Synergistic Inhibitory Effect of Peptide-Organic Coassemblies on Amyloid Aggregation

Celebrating 20 Years of NCNST: Innovation in Nanoscience and Nanotechnology

With the development of nanoscience and technology, it has become an essential part of various research directions, changing our way of life, such as advanced accurate manufacturing in nanotechnology that facilitates reducing chip sizes, progress made in health care via nanoscience that provides hope to patients, and so on. As the nation's flagship institution of nanoscience and technology in China, the National Center for Nanoscience and Technology, China (NCNST), established in December 2003, has played a crucial role in promoting cutting-edge technologies in the field of nanoscience and expediting interdisciplinary fusion. With a strong research team and state-of-the-art research equipment, NCNST currently carries out frontier research and world-class technology innovation, including nanosystems and hierarchical fabrication, biological effects of nanomaterials and nanosafety, standardization and measurements for nanotechnology, as well as theoretical simulations. Serving as one of the most prestigious institutions in nanoscience and nanotechnology in China, NCNST will continue to foster impactful international cooperation, cultivate young talents, and boost inspiring innovation.

Peptide-Functionalized Prussian Blue Nanomaterial for Antioxidant Stress and NIR Photothermal Therapy against Alzheimer's Disease

Excessive accumulations of reactive oxygen species (ROS) and amyloid-β (Aβ) protein are closely associated with the complex pathogenesis of Alzheimer's disease (AD). Therefore, approaches that synergistically exert elimination of ROS and dissociation of Aβ fibrils are effective therapeutic strategies for correcting the AD microenvironment. Herein, a novel near infrared (NIR) responsive Prussian blue-based nanomaterial (PBK NPs) is established with excellent antioxidant activity and photothermal effect. PBK NPs possess similar activities to multiple antioxidant enzymes, including superoxide dismutase, peroxidase, and catalase, which can eliminate massive ROS and relieve oxidative stress. Under the NIR irradiation, PBK NPs can generate local heat to disaggregate Aβ fibrils efficiently. By modifying CKLVFFAED peptide, PBK NPs display obvious targeting ability for blood-brain barrier penetration and Aβ binding. Furthermore, in vivo studies demonstrate that PBK NPs have outstanding ability to decompose Aβ plaques and alleviate neuroinflammation in AD mouse model. Overall, PBK NPs provide evident neuroprotection by reducing ROS levels and regulating Aβ deposition, and may accelerate the development of multifunctional nanomaterials for delaying the progression of AD.

Real-Time Fast Amyloid Seeding and Translocation of α-Synuclein with a Nanopipette

The detection to α-synuclein (αS) assemblies as a biomarker of synucleinopathies is an important challenge for further development of an early diagnosis tool. Here, we present proof of concept real-time fast amyloid seeding and translocation (RT-FAST) based on a nanopipette that combines in one unique system a reaction vessel to accelerate the seed amplification and nanopore sensor for single-molecule αS assembly detection. RT-FAST allows the detection of the presence αS seeds WT and A53T variant in a given sample in only 90 min by adding a low quantity (35 μL at 100 nM) of recombinant αS for amplification. It also shows cross-seeding aggregation by adding mixing seeds A53T with WT monomers. Finally, we establish the dependence between the capture rate of aggregates by the nanopore sensor and the initial seed concentration from 200 pM to 2 pM, which promises further development toward a quantitative analysis of the initial seed concentration.

High efficiency and related mechanism of Au(RC) nanoclusters on disaggregating Aβ fibrils

Revealing the disaggregating mechanism of amyloids fibrils under nanomaterials action is a key issue for their successful future use in therapy of neurodegenerative and overall amyloid-related diseases. Herein a gold nanocluster stabilized by Arg-Cys dipeptide (Au(RC)NCs) was synthesized to investigate its disaggregation activity toward Aβ fibrils by using Thioflavin-T (ThT) fluorescence assay and atomic force microscopy. It was demonstrated that Au(RC)NCs is very effective in disaggregating preformed Aβ fibrils, and characterized by the ultra-low apparent completely disaggregation concentration at the dose of 10 μg·mL^-1. A possible disaggregation mechanism based on Au(RC)NCs triggering the disassembly of Aβ fibrils into a dynamic equilibrium was proposed. The introduction of Au(RC)NCs with appropriate dose (5 μg·mL^-1) can trigger the disassemble process of mature Aβ fibrils into a critical state, at this very moment, if there is no more nano-disassembler, destruction of old Aβ fibrils and formation of new Aβ fibrils are thus in permanent dynamic equilibrium; in contrast, if there is more nano-disassembler (>10 μg·mL^-1), the dynamic equilibrium prefer to shift to the direction of Aβ further disassembly. Moreover, Au(RC)NCs with dosage over 10 μg·mL^-1 exhibited superb protection effect against Aβ-induced cytotoxicity in cell experiments. This study not only proposed a possible disassembly mechanism of amyloids fibrils under nanomaterials action, but also provide Au(RC)NCs as a promising high-effective nano-disassembler to disassemble unwanted amyloid aggregates.

Insights from computational analysis: how does the SARS-CoV-2 Delta (B.1.617.2) variant hijack ACE2 more effectively?

The SARS-CoV-2 Delta (B.1.617.2) variant was identified in India in October 2020, and it has quickly become the mainstream strain with strong toxicity and spread, posing great challenges to epidemic...

A Ratiometric Fluorescent Conjugated Oligomer for Amyloid β Recognition, Aggregation Inhibition, and Detoxification

The sensitive recognition and effective inhibition of toxic amyloid β protein (Aβ) aggregates play a critical role in early diagnosis and treatment of neurodegenerative diseases. In this work, a new conjugated oligo(fluorene-co-phenylene) (OFP) modified with 1,8-naphthalimide (NA) derivative OFP-NA-NO₂ is designed and synthesized as a ratiometric fluorescence probe for sensing Aβ, inhibiting the assembly of Aβ, and detoxicating the cytotoxicity of Aβ aggregates. In the presence of Aβ, the active ester group on the side chain of OFP-NA-NO₂ can covalently react with the amino group on Aβ, effectively inhibiting the formation of Aβ aggregates and degrading the preformed fibrils. In this case, the fluorescence intensity ratio of NA to OFP (I_NA /I_OFP ) increases greatly. The detection limit is calculated to be 89.9 nM, presenting the most sensitive ratiometric recognition of Aβ. Interestingly, OFP-NA-NO₂ can dramatically recover the cell viability of PC-12 and restore the Aβ-clearing ability of microglia. Therefore, this ratiometric probe exhibits the targeted recognition of Aβ, effective inhibition of Aβ aggregates, and detox effect, which is potential for early diagnosis and treatment of neurodegenerative diseases.

Interfacial Interactions within Amyloid Protein Corona Based on 2D MoS2 Nanosheets

The interfacial interaction within the amyloid protein corona based on MoS₂ nanomaterial is crucial, both for understanding the biological effects of MoS₂ nanomaterial and the evolution of amyloid diseases. The specific nano-bio interface phenomenon of human islet amyloid peptide (hIAPP) and MoS₂ nanosheet was investigated by using theoretical and experimental methods. The MoS₂ nanosheet enables the attraction of hIAPP monomer, dimer, and oligomer on its surface through van der Waals forces. Especially, the means of interaction between two hIAPP peptides might be changed by MoS₂ nanosheet. In addition, it is interesting to find that the hIAPP oligomer can stably interact with the MoS₂ nanosheet in one unique "standing" binding mode with an entire exposed β-sheet surface. All the interaction modes on the surface of MoS₂ nanosheet can be the essence of amyloid protein corona that may provide the venue to facilitate the fibrillation of hIAPP proteins. Further, it was verified experimentally that MoS₂ nanosheets could accelerate the fibrillation of hIAPP at a certain concentration mainly based on the newly formed nano-bio interface. In general, our results provide insight into the molecular interaction mechanism of the nano-bio interface within the amyloid protein corona, and shed light on the pathway of amyloid protein aggregation that is related to the evolution of amyloid diseases.

Unexpected Function of a Heptapeptide-Conjugated Zwitterionic Polymer that Coassembles into β-Amyloid Fibrils and Eliminates the Amyloid Cytotoxicity

Fibrillogenesis of amyloid β-protein (Aβ) is pathologically associated with Alzheimer's disease (AD), so modulating Aβ aggregation is crucial for AD prevention and treatment. Herein, a zwitterionic polymer with short dimethyl side chains (pID) is synthesized and conjugated with a heptapeptide inhibitor (Ac-LVFFARK-NH₂, LK7) to construct zwitterionic polymer-inhibitor conjugates for enhanced inhibition of Aβ aggregation. However, it is unexpectedly found that the LK7@pID conjugates remarkably promote Aβ fibrillization to form more fibrils than the free Aβ system but effectively eliminate Aβ-induced cytotoxicity. Such an unusual behavior of the LK7@pID conjugates is unraveled by extensive mechanistic studies. First, the hydrophobic environment within the assembled micelles of LK7@pID promotes the hydrophobic interaction between Aβ molecules and LK7@pID, which triggers Aβ aggregation at the very beginning, making fibrillization occur at an earlier stage. Second, in the aggregation process, the LK7@pID micelles disassemble by the intensive interactions with Aβ, and LK7@pID participates in the fibrillization by being embedded in the Aβ fibrils, leading to the formation of hybrid and heterogeneous fibrillar aggregates with a different structure than normal Aβ fibrils. This unique Trojan horse-like feature of LK7@pID conjugates has not been observed for any other inhibitors reported previously and may shed light on the design of new modulators against β-amyloid cytotoxicity.

Halogen bonding controlled 2D self-assembled polymorphism of regioisomeric thienophenanthrene derivatives by coadsorption

5,10-BTD-C14 molecules display self-assembled polymorphism in different bromo-hydrocarbons with different solution concentrations at the liquid/solid interface.

Emodin inhibits aggregation of amyloid-β peptide 1-42 and improves cognitive deficits in Alzheimer's disease transgenic mice

Aggregation of amyloid-β peptide 1-42 (Aβ42) initiates the onset of Alzheimer's disease (AD), and all the drugs designed to attenuate AD have failed in clinical trials. Emodin reduces levels of β-amyloid, tau aggregation, oxidative stress, and inflammatory response, demonstrating AD therapeutic potential, whereas its effect on the accumulation of the amyloid-β protein is not well understood. In this work, we investigated emodin activity on Aβ aggregation using a range of biochemical, biophysical, and cell-based approaches. We provide evidence to suggest that emodin blocks Aβ42 fibrillogenesis and Aβ-induced cytotoxicity, displaying a greater effect than that of curcumin. Through adopting three short peptides (Aβ1-16, Aβ17-33, and Aβ28-42), it was proven that emodin interacts with the Leu17-Gly33 sequence. Furthermore, our findings indicated that Val18 and Phe19 in Aβ42 are the target residues with which emodin interacts according amino acid mutation experiments. When fed to 8-month-old B6C3-Tg mice for 2 months, high-dose emodin ameliorates cognitive impairment by 60%-70%. Pathological results revealed that levels of Aβ deposition in the brains of AD mice treated with a high dose of emodin decreased by 50%-70%. Therefore, our study indicates that emodin may represent a promising drug for AD treatment.

Latent Models of Molecular Dynamics Data: Automatic Order Parameter Generation for Peptide Fibrillization

Variational autoencoders are artificial neural networks with the capability to reduce highly dimensional sets of data to smaller dimensional, latent representations. In this work, these models are applied to molecular dynamics simulations of the self-assembly of coarse-grained peptides to obtain a singled-valued order parameter for amyloid aggregation. This automatically learned order parameter is constructed by time-averaging the latent parametrizations of internal coordinate representations and compared to the nematic order parameter which is commonly used to study ordering of similar systems in literature. It is found that the latent space value provides more tailored insight into the aggregation mechanism's details, correctly identifying fibril formation in instances where the nematic order parameter fails to do so. A means is provided by which the latent space value can be analyzed so that the major contributing internal coordinates are identified, allowing for a direct interpretation of the latent space order parameter in terms of the behavior of the system. The latent model is found to be an effective and convenient way of representing the data from the dynamic ensemble and provides a means of reducing the dimensionality of a system whose scale exceeds molecular systems so-far considered with similar tools. This bypasses a need for researcher speculation on what elements of a system best contribute to summarizing major transitions and suggests latent models are effective and insightful when applied to large systems with a diversity of complex behaviors.

A Biocompatible Second Near-Infrared Nanozyme for Spatiotemporal and Non-Invasive Attenuation of Amyloid Deposition through Scalp and Skull

Phototherapy, such as photodynamic therapy and photothermal therapy, holds great potential for modulation of Alzheimer's β-amyloid (Aβ) self-assembly. Unfortunately, current works for phototherapy of Alzheimer's disease (AD) are just employing either visible or first near-infrared (NIR-I) light with limited tissue penetration, which can not avoid damaging nearby normal tissues of AD patients through the dense skull and scalp. To overcome the shortcomings of AD phototherapy, herein we report an amyloid targeting, N-doped three-dimensional mesoporous carbon nanosphere (KD8@N-MCNs) as a second near-infrared (NIR-II) PTT agent. This makes it possible for photothermal dissociation of Aβ aggregates through the scalp and skull in a NIR-II window without hurting nearby normal tissues. Besides, KD8@N-MCNs have both superoxide dismutase and catalase activities, which can scavenge intracellular superfluous reactive oxygen species and alleviate neuroinflammation in vivo. Furthermore, KD8@N-MCNs efficiently cross the blood-brain barrier owing to the covalently grafted target peptides of KLVFFAED on the nanosphere surface. In vivo studies demonstrate that KD8@N-MCNs decrease Aβ deposits, ameliorate memory deficits, and alleviate neuroinflammation in the 3xTg-AD mouse model. Our work provides a biocompatible and non-invasive way to attenuate AD-associated pathology.

Nontoxic Black Phosphorus Quantum Dots Inhibit Insulin Amyloid Fibrillation at an Ultralow Concentration

Amyloid are protein aggregates formed by cross β structures assemblies. Inhibiting amyloid aggregation or facilitating its disassembly are considered to be two major effective therapeutic strategies in diseases involving peptide or protein fibrillation such Alzheimer's disease or diabetes. Using thioflavin-T fluorescence, far-UV circular dichroism spectroscopy, and atomic force microscopy, we found nontoxic and biocompatible black phosphorus quantum dots (BPQDs) appear to have an exceptional capacity to inhibit insulin aggregation and to disassemble formed mature fibrils, even at an ultralow concentration (100 ng/mL). The inhibition of fibrillation persists at all stages of insulin aggregation and increases PC12 cells survival when exposed to amyloid fibrils. Molecular dynamics simulations suggest that BPQDs are able to stabilize the α-helix structure of insulin and obliterate the β-sheet structure to promote the fibril formation. These characteristics make BPQDs be promising candidate in preventing amyloidosis, disease treatment, as well as in the storage and processing of insulin.

•

BPQDs inhibit insulin amyloid fibrillation at an ultralow concentration

•

BPQDs can depolymerize protofibrils and even mature fibers

•

BPQDs inhibit aggregation mainly by van der Waals' force and hydrophobic interaction

•

BPQDs are biocompatible and can reduce insulin fibrils-induced cytotoxicity

Mitochondria-targeted TPP-MoS2 with dual enzyme activity provides efficient neuroprotection through M1/M2 microglial polarization in an Alzheimer's disease model

Alzheimer's disease (AD) is one of the most common age-associated brain diseases and is induced by the accumulation of amyloid beta (Aβ) and oxidative stress. Many studies have focused on eliminating Aβ by nanoparticle affinity; however, nanoparticles are taken up mainly by microglia rather than neurons, leading poor control of AD. Herein, mitochondria-targeted nanozymes known as (3-carboxypropyl)triphenyl-phosphonium bromide-conjugated 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-2000]-functionalized molybdenum disulfide quantum dots (TPP-MoS₂ QDs) were designed. TPP-MoS₂ QDs mitigate Aβ aggregate-mediated neurotoxicity and eliminate Aβ aggregates in AD mice by switching microglia from the proinflammatory M1 phenotype to the anti-inflammatory M2 phenotype. TPP-MoS₂ QDs cross the blood-brain barrier, escape from lysosomes, target mitochondria and exhibit the comprehensive activity of a bifunctional nanozyme, thus preventing spontaneous neuroinflammation by regulating the proinflammatory substances interleukin-1β, interleukin-6 and tumor necrosis factors as well as the anti-inflammatory substance transforming growth factor-β. In contrast to the low efficacy of eliminating Aβ by nanoparticle affinity, the present study provides a new pathway to mitigate AD pathology through mitochondria-targeted nanozymes and M1/M2 microglial polarization.

Au23(CR)14 nanocluster restores fibril Aβ's unfolded state with abolished cytotoxicity and dissolves endogenous Aβ plaques

The misfolding of amyloid-β (Aβ) peptides from the natural unfolded state to β-sheet structure is a critical step, leading to abnormal fibrillation and formation of endogenous Aβ plaques in Alzheimer's disease (AD). Previous studies have reported inhibition of Aβ fibrillation or disassembly of exogenous Aβ fibrils in vitro. However, soluble Aβ oligomers have been reported with increased cytotoxicity; this might partly explain why current clinical trials targeting disassembly of Aβ fibrils by anti-Aβ antibodies have failed so far. Here we show that Au₂₃(CR)₁₄ (a new Au nanocluster modified by Cys-Arg (CR) dipeptide) is able to completely dissolve exogenous mature Aβ fibrils into monomers and restore the natural unfolded state of Aβ peptides from misfolded β-sheets. Furthermore, the cytotoxicity of Aβ₄₀ fibrils when dissolved by Au₂₃(CR)₁₄ is fully abolished. More importantly, Au₂₃(CR)₁₄ is able to completely dissolve endogenous Aβ plaques in brain slices from transgenic AD model mice. In addition, Au₂₃(CR)₁₄ has good biocompatibility and infiltration ability across the blood-brain barrier. Taken together, this work presents a promising therapeutics candidate for AD treatment, and manifests the potential of nanotechnological approaches in the development of nanomedicines.

Patterning Porous Networks through Self-Assembly of Programmed Biomacromolecules

Two-dimensional (2D) porous networks are of great interest for the fabrication of complex organized functional materials for potential applications in nanotechnologies and nanoelectronics. This review aims at providing an overview of bottom-up approaches towards the engineering of 2D porous networks by using biomacromolecules, with a particular focus on nucleic acids and proteins. The first part illustrates how the advancements in DNA nanotechnology allowed for the attainment of complex ordered porous two-dimensional DNA nanostructures, thanks to a biomimetic approach based on DNA molecules self-assembly through specific hydrogen-bond base pairing. The second part focuses the attention on how polypeptides and proteins structural properties could be used to engineer organized networks templating the formation of multifunctional materials. The structural organization of all examples is discussed as revealed by scanning probe microscopy or transmission electron microscopy imaging techniques.

Multifunctional inhibitors of β-amyloid aggregation based on MoS2/AuNR nanocomposites with high near-infrared absorption

Recent advances in nanotechnology have developed a lot of opportunities for biological applications. In this work, multifunctional MoS2/AuNR nanocomposites with unique high NIR absorption were designed via combining MoS2 nanosheets and gold nanorods (AuNRs). The nanocomposites were synthesized through electrostatic self-assembly and showed high stability and good biocompatibility. Then they were used to modulate the aggregation of amyloid-β peptides, destabilize mature fibrils under NIR irradiation, and eliminate Aβ-induced ROS against neurotoxicity. The inhibition and destabilization effects were confirmed by Thioflavin T (ThT) fluorescence assay and transmission electron microscopy (TEM). Cell viability assay and ROS assay revealed that MoS2/AuNR nanocomposites could alleviate Aβ-induced oxidative stress and cell toxicity. More importantly, both MoS2 nanosheets and AuNRs can be used as NIR photothermal agents, MoS2/AuNR nanocomposites have enhanced ability of disrupting Aβ fibrils and improved cell viability by generating local heat under low power NIR irradiation. Our results provide new insights into the design of new multifunctional systems for the treatment of amyloid-related diseases.

Unorthodox Combination of Cation-π and Charge-Transfer Interactions within a Donor-Acceptor Pair

Cation-π and charge-transfer (CT) interactions are ubiquitous in nature and involved in several biological processes. Although the origin of both the interactions in isolated pairs has extensively been studied, CT interactions are more prominent in supramolecular chemistry. Involvement of cation-π interactions in the preparation of advanced functional soft materials is uncommon. Moreover, a combination of these two interactions within a pair of electron donor (D) and acceptor (A) is uncharted. Here, we present a rational design to incorporate a combination of these two interactions within a D-A pair. A pyrene-peptide conjugate exhibits a combination of cation-π and CT interactions with a cationic naphthalenediimide (NDI) molecule in water. Nuclear Overhauser effect spectroscopy NMR along with other techniques and density functional theory calculations reveal the involvement of these interactions. The π-planes of pyrene and NDI adopt an angle of 56° to satisfy both the interactions, whereas β-sheet formation by the peptide sequence facilitates self-assembly. Notably, the binary system forms a self-supporting hydrogel at a higher concentration. The hydrogel shows efficient self-healing and injectable property. The hydrogel retains its thixotropic nature even at an elevated temperature. Broadly, we demonstrate a pathway that should prove pertinent to various areas, ranging from understanding biological assembly to peptide-based functional soft materials.

Molecular dynamics simulations reveal the mechanism of graphene oxide nanosheet inhibition of Aβ1–42 peptide aggregation

Graphene oxide nanosheets inhibit Aβ1–42 aggregation by weakening inter-peptide interactions and reducing β-sheet contents mostly via salt bridge, hydrogen bonding and cation–π interactions with charged residues.

Deformation of stable and toxic hIAPP oligomers by liposomes with distinct nanomechanical features and reduced cytotoxicity

Nanoliposomes can induce hIAPP oligomers to undergo fibrillation with distinct mechanical properties and reduced cytotoxicity.

Peptide Self-Assembly and Its Modulation: Imaging on the Nanoscale

This chapter intends to review the progress in obtaining site-specific structural information for peptide assemblies using scanning tunneling microscopy. The effects on assembly propensity due to mutations and modifications in peptide sequences, small organic molecules and conformational transitions of peptides are identified. The obtained structural insights into the sequence-dependent assembly propensity could inspire rational design of peptide architectures at the molecular level.

Evaluation of the photo-degradation of Alzheimer's amyloid fibrils with a label-free approach

Degradation of amyloid-β (Aβ) aggregates has been considered as an attractive therapeutic and preventive strategy against Alzheimer's disease (AD). However, an in situ, real-time, and label-free technique is still lacking to understand the degradation process of Aβ aggregates. In this work, we developed a novel method to quantitatively evaluate the degradation of Aβ fibrils by photoactive meso-tetra(4-sulfonatophenyl)porphyrin under UV irradiation with quartz crystal microbalance (QCM).

Free Energy Landscape for Alpha-Helix to Beta-Sheet Interconversion in Small Amyloid Forming Peptide under Nanoconfinement

Understanding the mechanism of fibrillization of amyloid forming peptides could be useful for the development of therapeutics for Alzheimer's disease (AD). Taking this standpoint, we have explored in this work the free energy profile for the interconversion of monomeric and dimeric forms of amyloid forming peptides into different secondary structures namely beta-sheet, helix, and random coil in aqueous solution using umbrella sampling simulations and density functional theory calculations. We show that the helical structures of amyloid peptides can form β sheet rich aggregates through random coil conformations in aqueous condition. Recent experiments ( Chem. Eur. J. 2018, 24, 3397-3402 and ACS Appl. Mater. Interfaces 2017, 9, 21116-21123) show that molybdenum disulfide nanosurface and nanoparticles can reduce the fibrillization process of amyloid beta peptides. We have unravelled the free energy profile for the interconversion of helical forms of amyloid forming peptides into beta-sheet and random coil in the presence of a two-dimensional nanosurface of MoS₂. Results indicate that the monomer and dimeric forms of the peptides adopt the random coil conformation in the presence of MoS₂ while the helical form is preferable for the monomeric form and that the beta-sheet and helix forms are the preferable forms for dimers in aqueous solution. This is due to strong interaction with MoS₂ and intramolecular hydrogen bonds of random coil conformation. The stabilization of random coil conformation does not lead to a β sheet like secondary structure for the aggregate. Thus, the confinement of MoS₂ promotes deaggregation of amyloid beta peptides rather than aggregation, something that could be useful for the development of therapeutics for AD.

SynAggreg: A Multifunctional High-Throughput Technology for Precision Study of Amyloid Aggregation and Systematic Discovery of Synergistic Inhibitor Compounds

Numerous proteins can coalesce into amyloid self-assemblies, which are responsible for a class of diseases called amyloidoses, but which can also fulfill important biological functions and are of great interest for biotechnology. Amyloid aggregation is a complex multi-step process, poorly prone to detailed structural studies. Therefore, small molecules interacting with amyloids are often used as tools to probe the amyloid aggregation pathway and in some cases to treat amyloidoses as they prevent pathogenic protein aggregation. Here, we report on SynAggreg, an in vitro high-throughput (HT) platform dedicated to the precision study of amyloid aggregation and the effect of modulator compounds. SynAggreg relies on an accurate bi-fluorescent amyloid-tracer readout that overcomes some limitations of existing HT methods. It allows addressing diverse aspects of aggregation modulation that are critical for pathomechanistic studies, such as the specificity of compounds toward various amyloids and their effects on aggregation kinetics, as well as the co-assembly propensity of distinct amyloids and the influence of prion-like seeding on self-assembly. Furthermore, SynAggreg is the first HT technology that integrates tailored methodology to systematically identify synergistic compound combinations-an emerging strategy to improve fatal amyloidoses by targeting multiple steps of the aggregation pathway. To this end, we apply analytical combinatorial scores to rank the inhibition efficiency of couples of compounds and to readily detect synergism. Finally, the SynAggreg platform should be suited for the characterization of a broad class of amyloids, whether of interest for drug development purposes, for fundamental research on amyloid functions, or for biotechnological applications.

Nanotribological Study of Supramolecular Template Networks Induced by Hydrogen Bonds and van der Waals Forces

Nanotribology has been given increasing attention by researchers in pursuing the nature of friction. In the present work, an approach that combines the supramolecular assembly and nanotribology is introduced. Herein, the nanotribological study was carried out on seven supramolecular template networks [namely, hydrogen bond induced tricarboxylic acids and van der Waals force induced hexaphenylbenzene (HPB) derivatives]. The template networks, as well as the host-guest assemblies of template molecules induced by different forces, were constructed on the highly oriented pyrolytic graphite (HOPG) surface and explicitly characterized using scanning tunneling microscopy (STM). Meanwhile, the nanotribological properties of the template networks were measured using atomic force microscopy (AFM). Together with the theoretical calculation using the density functional theory (DFT) method, it was revealed that the friction coefficients were positively correlated with the interaction strength. The frictional energy dissipation mainly derives from both the intermolecular interaction energy and the interaction energy between molecules and the substrate. The efforts not only help us gain insight into the competitive mechanisms of hydrogen bond and van der Waals force in supramolecular assembly but also shed light on the origin of friction and the relationship between the assembly structures and the nanotribological properties at the molecular level.

Supramolecular Assemblies on Surfaces: Nanopatterning, Functionality, and Reactivity

Understanding how molecules interact to form large-scale hierarchical structures on surfaces holds promise for building designer nanoscale constructs with defined chemical and physical properties. Here, we describe early advances in this field and highlight upcoming opportunities and challenges. Both direct intermolecular interactions and those that are mediated by coordinated metal centers or substrates are discussed. These interactions can be additive, but they can also interfere with each other, leading to new assemblies in which electrical potentials vary at distances much larger than those of typical chemical interactions. Earlier spectroscopic and surface measurements have provided partial information on such interfacial effects. In the interim, scanning probe microscopies have assumed defining roles in the field of molecular organization on surfaces, delivering deeper understanding of interactions, structures, and local potentials. Self-assembly is a key strategy to form extended structures on surfaces, advancing nanolithography into the chemical dimension and providing simultaneous control at multiple scales. In parallel, the emergence of graphene and the resulting impetus to explore 2D materials have broadened the field, as surface-confined reactions of molecular building blocks provide access to such materials as 2D polymers and graphene nanoribbons. In this Review, we describe recent advances and point out promising directions that will lead to even greater and more robust capabilities to exploit designer surfaces.

Multicomponent peptide assemblies

Self-assembled peptide nanostructures have been increasingly exploited as functional materials for applications in biomedicine and energy. The emergent properties of these nanomaterials determine the applications for which they can be exploited. It has recently been appreciated that nanomaterials composed of multicomponent coassembled peptides often display unique emergent properties that have the potential to dramatically expand the functional utility of peptide-based materials. This review presents recent efforts in the development of multicomponent peptide assemblies. The discussion includes multicomponent assemblies derived from short low molecular weight peptides, peptide amphiphiles, coiled coil peptides, collagen, and β-sheet peptides. The design, structure, emergent properties, and applications for these multicomponent assemblies are presented in order to illustrate the potential of these formulations as sophisticated next-generation bio-inspired materials.

Synergistic Inhibitory Effect of GQDs-Tramiprosate Covalent Binding on Amyloid Aggregation

Inhibiting the amyloid aggregation is considered to be an effective strategy to explore possible treatment of amyloid-related diseases including Alzheimer's disease, Parkinson's disease, and type II diabetes. Herein, a new high-efficiency and low-cytotoxicity Aβ aggregation inhibitors, GQD-T, was designed through the combination of two Aβ aggregation inhibitors, graphene quantum dots (GQDs) and tramiprosate. GQD-T showed the capability of efficiently inhibiting the aggregation of Aβ peptides and rescuing Aβ-induced cytotoxicity due to the synergistic effect of the GQDs and tramiprosate. In addition, the GQD-T has the characteristics of low toxicity and great biocompatibility. It is believed that GQD-T may be a potential candidate for an Alzheimer's drug and this work provides a new strategy for exploring Aβ peptide aggregation inhibitors.

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.

Molybdenum Disulfide Nanoparticles as Multifunctional Inhibitors against Alzheimer's Disease

The complex pathogenic mechanisms of Alzheimer's disease (AD) include the aggregation of β-amyloid peptides (Aβ) into oligomers or fibrils as well as Aβ-mediated oxidative stress, which require comprehensive treatment. Therefore, the inhibition of Aβ aggregation and free-radical scavenging are essential for the treatment of AD. Nanoparticles (NPs) have been found to influence Aβ aggregation process in vitro. Herein, we report the inhibition effects of molybdenum disulfide (MoS₂) NPs on Aβ aggregation. Polyvinylpyrrolidone-functionalized MoS₂ NPs were fabricated by a pulsed laser ablation method. We find that MoS₂ NPs exhibit multifunctional effects on Aβ peptides: inhibiting Aβ aggregation, destabilizing Aβ fibrils, alleviating Aβ-induced oxidative stress, as well as Aβ-mediated cell toxicity. Moreover, we show that MoS₂ NPs can block the formation of the Ca²⁺ channel induced by Aβ fibrils in the cell membrane for the first time. Thus, these observations suggest that MoS₂ NPs have great potential for a multifunctional therapeutic agent against amyloid-related diseases.

Diphenylalanine as a Reductionist Model for the Mechanistic Characterization of β-Amyloid Modulators

The phenomenon of protein aggregation into amyloid fibrils is associated with a large number of major diseases of unrelated etiology. Unraveling the mechanism of amyloid self-assembly and identifying therapeutic directions to control this process are of utmost importance. Research in this field has been hampered by several challenges, including reproducibility, low protein purification yields, and the inherent aggregation propensity of amyloidogenic proteins, making them extremely difficult to study. Herein, on the basis of the similarity in the assembly mechanism, as well as the physical, chemical, and biological characteristics, of diphenylalanine nanostructures and aromatic amino acid containing amyloid fibrils, we report a simple, yet robust peptide-based platform that could be used for screening of small molecules potentially capable of interfering with the aggregation process and for mechanistic exploration of their mode of action. The system was validated using four small-molecule inhibitors, and the effect was examined via turbidity assay, thioflavin T fluorescence, and electron microscopy. The aggregation profile of diphenylalanine was very similar to that of β-amyloid polypeptide in the presence of the modulators. Rosmarinic acid emerged as an extremely potent inhibitor and a destabilizer of the aggregates. The effect of stoichiometric variation of rosmarinic acid on the process of destabilization was also probed using a microfluidic technique. Finally, the formation of equimolar complexes of diphenylalanine and inhibitors was detected using mass spectrometry. This approach not only provides a system for high-throughput screening of possible inhibitor molecules from larger libraries of modulators, but is also highly useful for understanding the mechanistic aspects of the interactions leading to the process of inhibition.

Fluorine Functionalized Graphene Quantum Dots as Inhibitor against hIAPP Amyloid Aggregation

Fibrillar deposits of the human islet amyloid polypeptide (hIAPP) are considered as a root of Type II diabetes mellitus. Fluorinated graphene quantum dots (FGQDs) are new carbon nanomaterials with unique physicochemical properties containing highly electronegative F atoms. Herein we report a single step synthesis method of FGQDs with an inhibitory effect on aggregation and cytotoxicity of hIAPP in vitro. Highly fluorescent and water dispersible FGQDs, less than 3 nm in size, were synthesized by the microwave-assisted hydrothermal method. Efficient inhibition capability of FGQDs to amyloid aggregation was demonstrated. The morphologies of hIAPP aggregates were observed to change from the entangled long fibrils to short thin fibrils and amorphous aggregates in the presence of FGQDs. In thioflavin T fluorescence analysis, inhibited aggregation with prolonged lag time and reduced fluorescence intensity at equilibrium were observed when hIAPP was incubated together with FGQDs. Circular dichroism spectrum results reveal that FGQDs could inhibit conformational transition of the peptide from native structure to β-sheets. FGQDs could also rescue the cytotoxicity of INS-1 cells induced by hIAPP in a dose dependent manner. This study could be beneficial for design and preparation of inhibitors for amyloids, which is important for prevention and treatment of amyloidosis.

Interfacial assembly structures and nanotribological properties of saccharic acids

The larger friction of the successfully constructed assembly of saccharic acid indicates the higher potential energy barrier at the interface.