Blending chitosan-g-poly(caprolactone) with poly(caprolactone) by electrospinning to produce functional fiber mats for tissue engineering applications

Use of electrospun fiber mats for tissue engineering applications has become increasingly prominent. One of the most important polymers in research, poly(ε-caprolactone) (PCL), however, lacks biological performance, easy access to modifications and cellular recognition sites. To improve these properties and to enable further modifications, PCL was blended with chitosan grafted with PCL (CS-g-PCL) and subsequently processed via electrospinning. In this way, chitosan was enriched at the fiber's surface presenting cationic amino groups. The fiber mats were analyzed by various techniques such as scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), and X-ray photoelectron spectroscopy (XPS). Furthermore, analyzing thermal properties and crystallinity, showed that an increased content of CS-g-PCL in blend composition leads to a higher overall crystallinity in produced fiber mats. Blending CS-g-PCL into PCL significantly increased initial cellular attachment and proliferation as well as cell vitality, while maintaining adequate mechanical properties, fiber diameter, and interstitial volume. As proof of principle for easy access to further modification, fluorescently labeled alginate (Alg-FA) was attached to the fiber's surface and verified by CLSM. Hence, blending CS-g-PCL with PCL can overcome an inherent weakness of PCL and create bioactive implants for tissue engineering applications. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48650.     

Hypertensive Effect of Downregulation of the Opioid System in Mouse Model of Different Activity of the Endogenous Opioid System

The opioid system is well-known for its role in modulating nociception and addiction development. However, there are premises that the endogenous opioid system may also affect blood pressure. The main goal of the present study was to determine the impact of different endogenous opioid system activity and its pharmacological blockade on blood pressure. Moreover, we examined the vascular function in hyper- and hypoactive states of the opioid system and its pharmacological modification. In our study, we used two mouse lines which are divergently bred for high (HA) and low (LA) swim stress-induced analgesia. The obtained results indicated that individuals with low endogenous opioid system activity have higher basal blood pressure compared to those with a hyperactive opioid system. Additionally, naloxone administration only resulted in the elevation of blood pressure in HA mice. We also showed that the hypoactive opioid system contributes to impaired vascular relaxation independent of endothelium, which corresponded with decreased guanylyl cyclase levels in the aorta. Together, these data suggest that higher basal blood pressure in LA mice is a result of disturbed mechanisms in vascular relaxation in smooth muscle cells. We believe that a novel mechanism which involves endogenous opioid system activity in the regulation of blood pressure will be a promising target for further studies in hypertension development.     

Multivariate Optimization of the FLC-dc-APGD-Based Reaction-Discharge System for Continuous Production of a Plasma-Activated Liquid of Defined Physicochemical and Anti-Phytopathogenic Properties

To the present day, no efficient plant protection method against economically important bacterial phytopathogens from the Pectobacteriaceae family has been implemented into agricultural practice. In this view, we have performed a multivariate optimization of the operating parameters of the reaction-discharge system, employing direct current atmospheric pressure glow discharge, generated in contact with a flowing liquid cathode (FLC-dc-APGD), for the production of a plasma-activated liquid (PAL) of defined physicochemical and anti-phytopathogenic properties. As a result, the effect of the operating parameters on the conductivity of PAL acquired under these conditions was assessed. The revealed optimal operating conditions, under which the PAL of the highest conductivity was obtained, were as follows: flow rate of the solution equaled 2.0 mL min⁻¹, the discharge current was 30 mA, and the inorganic salt concentration (ammonium nitrate, NH₄NO₃) in the solution turned out to be 0.50% (m/w). The developed PAL exhibited bacteriostatic and bactericidal properties toward Dickeya solani IFB0099 and Pectobacterium atrosepticum IFB5103 strains, with minimal inhibitory and minimal bactericidal concentrations equaling 25%. After 24 h exposure to 25% PAL, 100% (1−2 × 10⁶) of D. solani and P. atrosepticum cells lost viability. We attributed the antibacterial properties of PAL to the presence of deeply penetrating, reactive oxygen and nitrogen species (RONS), which were, in this case, OH, O, O₃, H₂O₂, HO₂, NH, N₂, N₂⁺, NO₂⁻, NO₃⁻, and NH₄⁺. Putatively, the generated low-cost, eco-friendly, easy-to-store, and transport PAL, exhibiting the required antibacterial and physicochemical properties, may find numerous applications in the plant protection sector.     

Analytical strategies to identify and quantify organic admixtures in functionalized mineral model systems

This study describes an analytical approach to identify and quantify organic admixtures, which are increasingly being used in multifunctional additive systems, such as calcium aluminate cement-based dry mix formulations. The investigations refer to a wide range of established organic admixtures used in high performance industrial concrete applications, such as flow agents, retarders, or organic plasticizers, which are added in dosages of up to 5% (to the mass of cement). Based on specific considerations, a consistent approach was outlined by combining the output of complementary analytical techniques. These analytical methods included Thermogravimetric Analysis and Differential Scanning Calorimetry coupled with Mass Spectrometry, in combination with Fourier Transform Infrared Spectroscopy and Morphologically Directed Raman Spectroscopy, as well as Total Carbon Analysis. Within the scope of the aforementioned studies, the applied methods were validated for stringent detection limits (LOD < 0.05%) and precision demands (SD 1% to 7% with R² > 0.99).     

Chemical restriction: strand cleavage by ammonia treatment at 8-oxoguanine yields biologically active DNA

Cleavage of DNA single and double strands at an 8-oxoguanine-containing nucleotide occurs in 90 % yield if the modified oligonucleotide is treated with NH(3) and O(2) at 60 degrees C. The mechanism of this oxidative cleavage reaction was studied, and the reaction was applied to the generation of single-stranded overhangs on PCR-amplified DNA that can be ligated. As an example, the lac Z' gene was amplified by PCR with 8-oxoguanine modified primers, restricted by ammonia treatment, ligated into a plasmid vector, transformed in Escherischia coli cells, and screened for blue colonies. This method guarantees efficiencies comparable to the standard cloning procedure with restriction enzymes, and it allows the design of any 3'-overhang independent of the sequence of the cloned DNA.     

Nanoengineering with residual catalyst from CNT templates

We investigate how residual catalyst from carbon nanotube (CNT) templates can be used to engineer novel functional nanomaterials. CNTs, produced via continuous flow chemical vapour deposition, typically contain catalyst residues in the form of encapsulated metal clusters or of iron oxide nanoparticles attached to the outside of the CNTs. These CNTs are used as sacrificial templates for TiO₂ coatings using benzyl alcohol as a linking agent. Upon oxidation of the CNTs, the encapsulated iron particles dissolve into the TiO₂ lattice and form iron-doped TiO₂ nanotubes without the formation of secondary phases, while the iron oxide particles merely attach to the outer surface. The materials show extended light absorption into the visible range, a requirement for visible-light photocatalyst.     

Determining the effective hydrogen diffusion coefficient in 100Cr6

In the present study, the diffusion constant for hydrogen in hardened 100Cr6 was measured in permeation tests. The tests were conducted on samples of different thicknesses. The diffusivity of hydrogen was also measured in prestrained samples to study the influence of plastic strain on the diffusion rate. A finite element-based diffusion model was applied to confirm the experimental results by computing the concentrations of diffusible hydrogen and trapped hydrogen due to deformation-induced defects. The results showed that the concentration of trapped hydrogen remained very low throughout the plastic strain regime under consideration. The average effective diffusion coefficient of hydrogen in 100Cr6 at 30°C was found to be D_eff = 4.9 × 10⁻¹² m²/s.