Microribonucleic
acids (miRNAs) have been linked with various regulatory
functions and diseases and constitute important targets in future
medical diagnostics and prognostics. We report here a novel sensitive
and rapid bioelectrochemical strategy for miRNA determination. This
strategy involves the development of a sensing approach making use
of magnetic beads (MBs) modified with a specific DNA-RNA antibody
as capture bioreceptor and amperometric detection implying the H2O2/hydroquinone (HQ) system at disposable screen-printed
carbon electrodes (SPCEs). The developed biosensor exhibits a dynamic
range from 8.2 to 250 pM and a detection limit of 2.4 pM (60 amol)
of a synthetic target without any amplification step in 2 h. The usefulness
of the approach was evaluated by analyzing total RNA (RNAt) extracted from metastatic cancer cell lines and human tumor tissues,
which demonstrated its potential to perform determination of mature
miRNAs in these complex samples. Moreover, the feasibility of the
developed methodology to detect simultaneously the expression of two
different miRNAs at dual SPCEs (SPdCEs) in one single experiment was
also explored. The feasibility to capture and release target miRNAs
make the developed methodology also an attractive tool to isolate,
purify, and determine target miRNAs with great applicability in the
clinical field.
The first electrochemical immunosensor for the determination of fibroblast growth factor receptor 4 (FGFR4) biomarker is reported in this work. The biosensor involves a sandwich configuration with covalent immobilization of a specific capture antibody onto activated carboxylic-modified magnetic microcarriers (HOOC-MBs) and amperometric detection at disposable carbon screen-printed electrodes (SPCEs). The biosensor exhibits a great analytical performance regarding selectivity for the target protein and a low LOD of 48.2 pg mL-1. The electrochemical platform was successfully applied for the determination of FGFR4 in different cancer cell lysates without any apparent matrix effect after a simple sample dilution and using only 2.5 μg of the raw lysate. Comparison of the results with those provided by a commercial ELISA kit shows competitive advantages by using the developed immunosensor in terms of simplicity, analysis time, and portability and cost-affordability of the required instrumentation for the accurate determination of FGFR4 in cell lysates.
Solar absorbers in a three-layer configuration have been prepared by dip-coating onto aluminium substrates. They are constituted by two spinel layers with one silica layer on the top and values of solar absorptance above 0.950 and thermal emittance below 0.04 were obtained. The effects of using different sintering conditions of the upper silica layer on the optical behaviour and durability tests have been studied. Results obtained in accelerated ageing methods, such as thermal stability tests and condensation tests, clearly show that the proposed selective absorber exhibits excellent thermal stability and very good humidity resistance. The results show that the protective action is due not only to the silica layer but also to the alumina layer produced during the absorber preparation. The phase composition of the individual layers was independently confirmed using X-ray diffraction and corroborated by X-ray Photoelectron Spectroscopy. Spinel-like phases were obtained in both the first and second layers. The ageing study shows that the three-layer configuration proposed has a very high potential, in terms of both durability and optical behaviour, for solar thermal low-temperature applications.
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