Brain Delivery of Multifunctional Dendrimer Protein Bioconjugates

Nanoparticles in CNS Therapeutics: Pioneering Drug Delivery Advancements

INTRODUCTION

The incidence of Central Nervous System (CNS) disorders, including Parkinson's disease, Alzheimer's disease, stroke, and malignancies, has risen significantly in recent decades, contributing to millions of deaths annually. Efficacious treatment of these disorders requires medicines targeting the brain. The Blood-brain Barrier (BBB) poses a formidable challenge to effective drug delivery to the brain, hindering progress in CNS therapeutics. This review explores the latest developments in nanoparticulate carriers, highlighting their potential to overcome BBB limitations.

OBJECTIVE

This study aimed to evaluate and summarise the critical factors and pathways in the nanoparticle- based CNS targeted drug delivery.

METHODS

An extensive literature search was conducted, comprising the initial development of nanoparticle- based CNS-targeted drug delivery approaches to the latest advancements using various online search tools.

RESULTS

The properties of nanoparticles, such as type of nanoparticles, size, shape, surface charge, hydrophobicity, and surface functionalisation, along with properties of the BBB during normal and pathological conditions and their impact on the delivery of nanoparticles across the BBB, are identified and discussed here.

CONCLUSION

Important properties and pathways that determine the penetration of nanoparticles across the CNS are reviewed in this article, along with recent advances in the field.

Applications of Nanomedicine in Brain Tumor Therapy: Nanocarrierbased Drug Delivery Platforms, Challenges, and Perspectives

BACKGROUND

The most difficult kind of cancer to treat is brain cancer, which causes around 3% of all cancer-related deaths. The targeted delivery is improved with the use of technologies based on nanotechnology that are both safe and efficient. Because of this, there is now a lot of research being done on brain cancer treatments based on nanoformulations.

OBJECTIVE

In this review, the author's primary aim is to elucidate the various nanomedicine for brain cancer therapy. The authors focus primarily on the advancement of nanotechnology in treating brain cancer (BC). This review article gives readers an up-to-date look at publications on sophisticated nanosystems in treating BC, including quantum dots (QDs), nanoparticles (NPs), polymeric micelles (PMs), dendrimers, and solid lipid nanoparticles (SLNs), among others. This article offers insight into the use of various nanotechnology-based systems for therapy as well as their potential in the future. This article also emphasizes the drawbacks of nanotechnology-based methods. Future perspectives for treating brain cancer using proteomics and biomimetic nanosystems are briefly discussed.

CONCLUSION

In this review, we review several aspects of brain cancer therapy, including various nanomedicines, their challenges and future perspectives. Overall, this article gives a thorough overview of both the present state of brain cancer treatment options and the disease itself. Various patents granted for brain cancer are also discussed.

Selective Cellular Uptake and Druggability Efficacy through Functionalized Chitosan-Conjugated Polyamidoamine (PAMAM) Dendrimers

Nanotechnology has ushered in significant advancements in drug design, revolutionizing the prevention, diagnosis, and treatment of various diseases. The strategic utilization of nanotechnology to enhance drug loading, delivery, and release has garnered increasing attention, leveraging the enhanced physical and chemical properties offered by these systems. Polyamidoamine (PAMAM) dendrimers have been pivotal in drug delivery, yet there is room for further enhancement. In this study, we conjugated PAMAM dendrimers with chitosan (CS) to augment cellular internalization in tumor cells. Specifically, doxorubicin (DOX) was initially loaded into PAMAM dendrimers to form DOX-loaded PAMAM (DOX@PAMAM) complexes via intermolecular forces. Subsequently, CS was linked onto the DOX-loaded PAMAM dendrimers to yield CS-conjugated PAMAM loaded with DOX (DOX@CS@PAMAM) through glutaraldehyde crosslinking via the Schiff base reaction. The resultant DOX@CS@PAMAM complexes were comprehensively characterized using Fourier-transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), and dynamic light scattering (DLS). Notably, while the drug release profile of DOX@CS@PAMAM in acidic environments was inferior to that of DOX@PAMAM, DOX@CS@PAMAM demonstrated effective acid-responsive drug release, with a cumulative release of 70% within 25 h attributed to the imine linkage. Most importantly, DOX@CS@PAMAM exhibited significant selective cellular internalization rates and antitumor efficacy compared to DOX@PAMAM, as validated through cell viability assays, fluorescence imaging, and flow cytometry analysis. In summary, DOX@CS@PAMAM demonstrated superior antitumor effects compared to unconjugated PAMAM dendrimers, thereby broadening the scope of dendrimer-based nanomedicines with enhanced therapeutic efficacy and promising applications in cancer therapy.

Electrophoresis-Based Approach for Characterizing Dendrimer-Protein Interactions: A Proof-of-Concept Study

Improving the clinical translation of nanomedicine requires better knowledge about how nanoparticles interact with biological environments. As researchers are recognizing the importance of understanding the protein corona and characterizing how nanocarriers respond in biological systems, new tools and techniques are needed to analyze nanocarrier-protein interactions, especially for smaller size (<10 nm) nanoparticles like polyamidoamine (PAMAM) dendrimers. Here, we developed a streamlined, semiquantitative approach to assess dendrimer-protein interactions using a nondenaturing electrophoresis technique combined with mass spectrometry. With this protocol, we detect fluorescently tagged dendrimers and proteins simultaneously, enabling us to analyze when dendrimers migrate with proteins. We found that PAMAM dendrimers mostly interact with complement proteins, particularly C3 and C4a, which aligns with previously published data, verifying that our approach can be used to isolate and identify dendrimer-protein interactions.

Biomaterial strategies for regulating the neuroinflammatory response

Injury and disease in the central nervous system (CNS) can result in a dysregulated inflammatory environment that inhibits the repair of functional tissue. Biomaterials present a promising approach to tackle this complex inhibitory environment and modulate the mechanisms involved in neuroinflammation to halt the progression of secondary injury and promote the repair of functional tissue. In this review, we will cover recent advances in biomaterial strategies, including nanoparticles, hydrogels, implantable scaffolds, and neural probe coatings, that have been used to modulate the innate immune response to injury and disease within the CNS. The stages of inflammation following CNS injury and the main inflammatory contributors involved in common neurodegenerative diseases will be discussed, as understanding the inflammatory response to injury and disease is critical for identifying therapeutic targets and designing effective biomaterial-based treatment strategies. Biomaterials and novel composites will then be discussed with an emphasis on strategies that deliver immunomodulatory agents or utilize cell-material interactions to modulate inflammation and promote functional tissue repair. We will explore the application of these biomaterial-based strategies in the context of nanoparticle- and hydrogel-mediated delivery of small molecule drugs and therapeutic proteins to inflamed nervous tissue, implantation of hydrogels and scaffolds to modulate immune cell behavior and guide axon elongation, and neural probe coatings to mitigate glial scarring and enhance signaling at the tissue-device interface. Finally, we will present a future outlook on the growing role of biomaterial-based strategies for immunomodulation in regenerative medicine and neuroengineering applications in the CNS.

Therapeutic Supramolecular Polymers: Designs and Applications

The self-assembly of low-molecular-weight building motifs into supramolecular polymers has unlocked a new realm of materials with distinct properties and tremendous potential for advancing medical practices. Leveraging the reversible and dynamic nature of non-covalent interactions, these supramolecular polymers exhibit inherent responsiveness to their microenvironment, physiological cues, and biomolecular signals, making them uniquely suited for diverse biomedical applications. In this review, we intend to explore the principles of design, synthesis methodologies, and strategic developments that underlie the creation of supramolecular polymers as carriers for therapeutics, contributing to the treatment and prevention of a spectrum of human diseases. We delve into the principles underlying monomer design, emphasizing the pivotal role of non-covalent interactions, directionality, and reversibility. Moreover, we explore the intricate balance between thermodynamics and kinetics in supramolecular polymerization, illuminating strategies for achieving controlled sizes and distributions. Categorically, we examine their exciting biomedical applications: individual polymers as discrete carriers for therapeutics, delving into their interactions with cells, and in vivo dynamics; and supramolecular polymeric hydrogels as injectable depots, with a focus on their roles in cancer immunotherapy, sustained drug release, and regenerative medicine. As the field continues to burgeon, harnessing the unique attributes of therapeutic supramolecular polymers holds the promise of transformative impacts across the biomedical landscape.

Trends on Novel Targets and Nanotechnology-Based Drug Delivery System in the Treatment of Parkinson's disease: Recent Advancement in Drug Development

Parkinson's disease (PD) is a progressive neurodegenerative disorder that impacts a significant portion of the population. Despite extensive research, an effective cure for PD remains elusive, and conventional pharmacological treatments often face limitations in efficacy and management of symptoms. There has been a lot of discussion about using nanotechnology to increase the bioavailability of small- molecule drugs to target cells in recent years. It is possible that PD treatment might become far more effective and have fewer side effects if medication delivery mechanisms were to be improved. Potential alternatives to pharmacological therapy for molecular imaging and treatment of PD may lie in abnormal proteins such as parkin, α-synuclein, leucine-rich repeat serine and threonine protein kinase 2. Published research has demonstrated encouraging outcomes when nanomedicine-based approaches are used to address the challenges of PD therapy. So, to address the present difficulties of antiparkinsonian treatment, this review outlines the key issues and limitations of antiparkinsonian medications, new therapeutic strategies, and the breadth of delivery based on nanomedicine. This review covers a wide range of subjects, including drug distribution in the brain, the efficacy of drug-loaded nano-carriers in crossing the blood-brain barrier, and their release profiles. In PD, the nano-carriers are also used. Novel techniques of pharmaceutical delivery are currently made possible by vesicular carriers, which eliminate the requirement to cross the blood-brain barrier (BBB).

The application advances of dendrimers in biomedical field

Dendrimers are a family of nano‐sized three‐dimensional polymers with unique dendritic branching structures and compact spherical geometries. In recent years, dendrimers have made a series of breakthroughs in the biomedical field. In this review, we introduce the synthesis principles, modification methods, and new materials designed based on dendrimers; discuss the importance of cytotoxicity of dendrimers for applications; and elaborate on their applications in the field of molecular assembly and cancer diagnosis and treatment. We speculate that in the near future, more new materials based on dendrimers will be applied in the biomedical field.

Emerging strategies to fabricate polymeric nanocarriers for enhanced drug delivery across blood-brain barrier: An overview

Blood-brain barrier (BBB) serves as an essential interface between central nervous system (CNS) and its periphery, allowing selective permeation of ions, gaseous molecules, and other nutrients to maintain metabolic functions of brain. Concurrently, it restricts passage of unsolicited materials from bloodstream to CNS which could otherwise lead to neurotoxicity. Nevertheless, in the treatment of neurodegenerative diseases such as Parkinson's, Alzheimer's, diffuse intrinsic pontine glioma, and other brain cancers, drugs must reach CNS. Among various materials developed for this purpose, a few judiciously selected polymeric nanocarriers are reported to be highly prospective to facilitate BBB permeation. However, the challenge of transporting drug-loaded nanomaterials across this barrier remains formidable. Herein a concise analysis of recently employed strategies for designing polymeric nanocarriers to deliver therapeutics across BBB is presented. Impacts of 3Ss, namely, size, shape, and surface charge of polymeric nanocarriers on BBB permeation along with different ligands used for nanoparticle surface modification to achieve targeted delivery have been scrutinized. Finally, we elucidated future research directions in the context of designing smart polymeric nanocarriers for BBB permeation. This work aims to guide researchers engaged in polymeric nanocarrier design, helping them navigate where to begin, what challenges to address, and how to proceed effectively.

Influence factors on and potential strategies to amplify receptor-mediated nanodrug delivery across the blood-brain barrier

INTRODUCTION

A major challenge in treating central nervous system (CNS) disorders is to achieve adequate drug delivery across the blood-brain barrier (BBB). Receptor-mediated nanodrug delivery as a Trojan horse strategy has become an exciting approach. However, these nanodrugs do not accumulate significantly in the brain parenchyma, which greatly limits the therapeutic effect of drugs. Amplifying the efficiency of receptor-mediated nanodrug delivery across the BBB becomes the holy grail in the treatment of CNS disorders.

AREAS COVERED

In this review, we tend to establish links between dynamic BBB and receptor-mediated nanodrug delivery, starting with the delivery processes across the BBB, describing factors affecting nanodrug delivery efficiency, and summarizing potential strategies that may amplify delivery efficiency.

EXPERT OPINION

Receptor-mediated nanodrug delivery is a common approach to significantly enhance the efficiency of brain-targeting delivery. As BBB is constantly undergoing changes, it is essential to investigate the impact of diseases on the effectiveness of brain-targeting nanodrug delivery. More critically, there are several barriers to achieving brain-targeting nanodrug delivery in the five stages of receptor-mediated transcytosis (RMT), and the impacts can be conflicting, requiring intricate balance. Further studies are also needed to investigate the material toxicity of nanodrugs to address the issue of clinical translation.

Nanoparticle Strategies to Improve the Delivery of Anticancer Drugs across the Blood-Brain Barrier to Treat Brain Tumors

Primary brain and central nervous system (CNS) tumors are a diverse group of neoplasms that occur within the brain and spinal cord. Although significant advances in our understanding of the intricate biological underpinnings of CNS neoplasm tumorigenesis and progression have been made, the translation of these discoveries into effective therapies has been stymied by the unique challenges presented by these tumors' exquisitely sensitive location and the body's own defense mechanisms (e.g., the brain-CSF barrier and blood-brain barrier), which normally protect the CNS from toxic insult. These barriers effectively prevent the delivery of therapeutics to the site of disease. To overcome these obstacles, new methods for therapeutic delivery are being developed, with one such approach being the utilization of nanoparticles. Here, we will cover the current state of the field with a particular focus on the challenges posed by the BBB, the different nanoparticle classes which are under development for targeted CNS tumor therapeutics delivery, and strategies which have been developed to bypass the BBB and enable effective therapeutics delivery to the site of disease.

Role of microglia autophagy and mitophagy in age-related neurodegenerative diseases

Microglia, characterized by responding to damage, regulating the secretion of soluble inflammatory mediators, and engulfing specific segments in the central nervous system (CNS), function as key immune cells in the CNS. Emerging evidence suggests that microglia coordinate the inflammatory responses in CNS system and play a pivotal role in the pathogenesis of age-related neurodegenerative diseases (NDDs). Remarkably, microglia autophagy participates in the regulation of subcellular substances, which includes the degradation of misfolded proteins and other harmful constituents produced by neurons. Therefore, microglia autophagy regulates neuronal homeostasis maintenance and process of neuroinflammation. In this review, we aimed at highlighting the pivotal role of microglia autophagy in the pathogenesis of age-related NDDs. Besides the mechanistic process and the co-interaction between microglia autophagy and different kinds of NDDs, we also emphasized potential therapeutic agents and approaches that could be utilized at the onset and progression of these diseases through modulating microglia autophagy, including promising nanomedicines. Our review provides a valuable reference for subsequent studies focusing on treatments of neurodegenerative disorders. The exploration of microglia autophagy and the development of nanomedicines greatly enhances current understanding of NDDs.

Neuro-nanotechnology: diagnostic and therapeutic nano-based strategies in applied neuroscience

Artificial, de-novo manufactured materials (with controlled nano-sized characteristics) have been progressively used by neuroscientists during the last several decades. The introduction of novel implantable bioelectronics interfaces that are better suited to their biological targets is one example of an innovation that has emerged as a result of advanced nanostructures and implantable bioelectronics interfaces, which has increased the potential of prostheses and neural interfaces. The unique physical-chemical properties of nanoparticles have also facilitated the development of novel imaging instruments for advanced laboratory systems, as well as intelligently manufactured scaffolds and microelectrodes and other technologies designed to increase our understanding of neural tissue processes. The incorporation of nanotechnology into physiology and cell biology enables the tailoring of molecular interactions. This involves unique interactions with neurons and glial cells in neuroscience. Technology solutions intended to effectively interact with neuronal cells, improved molecular-based diagnostic techniques, biomaterials and hybridized compounds utilized for neural regeneration, neuroprotection, and targeted delivery of medicines as well as small chemicals across the blood-brain barrier are all purposes of the present article.

Nanodelivery of antiretroviral drugs to nervous tissues

Despite the development of effective combined antiretroviral therapy (cART), the neurocognitive impairments associated with human immunodeficiency virus (HIV) remain challenging. The presence of the blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCFB) impedes the adequate penetration of certain antiretroviral drugs into the brain. In addition, reports have shown that some antiretroviral drugs cause neurotoxicity resulting from their interaction with nervous tissues due to long-term systemic exposure. Therefore, the research into the effective therapeutic modality that would cater for the HIV-associated neurocognitive disorders (HAND) and ART toxicity is now receiving broad research attention. Thus, this review explores the latest information in managing HAND using a nanoparticle drug delivery system (NDDS). We discussed the neurotoxicity profile of various approved ART. Also, we explained the applications of silver nanoparticles (AgNPs) in medicine, their different synthesis methods and their interaction with nervous tissues. Lastly, while proposing AgNPs as useful nanoparticles in properly delivering ART to enhance effectiveness and minimize neurocognitive disorders, we hypothesize that the perceived toxicity of AgNPs could be minimized by taking appropriate precautions. One such precaution is using appropriate reducing and stabilizing agents such as trisodium citrate to reduce silver ion Ag + to ground state Ag0 during the synthesis. Also, the usage of medium-sized, spherical-shaped AgNPs is encouraged in AgNPs-based drug delivery to the brain due to their ability to deliver therapeutic agents across BBB. In addition, characterization and functionalization of the synthesized AgNPs are required during the drug delivery approach. Putting all these factors in place would minimize toxicity and enhance the usage of AgNPs in delivering therapeutic agents across the BBB to the targeted brain tissue and could cater for the HIV-associated neurocognitive disorders and neurotoxic effects of antiretroviral drugs (ARDs).

Polymeric Dendrimers as Nanocarrier Vectors for Neurotheranostics

Dendrimers are polymers with well-defined 3D branched structures that are vastly utilized in various neurotheranostics and biomedical applications, particularly as nanocarrier vectors. Imaging agents can be loaded into dendrimers to improve the accuracy of diagnostic imaging processes. Likewise, combining pharmaceutical agents and anticancer drugs with dendrimers can enhance their solubility, biocompatibility, and efficiency. Practically, by modifying ligands on the surface of dendrimers, effective therapeutic and diagnostic platforms can be constructed and implemented for targeted delivery. Dendrimer-based nanocarriers also show great potential in gene delivery. Since enzymes can degrade genetic materials during their blood circulation, dendrimers exhibit promising packaging and delivery alternatives, particularly for central nervous system (CNS) treatments. The DNA and RNA encapsulated in dendrimers represented by polyamidoamine that are used for targeted brain delivery, via chemical-structural adjustments and appropriate generation, significantly improve the correlation between transfection efficiency and cytotoxicity. This article reports a comprehensive review of dendrimers' structures, synthesis processes, and biological applications. Recent progress in diagnostic imaging processes and therapeutic applications for cancers and other CNS diseases are presented. Potential challenges and future directions in the development of dendrimers, which provide the theoretical basis for their broader applications in healthcare, are also discussed.

Polymeric Nanoparticles in Brain Cancer Therapy: A Review of Current Approaches

Translation of novel therapies for brain cancer into clinical practice is of the utmost importance as primary brain tumors are responsible for more than 200,000 deaths worldwide each year. While many research efforts have been aimed at improving survival rates over the years, prognosis for patients with glioblastoma and other primary brain tumors remains poor. Safely delivering chemotherapeutic drugs and other anti-cancer compounds across the blood-brain barrier and directly to tumor cells is perhaps the greatest challenge in treating brain cancer. Polymeric nanoparticles (NPs) are powerful, highly tunable carrier systems that may be able to overcome those obstacles. Several studies have shown appropriately-constructed polymeric NPs cross the blood-brain barrier, increase drug bioavailability, reduce systemic toxicity, and selectively target central nervous system cancer cells. While no studies relating to their use in treating brain cancer are in clinical trials, there is mounting preclinical evidence that polymeric NPs could be beneficial for brain tumor therapy. This review includes a variety of polymeric NPs and how their associated composition, surface modifications, and method of delivery impact their capacity to improve brain tumor therapy.

"Cascaded Rocket" Nanosystems with Spatiotemporal Separation for Triple-Synergistic Therapy of Alzheimer's Disease

Alzheimer's disease (AD) remains an incurable disease due to the intricate pathogenesis. The neuropathological hallmarks include extracellular amyloid-β (Aβ) plaques, tau phosphorylation and extensive oxidative stress in neurons, which facilitate the progression of AD. Based on the complex etiology, a spatiotemporally "cascaded rocket" delivery system (DPH/TPGAS NPs) with metal ion/enzyme responses is established in this study for triple-synergistic AD treatment. After targeting and permeating the blood-brain barrier (BBB), the histidine units in the DPH chelate excess metal ions at the extracellular microenvironment, restraining the formation of Aβ aggregates, inducing the first-stage separation. Then, the remanent system targets neuronal cells and triggers the second separation with cathepsin B for reducing the level of phosphorylated tau and oxidative stress. Accordingly, the DPH/TPGAS NPs can achieve spatiotemporal drug release, which results in enhanced synergistic therapeutic effects both in the extracellular and intracellular region of the AD brain. After treating with DPH/TPGAS NPs, the memory deficits, levels of Aβ and phosphorylated tau, inflammation and neuron damages are remarkably ameliorated in 3 × Tg-AD mice. Therefore, this "cascaded rocket" delivery system has great potential to serve as a powerful platform and provides a new horizon to the therapeutic strategy for AD and other brain diseases' treatments.

Dendrimers as Antiamyloid Agents

Dendrimer-protein conjugates have significant prospects for biological applications. The complexation changes the biophysical behavior of both proteins and dendrimers. The dendrimers could influence the secondary structure of proteins, zeta-potential, distribution of charged regions on the surface, the protein-protein interactions, etc. These changes offer significant possibilities for the application of these features in nanotheranostics and biomedicine. Based on the dendrimer-protein interactions, several therapeutic applications of dendrimers have emerged. Thus, the formation of stable complexes retains the disordered proteins on the aggregation, which is especially important in neurodegenerative diseases. To clarify the origin of these properties and assess the efficiency of action, the mechanism of protein-dendrimer interaction and the nature and driving force of binding are considered in this review. The review outlines the antiamyloid activity of dendrimers and discusses the effect of dendrimer structures and external factors on their antiamyloid properties.

Polymeric Nanoparticles Properties and Brain Delivery

Safe and reliable entry to the brain is essential for successful diagnosis and treatment of diseases, but it still poses major challenges. As a result, many therapeutic approaches to treating disorders associated with the central nervous system (CNS) still only show limited success. Nano-sized systems are being explored as drug carriers and show great improvements in the delivery of many therapeutics. The systemic delivery of nanoparticles (NPs) or nanocarriers (NCs) to the brain involves reaching the neurovascular unit (NVU), being transported across the blood-brain barrier, (BBB) and accumulating in the brain. Each of these steps can benefit from specifically controlled properties of NPs. Here, we discuss how brain delivery by NPs can benefit from careful design of the NP properties. Properties such as size, charge, shape, and ligand functionalization are commonly addressed in the literature; however, properties such as ligand density, linker length, avidity, protein corona, and stiffness are insufficiently discussed. This is unfortunate since they present great value against multiple barriers encountered by the NPs before reaching the brain, particularly the BBB. We further highlight important examples utilizing targeting ligands and how functionalization parameters, e.g., ligand density and ligand properties, can affect the success of the nano-based delivery system.

Understanding the Potential of Genome Editing in Parkinson's Disease

CRISPR is a simple and cost-efficient gene-editing technique that has become increasingly popular over the last decades. Various CRISPR/Cas-based applications have been developed to introduce changes in the genome and alter gene expression in diverse systems and tissues. These novel gene-editing techniques are particularly promising for investigating and treating neurodegenerative diseases, including Parkinson's disease, for which we currently lack efficient disease-modifying treatment options. Gene therapy could thus provide treatment alternatives, revolutionizing our ability to treat this disease. Here, we review our current knowledge on the genetic basis of Parkinson's disease to highlight the main biological pathways that become disrupted in Parkinson's disease and their potential as gene therapy targets. Next, we perform a comprehensive review of novel delivery vehicles available for gene-editing applications, critical for their successful application in both innovative research and potential therapies. Finally, we review the latest developments in CRISPR-based applications and gene therapies to understand and treat Parkinson's disease. We carefully examine their advantages and shortcomings for diverse gene-editing applications in the brain, highlighting promising avenues for future research.

Rationally Designed Galactose Dendrimer for Hepatocyte-Specific Targeting and Intracellular Drug Delivery for the Treatment of Liver Disorders

Over two million people die of liver disorders every year globally. Hepatocytes are the key cells affected in several acute and chronic liver diseases. The current clinical outcomes of liver-targeted nanoparticles are limited, necessitating the need to develop smart hepatocyte-targeted drug delivery systems. Here, we present the rational design and development of a hepatocyte-targeting glycodendrimer (GAL-24) built from biocompatible building blocks, using expedite and facile chemical methodology. GAL-24 is designed to inherently target asialoglycoprotein receptor 1 (ASGP-R) on hepatocytes and shows significant accumulation in the liver (20% of injected dose), just 1 h after systemic administration. This is highly specific to hepatocytes, with over 80% of hepatocytes showing GAL-24-Cy5 signal at 24 h. GAL-24-Cy5 maintains hepatocyte-targeting capabilities in both a mouse model of severe acetaminophen poisoning-induced hepatic necrosis and a rat model of nonalcoholic steatohepatitis (NASH). This GAL-24 nanoplatform holds great promise for improved drug delivery to hepatocytes to combat many liver disorders.

Early administration of MPC-n(IVIg) selectively accumulates in ischemic areas to protect inflammation-induced brain damage from ischemic stroke

Ischemic stroke is an acute and severe neurological disease, which leads to disability and death. Immunomodulatory therapies exert multiple remarkable protective effects during ischemic stroke. However, patients suffering from ischemic stroke do not benefit from immunomodulatory therapies due to the presence of the blood-brain barrier (BBB) and their off-target effects. Methods: We presented a delivery strategy to optimize immunomodulatory therapies by facilitating BBB penetration and selectively delivering intravenous immunoglobulin (IVIg) to ischemic regions using 2-methacryloyloxyethyl phosphorylcholine (MPC)-nanocapsules, MPC-n(IVIg), synthesized using MPC monomers and ethylene glycol dimethyl acrylate (EGDMA) crosslinker via in situ polymerization. In vitro and in vivo experiments verify the effect and safety of MPC-n(IVIg). Results: MPC-n(IVIg) efficiently crosses the BBB and IVIg selectively accumulates in ischemic areas in a high-affinity choline transporter 1 (ChT1)-overexpression dependent manner via endothelial cells in ischemic areas. Moreover, earlier administration of MPC-n(IVIg) more efficiently deliver IVIg to ischemic areas. Furthermore, the early administration of low-dosage MPC-n(IVIg) decreases neurological deficits and mortality by suppressing stroke-induced inflammation in the middle cerebral artery occlusion model. Conclusion: Our findings indicate a promising strategy to efficiently deliver the therapeutics to the ischemic target brain tissue and lower the effective dose of therapeutic drugs for treating ischemic strokes.

Current Status of Brain Tumor in the Kingdom of Saudi Arabia and Application of Nanobiotechnology for Its Treatment: A Comprehensive Review

OBJECTIVE

Brain tumors are the most challenging of all tumors and accounts for about 3% of all cancer allied deaths. The aim of the present review is to examine the brain tumor prevalence and treatment modalities available in the Kingdom of Saudi Arabia. It also provides a comprehensive analysis of the application of various nanotechnology-based products for brain cancer treatments along with their prospective future advancements.

METHODS

A literature review was performed to identify and summarize the current status of brain cancer in Saudi Arabia and the scope of nanobiotechnology in its treatment.

RESULTS

Depending upon the study population data analysis, gliomas, astrocytoma, meningioma, and metastatic cancer have a higher incidence rate in Saudi Arabia than in other countries, and are mostly treated in accordance with conventional treatment modalities for brain cancer. Due to the poor prognosis of cancer, it has an average survival rate of 2 years. Conventional therapy includes surgery, radiotherapy, chemotherapy, and a combination thereof, but these do not control the disease's recurrence. Among the various nanomaterials discussed, liposomes and polymeric nanoformulations have demonstrated encouraging outcomes for facilitated brain cancer treatment.

CONCLUSIONS

Nanomaterials possess the capacity to overcome the shortcomings of conventional therapies. Polymer-based nanomaterials have shown encouraging outcomes against brain cancer when amalgamated with other nano-based therapies. Nonetheless, nanomaterials could be devised that possess minimal toxicity towards normal cells or that specifically target tumor cells. In addition, rigorous clinical investigations are warranted to prepare them as an efficient and safe modality for brain cancer therapy.

Development of Polymeric Nanoparticles for Blood-Brain Barrier Transfer-Strategies and Challenges

Neurological disorders such as Alzheimer's disease, stroke, and brain cancers are difficult to treat with current drugs as their delivery efficacy to the brain is severely hampered by the presence of the blood-brain barrier (BBB). Drug delivery systems have been extensively explored in recent decades aiming to circumvent this barrier. In particular, polymeric nanoparticles have shown enormous potentials owing to their unique properties, such as high tunability, ease of synthesis, and control over drug release profile. However, careful analysis of their performance in effective drug transport across the BBB should be performed using clinically relevant testing models. In this review, polymeric nanoparticle systems for drug delivery to the central nervous system are discussed with an emphasis on the effects of particle size, shape, and surface modifications on BBB penetration. Moreover, the authors critically analyze the current in vitro and in vivo models used to evaluate BBB penetration efficacy, including the latest developments in the BBB-on-a-chip models. Finally, the challenges and future perspectives for the development of polymeric nanoparticles to combat neurological disorders are discussed.

Controlled Growth of Dendrimer-Coated Gold Nanoparticles: A Solvent-Free Process in Mild Conditions

Monodisperse dendrimer-coated gold nanoparticles with a spherical shape have been obtained by direct reduction of HAuCl4 with sodium borohydride in the presence of dodecanethiol as a stabilizer and subsequent functionalization by ligand exchange reaction with polybenzylic thiolated dendrons. The substitution pattern of the dendrimeric units plays a fundamental role in the rate of the functionalization exchange process and consequently conditions the size and the polydispersity of the NPs obtained. An ulterior growth process occurs by thermal stimuli (150 °C) in a solvent-free environment. This method, carried out in mild conditions, allows the formation of highly monodisperse gold NPs with different sizes for different time reactions, and we discuss the mechanisms involved in this process. Finally, we demonstrate the chemical composition and stability of our compounds by structural, thermal, and chemical characterization of the samples before and after thermal treatment.

The membrane axis of Alzheimer's nanomedicine

Alzheimer's disease (AD) is a major neurological disorder impairing its carrier's cognitive function, memory and lifespan. While the development of AD nanomedicine is still nascent, the field is evolving into a new scientific frontier driven by the diverse physicochemical properties and theranostic potential of nanomaterials and nanocomposites. Characteristic to the AD pathology is the deposition of amyloid plaques and tangles of amyloid beta (Aβ) and tau, whose aggregation kinetics may be curbed by nanoparticle inhibitors via sequence-specific targeting or nonspecific interactions with the amyloidogenic proteins. As literature implicates cell membrane as a culprit in AD pathogenesis, here we summarize the membrane axis of AD nanomedicine and present a new rationale that the field development may greatly benefit from harnessing our existing knowledge of Aβ-membrane interaction, nanoparticle-membrane interaction and Aβ-nanoparticle interaction.

The Inclusion of a Matrix Metalloproteinase-9 Responsive Sequence in Self-assembled Peptide-based Brain-Targeting Nanoparticles Improves the Efficiency of Nanoparticles Crossing the Blood-Brain Barrier at Elevated MMP-9 Levels

This study investigated whether the inclusion of a matrix metalloproteinase-9 (MMP-9) responsive sequence in self-assembled peptide-based brain-targeting nanoparticles (NPs) would enhance the blood-brain barrier (BBB) penetration when MMP-9 levels are elevated both in the brain and blood circulation. Brain-targeting peptides were conjugated at the N-terminus to MMP-9-responsive peptides, and these were conjugated at the N-terminus to lipid moiety (cholesteryl chloroformate or palmitic acid). Two constructs did not have MMP-9-responsive peptides. NPs were characterised for size, charge, critical micelle concentration, toxicity, blood compatibility, neural cell uptake, release profiles, and in vitro BBB permeability simulating normal or elevated MMP-9 levels. The inclusion of MMP-9-sensitive sequences did not improve the release of a model drug in the presence of active MMP-9 from NPs compared to distilled water. ¹⁹F NMR studies suggested the burial of MMP-9-sensitive sequences inside the NPs making them inaccessible to MMP-9. Only cholesterol-GGGCKAPETALC (responsive to MMP-9) NPs showed <5% haemolysis, <1 pg/mL release of IL-1β at 500 μg/mL from THP1 cells, with 70.75 ± 5.78% of NPs crossing the BBB at 24 h in presence of active MMP-9. In conclusion, brain-targeting NPs showed higher transport across the BBB model when MMP-9 levels were elevated and the brain-targeting ligand was responsive to MMP-9.

Dual-responsive mesoporous silica nanoparticles coated with carbon dots and polymers for drug encapsulation and delivery

Aim: Smart mesoporous silica nanoparticles (MSNs) coated with carbon dots (CDs) and poly(N-vinylcaprolactam) (PNVCL) as a mixed shell (CDs/PNVCL polymer grafted MSNs) were prepared for pH-trigged anticancer drug release and real-time monitoring. Materials & methods: The amino-terminated PNVCL and amino-rich CDs were grafted onto the surface of aldehyde group functionalized MSNs through Schiff base reaction. Doxorubicin (DOX) was loaded into the prepared nanoparticles. Results: DOX could be quickly released in the tumor environment, leading to cell apoptosis. The linear fit between the percentage of released DOX and the fluorescence intensity of CDs indicated that the change in fluorescence intensity could be used to monitor drug release in real time. Conclusion: The as-prepared CDs/PNVCL polymer grafted MSNs are promising candidates for integrating controllable release and real-time monitoring in cancer treatment.

Combination of Alanine and Glutathione as Targeting Ligands of Nanoparticles Enhances Cargo Delivery into the Cells of the Neurovascular Unit

Inefficient drug delivery across the blood–brain barrier (BBB) and into target cells in the brain hinders the treatment of neurological diseases. One strategy to increase the brain penetration of drugs is to use vesicular nanoparticles functionalized with multiple ligands of BBB transporters as vehicles. Once within the brain, however, drugs must also be able to reach their therapeutic targets in the different cell types. It is, therefore, favorable if such nanocarriers are designed that can deliver their cargo not only to brain endothelial cells, but to other cell types as well. Here, we show that alanine-glutathione dual-targeting of niosomes enhances the delivery of a large protein cargo into cultured cells of the neurovascular unit, namely brain endothelial cells, pericytes, astrocytes and neurons. Furthermore, using metabolic and endocytic inhibitors, we show that the cellular uptake of niosomes is energy-dependent and is partially mediated by endocytosis. Finally, we demonstate the ability of our targeted nanovesicles to deliver their cargo into astroglial cells after crossing the BBB in vitro. These data indicate that dual-labeling of nanoparticles with alanine and glutathione can potentially be exploited to deliver drugs, even biopharmacons, across the BBB and into multiple cell types in the brain.

Breaking Barriers: Bioinspired Strategies for Targeted Neuronal Delivery to the Central Nervous System

Central nervous system (CNS) disorders encompass a vast spectrum of pathological conditions and represent a growing concern worldwide. Despite the high social and clinical interest in trying to solve these pathologies, there are many challenges to bridge in order to achieve an effective therapy. One of the main obstacles to advancements in this field that has hampered many of the therapeutic strategies proposed to date is the presence of the CNS barriers that restrict the access to the brain. However, adequate brain biodistribution and neuronal cells specific accumulation in the targeted site also represent major hurdles to the attainment of a successful CNS treatment. Over the last few years, nanotechnology has taken a step forward towards the development of therapeutics in neurologic diseases and different approaches have been developed to surpass these obstacles. The versatility of the designed nanocarriers in terms of physical and chemical properties, and the possibility to functionalize them with specific moieties, have resulted in improved neurotargeted delivery profiles. With the concomitant progress in biology research, many of these strategies have been inspired by nature and have taken advantage of physiological processes to achieve brain delivery. Here, the different nanosystems and targeting moieties used to achieve a neuronal delivery reported in the open literature are comprehensively reviewed and critically discussed, with emphasis on the most recent bioinspired advances in the field. Finally, we express our view on the paramount challenges in targeted neuronal delivery that need to be overcome for these promising therapeutics to move from the bench to the bedside.

Routing Nanomolar Protein Cargoes to Lipid Raft-Mediated/Caveolar Endocytosis through a Ganglioside GM1-Specific Recognition Tag

There is a pressing need to develop ways to deliver therapeutic macromolecules to their intracellular targets. Certain viral and bacterial proteins are readily internalized in functional form through lipid raft-mediated/caveolar endocytosis, but mimicking this process with protein cargoes at therapeutically relevant concentrations is a great challenge. Targeting ganglioside GM1 in the caveolar pits triggers endocytosis. A pentapeptide sequence WYKYW is presented, which specifically captures the glycan moiety of GM1 (K D = 24 nm). The WYKYW-tag facilitates the GM1-dependent endocytosis of proteins in which the cargo-loaded caveosomes do not fuse with lysosomes. A structurally intact immunoglobulin G complex (580 kDa) is successfully delivered into live HeLa cells at extracellular concentrations ranging from 20 to 160 nm, and escape of the cargo proteins to the cytosol is observed. The short peptidic WYKYW-tag is an advantageous endocytosis routing sequence for lipid raft-mediated/caveolar cell delivery of therapeutic macromolecules, especially for cancer cells that overexpress GM1.

An "Amyloid-β Cleaner" for the Treatment of Alzheimer's Disease by Normalizing Microglial Dysfunction

Alzheimer's disease (AD) is a devastating neurodegenerative disorder characterized by progressive cognitive and memory loss. The vicious circle between dysfunctional microglia and amyloid-β (Aβ) is a crucial pathological event and accelerates the progression of AD. Herein, a zwitterionic poly(carboxybetaine) (PCB)-based nanoparticle (MCPZFS NP) with normalizing the dysfunctional microglia and Aβ recruitment is established for the treatment of AD. Compared with the neural polyethylene glycol (PEG)-based nanoparticles (MEPZFS NPs), the MCPZFS NPs significantly alleviate the priming of microglia by decreasing the level of proinflammatory mediators and promoting the secretion of BDNF. Most importantly, quite different from PEG, the PCB-based NPs exhibit the behavior to recruit Aβ into microglia, which significantly enhances the Aβ phagocytosis. Moreover, the Aβ degradation is changed from the conventional lysosomal/autophagy to the proteasomal pathway in the presence of MCPZFS NPs. After the treatment with MCPZFS NPs, the Aβ burden, neuron damages, memory deficits, and neuroinflammation of APPswe/PS1dE9 mice are significantly attenuated in the brain. Therefore, the PCB-based MCPZFS NPs have great potential to serve as an "Aβ cleaner" and provide a new insight into the therapeutic strategy for AD therapy.

Development of a hybrid nanocarrier-recognizing tumor vasculature and penetrating the BBB for glioblastoma multi-targeting therapy

The success of glioma chemotherapy is hampered by poor drug penetration ability across the blood-brain barrier (BBB) and low intratumoral drug concentration. Novel tumor-targeted delivery systems are useful in specifically accumulating in the tumor foci and penetrating into the glioma core after entering into the brain. Here we show that a multi-targeting hybrid nanocarrier (Pep-MLHA HNPs) system based on hyaluronic acid (HA)-modified polymer and a functional peptide possesses multi-target capability and stronger penetration ability into the core of three-dimensional tumor spheroids, could migrate efficiently across the BBB in vitro. The intensity of the Pep-MLHA HNPs after transporting across the BBB was 5.2-fold and 5.6-fold higher than that of ML NPs in C6 and U87 cells, respectively. More interestingly, this multi-targeting hybrid system displayed high colloidal stability in PBS solution, and weak negative zeta potential (-1.99 ± 0.655 mV) minimizing nonspecific interactions with plasma proteins and promoting long-term circulation in vivo. Additionally, the multi-targeting hybrid system induced enhanced tumor localization in U87 in situ-bearing nude mice and xenograft-bearing nude mice after systemic administration. Furthermore, docetaxel (DTX)-loaded Pep-MLHA HNPs showed negligible systemic toxicity and enhanced therapeutic efficacy, with significantly improved survival rates in intracranial C6 glioma-bearing rats. The 50% survival rate of DTX/Pep-MLHA HNPs-treated rats (40 days) was significantly longer than that of rats treated with NS (22 days), Taxotere® (25 days), DTX/ML NPs (25 days), DTX/Pep NPs (32 days) and DTX/MLHA NPs (29 days). All the results suggested that the multi-targeting hybrid nanocarrier system is promising for glioma treatment.

Dendrimer-Based Drug Delivery Systems for Brain Targeting

Human neuroscience has made remarkable progress in understanding basic aspects of functional organization; it is a renowned fact that the blood-brain barrier (BBB) impedes the permeation and access of most drugs to central nervous system (CNS) and that many neurological diseases remain undertreated. Therefore, a number of nanocarriers have been designed over the past few decades to deliver drugs to the brain. Among these nanomaterials, dendrimers have procured an enormous attention from scholars because of their nanoscale uniform size, ease of multi-functionalization, and available internal cavities. As hyper-branched 3D macromolecules, dendrimers can be maneuvered to transport diverse therapeutic agents, incorporating small molecules, peptides, and genes; diminishing their cytotoxicity; and improving their efficacy. Herein, the present review will give exhaustive details of extensive researches in the field of dendrimer-based vehicles to deliver drugs through the BBB in a secure and effectual manner. It is also a souvenir in commemorating Donald A. Tomalia on his 80th birthday.

Unraveling In Vivo Brain Transport of Protein-Coated Fluorescent Nanodiamonds

Nanotheranostics, combining diagnostics and therapy, has the potential to revolutionize treatment of neurological disorders. But one of the major obstacles for treating central nervous system diseases is the blood-brain barrier (BBB) preventing systemic delivery of drugs and optical probes into the brain. To overcome these limitations, nanodiamonds (NDs) are investigated in this study as they are a powerful sensing and imaging platform for various biological applications and possess outstanding stable far-red fluorescence, do not photobleach, and are highly biocompatible. Herein, fluorescent NDs encapsulated by a customized human serum albumin-based biopolymer (polyethylene glycol) coating (dcHSA-PEG) are taken up by target brain cells. In vitro BBB models reveal transcytosis and an additional direct cell-cell transport via tunneling nanotubes. Systemic application of dcHSA-NDs confirms their ability to cross the BBB in a mouse model. Tracking of dcHSA-NDs is possible at the single cell level and reveals their uptake into neurons and astrocytes in vivo. This study shows for the first time systemic NDs brain delivery and suggests transport mechanisms across the BBB and direct cell-cell transport. Fluorescent NDs are envisioned as traceable transporters for in vivo brain imaging, sensing, and drug delivery.

Supramolecular Toxin Complexes for Targeted Pharmacological Modulation of Polymorphonuclear Leukocyte Functions

The targeted pharmacological modulation of polymorphonuclear leukocytes (PMNs) is of major medical interest. These innate immune cells play a central role in the defense against pathogenic microorganisms. However, their excessive chemotactic recruitment into tissues after traumatic injury is detrimental due to local and systemic inflammation. Rho-GTPases, being the master regulators of the actin cytoskeleton, regulate migration and chemotaxis of PMNs, are attractive pharmacological targets. Herein, supramolecular protein complexes are assembled in a "mix-and-match" approach containing the specific Rho-inhibiting clostridial C3 enzyme and three PMN-binding peptides using an avidin platform. Selective delivery of the C3 Rho-inhibitor with these complexes into the cytosol of human neutrophil-like NB-4 cells and primary human PMNs ex vivo is demonstrated, where they catalyze the adenosine diphosphate (ADP) ribosylation of Rho and induce a characteristic change in cell morphology. Notably, the complexes do not deliver C3 enzyme into human lung epithelial cells, A549 lung cancer cells, and immortalized human alveolar epithelial cells (hAELVi), demonstrating their cell type-selectivity. The supramolecular complexes represent attractive molecular tools to decipher the role of PMNs in infection and inflammation or for the development of novel therapeutic approaches for diseases that are associated with hyperactivity and reactivity of PMNs such as post-traumatic injury.

Nanoformulation properties, characterization, and behavior in complex biological matrices: Challenges and opportunities for brain-targeted drug delivery applications and enhanced translational potential

Nanocarriers (synthetic/cell-based have attracted enormous interest for various therapeutic indications, including neurodegenerative disorders. A broader understanding of the impact of nanomedicines design is now required to enhance their translational potential. Nanoformulations in vivo journey is significantly affected by their physicochemical properties including the size, shape, hydrophobicity, elasticity, and surface charge/chemistry/morphology, which play a role as an interface with the biological environment. Understanding protein corona formation is crucial in characterizing nanocarriers and evaluating their interactions with biological systems. In this review, the types and properties of the brain-targeted nanocarriers are discussed. The biological factors and nanocarriers properties affecting their in vivo behavior are elaborated. The compositional description of cell culture and biological matrices, including proteins potentially relevant to protein corona built-up on nanoformulation especially for brain administration, is provided. Analytical techniques of characterizing nanocarriers in complex matrices, their advantages, limitations, and implementation challenges in industrial GMP environment are discussed. The uses of orthogonal complementary characterization approaches of nanocarriers are also covered.

110th Anniversary: Nanoparticle mediated drug delivery for the treatment of Alzheimer's disease: Crossing the blood-brain barrier

Alzheimer's disease is an irreversible neurodegenerative disorder affecting approximately 6 million Americans, 90% of which are over the age of 65. The hallmarks of the disease are represented by amyloid plaques and neurofibrillary tangles. While the neuronal characteristics of Alzheimer's disease are well known, current treatments only provide temporary relief of the disease symptoms. Many of the approved therapeutic agents for the management of cognitive impairments associated with the disease are based on neurotransmitter or enzyme modulation. However, development of new treatment strategies is limited due to failures associated with poor drug solubility, low bioavailability, and the inability to overcome obstacles present along the drug delivery route. In addition, treatment technologies must overcome the challenges presented by the blood-brain barrier. This complex and highly regulated barrier surveys the biochemical, physicochemical, and structural features of nearby molecules at the periphery, only permitting passage of select molecules into the brain. To increase drug efficacy to the brain, many nanotechnology-based platforms have been developed. These methods for assisted drug delivery employ sophisticated design strategies and offer serveral advantages over traditional methods. For example, nanoparticles are generally low-cost technologies, which can be used for non-invasive administrations, and formulations are highly tunable to increase drug loading, targeting, and release efficacy. These nanoscale systems can facilitate passage of drugs through the blood-brain barrier, thus improving the bioavailability, pharmacokinetics, and pharmacodynamics of therapeutic agents. Examples of such nanocarriers which are discussed herein include polymeric nanoparticles, dendrimers, and lipid-based nanoparticles.