Surfactant-free silver nanofluids as liquid systems with neuromorphic potential
Nikitin, D.; Biliak, K.; Lemke, J.; Protsak, M.; Pleskunov, P.; Tosca, M.; Ali-Ogly, S.; Červenková, V.; Adejube, B.; Bajtošová, L.; Černochová, Zulfiya; Prokeš, J.; Křivka, I.; Biederman, H.; Faupel, F.; Vahl, A.; Choukourov, A.
2024 - anglický Neuromorphic engineering is a rapidly developing branch of science that aims to implement the unique attributes of biological neural networks in artificial devices. Most neuromorphic devices are based on the resistive switching effect, which involves changing the device’s conductivity in response to an external electric field. For instance, percolating nanoparticle (NP) networks produced by gas aggregation cluster sources (GAS) show collective spiking behavior in conductivity reminiscent of brain-like dynamics. Nevertheless, the problem of dynamic spatial reconfiguration in solid-state neuromorphic systems remains unsolved. Herein, novel nanofluids with resistive switching properties are proposed as neuromorphic media. They are produced by depositing silver NPs from GAS into vacuum-compatible liquids (paraffin, silicon oil, and PEG) without the use of surfactants or other chemicals. When the electric field is applied between two electrodes, the migration of NPs toward biased electrode is detected in all liquids. The electrophoretic nature of the NP movement was proved by means of ζ-potential measurements. Such movement led to the self-assembly of NPs in conductive paths connecting the electrodes and, as a result, to resistive switching. The electrical response was strongly dependent on the dielectric constant of the base liquid. The Ag-PEG nanofluid demonstrated the best switching performance reproducible during several tens of current-voltage cycles. The growth of flexible and reconfigurable conductive filaments in nanofluids makes them suitable media for potential realization of 3D neural networks. Klíčová slova: nanofluid; gas aggregation cluster source; ζ-potential, electrophoresis Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR. Surfactant-free silver nanofluids as liquid systems with neuromorphic potential

Neuromorphic engineering is a rapidly developing branch of science that aims to implement the unique attributes of biological neural networks in artificial devices. Most neuromorphic devices are based ...

Nikitin, D.; Biliak, K.; Lemke, J.; Protsak, M.; Pleskunov, P.; Tosca, M.; Ali-Ogly, S.; Červenková, V.; Adejube, B.; Bajtošová, L.; Černochová, Zulfiya; Prokeš, J.; Křivka, I.; Biederman, H.; Faupel, F.; Vahl, A.; Choukourov, A.
Ústav makromolekulární chemie, 2024

Temoporfin-conjugated upconversion nanoparticles for NIR-induced photodynamic therapy of pancreatic cancer
Shapoval, Oleksandr; Větvička, D.; Kabešová, M.; Engstová, Hana; Horák, Daniel
2024 - anglický Photodynamic therapy (PDT), a clinically approved cancer treatment strategy, has the potential to cure pancreatic cancer with minimal side effects. PDT primarily uses visible wavelengths to directly activate hydrophobic photosensitizers, which may be insufficient for deep-seated cancer cells in clinical practice due to poor penetration. Upconversion nanoparticles (UCNPs) serve as an indirect excitation source to activate photosensitizers (PSs) in the NIR region, overcoming the limitations of molecular PSs such as hydrophobicity, non-specificity, and excitation in the UV/Vis region. Here, monodisperse upconversion NaYF4:Yb3+, Er3+, Fe2+ nanoparticles (UCNPs) have been surface-engineered with poly(methyl vinyl ether-alt-maleic acid) (PMVEMA) and temoporfin (mTHPC), a clinically used PDT prodrug, for near-infrared (NIR) light-triggered PDT of pancreatic cancer. The incorporation of Fe2+ ions into the particles increased the fluorescence intensity in the red region matching the activation wavelength of mTHPC. Covalent binding of mTHPC to the surface of UCNP@PMVEMA particles provided colloidally stable conjugates enabling generation of singlet oxygen. In vitro cytotoxicity and photodynamic activity of the particles were evaluated using INS-1E rat insulinoma and Capan-2 and PANC-01 human pancreatic adenocarcinoma cell lines. The PDT efficacy of UCNP@PMVEMA-mTHPC conjugates after irradiation with 980 nm NIR light was tested in vivo in a pilot study on Capan-2 human pancreatic adenocarcinoma growing subcutaneously in athymic nude mice. The intratumoral administration of the nanoconjugates significantly hindered tumor growth and demonstrated promising PDT efficacy against human pancreatic cancer. Klíčová slova: photodynamic therapy; temoporfin; upconversion nanoparticles Plné texty jsou dostupné v digitálním repozitáři Akademie Věd. Temoporfin-conjugated upconversion nanoparticles for NIR-induced photodynamic therapy of pancreatic cancer

Photodynamic therapy (PDT), a clinically approved cancer treatment strategy, has the potential to cure pancreatic cancer with minimal side effects. PDT primarily uses visible wavelengths to directly ...

Shapoval, Oleksandr; Větvička, D.; Kabešová, M.; Engstová, Hana; Horák, Daniel
Ústav makromolekulární chemie, 2024

Degradation of polycaprolactone electrospun materials - methods of analysis
Havlíčková, K.; Řezanka, M.; Kobera, Libor; Kuželová Košťáková, E.; Lukáš, D.; Jenčová, V.
2021 - anglický Biodegradable electrospun materials are widely used for medical application. Polycaprolatone is polymer suitable for electrospinning technology and is very often used to create nanofibrous scaffolds for tissue engineering. The time to disintegration or biodegradation of such materials is very important here. However, testing is not entirely easy. It is not possible to create exactly body-like conditions in vitro. Moreover, it is not easy to find suitable analytical methods that would show exactly what happens in the nanofibrous polycaprolactone electrospun samples at certain stages of degradation, ie how the internal structure of decaying nanofibers changes. This paper describes the traditional use of methods for testing polycaprolatone nanofibers by enzymatically catalysed degradation. Morphological changes are studied using scanning electron microscope images. However, it also offers a non-traditional analysis of polycaprolactone electrospun materials using the ssNMR method. Klíčová slova: electrospinning; nanofibers; enzymatic degradation Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR. Degradation of polycaprolactone electrospun materials - methods of analysis

Biodegradable electrospun materials are widely used for medical application. Polycaprolatone is polymer suitable for electrospinning technology and is very often used to create nanofibrous scaffolds ...

Havlíčková, K.; Řezanka, M.; Kobera, Libor; Kuželová Košťáková, E.; Lukáš, D.; Jenčová, V.
Ústav makromolekulární chemie, 2021

Anticorrosive properties of silicotungstic acid and phosphotungstic heteropolyacid in the paint films
Nechvílová, K.; Kalendová, A.; Stejskal, Jaroslav
2016 - anglický The aim of this work was to provide an initial characterisation of heteropolyacids and examine their behaviour and properties as pigments in paints using different concentrations of the pigment and filler. Solvent-based epoxy-ester resin served as the binder. The paints were applied to steel and glass panels for mechanical and corrosion resistance testing. The organic coatings were exposed to a corrosive atmosphere with NaCl. This test was completed with electrochemical measurement. The parameters examined included the paint film's mechanical and anticorrosion efficiency. The environments in which the new coatings are most efficient were also sought. Klíčová slova: heteropolyacids; epoxy-ester resin; organic coatings Dokument je dostupný na externích webových stránkách. Anticorrosive properties of silicotungstic acid and phosphotungstic heteropolyacid in the paint films

The aim of this work was to provide an initial characterisation of heteropolyacids and examine their behaviour and properties as pigments in paints using different concentrations of the pigment and ...

Nechvílová, K.; Kalendová, A.; Stejskal, Jaroslav
Ústav makromolekulární chemie, 2016

The influence of compression pressure on transport properties of polypyrrole nanotubes
Alekseeva, E.; Prokeš, J.; Bober, Patrycja; Stejskal, Jaroslav
2015 - anglický Klíčová slova: conducting polymer; polypyrrole nanotubes Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR. The influence of compression pressure on transport properties of polypyrrole nanotubes

Alekseeva, E.; Prokeš, J.; Bober, Patrycja; Stejskal, Jaroslav
Ústav makromolekulární chemie, 2015

Ultrathin nanofibrous membranes with enhanced properties for transplantation of retinal pigment epithelial cells
Studenovská, Hana; Popelka, Štěpán; Abelová, Lucie; Riedel, Tomáš; Studený, P.; Straňák, Z.; Klíma, Jiří; Ardan, Taras; Dvořánková, B.; Rypáček, František
2015 - anglický Klíčová slova: retinal tissue engineering; nanofibrous membrane; fibrin coating Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR. Ultrathin nanofibrous membranes with enhanced properties for transplantation of retinal pigment epithelial cells

Studenovská, Hana; Popelka, Štěpán; Abelová, Lucie; Riedel, Tomáš; Studený, P.; Straňák, Z.; Klíma, Jiří; Ardan, Taras; Dvořánková, B.; Rypáček, František
Ústav makromolekulární chemie, 2015

Polymers based on chemically modified starch
Horák, Pavel; Kruliš, Zdeněk; Šárka, E.; Kobera, Libor
2014 - anglický In our research, we are developing materials based on chemical modified wheat starch ant its derivatives. The starch is esterified with various acids or acid anhydrides, e.g. acetic or propionic acid. Main goal of this work is to determine the degree of substitution, which has significant relevance in study of modified saccharides. it was done using three different techniques - acid-base titration, elemental analysis and nuclear magnetic resonance spectroscopy. Klíčová slova: starch; chemical modification; degree of substitution Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR. Polymers based on chemically modified starch

In our research, we are developing materials based on chemical modified wheat starch ant its derivatives. The starch is esterified with various acids or acid anhydrides, e.g. acetic or propionic acid. ...

Horák, Pavel; Kruliš, Zdeněk; Šárka, E.; Kobera, Libor
Ústav makromolekulární chemie, 2014

A study of silver nanoparticle behavior in liquid media for ecotoxicity tests
Opršal, J.; Pouzar, M.; Knotek, P.; Šlouf, Miroslav; Pavlova, Ewa
2012 - anglický The up to date increasing number of nanotechnology applications is linked with a serious danger of environmental pollution by nanomaterials. Consequently, the ecotoxicity testing of nanomaterials becomes an essential part of nanotechnology development. Classical ecotoxicity tests suffer with a number of complications when used for nanomaterials. In the case of aquatic toxicity tests, the nanoparticle agglomeration in the liquid media is a fundamental problem. The aim of this work is to evaluate the influence of important physico-chemical parameters (nanoparticle concentration and illumination conditions) on an agglomeration of 40 nm silver nanoparticles (AgNPs) in a liquid media prescribed for fish eco-toxicity test by the OECD 203 guideline (Medium 203). Klíčová slova: nanoparticles; lequid media; ecotoxicity Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR. A study of silver nanoparticle behavior in liquid media for ecotoxicity tests

The up to date increasing number of nanotechnology applications is linked with a serious danger of environmental pollution by nanomaterials. Consequently, the ecotoxicity testing of nanomaterials ...

Opršal, J.; Pouzar, M.; Knotek, P.; Šlouf, Miroslav; Pavlova, Ewa
Ústav makromolekulární chemie, 2012

Electrical conductivity of polyaniline-silver nanocomposites
Varga, M.; Prokeš, J.; Bober, Patrycja; Stejskal, Jaroslav
2012 - anglický Klíčová slova: polyaniline; composites; silver Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR. Electrical conductivity of polyaniline-silver nanocomposites

Varga, M.; Prokeš, J.; Bober, Patrycja; Stejskal, Jaroslav
Ústav makromolekulární chemie, 2012

The use of real time PCR method for evaluation of magnetic microspheres
Trachtová, Š.; Rittich, B.; Horák, Daniel; Španová, A.
2012 - anglický The real-time quantitative PCR (qPCR) was used for the evaluation of non-porous HEMA-based magnetic microspheres on the PCR course (PCR sensitivity). It was shown that 1-10 mu l microsphere suspensions (2 mg/ml) in PCR mixtures do not interfere in the PCR. It can be assumed that the magnetic nuclei were covered with polymer layer. Klíčová slova: magnetic microspheres; real time PCR Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR. The use of real time PCR method for evaluation of magnetic microspheres

The real-time quantitative PCR (qPCR) was used for the evaluation of non-porous HEMA-based magnetic microspheres on the PCR course (PCR sensitivity). It was shown that 1-10 mu l microsphere ...

Trachtová, Š.; Rittich, B.; Horák, Daniel; Španová, A.
Ústav makromolekulární chemie, 2012