Electrospun Composite Bead-on-String Nanofibers Containing CaO₂ Nanoparticles and MnO₂ Nanosheets as Oxygen-Release Systems for Biomedical Applications

Oxygen-generating biomaterials have the potential to improve tissue engineering and regenerative therapeutic strategies. However, the development of such materials capable of controlling the local partial pressure of oxygen (pO2) in the long term is still a major challenge. Here we report nanostructured composite membranes comprising electrospun fibers exhibiting a bead-on-string structure as a controlled oxygen-release system for periodontitis treatment. For this, calcium peroxide nanoparticles (CaO2 NPs) and manganese dioxide nanosheets (MnO2 NSs) were incorporated into the structure of hydrophobic electrospun poly (lactic acid) (PLA)-based nanofibers. We use CaO2 NPs as hydrogen peroxide (H2O2)-generating precursors when exposed to water, while MnO2 NSs were applied as a nanozyme to catalyze the decomposition of H2O2 to the final oxygen product. Our results revealed that the beads on the fibrous structure acted as reservoirs of CaO2 NPs and MnO2 NSs. Moreover, the composite membranes provided sustained oxygen release over 7 days, where levels were modulated by the CaO2 NP content. Such constructs exhibited suitable physicochemical properties and antimicrobial activities against some bacteria (e.g., Porphyromonas gingivalis and Treponema denticola) typically associated with aggressive and chronic periodontitis. In vitro studies also revealed that the membranes were not cytotoxic toward human oral keratinocyte (Nok-si) cells as well as enhanced the cell viability when high content of CaO2 NP and MnO2 NS were incorporated into the fiber’s structure. Taken together, our results demonstrate that the nanostructured composite membranes show potential to be employed as oxygen-release platforms for periodontal tissue regeneration

Electrospun Polyamide 6/Poly(allylamine hydrochloride) Nanofibers Functionalized with Carbon Nanotubes for Electrochemical Detection of Dopamine

The use of nanomaterials as an electroactive medium has improved the performance of bio/chemical sensors, particularly when synergy is reached upon combining distinct materials. In this paper, we report on a novel architecture comprising electrospun polyamide 6/poly­(allylamine hydrochloride) (PA6/PAH) nanofibers functionalized with multiwalled carbon nanotubes, used to detect the neurotransmitter dopamine (DA). Miscibility of PA6 and PAH was sufficient to form a single phase material, as indicated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), leading to nanofibers with no beads onto which the nanotubes could adsorb strongly. Differential pulse voltammetry was employed with indium tin oxide (ITO) electrodes coated with the functionalized nanofibers for the selective electrochemical detection of dopamine (DA), with no interference from uric acid (UA) and ascorbic acid (AA) that are normally present in biological fluids. The response was linear for a DA concentration range from 1 to 70 μmol L^–1, with detection limit of 0.15 μmol L^–1 (S/N = 3). The concepts behind the novel architecture to modify electrodes can be potentially harnessed in other electrochemical sensors and biosensors

Information Visualization and Feature Selection Methods Applied to Detect Gliadin in Gluten-Containing Foodstuff with a Microfluidic Electronic Tongue

The fast growth of celiac disease diagnosis has sparked the production of gluten-free food and the search for reliable methods to detect gluten in foodstuff. In this paper, we report on a microfluidic electronic tongue (e-tongue) capable of detecting trace amounts of gliadin, a protein of gluten, down to 0.005 mg kg^–1 in ethanol solutions, and distinguishing between gluten-free and gluten-containing foodstuff. In some cases, it is even possible to determine whether gluten-free foodstuff has been contaminated with gliadin. That was made possible with an e-tongue comprising four sensing units, three of which made of layer-by-layer (LbL) films of semiconducting polymers deposited onto gold interdigitated electrodes placed inside microchannels. Impedance spectroscopy was employed as the principle of detection, and the electrical capacitance data collected with the e-tongue were treated with information visualization techniques with feature selection for optimizing performance. The sensing units are disposable to avoid cross-contamination as gliadin adsorbs irreversibly onto the LbL films according to polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) analysis. Small amounts of material are required to produce the nanostructured films, however, and the e-tongue methodology is promising for low-cost, reliable detection of gliadin and other gluten constituents in foodstuff