Microwave-assisted hydrothermal synthesis of Ag/ZnO sub-microparticles

A fast and environmentally friendly, microwave-assisted, hydrothermal synthesis was utilized for the preparation of a Ag/ZnO hybrid system by using zinc acetate dihydrate and silver nitrate as the sources of ZU(2+) and Ag+, and hexamethylentetramine as the reducing and precipitating agent. The influence of the concentration was investigated by X-ray diffraction analysis, scanning electron microscopy and energy-dispersive analysis. It was found that the concentration has a strong effect on the morphology and proportion between the Ag and ZnO components of the prepared particulate materials. With a decreasing concentration, the morphology of the ZnO changed from twinned or single frustums to rod-like microparticles, whereas the silver morphology changed from large polygon-shaped microparticles to very small, spherical nanoparticles.internal grant of TBU in Zlin [IGA/FT/2013/014]; European Regional Development Fund (ERDF); national budget of the Czech Republic, within the Centre of Polymer Systems project [CZ.1.05/2.1.00/03.0111]; European Social Fund (ESF); national budget of the Czech Republic, within the "Advanced Theoretical and Experimental Studies of Polymer Systems" project [CZ.1.07/2.3.00/20.0104

Microstrip antenna from silver nanoparticles printed on a flexible polymer substrate

This work describes the use of inkjet printing technology to fabricate a flexible microstrip antenna. The antenna is printed on a flexible PET foil (Polyethylene terephthalate) using silver nanoparticles. Silver nanoparticles were synthetized by the solvothermal precipitation technique. The diameter of the prepared silver nanoparticles ranges from 20 to 200 nm measured with the help of the SEM analysis. In addition, the ink formulation for printing of a homogenous and electrically conductive layer was further prepared using silver nanoparticles. The printed antenna operates in two frequency bands of 2.02 GHz (-16.02 db) and 2.3 GHz (-19.33 db). The antenna is flexible and weigh is only 0.208 g and is suitable for electronic devices of a very low weight, such as wearable electronic devices. © 2017 Elsevier Ltd.Ministry of Education, Youth and Sports of the Czech Republic - National Sustainability Program NPU I [LO1504]; Operational Program Research and Development for Innovations; European Regional Development Fund (ERDF); national budget of the Czech Republic [CZ.1.05/2.1.00/19.0409

Stabilization of chitosan-based polyelectrolyte nanoparticle cargo delivery biomaterials by a multiple ionic cross-linking strategy

PolyElectrolyte Nanoparticles (PENs) obtained by layer-by-layer self-assembly of polycations/polyanions suffer from a lack of colloidal stability in physiological conditions. We report a simple innovative approach for increasing their stability by multiple ionic cross-linkers. Herein, a chitosan-based core was stabilized by polyanions such as tripolyphosphate and dextran sulfate at pHs of 3 (aPENs) and 8 (bPENs) to improve the quality of electrostatic interactions in the core and manage self-assembly of polyethyleneimine shell onto the core. The physicochemical properties of the particles were characterized by DLS, SEM, TEM, FT-IR, and TGA. TEM micrographs showed visible core/shell structures of bPENs. From particle size and polydispersity indices, the bPENs stability was salt concentration-dependent. The release profiles of PENs using nicotinic acid demonstrated sustained release in a pH-independent manner with a good fit of Korsmeyer-Peppas model. These results suggest that multiple ionic cross-linkers can be an efficient approach to increase the colloidal stability of PENs. © 2019 Elsevier LtdMinistry of Education, Youth, and Sports of the Czech RepublicMinistry of Education, Youth & Sports - Czech Republic [LO 1504

Multiband antenna made of flexible polymer substrate printed with silver nanoparticles using inkjet print technology - A feasibility study

This research paper describes a feasibility study regarding the use of inkjet printing for designing a flexible microstrip antenna. Our prototype antenna is printed, using a specially prepared ink based on silver nanoparticles with diameter ranging from 50 to 200 nm, on a plastic substrate PET (Polyethylene terephthalate). Nanoparticles and flexible PET substrate are used to achieve very advanced parameters in four frequency bands of 1.4 GHz, 3.1 GHz, 5.1 GHz and 6 GHz. These properties could be confirmed in our measurements. Multiband antennas of this type may find use in many portable devices like cell phones, where it would be possible to implement the antenna on the cover in the form of printing, thus yielding important benefits with respect to size and weight. The inkjet printing technology onto flexible polymer substrates serves another wide range of applications, namely those with high demands on flexibility, like for instance wearable technologies

Microwave-assisted particle size-controlled synthesis of ZnO nanoparticles and its application in fabrication of PLED device

ZnO nanoparticles were synthesised in diethylene glycol (DEG) with different ZnO molar precursor concentration (1 mmol, 2 mmol, 4 mmol and 8 mmol) in a microwave reactor for 15 minutes up to 250 °C. Zinc acetate dihydrate was used as the precursor for ZnO nanoparticles and oleic acid as a capping agent. It was found that different mmol precursor concentration yielded in different nanoparticle sizes. The crystallinity and particle size was analysed by XRD and the optical properties of the nanoparticles were studied by UV-Vis and PL. Oleic acid forms a layer around the ZnO nanoparticle surface. This layer helps in preparing nanocomposite solution by dispersing the ZnO nanoparticles in MEH-PPV solution. Further, the nanocomposite solution is deposited as a thin-film by spin-coating and this forms the emissive layer of the fabricated PLED device. The diode characteristics were analysed by studying the I-V and EL graphs. © Published under licence by IOP Publishing Ltd.Ministry of Education, Youth and Sports of the Czech Republic-Program NPU I [LO1504]; Operational Program Research and development for innovations; European Regional Development Fund (ERDF), national budget of the Czech Republic within the framework of project CPS - strengthening research capacity [CZ.1.05/2.1.00/19.0409, IGA/CPS/2018/007

Light-induced actuation of poly(dimethylsiloxane) filled with Graphene oxide grafted with Poly(2-(trimethylsilyloxy)ethyl Methacrylate)

This study serves to combine two approaches into one single step, to achieve a significant improvement of the light-induced actuation capabilities. Graphene oxide (GO) is an inert material, from the electrical and thermal conductivity point of view, and is incompatible with the usually-used poly(dimethylsiloxane) (PDMS) matrix. During surface-modification by surface-initiated atom transfer radical polymerization, the GO was transformed into a conducting and compatible material with the PDMS showing enormous light-induced actuation capability. The GO surface-modification with poly(2-(trimethylsilyloxy)ethyl methacrylate) (PHEMATMS) chains was confirmed by transmission electron microscopy and thermogravimetric analysis, with an on-line monitoring of gasses using FTIR. The improved compatibility was elucidated using contact angle and dielectric properties measurements. The PHEMATMS shell was investigated using gel permeation chromatography and nuclear magnetic resonance. The improved electric conductivity was measured using the four-point probe method and by Raman spectroscopy. The very important mechanical properties were elucidated using dynamic mechanical analysis, and with the help of thermo-mechanic analysis for the light-induced actuation. The excellent actuation capabilities observed, with changes in the length of around 0.8% at 10% pre-strain, are very promising from the point of view of applications. © 2018 by the authors

Effect of structure of polymers grafted from graphene oxide on the compatibility of particles with a silicone-based environment and the stimuli-responsive capabilities of their composites

This study reports the utilization of controlled radical polymerization as a tool for controlling the stimuli-responsive capabilities of graphene oxide (GO) based hybrid systems. Various polymer brushes with controlled molecular weight and narrow molecular weight distribution were grafted from the GO surface by surface-initiated atom transfer radical polymerization (SI-ATRP). The modification of GO with poly(n-butyl methacrylate) (PBMA), poly(glycidyl methacrylate) (PGMA), poly(trimethylsilyloxyethyl methacrylate) (PHEMATMS) and poly(methyl methacrylate) (PMMA) was confirmed by thermogravimetric analysis (TGA) coupled with online Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Various grafting densities of GO-based materials were investigated, and conductivity was elucidated using a four-point probe method. Raman shift and XPS were used to confirm the reduction of surface properties of the GO particles during SI-ATRP. The contact angle measurements indicated the changes in the compatibility of GOs with silicone oil, depending on the structure of the grafted polymer chains. The compatibility of the GOs with poly(dimethylsiloxane) was also investigated using steady shear rheology. The tunability of the electrorheological, as well as the photo-actuation capability, was investigated. It was shown that in addition to the modification of conductivity, the dipole moment of the pendant groups of the grafted polymer chains also plays an important role in the electrorheological (ER) performance. The compatibility of the particles with the polymer matrix, and thus proper particles dispersibility, is the most important factor for the photo-actuation efficiency. The plasticizing effect of the GO-polymer hybrid filler also has a crucial impact on the matrix stiffness and thus the ability to reversibly respond to the external light stimulation.Grant Agency of the Czech RepublicGrant Agency of the Czech Republic [16-20361Y]; Ministry of Education, Youth and Sports of the Czech Republic program NPU I [LO1504]; Research & Innovation Operational Programme - ERDF [313021T081]; project VEGAVedecka grantova agentura MSVVaS SR a SAV (VEGA) [2/0129/19]; European UnionEuropean Union (EU) [CZ.02.2.69/0.0/0.0/16_027/0008464]; Operational Program Research and Development for innovations; European Regional Development Fund (ERDF)European Union (EU); national budget of Czech Republic within project CPS -strengthening research capacity [CZ.1.05/2.1.00/19.0409]; National Science Centre, Poland [UMO-2016/23/P/ST5/02131]; European Unions' Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant [665778

Enhancing cisplatin anticancer effectivity and migrastatic potential by modulation of molecular weight of oxidized dextran carrier

The molecular weight (Mw) of dextran derivatives, such as regioselectively oxidized dicarboxydextran (DXA), is greatly influencing their faith in an organism, which could be possibly used to improve anticancer drug delivery. Here we present a modified method of sulfonation-induced chain scission allowing direct and accurate control over the Mw of DXA without increasing its polydispersity. Prepared DXA derivatives (Mw = 10–185 kDa) have been conjugated to cisplatin and the Mw of the carrier found to have a significant impact on cisplatin release rates, in vitro cytotoxicity, and migrastatic potential. Conjugates with the high-Mw DXA showed particularly increased anticancer efficacy. The best conjugate was four times more effective against malignant prostatic cell lines than free cisplatin and significantly inhibited the ovarian cancer cell migration. This was traced to the characteristics of spontaneously formed cisplatin-crosslinked DXA nanogels influenced by Mw of DXA and amount of loaded cisplatin. © 2021 Elsevier LtdMinistry of Education, Youth, and Sports of the Czech Republic -DKRVO [RP/CPS/2020/006]; Ministry of Education, Youth and Sports of the Czech RepublicMinistry of Education, Youth & Sports - Czech Republic [CZ.02.1.01/0.0/0.0/15_003/0000444, MUNI/A/1698/2020, MUNI/A/1246/2020, LM2018127]; Masaryk University in Brno [InGA/SUP/08/2020]; Czech Science FoundationGrant Agency of the Czech Republic [19-16861S]; Charles University in Prague [Progress Q26/LF1, Q27/LF1]RP/CPS/2020/006; Univerzita Karlova v Praze, UK: Q27/LF1; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: CZ.02.1.01/0.0/0.0/15_003/0000444, InGA/SUP/08/2020, MUNI/A/1246/2020, MUNI/A/1698/2020; Grantová Agentura České Republiky, GA ČR: 19-16861S, LM201812

Synthesis and characterization of poly(vinyl alcohol)-chitosan-hydroxyapatite scaffolds: a promising alternative for bone tissue regeneration

Scaffolds can be considered as one of the most promising treatments for bone tissue regeneration. Herein, blends of chitosan, poly(vinyl alcohol), and hydroxyapatite in different ratios were used to synthesize scaffolds via freeze-drying. Mechanical tests, FTIR, swelling and solubility degree, DSC, morphology, and cell viability were used as characterization techniques. Statistical significance of the experiments was determined using a two-way analysis of variance (ANOVA) with p < 0.05. Crosslinked and plasticized scaffolds absorbed five times more water than non-crosslinked and plasticized ones, which is an indicator of better hydrophilic features, as well as adequate resistance to water without detriment of the swelling potential. Indeed, the tested mechanical properties were notably higher for samples which were undergone to crosslinking and plasticized process. The presence of chitosan is determinant in pore formation and distribution which is an imperative for cell communication. Uniform pore size with diameters ranging from 142 to 519m were obtained, a range that has been described as optimal for bone tissue regeneration. Moreover, cytotoxicity was considered as negligible in the tested conditions, and viability indicates that the material might have potential as a bone regeneration system. © 2018 MDPI AG. All rights reserved.Ministry of Education, Youth and Sports of the Czech Republic-Program NPU I [LO1504]; Universidad Distrital Francisco Jose de Calda

Nanoparticle-based rifampicin delivery system development

The alkaline milieu of chronic wounds severely impairs the therapeutic effect of antibiotics, such as rifampicin; as such, the development of new drugs, or the smart delivery of existing drugs, is required. Herein, two innovative polyelectrolyte nanoparticles (PENs), composed of an amphiphilic chitosan core and a polycationic shell, were synthesized at alkaline pH, and in vitro performances were assessed by H-1 NMR, elemental analysis, FT-IR, XRD, DSC, DLS, SEM, TEM, UV/Vis spectrophotometry, and HPLC. According to the results, the nanostructures exhibited different morphologies but similar physicochemical properties and release profiles. It was also hypothesized that the simultaneous use of the nanosystem and an antioxidant could be therapeutically beneficial. Therefore, the simultaneous effects of ascorbic acid and PENs were evaluated on the release profile and degradation of rifampicin, in which the results confirmed their synergistic protective effect at pH 8.5, as opposed to pH 7.4. Overall, this study highlighted the benefits of nanoparticulate development in the presence of antioxidants, at alkaline pH, as an efficient approach for decreasing rifampicin degradation.Ministry of Education, Youth and Sport of the Czech Republic-DKRVO [RP/CPS/2020/005