Elasticity of crystalline beta-sheet monolayers

Designed amphiphilic beta-sheet peptides with the sequence Pro-Glu-(Phe-Glu)(n)-Pro (n = 2-7) were previously shown by grazing incidence X-ray diffraction (GIXD), to form ordered two-dimensional (2-D) monolayer structures at interfaces induced by the proline residues at peptide termini. The GIXD diffraction pattern was modeled with two coexisting lattice arrangements, suggesting structural flexibility exhibited in the multiple ways by which beta-strands and their amino acid side chains pack into ordered 2-D structures. Here, we find by in-situ GIXD measurements that the ordered beta-sheet assemblies may undergo a quasi-reversible compression and expansion cycle at the air-water interface. The diffraction measurements indicate that on compression the repeat distance that corresponds to the long axes of the peptide strands may decrease by up to 37% in length. Upon expansion the compressed beta-sheet assemblies revert elastically to their original conformation. The interstrand repeat distance along the peptide hydrogen bonds apparently does not change along the film compression and expansion. Based on the GIXD data, at surface pressures higher than approximately 3 mN/m, beyond the peptide limiting area per molecule, the compressibility is 7.4 +/- 0.6 m/N. The out-of-plane Bragg rod diffraction patterns imply that in the compressed state the beta-strands buckle up in reaction to the increase in surface pressure. At low surface pressure, the 2-D compressibility of the crystalline beta-sheet was estimated at approximately 32 m/N attributed to interdomain rearrangements.     

Dynamics of Zn(II) binding as a key feature in the formation of amyloid fibrils by Aβ11-28

Supramolecular assembly of peptides and proteins into amyloid fibrils is of multifold interest, going from materials science to physiopathology. The binding of metal ions to amyloidogenic peptides is associated with several amyloid diseases, and amyloids with incorporated metal ions are of interest in nanotechnology. Understanding the mechanisms of amyloid formation and the role of metal ions can improve strategies toward the prevention of this process and enable potential applications in nanotechnology. Here, studies on Zn(II) binding to the amyloidogenic peptide Aβ11-28 are reported. Zn(II) modulates the Aβ11-28 aggregation, in terms of kinetics and fibril structures. Structural studies suggest that Aβ11-28 binds Zn(II) by amino acid residues Glu11 and His14 and that Zn(II) is rapidly exchanged between peptides. Structural and aggregation data indicate that Zn(II) binding induces the formation of the dimeric Zn(II)(1)(Aβ11-28)(2) species, which is the building block of fibrillar aggregates and explains why Zn(II) binding accelerates Aβ11-28 aggregation. Moreover, transient Zn(II) binding, even briefly, was enough to promote fibril formation, but the final structure resembled that of apo-Aβ11-28 amyloids. Also, seeding experiments, i.e., the addition of fibrillar Zn(II)(1)(Aβ11-28)(2) to the apo-Aβ11-28 peptide, induced aggregation but not propagation of the Zn(II)(1)(Aβ11-28)(2)-type fibrils. This can be explained by the dynamic Zn(II) binding between soluble and aggregated Aβ11-28. As a consequence, dynamic Zn(II) binding has a strong impact on the aggregation behavior of the Aβ11-28 peptide and might be a relevant and so far little regarded parameter in other systems of metal ions and amyloidogenic peptides.     

Triggers for β-sheet formation at the hydrophobic-hydrophilic interface: high concentration, in-plane orientational order, and metal ion complexation

Amyloid formation plays a causative role in neurodegenerative diseases such as Alzheimer's disease or Parkinson's disease. Soluble peptides form β-sheets that subsequently rearrange into fibrils and deposit as amyloid plaques. Many parameters trigger and influence the onset of the β-sheet formation. Early stages are recently discussed to be cell-toxic. Aiming at understanding various triggers such as interactions with hydrophobic-hydrophilic interfaces and metal ion complexation and their interplay, we investigated a set of model peptides at the air-water interface. We are using a general approach to a variety of diseases such as Alzheimer's disease, Parkinson's disease, and type II diabetes that are connected to amyloid formation. Surface sensitive techniques combined with film balance measurements have been used to assess the conformation of the peptides and their orientation at the air-water interface (IR reflection-absorption spectroscopy). Additionally, the structures of the peptide layers were characterized by grazing incidence X-ray diffraction and X-ray reflectivity. The peptides adsorb to the air-water interface and immediately adopt an α-helical conformation. This helical intermediate transforms into β-sheets upon further triggering. The factors that result in β-sheet formation are dependent on the peptide sequence. In general, the interface has the strongest effect on peptide conformation compared to high concentrations or metal ions. Metal ions are able to prevent aggregation in bulk but not at the interface. At the interface, metal ion complexation has only minor effects on the peptide secondary structure, influencing the in-plane structure that is formed in two dimensions. At the air-water interface, increased concentrations or a parallel arrangement of the α-helical intermediates are the most effective triggers. This study reveals the role of various triggers for β-sheet formation and their complex interplay. Our main finding is that the hydrophobic-hydrophilic interface largely governs the conformation of peptides. Therefore, the present study implies that special care is needed when interpreting data that may be affected by different amounts or types of interfaces during experimentation.     

Macrocyclic β-sheet peptides that inhibit the aggregation of a tau-protein-derived hexapeptide

This paper describes studies of a series of macrocyclic β-sheet peptides 1 that inhibit the aggregation of a tau-protein-derived peptide. The macrocyclic β-sheet peptides comprise a pentapeptide "upper" strand, two δ-linked ornithine turn units, and a "lower" strand comprising two additional residues and the β-sheet peptidomimetic template "Hao". The tau-derived peptide Ac-VQIVYK-NH(2) (AcPHF6) aggregates in solution through β-sheet interactions to form straight and twisted filaments similar to those formed by tau protein in Alzheimer's neurofibrillary tangles. Macrocycles 1 containing the pentapeptide VQIVY in the "upper" strand delay and suppress the onset of aggregation of the AcPHF6 peptide. Inhibition is particularly pronounced in macrocycles 1a, 1d, and 1f, in which the two residues in the "lower" strand provide a pattern of hydrophobicity and hydrophilicity that matches that of the pentapeptide "upper" strand. Inhibition varies strongly with the concentration of these macrocycles, suggesting that it is cooperative. Macrocycle 1b containing the pentapeptide QIVYK shows little inhibition, suggesting the possibility of a preferred direction of growth of AcPHF6 β-sheets. On the basis of these studies, a model is proposed in which the AcPHF6 amyloid grows as a layered pair of β-sheets and in which growth is blocked by a pair of macrocycles that cap the growing paired hydrogen-bonding edges. This model provides a provocative and appealing target for future inhibitor design.     

Infrared reflection-absorption spectroscopy and polarization-modulated infrared reflection-absorption spectroscopy studies of the aequorin langmuir monolayer

The Langmuir monolayer of aequorin and apoaequorin was studied by infrared reflection-absorption spectroscopy (IRRAS) and polarization-modulated IRRAS techniques. The alpha-helices in the aequorin Langmuir monolayer were parallel to the air-water interface at zero surface pressure. When the surface pressure increased to 15 mN.(m-1), the alpha-helices became tilted and the turns became parallel to the air-water interface. As for apoaequorin, the alpha-helices were also parallel to the air-water interface at 0 mN.m(-1). However, the alpha-helix became tilted and the turns became parallel to the air-water interface quickly at 5 mN.m(-1). With further compression of the apoaequorin Langmuir monolayer, the orientation remained the same. The different behaviors of aequorin and apoaequorin at the air-water interface were explained by the fact that aequorin formed dimers at the air-water interface but apoaequorin was a monomer. It is more difficult for a dimer to be tilted by the compression of the Langmuir monolayer.     

Protofilaments, filaments, ribbons, and fibrils from peptidomimetic self-assembly: implications for amyloid fibril formation and materials science

Deciphering the mechanism(s) of β-sheet mediated self-assembly is essential for understanding amyloid fibril formation and for the fabrication of polypeptide materials. Herein, we report a simple peptidomimetic that self-assembles into polymorphic β-sheet quaternary structures including protofilaments, filaments, fibrils, and ribbons that are reminiscent of the highly ordered structures displayed by the amyloidogenic peptides Aβ, calcitonin, and amylin. The distribution of quaternary structures can be controlled by and in some cases specified by manipulating the pH, buffer composition, and the ionic strength. The ability to control β-sheet-mediated assembly takes advantage of quaternary structure dependent pK(a) perturbations. Biophysical methods including analytical ultracentrifugation studies as well as far-UV circular dichroism and FT-IR spectroscopy demonstrate that linked secondary and quaternary structural changes mediate peptidomimetic self-assembly. Electron and atomic force microscopy reveal that peptidomimetic assembly involves numerous quaternary structural intermediates that appear to self-assemble in a convergent fashion affording quaternary structures of increasing complexity. The ability to control the assembly pathway(s) and the final quaternary structure(s) afforded should prove to be particularly useful in deciphering the quaternary structural requirements for amyloid fibril formation and for the construction of noncovalent macromolecular structures.     

Emulsifying properties of acylated rapeseed (Brassica napus L.) peptides

A peptide fraction having an average size of 5.6 amino acids has been purified from a rapeseed hydrolyzate, acylated using C(10)-C(14) acyl chlorides, and the surface tension values at the air-water interface and emulsifying properties studied. As compared with standard surface-active proteins, such as bovine serum albumin (BSA), and with detergents such as sodium dodecyl sulfate (SDS), acylated peptides exhibited particular surface characteristics. The surface tension at air-water interface of acylated peptides ranged from 29.1 to 37.8 mN/m at equilibrium; these values were considerably lower than those for BSA and closer those for SDS, suggesting that acylated peptides pack at the air-water interface more like detergents than like proteins. The adsorption of acylated peptides to the oil-water interface was slower than for SDS or BSA, as deduced from the rather large size of oil droplets in emulsions (31-17 microm). Consequently, these emulsions creamed extensively during aging. Nevertheless, emulsions generated from acylated peptides were in general more stable to phase separation than those prepared from SDS. The C(14) acylated peptides were more effective for generating emulsions than the C(10) and C(12) derivatives, especially concerning the stability of emulsions against coalescence and phase separation, which was better than SDS and close to BSA.     

Structure and orientation changes of omega- and gamma-gliadins at the air-water interface: a PM-IRRAS spectroscopy and Brewster angle microscopy study

Microscopic and molecular structures of omega- and gamma-gliadin monolayers at the air-water interface were studied under compression by three complementary techniques: compression isotherms, polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), and Brewster angle microscopy (BAM). For high molecular areas, gliadin films are homogeneous, and a flat orientation of secondary structures relative to the interface is observed. With increasing compression, the nature and orientation of secondary structures changed to minimize the interfacial area. The gamma-gliadin film is the most stable at the air-water interface; its interfacial volume is constant with increasing compression, contrary to omega-gliadin films whose molecules are forced out of the interface. gamma-Gliadin stability at a high level of compression is interpreted by a stacking model.     

Natural Compounds against Alzheimer’s Disease: Molecular Recognition of Aβ1–42 Peptide by Salvia sclareoides Extract and its Major Component,Rosmarinic Acid,as Investigated by NMR

Amyloid peptides, Aβ1–40 and Aβ1–42, represent major molecular targets to develop potential drugs and diagnostic tools for Alzheimer’s Disease (AD). In fact, oligomeric and fibrillar aggregates generated by these peptides are amongst the principal components of amyloid plaques found post mortem in patients suffering from AD. Rosmarinic acid has been demonstrated to be effective in preventing the aggregation of amyloid peptides in vitro and to delay the progression of the disease in animal models. Nevertheless, no information is available about its molecular mechanism of action. Herein, we report the NMR characterization of the interaction of Salvia sclareoides extract and that of its major component, rosmarinic acid, with Aβ1–42 peptide, whose oligomers have been described as the most toxic Aβ species in vivo. Our data shed light on the structural determinants of rosmarinic acid–Aβ1–42 oligomers interaction, thus allowing the elucidation of its mechanism of action. They also provide important information for the rational design of new compounds with higher affinity for Aβ peptides to generate new anti‐amyloidogenic molecules and/or molecular tools for the specific targeting of amyloid aggregates in vivo. In addition, we identified methyl caffeate, another natural compound present in different plants and human diet, as a good ligand of Aβ1–42 oligomers, which also shows anti‐amyloidogenic activity. Finally, we demonstrated the possibility to exploit STD‐NMR and trNOESY experiments to screen extracts from natural sources for the presence of Aβ peptide ligands.     

Multiscale surface self-assembly of an amyloid-like peptide

We present the 2D self-assembly properties of an amyloid-like peptide (LSFDNSGAITIG-NH2) (i.e., LSFD) over a whole range of spatial scales. This peptide is known to adopt an amyloid-like behavior in water where it aggregates into fibrils. Monolayers of this 12 amino acid peptide were built by direct spreading and compression of an organic unstructured LSFD solution at the air/water interface. Investigation by infrared spectroscopy of the peptide secondary structure reveals beta-sheet formation at the water surface. As evidenced by Brewster angle microscopy, compression of the peptidic film results in the formation of large condensed domains. We used atomic force microscopy to show that these domains are made of rather monodisperse, elongated domains of monomolecular thickness, which are about 1 microm long and hundred of nanometers wide. These nanodomains can be compacted up to the formation of a homogeneous monolayer on the micrometer scale. These bidimensional structures appear as a surface-induced counterpart of the bulk amyloid fibrils that do not form at the air/water interface. These self-assembled peptide nanostructures are also very promising for building organized nanomaterials.     

Adsorption of amyloid beta (1-40) peptide to phosphatidylethanolamine monolayers.

The aggregation of soluble, nontoxic amyloid beta (Abeta) peptide to beta-sheet containing fibrils is assumed to be a major step in the development of Alzheimer's disease. Interactions of Abeta with neuronal membranes could play a key role in the pathogenesis of the disease. Herein, we study the adsorption of synthetic Abeta peptide to DPPE and DMPE monolayers (dipalmitoyl- and dimyristoylphosphatidylethanolamine). Both lipids exhibit a condensed monolayer state at 20 degrees C and form a similar lattice. However, at low packing densities (at large area per molecule), the length of the acyl chains determines the phase behavior, therefore DPPE is fully condensed whereas DMPE exhibits a liquid-expanded state with a phase transition at approximately 5-6 mNm(-1). Adsorption of Abeta to DPPE and DMPE monolayers at low surface pressure leads to an increase of the surface pressure to approximately 17 mNm(-1). The same was observed during adsorption of the peptide to a pure air-water interface. Grazing incidence X-ray diffraction (GIXD) experiments show no influence of Abeta on the lipid structure. The adsorption kinetics of Abeta to a DMPE monolayer followed by IRRAS (infrared reflection absorption spectroscopy) reveals the phase transition of DMPE molecules from liquid-expanded to condensed states at the same surface pressure as for DMPE on pure water. These facts indicate no specific interactions of the peptide with either lipid. In addition, no adsorption or penetration of the peptide into the lipid monolayers was observed at surface pressures above 30 mNm(-1). IRRAS allows the measurement of the conformation and orientation of the peptide adsorbed to the air-water interface and to a lipid monolayer. In both cases, with lipids at surface pressures below 20 mNm(-1) and at the air-water interface, adsorbed Abeta has a beta-sheet conformation and these beta-sheets are oriented parallel to the interface.     

Fibril Structure Demonstrates the Role of Iodine Labelling on a Pentapeptide Self-Assembly

Iodination has long been employed as a successful labelling strategy to gain structural insights into proteins and other biomolecules via several techniques, including Small Angle X-ray Scattering, Inductively Coupled Plasma Mass Spectrometer (ICP-MS), and single-crystal crystallography. However, when dealing with smaller biomolecular systems, interactions driven by iodine may significantly alter their self-assembly behaviour. The engineering of amyloidogenic peptides for the development of ordered nanomaterials has greatly benefitted from this possibility. Still, to date, iodination has exclusively been applied to aromatic residues. In this work, an aliphatic bis-iodinated amino acid was synthesized and included into a custom pentapeptide, which showed enhanced fibrillogenic behaviour. Peptide single crystal X-ray structure and powder X-ray diffraction on its dried water solution demonstrated the key role of iodine atoms in promoting intermolecular interactions that drive the peptide self-assembly into amyloid fibrils. These findings enlarge the library of halogenated moieties available for directing and engineering the self-assembly of amyloidogenic peptides.     

Near-Wall Aggregation of Amyloidogenic Aβ 1-40 Peptide: Direct Observation by the FRET

The formation of amyloid fibrils is one of the variants of the self-organization of polypeptide chains. For the amyloid aggregation, the solution must be oversaturated with proteins. The interface of the liquid (solution) and solid (vessel walls) phases can trigger the adsorption of protein molecules, and the resulting oversaturation can initiate conformational transitions in them. In any laboratory experiment, we cannot exclude the presence of surfaces such as the walls of vessels, cuvettes, etc. However, in many works devoted to the study of amyloid formation, this feature is not considered. In our work, we investigated the behavior of the Aβ 1-40 peptide at the water–glass, water–quartz, and water–plastic interface. We carried out a series of simple experiments and showed that the Aβ 1-40 peptide is actively adsorbed on these surfaces, which leads to a significant interaction and aggregation of peptides. This means that the interface can be the place where the first amyloid nucleus appears. We suggest that this effect may also be one of the reasons for the difficulty of reproducing kinetic data when studying the aggregation of the amyloid of the Aβ 1-40 peptide and other amyloidogenic proteins     

Rat osseous plate alkaline phosphatase as Langmuir monolayer--an infrared study at the air-water interface

A glycosylphosphatidylinositol (GPI)-anchored enzyme (rat osseous plate alkaline phosphatase-OAP) was studied as monolayer (pure and mixed with lipids) at the air-water interface. Surface pressure and surface potential-area isotherms showed that the enzyme forms a stable monolayer and exhibits a liquid-expanded state even at surface pressure as high as 30 mN m(-1). Isotherms for mixed dimyristoylphosphatidic acid (DMPA)-OAP monolayer showed the absence of a liquid-expanded/liquid-condensed phase transition as observed for pure DMPA monolayer. In both cases, pure or mixed monolayer, the enzyme preserves its native conformation under compression at the air-water interface as observed from in situ p-polarized light Fourier transform-infrared reflection-absorption spectroscopic (FT-IRRAS) measurements. Changes in orientation and conformation of the enzyme due to the presence or absence of DMPA, as well as due to the surface compression, are discussed.     

Structural Insight into IAPP-Derived Amyloid Inhibitors and Their Mechanism of Action

Designed peptides derived from the islet amyloid polypeptide (IAPP) cross-amyloid interaction surface with Aβ (termed interaction surface mimics or ISMs) have been shown to be highly potent inhibitors of Aβ amyloid self-assembly. However, the molecular mechanism of their function is not well understood. Using solution-state and solid-state NMR spectroscopy in combination with ensemble-averaged dynamics simulations and other biophysical methods including TEM, fluorescence spectroscopy and microscopy, and DLS, we characterize ISM structural preferences and interactions. We find that the ISM peptide R3-GI is highly dynamic, can adopt a β-like structure, and oligomerizes into colloid-like assemblies in a process that is reminiscent of liquid–liquid phase separation (LLPS). Our results suggest that such assemblies yield multivalent surfaces for interactions with Aβ40. Sequestration of substrates into these colloid-like structures provides a mechanistic basis for ISM function and the design of novel potent anti-amyloid molecules.     

Structure inducing ionic liquids-enhancement of alpha helicity in the Abeta(1-40) peptide from Alzheimer's disease

We have studied the impact of ionic liquid solvents on the structure of the Abeta(1-40) peptide from Alzheimer's disease and found that ionic liquid solvents were able to induce a conformational change in the structure of the Abeta(1-40) peptide. This conformational change impacts the self-assembly of the peptide into amyloid fibrils.     

Self-assembly of polystyrene-block-poly(ethylene oxide) copolymers at the air-water interface: is dewetting the genesis of surface aggregate formation?

Block copolymer self-assembly at the air-water interface is commonly regarded as a two-dimensional counterpart of equilibrium block copolymer self-assembly in solution and in the bulk; however, the present analysis of atomic force microscopy (AFM) and isotherm data at different spreading concentrations suggests a nonequilibrium mechanism for the formation of various polystyrene-b-poly(ethylene oxide) (PS-b-PEO) aggregates (spaghetti, dots, rings, and chainlike aggregates) at the air-water interface starting with an initial dewetting of the copolymer spreading solution from the water surface. We show that different spreading concentrations provide kinetic snapshots of various stages of self-assembly at the air-water interface as a result of different degrees of PS chain entanglements in the spreading solution. Two block copolymers are investigated: MW = 141k (11.4 wt % PEO) and MW = 185k (18.9 wt % PEO). Langmuir compression isotherms for the 185k sample deposited from a range of spreading concentrations (0.1-2.0 mg/mL) indicate less dense packing of copolymer chains within aggregate cores formed at lower spreading concentrations due to a competition between the interfacial adsorption of PEO blocks and the kinetic restrictions of PS chain entanglements. From AFM analysis of the transferred Langmuir-Blodgett films, it is clear that PS chain entanglements in the spreading solution also affect the morphological evolution of surface aggregates for both samples, with earlier structures being trapped at higher concentrations. At the highest spreading concentration for the 141k copolymer, the coexistence of long spaghetti aggregates with cellular arrays of holes, along with various transition structures, indicates that various surface aggregates evolve from networks of rims formed as a result of dewetting of the evaporating spreading solution from the water surface.     

Synthesis and characterization of amphiphilic fullerenes and their Langmuir-Blodgett films

We report here the synthesis and characterization of three amphiphilic fullerene derivatives and their Langmuir-Blodgett thin films. Two of the C(60) amphiphiles are mono-derivatives with a long alkyl chain terminated with either -COOH (2) or NH(2) (3) as the hydrophilic headgroup, and the third one (5) is designed to bear the same NH(2) group as 3 but with 10 additional hydrophobic alkyl chains grafted on the C(60) sphere (Scheme 1). These amphiphiles form stable, ordered monolayers at the air-water interface. The molecular packing at the air-water interface and the mean area per molecule are determined by pressure isotherms at room temperature. Hysteresis of pressure isotherms of side chain C(60) (5) shows complete reversibility upon compression and decompression, which suggests that side chains on the C(60) sphere inhibit formation of aggregates at the air-water interface. Comparative studies of all three amphiphiles allow us to better determine the interaction between C(60)'s and their self-assembly kinetics at the air-water interface. Monolayers of monoderivatized amphiphiles (2 and 3) were transferred successfully onto quartz substrates as Z-type multilayered Langmuir-Blodgett films, and monolayers of 5 were transferred as Y-type films. Detailed characterization of the multilayer films (Z-type deposition) prepared from amine-terminated C(60) (3) using X-ray and neutron reflectometry reveals staggering of C(60) spheres and a head-to-head (Y-type) structure presumably due to flipping and reattaching of C(60) amphiphiles to the previous underlying C(60) layer.     

Sheet-like assemblies of charged amphiphilic α/β-peptides at the air-water interface

There is growing interest in the design of molecules that undergo predictable self-assembly. Bioinspired oligomers with well-defined conformational propensities are attractive from this perspective, since they can be constructed from diverse building blocks, and self-assembly can be directed by the identities and sequence of the subunits. Here we describe the structure of monolayers formed at the air-water interface by amphiphilic α/β-peptides with 1:1 alternation of α- and β-amino acid residues along the backbone. Two of the α/β-peptides, one a dianion and the other a dication, were used to determine differences between self-assemblies of the net negatively and positively charged oligomers. Two additional α/β-peptides, both zwitterionic, were designed to favor assembly in a 1:1 molar ratio mixture with parallel orientation of neighboring strands. Monolayers formed by these α/β-peptides at the air-water interface were characterized by surface pressure-area isotherms, grazing incidence X-ray diffraction (GIXD), atomic force microscopy and ATR-FTIR. GIXD data indicate that the α/β-peptide assemblies exhibited diffraction features similar to those of β-sheet-forming α-peptides. The diffraction data allowed the construction of a detailed model of an antiparallel α/β-peptide sheet with a unique pleated structure. One of the α/β-peptide assemblies displayed high stability, unparalleled among previously studied assemblies of α-peptides. ATR-FTIR data suggest that the 1:1 mixture of zwitterionic α/β-peptides assembled in a parallel arrangement resembling that of a typical parallel β-sheet secondary structure formed by α-peptides. This study establishes guidelines for design of amphiphilic α/β-peptides that assemble in a predictable manner at an air-water interface, with control of interstrand orientation through manipulation of Coulombic interactions along the backbone.     

Self-assembly of ionic liquids-stabilized Pt nanoparticles into two-dimensional patterned nanostructures at the air-water interface

In this paper, we demonstrate the self-assembly of ionic liquids (ILs)-stabilized Pt nanoparticles into two-dimensional (2D) patterned nanostructures at the air-water interface under ambient conditions. Here, ILs are not used as solvents but as mediators by virtue of their pronounced self-organization ability in synthesis of self-assembled, highly organized hybrid Pt nanostructures. It is also found that the morphologies of the 2D patterned nanostructures are directly connected with the quantities of ILs. Due to the special structures of ILs-stabilized Pt nanoparticles, 2D patterned Pt nanostructures can be formed through the pi-pi stack interactions and hydrogen bonds. The resulting 2D patterned Pt nanostructures exhibit good electrocatalytic activity toward oxygen reduction.