Increasing the effectivity of the antimicrobial surface of carbon quantum dots-based nanocomposite by atmospheric pressure plasma

Preventing nosocomial infections is one of the most significant challenges in modern medicine. The disinfection of medical facilities and medical devices is crucial in order to prevent the uncontrolled spread of bacteria and viruses. Cost-effective, eco-friendly and fast-acting antibacterial coatings are being developed as the prevention of bacteria and viruses' multiplication on various surfaces. One of the possibilities to create such antimicrobial coatings can rely on a photoactive material, that produces singlet oxygen. However, a remote production of the singlet oxygen and disinfection of the desired surface is a time-consuming process. Hence, a coating material that would autonomously produce singlet oxygen employing ambient light will have a significant impact on the shortening of the disinfection time; leading into an increased number of patients that can be cured in one facility. In this work, an ultra-fast and eco-friendly method for decreasing the disinfection time of the photoactive surface is presented. The atmospheric pressure plasma surface treatment on the hydrophobic carbon quantum dots-polydimethylsiloxane nanocomposite is employed. The plasma-treated samples exhibited improved antibacterial properties compared to non-plasma treated samples, with the best results obtained after only 30 seconds of plasma treatment. The short duration and the scalability potential of the here described method open new possibilities of how to improve the already existing antibacterial coatings. © 2020 Elsevier GmbHResearch & Innovation Operational Programme - ERDF; Czech Science FoundationGrant Agency of the Czech Republic [19-16861S]; project Buildingup Centre for Advanced Materials Application of the Slovak Academy of Sciences [313021T081]; [VEGA 2/0051/20]; [APVV-15-0641

Adsorption of an active molecule on the surface of halloysite for controlled release application: Interaction, orientation, consequences

The goal of the study was to check the possible use of halloysite (Hal) nanotubes as a controlled release natural antioxidant device with quercetin as the active component. The mineral was thoroughly characterized by various techniques including the determination of particle and tube morphology, specific surface area, pore size and volume, and surface energy. The high surface energy of Hal predicted strong adsorption of active molecules on its surface and consequently difficult release. FTIR spectroscopy confirmed the existence of strong interactions, energetically heterogeneous Hal surface and multilayer coverage at large loadings. FTIR and XRD experiments proved the complete lack of intercalation and showed that below 3.5 wt% quercetin loading, most of the molecules are located within the Hal tubes. Molecular modeling indicated the parallel orientation of quercetin molecules with the surface. Critical concentrations derived from various measurements agreed well with each other further confirming that up to about 4.0 wt% loading, quercetin is bonded very strongly to the Hal surface. As a consequence, the dissolution of active molecules is very difficult or impossible, especially into apolar media; thus, neither stabilization nor controlled release effect can be expected below that concentration

Effect of plasma treatment on the release kinetics of a chemotherapy drug from biodegradable polyester films and polyester urethane films

Investigation was made into the effect of plasma treatment on the release kinetics of the drug Temozolomide (TMZ) from thin, biodegradable polyester films, comprising polylactic acid (PLA) and polyester urethane. The authors utilized two systems to achieve this, the first being diffuse coplanar surface barrier discharge, applying air as the gaseous medium, while the other involved capacitively coupled radio frequency discharge plasma under an argon atmosphere with hexamethyldisiloxane. Results showed that both forms of plasma treatment positively reduced the undesirable burst effect and benefited the release rate of TMZ. The hydrolytic degradability of the materials was slightly enhanced following hydrophilization, whereas the same diminished after hydrophobization had taken place. This was especially true for PLA due to modification of its wettability. © 2017 Taylor & Francis.02/0199/14, VEGA, Vedecká Grantová Agentúra MŠVVaŠ SR a SAV; APVV-14-0518, APVV, Agentúra na Podporu Výskumu a Vývoja; QJ1310254, MZe, Ministerstvo Zemědělství; SAV, Slovenská Akadémia Vied; 15-08287Y, GACR, Grantová Agentura České Republiky; CZ.1.05/2.1.00/19.0409; LO1504Czech Science Foundation [15-08287Y]; Ministry of Agriculture of the Czech Republic [QJ1310254]; Ministry of Education, Youth and Sports of the Czech Republic [LO1504, CZ.1.05/2.1.00/19.0409]; Ministry of Education, Science, Research and Sports of the Slovak Republic; Slovak Academy of Sciences, as a part of the "VEGA" project [02/0199/14]; Slovak Research and Development Agency [APVV-14-0518

Polyethylene Glycol-Modified Poly(Styrene-co-Ethylene/Butylene-co-Styrene)/Carbon Nanotubes Composite for Humidity Sensing

Polymeric composites of the linear triblock copolymer poly(styrene-co-ethylene/butylene-co-styrene) grafted with maleic anhydride units (SEBS-MA) or MA modified by hydrophilic polyethylene glycol (PEG) and containing various amounts of multiwall carbon nanotubes (MWCNTs) as conducting filler—were prepared by solvent casting. The MWCNT surface was modified by a non-covalent approach with a pyrene-based surfactant to achieve a homogeneous dispersion of the conducting filler within the polymeric matrix. The dispersion of the unmodified and surfactant-modified MWCNTs within the elastomeric SEBS-MA and SEBS-MA-PEG matrices was characterized by studying the morphology by TEM and SAXS. Dynamical mechanical analysis was used to evaluate the interaction between the MWCNTs and copolymer matrix. The electrical conductivity of the prepared composites was measured by dielectric relaxation spectroscopy, and the percolation threshold was calculated. The prepared elastomeric composites were characterized and studied as humidity sensor. Our results demonstrated that at MWCNTs concentration slightly above the percolation threshold could result in large signal changes. In our system, good results were obtained for MWCNT loading of 2 wt% and an ~0.1 mm thin composite film. The thickness of the tested elastomeric composites and the source current appear to be very important factors that influence the sensing performance

Electrochemical performance of composite electrodes based on rGO, Mn/Cu metal-organic frameworks, and PANI

Benzendicarboxylic acid (BDC)-based metal-organic frameworks (MOFs) have been widely utilized in various applications, including supercapacitor electrode materials. Manganese and copper have solid diamond frames formed with BDC linkers among transition metals chosen for MOF formation. They have shown the possibility to enlarge capacitance at different combinations of MOFs and polyaniline (PANI). Herein, reduced graphene oxide (rGO) was used as the matrix to fabricate electrochemical double-layer SCs. PANI and Mn/Cu-MOF's effect on the properties of electrode materials was investigated through electrochemical analysis. As a result, the highest specific capacitance of about 276 F/g at a current density of 0.5 A/g was obtained for rGO/Cu-MOF@PANI composite.M-era.Net 2019 call project "LiBASED Li-ion BAttery-SupErcapacitor Hybrid Device"; Technology Agency of the Czech Republic EPSILON Programme [TH71020006]; Ministry of Education, Youth & Sports of the Czech Republic-DKRVO [RP/CPS/2020/005]; Tomas Bata University in Zli

Gas-phase epoxidation of propylene over iron-containing catalysts: the effect of iron incorporation in the support matrix

The gas-phase epoxidation of propylene using iron as a catalytically active metal has been studied. The XRD-amorphous silica nanopowder was found to host active as well as redox-silent iron species, using nitrous oxide as an oxidizing agent. The presence of iron oxide nanoparticles was proven in the most active catalysts, indicating that the epoxidation proceeds over nanoparticles rather than over isolated iron atoms. A combination of XPS, TEM and voltammetric techniques elucidated the mechanism of the formation of catalytically active forms of iron oxide, distinguishing selective forms from unselective and inactive ones in the epoxidation reaction. Transition response experiments showed a good correlation between epoxidation activity, N2O decomposition and electrochemical specification of iron oxides.Web of Science482673266

Mechanical, sorption and adhesive properties of composites based on low density polyethylene filled with date palm wood powder

Low density polyethylene (LDPE) was blended with date palm wood powder (DPW) to prepare composites with concentrations of filler ranging from 10 to 70. wt.%. The Youn?s modulus of the composites significantly increased with an increase in the filler content in the entire concentration range. The maximum value of 1933. MPa for the composite filled with 70. wt.% of the filler is approximately 13 times higher than that for the neat LDPE.The presence of the filler improved the flexural strength, which was represented by the flexural stress at peak. The flexural strength of 17.8. MPa for the composite filled with 70. wt.% of the filler was two-times greater than that for the neat LDPE. The water absorption test revealed that the composites had a strong tendency to absorb water, which was dependent on the filler content. The experimental data were compared with several theoretical models.Scopu