Remodelling of collagen fibers has been described during every phase of cancer genesis and progression. Changes in morphology and organization of collagen fibers contribute to the formation of ...microenvironment that favors cancer progression and development of metastasis. However, there are only few data about remodelling of collagen fibers in healthy looking mucosa distant from the cancer. Using SHG imaging, electron microscopy and specialized softwares (CT-FIRE, CurveAlign and FiberFit), we objectively visualized and quantified changes in morphology and organization of collagen fibers and investigated possible causes of collagen remodelling (change in syntheses, degradation and collagen cross-linking) in the colon mucosa 10 cm and 20 cm away from the cancer in comparison with healthy mucosa. We showed that in the lamina propria this far from the colon cancer, there were changes in collagen architecture (width, straightness, alignment of collagen fibers and collagen molecules inside fibers), increased representation of myofibroblasts and increase expression of collagen-remodelling enzymes (LOX and MMP2). Thus, the changes in organization of collagen fibers, which were already described in the cancer microenvironment, also exist in the mucosa far from the cancer, but smaller in magnitude.
Herein, the ability of gamma irradiation to enhance the photoluminescence properties of graphene quantum dots (GQDs) was investigated. Different doses of γ-irradiation were used on GQDs to examine ...the way in which their structure and optical properties can be affected. The photoluminescence quantum yield was increased six times for the GQDs irradiated with high doses compared to the nonirradiated material. Both photoluminescence lifetime and values of optical band gap were increased with the dose of applied gamma irradiation. In addition, the exploitation of the gamma-irradiated GQDs as photosensitizers was examined by monitoring the production of singlet oxygen under UV illumination. The main outcome was that the GQDs irradiated at lower doses act as better photoproducers than the ones irradiated at higher doses. These results corroborate that the structural changes caused by gamma irradiation have a direct impact on GQD ability to produce singlet oxygen and their photostability under prolonged UV illumination. This makes low-dose irradiated GQDs promising candidates for photodynamic therapy.
The rise of innovation in the electrical industry is driven by the controlled design of new materials. The hybrid materials based on magnetite/nanocellulose are highly interesting due to their ...various applications in medicine, ecology, catalysis and electronics. In this study, the structure and morphology of nanocellulose/magnetite hybrid nanomaterials were investigated. The effect of nanocellulose loading on the crystal structure of synthesized composites was investigated by XRD and FTIR methods. The presented study reveals that the interaction between the cellulose and magnetic nanoparticles depends on the nanocellulose content. Further, a transition from cellulose II to cellulose I allomorph is observed. SEM and EDS are employed to determine the variation in morphology with changes in component concentrations. By the calculation of magnetic interactions between adjacent Fe3+ and Fe2+ ions within composites, it is determined that ferromagnetic coupling predominates.
Freeze drying was compared with spray drying regarding feasibility to process wild thyme drugs in order to obtain dry formulations at laboratory scale starting from liquid extracts produced by ...different extraction methods: maceration and heat-, ultrasound-, and microwave-assisted extractions. Higher total powder yield (based on the dry weight prior to extraction) was achieved by freeze than spray drying and lower loss of total polyphenol content (TPC) and total flavonoid content (TFC) due to the drying process. Gelatin as a coating agent (5% w/w) provided better TPC recovery by 70% in case of lyophilization and higher total powder yield in case of spray drying by diminishing material deposition on the wall of the drying chamber. The resulting gelatin-free and gelatin-containing powders carried polyphenols in amount ~190 and 53–75 mg gallic acid equivalents GAE/g of powder, respectively. Microwave-assisted extract formulation was distinguished from the others by a higher content of polyphenols, proteins and sugars, higher bulk density and lower solubility. The type of the drying process mainly affected the position of the gelatin-derived -OH and amide bands in FTIR spectra. Spray-dried formulations compared to freeze-dried expressed higher thermal stability as confirmed by differential scanning calorimetry analysis and a higher diffusion coefficient; the last feature can be associated with the lower specific surface area of irregularly shaped freeze-dried particles (151–223 µm) compared to small microspheres (~8 µm) in spray-dried powder.
Titanium dioxide is a photocatalyst, known not only for its ability to oxidize organic contaminants, but also for its antimicrobial properties. In this article, significant enhancement of the ...antimicrobial activity of TiO2 (up to 32 times) was demonstrated after its activation by ball milling. The antimicrobial activity was analyzed for one fungal and 13 bacterial ATCC strains using the microdilution method and recording the minimum inhibitory concentration (MIC) values. In order to further investigate the correlation between the mechanical activation of TiO2 and its antimicrobial activity, the structure, morphology and phase composition of the material were studied by means of Electron Microscopy, X‐ray diffraction and nitrogen adsorption‐desorption measurements. UV‐Vis diffuse reflectance spectra were recorded and the Kubelka‐Munk function was applied to convert reflectance into the equivalent band gap energy (Eg) and, consequently, to investigate changes in the Eg value. X‐ray photoelectron spectroscopy was used to analyze the influence of mechanical activation on the Ti 2p and O 1s spectra. The presented results are expected to enable the development of more sustainable and effective advanced TiO2‐based materials with antimicrobial properties that could be used in numerous green technology applications.
Na0.25K0.25Bi0.5TiO3 (NKBT) perovskite particles are synthesized by solid-state method and used as a filler for polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) co-polymer. X-ray diffraction ...analysis of NKBT powders shows that the particles have a rhombohedral perovskite crystal structure (R3c symmetry). Raman spectroscopy reveals that the co-polymer crystallizes predominantly into the mixture of polar β- and γ-crystals, while there is also a contribution of the non-polar α-crystal phase. The introduction of the NKBT into the PVDF-HFP results with an increase in effective dielectric permittivity and this effect depends on the inorganic content in the composite. The most interesting result of the present study is that the introduction of NKBT particles induces the appearance of an additional transition peak in the dielectric spectra of the co-polymer matrix. At the fixed frequency of ~2 kHz, the observed process appears at ~10 °C (about 45° above the glass transition temperature) and its magnitude strongly depends on the amount of the NKBT in the composite. Dielectric spectroscopy measurements of the composites are carried out in the wide range of frequencies (from 0.1 Hz to 1 MHz) and temperatures (from −100 to 100 °C). They reveal that the novel process can be clearly distinguished in the frequency range between 160 Hz and ~50 kHz.
•Na0.25K0.25Bi0.5TiO3 (NKBT) perovskite particles are synthesized by solid state method.•PVDF-HFP/NKBT composite films were prepared by solution mixing.•NKBT particles induce an increase in effective dielectric permittivity of the films.•An additional transition peak was observed in the dielectric spectra of the composite film.•The magnitude of the novel transition depends on the NKBT content.
This article presents the results of the compositional, structural and morphological study of geopolymers synthesized from metakaolin and an alkali activator. The study involved the investigation of ...the structural and chemical properties of the geopolymer, in addition to thermally treated geopolymers up to 600 and 900°C. The precursor of the geopolymer, and the geopolymer samples before and after the thermal treatment, were investigated by Fourier transformation infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and SEM analysis. The corrected average value of the ratio of silicon and aluminum in the geopolymer samples (SiGP:Al) is about 1.46, which suggests that the obtained geopolymer samples represent a mixture of roughly equal amounts of sialate and sialate-siloxo units. Annealing the geopolymer samples at 600°C decreases the amount of Si-ONa bonds and induces the cross-linking of polymer changes. At the same time, other sodium containing alumino-silicate phases are created. The thermal treatment at 900°C leads to a considerable reduction of oxygen and particularly sodium, followed by significant morphological changes i.e. formation of a complex porous structure. Additionally, a new semicrystaline phase appears. Both XRD and XPS results imply that this new phase may be nepheline and it is plausible that this phase begins to nucleate at temperatures below 900°C.
•Esterification of nanocellulose with fatty acids by either direct method or via linker was done.•The vacuum and supercritical CO2 drying (SCD) of functionalized NC (m-NC) was performed.•The SCD ...drying improved thermal stability, surface properties and morphology of m-NC.•The vinyl reactivity at m-NC surface contribute to reinforcement in polyester based composites.
The influence of modification and vacuum/supercritical CO2 (scCO2) drying methods on the surface properties, morphology and thermal stability of cellulose nanocrystals (NC) was presented in this study. Introduction of reactive vinyl groups on NC surface was performed by either direct esterification with oleic acid, linseed or sunflower oil fatty acids; or by amidation of maleic acid/ethylene diamine with methyl ester of fatty acid. Obtained modified NC (m-NC) were characterized using FTIR and Raman spectroscopy; and by determination of acid, iodine and ester values. Structural analysis of m-NC showed varieties of forms, from spongy to nanostructural non-uniform layered morphology with observable agglomeration, which confirmed morphology dependence on modification/processing methods Thermogravimetry-MS spectrometry showed different thermal stability and degradation pathways of NC/m-NC. Incorporation of 1 wt% of reactive m-NC in unsaturated polyester lead to high performance nanocomposites and contributed to increase of stress at break in the range from 76 to 93%.
Due to controversial reports concerning antibacterial activity of different graphene based materials it is very important to investigate their antibacterial action on a wide range of Gram-positive ...and Gram-negative bacteria. In this paper we have investigated the structure induced phototoxic antibacterial activity of four types of graphene based materials: graphene oxide (GO), graphene quantum dots (GQDs), carbon quantum dots (CQDs) and nitrogen doped carbon quantum dots (N-CQDs). Antibacterial activity was tested on 19 types of bacteria. It is found that nanometer-size CQDs and N-CQDs are the most potent agents whereas micrometer-size GO has very poor antibacterial activity. Electron paramagnetic resonance measurements confirmed photodynamic production of singlet oxygen for all types of used quantum dots. Detailed analysis has shown that N-CQDs are an excellent photodynamic antibacterial agent for treatment of bacterial infections induced by
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