Formation of Functionalized Nanowires by Control of Self‐Assembly Using Multiple Modified Amyloid Peptides

Amyloid peptides have great potential as building blocks in the creation of functional nanowires due to their natural ability to self‐assemble into nanofibrillar structures and because they can be easily modified with various functional groups. However, significant modifications of an amyloid peptide generally alter its self‐assembly property, making it difficult to construct functionalized fibrils with a desired structure and function. In this study, a very effective method to overcome this problem is demonstrated by using our structure‐controllable amyloid peptides (SCAPs) terminated with a three‐amino‐acid‐residue cap. The method consists on mixing two or more structurally related amyloid peptides with a fraction of modified SCAPs which co‐assemble into a fibril. This SCAP‐mixing method provides remarkable control over the self‐assembly process both on the small oligomers level and the macroscopic fibrils level. Furthermore, it is shown that the modified peptides imbedded in the resulting fibril can subsequently be functionalized to generate nanowires with the desired properties, highlighting the importance of this SCAP method for nanotechnology applications.     

Histological study of experimental murine AA amyloidosis

The localization of amyloid fibril components and the cells related to the formation and resorption of the fibrils are still controversial. We conducted a time-kinetic study to analyse the process of amyloid fibril deposition in the spleen of an AA amyloidosis animal model immunohistochemically. Murine AA amyloidosis was induced by an emulsion injection composed of Freund's complete adjuvant and Mycobacterium butyricum. The serum amyloid A level was the highest at 3 days after the induction and gradually decreased. The amyloid deposition was first detected in extracellular spaces in the marginal zone of the spleen at 7 days after induction. F4/80 positive red pulp macrophages increased in number after the induction and accumulated near the amyloid deposition areas. Amyloid P component (APC) and chondroitin sulphate proteoglycan (CSPG), which are composed of amyloid fibril, were detected in the cytoplasm of F4/80 positive red pulp macrophages and ER-TR9 positive marginal zone macrophages, respectively, then localized in the amyloid deposition areas. APC was also localized in CSPG positive and F4/80 negative cells, which might be fibroblasts at 3 days. These results suggest a close association of APC positive/ER-TR9 positive macrophages and APC positive/CSPG positive fibroblasts in the formation of amyloid fibrils and F4/80 positive macrophages with the resorption of fibrils.     

Structure and formation of the twisted plywood pattern of collagen fibrils in rat lamellar bone

This study was designed to elucidate details of the structure and formation process of the alternate lamellar pattern known to exist in lamellar bone. For this purpose, we examined basic internal lamellae in femurs of young rats by transmission and scanning electron microscopy, the latter employing two different macerations with NaOH at concentrations of 10 and 24%. Observations after the maceration with 10% NaOH showed that the regular and periodic rotation of collagen fibrils caused an alternation between two types of lamellae: one consisting of transversely and nearly transversely cut fibrils, and the other consisting of longitudinally and nearly longitudinally cut fibrils. This finding confirms the consistency of the twisted plywood model. The maceration method with 24% NaOH removed bone components other than cells, thus allowing for three-dimensional observations of osteoblast morphology. Osteoblasts extended finger-like processes paralleling the inner bone surface, and grouped in such a way that, within a group, the processes arranged in a similar direction. Transmission electron microscopy showed that newly deposited fibrils were arranged alongside these processes. For the formation of the alternating pattern, our findings suggest that: (1) osteoblasts control the collagen fibril arrangement through their finger-like process position; (2) osteoblasts behave similarly within a group; (3) osteoblasts move their processes synchronously and periodically to promote alternating different fibril orientation; and (4) this dynamic sequential deposition of fibrils results in the alternate lamellar (or twisted plywood) pattern.     

Design and Engineering of Amyloid Aggregation-Prone Fragments and Their Antimicrobial Conjugates with Multi-Target Functionality

Amyloid aggregation and microbial infection are considered major risk factors for neurodegeneration and neuroinflammation in protein misfolding diseases (PMDs), including Alzheimer's disease (AD) and Type 2 diabetes (T2D). However, current amyloid inhibitors are mostly limited to single-target prevention strategies against specific amyloid proteins or pathogenic microbes, leading to no success for clinical cures of PMDs. Here, a step-by-step strategy to design new, multi-target amyloid aggregation-prone fragments (APFs) and their APFs antimicrobial agent conjugates is proposed, capable of achieving the stepwise improved multifunctionality of amyloid inhibition, antimicrobial activity, and amyloid imaging. The two APFs of KLVFF from Aβ (associated with AD) and FGAIL from hIAPP (associated with T2D) with β-structure-forming property are selected and used as building block to construct a hybrid KLVFFGAIL peptide (K9) and a K9-AMC (7-amino-4-methylcoumarin) fluorescence conjugate, both of which have demonstrated the improved, multiple-target, sequence-independent functions to inhibit the aggregation of both Aβ and hIAPP, reduce both Aβ- and hIAPP-induced cell toxicity, prevent different microbial growth, and introduce fluorescence images for amyloid fibrils. The sequence-independent amyloid inhibition function of K9 and K9-AMC mainly stems from their cross-interactions with amyloid proteins via β-structure and aromatic interactions. This work provides a proof-of-concept example to not only explore a new family of APFs as antimicrobial and anti-amyloid drugs for the therapeutic potential of PMDs, but also better understand the pathological links between protein aggregation and microbial infection in PMDs along the gut–brain axis.     

Amyloid Fibrils form Hybrid Colloidal Gels and Aerogels with Dispersed CaCO3 Nanoparticles

New hybrid colloidal gels are reported formed by amyloid fibrils and CaCO₃ nanoparticles (CaNPs), with Ca²⁺ as charge screening ions and CaNPs as physical crosslinking agents to establish and stabilize the network. The gel is characterized by rheological measurements and diffusing wave spectroscopy, complemented by microscopic observations using transmission and scanning electron microscopy. The hybrid colloidal gels show a two orders of magnitude improved gel strength at significantly shorter gelation times compared to previous calcium ion‐induced amyloid fibril gels. Supercritical CO₂‐dried colloidal aerogels allow demonstrating that amyloid fibrils, combined with smaller (higher specific surface area) CaNPs, constitute a denser fibrils network, resulting in stronger gels. By varying the amyloid fibril concentration and the CaNPs size and concentration, the complete phase diagram is mapped out. This enables identifying the sol–gel phase transition and a window for gel formation, which widens with increasing CaNPs size. Finally pH responsiveness and self‐healing properties of this hybrid colloidal gel are also demonstrated, making these systems a suitable candidate for biological applications.     

Ultra-Small ATP-Decorated Gold Nanoparticles for Targeting Amyloid Fibrils in Neurodegenerative Diseases

Ultrafine Gold nanoparticles (Au NPs) functionalized with various biomolecules constitute an alternative to antibodies as anti-amyloidogenic agents. However, generating stable ultrafine Au NPs with high surface activity is challenging. Here, the capacity of phosphate groups in biomolecules is used to stabilize Au NPs. The characteristics of Au NPs decorated with adenosine mono-, di-, and tri-phosphate are compared as well as adenosine and peptide nucleic acid-containing adenosine as controls. Among them, ATP-Au NPs are found to be superior having small size (2–4 nm) and stability (for several months) when analysed by spectroscopy and electron microscopy. Spectroscopy analysis also revealed that each ATP-stabilized Au NP is decorated with 7–8 molecules of ATP. ThT binding analysis and TEM imaging showed that the ATP-Au NPs efficiently prevented amyloid fibril formation in vitro by Aβ-42, α-Synuclein as well as by the Glucosylceramide metabolite, and disaggregated their pre-formed fibrils. NMR analysis revealed the interaction of the ATP-Au NPs with the amyloid fibrils. The ATP-Au NPs are safe toward cultured SH-SY5Y cells and when co-incubated with α-Synuclein amyloids inhibited their cytotoxicity and readily enter the cells to inhibit formation of amyloid fibrils within them. The results indicates the pharmacological potentials of ATP decorated Au NPs.     

Immunohistochemical detection of haem oxygenase in AA amyloidogenesis

Haem oxygenase (HO)-1, a rate-limiting enzyme in the degradation of haem, is increased in Alzheimer's disease and in inflammations such as AA amyloidosis. However, the specific association of HO-1 is poorly understood in AA amyloidosis. In this study, we designed the experiment to reveal the contribution and association of HO-1 in the spleen during experimental murine AA amyloidosis. Experimental murine AA amyloidosis was induced with injection of an emulsion consisting of Freund's complete adjuvant and Mycobacterium butyricum. The serum amyloid A level was highest on day 3. The distribution of cells containing iron, indicating an increase of HO-1 in the red pulp, was detected with Berlin blue staining. AA amyloid formation was immunohistochemically detected as a marker by chondroitin sulphate proteoglycan (CSPG), one of the components of AA amyloid fibrils. Immunolocalizations of HO-1 and CSPG indicated a conspicuous increase and scattering of positive cells in the red pulp of the spleen. Double positive cells were not detected. On day 7, amyloid deposition was detected with Congo red staining in the extracellular spaces in the marginal zone of the white pulp in the spleen and HO-1-positive cells accumulated near the amyloid deposition area. CSPG was detected within the cells and also localized in the amyloid deposition area. CSPG was still not localized in the HO-1-positive cells. Double positive cells of HO-1 and CSPG were localized in the red pulp and in the amyloid deposition area on day 14. X-ray microanalysis indicated the existence of iron in the electron-dense bodies of fibroblasts in the amyloid deposition areas. The fibroblasts extended amyloid fibrils into the extracellular spaces of the marginal zone. These results suggest that HO-1-positive fibroblasts, but not HO-1-positive macrophages, are associated with the late stage of amyloid fibril formation.     

Amyloid Directed Synthesis of Titanium Dioxide Nanowires and Their Applications in Hybrid Photovoltaic Devices

This paper reports β‐lactoglobulin amyloid protein fibrils directed synthesis of Titanium Dioxide (TiO₂) hybrid nanowires. Protein fibrils act as templates to generate closely packed TiO₂ nanoparticles on the surface of the fibrils using titanium (IV) bis (ammonium lactato) dihydroxide (TiBALDH) as precursor, resulting in the TiO₂–coated amyloid hybrid nanowires. These amyloid fibrils also exhibit complexation with a luminescent water‐soluble semiconductive polythiophene (P3HT). TiO₂ nanowires behave as electron acceptor while, P3HT as electron donor. In this way, amyloid‐TiO₂ hybrid nanowires can serve in heterojunction photovoltaic devices. To demonstrate this, a photovoltaic active layer is prepared by spin coating the blended mixture of polythiophene‐coated fibrils and amyloid‐TiO₂ hybrid nanowires. The current–voltage characteristics of these photovoltaic devices exhibit excellent fill factor of 0.53, photovoltaic current density of 3.97 mA·cm^?2 and power conversion efficiency of 0.72%, highlighting a possible future role for amyloid‐based templates in donor–acceptor devices, organic electronics and hybrid solar cells.     

基于负染－电镜的Aβ体外聚集表征测试要点分析

本文应用电镜负染色技术,对阿尔茨海默病（ Alzheimer′s disease, AD）中所涉及的β淀粉样肽（β?amyloid peptide,Aβ）的聚集规律进行了分析。通过对样品的浓度、pH值、温度和时间等设置系列梯度,以及调整负染试剂的种类、浓度和染色时间,优化了Aβ寡聚体样品制备以及电镜观察的最佳条件,获得了清晰的Aβ纤维图像并用以估算纤维长度。实验结果表明：经过六氟异丙醇给予单体化处理,并溶于无水二甲基亚砜（ DMSO）的Aβ（100μmol·L－1）,在pH7?2的PBS中4℃孵育24 h,Aβ寡聚体形态清晰,且Aβ42寡聚体比Aβ40寡聚体聚集趋势更明显。在pH 8?0的硼酸缓冲液中,Aβ42（40μmol·L－1）在37℃孵育72 h后,纤维形成明显;而Aβ纤维样品经过煮沸后再制备负染样品,所得电镜图像更为清晰,便于对纤维长度和结构进一步分析。因此电镜负染色技术,可作为一种快捷,直观的Aβ体外聚集形貌表征的质控方法。     

废旧锌锰电池制备Cu掺杂Mn-Zn铁氧体

以硝酸溶解废旧碱性锌锰电池所得的溶液为原料,以酒石酸为凝胶剂,采用sol-gel法制备出一系列Cu掺杂Mn-Zn铁氧体(Mn0.6–x/2Zn0.4–x/2CuxFe2O4,x=0.1,0.2,0.3和0.4)。经XRD、VSM测试,结果表明:Cu掺杂不仅没有改变Mn-Zn铁氧体的相结构,而且有利于尖晶石结构的形成;Cu掺杂后Mn-Zn铁氧体的Ms、Mr和Hc的变化趋势,都是先增大后减小,最适宜的掺杂量x为0.1。此时,Ms为2.66×105A/m,Mr为5.73×104A/m,Hc为1.6/π×104A/m。     

电梯导轨直线度和扭曲度检验系统的研制

为了解决电梯导轨直线度和扭曲度检验中需要的直线和角度基准问题,采用十字线激光束和图像处理技术开发了电梯导轨直线度和扭曲度检验系统.激光源固定在导轨的一端,移动光靶在导轨上移动并在指定位置摄取十字线激光束图像,图像经处理后获得十字线交叉点坐标和横线倾角.介绍了移动光靶的设计方法和交点坐标和扭曲角的计算方法,并对由扭曲产生的误差进行修正.用波长658 nm的激光器、640×480 pixel摄像机,光靶分辨率为0.055 66 mm/pixel,在5 m处摄取50 frame图像,标准偏差横向为0.022 3 mm、纵向为0.008 30 mm和角度为1.17′.实验结果表明,采用该方法的电梯导轨直线度和扭曲度检验系统,结构简单,操作方便,测量准确.     

Correlations between amino acid hydrophobicity scales and stain exclusion capacity of type 1 collagen fibrils

The relationship between the negative staining band pattern of type 1 native collagen fibrils and the amino acid distribution along the fibril axis was studied by comparing averaged microdensitograms with theoretical traces calculated on the basis of different amino acid parameters. As well as the spatial parameter "bulkiness" (volume/length, ratio), various literature-reported scales of "hydrophobicity" were tested. Two "hydrophobicity" sets allowed a better fit with the actual patterns than "bulkiness" values. However, a general improvement in simulations was achieved by associating most "hydrophobicity" sets with the "bulkiness" set. These results suggest that amino acid "hydrophobicity" plays a key role in the appearance of negative staining patterns but a composite mechanism would seem to occur: the accessibility of available intermolecular interstices may be conditioned by molecular hindrance, corresponding to amino acid "bulkiness" as well as by water-repulsion effect, which correlates with amino acid "hydrophobicity." Moreover, a detailed comparison of actual and simulated patterns suggests that a modulation exists in the effectiveness of these two factors along each D-period according to the different molecular packing and concentration of hydrophobic amino acid clusters within overlap regions and gap regions, respectively.     

Detecting Space-Time Alternating Biological Signals Close to the Bifurcation Point

Time-alternating biological signals, i.e., alternans, arise in variety of physiological states marked by dynamic instabilities, e.g., period doubling. Normally, a sequence of large–small–large transients, they can exhibit variable patterns over time and space, including spatial discordance. Capture of the early formation of such alternating regions is challenging because of the spatiotemporal similarities between noise and the small-amplitude alternating signals close to the bifurcation point. We present a new approach for automatic detection of alternating signals in large noisy spatiotemporal datasets by exploiting quantitative measures of alternans evolution, e.g., temporal persistence, and by preserving phase information. The technique specifically targets low amplitude, relatively short alternating sequences and is validated by combinatorics-derived probabilities and empirical datasets with white noise. Using high-resolution optical mapping in live cardiomyocyte networks, exhibiting calcium alternans, we reveal for the first time early fine-scale alternans, close to the noise level, which are linked to the later formation of larger regions and evolution of spatially discordant alternans. This robust method aims at quantification and better understanding of the onset of cardiac arrhythmias and can be applied to general analysis of space-time alternating signals, including the vicinity of the bifurcation point.      

Abnormal formation of the glucan network from regenerating protoplasts in Schizosaccharomyces pombe cps8 actin point mutant

To study the close relationship between the actin cytoskeleton and cell wall formation, the process of cell wall formation in reverting protoplasts of the fission yeast, Schizosaccharomyces pombe, cps8 actin point mutant was investigated by ultra-high-resolution low-voltage scanning electron microscopy (UHR-LVSEM) and transmission electron microscopy (TEM). The protoplast of the cps8 mutant began to form a glucan network in a unipolar manner and to secrete alpha-galactomannan. The site of cell wall formation grew in a cylindrical shape in the wild-type protoplast. The alpha-galactomannan did not fill in the intrafibrillar spaces completely, however, and the fibrils were exposed on the cell surface. UHR-LVSEM images indicated that the glucan fibrils were thin and rope-shaped, forming a looser network than the wild-type. TEM images indicated the finest fibrils were approximately 1.5 nm in diameter, the same diameter as the wild-type. These results suggest that the cps8 mutant was insufficient in developing cross-linkage with the glucan fibrils up to the wide ribbon shape as found in the wild-type [Osumi M et al. (1989) J. Electron Microsc. 38: 457-468; Osumi M (1998) Micron 29: 207-233]. These findings appear to indicate that the actin cytoskeleton controls formation of the glucan network and secretion of beta-1,6-glucan, and confirm the close relationship of the actin cytoskeleton and glucan formation.     

系统性淀粉样变性的超微病理诊断

目的:应用光镜(LM)及透射电镜(TEM)观察不同部位淀粉样物质的沉积及超微结构特点,为系统性淀粉样变性提供可靠的病理诊断依据.方法:对21例临床拟诊为系统性淀粉样变性病例的肾脏,腹壁脂肪和直肠粘膜活检组织按常规进行LM及TEM标本制备及病理检查.结果:LM观察显示淀粉样物质在肾脏,腹壁脂肪和直肠粘膜沉积阳性率分别为7...     

Liquid Crystal Enabled Early Stage Detection of Beta Amyloid Formation on Lipid Monolayers

Liquid crystals (LCs) can serve as sensitive reporters of interfacial events, and this property has been used for sensing of synthetic or biological toxins. Here it is demonstrated that LCs can distinguish distinct molecular motifs and exhibit a specific response to beta‐sheet structures. That property is used to detect the formation of highly toxic protofibrils involved in neurodegenerative diseases, where it is crucial to develop methods that probe the early‐stage aggregation of amyloidogenic peptides in the vicinity of biological membranes. In the proposed method, the amyloid fibrils formed at the lipid–decorated LC interface can change the orientation of LCs and form elongated and branched structures that are amplified by the mesogenic medium; however, nonamyloidogenic peptides form ellipsoidal domains of tilted LCs. Moreover, a theoretical and computational analysis is used to reveal the underlying structure of the LC, thereby providing a detailed molecular‐level view of the interactions and mechanisms responsible for such motifs. The corresponding signatures can be detected at nanomolar concentrations of peptide by polarized light microscopy and much earlier than the ones that can be identified by fluorescence‐based techniques. As such, it offers the potential for early diagnoses of neurodegenerative diseases and for facile testing of inhibitors of amyloid formation.     

An efficient interference mitigation approach via quasi‐access in two‐tier macro‐femto heterogeneous networks

Two‐tier heterogeneous networks, where the current cellular networks, that is, macrocells, are overlapped with a large number of randomly distributed femtocells, can potentially bring significant benefits to spectral utilization and system capacity. In a two‐tier network, the cross‐tier interference needs to be handled properly. Unlike the downlink interference, the uplink (UL) interference at femtocell caused by macrocell user equipment (MUE) has not been addressed sufficiently. When an MUE is located near the coverage of femtocell, its transmit power may cause UL interference to the femtocell receiver, especially for the closed subscriber group femtocells that share the entire frequency spectrum with macrocell. We propose a novel quasi‐access strategy, which allows the interfering MUE to connect with the interfered femtocell access point (FAP) while only via UL. It can significantly alleviate the UL interference at the FAP as well as its neighbors, in the meantime, benefit the macro‐tier. Copyright © 2013 John Wiley & Sons, Ltd.     

Peptide Materials Obtained by Aggregation of Polyphenylalanine Conjugates as Gadolinium‐Based Magnetic Resonance Imaging Contrast Agents

Peptide materials based on the aggregation of polyphenylalanine conjugates containing gadolinium complexes and acting as potential contrast agents (CAs) in magnetic resonance imaging (MRI) are described. Monomers contain two (F2) or four (F4) phenylalanine residues for self‐assembly, a chelating agent, 1,4,7,10‐tetraazacyclododecane‐N,N,N,N‐tetraacetic acid (DOTA) or diethylenetriaminepentaacetic acid (DTPA), for achieving gadolinium coordination, and ethoxylic linkers at two (L₂) or six (L₆) poly(ethylene glycol) (PEG) units between the chelating group and the peptide region. Both DOTA and DTPA tetraphenylalanine derivatives, and their gadolinium complexes DOTA(Gd)‐L₆‐F4 and DTPA(Gd)‐L₆‐F4, are able to self‐aggregate at very low concentration. Structural characterization, obtained by circular dichroism and infrared measurements, confirms the amyloid type fibril formation in which an antiparallel peptide alignment is preferred. Amyloid type fibril formation is also observed, in solid state, by transmission electron microscopy images and X‐ray diffraction patterns. The relaxivity values of DOTA(Gd)‐L₆‐F4 and DTPA(Gd)‐L₆‐F4 and their ability to enhance the MRI cellular response on the J774A.1 mouse macrophages cell line indicate that these peptide materials are promising candidate as a new class of supramolecular gadolinium based MRI contrast agents.     

硅基液晶（LCOS）与反射显示模式的关态特性

文章概述了硅基液晶（LCOS）所使用的反射式显示模式的关态特性,研究基础是均匀扭曲液晶盒的Jones矩阵,同时介绍了郭海成提出的参数空间方法和基于光学等价定理的“理想”模式,并强调了显示模式本身引起的光学色散,而光的利用率要求备选模式落在参数空间曲线的极值点附近。     

Hybrid Proton and Electron Transport in Peptide Fibrils

Protons and electrons are being exploited in different natural charge transfer processes. Both types of charge carriers could be, therefore, responsible for charge transport in biomimetic self‐assembled peptide nanostructures. The relative contribution of each type of charge carrier is studied in the present work for fibrils self‐assembled from amyloid‐β derived peptide molecules, in which two non‐natural thiophene‐based amino acids are included. It is shown that under low humidity conditions both electrons and protons contribute to the conduction, with current ratio of 1:2 respectively, while at higher relative humidity proton transport dominates the conductance. This hybrid conduction behavior leads to a bimodal exponential dependence of the conductance on the relative humidity. Furthermore, in both cases the conductance is shown to be affected by the peptide folding state under the entire relative humidity range. This unique hybrid conductivity behavior makes self‐assembled peptide nanostructures powerful building blocks for the construction of electric devices that could use either or both types of charge carriers for their function.