@article{SiqueiraMakiPaulovichetal.2010, author = {Siqueira, Jose R. and Maki, Rafael M. and Paulovich, Fernando V. and Werner, Frederik and Poghossian, Arshak and Oliveira, Maria C. F. de and Zucolotto, Valtencir and Oliveira, Osvaldo N. Jr. and Sch{\"o}ning, Michael Josef}, title = {Use of information visualization methods eliminating cross talk in multiple sensing units investigated for a light-addressable potentiometric sensor}, series = {Analytical Chemistry}, volume = {82}, journal = {Analytical Chemistry}, number = {1}, publisher = {ACS Publications}, address = {Washington}, issn = {0003-2700}, doi = {10.1021/ac9024076}, pages = {61 -- 65}, year = {2010}, abstract = {The integration of nanostructured films containing biomolecules and silicon-based technologies is a promising direction for reaching miniaturized biosensors that exhibit high sensitivity and selectivity. A challenge, however, is to avoid cross talk among sensing units in an array with multiple sensors located on a small area. In this letter, we describe an array of 16 sensing units of a light-addressable potentiometric sensor (LAPS), which was made with layer-by-layer (LbL) films of a poly(amidomine) dendrimer (PAMAM) and single-walled carbon nanotubes (SWNTs), coated with a layer of the enzyme penicillinase. A visual inspection of the data from constant-current measurements with liquid samples containing distinct concentrations of penicillin, glucose, or a buffer indicated a possible cross talk between units that contained penicillinase and those that did not. With the use of multidimensional data projection techniques, normally employed in information visualization methods, we managed to distinguish the results from the modified LAPS, even in cases where the units were adjacent to each other. Furthermore, the plots generated with the interactive document map (IDMAP) projection technique enabled the distinction of the different concentrations of penicillin, from 5 mmol L-1 down to 0.5 mmol L-1. Data visualization also confirmed the enhanced performance of the sensing units containing carbon nanotubes, consistent with the analysis of results for LAPS sensors. The use of visual analytics, as with projection methods, may be essential to handle a large amount of data generated in multiple sensor arrays to achieve high performance in miniaturized systems}, language = {en} } @article{SiqueiraAbouzarPoghossianetal.2009, author = {Siqueira, Jos{\´e} R. Jr. and Abouzar, Maryam H. and Poghossian, Arshak and Zucolotto, Valtencir and Oliveira, Osvaldo N. Jr. and Sch{\"o}ning, Michael Josef}, title = {Penicillin biosensor based on a capacitive field-effect structure functionalized with a dendrimer/carbon nanotube multilayer}, series = {Biosensors and Bioelectronics. 25 (2009), H. 2}, journal = {Biosensors and Bioelectronics. 25 (2009), H. 2}, isbn = {0956-5663}, pages = {497 -- 501}, year = {2009}, language = {en} } @article{MoraisGomesSilvaetal.2017, author = {Morais, Paulo V. and Gomes, Vanderley F., Jr. and Silva, Anielle C. A. and Dantas, Noelio O. and Sch{\"o}ning, Michael Josef and Siqueira, Jos{\´e} R., Jr.}, title = {Nanofilm of ZnO nanocrystals/carbon nanotubes as biocompatible layer for enzymatic biosensors in capacitive field-effect devices}, series = {Journal of Materials Science}, volume = {52}, journal = {Journal of Materials Science}, number = {20}, publisher = {Springer}, address = {Berlin}, issn = {1573-4803}, doi = {10.1007/s10853-017-1369-y}, pages = {12314 -- 12325}, year = {2017}, abstract = {The incorporation of nanomaterials that are biocompatible with different types of biological compounds has allowed the development of a new generation of biosensors applied especially in the biomedical field. In particular, the integration of film-based nanomaterials employed in field-effect devices can be interesting to develop biosensors with enhanced properties. In this paper, we studied the fabrication of sensitive nanofilms combining ZnO nanocrystals and carbon nanotubes (CNTs), prepared by means of the layer-by-layer (LbL) technique, in a capacitive electrolyte-insulator-semiconductor (EIS) structure for detecting glucose and urea. The ZnO nanocrystals were incorporated in a polymeric matrix of poly(allylamine) hydrochloride (PAH), and arranged with multi-walled CNTs in a LbL PAH-ZnO/CNTs film architecture onto EIS chips. The electrochemical characterizations were performed by capacitance-voltage and constant capacitance measurements, while the morphology of the films was characterized by atomic force microscopy. The enzymes glucose oxidase and urease were immobilized on film's surface for detection of glucose and urea, respectively. In order to obtain glucose and urea biosensors with optimized amount of sensitive films, we investigated the ideal number of bilayers for each detection system. The glucose biosensor showed better sensitivity and output signal for an LbL PAH-ZnO/CNTs nanofilm with 10 bilayers. On the other hand, the urea biosensor presented enhanced properties even for the first bilayer, exhibiting high sensitivity and output signal. The presence of the LbL PAH-ZnO/CNTs films led to biosensors with better sensitivity and enhanced response signal, demonstrating that the adequate use of nanostructured films is feasible for proof-of-concept biosensors with improved properties that may be employed for biomedical applications.}, language = {en} } @article{GasparyanPoghossianVitusevichetal.2011, author = {Gasparyan, Ferdinand V. and Poghossian, Arshak and Vitusevich, Svetlana A. and Petrychuk, Mykhaylo V. and Sydoruk, Viktor A. and Siqueira, Jos{\´e} R. Jr. and Oliveira, Osvaldo N. Jr. and Offenh{\"a}usser, Andreas and Sch{\"o}ning, Michael Josef}, title = {Low-Frequency Noise in Field-Effect Devices Functionalized With Dendrimer/Carbon-Nanotube Multilayers}, series = {IEEE Sensors Journal. 11 (2011), H. 1}, journal = {IEEE Sensors Journal. 11 (2011), H. 1}, publisher = {IEEE}, address = {New York}, isbn = {1530-437X}, pages = {142 -- 149}, year = {2011}, language = {en} } @article{SiqueiraWernerBaeckeretal.2009, author = {Siqueira, Jose R. and Werner, Frederik and B{\"a}cker, Matthias and Poghossian, Arshak and Zucolotto, Valtencir and Oliveira, Osvaldo N. Jr. and Sch{\"o}ning, Michael Josef}, title = {Layer-by-Layer Assembly of Carbon Nanotubes Incorporated in Light-Addressable Potentiometric Sensors}, series = {Journal of Physical Chemistry C. 113 (2009), H. 33}, journal = {Journal of Physical Chemistry C. 113 (2009), H. 33}, publisher = {American Chemical Society}, address = {Washington, DC}, isbn = {1932-7455}, pages = {14765 -- 14770}, year = {2009}, language = {en} } @article{MoraisSilvaDantasetal.2019, author = {Morais, Paulo V. and Silva, Anielle C. A. and Dantas, Noelio O. and Sch{\"o}ning, Michael Josef and Siqueira, Jos{\´e} R., Jr.}, title = {Hybrid Layer-by-Layer Film of Polyelectrolytes-Embedded Catalytic CoFe2O4 Nanocrystals as Sensing Units in Capacitive Electrolyte-Insulator-Semiconductor Devices}, series = {physica status solidi a : applications and materials sciences}, volume = {216}, journal = {physica status solidi a : applications and materials sciences}, number = {1900044}, publisher = {Wiley}, address = {Weinheim}, doi = {10.1002/pssa.201900044}, pages = {1 -- 9}, year = {2019}, language = {en} } @article{SousaSiqueiraVerciketal.2017, author = {Sousa, Marcos A. M. and Siqueira, Jose R. Jr. and Vercik, Andres and Sch{\"o}ning, Michael Josef and Oliveira, Osvaldo N. Jr.}, title = {Determining the optimized layer-by-layer film architecture with dendrimer/carbon nanotubes for field-effect sensors}, series = {IEEE Sensors Journal}, volume = {17}, journal = {IEEE Sensors Journal}, number = {6}, publisher = {IEEE}, address = {New York}, issn = {1558-1748}, doi = {10.1109/JSEN.2017.2653238}, pages = {1735 -- 1740}, year = {2017}, abstract = {The capacitive electrolyte-insulator-semiconductor (EIS) structure is a typical device based on a field-effect sensor platform. With a simple silicon-based structure, EIS have been useful for several sensing applications, especially with incorporation of nanostructured films to modulate the ionic transport and the flat-band potential. In this paper, we report on ion transport and changes in flat-band potential in EIS sensors made with layer-by-layer films containing poly(amidoamine) (PAMAM) dendrimer and single-walled carbon nanotubes (SWNTs) adsorbed on p-Si/SiO 2 /Ta 2 O 5 chips with an Al ohmic contact. The impedance spectra were fitted using an equivalent circuit model, from which we could determine parameters such as the double-layer capacitance. This capacitance decreased with the number of bilayers owing to space charge accumulated at the electrolyte-insulator interface, up to three PAMAM/SWNTs bilayers, after which it stabilized. The charge-transfer resistance was also minimum for three bilayers, thus indicating that this is the ideal architecture for an optimized EIS performance. The understanding of the influence of nanostructures and the fine control of operation parameters pave the way for optimizing the design and performance of new EIS sensors.}, language = {en} } @article{SiqueiraAbouzarBaeckeretal.2009, author = {Siqueira, Jos{\´e} R. Jr. and Abouzar, Maryam H. and B{\"a}cker, Matthias and Zucolotto, Valtencir and Poghossian, Arshak and Oliveira, Osvaldo N. Jr. and Sch{\"o}ning, Michael Josef}, title = {Carbon nanotubes in nanostructured films: Potential application as amperometric and potentiometric field-effect (bio-)chemical sensors}, series = {physica status solidi (a) . 206 (2009), H. 3}, journal = {physica status solidi (a) . 206 (2009), H. 3}, publisher = {Wiley}, address = {Weinheim}, isbn = {1862-6319}, pages = {462 -- 467}, year = {2009}, language = {en} } @article{RodriguesMoraisNordietal.2018, author = {Rodrigues, Raul T. and Morais, Paulo V. and Nordi, Cristina S. F. and Sch{\"o}ning, Michael Josef and Siqueira Jr., Jos{\´e} R. and Caseli, Luciano}, title = {Carbon Nanotubes and Algal Polysaccharides To Enhance the Enzymatic Properties of Urease in Lipid Langmuir-Blodgett Films}, series = {Langmuir}, volume = {34}, journal = {Langmuir}, number = {9}, publisher = {ACS Publications}, address = {Washington, DC}, issn = {1520-5827}, doi = {10.1021/acs.langmuir.7b04317}, pages = {3082 -- 3093}, year = {2018}, abstract = {Algal polysaccharides (extracellular polysaccharides) and carbon nanotubes (CNTs) were adsorbed on dioctadecyldimethylammonium bromide Langmuir monolayers to serve as a matrix for the incorporation of urease. The physicochemical properties of the supramolecular system as a monolayer at the air-water interface were investigated by surface pressure-area isotherms, surface potential-area isotherms, interfacial shear rheology, vibrational spectroscopy, and Brewster angle microscopy. The floating monolayers were transferred to hydrophilic solid supports, quartz, mica, or capacitive electrolyte-insulator-semiconductor (EIS) devices, through the Langmuir-Blodgett (LB) technique, forming mixed films, which were investigated by quartz crystal microbalance, fluorescence spectroscopy, and field emission gun scanning electron microscopy. The enzyme activity was studied with UV-vis spectroscopy, and the feasibility of the thin film as a urea sensor was essayed in an EIS sensor device. The presence of CNT in the enzyme-lipid LB film not only tuned the catalytic activity of urease but also helped to conserve its enzyme activity. Viability as a urease sensor was demonstrated with capacitance-voltage and constant capacitance measurements, exhibiting regular and distinctive output signals over all concentrations used in this work. These results are related to the synergism between the compounds on the active layer, leading to a surface morphology that allowed fast analyte diffusion owing to an adequate molecular accommodation, which also preserved the urease activity. This work demonstrates the feasibility of employing LB films composed of lipids, CNT, algal polysaccharides, and enzymes as EIS devices for biosensing applications.}, language = {en} } @article{AbouzarPoghossianSiqueiraetal.2010, author = {Abouzar, Maryam H. and Poghossian, Arshak and Siqueira, Jos{\´e} R. Jr. and Oliveira, Osvaldo N. Jr. and Moritz, Werner and Sch{\"o}ning, Michael Josef}, title = {Capacitive electrolyte-insulator-semiconductor structures functionalised with a polyelectrolyte/enzyme multilayer: New strategy for enhanced field-effect biosensing}, series = {Physica Status Solidi (A)}, volume = {207}, journal = {Physica Status Solidi (A)}, number = {4}, publisher = {Wiley-VCH}, address = {Berlin}, issn = {1862-6300}, doi = {10.1002/pssa.200983317}, pages = {884 -- 890}, year = {2010}, abstract = {A novel strategy for enhanced field-effect biosensing using capacitive electrolyte-insulator-semiconductor (EIS) structures functionalised with pH-responsive weak polyelectrolyte/enzyme or dendrimer/enzyme multilayers is presented. The feasibility of the proposed approach is exemplarily demonstrated by realising a penicillin biosensor based on a capacitive p-Si-SiO2 EIS structure functionalised with a poly(allylamine hydrochloride) (PAH)/penicillinase and a poly(amidoamine) dendrimer/penicillinase multilayer. The developed sensors response to changes in both the local pH value near the gate surface and the charge of macromolecules induced via enzymatic reaction, resulting in a higher sensitivity. For comparison, an EIS penicillin biosensor with adsorptively immobilised penicillinase has been also studied. The highest penicillin sensitivity of 100 mV/dec has been observed for the EIS sensor functionalised with the PAH/penicillinase multilayer. The lower and upper detection limit was around 20 µM and 10 mM, respectively. In addition, an incorporation of enzymes in a multilayer prepared by layer-by-layer technique provides a larger amount of immobilised enzymes per sensor area, reduces enzyme leaching effects and thus, enhances the biosensor lifetime (the loss of penicillin sensitivity after 2 months was 10-12\%).}, language = {en} }