Self-Assembled Nanostructures

2008 ◽  
Author(s):  
Wei Lu
Keyword(s):  
Self Assembly ◽  
Strain Field ◽  
The Self ◽  
Uniform Strain ◽  
Assembly Process ◽  
Elastic Substrate ◽  
Substrate Strain ◽  
Self Assembled

A binary monolayer on an elastic substrate may self-organize into ordered nanoscale phase patterns. Here we report a work of using a substrate strain field to guide the self-assembly process. The study shows that straining a substrate uniformly does not influence the pattern. However, a non-uniform strain field significantly influences the size, shape and distribution of self-assembled features. The study suggests a method of strain field design to make various monolayer patterns.

Engineering Monolayers With Strain Field

Materials ◽  
2004 ◽  
Author(s):  
Dongchoul Kim ◽  
Wei Lu
Keyword(s):  
Self Assembly ◽  
Strain Field ◽  
The Self ◽  
Uniform Strain ◽  
Assembly Process ◽  
Elastic Substrate ◽  
Substrate Strain ◽  
Nanoscale Patterns ◽  
Self Assembled

A binary monolayer on an elastic substrate may self-organize into ordered nanoscale patterns. Here we report a work of using a substrate strain field to guide the self-assembly process. The study shows that straining a substrate uniformly does not influence the pattern. However, a non-uniform strain field significantly influences the size, shape and distribution of self-assembled features. The study suggests a method of strain field design to make various monolayer patterns.

scholarly journals Self-assembled peptide nanostructures for electrical, optical, and magnetic applications

2018 ◽  
Author(s):  
◽  
Soma Khanra
Keyword(s):  
Electron Microscopy ◽  
Self Assembly ◽  
Nonlinear Optical ◽  
Electronic Devices ◽  
Longitudinal Component ◽  
The Self ◽  
Assembly Process ◽  
Experimental Characterization ◽  
X Ray ◽  
Self Assembled

Bio-nanotechnology has become a widespread exciting field of research as the basic biological structure of bio-inspired materials and nanotechnology share the common length scale. Bio-nanotechnology, which is mainly based on bio-inspired nanostructured materials, has potential applications in nanomedicine, drug delivery, bio-sensors, and bio-degradable electronic devices. The nanostructures obtained from biomolecules are attractive due to their biocompatibility for molecular recognition, ease of chemical modification, and the ability to scaffold other organic and inorganic materials. Peptide nanostructures formed through the self-assembly process of the basic building block of diphenylalanine show promising applications in biodegradable electronic devices, drug delivery, catalysis agent, waveguide, and frequency converter. This research focusses on the self-assembly process in a dipeptide, L, L diphenylalanine (FF) and exploring its electronic, optical, and magnetic properties. The role of solvents in the self-assembly process of FF is explored by combining density functional theory (DFT) along with experimental characterization techniques such as electron microscopy, Raman scattering, and x-ray diffraction (XRD). One of the objectives of this work was to explore the nonlinear optical (NLO) properties of FF nanostructures via second harmonic generation (SHG). The ratio of the nonlinear optical coefficients was obtained from individual FF nanotubes as a function of the tube diameter and thermal annealing conditions. The ratio of the shear to the longitudinal component (d15/d33) of the NLO coefficient increases with the diameter of the tubes. One of the transverse components, d31, of the NLO coefficient is found to be negative, and its magnitude with respect to the longitudinal component (d33) increases with the tube diameter. Thermal treatment of individual FF tubes has a similar effect as increasing the diameter of the tubes in SHG polarimetry. The functionalization of FF micro-nanostructures (FF-MNS) with nanomaterials was studied. FF-MNS with Ag or Au nanoparticles were explored in surface-enhanced Raman scattering (SERS). Such self-assembled nanostructures provide a natural template for tethering Au and Ag nanoparticles (Nps) due to its fractal surface. The FF-MNS undergo an irreversible phase transition from hexagonal packing (hex) to an orthorhombic (ort) structure at [about] 150 [degree]C. The metal Nps form chains on hex FF-MNS as inferred from transmission electron microscopy images and a uniform non-aggregated distribution in the ort phase. The SERS spectra obtained from R6G bound to FF-MNSs with AuNps show a higher enhancement for the ort phase compared with the hex phase. The experimental results agree well with our calculated Raman spectra of model systems using DFT. Our results indicate that FF-MNS both in the hex and ort phase can be used as substrates for SERS analysis with different metal Nps, opening up a novel class of optically active bio-based substrates. The use of magnetic nanoparticles with biomolecules offers a versatile path for tuning the functionality of the composite material for several applications. The functionalization of FF-MNS with cobalt ferrite (CFO) magnetic nanoparticles was achieved. The interaction between CFO nanoparticles and FF-MNS was investigated by optical spectroscopy, x-ray photoelectron spectroscopy (XPS), and magnetization measurements. The changes in the XPS data from pristine FF-MNS and CFO:FF-MNS are indicative of a charge transfer process from CFO to FF-MNS, changing the electronic states of the Fe2+ and Co2+ ions. A comparison of the magnetic characterization from CFO nanoparticles and CFO:FF-MNS shows a higher saturation magnetization from the nanocomposite sample, which is attributed to a change in the cationic distribution in CFO upon binding with the peptide. We were further successful in demonstrating the application of FF-MNS as a bio-degradable active layer in an organic light emitting diode (OLED). FF-MNS were functionalized with two blue-emitting conducting polymers: di-octyl-substituted polyfluorene (PF8) and ethyl-hexyl polyfluorene (PF2/6), and used as an active layer in an OLED architecture. A combination of molecular dynamics and experimental characterization techniques reveals a stronger binding mechanism for PF8 compared to PF2/6 with FF-MNS. Biodegradability tests from FF-MNS:PF8 nanocomposite films show more than 80% weight loss in 2 h by enzymatic action compared to PF8 pristine films, which do not degrade. Self-assembled FF-MNS with organic semiconductors open up a new generation of biocompatible and biodegradable materials in organic electronics.

scholarly journals STM visualisation of counterions and the effect of charges on self-assembled monolayers of macrocycles

2011 ◽  
Vol 2 ◽  
pp. 674-680 ◽  
Author(s):  
Tibor Kudernac ◽  
Natalia Shabelina ◽  
Wael Mamdouh ◽  
Sigurd Höger ◽  
Steven De Feyter
Keyword(s):  
Self Assembly ◽  
The Self ◽  
Self Assembled Monolayers ◽  
Assembly Process ◽  
Organic Monolayers ◽  
Preferential Adsorption ◽  
Scanning Tunnelling ◽  
Assembled Monolayers ◽  
Tunnelling Microscopy ◽  
Self Assembled

Despite their importance in self-assembly processes, the influence of charged counterions on the geometry of self-assembled organic monolayers and their direct localisation within the monolayers has been given little attention. Recently, various examples of self-assembled monolayers composed of charged molecules on surfaces have been reported, but no effort has been made to prove the presence of counterions within the monolayer. Here we show that visualisation and exact localisation of counterions within self-assembled monolayers can be achieved with scanning tunnelling microscopy (STM). The presence of charges on the studied shape-persistent macrocycles is shown to have a profound effect on the self-assembly process at the liquid–solid interface. Furthermore, preferential adsorption was observed for the uncharged analogue of the macrocycle on a surface.

scholarly journals Deciphering Molecular Self-Assembly through Electron Microscopy and Fluorescence Correlation Spectroscopy

2020 ◽  
Author(s):  
Subhankar Kundu ◽  
Arkaprava Chowdhury, ◽  
Somen Nandi ◽  
Kankan Bhattacharyya ◽  
Abhijit Patra
Keyword(s):  
Electron Microscopy ◽  
Self Assembly ◽  
Fluorescence Correlation Spectroscopy ◽  
Correlation Spectroscopy ◽  
The Self ◽  
Fine Tuning ◽  
Assembly Process ◽  
Molecular Aggregates ◽  
Fluorescence Correlation ◽  
Self Assembled

Supramolecular self-assembly of small organic molecules has emerged as a powerful tool to construct well-defined micro- and nanoarchitecture through fine-tuning a range of intermolecular interactions. The size, shape, and optical properties of these nanostructures largely depend on the temperature and polarity of the medium, along with the specific self-assembled pattern of molecular building units. The engineering of supramolecular self-assembled nanostructures with morphology-dependent tunable emission is in high demand due to the promising scope in nanodevices and molecular machines. However, challenges are probing the evolution of molecular aggregates from a true solution and directing the self-assembly process in a pre-defined fashion. The structure of molecular aggregates in the solution can be predicted from fluorescence correlation spectroscopy (FCS) and dynamic light scattering (DLS) analysis. On the other hand, the morphology of the aggregates can also be visualized through electron microscopy. Nevertheless, a direct correlation between emission from molecular aggregates in the aqueous dispersion and their morphology obtained through a solid-state characterization is missing. In the present study, we decipher the sequential evolution of molecular nanofibers from solution to spherical and oblong-shaped nanoparticles through the variation of solvent polarity, adjusting the <a>hydrophobic-hydrophilic interactions</a>. The intriguing case of molecular self-assembly is elucidated employing a newly designed π-conjugated thiophene derivative (TPAn) through a combination of steady-state absorption, emission measurements, FCS, and electron microscopy. The FCS analysis and microscopy results infer that small-sized nanofibers in the dispersion are further agglomerated, resulting in a network of nanofibers upon solvent evaporation. <a>The evolution of organic nanofibers and subtle control over the self-assembly process demonstrated in the current investigation provides a general paradigm to correlate the size, shape, and emission properties of diverse fluorescent molecular aggregates in complex heterogeneous media, including a human cell. </a>

Self-assembly and boosted photodegradation properties of perylene diimide via different solvents

2021 ◽  
Author(s):  
Ruizhe Yang ◽  
Jinyuan Liu ◽  
Bin Wang ◽  
Rong Wang ◽  
Yanhua Song ◽  
...  
Keyword(s):  
Photocatalytic Degradation ◽  
Self Assembly ◽  
The Self ◽  
Perylene Diimide ◽  
Assembly Process ◽  
Rapid Separation ◽  
Degradation Reaction ◽  
Self Assembled

Through different solvents, the self-assembly process of monomer PDI was studied. The rapid separation and transfer of the photogenerated carriers and π–π interaction between self-assembled PDI together boost the photocatalytic degradation reaction.

scholarly journals Deciphering Molecular Self-Assembly through Electron Microscopy and Fluorescence Correlation Spectroscopy

2020 ◽  
Author(s):  
Subhankar Kundu ◽  
Arkaprava Chowdhury, ◽  
Somen Nandi ◽  
Kankan Bhattacharyya ◽  
Abhijit Patra
Keyword(s):  
Electron Microscopy ◽  
Self Assembly ◽  
Fluorescence Correlation Spectroscopy ◽  
Correlation Spectroscopy ◽  
The Self ◽  
Fine Tuning ◽  
Assembly Process ◽  
Molecular Aggregates ◽  
Fluorescence Correlation ◽  
Self Assembled

Supramolecular self-assembly of small organic molecules has emerged as a powerful tool to construct well-defined micro- and nanoarchitecture through fine-tuning a range of intermolecular interactions. The size, shape, and optical properties of these nanostructures largely depend on the temperature and polarity of the medium, along with the specific self-assembled pattern of molecular building units. The engineering of supramolecular self-assembled nanostructures with morphology-dependent tunable emission is in high demand due to the promising scope in nanodevices and molecular machines. However, challenges are probing the evolution of molecular aggregates from a true solution and directing the self-assembly process in a pre-defined fashion. The structure of molecular aggregates in the solution can be predicted from fluorescence correlation spectroscopy (FCS) and dynamic light scattering (DLS) analysis. On the other hand, the morphology of the aggregates can also be visualized through electron microscopy. Nevertheless, a direct correlation between emission from molecular aggregates in the aqueous dispersion and their morphology obtained through a solid-state characterization is missing. In the present study, we decipher the sequential evolution of molecular nanofibers from solution to spherical and oblong-shaped nanoparticles through the variation of solvent polarity, adjusting the <a>hydrophobic-hydrophilic interactions</a>. The intriguing case of molecular self-assembly is elucidated employing a newly designed π-conjugated thiophene derivative (TPAn) through a combination of steady-state absorption, emission measurements, FCS, and electron microscopy. The FCS analysis and microscopy results infer that small-sized nanofibers in the dispersion are further agglomerated, resulting in a network of nanofibers upon solvent evaporation. <a>The evolution of organic nanofibers and subtle control over the self-assembly process demonstrated in the current investigation provides a general paradigm to correlate the size, shape, and emission properties of diverse fluorescent molecular aggregates in complex heterogeneous media, including a human cell. </a>

Controlled Self-Assembly of Collagen Fibrils by an Automated Dialysis System

2006 ◽  
Vol 128 (5) ◽  
pp. 792-796 ◽  
Author(s):  
Stefan Strasser ◽  
Albert Zink ◽  
Wolfgang M. Heckl ◽  
Stefan Thalhammer
Keyword(s):  
Self Assembly ◽  
Collagen Type ◽  
Diffusion Rate ◽  
Collagen Fibrils ◽  
The Self ◽  
Automated System ◽  
Computer Assisted ◽  
Type I ◽  
Assembly Process ◽  
Self Assembled

In vitro self-assembled collagen fibrils form a variety of different structures during dialysis. The self-assembly is dependent on several parameters, such as concentrations of collagen and α1-acid glycoprotein, temperature, dialysis time, and the acid concentration. For a detailed understanding of the assembly pathway and structural features like banding pattern or mechanical properties it is necessary to study single collagen fibrils. In this work we present a fully automated system to control the permeation of molecules through a membrane like a dialysis tubing. This allows us to ramp arbitrary diffusion rate profiles during the self-assembly process of macromolecules, such as collagen. The system combines a molecular sieving method with a computer assisted control system for measuring process variables. With the regulation of the diffusion rate it is possible to control and manipulate the collagen self-assembly process during the whole process time. Its performance is demonstrated by the preparation of various collagen type I fibrils and native collagen type II fibrils. The combination with the atomic force microscope (AFM) allows a high resolution characterization of the self-assembled fibrils. In principle, the represented system can be also applied for the production of other biomolecules, where a dialysis enhanced self-assembly process is used.

scholarly journals Homochiral Supramolecular Thin Film from Self-Assembly of Achiral Triarylamine Molecules by Circularly Polarized Light

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 402
Author(s):  
Changjun Park ◽  
Jinhee Lee ◽  
Taehyoung Kim ◽  
Jaechang Lim ◽  
Jeyoung Park ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Self Assembly ◽  
Polarized Light ◽  
Building Blocks ◽  
The Self ◽  
Assembly Process ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Self Assembled

Here, we report the formation of homochiral supramolecular thin film from achiral molecules, by using circularly polarized light (CPL) only as a chiral source, on the condition that irradiation of CPL does not induce a photochemical change of the achiral molecules. Thin films of self-assembled structures consisting of chiral supramolecular fibrils was obtained from the triarylamine derivatives through evaporation of the self-assembled triarylamine solution. The homochiral supramolecular helices with the desired handedness was achieved by irradiation of circularly polarized visible light during the self-assembly process, and the chiral stability of supramolecular self-assembled product was achieved by photopolymerization of the diacetylene moieties at side chains of the building blocks, with irradiation of circularly polarized ultraviolet light. This work provides a novel methodology for the generation of homochiral supramolecular thin film from the corresponding achiral molecules.

Molecular dynamics simulations of self-assembled peptide amphiphile based cylindrical nanofibers

RSC Advances ◽  
2015 ◽  
Vol 5 (82) ◽  
pp. 66582-66590 ◽  
Author(s):  
E. Deniz Tekin
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Structural Properties ◽  
Self Assembly ◽  
The Self ◽  
Assembly Process ◽  
Peptide Amphiphile ◽  
Self Assembled ◽  
Dynamics Simulations

We carried out united-atom molecular dynamics simulations to understand the structural properties of peptide amphiphile (PA)-based cylindrical nanofibers and the factors that play a role in the “Self-Assembly” process on some specific nanofibers.

Nanoscale Self-Assembly Using Ion and Electron Beam Techniques: A Rapid Review

MRS Advances ◽  
2020 ◽  
Vol 5 (64) ◽  
pp. 3507-3520
Author(s):  
Chunhui Dai ◽  
Kriti Agarwal ◽  
Jeong-Hyun Cho
Keyword(s):  
Electron Beam ◽  
Self Assembly ◽  
Ion Beam ◽  
Three Dimensional ◽  
The Self ◽  
Stress Generation ◽  
Rapid Review ◽  
High Yield ◽  
3D Nanostructures ◽  
Self Assembled

AbstractNanoscale self-assembly, as a technique to transform two-dimensional (2D) planar patterns into three-dimensional (3D) nanoscale architectures, has achieved tremendous success in the past decade. However, an assembly process at nanoscale is easily affected by small unavoidable variations in sample conditions and reaction environment, resulting in a low yield. Recently, in-situ monitored self-assembly based on ion and electron irradiation has stood out as a promising candidate to overcome this limitation. The usage of ion and electron beam allows stress generation and real-time observation simultaneously, which significantly enhances the controllability of self-assembly. This enables the realization of various complex 3D nanostructures with a high yield. The additional dimension of the self-assembled 3D nanostructures opens the possibility to explore novel properties that cannot be demonstrated in 2D planar patterns. Here, we present a rapid review on the recent achievements and challenges in nanoscale self-assembly using electron and ion beam techniques, followed by a discussion of the novel optical properties achieved in the self-assembled 3D nanostructures.

Sign in / Sign up

Export Citation Format

Share Document