Objective comparison of methods to decode anomalous diffusion

Deviations from Brownian motion leading to anomalous diffusion are found in transport dynamics from quantum physics to life sciences. The characterization of anomalous diffusion from the measurement of an individual trajectory is a challenging task, which traditionally relies on calculating the trajectory mean squared displacement. However, this approach breaks down for cases of practical interest, e.g., short or noisy trajectories, heterogeneous behaviour, or non-ergodic processes. Recently, several new approaches have been proposed, mostly building on the ongoing machine-learning revolution. To perform an objective comparison of methods, we gathered the community and organized an open competition, the Anomalous Diffusion challenge (AnDi). Participating teams applied their algorithms to a commonly-defined dataset including diverse conditions. Although no single method performed best across all scenarios, machine-learning-based approaches achieved superior performance for all tasks. The discussion of the challenge results provides practical advice for users and a benchmark for developers

Strategies applied to modify structured and smooth surfaces: A step closer to reduce bacterial adhesion and biofilm formation

Nearly a century has passed since the discovery of the first antibiotics. With each passing decade, more bacterial strains developed resistance towards existing antibiotics. Alternative methods to reduce contamination by bacteria and biofilms have arisen to reduce the pressure on existing or currently developed antibiotics. This review highlights promising approaches to prevent bacterial contamination of the surface. Special attention is paid to antibiotic-free antibacterial strategies that are not affected by bacterial resistance. The approaches have been divided into four categories: (i) anti-adhesive, (ii) contact active, and (iii) biocide attached/biocide release, which can be integrated with (iv) topographical modification. Anti-adhesive approaches can reduce the adhesion between bacteria and a solid surface to prevent bacteria from contacting and contaminating the surface. Contact active approaches provide antibacterial activity by attachment of antibacterial agents to the substratum. Biocide attached/biocide release integrates contact-release of toxic chemicals to bacteria attached to the surface. Lastly, topographical modification relies on approaches to produce small structural features capable of matching cellular components killing bacteria. Combining one or more antibacterial strategies can lead to a more robust approach to deal with dangerous pathogenic bacterial species. In this case, a way forward is by combining various coatings onto topographically modified surfaces, enabling multifunctionality to reduce adhesion and biofilm formation. A perspective on the current antibacterial surface challenge is provided

Selective antifungal activity of silver nanoparticles: A comparative study between Candida tropicalis and Saccharomyces boulardii

In this study, the antifungal activity of AgNPs was tested against C. tropicalis (pathogen fungi) and S. boulardii (probiotic). The effectiveness of the AgNPs was assessed by comparing their antifungal activity with a triazole antifungal drug fluconazole and amphotericin B. The AgNPs have a polygonal-like shape (average size of 35 ± 15 nm) with 1.2% wt. of metallic silver stabilized with 18.8% wt. of polyvinylpyrrolidone (PVP) in 80% wt. of distilled water. The results revealed that 35 μg/mL of fluconazole inhibits 55–60% of both fungal cell growth. As for amphotericin B, 5 μg/mL is sufficient to inhibit more than 95% of both fungal cells. For AgNPs, 25 μg/mL was needed to inhibit 90% of the C. tropicalis cell growth, but remarkably, 50% of the S. boulardii cell population remains viable, which can potentiate cell reproduction. Our results could initiate the development of AgNPs possessing selective specificity against pathogenic fungal species

Application of silver nanoparticles to reduce bacterial growth on leather for footwear manufacturing

Foot infections are difficult to eradicate, patients with diabetes mellitus among others are more susceptible to them, therefore preventive strategies and effective antimicrobial agents are needed. The antimicrobial properties of silver nanoparticles (AgNPs) are well known thus they are a trend for biomedical applications. The aim of this study was to investigate the antibacterial and antifungal activity of leather coated with AgNPs against two bacteria species Pseudomonas mendocina and Pseudomonas syringae, and the fungi Trichophyton mentagrophytes responsible for foot infections. Porcine leather was cut off and sprinkled with solutions containing various concentrations of metallic AgNPs. Inductively coupled plasma-atomic emission spectrometry (ICP-AES) and texture analysis of the leather were performed to quantify the silver metallic concentration metallic silver and to test the effect of AgNPs on leather softness. Antimicrobial activity was measured by agar diffusion test for zone of inhibition (ZoI). The textural analysis of the coated leather showed that the application of AgNPs diminished its softness in a concentration dependency manner. The results from the antimicrobial activity revealed that leather coated with 0.05% of metallic AgNPs had the best antibacterial effect. A decrease in the growth of T. mentagrophytes was observed on the leather coated with 0.25% of metallic AgNPs; however, this concentration was not enough to abolish fungal growing. In conclusion, the application of AgNPs to porcine leather decreased its softness but added beneficial antibacterial properties to avoid bacterial foot infections. Leather coated with AgNPs could be used as a suitable material to prevent foot infections and it could provide added value for shoes manufacturing.</jats:p

Intracellular photophysics of an osmium complex bearing an oligothiophene extended ligand

Intracellular excited-state properties of a photodynamic active Osmium-complex are investigated. The key to the excited-state relaxation is the interplay of 3MLCT and 3ILCT states on the oligothiophene-substituted ligand. We successfully tested the model derived from solution with the complex internalized in cells to bridge the gap between cuvette and in vivo measurements for the first time. This contribution describes the excited-state properties of an Osmium-complex when taken up into human cells. The complex 1 [Os(bpy)2(IP-4T)](PF6)2 with bpy=2,2′-bipyridine and IP-4T=2-{5′-[3′,4′-diethyl-(2,2′-bithien-5-yl)]-3,4-diethyl-2,2′-bithiophene}imidazo[4,5-f][1,10]phenanthroline) can be discussed as a candidate for photodynamic therapy in the biological red/NIR window. The complex is taken up by MCF7 cells and localizes rather homogeneously within in the cytoplasm. To detail the sub-ns photophysics of 1, comparative transient absorption measurements were carried out in different solvents to derive a model of the photoinduced processes. Key to rationalize the excited-state relaxation is a long-lived 3ILCT state associated with the oligothiophene chain. This model was then tested with the complex internalized into MCF7 cells, since the intracellular environment has long been suspected to take big influence on the excited state properties. In our study of 1 in cells, we were able to show that, though the overall model remained the same, the excited-state dynamics are affected strongly by the intracellular environment. Our study represents the first in depth correlation towards ex-vivo and in vivo ultrafast spectroscopy for a possible photodrug