Depending on the chosen pathway to cross the BBB, nanoparticle material, size and surface properties such as functionalization and charge should be tailored to fit the specific route of BBB crossing.

Genotoxicity and biocompatibility of superparamagnetic iron oxide nanoparticles: Influence of surface modification on biodistribution, retention, DNA damage and oxidative stress

Superparamagnetic iron oxide nanoparticles (SPION) require stable surface modifications to render safe nanocapsules for biomedical applications. Herein, two types of surface modified poly(lactic-co-glycolic acid)-encapsulated SPION were synthesized using either α-tocopheryl-polyetheleneglycol-succinate (TPGS) or didodecyl-dimethyl-ammonium-bromide (DMAB) as surfactants by emulsification. SPION-TPGS (180 nm) was larger than SPION-DMAB (25 nm) and uncoated SPION (10 nm). Both formulations were positively charged and induced lower cyto-genotoxicity and ROS generation than uncoated SPION in human lymphocytes. SPION-DMAB was least cyto-genotoxic among the three. Based on these results, mice were gavaged with the formulations for 5 consecutive days and biocompatibility studies were performed on the 7th and 21st days. ICP-AES and Prussian blue staining revealed the internalization of SPION-DMAB in brain and spleen, and SPION-TPGS in liver and kidney on day 7. This was correlated with high DNA damage and oxidative stress in the same organs. Substantial clearance of Fe was accompanied by reduced genotoxicity and oxidative stress on day 21. Therefore, SPION-DMAB can be further studied for oral drug delivery to the brain and imaging of cerebral tissue without any functional ligand or external magnetic field.

Superparamagnetic Iron Oxide Nanoparticles-Current and Prospective Medical Applications

The recent, fast development of nanotechnology is reflected in the medical sciences. Superparamagnetic Iron Oxide Nanoparticles (SPIONs) are an excellent example. Thanks to their superparamagnetic properties, SPIONs have found application in Magnetic Resonance Imaging (MRI) and magnetic hyperthermia. Unlike bulk iron, SPIONs do not have remnant magnetization in the absence of the external magnetic field; therefore, a precise remote control over their action is possible. This makes them also useful as a component of the advanced drug delivery systems. Due to their easy synthesis, biocompatibility, multifunctionality, and possibility of further surface modification with various chemical agents, SPIONs could support many fields of medicine. SPIONs have also some disadvantages, such as their high uptake by macrophages. Nevertheless, based on the ongoing studies, they seem to be very promising in oncological therapy (especially in the brain, breast, prostate, and pancreatic tumors). The main goal of our paper is, therefore, to present the basic properties of SPIONs, to discuss their current role in medicine, and to review their applications in order to inspire future developments of new, improved SPION systems.

Effect of superparamagnetic nanoparticles coated with various electric charges on α-synuclein and β-amyloid proteins fibrillation process

Background

Most of nanoparticles are nontoxic and have high absorption capability. Therefore, nanoparticles binding can effectively restrain fibrillation of β-amyloid and α-synuclein proteins and eventually prevent the toxicity of pathogenesis peptide of Alzheimer. Super paramagnetic iron oxide nanoparticles (SPIONs) contain iron oxide core which can be connected to a special part through magnetic coating.

Materials and methods

In this study, the effect of SPIONs with different charges was simultaneously examined on the fibrillation of both β-amyloid and α-synuclein proteins by applying Thioflavin-T assay.

Results

According to the results of the investigation on amyloid-fibrillation mechanism in both β-amyloids and α-synucleins, it was revealed that negatively-charged nanoparticles encoded to –COOH by dextran-coating were able to have a considerable absorption decrease from 17,000–12,000 after 320 minutes delay to lag phase and decrease in binding level of thioflavin-T particles to β-sheets.

Conclusion

The different concentrations of these nanoparticles and special coating of each particle had an effect on the kinetics of β-amyloid and α-synuclein fibrillations.

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.

Therapeutic nanoplatforms and delivery strategies for neurological disorders

The major neurological disorders found in a central nervous system (CNS), such as brain tumors, Alzheimer's diseases, Parkinson's diseases, and Huntington's disease, have led to devastating outcomes on the human public health. Of these disorders, early diagnostics remains poor, and no treatment has been successfully discovered; therefore, they become the most life-threatening medical burdens worldwide compared to other major diseases. The major obstacles for the drug discovery are the presence of a restrictive blood-brain barrier (BBB), limiting drug entry into brains and undesired neuroimmune activities caused by untargeted drugs, leading to irreversible neuronal damages. Recent advances in nanotechnology have contributed to the development of novel nanoplatforms and effective delivering strategies to improve the CNS disorder treatment while less disturbing brain systems. The nanoscale drug carriers, including liposomes, dendrimers, viral capsids, polymeric nanoparticles, silicon nanoparticles, and magnetic/metallic nanoparticles, enable the effective drug delivery penetrating across the BBB, the aforementioned challenges in the CNS. Moreover, drugs encapsulated by the nanocarriers can reach further deeper into targeting regions while preventing the degradation. In this review, we classify novel disease hallmarks incorporated with emerging nanoplatforms, describe promising approaches for improving drug delivery to the disordered CNS, and discuss their implications for clinical practice.

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.

The Delivery Challenge in Neurodegenerative Disorders: The Nanoparticles Role in Alzheimer's Disease Therapeutics and Diagnostics

Alzheimer’s disease (AD) is one of the main causes of disability and dependency among elderly people. AD is a neurodegenerative disorder characterized by a progressive and irreversible cognitive impairment, whose etiology is unclear because of the complex molecular mechanisms involved in its pathophysiology. A global view of the AD pathophysiology is described in order to understand the need for an effective treatment and why nanoparticles (NPs) could be an important weapon against neurodegenerative diseases by solving the general problem of poor delivery into the central nervous system (CNS) for many drugs. Drug delivery into the CNS is one of the most challenging objectives in pharmaceutical design, due to the limited access to the CNS imposed by the blood-brain barrier (BBB). The purpose of this review is to present a comprehensive overview of the use of NPs as delivery systems for therapeutic and diagnostic purposes in models of AD.

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.

Nanotechnology Based Theranostic Approaches in Alzheimer's Disease Management: Current Status and Future Perspective

BACKGROUND

Alzheimer's disease (AD), a cognitive dysfunction/dementia state amongst the elders is characterized by irreversible neurodegeneration due to varied pathophysiology. Up till now, anti-AD drugs having different pharmacology have been developed and used in clinic. Yet, these medications are not curative and only lowering the AD associated symptoms. Improvement in treatment outcome required drug targeting across the blood-brain barrier (BBB) to the central nervous system (CNS) in optimal therapeutic concentration. Nanotechnology based diagnostic tools, drug carriers and theranostics offer highly sensitive molecular detection, effective drug targeting and their combination. Over the past decade, significant works have been done in this area and we have seen very remarkable outocome in AD therapy. Various nanoparticles from organic and inorganic nanomaterial category have successfully been investigated against AD.

CONCLUSION

This paper discussed the role of nanoparticles in early detection of AD, effective drug targeting to brain and theranostic (diagnosis and therapy) approaches in AD's management.

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.

Challenges and opportunities in developing targeted molecular imaging to determine inner ear defects of sensorineural hearing loss

The development of inner ear gene carriers and delivery systems has enabled genetic defects to be repaired and hearing to be restored in mouse models. Today, promising advances in translational therapies provide confidence that targeted molecular therapy for inner ear diseases will be developed. Unfortunately, the currently available non-invasive modalities, such as Computerized Tomography scan or Magnetic Resonance Imaging provide insufficient resolution to identify most pathologies of the human inner ear, even when the current generation of contrast agents is utilized. The development of targeted contrast agents may play a critical role in determining the cause of, and treatment for, sensorineural hearing loss. Such agents should be able to pass through the cochlea barriers, possess minimal cytotoxicity, and easily conjugate to a targeting agent, without distorting the anatomic details. This review focuses on a series of contrast agents which may fit these criteria for potential clinical application.

Targeted Superparamagnetic Iron Oxide Nanoparticles for In Vivo Magnetic Resonance Imaging of T-Cells in Rheumatoid Arthritis

PURPOSE

The purpose of the study is to develop a targeted nanoparticle platform for T cell labeling and tracking in vivo.

PROCEDURES

Through carboxylation of the polyethylene glycol (PEG) surface of SPION, carboxylated-PEG-SPION (IOPC) was generated as a precursor for further conjugation with the targeting probe. The IOPC could readily cross-link with a variety of amide-containing molecules by exploiting the reaction between 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide and N-hydroxysuccinimide. The subsequent conjugation of monoclonal anti-CD3 antibody with IOPC made it possible to construct a magnetic resonance imaging (MRI) contrast agente (CA) that targets T cells, named IOPC-CD3.

RESULTS

IOPC-CD3 was found to have high transverse relaxivity, good targeting selectivity, and good safety profile in vitro. The utility of this newly synthesized CA was explored in an in vivo rodent collagen-induced arthritis (CIA) model of rheumatoid arthritis. Serial MRI experiments revealed a selective decrease in the signal-to-noise ratio of the femoral growth plates of CIA rats infused with IOPC-CD3, with this finding being consistent with immunohistochemical results showing the accumulation of T cells and iron oxide nanoparticles in the corresponding region.

CONCLUSIONS

Together with the abovementioned desirable features, these results indicate that IOPC-CD3 offers a promising prospect for a wide range of cellular and molecular MRI applications.

Low toxicity superparamagnetic magnetite nanoparticles: One-pot facile green synthesis for biological applications

Superparamagnetic magnetite nanoparticles have been synthesized by a highly reproducible polyvinyl alcohol (PVA)-based modified sol-gel process using water as the only solvent. The synthesis method has proven to be effective, time and cost saving and environmental friendly, resulting in PVA-coated magnetite nanoparticles as direct product from the synthesis, without any special atmosphere or further thermal treatment. X-ray diffraction and transmission electron microscopy revealed that the biocompatible PVA-coating prevents the nanoparticle agglomeration, giving rise to spherical crystals with sizes of 6.8nm (as-cast) and 9.5nm (heat treated) with great control over size and shape with narrow size distribution. Complementary compositional and magnetic characterizations were employed in order to study the surface chemistry and magnetic behavior of the samples, respectively. Cytotoxicity endpoints including no observed adverse effect concentration (NOAEC), 50% lethal concentration (LC50) and total lethal concentration (TLC) of the tested materials on cell viability were determined after 3, 24 and 48h of exposure. The PVA coating improved the biocompatibility of the synthesized magnetite nanoparticles showing good cell viability and low cytotoxicity effects on the MTT assay performed on BHK cells. Preliminary assessment of nanoparticles in vivo effects, performed after 48h on Balb/c mice, exposed to a range of different sub-lethal doses, showed their capacity to penetrate in liver and kidneys with no significant morphological alterations in both organs.

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.

Advances in Alzheimer's Diagnosis and Therapy: The Implications of Nanotechnology

Alzheimer's disease (AD) is a type of dementia that causes major issues for patients' memory, thinking, and behavior. Despite efforts to advance AD diagnostic and therapeutic tools, AD remains incurable due to its complex and multifactorial nature and lack of effective diagnostics/therapeutics. Nanoparticles (NPs) have demonstrated the potential to overcome the challenges and limitations associated with traditional diagnostics/therapeutics. Nanotechnology is now offering new tools and insights to advance our understanding of AD and eventually may offer new hope to AD patients. Here, we review the key roles of nanotechnologies in the recent literature, in both diagnostic and therapeutic aspects of AD, and discuss how these achievements may improve patient prognosis and quality of life.