Polypyrrole one-dimensional nanostructures (nanotubes, nanobelts and nanofibers) were prepared using three various dyes (Methyl Orange, Methylene Blue and Eriochrome Black T). Their high electrical conductivity (from 17.1 to 60.9 S cm-1), good thermal stability (in the range from 25 to 150 °C) and resistivity against ageing (half-time of electrical conductivity around 80 days and better) were used in preparation of lightweight and flexible composites with silicone for electromagnetic interference shielding in the C-band region (5.85-8.2 GHz). The nanostructures' morphology and chemical structure were characterized by scanning electron microscopy, Brunauer-Emmett-Teller specific surface measurement and attenuated total reflection Fourier-transform infrared spectroscopy. DC electrical conductivity was measured using the Van der Pauw method. Complex permittivity and AC electrical conductivity of respective silicone composites were calculated from the measured scattering parameters. The relationships between structure, electrical properties and shielding efficiency were studied. It was found that 2 mm-thick silicone composites of polypyrrole nanotubes and nanobelts shield almost 80% of incident radiation in the C-band at very low loading of conductive filler in the silicone (5% w/w). Resulting lightweight and flexible polypyrrole composites exhibit promising properties for shielding of electromagnetic interference in sensitive biological and electronic systems.
- MeSH
- Azo Compounds chemistry MeSH
- Electromagnetic Radiation * MeSH
- Methylene Blue chemistry MeSH
- Microscopy, Electron, Scanning MeSH
- Nanostructures chemistry radiation effects ultrastructure MeSH
- Nanotubes chemistry radiation effects ultrastructure MeSH
- Nanofibers chemistry radiation effects MeSH
- Polymers chemistry radiation effects MeSH
- Pyrroles chemistry radiation effects MeSH
- Silicones chemistry radiation effects MeSH
- Publication type
- Journal Article MeSH
In this study, a highly sensitive, fast, and selective enzyme-free electrochemical sensor based on the deposition of Ni cavities on conductive glass was proposed for insulin detection. Considering the growing prevalence of diabetes mellitus, an electrochemical sensor for the determination of insulin was proposed for the effective diagnosis of the disease. Colloidal lithography enabled deposition of nanostructured layer (substrate) with homogeneous distribution of Ni cavities on the electrode surface with a large active surface area. The morphology and structure of conductive indium tin oxide glass modified with Ni cavities (Ni-c-ITO) were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The diameter of the resulting cavities was approximately 500 nm, while their depth was calculated at 190 ± 4 nm and 188 ± 18 nm using AFM and SEM, respectively. The insulin assay performance was evaluated by cyclic voltammetry. Ni-c-ITO exhibited excellent analytical characteristics, including high sensitivity (1.032 μA μmol-1 dm3), a low detection limit (156 μmol dm-3), and a wide dynamic range (500 nmol dm-3 to 10 μmol dm-3). Finally, the determination of insulin in buffer with interferents and in real blood serum samples revealed high specificity and demonstrated the practical potential of the method.
Lead contamination is now widespread, and exposure to lead may cause adverse effects on human beings. In this study, a photoelectrochemical sensor based on flower-like ZnO nanostructures was developed for Pb(2+) detection, using a Pb(2+)-dependent DNAzyme as the recognition unit and a double-strand DNA intercalator, Ru(bpy)2(dppz)(2+) (bpy=2,2'-bipyridine, dppz=dipyrido[3,2-a:2',3'-c] phenazine) as the photoelectrochemical signal reporter. The ZnO nanoflower was fabricated on an indium tin oxide (ITO) electrode by the convenient hydrothermal decomposition method. The morphology and photoelectrochemical property of the ZnO nanoflowers were characterized by SEM, XRD and photocurrent measurements. DNAzyme-substrate duplex was assembled on an ITO/ZnO electrode through electrostatic adsorption. In the presence of Pb(2+), RNA-cleavage activity of the DNAzyme was activated and its substrate strand was cleaved, resulting in the release of Ru(bpy)2(dppz)(2+) from the DNA film and the concomitant photocurrent decrease. The detection principle was verified by fluorescence measurements. Under the optimized conditions, a linear relationship between photocurrent and Pb(2+) concentration was obtained over the range of 0.5-20 nM, with a detection limit of 0.1 nM. Interference from other common metal ions was found negligible. Applicability of the sensor was demonstrated by analyzing lead level in human serum and Pb(2+) spiked water samples. This facile and economical sensor system showed high sensitivity and selectivity, thus can be potentially applied for on-site monitoring of lead contaminant.
- MeSH
- Biosensing Techniques instrumentation MeSH
- Water Pollutants, Chemical analysis MeSH
- Equipment Design MeSH
- DNA, Catalytic chemistry MeSH
- Electrochemical Techniques instrumentation MeSH
- Intercalating Agents chemistry MeSH
- Lakes analysis MeSH
- Limit of Detection MeSH
- Nanostructures chemistry ultrastructure MeSH
- Lead analysis MeSH
- Zinc Oxide chemistry MeSH
- Drinking Water analysis MeSH
- Publication type
- Journal Article MeSH
- Evaluation Study MeSH
- Research Support, Non-U.S. Gov't MeSH
With the growing numbers of nanomaterials (NMs), there is a great demand for rapid and reliable ways of testing NM safety-preferably using in vitro approaches, to avoid the ethical dilemmas associated with animal research. Data are needed for developing intelligent testing strategies for risk assessment of NMs, based on grouping and read-across approaches. The adoption of high throughput screening (HTS) and high content analysis (HCA) for NM toxicity testing allows the testing of numerous materials at different concentrations and on different types of cells, reduces the effect of inter-experimental variation, and makes substantial savings in time and cost. HTS/HCA approaches facilitate the classification of key biological indicators of NM-cell interactions. Validation of in vitro HTS tests is required, taking account of relevance to in vivo results. HTS/HCA approaches are needed to assess dose- and time-dependent toxicity, allowing prediction of in vivo adverse effects. Several HTS/HCA methods are being validated and applied for NM testing in the FP7 project NANoREG, including Label-free cellular screening of NM uptake, HCA, High throughput flow cytometry, Impedance-based monitoring, Multiplex analysis of secreted products, and genotoxicity methods-namely High throughput comet assay, High throughput in vitro micronucleus assay, and γH2AX assay. There are several technical challenges with HTS/HCA for NM testing, as toxicity screening needs to be coupled with characterization of NMs in exposure medium prior to the test; possible interference of NMs with HTS/HCA techniques is another concern. Advantages and challenges of HTS/HCA approaches in NM safety are discussed. WIREs Nanomed Nanobiotechnol 2017, 9:e1413. doi: 10.1002/wnan.1413 For further resources related to this article, please visit the WIREs website.
- MeSH
- Cell Line MeSH
- Cytological Techniques MeSH
- Intracellular Space chemistry metabolism MeSH
- Humans MeSH
- Mice MeSH
- Nanostructures toxicity MeSH
- High-Throughput Screening Assays methods MeSH
- Toxicity Tests methods MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
