Porous Polylactide Microparticles as Effective Fillers for Hydrogels.

High-strength composite hydrogels based on collagen or chitosan-genipin were obtained via mixing using highly porous polylactide (PLA) microparticles with diameters of 50-75 µm and porosity values of over 98%. The elastic modulus of hydrogels depended on the filler concentration. The modulus increased from 80 kPa to 400-600 kPa at a concentration of porous particles of 12-15 wt.% and up to 1.8 MPa at a filling of 20-25 wt.% for collagen hydrogels. The elastic modulus of the chitosan-genipin hydrogel increases from 75 kPa to 900 kPa at a fraction of particles of 20 wt.%. These elastic modulus values cover a range of strength properties from connective tissue to cartilage tissue. It is important to note that the increase in strength in this case is accompanied by a decrease in the density of the material, that is, an increase in porosity. PLA particles were loaded with C-phycocyanin and showed an advanced release profile up to 48 h. Thus, composite hydrogels mimic the structure, biomechanics and release of biomolecules in the tissues of a living organism.

Chitosan Sponges for Efficient Accumulation and Controlled Release of C-Phycocyanin.

The paper proposed a new porous material for wound healing based on chitosan and C-phycocyanin (C-PC). In this work, C-PC was extracted from the cyanobacteria Arthrospira platensis biomass and purified through ammonium sulfate precipitation. The obtained C-PC with a purity index (PI) of 3.36 ± 0.24 was loaded into a chitosan sponge from aqueous solutions of various concentrations (250, 500, and 1000 mg/L). According to the FTIR study, chitosan did not form new bonds with C-PC, but acted as a carrier. The encapsulation efficiency value exceeded 90%, and the maximum loading capacity was 172.67 ± 0.47 mg/g. The release of C-PC from the polymer matrix into the saline medium was estimated, and it was found 50% of C-PC was released in the first hour and the maximum concentration was reached in 5-7 h after the sponge immersion. The PI of the released C-PC was 3.79 and 4.43 depending on the concentration of the initial solution.

Biomechanical behaviour of PEDOT:PSS-based hydrogels as an electrode for stent integrated enzyme biofuel cells.

The possibility of creating a biofuel cell based on a metal stent was shown in this study. Given the existing stent implantation approaches, the integration of a biofuel cell into a stent naturally entails capacity for biofuel cells to be installed into a human body. As a counter electrode, a hydrogel based on iota-carrageenan, polyvinyl alcohol, and PEDOT:PSS, with an immobilized glucose oxidase enzyme, was proposed. Tension tests demonstrated that the hydrogel mechanical behavior resembles that of a bovine's vein. To obtain an analytical description, the deformation curves were fitted using Gent and Ogden models, prompting the fitting parameters which can be useful in further investigations. During cyclic biaxial studies the samples strength was shown to decreases insignificantly in the first 50 cycles and, further, remains stable up to more than 100 cycles. The biofuel cell was designed with the PEDOT:PSS based material as an anode and a Co-Cr self-expanding stent as a cathode. The maximum biofuel cell power density with a glucose concentration of 5 mM was 7.87 × 10-5 W in phosphate buffer and 3.98 × 10-5 W in blood mimicking buffer. Thus, the biofuel cell integration in the self-expanding stent was demonstrated.

A review of motor neural system robotic modeling approaches and instruments.

In this review, we are considering an actively developing tool in neuroscience-robotic modeling. The new perspective and existing application fields, tools, and methods are discussed. We try to determine starting positions and approaches that are useful at the beginning of new research in this field. Among multiple directions of the research is robotic modeling on the level of muscles fibers and their afferents, skin surface sensors, muscles, and joints proprioceptors. Some examples of technical implementation for physical modeling are reviewed. They are software and hardware tools like event-related modeling algorithms, reduced neuron models, robotic drives constructions. We observe existing drives technologies and prospective electric motor types: switched reluctance and transverse flux motors. Next, we look at the existing examples and approaches for robotic modeling of the cerebellum and spinal cord neural networks. These examples show practical methods for the model neural network architecture and adaptation. Those methods allow the use of cortical and spinal cord reflexes for the network training and apply additional artificial blocks for data processing in other brain structures that transmit and receive data from biologically realistic models.

Electroconductive PEDOT:PSS-based hydrogel prepared by freezing-thawing method.

Biopolymer-based composition with adding of conductive polymer poly-(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT PSS) was made by mixing of iota-carrageenan (CRG), polyvinyl alcohol (PVA) and PEDOT PSS followed by freezing/thawing cycles. The method is environmentally friendly and based on the formation of polymer matrix upon of mixing CRG, PVA and PEDOT PSS and formation of porous physical gel due to freezing/thawing cycles. It is necessary to mention that all components are well-known as biocompatible materials. The resulting material is stable in water and also has swelling capability both in distilled water and physiological solutions. Structure of material was characterized by means of X-ray diffraction, optical and electron microscopy. Electrophysical investigations also were performed. The conductivity of the gel immersed in distilled water is comparable with the dry gel value and close to 0.01 [S/cm].

Draft Genome Sequence of "Halomonas chromatireducens" Strain AGD 8-3, a Haloalkaliphilic Chromate- and Selenite-Reducing Gammaproteobacterium.

Here, we report the complete genome sequence (3.97 Mb) of "Halomonas chromatireducens" AGD 8-3, a denitrifying bacterium capable of chromate and selenite reduction under extreme haloalkaline conditions. This strain was isolated from soda solonchak soils of the Kulunda steppe, Russian Federation.

Methods coagulation/flocculation and flocculation with ballast agent for effective harvesting of microalgae.

The effects of coagulant (FeCl3·6H2O), various flocculants based on polyacrylamide (PAA), polyethylenoxide (PEO) and flocculated biomass as ballast agent, dosage and sedimental time on flocculation efficiency of harvesting Chlorella vulgaris GKV1 cultivated in a laboratory were investigated. The results of this work indicated that the flocculation efficiency achieved about 90% after 5 min of sedimentation when adding of coagulant and flocculant mixture (FeCl3 50 mg/l+PEO based Sibfloc-718 7.5 mg/l) or flocculant with ballast agent (Sibfloc-718 7.5 mg/l+10% flocculated biomass). PAA and PEO showed good flocculation efficiency at dosage of 0.025 and 0.015 g/l, respectively without pH adjustment. Finally, the most suitable flocculation method was discussed in this paper.