22 research outputs found
Passive direct methanol fuel cells acting as fully autonomous electrochemical biosensors: Application to sarcosine detection
This work describes an innovative electrochemical biosensor that advances its autonomy toward an equipment-free design. The biosensor is powered by a passive direct methanol fuel cell (DMFC) and signals the response via an electrochromic display. Briefly, the anode side of the DMFC power source was modified with a biosensor layer developed using molecularly imprinted polymer (MIP) technology to detect sarcosine (an amino acid derivative that is a potential cancer biomarker). The biosensor layer was anchored on the surface of the anode carbon electrode (carbon black with Pt/Ru, 40:20). This was done by bulk radical polymerization with acrylamide, bis-acrylamide, and vinyl phosphonic acid. This layer selectively interacted with sarcosine when integrated into the passive DMFC (single or multiple, in a stack of 4), which acted as a transducer element in a concentration-dependent process. Serial assembly of a stack of hybrid DMFC/biosensor devices triggered an external electrochromic cell (EC) that produced a colour change. Calibrations showed a concentration-dependent sarcosine response from 3.2 to 2000 µM, which is compatible with the concentration of sarcosine in the blood of prostate cancer patients. The final DMFC/biosensor-EC platform showed a colour change perceptible to the naked eye in the presence of increasing sarcosine concentrations. This colour change was controlled by the DMFC operation, making this approach a self-controlled and self-signalling device.
Overall, this approach is a proof-of-concept for a fully autonomous biosensor powered by a chemical fuel. This simple and low-cost approach offers the potential to be deployed anywhere and is particularly suitable for point-of-care (POC) analysis.The authors acknowledge the financial support of EU-Horizon 2020 (Symbiotic, FET-Open, GA665046), and from national funds from FCT - Fundação para a Ciência e a Tecnologia, I.P., in the scope of the projects LA/P/0037/2020, UIDP/50025/2020, UIDB/50025/2020 and UID/EMS/00532/2019. Nádia Ferreira (SFRH/BD/122955/2016), Liliana Carneiro (SFRH/BD/122954/2016), and Ana Carolina Marques (SFRH/BD/115173/2016) acknowledge Fundação para a Ciência e Tecnologia (FCT) for financial support.info:eu-repo/semantics/publishedVersio
Molecular velocity auto-correlation of simple liquids observed by NMR MGSE method
The velocity auto-correlation spectra of simple liquids obtained by the NMR
method of modulated gradient spin echo show features in the low frequency range
up to a few kHz, which can be explained reasonably well by a long
time tail decay only for non-polar liquid toluene, while the spectra of polar
liquids, such as ethanol, water and glycerol, are more congruent with the model
of diffusion of particles temporarily trapped in potential wells created by
their neighbors. As the method provides the spectrum averaged over ensemble of
particle trajectories, the initial non-exponential decay of spin echoes is
attributed to a spatial heterogeneity of molecular motion in a bulk of liquid,
reflected in distribution of the echo decays for short trajectories. While at
longer time intervals, and thus with longer trajectories, heterogeneity is
averaged out, giving rise to a spectrum which is explained as a combination of
molecular self-diffusion and eddy diffusion within the vortexes of hydrodynamic
fluctuations.Comment: 8 pages, 6 figur
Crescimento e sobrevivência de mudas de cagaiteira (Eugenia dysenterica DC) nas condições do cerrado
Embebição e posição da semente na germinação de clones de porta-enxertos de cajueiro-anão-precoce
Variabilidade genética de germoplasma tradicional de feijoeiro comum na região de Cáceres-MT
In vitro multiplication of 'Flordaguard' rootstock: cytokinin source and concentration effects, explants orientation and period of permanence in the culture medium
Água salina e esterco bovino líquido na formação de mudas de goiabeira cultivar Paluma
Biodiversidade e distribuição das diatomáceas (Bacillariophyceae) de sedimentos superficiais nos reservatórios em cascata do rio Paranapanema, SP/PR, Brasil
An all-in-one approach for self-powered sensing: A methanol fuel cell modified with a molecularly imprinted polymer for cancer biomarker detection
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.The authors acknowledge the financial support of EU-Horizon 2020 (Symbiotic, FET-Open, GA665046) and LPTC (Grant reference SFRH/ BD/122954/2016) acknowledge Fundação para a Ciência e Tecnologia for the financial support. POCI (FEDER) also supported this work via CEFT, project UIDP/00532/2020.info:eu-repo/semantics/publishedVersio