RESUMEN
This study unveils a novel electrochemical biosensor for monitoring glucose in biological fluids by employing nanorods of a cobalt-bispyridyl/dicarboxylate framework grown in a layer-by-layer manner on a highly porous nickel substrate. The hybrid microporous system has a bicatalytic effect on glucose oxidation due to the synergistic catalytic impact of the nickel and cobalt ions with varying oxidation states as electroactive sites. In addition, the controlled growth of inorganic-organic frameworks changes the mechanism of electron transfer from a diffusion-controlled process to an adsorption-controlled process, thus yielding a low onset oxidation potential (â¼0.21 V/Ag-AgCl) and a high current intensity (â¼1 mA) for the oxidation of glucose in alkaline media. A fast response time (â¼2 s) and a reasonably high sensitivity (0.14 µA µM-1) within a broad linear range (40-360 µM) have determined the suitability and superiority of the hybrid electrode for glucose monitoring compared to many metal-organic-based biosensors. The facile fabrication process of the Co(II) coordination polymer/Ni substrate with a large surface area that benefits from the synergetic catalytic activity of nickel-cobalt hybrids may pave the way for the development of novel hybrid electrodes for biosensors and direct glucose fuel cells.
RESUMEN
We present a strategy for electrochemical measurements using a durable minute bubble wall with a thickness of 27 µm (D = 1.8 cm) as an innovative electrochemical medium. The composition, thickness, and volume of the tiny bubble film were investigated and estimated using the spectroscopic method and the Beer-Lambert law. A carbon microelectrode (D = 10 µm) was then employed as the working electrode, inserted through the bubble wall to function as the solution interface. First, the potential of this method for microelectrodeposition of metallic Ag and Pd films in a tiny bubble was investigated. Interestingly, microscopic images of the deposited film clearly demonstrated that the bubble thickness determines and confines the electrochemical deposition zone. In other words, innovative template-free microelectrodeposition was achieved. In the second phase of our work, microelectroanalysis of trace levels of nitrite ions was performed within the bubble wall and on a foam-covered hand, between the fingers directly, with a low limit of detection of 28 µM. This technique holds significance in criminal investigations, as the presence of NO2- ions on the hand indicates the potential presence of gunshot residue and aids in identifying suspects. In comparison to current methods, this approach is rapid, simple, cost-effective, and amenable to on-site applications, eliminating the need for sample treatment. Ultimately, the utilization of a bubble wall as a novel electrochemical microreactor can open new ways in microelectrochemical analysis, presenting novel opportunities and applications in the field of electrochemical sensors.
RESUMEN
"Micro-Nanofabricated Sensors for Bioanalysis" represents a cutting-edge field in biosensing technology which leverages the integration of micro- and nanoscale fabrication techniques [...].