scholarly journals Reversible changes in the orientation of gold nanorod arrays on polymer brushes

2020 ◽  
Vol 2 (9) ◽  
pp. 3798-3803 ◽  
Author(s):  
Yu Sekizawa ◽  
Hideyuki Mitomo ◽  
Mizuki Nihei ◽  
Satoshi Nakamura ◽  
Yusuke Yonamine ◽  
...  
Keyword(s):  
Polymer Brushes ◽  
Electrostatic Interactions ◽  
Gold Nanorod ◽  
Nanorod Arrays ◽  
Solution Ph ◽  
Anionic Polymer

Gold nanorod (GNR) arrays were prepared by GNR attachment on anionic polymer brushes via electrostatic interactions and their orientation reversibly changed by the modulation of interactions between GNRs and polymers via changes in the solution pH.

Strategy for Finely Aligned Gold Nanorod Arrays Using Polymer Brushes as a Template

Langmuir ◽  
2020 ◽  
Vol 36 (13) ◽  
pp. 3590-3599 ◽  
Author(s):  
Satoshi Nakamura ◽  
Hideyuki Mitomo ◽  
Yu Sekizawa ◽  
Takeshi Higuchi ◽  
Yasutaka Matsuo ◽  
...  
Keyword(s):  
Polymer Brushes ◽  
Gold Nanorod ◽  
Nanorod Arrays

scholarly journals Adsorptive and Coagulative Removal of Trace Metals from Water Using Surface Modified Sawdust-Based Cellulose Nanocrystals

J ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 193-205
Author(s):  
Opeyemi A. Oyewo ◽  
Sam Ramaila ◽  
Lydia Mavuru ◽  
Taile Leswifi ◽  
Maurice S. Onyango
Keyword(s):  
Trace Metals ◽  
Adsorption Capacity ◽  
Cellulose Nanocrystals ◽  
Inductively Coupled Plasma ◽  
Electrostatic Interactions ◽  
Natural Waters ◽  
Maximum Adsorption Capacity ◽  
Solution Ph ◽  
Major Drawback ◽  
Surface Modified

The presence of toxic metals in surface and natural waters, even at trace levels, poses a great danger to humans and the ecosystem. Although the combination of adsorption and coagulation techniques has the potential to eradicate this problem, the use of inappropriate media remains a major drawback. This study reports on the application of NaNO2/NaHCO3 modified sawdust-based cellulose nanocrystals (MCNC) as both coagulant and adsorbent for the removal of Cu, Fe and Pb from aqueous solution. The surface modified coagulants, prepared by electrostatic interactions, were characterized using Fourier transform infrared, X-ray diffraction (XRD), and scanning electron microscopy/energy-dispersive spectrometry (SEM/EDS). The amount of coagulated/adsorbed trace metals was then analysed using inductively coupled plasma atomic emission spectroscopy (ICP-AES). SEM analysis revealed the patchy and distributed floccules on Fe-flocs, which was an indication of multiple mechanisms responsible for Fe removal onto MCNC. A shift in the peak position attributed to C2H192N64O16 from 2θ = 30 to 24.5° occurred in the XRD pattern of both Pb- and Cu-flocs. Different process variables, including initial metal ions concentration (10–200 mg/L), solution pH (2–10), and temperature (25–45 °C) were studied in order to investigate how they affect the reaction process. Both Cu and Pb adsorption followed the Langmuir isotherm with a maximum adsorption capacity of 111.1 and 2.82 mg/g, respectively, whereas the adsorption of Fe was suggestive of a multilayer adsorption process; however, Fe Langmuir maximum adsorption capacity was found to be 81.96 mg/g. The sequence of trace metals removal followed the order: Cu > Fe > Pb. The utilization of this product in different water matrices is an effective way to establish their robustness.

Ultrahigh surface sensitivity of deposited gold nanorod arrays for nanoplasmonic biosensing

2021 ◽  
Vol 23 ◽  
pp. 101046
Author(s):  
Abdul Rahim Ferhan ◽  
Youngkyu Hwang ◽  
Mohammed Shahrudin Bin Ibrahim ◽  
Shikhar Anand ◽  
Ahram Kim ◽  
...  
Keyword(s):  
Gold Nanorod ◽  
Nanorod Arrays ◽  
Surface Sensitivity

scholarly journals Adsorption of Lysozyme Into a Charged Confining Pore

2021 ◽  
Author(s):  
Sidney Carvalho ◽  
Ralf Metzler ◽  
Andrey Cherstvy ◽  
Daniel Caetano
Keyword(s):  
Electrostatic Interactions ◽  
Active Sites ◽  
Coarse Grained ◽  
Pore Surface ◽  
Solution Ph ◽  
Coarse Grained Model ◽  
Egg White Lysozyme ◽  
Constant Ph ◽  
Pka Shift ◽  
Effects Of Ph

Several applications arise from the confinement of proteins on surfaces since their stability and biological activity are enhanced. It is also known that the way a protein adsorbs on the surface is important for its biological function since its active sites should not be obstructed. In this study, the adsorption properties of hen egg-white Lysozyme, HEWL, into a negatively charged silica pore is examined employing a coarse-grained model and constant-pH Monte Carlo simulations. The role of electrostatic interactions is taken into account when including the Debye-Hueckel potentials into the Ca structure-based model. We evaluate the effects of pH, salt concentration, and pore radius on the protein preferential orientation and spatial distribution of its residues regarding the pore surface. By mapping the residues that stay closer to the pore surface, we find the increase of pH leads to orientational changes of the adsorbed protein when the solution pH gets closer to the HEWL isoelectric point. At these conditions, the pKa shift of these important residues caused by the adsorption into the charged confining surface results in a HEWL charge distribution that stabilizes the adsorption in the observed protein orientation. We compare our observations to the results of pKa shift for HEWL available in the literature and to some experimental data.

scholarly journals Silver-Nanoparticle-Decorated Gold Nanorod Arrays via Bioinspired Polydopamine Coating as Surface-Enhanced Raman Spectroscopy (SERS) Platforms

Coatings ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 198 ◽  
Author(s):  
Mehmet Yilmaz
Keyword(s):  
Raman Spectroscopy ◽  
Deposition Time ◽  
Surface Enhanced Raman Spectroscopy ◽  
Gold Nanorod ◽  
Nanorod Arrays ◽  
Plasmonic Material ◽  
Relative Standard ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Controlled Deposition

The controlled deposition of nanoparticles onto 3-D nanostructured films is still facing challenges due to the uncontrolled aggregation of colloidal nanoparticles. In the context of this study, a simple yet effective approach is demonstrated to decorate the silver nanoparticles (AgNP) onto the 3-D and anisotropic gold nanorod arrays (GNAs) through a bioinspired polydopamine (PDOP) coating to fabricate surface-enhanced Raman spectroscopy (SERS) platforms. Since the Raman reporter molecules (methylene blue, MB, 10 µM) were not adsorbed directly on the surface of the plasmonic material, a remarkable decrease in SERS signals was detected for the PDOP-coated GNAs (GNA@PDOP) platforms. However, after uniform and well-controlled AgNP decoration on the GNA@PDOP (GNA@PDOP@AgNP), huge enhancement was observed in SERS signals from the resultant platform due to the synergistic action which originated from the interaction of GNAs and AgNPs. I also detected that PDOP deposition time (i.e., PDOP film thickness) is the dominant parameter that determines the SERS activity of the final system and 30 min of PDOP deposition time (i.e., 3 nm of PDOP thickness) is the optimum value to obtain the highest SERS signal. To test the reproducibility of GNA@PDOP@AgNP platforms, relative standard deviation (RSD) values for the characteristic peaks of MB were found to be less than 0.17, demonstrating the acceptable reproducibility all over the proposed platform. This report suggests that GNA@PDOP@AgNP system may be used as a robust platform for practical SERS applications.

Self-Assembly of Vertically Aligned Gold Nanorod Arrays on Patterned Substrates

2012 ◽  
Vol 51 (35) ◽  
pp. 8732-8735 ◽  
Author(s):  
Thibaut Thai ◽  
Yuanhui Zheng ◽  
Soon Hock Ng ◽  
Stephen Mudie ◽  
Matteo Altissimo ◽  
...  
Keyword(s):  
Self Assembly ◽  
Gold Nanorod ◽  
Nanorod Arrays ◽  
Patterned Substrates ◽  
Vertically Aligned

Fabrication of gold nanorod arrays by templating from porous alumina

2005 ◽  
Vol 16 (10) ◽  
pp. 2275-2281 ◽  
Author(s):  
Dusan Losic ◽  
Joe G Shapter ◽  
James G Mitchell ◽  
Nicolas H Voelcker
Keyword(s):  
Porous Alumina ◽  
Gold Nanorod ◽  
Nanorod Arrays

scholarly journals Coarse-grained dynamic RNA titration simulations

2019 ◽  
Vol 9 (3) ◽  
pp. 20180066 ◽  
Author(s):  
S. Pasquali ◽  
E. Frezza ◽  
F. L. Barroso da Silva
Keyword(s):  
Electrostatic Interactions ◽  
Molecular Organization ◽  
Coarse Grained ◽  
Solution Ph ◽  
Dynamic Simulations ◽  
Rna Molecules ◽  
Coarse Grained Model ◽  
Constant Ph ◽  
Conformational Plasticity ◽  
And Function

Electrostatic interactions play a pivotal role in many biomolecular processes. The molecular organization and function in biological systems are largely determined by these interactions. Owing to the highly negative charge of RNA, the effect is expected to be more pronounced in this system. Moreover, RNA base pairing is dependent on the charge of the base, giving rise to alternative secondary and tertiary structures. The equilibrium between uncharged and charged bases is regulated by the solution pH, which is therefore a key environmental condition influencing the molecule’s structure and behaviour. By means of constant-pH Monte Carlo simulations based on a fast proton titration scheme, coupled with the coarse-grained model HiRE-RNA, molecular dynamic simulations of RNA molecules at constant pH enable us to explore the RNA conformational plasticity at different pH values as well as to compute electrostatic properties as local p K a values for each nucleotide.

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