Search

Controlled on-surface synthesis of polymer films using amide-based, environmentally friendly, nonionic deep eutectic solvents (ni-DESs) has been developed to regulate the porous features of the films. An appropriate combination of acetamide (A), urea (U), and their methyl derivatives (N-methylacetamide (NMA) and N-methylurea (NMU)) was used to prepare ni-DES. Polymer films were electrosynthesized using 4-aminobenzoic acid (4-ABA) and pyrrole as monomers in ni-DESs. We presumed that the flickering-cluster-like complexes and the extended H-bond networks in ni-DESs enhance the porosity of the polymer films, thus improving permeability features, as reflected in sensor performance. Electrosynthesized polymer films, imprinted with biotin templates (MIPs), have been tested as receptors for biotinylated targets. Molecular dynamics simulations of the prepolymerization mixture revealed the formed complexes between 4-ABA and biotin comprising high-frequency H-bonds. X-ray photoelectron spectroscopy (XPS) and reflection absorption infrared spectroscopy (RAIRS) studies revealed the structural integrity in the polymer films irrespective of the medium. Scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) measurements showed a highly corrugated and porous nature for MIPA-U and MIPNMU-U when prepared in A-U and NMU-U ni-DESs. Atomic force microscope (AFM) studies support these observations, displaying an enhancement in the surface roughness from 1.44 nm (MIPaqueous) to 23.6 nm (MIPNMU-U). QCM analysis demonstrated a remarkable improvement in sensitivity of MIPA-U (17.99 +/- 0.72 Hz/mM) and MIPNMU-U (18.40 +/- 0.81 Hz/mM) films toward the biotin methyl ester (BtOMe, biotin derivative) than the MIPaqueous film. The chemosensor devised with the above MIP recognition films selectively recognized BtOMe (LOD = 12.5 ng/mL) and biotinylated biomolecules, as shown by the stability constant K-s values (MIPA-U = 1442 and MIPNMU-U = 1502 M-1). The porous network g

Phage display has become a powerful tool for antibody discovery in a wide variety of fields. This technology allows specific binders for a given antigen to be selected from combinatorial libraries. A key step in the process is characterizing and evaluating antibody clones thus selected to reliably identify the best antigen binders. Novel characterization methods can provide essential insight into the binding mechanism and supplement the information obtained with conventional techniques. In this work, we used a quartz crystal microbalance with dissipation monitoring (QCM-D) to determine the kinetic and thermodynamic binding parameters for phage-displayed VH antibody fragments. Phytohemagglutinin (PHA), a legume lectin of analytical interest, was used as a complex model antigen to select specific VH fragments from a phage-displayed library. Eight VH fragments with a unique amino acid sequence were identified as PHA binders by using the well-established enzyme-linked immunosorbent assay (ELISA). QCM-D measurements, structural analysis and principal component analysis (PCA) were used to evaluate the antibody fragments and identify clone clusters with similar binding characteristics and molecular interaction mechanisms. This unprecedented study has enabled the identification of high-affinity phage-displayed VH antibody fragments for PHA, which could be useful for PHA analysis (apparent association constant ranged from 10e8 to 10e10 1/M). In fact, the proposed methodology provides a useful tool for evaluating and characterizing antibody fragments with capabilities beyond those of conventional techniques., European Regional Development Fund (ERDF), Depto. de Química Analítica, Fac. de Ciencias Químicas, TRUE, pub

Bacterial biofilms are a major cause of harm related to medical infections and biofouling. Thus, 80% of total infections are caused by biofilm-forming microorganisms. Consequently, knowledge of biofilm formation stages is crucial to develop effective treatments to prevent their formation in medical implants, tools, and devices. For this purpose, quartz crystal microbalance (QCM) sensors are becoming a good alternative to analytical methods for the real-time monitoring of bacterial growth in liquid media culture. In a previous paper, the authors described an affordable multi-channel measurement instrument based on QCM sensors. However, in order to validate its correct operation, complementary experimental measurements based on bacterial biofilm growth were performed. In this work, the experimental measurements that allow the identification of the different biofilm formation stages are described. The results obtained are discussed., This research was funded by the Ministry of Science, Innovation of Spain under the project RTI2018-099938-B-I00., Peer Reviewed, Postprint (published version)

We present an in-situ and real-time investigation of the formation of YHO and GdHO thin films grown by reactive e(-)-beam evaporation. Mass changes were continuously monitored during deposition, oxidation, and illumination using a highly sensitive quartz crystal microbalance, while changes in chemical composition and depth profiles were investigated simultaneously by ion beam analysis. Results highlight the strong reactivity of freshly deposited YHx and GdHx films, even under ultra-high vacuum conditions. Oxidation starts at the surfaces of the films and the oxidation rate is strongly dependent on the O-2 pressure. The response of the system under ion beam irradiation and in-situ illumination is also presented and discussed. For the measured mass changes, a quantitative agreement better than 2% was observed between both techniques and demonstrates the consistency and sensitivity of this approach.

The structure and interaction of ionic liquids (ILs) influence their interfacial composition, and their arrangement (i.e., electric double-layer (EDL) structure), can be controlled by an electric field. Here, we employed a quartz crystal microbalance (QCM) to study the electrical response of two non-halogenated phosphonium orthoborate ILs, dissolved in a polar solvent at the interface. The response is influenced by the applied voltage, the structure of the ions, and the solvent polarizability. One IL showed anomalous electro-responsivity, suggesting a self-assembly bilayer structure of the IL cation at the gold interface, which transitions to a typical EDL structure at higher positive potential. Neutron reflectivity (NR) confirmed this interfacial structuring and compositional changes at the electrified gold surface. A cation-dominated self-assembly structure is observed for negative and neutral voltages, which abruptly transitions to an anion-rich interfacial layer at positive voltages. An interphase transition explains the electro-responsive behaviour of self-assembling IL/carrier systems, pertinent for ILs in advanced tribological and electrochemical contexts., QC 20230918

The structure and interaction of ionic liquids (ILs) influence their interfacial composition, and their arrangement (i.e., electric double-layer (EDL) structure), can be controlled by an electric field. Here, we employed a quartz crystal microbalance (QCM) to study the electrical response of two non-halogenated phosphonium orthoborate ILs, dissolved in a polar solvent at the interface. The response is influenced by the applied voltage, the structure of the ions, and the solvent polarizability. One IL showed anomalous electro-responsivity, suggesting a self -assembly bilayer structure of the IL cation at the gold interface, which transitions to a typical EDL structure at higher positive potential. Neutron reflectivity (NR) confirmed this interfacial structuring and compositional changes at the electrified gold surface. A cation-dominated self-assembly structure is observed for negative and neutral voltages, which abruptly transitions to an anion-rich interfacial layer at positive voltages. An interphase transition explains the electro-responsive behaviour of self-assembling IL/carrier systems, pertinent for ILs in advanced tribological and electrochemical contexts.

Rapid and accurate serological analysis of SARS-CoV-2 antibodies is important for assessing immune protection from vaccination or infection of individuals and for projecting virus spread within a population. The quartz crystal microbalance (QCM) is a label-free flow-based sensor platform that offers an opportunity to detect the binding of a fluid-phase ligand to an immobilized target molecule in real time. A QCM-based assay was developed for the detection of SARS-CoV-2 antibody binding and evaluated for assay reproducibility. The assay was cross-compared to the Roche electrochemiluminescence assay (ECLIA) Elecsys (R) Anti-SARS-CoV-2 serology test kit and YHLO's chemiluminescence immunoassay (CLIA). The day-to-day reproducibility of the assay had a correlation of r(2) = 0.99, p < 0.001. The assay linearity was r(2) = 0.96, p < 0.001, for dilution in both serum and buffer. In the cross-comparison analysis of 119 human serum samples, 59 were positive in the Roche, 52 in the YHLO, and 48 in the QCM immunoassay. Despite differences in the detection method and antigen used for antibody capture, there was good coherence between the assays, 80-100% for positive and 96-100% for negative test results. In summation, the QCM-based SARS-CoV-2 IgG immunoassay showed high reproducibility and linearity, along with good coherence with the ELISA-based assays. Still, factors including antibody titer and antigen-binding affinity may differentially affect the various assays' responses.

Background: Exposure to pathogens in public transport systems is a common means of spreading infection, mainly by inhaling aerosol or droplets from infected individuals. Such particles also contaminate surfaces, creating a potential surface-transmission pathway. Methods: A fast acoustic biosensor with an antifouling nano-coating was introduced to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on exposed surfaces in the Prague Public Transport System. Samples were measured directly without pre-treatment. Results with the sensor gave excellent agreement with parallel quantitative reverse-transcription polymerase chain reaction (qRT-PCR) measurements on 482 surface samples taken from actively used trams, buses, metro trains and platforms between 7 and 9 April 2021, in the middle of the lineage Alpha SARS-CoV-2 epidemic wave when 1 in 240 people were COVID-19 positive in Prague. Results: Only ten of the 482 surface swabs produced positive results and none of them contained virus particles capable of replication, indicating that positive samples contained inactive virus particles and/or fragments. Measurements of the rate of decay of SARS-CoV-2 on frequently touched surface materials showed that the virus did not remain viable longer than 1-4 h. The rate of inactivation was the fastest on rubber handrails in metro escalators and the slowest on hard-plastic seats, window glasses and stainless-steel grab rails. As a result of this study, Prague Public Transport Systems revised their cleaning protocols and the lengths of parking times during the pandemic. Conclusions: Our findings suggest that surface transmission played no or negligible role in spreading SARS-CoV-2 in Prague. The results also demonstrate the potential of the new biosensor to serve as a complementary screening tool in epidemic monitoring and prognosis.

Proteinaceous, tunable nanostructures of zein (prolamine of corn) were developed as biotinyl-specific receptors using a molecular imprinting technique. Sacrificial templates, such as latex beads (LB3) and anodized alumina membrane (AAM), have been used to control nanostructural patterns in biotin-imprinted zein (BMZ). Briefly, a methanolic solution of the zein-biotin complex was drop cast upon a self-organized LB3 and AAM templates on Au/quartz surfaces. Subsequent dissolution of these sacrificial templates affords highly oriented, predetermined, and uniformly grown hyperporous (300 nm) and nanowires (150 nm) motifs of zein (BMZ-LB3 and BMZ-AAM), as shown by scanning electron microscopy (SEM). Selective extraction of biotin molecular template cast-off site -selective biotin imprints within these zein nanostructures complementary to biotinyl moieties. Alternatively, biotin-imprinted zein nanoparticles (BMZ-Np) and thin film (BMZ-MeOH) were prepared by coacervation and drop casting methods, respectively. Density functional theoretical (DFT) studies reveal strong hydrogen-bonded interaction of biotin with serine and glutamine residues of zein. Quartz crystal microbalance (QCM) studies show remarkable sensitivity of the hyperporous-BMZ-LB3 and nanowires of BMZ-AAM towards biotin derivative (biotin methyl ester) by five (24.75 +/- 1.34 Hz/mM) and four (18.19 +/- 0.75 Hz/mM) times, respectively, higher than the BMZ-MeOH. Enhanced permeability features of the zein nanostructures, when templated with LB3, enable the QCM detection of biotin-or its derivatives down to 12.9 ng mL-1 from dairy products (Kefir). The outcome of this study shall be a key aspect in interfacing biological materials with micro-/nano-sensors and electronic devices for detecting pertinent analytes using sustainably developed biopolymer-based nanostructures.

The plasma protein histidine-rich glycoprotein (HRG) is implicated in the polarization of macrophages to an M1 antitumoral phenotype. The broadly expressed secreted protein stanniocalcin 2 (STC2), also implicated in tumor inflammation, is an HRG interaction partner. With the aim to biochemically characterize the HRG and STC2 complex, binding of recombinant HRG and STC2 preparations to each other and to cells was explored using the quartz crystal microbalance (QCM) methodology. The functionality of recombinant proteins was tested in a phagocytosis assay, where HRG increased phagocytosis by monocytic U937 cells while STC2 suppressed HRG-induced phagocytosis. The binding of HRG to STC2, measured using QCM, showed an affinity between the proteins in the nanomolar range, and both HRG and STC2 bound individually and in combination to vitamin D3-treated, differentiated U937 monocytes. HRG, but not STC2, also bound to formaldehyde-fixed U937 cells irrespective of their differentiation stage in part through the interaction with heparan sulfate. These data show that HRG and STC2 bind to each other as well as to U937 monocytes with high affinity, supporting the relevance of these interactions in monocyte/macrophage polarity.

A method is presented to directly measure the mass output of an impaction printer coupled with a spark ablation generator. It is based on a quartz crystal microbalance and shown to be reliable in quantifying mass deposition rate. Here, the method is demonstrated with an Au nanoparticle aerosol synthesized under several spark ablation and deposition settings. Changes in the deposition rate in response to changed synthesis conditions follow the spark ablation models on generation rate made in previous studies, validating this novel measurement method. In combination with the volume of a deposit, a good estimate of the film porosity can be made. The Au nanoparticle films synthesized here have a low porosity of 0.18 due to extensive restructuring and compaction on impact with the substrate. The porosity is found to be insensitive to deposition settings and is constant throughout the film. The simplicity and low cost of a quartz crystal microbalance setup make this an accessible method to determine porosity in porous thin films., Electronic Components, Technology and Materials, ChemE/Materials for Energy Conversion and Storage

© 2020 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., [EN] Miniaturized, high-throughput, cost-effective sensing devices are needed to advance lab-on-a-chip technologies for healthcare, security, environmental monitoring, food safety, and research applications. Quartz crystal microbalance with dissipation (QCMD) is a promising technology for the design of such sensing devices, but its applications have been limited, until now, by low throughput and significant costs. In this work, we present the design and characterization of 24-element monolithic QCMD arrays for high-throughput and low-volume sensing applications in liquid. Physical properties such as geometry and roughness, and electrical properties such as resonance frequency, quality factor, spurious mode suppression, and interactions between array elements (crosstalk), are investigated in detail. In particular, we show that the scattering parameter, S 21 , commonly measured experimentally to investigate crosstalk, contains contributions from the parasitic grounding effects associated with the acquisition circuitry. Finite element method simulations do not take grounding effects into account explicitly. However, these effects can be effectively modelled with appropriate equivalent circuit models, providing clear physical interpretation of the different contributions. We show that our array design avoids unwanted interactions between elements and discuss in detail aspects of measuring these interactions that are often-overlooked.

[ES] El presente TFG tiene como objetivo la implementación y puesta en marcha de un sistema de dispensación automática de muestra para aplicaciones de seguridad y calidad alimentaria. El sistema de dispensación de muestra y sistema de fluídica que se pretende implementar se enmarca dentro de las tareas del objetivo 3 del proyecto AGL2016-77702-R ¿Diseño de un biosensor de ADN basado en tecnología HFF-QCM para la detección de sustancias adulterantes en miel¿. Las diferentes tareas que comprenderá el proyecto son las siguientes: (1) Evaluación de los diferentes módulos que forman el sistema de fluídica y el sistema muestreador (autosampler). (2) Uso del software proporcionado por el fabricante para implementar el control de los diferentes bloques que forman que el sistema. Fundamentalmente, la bomba microfluídica de presión, el controlador de presión, las válvulas de selección del medio y de cierre del canal y el autosampler. (3) Implementación de una librería API de control de todo el sistema. Como lenguaje de programación se utilizará preferentemente JAVA Netbeens, aunque se podrían utilizar otros lenguajes como Python o C. (4) Tareas experimentales de testeo consistentes en la inyección de medios líquidos coloreados que permitan una comprobación visual del sistema implementado. El trabajo será codirigido por los profesores Yolanda Jiménez (ETSIT) y Román Fernández (ETSID). Contará también con la directora experimental María Calero., [EN] The objective of this TFG is the implementation and implementation of an automatic sample dispensing system for food safety and quality applications. The sample dispensing system and fluidics system to be implemented is part of the tasks of objective 3 of the AGL2016-77702-R project "Design of a DNA biosensor based on HFF-QCM technology for the detection of adulterating substances in honey". The different tasks to be covered by the project are as follows: (1) Evaluation of the different modules that form the fluidics system and the sampling system (autosampler). (2) Use the software provided by the manufacturer to implement the control of the different blocks that form the system.Essentially, the microfluidic pressure pump, the pressure controller, the medium selection and channel closing valves and the autosampler. (3) Implementation of a system-wide control API library. JAVA Netbeens will preferably be used as a programming language, although other languages such as Python or C could be used. (4) Experimental testing tasks consisting of the injection of colored liquid media that allow a visual check of the implemented system. The work will be co-directed by Professors Yolanda Jiménez (ETSIT) and Román Fernández (ETSID). It will also feature experimental director María Calero.

Measurement of antithyroglobulin antibodies (TgAb) is an inevitable laboratory tool in the management of thyroid gland diseases. Currently available immunoassays still have limitations underlying the necessity of the introduction of fast, sensitive, and label-free technologies. Our aim was to develop a method for TgAb measurement in human serum based on the quartz crystal microbalance (QCM) technology. We immobilized thyroglobulin on the surface of Attana LNB Carboxyl sensor chip®, prepared standard curve covering the range of 1–50000 kIU/L, and established optimal measurement conditions. The validation included determination of the detection limit (LOD), functional sensitivity, linearity, precision, as well as the comparison with the results of the radioimmunoassay (RIA). The LOD and functional sensitivity were 4.2 kIU/L and 4.7 kIU/L, respectively. The method was linear in the range of 20–10000 kIU/L. The regression equation for comparison with RIA was CQCM = 1.0056 • CRIA – 24.2778, whereby no significant proportional or systematic difference was present. There was a good agreement with RIA in the classification of patients according to the clinical significance of the results. The developed method has advantages over currently available assays in terms of better LOQ, a higher upper limit of linearity, and precision. The characteristics of the developed method unambiguously show that the application of the QCM biosensors offers a highly reliable novel approach for the measurement of TgAb in human serum.

The roughness of a surface is known to have a strong influence on the sputtering process. Commonly used 1D Monte Carlo codes for calculating sputter yields show good agreement with experimental data only for comparably flat surfaces, whereas local ion incidence angles, shadowing and redeposition influence the sputter yields in both magnitude and angular dependence on rough surfaces. In the present work, we therefore investigated tungsten samples of largely different roughness, characterised by atomic force and confocal microscopy. A highly sensitive quartz crystal microbalance was used to determine sputter yields during ion irradiation. Low ion fluences were applied to ensure that the surface morphology did not change during irradiation. The results were used to benchmark our new ray-tracing simulation code SPRAY, which can take microscopy images without limitations in size as input. SPRAY was furthermore applied to perform systematic simulations for artificially roughened and computer-generated surfaces. A clear result was that the governing parameter for description of the sputtering behaviour is the mean value of the surface inclination angle distribution, rather than the commonly used root mean square roughness. Our simulations show that this parameter is universally applicable for a wide range of different surface structures.

Metallic films are important in various applications, such as electric devices where it can act as contacts. In electrical devices, the substrate typically consists of silicon dioxide (SiO2) which is a temperature-sensitive substrate. Therefore, plasma enhanced chemical vapor deposition (PECVD) are better suited than thermally activated chemical vapor deposition (CVD). Depositing metallic films with PECVD demands co-reactants that act as reducing agents. However, these are not well-studied and do not always have the power enough to perform the reduction reaction for metals. Recently it has been concluded that electrons can act as reducing agents in the deposition of first row transition metallic films in a PECVD process. By supplying a positive bias to the substrate, the electrons got attracted to the surface of the substrate, which facilitated metal growth. The study concluded that metal growth only occurred at conductive -and semiconductive substrates and that the substrate bias and plasma power affected the metal growth. The process is however not well understood, which causes a knowledge gap, signifying that studies of the surface chemistry are needed. Here a new modified analytical method to study the surface chemistry in the newly developed process mentioned above is presented. The analytical method consists of an electrically modified quartz crystal microbalance (QCM) with gold electrodes as a conductive substrate. This allows the electron current to run through the QCM during the measurement. By supplying a DC-voltage to the front electrode it gets readily biased (negative and positive) and by placing a capacitor in the circuit, it connects the AC-circuit (oscillator circuit) and the DC-circuit (DC-voltage bias circuit). At the same time, it blocks the DC-current from going back to the oscillator but allows the high-frequency signal to pass from the QCM. The results in this thesis concluded that the QCM can be electrically modified to allow an electron flux

The design of biosensors and artificial organs using biocompatible materials with a low affinity for amyloid beta peptide (A beta) would contribute to the inhibition of fibril growth causing Alzheimer's disease. We systematically studied the amyloidogenicity of A beta on various planar membranes. The planar membranes were prepared using biocompatible polymers, viz., poly(methyl methacrylate) (PMMA), polysulfone (PSf), poly(L-lactic acid) (PLLA), and polyvinylpyrrolidone (PVP). Phospholipids from biomembranes, viz., 1,2-dioleoyl-phosphatidylcholine (DOPC), 1,2-dipalmitoyl-phosphatidylcholine (DPPC), and polyethylene glycol-graft-phosphatidyl ethanolamine (PEG-PE) were used as controls. Phospholipid- and polymer-based membranes were prepared to determine the kinetics of A beta fibril formation. Rates of A beta nucleation on the PSf- and DPPC-based membranes were significantly higher than those on the other membranes. A beta accumulation, calculated by the change in frequency of a quartz crystal microbalance (QCM), followed the order: PSf > PLLA > DOPC > PMMA, PVP, DPPC, and PEG-PE. Nucleation rates exhibited a positive correlation with the corresponding accumulation (except for the DPPC-based membrane) and a negative correlation with the molecular weight of the polymers. Strong hydration along the polymer backbone and polymer-A beta entanglement might contribute to the accumulation of A beta and subsequent fibrillation.

Globally, there is growing concern about the health risks of water and air pollution. The U.S. Environmental Protection Agency (EPA) has developed a list of priority pollutants containing 129 different chemical compounds. All of these chemicals are of significant interest due to their serious health and safety issues. Permanent exposure to some concentrations of these chemicals can cause severe and irrecoverable health effects, which can be easily prevented by their early identification. Molecularly imprinted polymers (MIPs) offer great potential for selective adsorption of chemicals from water and air samples. These selective artificial bio(mimetic) receptors are promising candidates for modification of sensors, especially disposable sensors, due to their low-cost, long-term stability, ease of engineering, simplicity of production and their applicability for a wide range of targets. Herein, innovative strategies used to develop MIP-based sensors for EPA priority pollutants will be reviewed.

Molecularly imprinted polymers have emerged as cost-effective and rugged artificial selective sorbents for combination with different sensors. In this study, quaternary ammonium cations, as functional monomers, were systematically evaluated to design imprinted polymers for glyphosate as an important model compound for electrically charged and highly water-soluble chemical compounds. To this aim, a small pool of monomers were used including (3-acrylamidopropyl)trimethylammonium chloride, [2-(acryloyloxy)ethyl]trimethylammonium chloride, and diallyldimethylammonium chloride. The simultaneous interactions between three positively charged monomers and glyphosate were preliminary evaluated using statistical design of the experiment method. Afterwards, different polymers were synthesized at the gold surface of the quartz crystal microbalance sensor using optimized and not optimized glyphosate-monomers ratios. All synthesized polymers were characterized using atomic force microscopy, contact angle, Fourier-transform infrared, and X-ray photoelectron spectroscopy. Evaluated functional monomers showed promise as highly efficient functional monomers, when they are used together and at the optimized ratio, as predicted by the statistical method. Obtained results from the modified sensors were used to develop a simple model describing the binding characteristics at the surface of the different synthesized polymers. This model helps to develop new synthesis strategies for rational design of the highly selective imprinted polymers and to use as a sensing platform for water soluble and polar targets.

Phage display has become a powerful tool for antibody discovery in a wide variety of fields. This technology allows specific binders for a given antigen to be selected from combinatorial libraries. A key step in the process is characterizing and evaluating antibody clones thus selected to reliably identify the best antigen binders. Novel characterization methods can provide essential insight into the binding mechanism and supplement the information obtained with conventional techniques. In this work, we used a quartz crystal microbalance with dissipation monitoring (QCM-D) to determine the kinetic and thermodynamic binding parameters for phage-displayed VH antibody fragments. Phytohemagglutinin (PHA), a legume lectin of analytical interest, was used as a complex model antigen to select specific VH fragments from a phage-displayed library. Eight VH fragments with a unique amino acid sequence were identified as PHA binders by using the well-established enzyme-linked immunosorbent assay (ELISA). QCM-D measurements, structural analysis and principal component analysis (PCA) were used to evaluate the antibody fragments and identify clone clusters with similar binding characteristics and molecular interaction mechanisms. This unprecedented study has enabled the identification of high-affinity phage-displayed VH antibody fragments for PHA, which could be useful for PHA analysis (apparent association constant ranged from 108 to 1010 M−1). In fact, the proposed methodology provides a useful tool for evaluating and characterizing antibody fragments with capabilities beyond those of conventional techniques.

Globally, there is growing concern about the health risks of water and air pollution. The U.S. Environmental Protection Agency (EPA) has developed a list of priority pollutants containing 129 different chemical compounds. All of these chemicals are of significant interest due to their serious health and safety issues. Permanent exposure to some concentrations of these chemicals can cause severe and irrecoverable health effects, which can be easily prevented by their early identification. Molecularly imprinted polymers (MIPs) offer great potential for selective adsorption of chemicals from water and air samples. These selective artificial bio(mimetic) receptors are promising candidates for modification of sensors, especially disposable sensors, due to their low-cost, long-term stability, ease of engineering, simplicity of production and their applicability for a wide range of targets. Herein, innovative strategies used to develop MIP-based sensors for EPA priority pollutants will be reviewed. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

The custom functionalization of a graphene surface allows access to engineered nanomaterials with improved colloidal stability and tailored specific properties, which are available to be employed in a wide range of applications ranging from materials to life science. The high surface area and their intrinsic physical and biological properties make reduced graphene oxide and graphene oxide unique materials for the custom functionalization with bioactive molecules by exploiting different surface chemistries. In this work, preparation (on the gram scale) of reduced graphene oxide and graphene oxide derivatives functionalized with the well-known antibacterial agent salicylic acid is reported. The salicylic acid functionalities offered a stable colloidal dispersion and, in addition, homogeneous absorption on a sample of textile manufacture (i.e., cotton fabrics), as shown by a Raman spectroscopy study, thus providing nanoengineered materials with significant antibacterial activity toward different strains of microorganisms. Surprisingly, graphene surface functionalization also ensured resistance to detergent washing treatments as verified on a model system using the quartz crystal microbalance technique. Therefore, our findings paved the way for the development of antibacterial additives for cotton fabrics in the absence of metal components, thus limiting undesirable side effects.

Bacteria forming biofilms on surgical implants is a problem that might be alleviated by the use of antibacterial coatings. In this article, recombinant spider silk was functionalized with the peptidoglycan degrading endolysin SAL-1 from the staphylococcal bacteriophage SAP-1 and the biofilm-matrix-degrading enzyme Dispersin B from Aggregatibacter actinomycetemcomitans using direct genetic fusion and/or covalent protein–protein fusion catalyzed by Sortase A. Spider silk assembly and enzyme immobilization was monitored using quartz crystal microbalance analysis. Enzyme activity was investigated both with a biochemical assay using cleavage of fluorescent substrate analogues and bacterial assays for biofilm degradation and turbidity reduction. Spider silk coatings functionalized with SAL-1 and Disperin B were found to exhibit bacteriolytic effect and inhibit biofilm formation, respectively. The strategy to immobilize antibacterial enzymes to spider silk presented herein show potential to be used as surface coatings of surgical implants and other medical equipment to avoid bacterial colonization., QC 20200702

Direct detection of whole vegetative bacteria was investigated employing a quartz crystal resonator (QCR) in its nonlinear regime. Escherichia coli (E. coli) in buffer solution under flow was captured on a QCR in a microfluidic cell using a whole-cell anti-E.coli aptamer. The nonlinear distortion in QCR response due to the 'pull' from surface-bound bacteria was measured in realtime as the change in third Fourier harmonic (3f) current and compared with shifts in the traditional acoustic parameters of resonance frequency and dissipation. The change in 3f current showed superior quantitative correlation with E. coli concentrations (105-108 cfu/mL) and at least an order of magnitude better sensitivity than shifts in the traditional acoustic parameters. Most interestingly, underpinned by the strength of bacteria-QCR pull, the nonlinear acoustic principle demonstrated a unique specificity in transduction, even in a mixed sample with another gram-negative bacteria, that can supplement the specificity of the bioreceptors. An analytical expression was derived to quantitatively relate the competing influence of shifts in dissipation and nonlinearity coefficient of the QCR on the change in 3f current. This study demonstrates the potential for reliable direct readout of bioreceptor-mediated binding of whole vegetative bacteria from complex samples using a nonlinear acoustic resonator., QC 20200608

Cell therapy manufacturing is limited by lack of online tools capable of realtime in-process monitoring, particularly of simultaneous changes in multiple orthogonal (mutually independent) parameters. Here, we studied changes in CD36 expression, number density and size (area) of erythroblasts through different stages of erythropoiesis in vitro using a quartz crystal resonator (QCR), integrated with a microscope, and flow cytometry in parallel. An analytical model was developed extending the Kanazawa-Gordon theory. Based on this model, independent correlations were established between changes in each QCR parameter, dissipation (ΔΓ) and resonance frequency (−Δf0), and CD36 expression (from flow cytometry) and cell area (from microscope). The correlation functions were used to derive an acoustic signature (−ΔΓ/Δf0) of the differentiation process that uniquely mapped the relative changes in CD36 expression and late-stage enucleation-related deviations. A method to quantify relative changes in cell area purely from the acoustic parameters was also proposed. This work demonstrated for the first time the potential of an electromechanical tool for online monitoring of concurrently varying orthogonal phenotypic parameters in cell therapy manufacturing. © 2020 The Authors, QC 20210907

I värme- och kraftvärmeverk förbränns olika typer av bränslen för produktion av el och fjärrvärme. Vid förbränningen bildas rökgaser som innehåller föroreningar, till exempel tungmetaller, från bränslet. Anläggningarna har ofta krav på utsläpp både via rökgaserna och avloppsvatten. Rökgaserna renas därmed genom olika tekniker var av en vanlig teknik är rökgaskondensering. Vid rökgaskondenseringen bildas en vätska, kallad rökgaskondensat, som delvis innehåller tungmetaller från bränslet. Rökgaskondensatet måste renas innan det kan lämna anläggningen och det görs bland annat med tungmetalljonbytare. Jonbytarmassan i tungmetalljonbytarkolonnerna behöver bytas ungefär två gånger per driftsäsong då den inte längre kan binda mer tungmetaller. Detta är en kostnad för värme- och kraftvärmeverken som de vill minimera. I denna studie undersöktes om lokal provtagning och analys på ett kraftvärmeverk av ett antal utvalda tungmetaller i rökgaskondensat är en bra metod för att optimering av reningssteget med tungmetalljonbytare. Samt om detta kan säkerställa att miljökraven för tungmetaller i det renade rökgaskondensatet uppfylls. Med optimering avses att jonbytarmassornas fulla kapacitet utnyttjas, d.v.s. att byten av jonbytarmassor kan reduceras utan att riskera otillåtna halter av tungmetaller i de renade rökgaskondensatet till följd av att jonbytarmassorna använts för länge. Även tiden som behöver avsättas för lokal provtagning och analys dokumenterades. I dagsläget sker analyser hos ackrediterade laboratorium där det tar drygt två veckor att få resultatet och under väntetiden kan mycket på anläggningen förändras. En verifiering av resultaten från studien gjordes mot resultat från ett sådant. I denna studie undersöktes lokal provtagning och analys med mätinstrumentet FREEDD som bygger på tekniken kvartskristall mikrobalans (QCM-teknik). Andra alternativ för lokal analys har inte undersökts här. Resultatet visade att det i dagsläget är svårt att med lokal provtagning optimera, In heating and combined heat and power plants, different types of fuels are burned to produce electricity and district heating. During the combustion flue gases containing pollutants, such as heavy metals, are formed from the flue. The plants have requirements for low emissions, both from the flue gases and the wastewater. The flue gases are purified by various techniques and a common technique is flue gas condensation. During the flue gas condensation, a liquid called flue gas condensate, is formed, which partly contains heavy metals from the flue. The flue gas condensate must be cleaned before it can leave the plant. A step in the purification of the flue gas condensate is usually heavy metal ion-exchanger. The ion-exchange mass in the heavy metal ion-exchange columns needs to be changed approximately twice per operating season as it no longer has room to bind more heavy metals. This is an expensive cost for the heating and combined heat and power plants that they want to minimize. This study investigated whether local sampling and analysis at a cogeneration plant of a number selected heavy metals in flue gas condensate is a good method for optimizing the purifications step with heavy metal ion-exchangers. And if this can ensure that the environmental requirements for the heavy metals in the purified flue gas condensate are met. Optimization means that the full capacity of the ion-exchange masses is utilized, i.e. that the exchange of ion-exchange masses can be reduced without risking unauthorized levels of heavy metals in the purified flue gas condensate as a result of the ion exchange masses being used for too long. The time needed for local sampling and analysis was also documented. At present, analyzes are done at accredited laboratories where it takes over two weeks to get the result and during that time much can be changes at the plant. A verification of the result of the study was also made against the result of an accredited laboratory. In this study, loc

Chlorosilane gas transport in ambient hydrogen in a slim vertical cold wall chemical vapor deposition reactor was real-time monitored using a quartz crystal microbalance (QCM) using its behaviour responding to the properties of the gas mixture. The QCM frequency quickly decreased by introducing the trichlorosilane gas, while it slowly decreased by the dichlorosilane gas. The QCM frequency behavior was explained by the gas flow condition, such as the plug flow and recirculating flow, in the reactor. The relationship was consistent with the gas flow calculations, because the heavy and light gases could directly flow downward and recirculate, respectively, in the chamber due to natural convection. The information obtained from the QCM frequency behavior is expected to be utilized for the real-time gas monitoring and for the process design.

Silver nanoparticles (AgNPs) have broad spectrum antibacterial activity, but their toxicity to human cells has raised concerns related to their use as disinfectants or coatings of medically relevant surfaces. To address this issue, NPs comprising intrinsically bactericidal and biocompatible biopolymer and Ag with high antibacterial efficacy against common pathogens and compatibility to human cells have been engineered. However, the reason for their lower toxicity compared to AgNPs has not yet been elucidated. This work studies the in vitro interaction of AgLNPs with model mammalian membranes through two approaches: (i) Langmuir films and (ii) supported planar bilayers studied by quartz crystal microbalance and atomic force spectroscopy. These approaches elucidate the interactions of AgLNPs with the model membranes indicating a prominent effect of the bioresourced lignin to facilitate the binding of AgLNPs to the mammalian membrane, without penetrating through it. This study opens a new avenue for engineering of hybrid antimicrobial biopolymer – Ag or other metal NPs with improved bactericidal effect whereas maintaining good biocompatibility, Peer Reviewed, Postprint (published version)

He-induced nanostructured tungsten (so called W-fuzz) was bombarded with Ar ions under 60 degree and the dynamic erosion behaviour experimentally investigated. By using a highly sensitive quartz-crystal-microbalance technique in a particle catcher configuration the sputtered particles distribution of Wfuzz could be evaluated. In contrast to a at sample, where sputtered particles are emitted primarily in forward direction, we find that W-fuzz samples emit sputtered particles preferably in backward direction (i.e. in the direction of the incident ion beam). After continuous Ar irradiation of a W-fuzz sample the distribution approaches that of a at sample. In addition to experimental data we also show modelling results obtained with a state-of-the-art Monte-Carlo (MC) binary collision approximation (BCA) code TRI3DYN in full 3D. Surface morphology changes as monitored by SEM as well as the dynamic sputtering behaviour can be well reproduced by the full 3D MC-BCA code.

A silicon epitaxial growth process in a trichlorosilane-hydrogen system was evaluated using a quartz crystal microbalance (QCM) placed at the exhaust of a chemical vapor deposition reactor designed for the Minimal Fab. The QCM showed two types of the frequency decrease behaviors, that is, i) a quick shift due to the gas property change caused by the trichlorosilane gas introduction into the ambient hydrogen and ii) the continuous and gradual decrease due to the byproduct deposition on the QCM surface during the silicon epitaxial growth. Because both i) and ii) showed a relationship with the silicon epitaxial growth rate, the in-situ information obtained by the QCM was expected for the real time monitoring of the film deposition process.

Quartz crystal microbalances (QCMs) have been used in the literature for mass sensitive biosensor applications. However, their performance, reliability and stability have been limited by the chemical treatment steps required for the functionalization and activation of the QCM surface, prior to antibody immobilization. Specifically, these steps cause increased film thickness, which diminishes performance by mass overload, and create a harsh environment, which reduces biological activity. In this work, we eliminated this chemical step by introducing a sensing layer modification using electrospun amyloid like-bovine serum albumin (AL-BSA) nanofibers on QCM surfaces. Owing to the self-functionality of AL-BSA nanofibers, these modified QCM surfaces were directly activated by glutaraldehyde (GA). To assess the performance of these modified electrodes, a model protein, lysozyme (Lys), was selected as the biological agent to be immobilized. Frequency measurements were performed in batch (dip-and-dry) and continuous (flow-cell) processes, and binding performances were compared. AL-BSA modified surfaces were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), quartz crystal microbalance (QCM), contact angle (CA) and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). Protein detection was measured based on the frequency shift before and after the covalent bonding of Lys. Under optimized conditions, the proposed immobilization platforms could bind 335 ng/mL and 250 ng/mL of Lys for batch and continuous processes, respectively. Our results demonstrate the potential usage of these self-functional electrospun AL-BSA infrastructure sensing layers on QCM surfaces. This modification enables the direct immobilization of bioactive agents by eliminating any surface functionalization process for further mass-sensitive biosensor applications.

The major aim of this study is to increase the performance of mass sensitive biosensor surfaces by making modifications on quartz crystal microbalance (QCM) surfaces via electrospinning and plasma polymerization techniques. Polyvinyl alcohol (PVA) nanofibers with a diameter of approximately 150 nm were collected on the QCM surfaces by electrospinning technique. Allylamine monomer was used to create specific groups on these nanofiber coated surfaces by plasma polymerization technique. Modified surfaces were characterized by contact angle measurements, scanning electron microscopy, atomic force microscopy, fourier transform infrared spectroscopy and QCM frequency measurements in order to determine the physical and chemical characteristics of the surfaces after each experimental stage. N-H, C-N, C-H and C=O group bands were determined in the IR spectra of the materials. Decrease in the contact angle values of the modified materials indicated the increase in hydrophilicity. Those results showed that amine containing films on the surfaces were successfully deposited using plasma. The performance of modified QCM surfaces was tested via resonance frequency shifts measurements after bovine serum albumin immobilization. In this group of tests, "dip and dry" method and "flow-cell method" were performed and 548 +/- 4 Hz and 50 +/- 5 Hz frequency shifts were obtained respectively. Results of this study revealed that plasma treated electrospun PVA nanofiber modified surfaces can be used for further biosensor applications.

In most bacteria, the early step of septum formation implies the association of soluble FtsZ polymers to the cytoplasmic membrane. ZipA, together with FtsA, provide membrane tethering to FtsZ in Escherichia coli, forming a dynamic proto-ring that serves as an assembly scaffold for the remaining elements of the divisome. Despite their importance for bacterial cell division, multivalent interactions between proto-ring elements at membrane surfaces remain poorly characterized in quantitative terms. Here we measured the binding of FtsZ to ZipA incorporated in supported lipid bilayers at controlled densities by using a combination of biophysical surface-sensitive techniques (quartz crystal microbalance and spectroscopic ellipsometry) and analyzed how ZipA density and FtsZ concentration control the state of assembly of FtsZ. We find that ZipA attachment enables FtsZ-GMPCPP (where GMPCPP is a GTP analogue with reduced hydrolysis) to assemble in several distinct ways, that is: (i) two-dimensional polymerization at the membrane, and (ii) three-dimensional polymerization from the membrane into the solution phase where this may be associated with the formation of higher-order complexes. In these processes, ZipA is required to enrich FtsZ at the surface but the FtsZ bulk concentration defines which morphology is being formed. Moreover, we report a strong effect of the nucleotide (GDP vs GMPCPP/GTP) on the kinetics of ZipA-association/dissociation of FtsZ. These results provide insights on the mode of interaction of proto-ring elements in minimal membrane systems and contribute to complete our understanding of the initial events of bacterial division.

The objective of this thesis was to explore novel approaches for controlling morphologies and molecular recognition behaviour of polymers and to use these strategies in conjunction with the molecular imprinting technique in order to either enhance polymer performance in quartz crystal microbalance (QCM) sensor applications, or as an alternative to conventional solvents of polymerization. In Papers I and II, the use of liquid crystalline media in the synthesis of molecularly imprinted polymers was demonstrated. When used in conjunction with the molecular imprinting technique the LC media induced hierarchical material architectures, which provided an enhancement of QCM-sensor sensitivity. The use of a class of novel solvents, so-called “non-ionic deep eutectic solvents (ni-DESs)”, was explored in polymer synthesis, Paper III, and for molecularly imprinted polymer synthesis, Paper IV. The use of these solvents produced polymers with morphological features comparable to those prepared in conventional solvents, and sensitivities towards bupivacaine template were observed. Collectively these results present a new strategy for generating new hierarchical polymer architectures and a new class of solvent for polymer synthesis, which can also be used for molecular imprinting, that can be used as an alternative to conventional and sometimes flammable or toxic polymerization solvents.

The development of piezoelectric mass-sensitive devices is based on the shift in resonance frequency that is proportional to the deposited mass. However, this holds true only for small, rigid masses, while it can result in mass underestimation for heavy, non-rigid masses. In this work, we demonstrate this 'missing mass' phenomenon by measurement of high molecular weight biomolecules on a Quartz Crystal Microbalance (QCM) platform. For this, we present a model bioassay consisting of a sandwich-type proximity ligation assay for the detection of norovirus-like particles, and its real-time build-up on QCM as an experimental evidence. Upon combination with a localized QCM platform, we explain the pronounced slipping effect in multilayer biological systems resulting in energy dissipation and subsequent mass underestimation. This helps in pointing out the limitations of mega-gravity field sensors for molecular diagnostics where absolute quantification of pathogen load becomes indispensable towards biosensing applications.

Vaccines are produced from antigenic subunits, such as proteins, which are poorly immunogenic, i.e. they fail to trigger a sufficient immune response and a memory effect, especially in children. The immunostimulation capacity of most vaccines is enhanced thanks to vaccine adjuvants, among which aluminum hydroxide (AH) is the most widely used. Antigen adsorption on AH adjuvant particles has been identified as an important step to produce effective vaccines. Controlling antigen-AH interactions is thus a key challenge in vaccine formulation. The aim of this work was to develop a new platform, based on quartz crystal microbalance (QCM), to monitor directly and in real time the adsorption of proteins, taken as model antigens, on adjuvant particles. The addressed challenges were (i) to assemble AH particles at the surface of QCM sensors into thin, continuous and stable layers, and (ii) to use these AH-modified sensors for the measurement of protein adsorption in different pH and ionic strength conditions, with a view to unravel adsorption mechanisms. The modified sensors were successfully elaborated with two different commercial AH adjuvants. The immobilized AH particle layers were thin (20-80 nm thick), stable under different pH and saline conditions, and reached a high surface coverage on the QCM sensors. The adsorption results revealed that bovine serum albumin (BSA) adsorption was not exclusively driven by electrostatic interactions at physiological pH. Moreover, the role of PO4-OH ligand exchanges was highlighted in the adsorption of ovalbumin, as well as in BSA adsorption, despite the fact that the latter has a low phosphate content. The two different AH adjuvants behaved differently towards protein adsorption, even though their physicochemical properties were similar. The immobilization of adjuvant particles on QCM sensors offers a new platform for the study of antigen adsorption, to the benefit of vaccine formulation, and also enriches the range of applications fo, (AGRO - Sciences agronomiques et ingénierie biologique) -- UCL, 2018

The use of liquid crystalline (LC) media as sacrificial templates during the polymer synthesis has been explored. The LC-media introduce morphological features into resultant polymers which when used together with molecular imprinting can produce materials with hierarchical architectures. Bupivacaine (1) imprinted co-polymers of 2-hydroxyethylmethacrylate (HEMA) (2a) and 1,4-divinylbenzene (DVB) (3a) were synthesized using photochemical initiation in lyotrophic liquid crystalline phases of AOT (5) in water/p-xylene and Triton X-100 (6) /water systems. SEM studies revealed the impact of the LC-media on polymer morphology, with polymer brush-like structures, with bristles of ≈30 nm diameter. The polymer morphology reflects that of the hexagonal phase of the LC medium. The rebinding characteristics of polymer films were evaluated quartz crystal microbalance (QCM, under FIA conditions). The influence of the presence of imprinting-derived recognition sites in AOT (5) in water/p-xylene polymer film induced brush-like features which provided a 25-fold enhancement of sensor sensitivity. This chemosensor was shown to be selective for the local anesthetic template, bupivacaine, through studies using the structural analogues ropivacaine and mepivacaine.

A chemosensor utilizing electro-polymerized film, as recognition element, has been devised and tested for selective determination of aspirin. The sensor consists of molecularly imprinted polymer (MIP) recognition elements electrodeposited as polymeric nanowires on gold-coated quartz resonator. A nano structures were prepared by electrochemical co-polymerization of the preformed complex between the template, aspirin, the functional monomers, 3-thienylboronic acid (3-TBA) and 3-thiopheneacetic acid (3-TAA), and thiophene, which was employed as a cross-linker. This nanostructure upon leaching aspirin serve as MIP. Polymerizations were performed in acetonitrile (MIP-org) as well as a micelle forming medium (MIP-mic). For MIP nanowire (MIP-ano) synthesis, sacrificial alumina templates were used during electro-polymerization in acetonitrile. Scanning electron microscope studies revealed compactly arranged polythiophene nanowires of uniform thickness in MIP-ano film, and MIP-mic film produced aggregated micron sized polymer structures. Density functional theoretical studies indicated a stable hydrogen bond-based complexation of aspirin by 3-TBA and 3-TAA in the pre-polymerization mixture implying that the MIP film thus prepared could selectively rebind the aspirin template. The MIP-ano-based chemosensor was sensitive towards aspirin (0.5-10 mM), over clinically relevant range (0.15-0.5 mM) under optimized FIA conditions. The sensitivity (20.62 Hz/mM) of the MIP-ano was eight and fifteen times higher than the MIP-mic (2.80 Hz/mM) and MIP-org (1.10 Hz/mM). Notably, the sensor selectively discriminates aspirin from structurally or functionally related interferants and metabolites, such as, salicylic acid, acetylsalicyloyl chloride and ibuprofen.

The role of sulfur in glycosidic bonds has been evaluated using quartz crystal microbalance methodology. Synthetic routes towards alpha 1-2- and alpha 1-6-linked dimannosides with S-or O-glycosidic bonds have been developed, and the recognition properties assessed in competition binding assays with the cognate lectin concanavalin A. Mannose-presenting QCM sensors were produced using photoinitiated, nitrenemediated immobilization methods, and the subsequent binding study was performed in an automated flow-through instrumentation, and correlated with data from isothermal titration calorimetry. The recorded Kd-values corresponded well with reported binding affinities for the O-linked dimannosides with affinities for the alpha 1-2-linked dimannosides in the lower micromolar range. The S-linked analogs showed slightly disparate effects, where the alpha 1-6-linked analog showed weaker affinity than the O-linked dimannoside, as well as positive apparent cooperativity, whereas the alpha 1-2-analog displayed very similar binding compared to the O-linked structure., QC 20171121

In the adaptation to the oxidative environment on earth, metals played a crucial role for the evolution of life. The presence of metals also allowed access to advanced functions due to their unique coordination sphere and reactivity. This thesis focused on exploiting these unique properties for further development of the field of dynamic chemistry – a field in which adaptation plays a central role as well. The first part of the thesis aimed to create a better understanding of multivalent effects in carbohydrate-lectin interactions. By reversible ligand coordination to zinc ions one of the nanoplatforms, the Borromean rings, could be selectively obtained. After carbohydrate functionalization the binding events were monitored by quartz crystal microbalance technology and compared to glycosylated fullerenes and dodecaamide cages. Overall, this investigation indicated that statistical and polyelectrolyte effects play a considerable role in the observed multivalent effects. The second part of the thesis aimed to design and synthesize a new catalyst for application in aqueous olefin metathesis. This afforded a ruthenium based catalyst that was applied in the self- and cross-metathesis of highly functionalized substrates, such as carbohydrates. In addition, it was shown that addition of a small amount of acetic acid prevented undesired double bond isomerization. The last part of the thesis aimed to explore new methods to discover transition metal catalysts. Dynamic exchange of directing groups generated a pool of potential substrates for C-H activation. Combining this pool of substrates with a pool of potential catalysts resulted in amplification of a reactive substrate/metal combination. By iterative deconvolution in combination with mass spectrometry, this “intermediate” could be identified from the mixture, proving applicability of this alternative approach to catalyst discovery., QC 20170809

Monitoring pluripotent stem cell behaviors (self-renewal and differentiation to specific lineages/phenotypes) is critical for a fundamental understanding of stem cell biology and their translational applications. In this study, a multi-modal stem cell monitoring system was developed to quantitatively characterize physico-electrochemical changes of the cells in real time, in relation to cellular activities during self-renewal or lineage-specific differentiation, in a non-destructive, label-free manner. The system was validated by measuring physical (mass) and electrochemical (impedance) changes in human induced pluripotent stem cells undergoing self-renewal, or subjected to mesendodermal or ectodermal differentiation, and correlating them to morphological (size, shape) and biochemical changes (gene/protein expression). An equivalent circuit model was used to further dissect the electrochemical (resistive and capacitive) contributions of distinctive cellular features. Overall, the combination of the physico-electrochemical measurements and electrical circuit modeling collectively offers a means to longitudinally quantify the states of stem cell self-renewal and differentiation.

In a natural geochemical cycle, manganese-oxide minerals (MnOx ) are principally formed through a microbial process, where a putative multicopper oxidase MnxG plays an essential role. Recent success in isolating the approximately 230 kDa, enzymatically active MnxEFG protein complex, has advanced our understanding of biogenic MnOx mineralization. Here, the kinetics of MnOx formation catalyzed by MnxEFG are examined using a quartz crystal microbalance (QCM), and the first electrochemical characterization of the MnxEFG complex is reported using Fourier transformed alternating current voltammetry. The voltammetric studies undertaken using near-neutral solutions (pH 7.8) establish the apparent reversible potentials for the Type 2 Cu sites in MnxEFG immobilized on a carboxy-terminated monolayer to be in the range 0.36-0.40 V versus a normal hydrogen electrode. Oxidative priming of the MnxEFG protein complex substantially enhances the enzymatic activity, as found by in situ electrochemical QCM analysis. The biogeochemical significance of this enzyme is clear, although the role of an oxidative priming of catalytic activity might be either an evolutionary advantage or an ancient relic of primordial existence.

[EN] An autoantigen piezoelectric sensor to quantify specific circulating autoantibodies in human serum is developed. The sensor consisted on a quartz crystal microbalance with dissipation monitoring (QCM-D) where TRIM21 and TROVE2 autoantigens were covalently immobilized, allowing the selective determination of autoantibodies for diagnosis and prognosis of Systemic Lupus Erythematosus (SLE). The sensitivity of the biosensor, measured as IC50 value, was 1.51 U/mL and 0.32 U/mL, for anti-TRIM21 and anti-TROVE2 circulating autoantibodies, respectively. The sensor is also able to establish a structural interaction fingerprint pattern or profile of circulating autoantibodies, what allows scoring accurately SLE patients. Furthermore, a statistical association of global disease activity with TRIM21-TROVE2 interaction was found (n=130 lupic patient samples, p-value=0.0413). The performances of the biosensor were compared with standard ELISA and multiplex DVD-array high-throughput screening assays, corroborating the viability of piezoelectric biosensor as a cost-effective in vitro assay for the early detection, monitoring or treatment of rare diseases.