Categoría publications

Publication on AWSensors technology

High Fundamental Frequency (HFF) Monolithic Quartz Crystal Microbalance with Dissipation Array for the Simultaneous Detection of Pesticides and Antibiotics in Complex Food

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Authors: María Calero, Román Fernández, María García, Marisol Juan-Borrás, Isabel Escriche, Antonio Arnau, Ángel Montoya and Yolanda Jiménez.

Journal: Biosensors (2022)

 

Abstract

As in the case of the food industry in general, there is a global concern about safety and quality in complex food matrices, such as honey, which is driving the demand for fast, sensitive and affordable analytical techniques across the honey-packaging industry. Although excellent techniques such as liquid chromatography-tandem mass spectrometry (LC-MS/MS) are available, these are located in centralized laboratories and are still lacking in speed, simplicity and cost-effectiveness. Here, a new approach is presented where a competitive immunoassay is combined with a novel High Fundamental Frequency Quartz Crystal Microbalance with Dissipation (HFF-QCMD) array biosensor for the simultaneous detection of antibiotics and pesticides in honey. Concretely, thiabendazole and sulfathiazole residues were monitored in spiked honey samples. Results revealed that HFF-QCMD arrays provide a complementary and reliable tool to LC-MS/MS for the analysis of contaminants in these kinds of complex matrices, while avoiding elaborate sample pre-treatment. The good sensitivity achieved (I50 values in the 70–720 µg/kg range) and the short analysis time (60 min for 24 individual assays), together with the ability for multiple analyte detection (24 sensor array) and its cost-effectiveness, pave the way for the implementation of a fast on-line, in situ routine control of potentially hazardous chemical residues in honey.

QCMD array cartridge microfluidics

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Publication on AWSensors technology

Membrane insertion mechanism of the caveola coat protein Cavin1

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Authors: Liu, K.-C., Pace, H., Larsson, E., Hossain, S., Kabedev, A., Shukla, A., Jerschabek, V., Mohan, J., Bergström, C. A. S., Bally, M., Schwieger, C., Hubert, M., & Lundmark, R.

Journal: PNAS (2022)

 

Abstract

Caveolae are small plasma membrane invaginations, important for control of membrane tension, signaling cascades, and lipid sorting. The caveola coat protein Cavin1 is essential for shaping such high curvature membrane structures. Yet, a mechanistic understanding of how Cavin1 assembles at the membrane interface is lacking. Here, we used model membranes combined with biophysical dissection and computational modeling to show that Cavin1 inserts into membranes. We establish that initial phosphatidylinositol (4, 5) bisphosphate [PI(4,5)P2]–dependent membrane adsorption of the trimeric helical region 1 (HR1) of Cavin1 mediates the subsequent partial separation and membrane insertion of the individual helices. Insertion kinetics of HR1 is further enhanced by the presence of flanking negatively charged disordered regions, which was found important for the coassembly of Cavin1 with Caveolin1 in living cells. We propose that this intricate mechanism potentiates membrane curvature generation and facilitates dynamic rounds of assembly and disassembly of Cavin1 at the membrane.

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Scientific publication

The effects of local graphitization on the charging mechanisms of microporous carbon supercapacitor electrodes

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Authors: Huan Yin, Hui Shao, Barbara Daffos, Pierre-Louis Taberna, Patrice Simon.
Journal: Electrochemistry Communications (2022)

 

Abstract

The electrochemical quartz crystal microbalance (EQCM) technique has been used to study the charge mechanisms in two TiC-derived nanoporous carbons (CDC), synthesized at 800℃ and 1100℃. These two carbons have a similar pore size and porous volume, but the CDC prepared at 1100°C shows a more graphitic microstructure. The EQCM study revealed that the charge storage mechanism in the CDC-800 is mainly controlled by a counter-ion adsorption process, while an expanded ion-exchange process was observed for the CDC-1100. Combined with the potential of zero charge (PZC), these measurements suggest a strong interaction between the anions and graphitic carbon. For the first time, we provide experimental evidence that the local carbon structure affects the charge storage mechanism of the electrical double-layer capacitance in high surface area porous carbons.

graphitization graphical abstract

 

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Scientific publication

Electropolymerization of thiazole derivatives bearing thiophene and selenophene and the potential application in capacitors

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Authors: Seongjun Hong, Joon Ho Yoon, Seunghyun Jeong, Yang-Rae Kim and In Tae Kim.
Journal: Journal of Electroanalytical Chemistry (2022)

 

Abstract

Three thiazole derivatives bearing thiophene and selenophene are synthesized and used as monomers for electropolymerization. The electropolymerization process is studied using cyclic voltammetry (CV) and electrochemical quartz crystal microbalance (EQCM) techniques. Deep understanding is obtained regarding the pseudocapacitor performance of deposited polymer layers by subjecting the macroelectrode and ultramicroelectrode to CV and galvanostatic charging–discharging experiments in three kinds of electrolytes. Notably, the highest specific capacitance is observed in the derivative bearing selenopheno[3,4-d]thiazole and selenophene in a solution of tetrabutylammonium tetrafluoroborate. Furthermore, the electropolymerization rate is influenced by the kind of chalcogenophene and the CV scan rate. A spectroelectrochemistry experiment reveals the optical and electrochromic behavior of the deposited polymer layers. From these results, the pseudocapacitor performance of the deposited polymer layers is related to anion intercalation/deintercalation processes by faradaic reactions of oligomer chains. The EQCM experiments also reveal these processes during electropolymerization and anion intercalation/deintercalation into the deposited polymer layers. Finally, the approximate molecular weight of the solvated anion and the number of solvent molecules surrounding a solvated anion are analyzed using the EQCM data.

 

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Scientific publication

High Frequency (100, 150 MHz) Quartz Crystal Microbalance (QCM) Piezoelectric Genosensor for the Determination of the Escherichia coli O157 rfbE Gene

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Authors: Kaory Barrientos, María Isabel Rocha, Marisol Jaramillo and Neil Aldrín Vásquez.
Journal: Analytical Letters (2022)

 

Abstract

Escherichia coli O157 (E. coli O157) is responsible for outbreaks of high morbidity in food-borne infections. The development of sensitive, reliable, and selective detection systems is of great importance in food safety. In this work, two high fundamental frequency (HFF) piezoelectric genosensors (100 and 150 MHz) were designed and validated for the rfbE gene detection, which encodes O-antigen in E. coli O157. HFF resonators offer improved sensitivity, small sample volumes, and the possibility of integration into lab-on-a-chip devices, but their sensing capabilities have not yet been fully explored. This HFF-QCM genosensor uses the method of physisorption based on the union between the streptavidin and the biotin to immobilize the genetic bioreceptor on the surface and detect its hybridization with the target sequence. Parameters such as molecular coating, specificity, and variability were tested to enhance its performance. Although both genosensors evaluated are able to determine the target, the 100 MHz device has a higher response to the analyte than the 150 MHz platform. This is the first step in the development of an HFF-QCM genosensor that may be used as a trial test of E. coli O157 in large batches of samples.

 

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Publication on AWSensors technology

Interfacial charge storage mechanisms of composite electrodes based on poly(ortho-phenylenediamine)/carbon nanotubes via advanced electrogravimetry

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Authors: El Mahdi Halim, Rezan Demir-Cakan, Hubert Perrot, Mama El Rhazi, Ozlem Sel

Journal: The Journal of Chemical Physics (2022)

 

Abstract

To reach a deeper understanding of the charge storage mechanisms of electrode materials is one of the challenges toward improving their energy storage performance. Herein, we investigate the interfacial ion exchange of a composite electrode made of carbon nanotube/poly( ortho-phenylenediamine) (CNT/P oPD) in a 1M NaCl aqueous electrolyte via advanced electrogravimetric analyses based on electrochemical quartz crystal microbalance (EQCM). Classical EQCM at different scan rates of the potential revealed the complex electrogravimetric behavior likely due to multi-species participation at different temporal scales. Thereafter, in order to better understand the behavior of each species (ions, counter ions, and co-ions) in the charge compensation mechanism, the electrogravimetric impedance spectroscopy analysis (also called ac-electrogravimetry) was pursued. Ac-electrogravimetry revealed the role of each species where Na + cations and Cl − anions as well as protons participate in the charge compensation mechanism of the CNT/P oPD composite with different kinetics and proportions. The water molecules with opposite flux direction with the cations are also detected, suggesting their exclusion during cationic species transfer. Having analyzed ac-electrogravimetry responses in depth, the synergistic interaction between the CNT and P oPD is highlighted, revealing the improved accessibility of species to new sites in the composite.

 

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Scientific publication

Interface evolution and performance degradation in LiCoO2 composite battery electrodes monitored by advanced EQCM

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Authors: Wanli Gao, Christel Laberty-Robert, Natacha Krins, Catherine Debiemme-Chouvya, Hubert Perrot and Ozlem Sel.
Journal: Electrochimica Acta (2022)

 

Abstract

Unravelling the underlying reasons for degradation mechanism of battery materials is of great fundamental and practical importance. For a classical electrode consisting of an active material, a conductive additive, and a polymeric binder, its capacity fading is commonly related with (i) mechanical degradation of polymeric binder and/or (ii) structural and compositional degradation of active materials. The former is more relevant for electrodes showing volume expansion and represented by the progressive breakage of polymeric binder network during battery operation, leading to the dissolution of the other two components into electrolytes. The latter is generally reflected by an irreversible phase transition in active materials, which may affect the species exchanged at the electrode/electrolyte interface and their interfacial transfer dynamics. By employing a coupled methodology pairing electrochemical techniques with piezoelectric probes derived from quartz crystal microbalance (QCM), this work reports on the evolution of the interfacial processes during electrochemical cycling and correlates to the performance degradation of the electrodes. Shown on a LiCoO2 (LCO) composite electrode as a model system, it was revealed that bare Li+ without a hydration sheath plays a dominant role in charge balance irrespective of the aging degree of the electrode under the experimental conditions of this work. However, Li+ transfer is closely accompanied with free H2O molecules with a Li+:H2O ratio around 10:1 at a polarization state close to LCO redox potential (0.65 V vs. Ag/AgCl). This ratio persists in all cycled electrodes with gradually faded interfacial transfer kinetics of Li+ and H2O along cycling. Such a fading in species interfacial transfer kinetics driven by the surficial evolution from LiCoO2 to CoO plays a major role in the electrode performance degradation during cycling.

LiCoO2 composite battery electrodes

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Scientific publication

Ion Dynamics at the Carbon Electrode/Electrolyte Interface: Influence of Carbon Nanotubes Types

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Authors: Freddy Escobar-Teran, Hubert Perrot and Ozlem Sel.
Journal: Materials (2022)

 

Abstract

Electrochemical quartz crystal microbalance (EQCM) and AC-electrogravimetry methods were employed to study ion dynamics in carbon nanotube base electrodes in NaCl aqueous electrolyte. Two types of carbon nanotubes, Double Wall Carbon Nanotube (DWCNT) and Multi Wall Carbon Nanotube (MWCNT), were chosen due to their variable morphology of pores and structure properties. The effect of pore morphology/structure on the capacitive charge storage mechanisms demonstrated that DWCNT base electrodes are the best candidates for energy storage applications in terms of current variation and specific surface area. Furthermore, the mass change obtained via EQCM showed that DWCNT films is 1.5 times greater than MWCNT films in the same potential range. In this way, the permselectivity of DWCNT films showed cation exchange preference at cathode potentials while MWCNT films showed anion exchange preference at anode potentials. The relative concentration obtained from AC-electrogravimetry confirm that DWCNT base electrodes are the best candidates for charge storage capacity electrodes, since they can accommodate higher concentration of charged species than MWCNT base electrodes.

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Scientific publication

Synthesis and covalent immobilization of redox-active metallopolymers for organic phase electrochemistry

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Authors: Hanna Hübner, Riccardo Candeago, Deborah Schmitt, Alexander Schießer, Beichen Xiong, Markus Gallei and Xiao Su.
Journal: Polymer (2022) 244, 124656.

 

Abstract

Redox-active metallopolymers are promising stimuli-responsive platforms for a range of applications including sensing, energy storage, and selective separations. In particular, heterogeneously-functionalized metallopolymers can modulate the capture and release of target molecules, driven by redox electron-transfer. However, prior metallopolymer-functionalized electrodes have been fabricated by non-covalent methods, and tailored for aqueous phase applications. As such, despite the existing potential for heterogeneous applications in organic phase, there are significant constraints to the stability of metallopolymers in organic solvents, including high solubility in solvents such as chloroform or tetrahydrofuran. We propose the immobilization of thiol-functionalized redox-active metallopolymers on metallic surfaces as a facile way to enhance stability and cyclability in organic media, and thus broaden the applicability of redox-metallopolymers for organic phase applications. We explore the anionic polymerization of metal-containing monomers vinylferrocene (VFc) and ferrocenyldimethylsilane (FS), and their thiol end-functionalization by living anionic polymerization strategies. PFS and PVFc with molar masses ranging from 1800 to 49900 g mol−1 and 2900 to 6300 g mol−1 respectively were prepared with a segment of poly(ethylene sulfide), as characterized by size-exclusion chromatography, NMR spectroscopy, MALDI/ToF, thermogravimetry, and elemental analysis. Both metallopolymers were immobilized on gold substrates by a grafting-to protocol, with demonstrated redox-responsiveness by electrochemical control. In the case of immobilized PVFc, operando electrochemical testing demonstrated the stable and reversible electrochemical cycling capabilities (>74% maximum current retained after 100 oxidation/reduction cycles) in several organic solvents including chloroform, tetrahydrofuran, ethanol, methanol, acetonitrile, and acetone. Immobilized PFS was stable in chloroform, with a 83% maximum current retained after 100 oxidation/reduction cycles. We envision future applications of these covalently immobilized metallopolymers for a broad range of fields from selective separations to sensing and energy storage.

 

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Publication on AWSensors technology

Adsorption of organic matter on titanium surfaces with nano- and micro-scale roughness studied with the electrochemical quartz crystal microbalance dissipation technique

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Authors: Claes-Olof A. Olsson, Anna Neus Igual-Muñoz, and Stefano Mischler.

Journal: Biointerphases 2021.

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