scholarly journals Polyelectrolyte Based Sensors as Key to Achieve Quantitative Electronic Tongues: Detection of Triclosan on Aqueous Environmental Matrices

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 640
Author(s):  
Cátia Magro ◽  
Paulo Zagalo ◽  
João Pereira-da-Silva ◽  
Eduardo Pires Mateus ◽  
Alexandra Branco Ribeiro ◽  
...  
Keyword(s):  
Continuous Monitoring ◽  
Mineral Water ◽  
Electronic Tongue ◽  
Principal Component ◽  
Electrical Impedance Spectroscopy ◽  
Layer By Layer ◽  
Environmental Matrices ◽  
Film Stability ◽  
Lbl Films ◽  
Water And Wastewater

Triclosan (TCS) is a bacteriostatic used in household items that promotes antimicrobial resistance and endocrine disruption effects both to humans and biota, raising health concerns. In this sense, new devices for its continuous monitoring in complex matrices are needed. In this work, sensors, based on polyelectrolyte layer-by-layer (LbL) films prepared onto gold interdigitated electrodes (IDE), were studied. An electronic tongue array, composed of (polyethyleneimine (PEI)/polysodium 4-styrenesulfonate (PSS))5 and (poly(allylamine hydrochloride/graphene oxide)5 LbL films together with gold IDE without coating were used to detect TCS concentrations (10−15–10−5 M). Electrical impedance spectroscopy was used as means of transduction and the obtained data was analyzed by principal component analysis (PCA). The electronic tongue was tested in deionized water, mineral water and wastewater matrices showing its ability to (1) distinguish between TCS doped and non-doped solutions and (2) sort out the TCS range of concentrations. Regarding film stability, strong polyelectrolytes, as (PEI/PSS)n, presented more firmness and no significant desorption when immersed in wastewater. Finally, the PCA data of gold IDE and (PEI/PSS)5 sensors, for the mineral water and wastewater matrices, respectively, showed the ability to distinguish both matrices. A sensitivity value of 0.19 ± 0.02 per decade to TCS concentration and a resolution of 0.13 pM were found through the PCA second principal component.

scholarly journals Electronic Tongue Based on Nanostructured Hybrid Films of Gold Nanoparticles and Phthalocyanines for Milk Analysis

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Luiza A. Mercante ◽  
Vanessa P. Scagion ◽  
Adriana Pavinatto ◽  
Rafaela C. Sanfelice ◽  
Luiz H. C. Mattoso ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Chemical Sensors ◽  
Film Growth ◽  
Electronic Tongue ◽  
Principal Component ◽  
Inorganic Materials ◽  
Milk Analysis ◽  
Layer By Layer ◽  
Nanostructured Films ◽  
Lbl Films

The use of gold nanoparticles combined with other organic and inorganic materials for designing nanostructured films has demonstrated their versatility for various applications, including optoelectronic devices and chemical sensors. In this study, we reported the synthesis and characterization of gold nanoparticles stabilized with poly(allylamine hydrochloride) (Au@PAH NPs), as well as the capability of this material to form multilayer Layer-by-Layer (LbL) nanostructured films with metal tetrasulfonated phthalocyanines (MTsPc). Film growth was monitored by UV-Vis absorption spectroscopy, atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR). Once LbL films have been applied as active layers in chemical sensors, Au@PAH/MTsPc and PAH/MTsPc LbL films were used in an electronic tongue system for milk analysis regarding fat content. The capacitance data were treated using Principal Component Analysis (PCA), revealing the role played by the gold nanoparticles on the LbL films electrical properties, enabling this kind of system to be used for analyzing complex matrices such as milk without any prior pretreatment.

scholarly journals Thermally Stimulated Desorption Optical Fiber-Based Interrogation System: An Analysis of Graphene Oxide Layers’ Stability

Photonics ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 70
Author(s):  
Maria Raposo ◽  
Carlota Xavier ◽  
Catarina Monteiro ◽  
Susana Silva ◽  
Orlando Frazão ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Optical Fiber ◽  
Optical Fiber Sensor ◽  
Layer By Layer ◽  
Film Stability ◽  
A Value ◽  
Device Reliability ◽  
Sensor Devices ◽  
Lbl Films ◽  
The Stability

Thin graphene oxide (GO) film layers are being widely used as sensing layers in different types of electrical and optical sensor devices. GO layers are particularly popular because of their tuned interface reflectivity. The stability of GO layers is fundamental for sensor device reliability, particularly in complex aqueous environments such as wastewater. In this work, the stability of GO layers in layer-by-layer (LbL) films of polyethyleneimine (PEI) and GO was investigated. The results led to the following conclusions: PEI/GO films grow linearly with the number of bilayers as long as the adsorption time is kept constant; the adsorption kinetics of a GO layer follow the behavior of the adsorption of polyelectrolytes; and the interaction associated with the growth of these films is of the ionic type since the desorption activation energy has a value of 119 ± 17 kJ/mol. Therefore, it is possible to conclude that PEI/GO films are suitable for application in optical fiber sensor devices; most importantly, an optical fiber-based interrogation setup can easily be adapted to investigate in situ desorption via a thermally stimulated process. In addition, it is possible to draw inferences about film stability in solution in a fast, reliable way when compared with the traditional ones.

scholarly journals Discrimination of Milks with a Multisensor System Based on Layer-by-Layer Films

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2716 ◽  
Author(s):  
Coral Salvo-Comino ◽  
Celia García-Hernández ◽  
Cristina García-Cabezón ◽  
Maria Rodríguez-Méndez
Keyword(s):  
Copper Phthalocyanine ◽  
Electronic Tongue ◽  
Principal Component ◽  
Sensor System ◽  
Galactose Oxidase ◽  
Milk Analysis ◽  
Layer By Layer ◽  
Additional Information ◽  
Milk Samples ◽  
Calibration Models

A nanostructured electrochemical bi-sensor system for the analysis of milks has been developed using the layer-by-layer technique. The non-enzymatic sensor [CHI+IL/CuPcS]2, is a layered material containing a negative film of the anionic sulfonated copper phthalocyanine (CuPcS) acting as electrocatalytic material, and a cationic layer containing a mixture of an ionic liquid (IL) (1-butyl-3-methylimidazolium tetrafluoroborate) that enhances the conductivity, and chitosan (CHI), that facilitates the enzyme immobilization. The biosensor ([CHI+IL/CuPcS]2-GAO) results from the immobilization of galactose oxidase on the top of the LbL layers. FTIR, UV–vis, and AFM have confirmed the proposed structure and cyclic voltammetry has demonstrated the amplification caused by the combination of materials in the film. Sensors have been combined to form an electronic tongue for milk analysis. Principal component analysis has revealed the ability of the sensor system to discriminate between milk samples with different lactose content. Using a PLS-1 calibration models, correlations have been found between the voltammetric signals and chemical parameters measured by classical methods. PLS-1 models provide excellent correlations with lactose content. Additional information about other components, such as fats, proteins, and acidity, can also be obtained. The method developed is simple, and the short response time permits its use in assaying milk samples online.

Use of an electronic tongue in the assessment of highly diluted systems

2021 ◽  
Vol 10 (36) ◽  
pp. 104-107
Author(s):  
Mateus Silva Laranjeira ◽  
Marilisa Guimarães Lara ◽  
Marco Vinicius Chaud ◽  
Olney Leite Fontes ◽  
Antônio Riul Jr
Keyword(s):  
Ultrathin Films ◽  
Electronic Tongue ◽  
Principal Component ◽  
Original Data ◽  
Relevant Information ◽  
Statistical Correlation ◽  
Layer By Layer ◽  
Layer Technique ◽  
Liquid Systems ◽  
Complex Liquid

Introduction: “Eletronic tongue” is a device commonly used in the analysis of tastants, heavy metal ions, fruit juice, wines and also in the development of biosensors [1-3]. Briefly, the e-tongue is constituted by sensing units formed by ultrathin films of distinct materials deposited on gold interdigitated electrodes, which are immersed in liquid samples, followed by impedance spectroscopy measurements [1]. The e-tongue sensor is based on the global selectivity concept, i.e., the materials forming the sensing units are not selective to any substance in the samples, therefore, it allows the grouping of information into distinct patterns of response, enabling the distinction of complex liquid systems [1]. Aim: Our aim was to use e-tongue system for the assessment the homeopathic medicine Belladonna at different degrees of dilution, in attempt to differentiate highly diluted systems. Methods: Ultrathin films forming the sensing units were prepared by the layer-by-layer technique [4], using conventional polyelectrolytes such as poly(sodium styene sulfonate) (PSS) and poly(allylamine) hydrochloride (PAH), chitosan and poly(3,4-ethylenedioxythiophene) (PEDOT). Homeopathic medicines (Belladonna 1cH, 6cH, 12cH and 30cH) were prepared by dilution and agitation according to Hahnemann´s method [5], using ethanol at 30% (w/w) as vehicle. Experimental data acquisition was conducted by blind tests measurements involving Belladonna samples and the vehicle used in the dilutions. Five independent and consecutive measurements were taken for each solution at 1 kHz, which were further analysed by Principal Component Analysis (PCA), a statistical method largely employed to reduce the dimensionality of the original data without losing information in the correlation of the samples [3]. Results: Figure 1 shows that the five independent measurements are grouped quite closed each other for each solution analysed, with a clear distinction of them. Therefore, it was noticed a change in the observed pattern measured at different days, indicating a reduced reproducibility, although the groups of data could still be identified. Discussion: PCA is a powerful tool highly employed to extract relevant information in the correlation of data analysis of e-tongue systems. PCA plots showed a good statistical correlation of the systems (PC1 + PC2 ³ 90%), with the solutions being straightforwardly distinguished each other and also from the vehicle used. Conclusion: Despite the differences of data obtained along distinct days of analysis, the e-tongue could detect differences among the samples tested, even considering the highly diluted cases studied.

scholarly journals Electronic Tongue Coupled to an Electrochemical Flow Reactor for Emerging Organic Contaminants Real Time Monitoring

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5349 ◽  
Author(s):  
Cátia Magro ◽  
Eduardo P. Mateus ◽  
Juan M. Paz-Garcia ◽  
Susana Sério ◽  
Maria Raposo ◽  
...  
Keyword(s):  
Flow Reactor ◽  
Electronic Tongue ◽  
Principal Component ◽  
Endocrine Disorders ◽  
Secondary Effluent ◽  
Layer By Layer ◽  
Degradation Kinetic ◽  
Methyl Triclosan ◽  
Emerging Organic Contaminants ◽  
By Products

Triclosan, which is a bacteriostatic used in household items, has raised health concerns, because it might lead to antimicrobial resistance and endocrine disorders in organisms. The detection, identification, and monitoring of triclosan and its by-products (methyl triclosan, 2,4-Dichlorophenol and 2,4,6-Trichlorophenol) are a growing need in order to update current water treatments and enable the continuous supervision of the contamination plume. This work presents a customized electronic tongue prototype coupled to an electrochemical flow reactor, which aims to access the monitoring of triclosan and its derivative by-products in a real secondary effluent. An electronic tongue device, based on impedance measurements and polyethylenimine/poly(sodium 4-styrenesulfonate) layer-by-layer and TiO2, ZnO and TiO2/ZnO sputtering thin films, was developed and tested to track analyte degradation and allow for analyte detection and semi-quantification. A degradation pathway trend was observable by means of principal component analysis, being the sample separation, according to sampling time, explained by 77% the total variance in the first two components. A semi-quantitative electronic tongue was attained for triclosan and methyl-triclosan. For 2,4-Dichlorophenol and 2,4,6-Trichlorophenol, the best results were achieved with only a single sensor. Finally, working as multi-analyte quantification devices, the electronic tongues could provide information regarding the degradation kinetic and concentrations ranges in a dynamic removal treatment.

scholarly journals 3D-Printed Graphene Electrodes Applied in an Impedimetric Electronic Tongue for Soil Analysis

Chemosensors ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 50 ◽  
Author(s):  
Americo da Silva ◽  
Braunger ◽  
Neris Coutinho ◽  
Rios do Amaral ◽  
Rodrigues ◽  
...  
Keyword(s):  
Impedance Spectroscopy ◽  
Precision Agriculture ◽  
Soil Analysis ◽  
Electronic Tongue ◽  
Soil Samples ◽  
Electrical Impedance Spectroscopy ◽  
World Population ◽  
Fused Deposition ◽  
Lbl Films ◽  
3D Printed

The increasing world population leads to the growing demand for food production without expanding cultivation areas. In this sense, precision agriculture optimizes the production and input usage by employing sensors to locally monitor plant nutrient within agricultural fields. Here, we have used an electronic tongue sensing device based on impedance spectroscopy to recognize distinct soil samples (sandy and clayey) enriched with macronutrients. The e-tongue setup consisted of an array of four sensing units formed by layer-by-layer (LbL) films deposited onto 3D-printed graphene-based interdigitated electrodes (IDEs). The IDEs were fabricated in 20 min using the fused deposition modeling process and commercial polylactic acid-based graphene filaments. The e-tongue comprised one bare and three IDEs functionalized with poly(diallyldimethylammonium chloride) solution/copper phthalocyanine-3,4′,4′′,4′′′-tetrasulfonic acid tetrasodium salt (PDDA/CuTsPc), PDDA/montmorillonite clay (MMt-K), and PDDA/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) LbL films. Control samples of sandy and clayey soils were enriched with different concentrations of nitrogen (N), phosphorus (P), and potassium (K) macronutrients. Sixteen soil samples were simply diluted in water and measured using electrical impedance spectroscopy, with data analyzed by principal component analysis. All soil samples were easily distinguished without pre-treatment, indicating the suitability of 3D-printed electrodes in e-tongue analysis to distinguish the chemical fertility of soil samples. Our results encourage further investigations into the development of new tools to support precision agriculture.

scholarly journals Multisensor System Based on Layer by Layer Films. Discrimination of Milks

2018 ◽  
Author(s):  
Coral Salvo-Comino ◽  
Celia Garcia-Hernandez ◽  
Cristina Garcia-Cabezon ◽  
Maria Luz Rodriguez-Mendez
Keyword(s):  
Copper Phthalocyanine ◽  
Electronic Tongue ◽  
Principal Component ◽  
Sensor System ◽  
Galactose Oxidase ◽  
Milk Analysis ◽  
Layer By Layer ◽  
Additional Information ◽  
Milk Samples ◽  
On Line

A nanostructured electrochemical bi-sensor system for analysis of milks has been developed using the Layer by Layer technique. The non-enzymatic sensor [CHI+IL/CuPcS]2, is a layered material containing a negative film of the anionic sulfonated copper phthalocyanine (CuPcS) acting as electrocatalytic material, and a cationic layer containing a mixture of an ionic liquid (IL) (1-butyl-3-methylimidazolium tetrafluoroborate) that enhances the conductivity and chitosan (CHI) that facilitates the enzyme immobilization. The biosensor ([CHI+IL/CuPcS]2-GAO) results from the immobilization of galactose oxidase on the top of the LbL layers. FTIR, UV-vis and AFM have confirmed the proposed structure and cyclic voltammetry has demonstrated the amplification caused by the combination of materials in the film. Sensors have been combined to form an electronic tongue for milk analysis. Principal Component Analysis has revealed the ability of the sensor system to discriminate between milk samples with different lactose content. Using PLS-1 calibration models, correlations have been found between the voltammetric signals and chemical parameters measured by classical methods. PLS-1 models provide excellent correlations with lactose content. Additional information about other components such as fats, proteins and acidity can also be obtained. The method developed is simple and the short response time permits its use in assaying milk samples on-line.

scholarly journals Detection of Triclosan in Tuned Solutions by pH and Ionic Strength Using PAH/PAZO Thin Films

Proceedings ◽  
2019 ◽  
Vol 15 (1) ◽  
pp. 25
Author(s):  
Paulo M. Zagalo ◽  
Cátia Magro ◽  
João Pereira-da-Silva ◽  
Benachir Bouchikhi ◽  
Nezha El Bari ◽  
...  
Keyword(s):  
Thin Films ◽  
Ionic Strength ◽  
Sodium Salt ◽  
Personal Care Products ◽  
Electronic Tongue ◽  
Layer By Layer ◽  
Personal Care ◽  
Electrical Parameters ◽  
Adsorbed Amount ◽  
Lbl Films

The electronic tongue concept based on layer-by-layer (LbL) films can be used to the detection in water of triclosan (TCS), a pernicious molecule used in personal care products and widely released in the environment. In this work, we analyzed the adsorption of TCS on poly(allylaminehydrochloride) (PAH) and poly[1-[4-(3-carboxy-4hydroxyphenylazo) benzenesulfonamido]-1,2-ethanediyl, sodium salt] (PAZO) layers of PAH/PAZO LbL films. We demonstrate that the adsorbed amount is strongly dependent of pH, the efficiency of adsorption of TCS on PAH layer is higher, and, when PAZO is the outmost layer, the electrical parameters can discriminate the ionic strength on solutions of TCS.

scholarly journals Triclosan Detection in Aqueous Environmental Matrices by Thin-Films Sensors

Proceedings ◽  
2019 ◽  
Vol 15 (1) ◽  
pp. 24
Author(s):  
Cátia Costa Magro ◽  
Paulo Morgado Zagalo ◽  
João Pereira-da-Silva ◽  
Eduardo Pires Mateus ◽  
Alexandra Branco Ribeiro ◽  
...  
Keyword(s):  
Thin Films ◽  
Deionized Water ◽  
Water Bodies ◽  
Layer By Layer ◽  
Impedance Spectra ◽  
Environmental Matrices ◽  
Interdigitated Electrodes ◽  
Lbl Films ◽  
Aqueous Matrices

Triclosan (TCS), a bacteriostatic detected in water bodies, have inauspicious effects in human and biota. Consequently, there is a critical need of monitoring these type of compounds in aqueous matrices. In this sense, sensors, based on polyethyleneimine and polysodium 4-styrenesulfonate layer-by-layer thin-films adsorbed on supports with gold interdigitated electrodes deposited, were developed. The aim was analyze the sensitivity of discrimination of TCS (10−15 M to 10−5 M) in deionized water, Luso® and in an effluent, by measuring the impedance spectra. LbL films can distinguish TCS concentrations in EF, while in LW was achieved an acceptable sensibility when interdigitated electrodes without films were used.

Recognition of Mineral Water with an Electronic Tongue Based on PCA and PNN

2011 ◽  
Vol 467-469 ◽  
pp. 888-893
Author(s):  
Hong Men ◽  
Yu Ming Guo ◽  
Rui Xia Wen ◽  
Bin Zhu
Keyword(s):  
Neural Network ◽  
Bp Neural Network ◽  
Mineral Water ◽  
Sensor Array ◽  
Probabilistic Neural Network ◽  
Electronic Tongue ◽  
Principal Component ◽  
Original Data ◽  
Accuracy Rate ◽  
Neural Network Algorithm

Electronic Tongue is a kind of intelligent equipment which is used to distinguish tastes. An electronic tongue composed of a sensor array of ion-selective electrodes has been developed and used for the qualitative analysis of five different brands of mineral water. The acquired original data has been optimized by principal component analysis (PCA) and then the probabilistic neural network (PNN) model is designed to process the data. The application results show that the performance of the proposed method has surpasses the traditional BP neural network algorithm, the speed of recognition is fast and the accuracy rate can reach 100%, which gives the electronic tongue system good practicability and feasibility.

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