2021, Chen, Jiang, Dai, Sheng, Liu, Luying, Maitz, Manfred F., Liao, Yuzhen, Cui, Jiawei, Zhao, Ansha, Yang, Ping, Huang, Nan, Wang, Yunbing

Titanium dioxide (TiO2) has a long history of application in blood contact materials, but it often suffers from insufficient anticoagulant properties. Recently, we have revealed the photocatalytic effect of TiO2 also induces anticoagulant properties. However, for long-term vascular implant devices such as vascular stents, besides anticoagulation, also anti-inflammatory, anti-hyperplastic properties, and the ability to support endothelial repair, are desired. To meet these requirements, here, we immobilized silver nanoparticles (AgNPs) on the surface of TiO2 nanotubes (TiO2-NTs) to obtain a composite material with enhanced photo-induced anticoagulant property and improvement of the other requested properties. The photo-functionalized TiO2-NTs showed protein-fouling resistance, causing the anticoagulant property and the ability to suppress cell adhesion. The immobilized AgNPs increased the photocatalytic activity of TiO2-NTs to enhances its photo-induced anticoagulant property. The AgNP density was optimized to endow the TiO2-NTs with anti-inflammatory property, a strong inhibitory effect on smooth muscle cells (SMCs), and low toxicity to endothelial cells (ECs). The in vivo test indicated that the photofunctionalized composite material achieved outstanding biocompatibility in vasculature via the synergy of photo-functionalized TiO2-NTs and the multifunctional AgNPs, and therefore has enormous potential in the field of cardiovascular implant devices. Our research could be a useful reference for further designing of multifunctional TiO2 materials with high vascular biocompatibility.

2022, Au-Yeung, Kwan Ho, Kühne, Tim, Aiboudi, Oumaima, Sarkar, Suchetana, Guskova, Olga, Ryndyk, Dmitry A., Heine, Thomas, Lissel, Franziska, Moresco, Francesca

Dihydroazulene/vinylheptafulvene pairs are known as molecular dipole switches that undergo a ring-opening/-closure reaction by UV irradiation or thermal excitation. Herein, we show that the ring-closure reaction of a single vinylheptafulvene adsorbed on the Au(111) surface can be induced by voltage pulses from the tip of a scanning tunneling microscope. This cyclization is accompanied by the elimination of HCN, as confirmed by simulations. When inducing lateral movements by applying voltage pulses with the STM tip, we observe that the response of the single molecules changes with the ring closing reaction. This behaviour is discussed by comparing the dipole moment and the charge distribution of the open and closed forms on the surface.

2020, Prehn, Franziska, Timmermann, Eric, Kettlitz, Manfred, Schaufler, Katharina, Günther, Sebastian, Hahn, Veronika

Airborne bacteria are a general problem in medical or health care facilities with a high risk for nosocomial infections. Rooms with a continuous airflow, such as operation theaters, are of particular importance due to a possible dissemination and circulation of pathogens including multidrug-resistant microorganisms. In this regard, a cold atmospheric-pressure plasma (CAP) may be a possibility to support usual disinfection procedures due to its decontaminating properties. The aim of this study was to determine the antimicrobial efficacy of a plasma decontamination module that included a dielectric barrier discharge for plasma generation. Experimental parameters such as an airflow velocity of 4.5 m/s and microbial contaminations of approximately 6,000 colony-forming units (cfu)/m3 were used to simulate practical conditions of a ventilation system in an operating theater. The apathogenic microorganism Escherichia coli K12 DSM 11250/NCTC 10538 and the multidrug-resistant strains E. coli 21181 and 21182 (isolated from patients) were tested to determine the antimicrobial efficacy. In summary, the number of cfu was reduced by 31–89% for the tested E. coli strains, whereby E. coli K12 was the most susceptible strain toward inactivation by the designed plasma module. A possible correlation between the number or kind of resistances and susceptibility against plasma was discussed. The inactivation of microorganisms was affected by plasma intensity and size of the plasma treatment area. In addition, the differences of the antimicrobial efficacies caused through the nebulization of microorganisms in front (upstream) or behind (downstream) the plasma source were compared. The presence of ionic wind had no influence on the reduction of the number of cfu for E. coli K12, as the airflow velocity was too high for a successful precipitation, which would be a prerequisite for an increased antimicrobial efficacy. The inactivation of the tested microorganisms confirms the potential of CAP for the improvement of air quality. The scale-up of this model system may provide a novel tool for an effective air cleaning process.

2012, Glampedaki, P., Calvimontes, A., Dutschk, V., Warmoeskerken, M.M.C.G.

A new approach to functionalize the surface of polyester textiles is described in this study. Functionalization was achieved by incorporating pH/temperature-responsive polyelectrolyte microgels into the textile surface layer using UV irradiation. The aim of functionalization was to regulate polyester wettability according to ambient conditions by imparting stimuli-responsiveness from the microgel to the textile itself. Microgels consisted of pH/thermo-responsive microparticles of poly(N-isopropylacrylamide- co-acrylic acid) either alone or complexed with the pH-responsive natural polysaccharide chitosan. Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy, ζ-potential measurements, and topographical analysis were used for surface characterization. Wettability of polyester textiles was assessed by dynamic wetting, water vapor transfer, and moisture regain measurements. One of the main findings showed that the polyester surface was rendered pH-responsive, both in acidic and alkaline pH region, owing to the microgel incorporation. With a marked relaxation in their structure and an increase in their microporosity, the functionalized textiles exhibited higher water vapor transfer rates both at 20 and 40 °C, and 65% relative humidity compared with the reference polyester. Also, at 40 °C, i.e., above the microgel Lower Critical Solution Temperature, the functionalized polyester textiles had lower moisture regains than the reference. Finally, the type of the incorporated microgel affected significantly the polyester total absorption times, with an up to 300% increase in one case and an up to 80% decrease in another case. These findings are promising for the development of functional textile materials with possible applications in biotechnology, technical, and protective clothing.