scholarly journals Nucleation of protein mesocrystals via oriented attachment

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Alexander E. S. Van Driessche ◽  
Nani Van Gerven ◽  
Rick R. M. Joosten ◽  
Wai Li Ling ◽  
Maria Bacia ◽  
...  
Keyword(s):  
Self Assembly ◽  
Building Blocks ◽  
Oriented Attachment ◽  
Great Promise ◽  
Inorganic Systems ◽  
Transmission Electron ◽  
Designer Proteins ◽  
Rate Limit ◽  
The Impact

AbstractSelf-assembly of proteins holds great promise for the bottom-up design and production of synthetic biomaterials. In conventional approaches, designer proteins are pre-programmed with specific recognition sites that drive the association process towards a desired organized state. Although proven effective, this approach poses restrictions on the complexity and material properties of the end-state. An alternative, hierarchical approach that has found wide adoption for inorganic systems, relies on the production of crystalline nanoparticles that become the building blocks of a next-level assembly process driven by oriented attachment (OA). As it stands, OA has not yet been observed for protein systems. Here we employ cryo-transmission electron microscopy (cryoEM) in the high nucleation rate limit of protein crystals and map the self-assembly route at molecular resolution. We observe the initial formation of facetted nanocrystals that merge lattices by means of OA alignment well before contact is made, satisfying non-trivial symmetry rules in the process. As these nanocrystalline assemblies grow larger we witness imperfect docking events leading to oriented aggregation into mesocrystalline assemblies. These observations highlight the underappreciated role of the interaction between crystalline nuclei, and the impact of OA on the crystallization process of proteins.

scholarly journals Nonclassical nucleation of protein mesocrystals via oriented attachment

2020 ◽  
Author(s):  
Alexander E.S. Van Driessche ◽  
Nani Van Gerven ◽  
Rick R.M. Joosten ◽  
Wai Li Ling ◽  
Maria Bacia ◽  
...  
Keyword(s):  
Self Assembly ◽  
Protein Crystallization ◽  
Building Blocks ◽  
Oriented Attachment ◽  
Great Promise ◽  
Inorganic Systems ◽  
Maturation Stages ◽  
Designer Proteins ◽  
Rate Limit ◽  
Classical Mechanism

AbstractSelf-assembly of proteins holds great promise for the bottom-up design and production of synthetic biomaterials. In conventional approaches, designer proteins are pre-programmed with specific recognition sites that drive the association process towards a desired organized state. Although proven effective, this approach poses restrictions on the complexity and material properties of the end-state. An alternative, hierarchical approach that has found wide adoption for inorganic systems, relies on the production of crystalline nanoparticles which in turn become the building blocks of a next-level assembly process driven by oriented attachment (OA). As it stands, OA has not been observed for proteins. Here we employ cryoEM in the high nucleation rate limit of protein crystals and map the self-assembly route at molecular resolution. We observe the initial formation of facetted nanocrystals that merge lattices by means of OA alignment well before contact is made, satisfying non-trivial symmetry rules in the process. The OA mechanism yields crystal morphologies that are not attainable through conventional crystallization routes. Based on these insights we revisit a system of protein crystallization that has long been classified as non-classical, but our data is in direct conflict with that conclusion supporting a classical mechanism that implicates OA. These observations raise further questions about past conclusions for other proteins and illustrate the importance of maturation stages after primary nucleation has taken place.

scholarly journals Amphiphilic Nucleobase-Containing Polypeptide Copolymers—Synthesis and Self-Assembly

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1357
Author(s):  
Michel Nguyen ◽  
Khalid Ferji ◽  
Sébastien Lecommandoux ◽  
Colin Bonduelle
Keyword(s):  
Self Assembly ◽  
Ring Opening ◽  
Building Blocks ◽  
Ring Opening Polymerization ◽  
The Self ◽  
Amphiphilic Copolymers ◽  
Transmission Electron ◽  
Scattering Measurements ◽  
Thymidine Monophosphate ◽  
The Impact

Nucleobase-containing polymers are an emerging class of building blocks for the self-assembly of nanoobjects with promising applications in nanomedicine and biology. Here we present a macromolecular engineering approach to design nucleobase-containing polypeptide polymers incorporating thymine that further self-assemble in nanomaterials. Diblock and triblock copolypeptide polymers were prepared using sequential ring-opening polymerization of γ-Benzyl-l-glutamate N-carboxyanhydride (BLG-NCA) and γ-Propargyl-l-glutamate N-carboxyanhydride (PLG-NCA), followed by an efficient copper(I)-catalyzed azide alkyne cycloaddition (CuAAc) functionalization with thymidine monophosphate. Resulting amphiphilic copolymers were able to spontaneously form nanoobjects in aqueous solutions avoiding a pre-solubilization step with an organic solvent. Upon self-assembly, light scattering measurements and transmission electron microscopy (TEM) revealed the impact of the architecture (diblock versus triblock) on the morphology of the resulted nanoassemblies. Interestingly, the nucleobase-containing nanoobjects displayed free thymine units in the shell that were found available for further DNA-binding.

Role of Pristine and Acid-Functionalized Fullerene on Breaking Dye Aggregates and its Impact on the Efficiency of Solar Cells

2014 ◽  
Vol 67 (5) ◽  
pp. 819
Author(s):  
Syed Mujtaba Shah ◽  
Zafar Iqbal ◽  
Muzaffar Iqbal ◽  
Naila Shahzad ◽  
Amina Hana ◽  
...  
Keyword(s):  
Solar Cells ◽  
Zno Nanoparticles ◽  
Self Assembly ◽  
Zno Nanorods ◽  
Active Material ◽  
Dye Sensitized Solar Cells ◽  
Dye Sensitized ◽  
Transmission Electron ◽  
Sensitized Solar Cells

Porphyrin dyes have an inherent tendency to aggregate. This leads to a self-quenching phenomenon that hinders electron transfer to the conduction band of semiconductors in dye-sensitized solar cells. Self-quenching adversely affects the efficiency of solar cells. Here, we report the interaction of porphyrin with pristine and acid-functionalized fullerene molecules on the surface of ZnO nanoparticles under chemisorbed conditions. Chemisorption of porphyrin only on ZnO nanoparticles instigates aggregation of the porphyrin molecules. These aggregates can be effectively broken by chemisorbing fullerene molecules on the surface of the ZnO nanoparticles. This is due to self-assembly formation processes because of porphyrin–fullerene interactions. The nanohybrid material, consisting of ZnO nanorods, acid-functionalized porphyrin, and fullerene derivatives, was characterized by UV–visible spectroscopy, fourier transform infrared spectroscopy, fluorescence spectroscopy, and transmission electron microscopy. The material generates better performing dye-sensitized solar cells when compared with those fabricated from porphyrin-based photo-active material.

scholarly journals Low-temperature hydrothermal synthesis of hierarchical flower-like CuB2O4 superstructures

2020 ◽  
Vol 14 (2) ◽  
pp. 113-118
Author(s):  
Daniel Ursu ◽  
Anamaria Dabici ◽  
Marinela Miclau ◽  
Nicolae Miclau
Keyword(s):  
Thermal Stability ◽  
Low Temperature ◽  
Self Assembly ◽  
Hydrothermal Solution ◽  
Optical Measurements ◽  
Oriented Attachment ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
One Step

We report for the first time the fabrication of hierarchical ordered superstructure CuB2O4 with flower-like morphology via a one-step, low temperature hydrothermal method. The tetragonal structure of CuB2O4 was determined by X-ray diffraction and high-resolution transmission electron microscopy. Optical measurements attested of the quality of the fabricated CuB2O4 and high temperature X-ray diffraction confirmed its thermal stability up to 600 ?C. The oriented attachment growth and the hierarchical self-assembly of micrometer-sized platelets producing hierarchical superstructures with flower-like morphology are designed by pH of the hydrothermal solution. The excellent band gap, high thermal stability and hierarchical structure of the CuB2O4 are promising for the photovoltaic and photocatalytic applications.

scholarly journals Role of the Global Fund in national HIV/AIDS response in Myanmar: a qualitative study

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Zarni Htun ◽  
Yingxi Zhao ◽  
Hannah Gilbert ◽  
Chunling Lu
Keyword(s):  
Civil Society ◽  
Qualitative Study ◽  
Health System ◽  
Global Fund ◽  
Scale Up ◽  
Building Blocks ◽  
Key Informants ◽  
The Impact ◽  
Hiv Aids

Abstract Background The Global Fund has been a major funding source for HIV/AIDS programs in Myanmar. In this qualitative study, we aim to understand the impact of Global Fund on national HIV/AIDS response in Myanmar during the era of Millennium Development Goals (MDGs). Methods We conducted individual in-depth interviews by recruiting key informants through purposive snowball sampling. The respondents were engaged in the national/subnational response to HIV/AIDS in Myanmar and worked for the United Nations agencies, non-governmental organizations (NGOs), and civil society. Interview questions were organized around the role of Global Fund in strengthening national response to HIV/AIDS in the six building blocks of the Myanmar’s health system. Transcripts from the key informants were synthesized into specific themes through a deductive approach. Results We found that the Global Fund has provided substantial support to (1) finance the national HIV/AIDS response in Myanmar, and (2) strengthen leadership and governance at the central level through improving coordination and collaboration, including more stakeholders (e.g. civil society, NGOs) in decision making process, and catalyzing policy changes on scaling-up key interventions. Yet, its role remains limited in addressing new demands at the township level in terms of capacity building, staffing, and medical supply resulting from rapid scale-up of HIV interventions and decentralization of service delivery in the public sector. Conclusion There was a missed opportunity for Myanmar to capitalize on the use of the Global Fund’s funding to strengthen the health system. Deliberate planning is required to optimize the use of those scarce resources to provide universal coverage for HIV/AIDS.

Effect of Self-Interstitials – Nanovoids Interaction on Two-Dimensional Diffusion and Activation of Implanted B in Si

2005 ◽  
Vol 108-109 ◽  
pp. 395-400 ◽  
Author(s):  
Filippo Giannazzo ◽  
E. Bruno ◽  
S. Mirabella ◽  
G. Impellizzeri ◽  
E. Napolitani ◽  
...  
Keyword(s):  
Thermal Annealing ◽  
Device Fabrication ◽  
Electrical Activation ◽  
High Dose ◽  
Dimensional Diffusion ◽  
Transmission Electron ◽  
Sio2 Mask ◽  
The Impact ◽  
Subsequent Thermal Annealing

In this work, we investigate the effect of performing a high dose 20 keV He+ implant before the implantation of B at low energy (3 keV) in silicon and the subsequent thermal annealing at 800 °C. The implants were performed in laterally confined regions defined by opening windows in a SiO2 mask, in order to evidence the impact on a realistic configuration used in device fabrication. High resolution quantitative scanning capacitance microscopy (SCM) combined with cross-section transmission electron microscopy (XTEM) allowed to clarify the role of the voids distribution produced during the thermal annealing on the diffusion and electrical activation of implanted B in Si. Particular evidence was given to the effect of the uniform nanovoids distribution, which forms in the region between the surface and the buried cavity layer.

scholarly journals Control over size, shape, and photonics of self-assembled organic nanocrystals

2020 ◽  
Author(s):  
Chen Shahar ◽  
Yaron Tidhar ◽  
Yunmin Jung ◽  
Haim Weissman ◽  
Sidney R Cohen ◽  
...  
Keyword(s):  
Self Assembly ◽  
Transient Absorption ◽  
Aqueous Media ◽  
Excitation Energy Transfer ◽  
Building Blocks ◽  
Transient Absorption Spectroscopy ◽  
Organic Nanocrystals ◽  
Femtosecond Transient Absorption ◽  
Transmission Electron ◽  
And Function

Facile fabrication of free-floating organic nanocrystals (ONCs) was achieved via kinetically controlled self-assembly of simple amphiphilic perylene diimide building blocks in aqueous media. The ONCs have a thin rectangular shape, with the aspect ratio that is controlled via organic co-solvent (THF) content. The nanocrystals were characterized in solution by cryogenic transmission electron microscopy (cryo-TEM) and small angle X-ray scattering (SAXS); the ONCs retain their structure upon drying as was evidenced by TEM and AFM. Photophysical studies, including femtosecond transient absorption spectroscopy, revealed a distinct influence of the ONC morphology on their photonic properties (excitation energy transfer was observed only in the high aspect ONCs). Convenient control over structure and function of organic nanocrystals can enhance their utility in new and developed technologies.

scholarly journals Biocatalysis of d,l-Peptide Nanofibrillar Hydrogel

Molecules ◽  
2020 ◽  
Vol 25 (13) ◽  
pp. 2995 ◽  
Author(s):  
Tiziano Carlomagno ◽  
Maria C. Cringoli ◽  
Slavko Kralj ◽  
Marina Kurbasic ◽  
Paolo Fornasiero ◽  
...  
Keyword(s):  
Self Assembly ◽  
Solid Phase ◽  
Building Blocks ◽  
Cd Spectroscopy ◽  
Tem Analysis ◽  
Design Rules ◽  
Self Assembling ◽  
Transmission Electron ◽  
Oscillatory Rheometry ◽  
The Many

Self-assembling peptides are attracting wide interest as biodegradable building blocks to achieve functional nanomaterials that do not persist in the environment. Amongst the many applications, biocatalysis is gaining momentum, although a clear structure-to-activity relationship is still lacking. This work applied emerging design rules to the heterochiral octapeptide sequence His–Leu–DLeu–Ile–His–Leu–DLeu–Ile for self-assembly into nanofibrils that, at higher concentration, give rise to a supramolecular hydrogel for the mimicry of esterase-like activity. The peptide was synthesized by solid-phase and purified by HPLC, while its identity was confirmed by 1H-NMR and electrospray ionization (ESI)-MS. The hydrogel formed by this peptide was studied with oscillatory rheometry, and the supramolecular behavior of the peptide was investigated with transmission electron microscopy (TEM) analysis, circular dichroism (CD) spectroscopy, thioflavin T amyloid fluorescence assay, and attenuated total reflectance (ATR) Fourier-transform infrared (FT-IR) spectroscopy. The biocatalytic activity was studied by monitoring the hydrolysis of p-nitrophenyl acetate (pNPA) at neutral pH, and the reaction kinetics followed an apparent Michaelis–Menten model, for which a Lineweaver–Burk plot was produced to determine its enzymatic parameters for a comparison with the literature. Finally, LC–MS analysis was conducted on a series of experiments to evaluate the extent of, if any, undesired peptide acetylation at the N-terminus. In conclusion, we provide new insights that allow gaining a clearer picture of self-assembling peptide design rules for biocatalysis.

scholarly journals Facile Fabrication of Natural Polyelectrolyte-Nanoclay Composites: Halloysite Nanotubes, Nucleotides and DNA Study

Molecules ◽  
2020 ◽  
Vol 25 (15) ◽  
pp. 3557 ◽  
Author(s):  
Svetlana Batasheva ◽  
Marina Kryuchkova ◽  
Ramil Fakhrullin ◽  
Giuseppe Cavallaro ◽  
Giuseppe Lazzara ◽  
...  
Keyword(s):  
Self Assembly ◽  
Adhesion Force ◽  
Uv Spectroscopy ◽  
Building Blocks ◽  
Halloysite Nanotubes ◽  
Systematic Investigation ◽  
Water Addition ◽  
Transmission Electron ◽  
Evaporation Induced Self Assembly ◽  
Clay Nanotubes

Complexation of biopolymers with halloysite nanotubes (HNTs) can greatly affect their applicability as materials building blocks. Here we have performed a systematic investigation of fabrication of halloysite nanotubes complexes with nucleotides and genomic DNA. The binding of DNA and various nucleotide species (polyAU, UMP Na2, ADP Na3, dATP Na, AMP, uridine, ATP Mg) by halloysite nanotubes was tested using UV-spectroscopy. The study revealed that binding of different nucleotides to the nanoclay varied but was low both in the presence and absence of MgCl2, while MgCl2 facilitated significantly the binding of longer molecules such as DNA and polyAU. Modification of the nanotubes with DNA and nucleotide species was further confirmed by measurements of ζ-potentials. DNA-Mg-modified nanotubes were characterized using transmission electron (TEM), atomic force (AFM) and hyperspectral microscopies. Thermogravimetric analysis corroborated the sorption of DNA by the nanotubes, and the presence of DNA on the nanotube surface was indicated by changes in the surface adhesion force measured by AFM. DNA bound by halloysite in the presence of MgCl2 could be partially released after addition of phosphate buffered saline. DNA binding and release from halloysite nanotubes was tested in the range of MgCl2 concentrations (10–100 mM). Even low MgCl2 concentrations significantly increased DNA sorption to halloysite, and the binding was leveled off at about 60 mM. DNA-Mg-modified halloysite nanotubes were used for obtaining a regular pattern on a glass surface by evaporation induced self-assembly process. The obtained spiral-like pattern was highly stable and resisted dissolution after water addition. Our results encompassing modification of non-toxic clay nanotubes with a natural polyanion DNA will find applications for construction of gene delivery vehicles and for halloysite self-assembly on various surfaces (such as skin or hair).

scholarly journals Shaping colloidal bananas to reveal biaxial, splay-bend nematic, and smectic phases

Science ◽  
2020 ◽  
Vol 369 (6506) ◽  
pp. 950-955
Author(s):  
Carla Fernández-Rico ◽  
Massimiliano Chiappini ◽  
Taiki Yanagishima ◽  
Heidi de Sousa ◽  
Dirk G. A. L. Aarts ◽  
...  
Keyword(s):  
Phase Behavior ◽  
Self Assembly ◽  
Colloidal Particles ◽  
Functional Materials ◽  
Building Blocks ◽  
Develop Model ◽  
Smectic Phases ◽  
Particle Level ◽  
Nematic Phases ◽  
The Impact

Understanding the impact of curvature on the self-assembly of elongated microscopic building blocks, such as molecules and proteins, is key to engineering functional materials with predesigned structure. We develop model “banana-shaped” colloidal particles with tunable dimensions and curvature, whose structure and dynamics are accessible at the particle level. By heating initially straight rods made of SU-8 photoresist, we induce a controllable shape deformation that causes the rods to buckle into banana-shaped particles. We elucidate the phase behavior of differently curved colloidal bananas using confocal microscopy. Although highly curved bananas only form isotropic phases, less curved bananas exhibit very rich phase behavior, including biaxial nematic phases, polar and antipolar smectic-like phases, and even the long-predicted, elusive splay-bend nematic phase.

Sign in / Sign up

Export Citation Format

Share Document