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Low environmental stability of ZnO nanostructures in hydrophilic systems is a crucial factor limiting their practical applications. ZnO nanomaterials need surface passivation with different water-insoluble compounds. This study describes a one-step passivation process of polycrystalline ZnO films with ZnS as a facile method of ZnO surface coating. A simple sulfidation reaction was carried out in gas-phase H2S and it resulted in formation of a ZnS thin layer on the ZnO surface. The ZnS layer not only inhibited the ZnO dissolving process in water but additionally improved its mechanical and electrical properties. After the passivation process, ZnO/ZnS films remained stable in water for over seven days. The electrical conductivity of the ZnO films increased about 500-fold as a result of surface defect passivation and the removal of oxygen molecules which can trap free carriers. The nanohardness and Young's modulus of the samples increased about 64% and 14%, respectively after the ZnS coating formation. Nanowear tests performed using nanoindentation methods revealed reduced values of surface displacements for the ZnO/ZnS system. Moreover, both ZnO and ZnO/ZnS films showed antimicrobial properties against Escherichia coli.

Molecular and vibrational dynamics of a new-generation lipophilic calcium channel blocker lacidipine (LCDP) are thoroughly explored by combining solid-state nuclear magnetic resonance (NMR) with high-flux quasi-elastic (QENS) and inelastic neutron scattering (INS) experiments. Contrary to the dynamically averaged 13C CP/MAS NMR response, neutron vibrational spectroscopy confirms our previous findings on the thermodynamically stable structure. High-resolution low-wavenumber INS spectrum is reported and fully interpreted based on periodic density functional theory (DFT) calculations in the quasi-harmonic approximation, staying in excellent agreement with the experiment. The INS spectrum was found to be clearly dominated by CH3 torsional features, widely spread over the range of 5–35 meV. 1H NMR relaxation indicates a molecular reorientation with different correlation times. The NMR relaxometry was further combined with an extended QENS study, providing a quantitative description of the intramolecular motions in terms of their activation barriers and correlation times, while their assignment was fully supported by theoretical analysis. While the internal dynamics of side-chain methyl groups can be described by rotation about the threefold-axes, the high-resolution QENS measurements give evidence of rotational tunneling of 2,6-methyl groups at low temperature. The vibrational analysis suggests that strong coupling of methyl librations with lattice modes promotes such an intriguing quantum effect.

The mechanical and optical properties of Si and TiO2–Si nanopillars (NPl) were investigated. Mesoporous silicon NPl arrays were fabricated by metal-assisted chemical etching and nanosphere lithography, and then pillars were covered by TiO2 using the atomic layer deposition technique. We performed scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), Raman spectroscopy, reflectance, photoluminescence (PL) spectroscopy and nanoindentation to characterize the as-prepared and annealed TiO2–Si NPl. The main structural and mechanical parameters of TiO2–Si NPl (grain size, strain, critical load, elastic recovery and Young's module) were calculated. Reflectance and PL spectroscopy were used to study the impact of morphology on optical properties of TiO2–Si NPl before and after annealing. It was established that the nanostructures of TiO2 penetrated inside the porous matrix of Si pillar improve the mechanical properties of TiO2–Si NPl. The results of nanoindentation study have shown that Young's modulus of annealed TiO2–Si NPl is about three times higher than for the pure Si NPl.

Multimodal imaging based on nanostructures has become a subject of interest for numerous biomedical laboratories. The main focus was placed on applying nanocrystals for the purpose of two types of clinical imaging (contrast and fluorescent agents) due to their excellent luminescence and/or paramagnetic properties. Such systems should also be characterized by low toxicity and high cellular uptake efficiency. Since bare rare earth fluoride nanocrystals influence the cell membrane integrity, it is expected that their coatings will improve biocompatibility profile, as well as increase hydrophilicity, dispersion and chemical stability. Hence, by synthesis of β-NaGdF4:Yb3+Er3+ nanorods (NRs) coated with noncovalently bounded polyethylene glycol monooleate (PEG-Mo), it should be possible to obtain multimodal imaging biomarkers meeting established criteria. Synthesis of β-NaGdF4:Yb3+Er3+@PEG-Mo NRs was performed by the co-precipitation method. These nanostructures were characterized in terms of their size, morphology, zeta potential, magnetic and optical properties as well as their cytotoxicity profile and cellular internalization was evaluated. It was shown that the shape and size of nanocrystals, namely 20 nm nanorods, present generally accepted parameters for biomedical purpose. Ligand attraction of PEG-Mo 860 resulted in the encapsulation of oleic acid coated NRs and formation of hydrophilic bilayer. Superparamagnetic and luminescence properties were highly efficient. Cytotoxic profiles of normal and cancer cell lines were low and determined by dose and time. Cellular uptake was confirmed by the presence of upconversion luminescence in cell interior. These findings are showing multimodal imaging properties of rod shaped β-NaGdF4:Yb3+Er3+@PEG-Mo NRs which may be useful in some biomedical applications.

This study examines the use of oxidized multi-walled carbon nanotube/iron (O-MWCNT/Fe) nanohybrids modified with polyethylene glycol (PEG) as multifunctional cellular imaging agents for magnetic resonance imaging (MRI) and fluorescence microscopy. The PEGylated MWCNTs with embedded iron particles were investigated as T2-weighted contrast agents for MRI. The number of PEG molecules attached to the MWCNT surface was calculated. The PEG–MWCNT/Fe complex was characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared and Raman spectroscopies. Covalent surface modification of the MWCNTs improves their solubility and enables the attachment of further biomolecules to their surface. The PEGylated nanostructures were labeled with the MDC organic dye and internalized inside HeLa cells for cellular imaging. Additionally, the minimal cytotoxic effect of PEGylated complexes in comparison to non-PEGylated samples was measured using the WST-1 test and an In Cell Analyzer. A confocal microscopy study of the organelle morphology also confirmed that the HeLa cell morphology was unchanged after treatment with PEGylated MWCNTs.

Magnetic nanoparticles (MNP) coated with bioinspired polydopamine (PDA) were obtained via a co-precipitation method and oxidative polymerization of dopamine. Nanoparticles were investigated by FTIR, TEM and SQUID. Loading capacity of anticancer drug doxorubicin was determined by UV-Vis spectroscopy. The nanocomposites exhibit a high drug loading capacity of 0.46 mg mg−1. Anticancer activity of the nanocomposites was proved in profound in vitro tests on HeLa cells. Cytotoxicity and internalization of nanoparticles were checked using various method, i.e. proliferation assay (WST-1), a two-colour fluorescence cell viability assay, and fluorescent and confocal microscopy.

In the present work we demonstrate a simple and effective way to produce bulk quantities of graphene material. For the first time, graphite oxide (GO), synthesized by electrochemical treatment of natural graphite in HClO4 aqueous solution, was used to obtain thermally exfoliated-reduced graphite oxide (TRGO). Herein, GO was thermally exfoliated and reduced at 500 °C in air, giving the final product of TRGO. Due to shock treatment, the volume of the synthesized TRGO drastically increased compared to the starting GO. Furthermore, the exfoliation process resulted in a significant decrease in the concentration of oxygen functionalities. The choice of GO exfoliation temperature was preceded by thermogravimetric analysis (TGA). TRGO was characterized using X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis.

In this study Fe-doped TiO2 (0.35 to 3.50 wt% Fe) nanotubes (NTs) were prepared as the potential photosensitizer for near-visible light driven photodynamic therapy (PDT) against cervical cancer cells (HeLa). Characterization of the prepared nanotubes by X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) confirmed the successful incorporation of Fe3+ as a dopant into the TiO2 matrix, which was mainly composed of an anatase phase, while elemental mapping using energy dispersive X-ray spectroscopy (EDX) showed homogenous distribution of the dopant ions in TiO2 for both low and high doping levels. UV-Vis studies showed that Fe doping in TiO2 increases the light absorption within the visible range, particularly in the case of 0.70 and 1.40 wt% Fe–TiO2 and provides additional energy levels within the band gap, which promotes the photo-excited charge transport towards the conduction band. Photo-cytotoxic activity of the prepared Fe-doped TiO2 NTs was investigated in vitro against cervical cancer cells (HeLa) and compared with human normal fibroblasts (GM07492). Fe-doped TiO2 NTs exhibited no or lower dark cytotoxicity than un-doped TiO2 NTs, which confirms their superior biocompatibility. Under the near-visible light irradiation (∼405 nm) Fe-doped TiO2 NTs showed higher photo-cytotoxic efficiency than un-doped TiO2 NTs, which was found to be dependent on the NTs concentration, but not on the incubation time of cells after near-visible light irradiation. The highest activity was observed for 0.70 and 1.40 wt% Fe–TiO2 NTs. Fluorescent labeling of treated HeLa cells showed distinct morphological changes, particularly in the perimitochondrial area suggesting a mitochondria-involved apoptosis of cells, but also the nuclei and cytoskeleton were subject to Fe–TiO2 NTs induced photo-damage. Apoptosis of PDT treated HeLa cells was also confirmed using ethidium homodimer (EthD-1).