scholarly journals Biosensors Platform Based on Chitosan/AuNPs/Phthalocyanine Composite Films for the Electrochemical Detection of Catechol. The Role of the Surface Structure

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 2152 ◽  
Author(s):  
Coral Salvo-Comino ◽  
Alfonso González-Gil ◽  
Javier Rodriguez-Valentin ◽  
Celia Garcia-Hernandez ◽  
Fernando Martin-Pedrosa ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Copper Phthalocyanine ◽  
Composite Films ◽  
Layer By Layer ◽  
Transfer Path ◽  
Layer Structures ◽  
Order Of Magnitude ◽  
Lbl Films

Biosensor platforms consisting of layer by layer films combining materials with different functionalities have been developed and used to obtain improved catechol biosensors. Tyrosinase (Tyr) or laccase (Lac) were deposited onto LbL films formed by layers of a cationic linker (chitosan, CHI) alternating with layers of anionic electrocatalytic materials (sulfonated copper phthalocyanine, CuPcS or gold nanoparticles, AuNP). Films with different layer structures were successfully formed. Characterization of surface roughness and porosity was carried out using AFM. Electrochemical responses towards catechol showed that the LbL composites efficiently improved the electron transfer path between Tyr or Lac and the electrode surface, producing an increase in the intensity over the response in the absence of the LbL platform. LbL structures with higher roughness and pore size facilitated the diffusion of catechol, resulting in lower LODs. The [(CHI)-(AuNP)-(CHI)-(CuPcS)]2-Tyr showed an LOD of 8.55∙10−4 μM, which was one order of magnitude lower than the 9.55·10−3 µM obtained with [(CHI)-(CuPcS)-(CHI)-(AuNP)]2-Tyr, and two orders of magnitude lower than the obtained with other nanostructured platforms. It can be concluded that the combination of adequate materials with complementary activity and the control of the structure of the platform is an excellent strategy to obtain biosensors with improved performances.

Morphology characterization of layer-by-layer films from PAH/MA-co-DR13: the role of film thickness

2005 ◽  
Vol 285 (2) ◽  
pp. 544-550 ◽  
Author(s):  
Nara C. de Souza ◽  
Valtencir Zucolotto ◽  
Josmary R. Silva ◽  
Felipe R. Santos ◽  
David S. dos Santos ◽  
...  
Keyword(s):  
Film Thickness ◽  
Layer By Layer ◽  
Morphology Characterization

Epitaxial Iridium Growth on Strontium Titanate

2000 ◽  
Vol 648 ◽  
Author(s):  
Z. Dai ◽  
A.P. Li ◽  
C. Bednarski ◽  
L. I. McCann ◽  
B. Golding
Keyword(s):  
Surface Roughness ◽  
Substrate Surface ◽  
Surface Preparation ◽  
Electron Beam Evaporation ◽  
Layer By Layer ◽  
Epitaxial Relationship ◽  
Ion Channeling ◽  
Substrate Temperatures ◽  
Subsequent Layer

AbstractEpitaxial (100) iridium films have been grown on (100) SrTiO3 (STO) substrates by electron beam evaporation. The epitaxial relationship between the iridium film and STO substrate was determined to be Ir(001)[100]//STO(001)[100]. A systematic study of the role of STO substrate surface preparation, Ir thickness, and substrate temperature on Ir film crystallinity and morpholo- gy has been performed. The best Ir films typically have small Ir(200) XRD linewidths < 0.3 °, surface roughness of 0.2 nm, and low ion channeling yields, χmin≤ 4%, when deposited at 800 °C. Films generally become smoother with better crystallinity when the film thickness approaches 300 nm. A growth mode with initial island formation and subsequent layer-by-layer appears to take place at higher substrate temperatures, whereas at lower temperatures the film grows in a 3D mode.

scholarly journals Simulation of synthetic gecko arrays shearing on rough surfaces

2014 ◽  
Vol 11 (95) ◽  
pp. 20140021 ◽  
Author(s):  
Andrew G. Gillies ◽  
Ronald S. Fearing
Keyword(s):  
Surface Roughness ◽  
Rough Surfaces ◽  
Adhesive System ◽  
Single Fibre ◽  
Order Of Magnitude ◽  
Synthetic Adhesives ◽  
Contact Models ◽  
Nanoscale Features ◽  
The Relationship

To better understand the role of surface roughness and tip geometry in the adhesion of gecko synthetic adhesives, a model is developed that attempts to uncover the relationship between surface feature size and the adhesive terminal feature shape. This model is the first to predict the adhesive behaviour of a plurality of hairs acting in shear on simulated rough surfaces using analytically derived contact models. The models showed that the nanoscale geometry of the tip shape alters the macroscale adhesion of the array of fibres by nearly an order of magnitude, and that on sinusoidal surfaces with amplitudes much larger than the nanoscale features, spatula-shaped features can increase adhesive forces by 2.5 times on smooth surfaces and 10 times on rough surfaces. Interestingly, the summation of the fibres acting in concert shows behaviour much more complex that what could be predicted with the pull-off model of a single fibre. Both the Johnson–Kendall–Roberts and Kendall peel models can explain the experimentally observed frictional adhesion effect previously described in the literature. Similar to experimental results recently reported on the macroscale features of the gecko adhesive system, adhesion drops dramatically when surface roughness exceeds the size and spacing of the adhesive fibrillar features.

scholarly journals Electrochemical and microstructural characterization of platinum supported on glassy carbon

2007 ◽  
Vol 61 (3) ◽  
pp. 135-141
Author(s):  
Sanja Terzic ◽  
Vladislava Jovanovic ◽  
Dusan Tripkovic ◽  
Andrzej Kowal ◽  
Jerzy Stoch
Keyword(s):  
Methanol Oxidation ◽  
Glassy Carbon ◽  
Microstructural Characterization ◽  
Electrochemical Treatment ◽  
Organic Residues ◽  
Remarkable Effect ◽  
Platinum Particles ◽  
Order Of Magnitude

The effect of the electrochemical oxidation of glassy carbon on the deposition of platinum particles and the electrocatalytic activity of platinum supported on oxidized glassy carbon were studied for methanol oxidation in H2SO4 solution. Platinum was potentiostatically deposited from H2SO4 + 6mM H2PtCl6 solution. Glassy carbon was anodically polarized in 1 M NaOH at 1.41 V (SCE) for 35 and 95 s and in 0.5 M H2SO4 at 2V (SCE) for 35; 95 s and 2.25 V for 35 and 95 s. Electrochemical treatment of the GC support leads to a better distribution of platinum on the substrate and has remarkable effect on the activity. The activity of the Pt/GCox electrode for methanol oxidation is larger than that of polycrystalline Pt and by more than one order of magnitude larger than that of a Pt/GC electrode. This increase in activity indicates the pronounced role of the organic residues of the GC support on the properties of Pt particles deposited on glassy carbon.

Role of Silver Doping in the Improvement of Electrical Properties of (Ba,Sr)TiO3 Thin Films

1999 ◽  
Vol 567 ◽  
Author(s):  
Anuranjan Srivastava ◽  
D. Kumar ◽  
Rajiv K. Singh ◽  
Harish Venkataraman ◽  
William R. Eisenstadt
Keyword(s):  
Electrical Properties ◽  
Oxygen Vacancies ◽  
Domain Walls ◽  
Silver Doping ◽  
Order Of Magnitude ◽  
Electrical And Dielectric Properties ◽  
Bst Films ◽  
Fabrication And Characterization

ABSTRACTIn this paper we report the fabrication and characterization of Ag/(Ba,Sr)TiO3 /LaNiO3/LaAlO3 capacitors. All the films, including the top (silver) and bottom (LaNiO3) electrodes, were deposited using a pulsed laser deposition technique. The electrical and dielectric properties of (Ba,Sr)TiO3 capacitors were found to improve significantly by means of silver doping. For example, the leakage current density of a Ag/Ag-doped-(Ba,Sr)TiO3 /LaNiO3/ capacitor was about an order of magnitude lower and dielectric constant was ∼40 % higher than that of a Ag/(Ba,Sr)TiO3 /LaNiO3/capacitor over a range of biases. The improvement in the electrical properties of (Ba,Sr)TiO3 films is believed to be caused by a double role of silver. The first one is associated with the reduced oxygen vacancies due to improved oxygenation of BST films in presence of silver and the second one is associated unpinning effect of domain walls again in presence of silver.

scholarly journals KARAKTERISASI FILM KOMPOSIT ALGINAT DAN KITOSAN

REAKTOR ◽  
2012 ◽  
Vol 14 (2) ◽  
pp. 158 ◽  
Author(s):  
Nur Rokhati ◽  
Bambang Pramudono ◽  
Nyoman Widiasa ◽  
Heru Susanto
Keyword(s):  
Composite Films ◽  
Raw Material ◽  
Layer By Layer ◽  
Permeability Test ◽  
Natural Polymers ◽  
Layer Method ◽  
Degree Of Swelling ◽  
Chitosan Films ◽  
Chitosan Composite

CHARACTERIZATION OF ALGINATE AND CHITOSAN COMPOSITE FILM. Due to the specific characteristics of (thin) films, the use of polymer films in various aplications has singnificantly increased. Alginate and chitosan are natural polymers, which have potential as a raw material for the manufacture of composite films. This paper presents the preparation and characterization of alginate, chitosan and chitosan-alginate composite films. The film characterization included permeability test, degree of swelling, mechanical property, morphology (by SEM), and surface chemistry (by FTIR). The results showed that alginate films have a higher permeability ​​and degree of swelling (DS) than chitosan films. Both permeability and DS decreased with increasing concentration for both alginate and chitosan films. DS experiments showed that the films have the highest DS in water followed by ethanol 95% and ethanol >99.9%, respectively. The mechanical strength of chitosan films was larger than alginate films. Alginate-chitosan composite films prepared by layer by layer method showed better characteristics than the composite films prepared by blending of alginate and chitosan solutions. Meningkatnya aplikasi film polimer di berbagai industri tidak terlepas dari keunggulan yang dimiliki. Alginat dan kitosan merupakan polimer alam yang mempunyai potensi sebagai bahan dasar pembuatan film komposit. Pada penelitian ini dilakukan pembuatan dan karakterisasi film komposit berbasis alginat dan kitosan. Karakterisasi film yang dilakukan meliputi uji: permeabilitas, derajat swelling, mekanik, morfologi (dengan SEM), dan struktur kimia permukaan (dengan FTIR). Hasil penelitian menunjukkan bahwa film alginat mempunyai nilai permeabilitas maupun derajat swelling yang lebih tinggi dibanding dengan film kitosan. Baik pada kitosan maupun alginat memberikan fenomena bahwa semakin besar konsentrasi larutan maka semakin kecil nilai permeabilitas maupun derajat swelling, dengan derajat swelling terhadap air adalah yang  paling besar kemudian diikuti oleh ethanol teknis (± 95%) dan yang terkecil adalah ethanol PA (> 99,9%). Kekuatan mekanik film kitosan lebih besar dibanding dengan film alginat. Film komposit alginat-kitosan yang dibuat dengan metode layer by layer memberikan karakteristik yang lebih baik dibanding dengan film komposit yang dibuat dengan pencampuran larutan alginat dan larutan kitosan.

scholarly journals Nanoparticles in Polyelectrolyte Multilayer Layer-by-Layer (LbL) Films and Capsules—Key Enabling Components of Hybrid Coatings

Coatings ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1131
Author(s):  
Ekaterina V. Lengert ◽  
Semyon I. Koltsov ◽  
Jie Li ◽  
Alexey V. Ermakov ◽  
Bogdan V. Parakhonskiy ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Laser Light ◽  
Inorganic Nanoparticles ◽  
Hybrid Coatings ◽  
Layer By Layer ◽  
Polyelectrolyte Multilayer ◽  
Emerging Trends ◽  
Lbl Films ◽  
Layer Assembly

Originally regarded as auxiliary additives, nanoparticles have become important constituents of polyelectrolyte multilayers. They represent the key components to enhance mechanical properties, enable activation by laser light or ultrasound, construct anisotropic and multicompartment structures, and facilitate the development of novel sensors and movable particles. Here, we discuss an increasingly important role of inorganic nanoparticles in the layer-by-layer assembly—effectively leading to the construction of the so-called hybrid coatings. The principles of assembly are discussed together with the properties of nanoparticles and layer-by-layer polymeric assembly essential in building hybrid coatings. Applications and emerging trends in development of such novel materials are also identified.

Thermal and Mechanical Characterization of PMMA TiO2 Nanocomposites

2009 ◽  
Vol 67 ◽  
pp. 209-214 ◽  
Author(s):  
Niranjan Patra ◽  
Alberto C. Barone ◽  
Marco Salerno ◽  
Gianvito Caputo ◽  
Davide Cozzoli ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Glass Transition ◽  
Transition Temperature ◽  
Mechanical Characterization ◽  
Filler Content ◽  
Composite Films ◽  
Morphological Characterization ◽  
Abrupt Increase ◽  
Nanosized Filler

Hybrid composite films made of an organic polymeric matrix and an inorganic nanosized filler, namely titania prolate nanoparticles, have been prepared and characterized both thermally and mechanically. The filler content has been varied, while still being kept in the regime of unsaturated, homogeneous nanocomposites. On increasing, the filler content there is an abrupt increase in hardness at an intermediate load, while the elastic modulus increases almost linearly. The glass transition temperature is also increased, with a tendency to saturation. The morphological characterization of the films confirms a lack of phase separation, with only a continuous, slight increase in surface roughness, and no major effects on the top film features.

PREPARO E CARACTERIZAÇÃO DE FILMES AUTOMONTADOS DA FTALOCIANINA DE COBRE SULFONADA / PREPARATION AND CHARACTERIZATION OF LAYER-BY-LAYER FILMS OF SULFONATED COPPER PHTHALOCYANINE

2020 ◽  
Vol 6 (9) ◽  
pp. 72780-72787
Author(s):  
Jaqueline Portes Pagnoncelli ◽  
Juliana Cristina Kreutz ◽  
Adonilson dos Reis Freitas ◽  
Luciana Gaffo
Keyword(s):  
Copper Phthalocyanine ◽  
Layer By Layer
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