This work reports the innovative combination of a molecularly-imprinted polymer (MIP) and a natural antibody for the accurate surface-enhanced Raman spectroscopy (SERS) detection of carcinoembryonic ...antigen (CEA). The MIP material acted as a pre-concentration scheme for the target protein, while the natural antibody was responsible to signal the presence of CEA on the MIP platform.
Gold-based screen-printed electrodes were used as substrate and gallic acid (GA) was used herein for the first time in the assembly of a MIP film, by electropolymerization, in the presence of CEA. This layer was further covered by a second ultra-thin film of electropolymerized benzoic acid (BA), to avoid non-specific binding. The rebinding features of the MIP film were evaluated by electrochemical impedance spectroscopy (EIS) and a linear response was observed from 1 to 1000 ng/mL.
For a sensitive SERS detection, the MIP film was first incubated in sample containing CEA and next incubated in SERS tag. For the SERS tag, gold nanostars (AuNSs) were employed as metal support, coupled to 4-aminothiophenol (4-ATP) as Raman reporter and to a natural antibody for CEA as recognition element. The overall system showed a sensitive response down to 1.0 ng/mL, which was different from the blank signal.
Overall, the innovative approach presented herein combines the advantages of using two different targeting elements for CEA. The costs and time of MIP production were substantially low due to selection of electropolymerization approach and the proposal described herein may be extended to other target molecules.
•Combining Molecularly-imprinted polymer (MIP) with antibodies in SERS analysis.•MIP produced by electropolymerizing gallic acid on screen-printed electrodes.•MIP material used as a pre-concentrating agent of CEA, the target protein.•Raman tag assembled with anti-CEA and a suitable reporter on gold-nanostars.•Detecting CEA by direct electrochemistry and by SERS.
This work describes an electrochemical sensor with a biomimetic plastic antibody film for carcinoembryonic antigen (CEA, an important biomarker in colorectal cancer), integrated in the electrical ...circuit of a direct methanol fuel cell (DMFC), working in passive mode and used herein as power supply and signal transducer. In detail, the sensing layer for CEA consisted of a Fluorine-doped Tin Oxide (FTO) conductive glass substrate – connected to the negative pole side of the DMFC – with a conductive poly (3,4-ethylenedioxythiophene) (PEDOT) layer and a polypyrrol (PPy) molecularly-imprinted polymer (MIP), assembled in-situ. This sensing element is then closed using a cover FTO-glass, hold in place with a clip, connected to the positive side of the DMFC. When compared with control DMFCs, the power curves of DMFC/Sensor integrated system showed decreased power values due to the MIP layer interfaced in the electrical circuit, also displaying high stability signals. The DMFC/Sensor was further calibrated at room temperature, in different medium (buffer, a synthetic physiological fluid model and Cormay® serum), showing linear responses over a wide concentration range, with a limit of detection of 0.08 ng/mL. The DMFC/Sensor presented sensitive data, with linear responses from 0.1 ng/mL to 100 μg/mL and operating well in the presence of human serum.
Overall, the results obtained evidenced the possibility of using a DMFC as a transducing element in an electrochemical sensor, confirming the sensitive and selective readings of the bio (sensing) imprinted film. This integration paves the way towards fully autonomous electrochemical devices, in which the integration of the sensor inside the fuel cell may be a subsequent direction.
•Passive methanol fuel cell and electrochemical biosensor integrated for the first time.•Molecularly-imprinted polymer generated in situ for carcinoembryonic antigen detection.•Two-electrode configuration electrochemical cell as the biosensor.•Power of the fuel cell is carcinoembryonic antigen concentration dependent.•The use of passive methanol fuel cell allows point-of-care applications.
Bisphenols A (BPA) and S (BPS) are endocrine-disrupting chemicals that affect energy metabolism, leading to impairment of glucose and lipid homeostasis. We aimed at identifying metabolic pathways ...regulated by both compounds in human liver cells and rat pancreatic β-cells that could impair energy homeostasis regulation. We assessed the effects on growth, proliferation, and viability of hepatocarcinoma (HepG2) and insulinoma (INS-1E) cells exposed to either BPA or BPS in a full range concentration between 0.001 and 100 μM. Both the dose and duration of exposure caused a differential response on growth and viability of both cells. Effects were more pronounced on HepG2, as these cells exhibited non-linear dose-responses following exposure to xenobiotics. For INS-1E, effect was observed only at the highest concentration. In addition, we profiled their intracellular state by untargeted metabolomics at 24, 48, and 72 h of exposure. This analysis revealed time- and dose-dependently molecular changes for HepG2 and INS-1E that were similar between BPA and BPS. Both increased levels of inflammatory mediators, such as metabolites pertaining to linolenic and linoleic acid metabolic pathway. In summary, this study shows that BPS also disrupts molecular functions in cells that regulate energy homeostasis, displaying similar but less pronounced responses than BPA.
Display omitted
•BPA and BPS reduced AAs and nucleosides and increased PUFAs metabolites in HepG2.•BPA altered INS1-E metabolic profile, increasing ceramides and PUFAs levels.•BPA and BPS display similar toxic effects; however, BPA has higher toxic potential.•Both BPA and BPS play key roles in regulating inflammation in HepG2 and INS-1E.
An efficient and general multiscale strategy to model rough contact and determine the evolution of the real contact area is proposed, based on the splitting of the surface power spectrum. A ...multiplicative homogenisation scheme is developed to evaluate the contact area fraction effectively, by incorporating statistical information of the contact pressure field in the scale transitions. A strategy for separating the roughness frequencies and for generating the topography at each scale is proposed. The comparison between direct numerical simulation and the proposed multiscale strategy demonstrates the capability to predict the contact area evolution of multiscale rough topographies. The significant reduction of the computational cost endorses the applicability of the proposed multiscale framework to practical circumstances.
Display omitted
•Decomposition of the surface spectrum by splitting roughness on the frequency domain using new techniques.•Multiplicative homogenisation that incorporates statistical information of the contact pressure field.•Meticulous numerical validation by comparing the results with direct numerical simulation.•Significant reduction of the computational cost while preserving the overall accuracy.
•A hybrid methanol fuel cell operating with a biosensor.•One electrode of the fuel cell is the biosensing element.•A molecularly-imprinted polymer tailored in situ for carcinoembryonic antigen.•The ...overall power of the hybrid cell is carcinoembryonic antigen concentration dependent.•This hybrid fuel cell pursues an application in point-of-care.
This work describes the development of an innovative electrochemical biosensor comprehending a passive direct methanol fuel cell (DMFC) assembly, modified by a layer of a molecularly imprinted polymer (MIP) on a carbon fabric anode electrode containing Pt/Ru nanoparticles.
This MIP film was prepared from poly(3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPy) obtained by in situ electropolymerization of the corresponding monomers on the anode electrode surface. This MIP film is designed to detect an important cancer biomarker- carcinoembryonic antigen (CEA).
This innovative, all-in-one device works in a simple way. First, CEA is incubated on the anode container of the fuel cell, then methanol is added, followed by the response evaluation (polarization curves determination). As CEA selectively interacts with the MIP film, it blocks the methanol's access to the Pt catalyst, remains specific bonded, and interferes with the subsequent polarization curves of the DMFC. Polarization curves obtained in the presence of standard solutions prepared in buffer and human serum confirmed linear responses of log CEA concentration ranging from 30 to 30 000 ng/mL in both media. The biosensor DMFC showed a sensitive response with a detection limit of 4.41 ng/mL when an aqueous 0.05 M methanol solution was used as fuel. When methanol was replaced by an ethanol solution of the same concentration (using the same setup developed for the DMFC), the lower detection limit of 3.52 ng/mL was obtained.
Overall, the obtained results show that methanol/ethanol fuel cells operating without flow-through can be successfully used for the fabrication of self-powered biosensors. The novel biosensor concept presented here is simple, inexpensive, and effective, and can be further developed to meet point-of-care requirements.
Microfluidic devices constructed using low cost materials presents as alternative for conventional flow analysis systems because they provide advantages as low consumption of reagents and samples, ...high speed of analysis, possibility of portability and the easiness of construction and maintenance. Herein, is described for the first time the use of an electrochemical biosensor for phenol detection combined with a very simple and efficient microfluidic device based on commercial textile threads. Taking advantages of capillary phenomena and gravity forces, the solution transportation is promoted without any external forces or injection pump. Screen printed electrodes were modified with carbon nanotubes/gold nanoparticles followed by covalent binding of tyrosinase. After the biosensor electrochemical characterization by cyclic voltammetry technique, the optimization of relevant parameters such as pH, potential of detection and linear range for the biosensor performance was carried out; the system was evaluated for analytical phenol detection presenting limit of detection and limit of quantification 2.94nmolL−1 and 8.92nmolL−1 respectively. The proposed system was applied on phenol addition and recovery studies in drinking water, obtaining recoveries rates between 90% and 110%.
•Tyrosinase electrochemical biosensor was combined with microfluidic thread-based device for Phenol detection.•Detection and limit of: 2.94nmolL−1 for phenol detection.•The proposed method/device was sensitive, simple, and reliable for phenol detection in tap water.
The impact of non-Gaussianity on the statistical geometry of isotropic random rough surfaces is analysed in this contribution. The non-Gaussian height distribution is modeled using the Weibull ...probability distribution. The summits height distribution, expected mean curvature and density of summits are obtained and compared with analytical solutions given by Nayak’s theory for the Gaussian case. A significant deviation from the Gaussian cases is observed. The mean curvature of negatively-skewed surfaces is found to decrease with the increase of height, contradicting the trend registered for the Gaussian case. Nayak’s parameter globally dominates the impact of the spectral properties. However, the wavelength ratio and the Hurst exponent are required to characterize the effect of the spectrum on the rough surfaces statistics.
The impact of non-Gaussian height distribution on the real contact area evolution of elastic, frictionless and non-adhesive contact is studied. The Weibull probability function is used to model the ...height distribution, as it can capture surfaces of practical relevance. The set of variables needed to parametrise the problem is discussed, including the shape parameter of the height distribution, the topography’s wavelength ratio and the Hurst exponent. As the topographies become more non-Gaussian, a significant deviation from the Gaussian case is observed. Moreover, the spectral properties show a distinct effect on different non-Gaussian surfaces and the dependency on Nayak’s parameter is not inherited. A power-law evolution of the real contact area is found to fit the numerical results obtained with the boundary element method precisely. Finally, two semi-analytical asperity-based models are compared with numerical results, using the statistics of artificially generated topographies. The qualitative behaviour predicted with the numerical simulations is captured.
PDF
