Bioanalytical methods, in particular electrochemical biosensors, are increasingly used in different industrial sectors due to their simplicity, low cost, and fast response. However, to be able to reliably use this type of device, it is necessary to undertake in-depth evaluation of their fundamental analytical parameters. In this work, analytical parameters of an amperometric biosensor based on covalent immobilization of glucose oxidase (GOx) were evaluated. GOx was immobilized using plasma-grafted pentafluorophenyl methacrylate (pgPFM) as an anchor onto a tailored HEMA-co-EGDA hydrogel that coats a titanium dioxide nanotubes array (TiO2NTAs). Finally, chitosan was used to protect the enzyme molecules. The biosensor offered outstanding analytical parameters: repeatability (RSD = 1.7%), reproducibility (RSD = 1.3%), accuracy (deviation = 4.8%), and robustness (RSD = 2.4%). In addition, the Ti/TiO2NTAs/ppHEMA-co-EGDA/pgPFM/GOx/Chitosan biosensor showed good long-term stability; after 20 days, it retained 89% of its initial sensitivity. Finally, glucose concentrations of different food samples were measured and compared using an official standard method (HPLC). Deviation was lower than 10% in all measured samples. Therefore, the developed biosensor can be considered to be a reliable analytical tool for quantification measurements.
Biofilm formation in medical devices represents one of the major problems for the healthcare system, especially those that occur on implantable silicone-based devices. To provide a general solution to avoid biofilm formation in the first stages of development, this work studied how nanostructured metallic silver coatings hinder bacteria-surface interaction by preventing bacteria adhesion. The three studied silver nanostructures ("Sharp blades", "Thick blades" and "Leaves") combined superhydrophobic behavior with a physical impediment of the coating nanostructure that produced a bacteriophobic effect avoiding the adhesion mechanism of different bacterial strains. These silver nanostructures are immobilized on stretchable substrates through a polymeric thin film of plasma-polymerized penta-fluorophenyl methacrylate. The control over the nanostructures and therefore its bacteriophobic-bactericidal effect depends on the plasma polymerization conditions of the polymer. The characterization of this bacteriophobic effect through FE-SEM microscopy, live/dead cell staining, and direct bacterial adhesion counts, provided a complete mapping of how bacteria interact with the surface in each scenario. Results revealed that the bacterial adhesion was reduced by up to six orders of magnitude in comparison with uncoated surfaces thereby constituting an effective strategy to avoid the formation of biofilm on medical materials.
Strain sensors for wearable electronic devices have received attention due to their potential application in medicine for physiological monitoring or as part of advanced prosthetics. However, low sensitivity values as well as complex fabrication procedures remain significant challenges limiting the applicability. This work presents the fabrication of a strain sensor based on the separation of silver microplates immobilized on a stretchable substrate. The deposition of the microplates is achieved through the exposition of a glucosamine‐functionalized surface to the Tollens’ reagent, being a versatile fabrication methodology able to be implemented in a wide range of substrates. The obtained sensors present a high stretchability (>100%), high conductivity (105 S m–1), good linearity (R2 > 0.98 under 30% strain), good hysteresis properties, and high sensitivity (up to GF = 900 000). Hence, the sensors allow the measurement of very small deformations even in dynamic range, where it presents a stable linear response for the quantification of cyclic deformations of 0.02% strain. Moreover, the applicability of these sensors has been studied in motion‐sensing devices and in a pressure sensor revealing that this technology may expand the potential applications of wearable electronic devices.
1 September 2019 in Colloids and Surfaces B: Biointerfaces