Stress is a disease of modern life generated by excess cortisol hormone levels. A paper-based microanalytical device (µPAD) was developed to analyze cortisol in human saliva samples without prior purification treatment. The design includes optimized flow channels to use freshly extracted human saliva samples. The density, viscosity, and pH properties of human saliva and artificial saliva models were characterized. These properties helped to establish optimal theoretical dimensions for our µPAD design, which works with untreated human saliva. A microfluidic engineering analysis was performed to understand the dynamics of the sample flow in the sensor, obtaining a design that allows free and rapid transport of freshly extracted human saliva, covering the surface of the µPADs in approximately three minutes. Its characteristic design allows for the direct use of human saliva without pretreatment, making it an effective tool as a universal device with multiple applications in different research fields, specifically as a point-of-care (POC) device. After the design was developed, a proof-of-concept method based on colorimetric detection of salivary cortisol, similar to enzyme-linked immunosorbent assay (ELISA) analysis, was performed using gold nanoparticles. The colorimetric response was obtained after 7 min of adding the fresh human saliva sample and the corresponding feedback after UV light lamp illumination. The authors designed a paper-based sensor that works with freshly extracted human saliva without any previous treatment for the detection of hormonal stress, generating an advance in biomolecular detection for use as a POC tool.

Estrogens have been widely shown to induce cell proliferation in breast cancer (BC) cells. Recently, we have described their involvement in the induction of epithelial–mesenchymal transition (EMT), migration, and invasion. The aim of this work is to review the molecular mechanisms by which estradiol (E₂) activates different signaling pathways, both genomic and non-genomic, through binding to different estrogen receptors (ERs), depending on the phosphorylated amino acid (Ser-118 or Tyr-537). The relevance of the present work lies in the molecular details of c-Src kinase activation by the membrane estrogen receptor (mER) and its effects on the early and late phases of EMT. This process initiates a loss of cell adhesion, leading to migration, which culminates in metastasis of cancer cells to distant tissues. Understanding how estrogens induce metastasis will facilitate the development of better strategies to counteract the lethality of BC. Finally, the quantification of Snail may serve as a molecular marker in the early stages of tumor progression, as well as the use of drugs against c-Src and ERs, as they may be therapeutic targets.

In this work, a novel nanoaptasensor (NASEc) for rapid and direct detection of Escherichia coli (E. coli) in drinking water was designed and constructed. The sensor is based on electrical conductivity measurements between a set of bare gold electrodes and a set of modified gold electrodes. The modified electrode set was covered with an aptamer layer (AE10) to improve affinity for E. coli and better binding to the electrode surface. Using the modified nanostructured layer with multiwall carbon nanotubes (MWCNT), the high sensitivity of the sensor was achieved and allowed to detect the presence of E. coli in quantities of a single colony forming units (CFU) per 100 mL. This sensitivity meets the relevant international drinking water quality standards. Each step in the process of the NASEc fabrication was verified and proved by different analytical techniques at a nanometric and molecular level: UV-vis and Raman Spectroscopy, AFM, and SEM. This portable, simple, and reusable nanoaptasensor with high selectivity and affinity offers faster detection (3 min) in the presence of E. coli compared to conventional colony forming units (CFU) counting-based methods (24 to 48 h). NASEc is designed for direct measurements without any pretreatment of samples and is helpful in potable water within a conductivity range of 50 to 1300 µS/cm. Resumen. En este trabajo, se diseñó y construyó un nuevo nanoaptasensor (NASEc) para la detección rápida y directa de Escherichia coli (E. coli) en agua potable. El sensor se basa en mediciones de conductividad eléctrica entre un conjunto de electrodos de oro sin modificar y un conjunto de electrodos de oro modificado. El conjunto de electrodos modificado se cubrió con una capa de aptámero (AE10) para mejorar la afinidad por E. coli y una mejor unión a la superficie del electrodo. Utilizando la capa nanoestructurada modificada con nanotubos de carbono de paredes múltiples (MNTC) se logró la alta sensibilidad del sensor y permitió detectar la presencia de E. coli en cantidades de una sola unidad formadora de colonias (UFC) por 100 ml. Esta sensibilidad cumple con los estándares internacionales pertinentes de calidad del agua potable. Cada paso en el proceso de fabricación de NASEc fue verificado y probado mediante diferentes técnicas analíticas a nivel nanométrico y molecular: espectroscopia UV-vis y Raman, AFM y SEM. Este nanoaptasensor portátil, simple y reutilizable con alta selectividad y afinidad ofrece una detección más rápida (3 min) en presencia de E. coli en comparación con los métodos convencionales basados ​​en el recuento de unidades formadoras de colonias (UFC) (24 a 48 h). NASEc está diseñado para mediciones directas sin ningún tratamiento previo de muestras y es útil en agua potable dentro de un rango de conductividad de 50 a 1300 µS/cm.