Porous Microstructured Surfaces with pH‐Triggered Antibacterial Properties

New antibacterial films are designed with the capability to reversibly regulate their killing and repelling functions in response to variations in environmental pH. These systems consist of porous polystyrene surfaces as the main components and a copolymer bearing pH‐sensitive thiazole and triazole groups as the minor components. These pH‐sensitive groups, located on the surfaces, can be partially protonated at acidic pH levels, increasing the positive charge density of the surfaces and their antibacterial activity. Similarly, their bacterial adhesion and killing efficiencies in response to changes in pH are evaluated by analyzing the bacterial viability of Staphylococcus aureus bacteria on the surfaces under acidic and neutral pH values. It is demonstrated that after only 1 h of incubation with the bacterial suspension in acidic conditions, the surfaces killed the bacteria, while at pH = 7.4, some of the adhered bacteria are removed. Furthermore, the surface topography exerts an important role by intensifying this response.     

Implementation of at‐line capillary zone electrophoresis for fast and reliable determination of adenovirus concentrations in vaccine manufacturing

A CZE method was validated and implemented for fast and accurate in‐process determination of adenovirus concentrations of downstream process samples obtained during manufacturing of adenovirus vector‐based vaccines. An analytical‐quality‐by‐design approach was embraced for method development, method implementation, and method maintenance. CZE provided separation of adenovirus particles from sample matrix components, such as cell debris, residual DNA and proteins. The intermediate precision of the virus particle concentration was 6.9% RSD and the relative bias was 2.3%. In comparison, the CZE method is intended to replace a quantitative polymerase chain reaction method which requires three replicates in three analytical runs to achieve an intermediate precision of 8.1% RSD. Given that, in addition, the time from sampling till reporting results of the CZE method was less than 2 h, whereas quantitative polymerase chain reaction requires 3 days, it follows that the CZE method enables faster processing times in downstream processing.     

Solid-phase synthesis of biaryl cyclic peptides containing a histidine-tyrosine linkage

A solid-phase strategy for the synthesis of biaryl cyclic peptides containing a side-chain to side-chain His-Tyr linkage was developed. The key step was the macrocyclization of a linear peptidyl resin incorporating a 5-bromohistidine and a 3-boronotyrosine via the formation of the biaryl bond by means of a microwave-assisted Suzuki-Miyaura reaction. This method allowed direct access to biaryl cyclic peptides containing a 3- or 5-amino acid ring and bearing the histidine residue at the N- or the C-terminus, being especially conducive for analogues in which this amino acid is located at the C-terminus. This study also served to establish a strategy for the synthesis of biaryl cyclic peptides derived from the two hemispheres of the natural biaryl bicyclic peptides aciculitins.     

Low-Temperature Dynamical Transition in Lipid Bilayers Detected by Spin-Label ESE Spectroscopy

Data on neutron scattering in biological systems show low-temperature dynamical transition between 170 and 230 K manifesting itself as a drastic increase of the atomic mean-squared displacement, 〈x²〉, detected for hydrogen atoms in the nano- to picosecond time scale. For spin-labeled systems, electron spin echo (ESE) spectroscopy—a pulsed version of electron paramagnetic resonance—is also capable of detection of dynamical transition. A two-pulse ESE decay in frozen matrixes is induced by spin relaxation arising from stochastic molecular librations, and allows to obtain the 〈α²〉τ_c parameter, where 〈α²〉 is a mean-squared angular amplitude of the motion and τ_c is the correlation time lying in the sub- and nanosecond time ranges. In this work, the ESE technique was applied to spin-labeled amphiphilic molecules of three different kinds embedded in bilayers of fully saturated 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and mono-unsaturated 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipids. Two-pulse ESE data revealed the appearance of stochastic librations above 130 K, with the parameter 〈α²〉τ_c obeying the Arrhenius type of temperature dependence and increasing remarkably above 170–180 K. A comparison with a dry sample suggests that onset of motions is not related with lipid internal motions. Three-pulse ESE experiments (resulting in stimulated echos) in DPPC bilayers showed the appearance of slow molecular rotations above 170–180 K. For D₂O-hydrated bilayers, ESE envelope modulation experiments indicate that isotropic water molecular motions in the nearest hydration shell of the bilayer appear with a rate of ~?10⁵ s^?1 in the narrow temperature range between 175 and 179 K. The similarity of the experimental data found for three different spin-labeled compounds suggests a cooperative character for the ESE-detected molecular motions. The data were interpreted within a model suggesting that dynamical transition is related with overcoming barriers, of 10–20 kJ/mol height, existing in the system for the molecular reorientations.     

Overview of the New OMAH Technique for Scaling OMA Mode Shapes

Methods for scaling mode shapes determined by operational modal analysis (OMA) have been extensively investigated in the last years. A recent addition to the range of methods for scaling OMA mode shapes is the so-called OMAH technique, which is based on exciting the structure by harmonic forces applied by an actuator. By applying harmonic forces in at least one degree-of-freedom (DOF), and measuring the response in at least one response DOF, while using at least as many frequencies as the number of mode shapes to be scaled, the mode shape scaling (modal mass) of all modes of interest may be determined. In previous publications on the method the authors have proven that the technique is easy and robust to apply to both small scale and large scale structures. Also, it has been shown that the technique is capable of scaling highly coupled modes by using an extended multiple reference formulation. The present paper summarizes the theory of the OMAH method and gives recommendations of how to implement the method for best results. It is pointed out, as has been shown in previous papers, that the accuracy of the mode scaling is increased by using more than one response DOF, and by selecting DOFs with high mode shape coefficients. To determine the harmonic force and responses, it is recommended to use the three-parameter sine fit method. It is shown that by using this method, the measurement time can be kept short by using high sampling frequency and bandpass filtering whereas spectrum based methods require long measurement times. This means that even for structures with low natural frequencies, the extra measurement time for scaling the mode shapes can be kept relatively short.     

Beneficial Effect of Quercetin on Erythrocyte Properties in Type 2 Diabetic Rats

Diabetes mellitus is characterized by tissue oxidative damage and impaired microcirculation, as well as worsened erythrocyte properties. Measurements of erythrocyte deformability together with determination of nitric oxide (NO) production and osmotic resistance were used for the characterization of erythrocyte functionality in lean (control) and obese Zucker diabetic fatty (ZDF) rats of two age categories. Obese ZDF rats correspond to prediabetic (younger) and diabetic (older) animals. As antioxidants were suggested to protect erythrocytes, we also investigated the potential effect of quercetin (20 mg/kg/day for 6 weeks). Erythrocyte deformability was determined by the filtration method and NO production using DAF-2DA fluorescence. For erythrocyte osmotic resistance, we used hemolytic assay. Erythrocyte deformability and NO production deteriorated during aging—both were lower in older ZDF rats than in younger ones. Three-way ANOVA indicates improved erythrocyte deformability after quercetin treatment in older obese ZDF rats only, as it was not modified or deteriorated in both (lean and obese) younger and older lean animals. NO production by erythrocytes increased post treatment in all experimental groups. Our study indicates the potential benefit of quercetin treatment on erythrocyte properties in condition of diabetes mellitus. In addition, our results suggest potential age-dependency of quercetin effects in diabetes that deserve additional research.     

Synthesis of Branched Polyglucans by the Tandem Action of Potato Phosphorylase and Deinococcus geothermalis Glycogen Branching Enzyme

An enzymatic tandem reaction is described in which the enzymes phosphorylase and Deinococcus geothermalis glycogen branching enzyme (Dg GBE) catalyze the synthesis of branched polyglucans from glucose‐1‐phosphate (G‐1‐P). Phosphorylase consumes G‐1‐P and polymerizes linear amylose while Dg GBE introduces branching points on the α‐(1 → 6) positions by reshuffling short oligosaccharides. The resulting branched polyglucans have an unusually high degree of branching of 11%.

     

N-Glycosylation Profiling of Human Blood in Type 2 Diabetes by Capillary Electrophoresis: A Preliminary Study

Currently, diagnosing type 2 diabetes (T2D) is a great challenge. Thus, there is a need to find rapid, simple, and reliable analytical methods that can detect the disease at an early stage. The aim of this work was to shed light on the importance of sample collection options, sample preparation conditions, and the applied capillary electrophoresis bioanalytical technique, for a high-resolution determination of the N-glycan profile in human blood samples of patients with type 2 diabetes (T2D). To achieve the profile information of these complex oligosaccharides, linked by asparagine to hIgG in the blood, the glycoproteins of the samples needed to be cleaved, labelled, and purified with sufficient yield and selectivity. The resulting samples were analyzed by capillary electrophoresis, with laser-induced fluorescence detection. After separation parameter optimization, the capillary electrophoresis technique was implemented for efficient N-glycan profiling of whole blood samples from the diabetic patients. Our results revealed that there were subtle differences between the N-glycan profiles of the diabetic and control samples; in particular, two N-glycan structures were identified as potential glycobiomarkers that could reveal significant changes between the untreated/treated type 2 diabetic and control samples. By analyzing the resulting oligosaccharide profiles, clinically relevant information was obtained, revealing the differences between the untreated and HMG-CoA reductase-inhibitor-treated diabetic patients on changes in the N-glycan profile in the blood. In addition, the information from specific IgG N-glycosylation profiles in T2D could shed light on underlying inflammatory pathophysiological processes and lead to drug targets.