Self-assembled peptide-polyoxometalate hybrid nanospheres: two in one enhances targeted inhibition of amyloid β-peptide aggregation associated with Alzheimer's disease

Detection of Femtomolar Amyloid-β Peptides for Early-Stage Identification of Alzheimer's Amyloid-β Aggregation with Functionalized Gold Nanoparticles

Progressive amyloid-β (Aβ) fibrillar aggregates have long been considered as the pathogenesis of Alzheimer's disease (AD). Biocompatible and stable cysteine-Aβ peptide-conjugated gold nanoparticles (Cys-Aβ@AuNP) are demonstrated as suitable materials for detecting subfemtomolar Aβ peptides in human plasma. Incubation with Aβ peptides causes the Cys-Aβ@AuNP to aggregate and changes its absorption spectra. The spectral change is especially apparent and noticeable when detecting subfemtomolar Aβ peptides, and the aggregates contain only two or three AuNPs. Cys-Aβ@AuNP can also be used to identify early-stage Aβ oligomerization, which is not possible using the conventional method, in which the fluorescence of thioflavin-T is measured. The ability to detect Aβ oligomerization can facilitate therapeutics for AD. In addition, the binding of Aβ peptides by Cys-Aβ@AuNP in combination with centrifugation redirects the conventional Aβ aggregation pathway and can effectively inhibit the formation of toxic Aβ oligomers or fibrils. Therefore, the proposed Cys-Aβ@AuNP can also be used to develop effective therapeutic agents to inhibit Aβ aggregation. The results obtained in this study are expected to open revolutionary ways to both detect and inhibit Aβ aggregation at an early stage.

Novel fabrication of Cu(II)-incorporated chiral d-penicillamine-chitosan nanocomposites enantio-selectively inhibit the induced amyloid β aggregation for Alzheimer's disease therapy

It is well known that the chiral materials combined with metal ion's structure have been identified as promising candidate for the nursing Alzheimer Disease (AD) treatment, particularly to inhibit amyloid (Aβ) due to their significant pharmacological effect on the living bodies. In the present study, Cu(II)/Chitosan nanocomposite caped with chiral penicillamine (Cu@D-PEN/Chitosan) have been synthesized and used as an effective amyloid-β (Aβ) inhibitor. The composite formations of the samples were confirmed from the FTIR and XRD, studies. FE-SEM, TEM and AFM studies have been carried out to depict the morphological analysis of the nanocomposites. The prepared samples have also been subjected to various in vitro studies such as encapsulation efficiency, drug loading capacity, drug release and biodegrading or compatibility of the nanocomposites to support the Aβ aggregation inhibiting ability investigations. It was observed that the increase in the concentration of the Cu@D-PEN/Chitosan enhancing the Aβ inhibiting ability. Thus, the Cu(II)@D-PEN/Chitosan showed improving memory effect suggesting that Cu(II)@D-PEN/Chitosan nanocomposites may be a potential candidate for inhibiting the Aβ aggregation in nursing AD treatment.

Targeting Amyloids with Coated Nanoparticles: A Review on Potential Combinations of Nanoparticles and Bio-Compatible Coatings

Amyloidosis is the major cause of many neurodegenerative diseases, such as, Alzheimer's and Parkinson's where the misfolding and deposition of a previously functional protein make it inept for carrying out its function. The genesis of amyloid fibril formation and the strategies to inhibit it have been studied extensively, although some parts of this puzzle still remain unfathomable to date. Many classes of molecules have been explored as potential drugs in vitro, but their inability to work in vivo by crossing the blood-brain-barrier has made them an inadequate treatment option. In this regard, nanoparticles (NPs) have turned out to be an exciting alternative because they could overcome many drawbacks of previously studied molecules and provide advantages, such as, greater bioavailability of molecules and target-specific delivery of drugs. In this paper, we present an overview on several coated NPs which have shown promising efficiency in inhibiting fibril formation. A hundred and thirty papers published in the past two decades have been comprehensively reviewed, which majorly encompass NPs comprising different materials like gold, silver, iron-oxide, poly(lactic-co-glycolic acid), polymeric NP, etc., which are coated with various molecules of predominantly natural origin, such as different types of amino acids, peptides, curcumin, drugs, catechin, etc. We hope that this review will shed light on the advancement of symbiotic amalgamation of NPs with molecules from natural sources and will inspire further research on the tremendous therapeutic potential of these combinations for many amyloid-related diseases.

Advancements in the Application of Nanomedicine in Alzheimer's Disease: A Therapeutic Perspective

Alzheimer's disease (AD) is a progressive neurodegenerative disease that affects most people worldwide. AD is a complex central nervous system disorder. Several drugs have been designed to cure AD, but with low success rates. Because the blood-brain and blood-cerebrospinal fluid barriers are two barriers that protect the central nervous system, their presence has severely restricted the efficacy of many treatments that have been studied for AD diagnosis and/or therapy. The use of nanoparticles for the diagnosis and treatment of AD is the focus of an established and rapidly developing field of nanomedicine. Recent developments in nanomedicine have made it possible to effectively transport drugs to the brain. However, numerous obstacles remain to the successful use of nanomedicines in clinical settings for AD treatment. Furthermore, given the rapid advancement in nanomedicine therapeutics, better outcomes for patients with AD can be anticipated. This article provides an overview of recent developments in nanomedicine using different types of nanoparticles for the management and treatment of AD.

A Flower-like Brain Targeted Selenium Nanocluster Lowers the Chlorogenic Acid Dose for Ameliorating Cognitive Impairment in APP/PS1 Mice

Aβ aggregation-related neuroinflammation and imbalance of brain glucose homeostasis play important roles in the pathological process of Alzheimer's disease (AD). Chlorogenic acid (CGA) is one of the most common dietary polyphenols with neuroprotective effects. However, due to the low bioavailability of CGA, its application dose is usually high in vivo. In our previous study, the spherical selenium nanoparticles act as drug carriers to improve the bioactivity of resveratrol. Here, the brain-targeting peptide (TGN peptide) and CGA were used to prepare a new flowerlike selenium nanocluster (TGN-CGA@SeNCs) for enhancing the bioavailability of CGA. After decoration on selenium nanoclusters, the solubility and stability of CGA was obviously increased. Oral administration of a low dose of CGA (80 mg/kg/body weight) only slightly inhibited Aβ aggregate-related neuroinflammation and glucose homeostasis disorder in the brain. Moreover, CGA showed less effect on increasing the diversity and richness of gut microbiota. At the same concentration, the CGA-modified selenium nanocluster (CGA@SeNCs) and TGN-CGA@SeNCs showed better function in ameliorating the gut microbiota disorder. Especially, TGN-CGA@SeNCs significantly increased the relative abundance of Turicibacter, Colidextribacter, Ruminococcus, Alloprevotella, and Alistipes against oxidative stress, inflammation, and glucose homeostasis imbalance. Notably, only TGN-CGA@SeNCs can transport through the blood-brain barrier (BBB), and TGN-CGA@SeNCs showed better effects than CGA@SeNCs in regulating Aβ aggregation and improving brain glucose homeostasis. These results broadened the application of TGN-CGA@SeNCs, effectively improving the bioactivity of CGA, which also lowers the CGA dose for preventing AD progression.

Impact of nanoparticles on amyloid β-induced Alzheimer's disease, tuberculosis, leprosy and cancer: a systematic review

Nanotechnology is an interdisciplinary domain of science, technology and engineering that deals with nano-sized materials/particles. Usually, the size of nanoparticles lies between 1 and 100 nm. Due to their small size and large surface area-to-volume ratio, nanoparticles exhibit high reactivity, greater stability and adsorption capacity. These important physicochemical properties attract scientific community to utilize them in biomedical field. Various types of nanoparticles (inorganic and organic) have broad applications in medical field ranging from imaging to gene therapy. These are also effective drug carriers. In recent times, nanoparticles are utilized to circumvent different treatment limitations. For example, the ability of nanoparticles to cross the blood-brain barrier and having a certain degree of specificity towards amyloid deposits makes themselves important candidates for the treatment of Alzheimer's disease. Furthermore, nanotechnology has been used extensively to overcome several pertinent issues like drug-resistance phenomenon, side effects of conventional drugs and targeted drug delivery issue in leprosy, tuberculosis and cancer. Thus, in this review, the application of different nanoparticles for the treatment of these four important diseases (Alzheimer's disease, tuberculosis, leprosy and cancer) as well as for the effective delivery of drugs used in these diseases has been presented systematically. Although nanoformulations have many advantages over traditional therapeutics for treating these diseases, nanotoxicity is a major concern that has been discussed subsequently. Lastly, we have presented the promising future prospective of nanoparticles as alternative therapeutics. In that section, we have discussed about the futuristic approach(es) that could provide promising candidate(s) for the treatment of these four diseases.

Polyoxometalate-peptide hybrid materials: from structure-property relationships to applications

Organo-functionalisation of polyoxometalates (POMs) represents an effective approach to obtain diverse arrays of functional structures and materials, where the introduction of organic moieties into the POM molecules can dramatically change their surface chemistry, charge, polarity, and redox properties. The synergistic combination of POMs and peptides, which perform a myriad of essential roles within cellular biochemistry, including protection and transport in living organisms, leads to functional hybrid materials with unique properties. In this Perspective article, we present the principal synthetic routes to prepare and characterise POM-peptide hybrids, together with a comprehensive description of how their properties - such as redox chemistry, stereochemistry and supramolecular self-assembly - give rise to materials with relevant catalytic, adhesive, and biomedical applications. By presenting the state-of-the-art of the POM-peptide field, we show specifically how emerging chemical approaches can be harnessed to develop tailored POM-peptide materials with synergistic properties for applications in a variety of disciplines.

Advanced nanomaterials for modulating Alzheimer's related amyloid aggregation

Alzheimer's disease (AD) is a common neurodegenerative disease that brings about enormous economic pressure to families and society. Inhibiting abnormal aggregation of Aβ and accelerating the dissociation of aggregates is treated as an effective method to prevent and treat AD. Recently, nanomaterials have been applied in AD treatment due to their excellent physicochemical properties and drug activity. As a drug delivery platform or inhibitor, various excellent nanomaterials have exhibited potential in inhibiting Aβ fibrillation, disaggregating, and clearing mature amyloid plaques by enhancing the performance of drugs. This review comprehensively summarizes the advantages and disadvantages of nanomaterials in modulating amyloid aggregation and AD treatment. The design of various functional nanomaterials is discussed, and the strategies for improved properties toward AD treatment are analyzed. Finally, the challenges faced by nanomaterials with different dimensions in AD-related amyloid aggregate modulation are expounded, and the prospects of nanomaterials are proposed.

Promising application of polyoxometalates in the treatment of cancer, infectious diseases and Alzheimer's disease

As shown in studies conducted in recent decades, polyoxometalates (POMs), as inorganic metal oxides, have promising biological activities, including antitumor, anti-infectious and anti-Alzheimer’s activities, due to their special structures and properties. However, some side effects impede their clinical applications to a certain extent. Compared with unmodified POMs, POM-based inorganic–organic hybrids and POM-based nanocomposite structures show significantly enhanced bioactivity and reduced side effects. In this review, we introduce the biological activities of POMs and their derivatives and highlight the side effects of POMs on normal cells and organisms and their possible mechanisms of action. We then propose a development direction for overcoming their side effects. POMs are expected to constitute a new generation of inorganic metal drugs for the treatment of cancer, infectious diseases, and Alzheimer's disease.

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Lanthanides Singing the Blues: Their Fascinating Role in the Assembly of Gigantic Molybdenum Blue Wheels

Molybdenum blues (MBs) are a distinct class of polyoxometalates, exhibiting versatile/impressive architectures and high structural flexibility. In acidified and reduced aqueous environments, isopolymolybdates generate precisely organizable building blocks, which enable unique nanoscopic molecular systems (MBs) to be constructed and further fine-tuned by hetero elements such as lanthanide (Ln) ions. This Review discusses wheel-shaped MB-based structure types with strong emphasis on the ∼30 Ln-containing MBs as of August 2021, which include both organically hybridized and nonhybridized structures synthesized to date. The spotlight is thereby put on the lanthanide ions and ligand types, which are crucial for the resulting Ln-patterns and alterations in the gigantic structures. Several critical steps and reaction conditions in their synthesis are highlighted, as well as appropriate methods to investigate them both in solid state and in solution. The final section addresses the homogeneous/heterogeneous catalytic, molecular recognition and separation properties of wheel-shaped Ln-MBs, emphasizing their inimitable behavior and encouraging their application in these areas.

Phosphorylation of covalent organic framework nanospheres for inhibition of amyloid-β peptide fibrillation

The development and exploration of new nanostructural inhibitors against Alzheimer's disease (AD)-associated amyloid-β (Aβ) fibrillation have attracted extensive attention and become a new frontier in nanomedicine. However, focusing on finding an effective nanostructure is one of the most challenging parts of the therapeutics task. Herein, nanoscale spherical covalent organic frameworks (COFs) via post-synthetic functionalization with sodium phosphate (SP) groups on the channel networks were found to efficiently inhibit Aβ fibrillation. The as-prepared uniform SP-COF nanospheres with high surface area, good crystallinity, and chemical stability were characterized by multifarious microscopic and spectroscopic techniques. Moreover, molecular dynamics simulation together with fibrillation kinetics and cytotoxicity assay experiments shows that there were restricted-access adsorption channels in the SP-COFs which were formed by the cavities with size and functional groups accommodated to the Aβ peptide sequence and significantly affected the fibrillation and cytotoxicity of Aβ. Transmission electron microscopy (TEM), dynamic light scattering (DLS) monitoring, isothermal titration calorimetry (ITC), Fourier transform infrared (FT-IR) and circular dichroism (CD) spectra measurements, and confocal imaging observation were performed to understand the inhibition mechanism and influencing factors of the SP-COFs. To our knowledge, our strategy is the first exploration of COF-based anti-amyloidogenic nanomaterials with high affinity and specific targeting, which are crucial for the inhibition of Aβ fibrillation for AD prevention and treatment.

Nanoscale spherical COFs via phosphorylation functionalization were found to efficiently inhibit fibrillation of the Alzheimer's disease-associated Aβ peptide.

Current State-of-the-Art and New Trends in Self-Assembled Nanocarriers as Drug Delivery Systems

Self-assembled nanocarrier drug delivery has received profuse attention in the field of diagnosis and treatment of diseases. These carriers have proved that serious life-threatening diseases can be eliminated evidently by virtue of their characteristic design and features. This review is aimed at systematically presenting the research and advances in the field of self-assembled nanocarriers such as polymeric nanoparticles, dendrimers, liposomes, inorganic nanocarriers, solid lipid nanoparticles, polymerosomes, micellar systems, niosomes, and some other nanoparticles. The self-assembled delivery of nanocarriers has been developed in recent years for targeting diseases. Some of the innovative attempts with regard to prolonging drug action, improving bioavailability, avoiding drug resistance, enhancing cellular uptake, and so on have been discussed. The discussion about various delivery systems included the investigation conducted at the preliminary stage, i.e., preclinical trials and assessment of safety. The clinical studies of some of the recently developed self-assembled products are currently at the clinical trial phase or FDA approved.

Recent Advances in the Application Peptide and Peptoid in Diagnosis Biomarkers of Alzheimer's Disease in Blood

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases with irreversible damage of the brain and a continuous pathophysiological process. Early detection and accurate diagnosis are essential for the early intervention of AD. Precise detection of blood biomarkers related to AD could provide a shortcut to identifying early-stage patients before symptoms. In recent years, targeting peptides or peptoids have been chosen as recognition elements in nano-sensors or fluorescence detection to increase the targeting specificity, while peptide-based probes were also developed considering their specific advantages. Peptide-based sensors and probes have been developed according to different strategies, such as natural receptors, high-throughput screening, or artificial design for AD detection. This review will briefly summarize the recent developments and trends of AD diagnosis platforms based on peptide and peptoid as recognition elements and provide insights into the application of peptide and peptoid with different sources and characteristics in the diagnosis of AD biomarkers.

Breaker peptides against amyloid-β aggregation: a potential therapeutic strategy for Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder, for which blocking the early steps of extracellular misfolded amyloid-β (Aβ) aggregation is a promising therapeutic approach. However, the pathological features of AD progression include the accumulation of intracellular tau protein, membrane-catalyzed cell death and the abnormal deposition of Aβ. Here, we focus on anti-amyloid breaker peptides derived from the Aβ sequence and non-Aβ-based peptides containing both natural and modified amino acids. Critical aspects of the breaker peptides include N-methylation, conformational restriction through cyclization, incorporation of unnatural amino acid, fluorinated molecules, polymeric nanoparticles and PEGylation. This review confers a general idea of such breaker peptides with in vitro and in vivo studies, which may advance our understanding of AD pathology and develop an effective treatment strategy against AD.

Nanomaterials for Modulating the Aggregation of β-Amyloid Peptides

The aberrant aggregation of amyloid-β (Aβ) peptides in the brain has been recognized as the major hallmark of Alzheimer's disease (AD). Thus, the inhibition and dissociation of Aβ aggregation are believed to be effective therapeutic strategiesforthe prevention and treatment of AD. When integrated with traditional agents and biomolecules, nanomaterials can overcome their intrinsic shortcomings and boost their efficiency via synergistic effects. This article provides an overview of recent efforts to utilize nanomaterials with superior properties to propose effective platforms for AD treatment. The underlying mechanismsthat are involved in modulating Aβ aggregation are discussed. The summary of nanomaterials-based modulation of Aβ aggregation may help researchers to understand the critical roles in therapeutic agents and provide new insight into the exploration of more promising anti-amyloid agents and tactics in AD theranostics.

Tau-Targeted Multifunctional Nanoinhibitor for Alzheimer's Disease

With the failure of various amyloid-β-targeted drugs for Alzheimer's disease (AD) in clinical trials, tau protein has gained growing attention as an alternative therapeutic target in recent years. The aggregation of tau exerts neurotoxicity, and its spreading in the brain is associated with increasing severity of clinical symptoms for AD patients; thus tau-targeting therapies hold great potential against AD. Here, a tau-targeted multifunctional nanoinhibitor based on self-assembled polymeric micelles decorated with tau-binding peptide is devised for AD treatment. Through the multivalent binding effect with the aggregating protein, this nanoinhibitor is capable of efficiently inhibiting tau protein aggregation, recognizing tau aggregates, and blocking their seeding in neural cells, thus remarkably mitigating tau-mediated cytotoxicity. Moreover, the formed nanoinhibitor-tau complex after binding is more easily degraded than mature tau aggregates, which will be conducive to enhance the therapeutic effect. We believe that this multifunctional nanoinhibitor will promote the development of new antitau strategies for AD treatment.

Current Strategies for Modulating Aβ Aggregation with Multifunctional Agents

Alzheimer's disease (AD), as the primary cause of dementia, has seriously affected millions of people worldwide and brought a very heavy financial and social burden. With the growth of population and aging, the situation will worsen unless efficacious drugs are found to reverse, stop, or even slow down disease progression. More and more evidence has demonstrated that amyloid-β (Aβ) aggregation is an upstream causative factor in AD pathogenesis and then triggers a slew of pathological events. Furthermore, the concentrated redox metal ions in the AD brain, especially Cu(II), can significantly exacerbate Aβ aggregation and contribute to the formation of neurotoxic reactive oxygen species (ROS). Therefore, the inhibition of Aβ aggregation and relief of amyloidosis-initiated neurotoxicity play a critical role in AD treatment. Until now, several methods have been proposed to modulate Aβ aggregation, such as developing aggregation inhibitors to interfere with Aβ assembly via noncovalent interactions, copper chelators to cut off metal-accelerated Aβ aggregation and concomitant cytotoxicity, photooxidation to reduce the hydrophobicity and aggregation tendency of Aβ, thermal dissociation to disrupt amyloid aggregates susceptible to temperature, degradation with artificial protease to fracture the Aβ peptide into small fragments, and the clearance of peripheral Aβ to bypass the obstruction of the BBB and reduce the Aβ burden.In this Account, we focus on our contributions to the development of Aβ-targeted multifunctional molecules and nanoparticles, emphasizing the diversified strategies and synergistic therapeutic effects. These therapeutic agents possess the following multifunctionalities: (1) compared with frequently used aggregation inhibitors restricted by intrinsically feeble and sensitive noncovalent interactions, multifunctional agents can efficiently block Aβ aggregation by exploiting two or more Aβ-specific inhibition strategies simultaneously; (2) apart from regulating Aβ aggregation, multipronged agents can also target and modulate other pathological factors in AD pathogenesis, such as increased oxidative stress, abnormal copper accumulation, and irreversible neuron loss; (3) multifunctional platforms with both diagnostic and therapeutic modalities through integrating in situ imaging, real-time diagnostics, a multitarget direction, stimuli-responsive drug release, and the blood-brain barrier (BBB) translocation features are instrumental in improving drug levels at trouble sites, diminishing off-target adverse reactions, evaluating therapeutic effects, and averting overtreatment.Given the fact that amyloid aggregation, local inflammation, and metal dyshomeostasis are universal biomarkers shared by various neurodegenerative disorders, this Account provides a perspective for the evolution of customized therapeutic agents with multiple reactivities for other neurodegenerative diseases. In addition, recent studies have indicated that Aβ aggregates can enter the nucleus and induce DNA damage and anomalous conformational transition. We also explore the influences of DNA on the biological effects of Aβ aggregates.

Recent Progress in Ionic Coassembly of Cationic Peptides and Anionic Species

Peptide assembly has been extensively exploited as a promising platform for the creation of hierarchical nanostructures and tailor-made bioactive materials. Ionic coassembly of cationic peptides and anionic species is paving the way to provide particularly important contribution to this topic. In this review, the recent progress of ionic coassembly soft materials derived from the electrostatic coupling between cationic peptides and anionic species in aqueous solution is systematically summarized. The presentation of this review starts from a brief background on the general importance and advantages of peptide-based ionic coassembly. After that, diverse combinations of cationic peptides with small anions, macro- and/or oligo-anions, anionic polymers, and inorganic polyoxometalates are described. Emphasis is placed on the hierarchical structures, value-added properties, and applications. The molecular design of cationic peptides and the general principles behind the ionic coassembled structures are discussed. It is summarized that the combination of interesting and unique characteristics that arise both from the chemical diversity of peptides and the wide range of anionic species may contribute in a variety of output, including drug delivery, tissue engineering, gene transfection, and antibacterial activity. The emergent new phenomena and findings are illustrated. Finally, the outlook for the peptide-based ionic coassembly systems is also presented.

Nanolipid-loaded Preyssler polyoxometalate: Synthesis, characterization and invitro inhibitory effects on HepG2 tumor cells

Polyoxometalate-based drugs have been selected by some researchers as alternative antitumor substances with promising results in suppression of tumor growth because of low toxicity towards the human body and high activity. In this research, for the first time, nanolipid-loaded Preyssler polyoxometalate with diameters of 230-250 nm was synthesized and characterized by the Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDAX), Atomic Force Microscopy (AFM), and Infrared (IR) spectroscopy. The nanoliposomes were found to be nearly spherical, without any agglomeration with the Entrapment Efficiency of 53.8%. In -vitro antitumor activity of the synthesized nanoliposomes was investigated using the MTT method on HepG2 tumor cells. Our findings showed enhanced anticancer activity for the nanolipid-loaded Preyssler (NLP) compared to the Sorafenib as a commercially drug at 72 h. Selectivity of the synthesized NLP and Sorafenib for cancer cells versus primary HFF cells was obtained as 4.2 and 2.2, respectively. The IC50 value of the loaded nanoliposomes for cancer cells and normal cells was equal to 470 and 2000 μg/mL, respectively at 72 h, which was much better compared to that of the Sorafenib (7 and 16 μg/mL, respectively).

Effective inhibitory activity against MCF-7, A549 and HepG2 cancer cells by a phosphomolybdate based hybrid solid

A novel P₂Mo₅ cluster based hybrid solid [{4,4′-H₂bpy}{4,4′-Hbpy}₂{H₂P₂Mo₅O₂₃}]·5H₂O with effective anti-proliferation activity against MCF-7, HepG2 and A549 cancer cells comparable with a routinely used chemotherapeutic agent, methotrexate (MTX).

Sarsasapogenin: A steroidal saponin from Asparagus racemosus as multi target directed ligand in Alzheimer's disease

Alzheimer's disease (AD) is multi-factorial disorder characterized by impaired memory and cognition deficit. AD is characterized by impaired cholinergic transmission, extracellular amyloid beta deposits, neurofibrillary tangles and oxidative stress. A multi-target directed ligand (MTDL) approach is required to devise a therapeutic strategy against AD. In the present study, Asparagus racemosus aqueous extract was chosen, as it possess abundant medicinal properties including nootropic effect mentioned in ancient Ayurvedic texts. Moreover, its secondary metabolite sarsasapogenin (SRS) was also selected for this multi-target study for the very first time. The current study demonstrated that sarsasapogenin significantly inhibits key enzymes involved in pathogenesis of AD which are acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), BACE1 and MAO-B in a concentration dependent manner. SRS also exhibited anti-amyloidogenic, anti-oxidant and neuroprotective effects by in vitro studies. The IC₅₀ values of SRS is 9.9 μM and 5.4 μM for AChE and BuChE respectively. SRS also significantly inhibited Aβ42 fibrillization up to 68% at 40 μM concentration as compared to control. TEM visualization showed Aβ aggregates as short and scattered fibril clearly indicating SRS significantly inhibited peptide nucleation and fibril formation. Furthermore, the SRS was found to exert neuroprotective effect on PC12 cells against Aβ42 and H₂O₂-mediated cytotoxicity. The cell survival was 62% and 69% against Aβ42 and H₂O₂-mediated cytotoxicity, respectively. SRS also inhibited monoaminoxidase-B (MAO-B) and BACE1 enzymes in concentration dependent manner. Molecular docking studies indicated that SRS binds to the catalytic sites of multiple targets (AChE, BuChE, Aβ42, BACE1, and MAO-B) in a significant manner that might having disease-modifying effects. Thus SRS is acting as suitable lead and can be utilised as MTDL compound for factors implicated in AD.

Polyoxometalate-antioxidant peptide assembly materials with NIR-triggered photothermal behaviour and enhanced antibacterial activity

Herein, a novel photothermal agent based on polyoxometalate clusters and food-borne antioxidant peptides was exploited to overcome the inherent problems of poor photothermal stability of polyoxometalate photothermal materials, which commonly appear in the current stage of development, and the inevitable simultaneous inflammatory responses during the therapeutic process.

Obstacles to translating the promise of nanoparticles into viable amyloid disease therapeutics

Nanoparticles (NPs) constitute a powerful therapeutic platform with exciting prospects as potential inhibitors of amyloid-[Formula: see text] (Aβ) aggregation, a process associated with Alzheimer's disease (AD). Researchers have synthesized and tested a large collection of NPs with disparate sizes, shapes, electrostatic properties and surface ligands that evoke a variety of responses on Aβ aggregation. In spite of a decade of research on the NP-Aβ system and many promising experimental results, NPs have failed to progress to any level of clinical trials for AD. A theoretical framework with which to approach this physical system is presented featuring two simple metrics, (1) the extent to which NPs adsorb Aβ, and (2) the degree to which interaction with a NP alters Aβ conformation relative to aggregation propensity. Most of our current understanding of these two interactions has been gained through experimentation, and many of these studies are reviewed herein. We also provide a potential roadmap for studies that we believe could produce viable NPs as an effective AD therapeutic platform.

Interactions between polyoxometalates and biological systems: from drug design to artificial enzymes

Polyoxometalates have long been studied in a variety of biological applications. Interactions between the highly charged POM molecules and biological molecules frequently occur through hydrogen-bonding and electrostatic interactions. Tellurium-centred Anderson-Evans POMs show exceptional promise as crystallization agents, while acidic and metal-substituted POMs may provide interesting alternatives to enzymes in proteomics applications. While POMs also show interesting results in a number of medicinal applications, for example as anti-amyloid agents for the treatment of Alzheimer's disease and as anti-tumoral agents, their use is often impeded by their toxicity. Many recent studies have therefore focussed on POM-functionalization to reduce toxicity and increase activity by addition of biological targeting molecules.

Self-Assembly Molecular Chaperone to Concurrently Inhibit the Production and Aggregation of Amyloid β Peptide Associated with Alzheimer's Disease

Amyloid β peptide (Aβ) plays a crucial role in the pathogenesis of Alzheimer's disease (AD). Currently, decreasing Aβ production and preventing Aβ aggregation are thought to be important strategies in anti-AD therapy. However, inhibiting Aβ production or aggregation in isolation is not sufficient to reverse the neurodegenerative process of AD patients in clinical testing. Here, a self-assembly molecular chaperone (SAMC) consisting of γ-secretase inhibitor DAPT and mixed-shell polymeric micelles is devised, serving as a bifunctional suppressor of AD. This two-in-one combinational system can simultaneously inhibit Aβ production and aggregation, which would contribute to enhancing the therapeutic effect by decreasing Aβ levels. Decorating a neuron-specific RVG29 peptide onto the surface, the DAPT-incorporated SAMC can specifically target neuronal cells and, thus, will relieve the strong side effect of DAPT on normal cells. Therefore, this combination strategy holds great potential to open up an avenue for AD treatment.

Application of nanodiagnostics and nanotherapy to CNS diseases

Alzheimer's disease, Parkinson's disease and stroke are the most common CNS diseases, all characterized by progressive cellular dysfunction and death in specific areas of the nervous system. Therapeutic development for these diseases has lagged behind other disease areas due to difficulties in early diagnosis, long disease courses and drug delivery challenges, not least due to the blood-brain barrier. Over recent decades, nanotechnology has been explored as a potential tool for the diagnosis, treatment and monitoring of CNS diseases. In this review, we describe the application of nanotechnology to common CNS diseases, highlighting disease pathogenesis and the underlying mechanisms and promising functional outcomes that make nanomaterials ideal candidates for early diagnosis and therapy. Moreover, we discuss the limitations of nanotechnology, and possible solutions.

Near-Infrared Switchable Fullerene-Based Synergy Therapy for Alzheimer's Disease

C60 has a special dual function; it can act as both a powerful reactive oxygen species (ROS) producer under UV or visible light and an ROS scavenger in the dark. However, ROS has double-edged effects in living systems. It is still a great challenge for biomedical application to switch and adjust the two opposite properties of C60 in one system. Herein, UCNP@C60 -pep (UCNP: upconversion nanoparticle, pep: Aβ-target peptide KLVFF) is designed as a near-infrared-switchable nanoplatform for synergy therapy of Alzheimer's disease (AD). Under near-infrared (NIR) light, the Aβ-targeting hybrid nanoparticles produce ROS and result in Aβ photooxygenation, which can hinder Aβ aggregation and mitigate the attendant cytotoxicity. In the dark, UCNP@C60 -pep shows protective effects against the increased oxidative stress. The ROS-generating and ROS-quenching abilities of UCNP@C60 -pep are both beneficial for decreasing Aβ-induced neurotoxicity and extending the longevity of the commonly used transgenic AD model Caenorhabditis elegans CL2006. Moreover, UCNP@C60-pep can also be used for upconversion luminescence (UCL) and magnetic resonance imaging (MRI), which has benefits for "image-guided therapy." This study may offer a new perspective for the biological applications of C60 .

Selective Targeting of Proteins by Hybrid Polyoxometalates: Interaction Between a Bis-Biotinylated Hybrid Conjugate and Avidin

The Keggin-type polyoxometalate [γ-SiW₁₀O₃₆]^8- was covalently modified to obtain a bis-biotinylated conjugate able to bind avidin. Spectroscopic studies such as UV-vis, fluorimetry, circular dichroism, coupled to surface plasmon resonance technique were used to highlight the unique interplay of supramolecular interactions between the homotetrameric protein and the bis-functionalized polyanion. In particular, the dual recognition mechanism of the avidin encompasses (i) a complementary electrostatic association between the anionic surface of the polyoxotungstate and each positively charged avidin subunit and (ii) specific host-guest interactions between each biotinylated arm and a corresponding pocket on the tetramer subunits. The assembly exhibits peroxidase-like reactivity and it was used in aqueous solution for L-methionine methyl ester oxidation by H₂O₂. The recognition phenomenon was then exploited for the preparation of layer-by-layer films, whose structural evolution was monitored in situ by ATR-FTIR spectroscopy. Finally, cell tracking studies were performed by exploiting the specific interactions with a labeled streptavidin.

Self-Assembly of Polyoxometalate-Peptide Hybrids in Solution: Elucidating the Contributions of Multiple Possible Driving Forces

Incorporating the building blocks of nature (e.g., peptides and DNA) into inorganic polyoxometalate (POM) clusters is a promising approach to improve the compatibilities of POMs in biological fields. To extend their biological applications, it is necessary to understand the importance of different non‐covalent interactions during self‐organization. A series of Anderson POM–peptide hybrids have been used as a simple model to demonstrate the role of different interactions in POM–peptide (biomolecules) systems. Regardless of peptide chain length, these hybrids follow similar solution behaviors, forming hollow, spherical supramolecular structures in acetonitrile/water mixed solvents. The incorporation of peptide tails introduces interesting stimuli‐responsive properties to temperature, hybrid concentration, solvent polarity and ionic strength. Unlike the typical bilayer amphiphilic vesicles, they are found to follow the blackberry‐type assemblies of hydrophilic macroions, which are regulated by electrostatic interaction and hydrogen bonding. The formation of electrostatic assemblies before the supramolecular formation is confirmed by ion‐mobility mass spectrometry (IMS‐MS).

Self-Sorting of Heteroanions in the Assembly of Cross-Shaped Polyoxometalate Clusters

Heteroanion (HA) moieties have a key role in templating of heteropolyoxometalate (HPA) architectures, but clusters templated by two different templates are rarely reported. Herein, we show how a cross-shaped HPA-based architecture can self-sort the HA templates by pairing two different guests into a divacant {XYW15O54} building block, with four of these building block units being linked together to complete the cross-shaped architecture. We exploited this observation to incorporate HA templates into well-defined positions within the clusters, leading to the isolation of a collection of mixed-HA templated cross-shaped polyanions [(XYW15O54)4(WO2)4]32-/36- (X = H-P, Y = Se, Te, As). The template positions have been unambiguously determined by single crystal X-ray diffraction, NMR spectroscopy, and high-resolution electrospray ionization mass spectrometry; these studies demonstrated that the mixed template containing HPA clusters are the preferred products which crystallize from the solution. Theoretical studies using DFT calculations suggest that the selective self-sorting originates from the coordination of the template in solution. The cross-shaped polyoxometalate clusters are redox-active, and the ability of molecules to accept electrons is slightly modulated by the HA incorporated as shown by differential pulse voltammetry experiments. These results indicate that the cross-shaped HPAs can be used to select templates from solution, and themselves have interesting geometries, which will be useful in developing functional molecular architectures based upon HPAs with well-defined structures and electronic properties.

Stereochemistry and amyloid inhibition: Asymmetric triplex metallohelices enantioselectively bind to Aβ peptide

Stereochemistry is vital for pharmaceutical development and can determine drug efficacy. Herein, 10 pairs of asymmetric triplex metallohelix enantiomers as a library were used to screen inhibitors of amyloid β (Aβ) aggregation via a fluorescent cell-based high-throughput method. Intriguingly, Λ enantiomers show a stronger inhibition effect than Δ enantiomers. In addition, the metallohelices with aromatic substituents are more effective than those without, revealing that these groups play a key role in the Aβ interaction. Fluorescence stopped-flow kinetic studies indicate that binding of the Λ enantiomer to Aβ is much faster than that of the Δ enantiomer. Furthermore, studies in enzyme digestion, isothermal titration calorimetry, nuclear magnetic resonance, and computational docking demonstrate that the enantiomers bind to the central hydrophobic α-helical region of Aβ13-23, although with different modes for the Λ and Δ enantiomers. Finally, an in vivo study showed that these metallohelices extend the life span of the Caenorhabditis elegans CL2006 strain by attenuating Aβ-induced toxicity. Our work will shed light on the design and screening of a metal complex as an amyloid inhibitor against Alzheimer's disease.

Self-assembly study of nanometric spheres from polyoxometalate-phenylalanine hybrids, an experimental and theoretical approach

Polyoxometalate-amino acid hybrids (POM-FandPOM-FF) self-assemble into spherical architectures with high reproducibility in several “good–bad” solvent mixtures.

Chiral supramolecular coordination cages as high-performance inhibitors against amyloid-β aggregation

A family of chiral tetrahedral Ni₄⁸⁺ coordination cages with tunable size and multiple interaction sites can effectively inhibit Aβ aggregation.

Selective Isolation of Myosin Subfragment-1 with a DNA-Polyoxovanadate Bioconjugate

The bioconjugation of a polyoxometalate (POMs), i.e., dodecavanadate (V₁₂O₃₂), to DNA strands produces a functional labeled DNA primer, V₁₂O₃₂-DNA. The grafting of DNA primer onto streptavidin-coated magnetic nanoparticles (SVM) produces a novel composite, V₁₂O₃₂-DNA@SVM. The high binding-affinity of V₁₂O₃₂ with the ATP binding site in myosin subfragment-1 (S1) facilitates favorable adsorption of myosin, with an efficiency of 99.4% when processing 0.1 mL myosin solution (100 μg mL^-1) using 0.1 mg composite. Myosin adsorption fits the Langmuir model, corresponding to a theoretical adsorption capacity of 613.5 mg g^-1. The retained myosin is readily recovered by 1% SDS (m/m), giving rise to a recovery of 58.7%. No conformational change is observed for myosin after eliminating SDS by ultrafiltration. For practical use, high-purity myosin S1 is obtained by separation of myosin from the rough protein extract from porcine left ventricle, followed by digestion with α-chymotryptic and further isolation of S1 subfragment. The purified myosin S1 is identified with matrix-assisted laser desorption/ionization time-of-flight/mass spectrometry, giving rise to a sequence coverage of 38%.

Remodeling Tau and Prion Proteins Using Nanochaperons

There is increasing evidence that tau protein behaves in a prion-like manner in tauopathy. The stabilization of tau protein using a small molecular compound can limit tauopathy associated morbidity that advances with ageing. Here, a lab-on-a-chip experiment is reported, where gold citrate nanoparticles (5 nm, AuNPs) can remodel mutant tau protein (P301L) and prion, thus resolving the mutant tau- and prion-mediated impairment of kinesin cargo transport on microtubules. It is found that tau protein is overexpressed in Alzheimer's disease (AD) patient serum samples and the tau conformational change can also be affected in human serum samples of AD when treated with AuNPs ex vivo. Similarly, AuNPs reorganizing the prion protein and inducing conformational changes of prions in AD serum have been observed, while having no effect on alpha-synuclein in Parkinson patient serum. The mapping of AD serum mediated traffic jams, using particle tracking and mean square displacement analysis, and the observed recovery of uninterrupted processive motor functions by AuNP treatment show that kinesin cargo assays might be a useful method for future ex vivo validation of a targeted therapy against tauopathy before administration, a viable option to combat various neurodegenerative disorders arising from the susceptibility of amyloidogenic proteins toward aggregation.

The Anti-Proliferation Activity and Mechanism of Action of K12[V18O42(H₂O)]∙6H₂O on Breast Cancer Cell Lines

Polyoxometalates (POMs) are inorganic clusters that possess potential anti-bacterial, anti-viral, and anti-tumor activities. Herein, the in vitro anti-proliferation activities of K₁₂[V₁₈O₄₂(H₂O)]∙6H₂O (V₁₈) have been investigated on the MCF-7 and MDA-MB-231 cell lines. The results indicated that V₁₈ could inhibit the proliferation of MCF-7 (IC₅₀, 11.95 μM at 48 h) in a dose-dependent manner compared to the positive control, 5-fluorouracil (5-Fu, p < 0.05). The anti-proliferation activity of V₁₈ might be mediated by arrest of the MCF-7 cells in the G₂/M phase and induction of apoptosis and necrosis. Moreover, V₁₈ can effectively quench the fluorescence of ctDNA. The binding mode between them may be groove or outside stacking binding. V₁₈ can also effectively quench the intrinsic fluorescence of bovine serum albumin (BSA) and human serum albumin (HSA) via static quenching, and changed the conformation of BSA and HSA.

Using Multifunctional Peptide Conjugated Au Nanorods for Monitoring β-amyloid Aggregation and Chemo-Photothermal Treatment of Alzheimer's Disease

Development of sensitive detectors of Aβ aggregates and effective inhibitors of Aβ aggregation are of diagnostic importance and therapeutic implications for Alzheimer's disease (AD) treatment. Herein, a novel strategy has been presented by self-assembly of peptide conjugated Au nanorods (AuP) as multifunctional Aβ fibrillization detectors and inhibitors. Our design combines the unique high NIR absorption property of AuNRs with two known Aβ inhibitors, Aβ15-20 and polyoxometalates (POMs). The synthesized AuP can effectively inhibit Aβ aggregation and dissociate amyloid deposits with NIR irradiation both in buffer and in mice cerebrospinal fluid (CSF), and protect cells from Aβ-related toxicity upon NIR irradiation. In addition, with the shape and size-dependent optical properties, the nanorods can also act as effective diagnostic probes to sensitively detect the Aβ aggregates. This is the first report to integrate 3 segments, an Aβ-targeting element, a reporter and inhibitors, in one drug delivery system for AD treatment.

Chiral penicillamine-modified selenium nanoparticles enantioselectively inhibit metal-induced amyloid β aggregation for treating Alzheimer's disease

Nanometer-scale chirality has gained significant interest from different research fields due to its fundamental importance in nature and living matter. In this study, we design and synthesize chiral penicillamine-capped selenium nanoparticles (l-/d-Pen@Se NPs) that can act as a novel class of chiral amyloid-β (Aβ) inhibitors. In this work, d-Pen@Se NPs demonstrate higher inhibition efficiency, as well as ameliorate cognition and memory impairments. We used rat pheochromocytoma (PC12) cells to perform real-time cell analysis assay (RTCA) to probe the potential cytotoxicity of l-/d-Pen@Se NPs. At any given time point, the cell index decreases as d-Pen@Se NPs concentration increases, demonstrating a concentration-dependent cytotoxic effect on PC12 cells. In addition, d-Pen@Se NPs also reduced Zn²⁺-induced intracellular Aβ₄₀ fibrillation, while l-Pen@Se NPs did not. The histological analysis demonstrates that mice treated with d-Pen@Se NPs did not exhibit signs of in vivo systemic toxicity in major organs. Our findings are highly encouraging in terms of providing substantial evidence of the safety of chiral d-Pen@Se NPs for biomedical application. We expect that these results will be relevant for other chiral NPs for treatment of Alzheimer's disease and have broad implications in NP-based studies and applications.

Influence of reaction conditions on the self-assembly of the natural silk sericin protein

In the past years, the self-assembly of specific proteins has been paid more and more attention due to their significant role in human health and fabrication of new materials. In this article, we explore the effect of reaction conditions on the self-assembly of natural silk sericin protein, including the molecular weight and the concentration of sericin, pH, and metal ions in the reaction system. The results indicate that all these factors, especially species and concentration of metal ions, could influence the self-assembly process of the silk sericin protein. A series of assemblies with various morphologies can be fabricated by modulating the reaction condition. The article may provide some clue for the understanding of the protein self-assembly in the body and a method to fabricate new organic materials with different morphology. Microsc. Res. Tech. 80:298-304, 2017. © 2016 Wiley Periodicals, Inc.