Assemblies of Metal Nanoparticles and Self‐Assembled Peptide Fibrils—Formation of Double Helical and Single‐Chain Arrays of Metal Nanoparticles

Abstract

[tBu 4 PcIn] 2 O are almost identical despite the difference in their saturation energy densities.In summary, spectroscopic data and excited relaxation data of the In-and Ga-Pcs employed in the present study do not show aggregation phenomena to reduce the effective nonlinear absorption. [8,13] The optical limiting in these compounds is very effective compared to other phthalocyanines [18] exhibiting a range of saturation densities and absorption cross-section ratios. Axial substitution of the p-TMP functional group at the central gallium and indium in 1 and 3 results in a reduction of the saturation energy density by a factor in excess of 3. This method of tailoring the saturation of the optical limiters will prove to be very useful in the construction of passive organic optical limiters where multiple layers of effective absorbers with decreasing saturation may be desirable. ExperimentalThe synthesis and structural characterization of compounds 1±5 have been previously reported [9,11,12]. All solvents used were purified, dried and distilled under dry nitrogen. UV-vis spectra were recorded in Shimadzu UV-365. Fluorescence spectra and lifetimes were measured by a single-photon counting method using an argon ion laser, a pumped Ti:sapphire laser (Spectra-Physics, Tsunami 3960, FWHM 150 fs) with a pulse selector (Spectra-Physics, 3980), a second harmonic generator (Spectra-Physics, GWU-23PS), and a streakscope (Hamamatsu Photonics, C4334-01). Each sample was excited in toluene with 410 nm laser light.The open aperture of a Z-scan experiment [16] was used to measure the optical limiting response in the samples. All experiments described in this study were performed using 6 ns 532 nm laser light pulses from a Q switched frequency doubled Nd:YAG laser with a pulse repetition rate of 10 Hz. The beam was spatially filtered to remove the higher order modes and tightly focused using a 9 cm focal length lens. All samples were measured in quartz cells with a 1 mm optical path length, and at concentrations of 0.5 g L ±1 (~10 ±4 M) in toluene. There is growing interest in attempts to combine biomaterials and inorganic nanoparticles and investigating their properties. One of the research motivations for this combination is to take advantage of the well-defined structures and special properties of biomolecules and their supermolecular structures to organize the nanoparticles into predefined, topologically intricate nanostructures or to synthesize miscellaneous materials for potential applications in electronic, optical, and chemical devices.[1] Several kinds of biomaterials have been

Mechanism of amyloidogenesis: nucleation-dependent fibrillation versus double-concerted fibrillation

“…Diphenylalanine nanotubes were also demonstrated to be a suitable scaffold for platinum-peptide composites (32), silver nanowires (33), and coaxial metal nanocables (34). Au and Pd nanoparticles deposited on the fibrils of a 12 residue synthetic peptide (T1) resulted in the formation of double helical and single-chain arrays of metal nanoparticles (35). In addition, amyloid fibril structures have been utilized for protein and enzyme immobilization.…”

Toward Greener Nanosynthesis

“…A wide range of biologically derived substrates have proven useful, including RNA, [312][313][314] viruses, 277,278,[315][316][317][318][319][320] and proteins/ peptides. [321][322][323][324][325][326][327][328][329] Proper substrate selection affords an additional opportunity to control the morphology of the assembled array, as the final structure typically mimics that of the substrate; that is, planar substrates may support twodimensional arrays, whereas substrates having a relatively linear structure are best suited to one-dimensional structures. Advanced surface treatments including lithographic patterning [330][331][332][333][334] and patterning/stamping techniques [335][336][337][338][339][340] can be used to generate patterned arrays with specifically constrained dimensions, thus improving the versatility of planar substrates, although some techniques (electron and ion beam lithography) lack the efficient, parallel processing methods offered by simple self-assembly on molecular scaffolds.…”

Polarization at metal–biomolecular interfaces in solution

“…Peptides with high affinity to Au and Pd surfaces have been identified by phage display techniques [2,3,5,6,8,10] and specific non-covalent binding can be explained by complementarity of the molecular structure of the peptide to epitaxial face-centred cubic (FCC) lattice sites on the metal surface [12]. Accordingly, the binding strength of the peptide correlates with the surface energy of the metal and with competitive epitaxial binding preferences of sp 2 and sp 3 hybridized groups in comparison to solvent molecules on a given metal surface [12][13][14]. This concept of molecular epitaxy also explains the influence of curvature and roughness of metal nanoparticles on differential peptide adsorption [15].…”