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Polypyrrole (PPy) nanorods (NRs) and nanoparticles (NPs) are synthesized via electrochemical and chemical methods, respectively, and tested upon ammonia exposure using Raman and X-ray photoelectron spectroscopy (XPS). Characterization of both nanomaterials via Raman spectroscopy demonstrates the formation of PPy, displaying vibration bands consistent with the literature. Additionally, XPS reveals the presence of neutral PPy species as major components in PPy NRs and PPy NPs, and other species including polarons and bipolarons. Raman and XPS analysis after ammonia exposure show changes in the physical/chemical properties of PPy, confirming the potential of both samples for ammonia sensing. Results demonstrate that the electrochemically synthesized NRs involve both proton and electron transfer mechanisms during ammonia exposure, as opposed to the chemically synthesized NPs, which show a mechanism dominated by electron transfer. Thus, the different detection mechanisms in PPy NRs and PPy NPs appear to be connected to the particular morphological and chemical composition of each film. These results contribute to elucidate the mechanisms involved in ammonia detection and the influence of the synthesis routes and the physical/chemical characteristics of PPy.

The aim of this review is to summarize the recent progress in the fabrication of efficient nanostructured polymer-based sensors with special focus on polypyrrole. The correlation between physico-chemical parameters, mainly morphology of various polypyrrole nanostructures, and their sensitivity towards selected gas and volatile organic compounds (VOC) is provided. The different approaches of polypyrrole modification with other functional materials are also discussed. With respect to possible sensors application in medicine, namely in the diagnosis of diseases via the detection of volatile biomarkers from human breath, the sensor interaction with humidity is described as well. The major attention is paid to analytes such as ammonia and various alcohols.

Love wave sensors with silver-modified polypyrrole nanoparticles are developed in this work. These systems prove functional at room temperature with enhanced response, sensitivity and response time, as compared to other state-of-the-art surface acoustic wave (SAW) sensors, towards volatile organic compounds (VOCs). Results demonstrate the monitoring of hundreds of ppb of compounds such as acetone, ethanol and toluene with low estimated limits of detection (~3 ppb for acetone). These results are attributed to the use of silver-modified polypyrrole as a second guiding/sensitive layer in the Love wave sensor structure, which provides further chemically active sites for the gas-solid interactions. The sensing of low VOCs concentrations by micro sensing elements as those presented here could be beneficial in future systems for air quality control, food quality control or disease diagnosis via exhaled breath as the limits of detection obtained are within those required in these applications.

The research is focused on water disinfection via new technological concept based on smart combination of nanostructured TiO 2 layer and silver nanoparticles (Ag NPs). The TiO 2 /Ag NPs photocatalytic system was created via anodization of Ti thin film and subsequent UV-assisted and electrochemical pulse deposition of Ag NPs. Morphology of TiO 2 /Ag NPs system was studied via scanning electron microscopy (SEM). Its efficiency was evaluated on photocatalytic degradation of yeast Candida glabrata . Graphical abstract

Highly ordered TiO 2 nanotube arrays were fabricated by anodic oxidation of titanium thin film in organic electrolyte containing ammonium fluoride and water. The effect of electrolyte composition as well as sputter deposition parameters of titanium thin film on morphology of nanotubes was observed by scanning electron microscopy (SEM) and surface chemical analysis by X-ray photoelectron spectroscopy (XPS). The electrolyte composition was optimized to reach the balance between anodic oxidation and chemical etching of initial oxide barrier layer, leading to freestanding and highly ordered open nanotubes with lengths in the range of 400–800 nm. Further these surfaces of nanostructured titania may be easily decorated with broad spectrum of nanoparticles or various functional materials according to required applications. Graphical abstract

The fabrication of self-ordered semiconductor (TiO2) and noble metal (Au) QDs arrays was successfully achieved by advanced nonlithographic template based method, namely using nanoporous alumina template. The emphasis was placed on the successful preparation of QDs arrays with the desired size, homogeneous distribution and optical (especially fluorescence) properties. Titania and gold QDs characterization by SEM, EDX and fluorescence spectroscopy was performed in order to verify their surface topography, chemical composition and emission properties in UV/VIS range of spectra, respectively. The surface biofunctionalization of QDs was realized via simple physical adsorption of glutathione tripeptide, which makes these arrays suitable for potential biosensing application, mainly in optical and electrochemical detection of biomolecules in vitro.

In this study, we compared two types of nanostructured electrodes with gold nanocolumns and flat gold electrodes by measurements with doxorubicin. Nanostructured electrodes were fabricated by electrochemical anodic oxidation followed by deposition of gold to the porous alumina. Flat gold electrodes were fabricated by physical evaporation of gold layer to the silicon substrate. All electrodes were characterized by electrochemical impedance spectroscopy and then the electrochemical determination of doxorubicin was studied by differential pulse voltammetry. The impedance spectroscopy measurements proved a bigger electroactive area for nanostructured electrodes. The gold nanocolumns have been found as an important factor in increasing of electrodes active area. This fact is very important for sensors sensitivity. Fabricated electrodes were successfully used for determination of doxorubicin.

The fabrications of iron oxides nanoparticles using co-precipitation and gadolinium nanoparticles using water in oil microemulsion method are reported in this paper. Results of detailed phase analysis by XRD and Mössbauer spectroscopy are discussed. XRD analysis revealed that the crystallite size (mean coherence length) of iron oxides (mainly γ-Fe2O3) in the Fe2O3 sample was 30 nm, while in Fe2O3/SiO2 where the ε-Fe2O3 phase dominated it was only 14 nm. Gd/SiO2 nanoparticles were found to be completely amorphous, according to XRD. The samples showed various shapes of hysteresis loops and different coercivities. Differences in the saturation magnetization (MS) correspond to the chemical and phase composition of the sample materials. However, we observed that MS was not reached in the case of Fe2O3/SiO2, while for Gd/SiO2 sample the MS value was extremely low. Therefore we conclude that only unmodified Fe2O3 nanoparticles are suitable for intended biosensing application in vitro (e.g. detection of viral nucleic acids) and the phase purification of this sample for this purpose is not necessary.

Nowadays, nanoparticles are in the centre of interest but their toxicity has not been explored much yet. Because of their small dimensions, nanoparticles can get through cell walls or on the other side eliminate from organism uneasily. Even if nanoparticles do not show any acute toxicity, there are still unanswered questions about their long term effects, bioaccumulation and influences on substance structure. The mechanism of nanotoxicity has been unexplored but there is a relation with chemical composition, structure, size and surface of nanoparticles. Toxicity of nanoparticles can be educed in two ways: - from chemical toxicity on the basis of chemical composition, e.g. releasing of toxic ions, - stress or stimuli caused by the surface, size or shape of the particles.

A biphasic solvothermal reaction method has been used for the synthesis of TiO 2 nanoparticles (NPs). In this method, hydrolysis and nucleation occur at the interface of organic phase (titanium (IV) n -propoxide and stearic acid dissolved in toluene) and water phase ( tert -butylamine dissolved in water) resulting in the nucleation of the stearic acid-capped TiO 2 NPs. These NPs are hydrophilic due to hydrophobic stearic acid ligands and could be dispersed in toluene, but not in water. These stearic acid-capped TiO 2 NPs were surface-modified with 2,3-dimercaptosuccinic acid (DMSA) in order to make them water soluble. The resultant TiO 2 NPs were easily redispersed in water without any noticeable aggregation. The Rietveld profile fitting of X-ray diffraction (XRD) pattern of the TiO 2 NPs revealed highly crystalline anatase structure. The average crystallite size of TiO 2 NPs was calculated to be 6.89 nm, which agrees with TEM results. These results have important implications for the use of TiO 2 in biomedical, environmental, and industrial applications.