GOLD NANOPARTICLE-INCORPORATED POLYELECTROLYTE MULTILAYER FOR SENSITIVE ELECTROCHEMICAL IMMUNOSENSING

COSMOS ◽  
2010 ◽  
Vol 06 (02) ◽  
pp. 197-205
Author(s):  
WEIHUA HU ◽  
CHANG MING LI
Keyword(s):  
Storage Stability ◽  
Dynamic Range ◽  
Layer By Layer ◽  
Polyelectrolyte Multilayer ◽  
Redox Species ◽  
Protein Resistance ◽  
Amperometric Immunosensor ◽  
Capture Antibody ◽  
Electrochemical Immunosensing

Reported was a novel amperometric immunosensor based on layer-by-layer (LbL) assembled polyethylenimine/gold nanoparticles/poly (acrylic acid) (PEI/AuNPs/PAA) multilayer. The assembly process was in situ monitored by surface plasmon resonance (SPR) technique. Anti-goat IgG as a capture antibody was covalently immobilized on the outermost PAA layer of the multilayer to construct an immunosensor. A target protein, goat IgG was electrochemically detected with alkaline phosphatase-conjugated anti-goat IgG (ALP-anti-goat IgG) as a recognition antibody. Electrochemical investigations suggest that the incorporation of AuNPs facilitates the electron transfer between the underlying electrode and the redox species in solution, and thus enhances the electrochemical signals and in turn improves the immunosensing performance. A detection limit of 100 pg mL-1 with a dynamic range of five orders of magnitude was achieved. Due to the protein-friendly environment and the protein resistance of the polyelectrolyte multilayer, the resulting immunosensor demonstrates excellent storage stability, satisfying assay specificity.

Polyelectrolyte Multi-Layered Griseofulvin Nanoparticles: Conventional versus Continuous In-Situ Layer-by-Layer Fabrication

2021 ◽  
Vol 21 (11) ◽  
pp. 5611-5621
Author(s):  
Sumayah Abdul-Jabbar ◽  
Gary P. Martin ◽  
Luigi G. Martini ◽  
Jayne Lawrence ◽  
Paul G. Royall
Keyword(s):  
Conventional Method ◽  
Electrostatic Interactions ◽  
De Novo ◽  
Particle Surface ◽  
Drug Carriers ◽  
Water Soluble ◽  
Layer By Layer ◽  
Polyelectrolyte Multilayer ◽  
Potential Applications

Polyelectrolyte multilayers are promising drug carriers with potential applications in the delivery of poorly soluble drugs. Furthermore, the polyelectrolyte multilayer contributes towards electrostatic interactions, which enhances the physical and chemical stability of colloids when compared to those prepared by other approaches. The aim of this work was to generate a polyelectrolyte multilayer on well characterised nanoparticles of the poorly water-soluble drug, griseofulvin. Griseofulvin (GF) nanoparticles (300 nm) were produced by wet bead milling, bearing a negative surface charge due to the use of poly(sodium 4-styrenesulfonate) (PSS) as a stabiliser. Six further layers of alternating chitosan and PSS polyelectrolyte multilayer were successfully generated at the particle surface either via use of: (1) the conventional method of adding excess coating polymer followed by centrifugation, or (2) the continuous in situ approach of adding sufficient amount of coating polymer. The continuous in situ method was designed de novo by the consecutive addition of polymers under high shear rate mixing. In comparison to the continuous in situ method, the conventional method yielded nanoparticles of smaller size (282 ±9 nm vs. 497 ±34 nm) and higher stability by maintaining its size for 6 months. In conclusion, the parent griseofulvin nanosuspension proved to be a suitable candidate for the polyelectrolyte multilayer fabrication providing an avenue for a bespoke formulation with versatile and potentially enhanced drug delivery properties.

Epitaxial growth manner and structure of superconducting oxide films

1990 ◽  
Vol 48 (4) ◽  
pp. 2-3
Author(s):  
Yoshichika Bando ◽  
Takahito Terashima ◽  
Kenji Iijima ◽  
Kazunuki Yamamoto ◽  
Kazuto Hirata ◽  
...  
Keyword(s):  
Ultrathin Films ◽  
Film Surface ◽  
High Energy ◽  
Epitaxial Films ◽  
Layer By Layer ◽  
Initial Growth ◽  
In Situ Growth ◽  
High Quality ◽  
Activated Reactive Evaporation

The high quality thin films of high-Tc superconducting oxide are necessary for elucidating the superconducting mechanism and for device application. The recent trend in the preparation of high-Tc films has been toward “in-situ” growth of the superconducting phase at relatively low temperatures. The purpose of “in-situ” growth is to attain surface smoothness suitable for fabricating film devices but also to obtain high quality film. We present the investigation on the initial growth manner of YBCO by in-situ reflective high energy electron diffraction (RHEED) technique and on the structural and superconducting properties of the resulting ultrathin films below 100Å. The epitaxial films have been grown on (100) plane of MgO and SrTiO, heated below 650°C by activated reactive evaporation. The in-situ RHEED observation and the intensity measurement was carried out during deposition of YBCO on the substrate at 650°C. The deposition rate was 0.8Å/s. Fig. 1 shows the RHEED patterns at every stage of deposition of YBCO on MgO(100). All the patterns exhibit the sharp streaks, indicating that the film surface is atomically smooth and the growth manner is layer-by-layer.

Oblique-incidence Reflectivity Difference (OI-RD) and Leed Studies of Adsorption and Growth of Xe on Nb(110)

2003 ◽  
Vol 780 ◽  
Author(s):  
P. Thomas ◽  
E. Nabighian ◽  
M.C. Bartelt ◽  
C.Y. Fong ◽  
X.D. Zhu
Keyword(s):  
Transition Layer ◽  
Layer Growth ◽  
Flow Mode ◽  
Layer By Layer ◽  
Zeroth Order ◽  
Step Flow ◽  
Low Energy Electron Diffraction ◽  
Oriented Film ◽  
Low Energy Electron

AbstractWe studied adsorption, growth and desorption of Xe on Nb(110) using an in-situ obliqueincidence reflectivity difference (OI-RD) technique and low energy electron diffraction (LEED) from 32 K to 100 K. The results show that Xe grows a (111)-oriented film after a transition layer is formed on Nb(110). The transition layer consists of three layers. The first two layers are disordered with Xe-Xe separation significantly larger than the bulk value. The third monolayer forms a close packed (111) structure on top of the tensile-strained double layer and serves as a template for subsequent homoepitaxy. The adsorption of the first and the second layers are zeroth order with sticking coefficient close to one. Growth of the Xe(111) film on the transition layer proceeds in a step flow mode from 54K to 40K. At 40K, an incomplete layer-by-layer growth is observed while below 35K the growth proceeds in a multilayer mode.

In situ switching layer-by-layer assembly: one-pot rapid layer assembly via alternation of reductive and oxidative electropolymerization

2013 ◽  
Vol 49 (61) ◽  
pp. 6879 ◽  
Author(s):  
Mao Li ◽  
Jian Zhang ◽  
Hai-Jing Nie ◽  
Meiyong Liao ◽  
Liwen Sang ◽  
...  
Keyword(s):  
Layer By Layer ◽  
One Pot ◽  
Layer By Layer Assembly ◽  
Layer Assembly ◽  
Switching Layer

Rheed Studies of a-Axis Oriented DyBa2Cu3O7 Films Grown by All-MBE

1997 ◽  
Vol 502 ◽  
Author(s):  
Ivan Bozovic ◽  
J. N. Eckstein ◽  
Natasha Bozovic ◽  
J. O'Donnell
Keyword(s):  
Phase Transitions ◽  
Secondary Phase ◽  
Atomic Layer ◽  
High Energy ◽  
Layer By Layer ◽  
Growth Modes ◽  
Flow Surface ◽  
Surface Phase Transitions

ABSTRACTReal-time, in-situ surface monitoring by reflection high-energy electron diffraction (RHEED) has been the key enabling component of atomic-layer-by-layer molecular beam epitaxy (ALL-MBE) of complex oxides. RHEED patterns contain information on crystallographic arrangements and long range order on the surface; this can be made quantitative with help of numerical simulations. The dynamics of RHEED patterns and intensities reveal a variety of phenomena such as nucleation and dissolution of secondary-phase precipitates, switching between growth modes (layer-by-layer, step-flow), surface phase transitions (surface reconstruction, roughening, and even phase transitions induced by the electron beam itself), etc. Some of these phenomena are illustrated here, using as a case study our recent growth of atomically smooth a-axis oriented DyBa2Cu3O7 films.

Fabrication of Polycrystalline Silicon on Glass from Fluorinated Precursors with the Aid of Atomic Hydrogen

1995 ◽  
Vol 403 ◽  
Author(s):  
T. Akasaka ◽  
D. He ◽  
I. Shimizu
Keyword(s):  
Thin Films ◽  
Atomic Hydrogen ◽  
Polycrystalline Silicon ◽  
In Situ Observation ◽  
Layer By Layer ◽  
High Quality ◽  
Deposition Parameters ◽  
Columnar Grains ◽  
Step Growth

AbstractHigh quality polycrystalline silicon was made on glass from fluorinated precursors by two step growth, i.e., (1) formation of seed crystals on glass by layer-by-layer(LL) technique and (2) grain-growth on the seeds. In LL technique, deposition of ultra-thin films and treatment with atomic hydrogen was repeated alternately. Columnar grains with 200 nm dia were grown epitaxy-like on the seeds by optimizing the deposition parameters under in situ observation with spectroscopic ellipsometry.

Formation of Polyelectrolyte Multilayer Architectures with Embedded DMPC Studied in Situ by Neutron Reflectometry

Langmuir ◽  
2005 ◽  
Vol 21 (18) ◽  
pp. 8509-8514 ◽  
Author(s):  
Christophe Delajon ◽  
Thomas Gutberlet ◽  
Roland Steitz ◽  
Helmuth Möhwald ◽  
Rumen Krastev
Keyword(s):  
Neutron Reflectometry ◽  
Polyelectrolyte Multilayer

Effect of Semiconductor and Dye Interfacial Properties in Dye-Sensitized Solar Cells

2001 ◽  
Vol 710 ◽  
Author(s):  
Jin-An He ◽  
Ravi Mosurkal ◽  
Jayant Kumar ◽  
Lian Li ◽  
K. G. Chittibabu ◽  
...  
Keyword(s):  
Solar Cells ◽  
Dye Sensitized Solar Cells ◽  
Passive Layer ◽  
Layer By Layer ◽  
Electron Recombination ◽  
Redox Species ◽  
Interfacial Modification ◽  
Assembly Technique ◽  
Polyelectrolyte Film ◽  
And Control

ABSTRACTThe back recombination processes of electrons from the semiconductor to the oxidized dye and the oxidized redox species can dramatically reduce the efficiency of conventional dyesensitized solar cells (DSSCs). In this work, we have used the electrostatic layer-by-layer (ELBL) assembly technique to specifically manipulate and control the interface between the semiconductor and adsorbed dye layers in DSSCs to potentially minimize this recombination behavior. The interfacial modification has been achieved by applying different combinations and thicknesses of polyelectrolytes using the ELBL method and the performance of the cells has been monitored by measuring the I-V characteristics and the efficiency of the solar cells. The results indicate that an ultrathin polyelectrolyte film, on the order of a few Angstroms, between the semiconductor and the dye layer plays a crucial role on the performance of the solar cell. More specifically, the efficiencies of the DSSCs do not show any improvement after the interfacial treatment when compared to untreated samples. Surprisingly, the efficiency of the cells decreases to some degree, depending on the thickness of the polyelectrolyte films. This suggests that incorporation of a thin (several Angstroms) passive layer between the semiconductor and dye layer in these devices results in an increased resistance of the device and do not significantly reduce the back electron recombination as was originally anticipated. These results show interesting mechanistic information regarding the interfacial interactions of semiconductor/dye interfaces in DSSCs.

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