Surface Of Matrices Research Articles

Millisecond activity modulation of atomically-dispersed Fe–N–C catalysts

Precious-metal-free transition metal–N–C catalysts containing atomic MeNx centers are promising candidates for the oxygen reduction reaction (ORR) in rechargeable zinc-air batteries. In this study, we report the highly efficient synthesis and activity modulation of Me–N–C (Me = Fe, Co, Ni, and Cu) catalysts utilizing the flash Joule heating technique, accomplished within 200 milliseconds. The instantaneous high temperature (∼3535 K) and rapid heating and cooling rates (above 104 K s–1) induce the formation of atomically-dispersed MeNx sites on the surface of carbon nanotube matrices. This ultrafast thermal shock process not only prevents the aggregation of isolated metal atoms but also achieves catalytic activity modulation through heteroatom engineering. Typically, phosphorus atoms play a crucial role in suppressing nitrogen loss and regulating the local coordination environment of FeNx centers, thereby facilitating the 4 e– electrocatalytic reduction of oxygen. As expected, the phosphorus-doped Fe–N–C catalyst exhibits excellent ORR activity with a high half-wave potential of 0.904 V and a low Tafel slope of 23.1 mV dec–1 in a 0.1 M KOH medium. The assembled zinc-air battery demonstrates a prominent power density of 236.3 mW cm–2 and desirable long-term durability over 400 h, surpassing that of the Pt/C+IrO2-based battery.

TISSUE ENGINEERING MATRIX BASED ON POLYURETHANE: IN VITRO RESEARCH

HighlightsThe article focuses on a new polyurethane-based material that has been developed and tested in vitro. This highly porous material with satisfactory physical and mechanical, hemocompatibility and matrix properties, obtained by using an electrospinning method, is suitable for the fabrication of cardiovascular products. AbstractAim. To manufacture a polyurethane-based tissue engineered matrix and study its physical and mechanical characteristics, hemocompatibility and matrix properties in comparison with decellularized xenopericardium and sheep carotid artery.Methods. Matrices based on polyurethane were produced by electrospinning. The surface structure was studied by scanning electron microscopy, the physical and mechanical characteristics were studied using a Zwick/Roell Universal testing machine, hemocompatibility was studied according to ISO 10993-4-2020, and the matrix properties of the material were studied in a cell experiment with Ea.hy 926.Results. The structure of the 12% polyurethane matrix was represented by a fibrous network with interpenetrating pores. The physical and mechanical characteristics of polyurethane matrices corresponded to the parameters of the carotid artery of sheep more than xenopericardium. Polyurethane had optimal hemocompatibility: hemolysis of erythrocytes did not exceed 0.52%, platelet aggregation corresponded to the aggregation of platelet-rich plasma – 80%. Platelet adhesion to the surface of the polyurethane matrix is statistically significantly lower than adhesion to the xenopericardium (p = 0.0041). Cell adhesion, viability and metabolic activity of Ea.hy 926 cultured on the surface of polyurethane matrices were higher relative to xenopericardium: cell density was 236.3 [198.5; 264.6] cells/mm2 (p = 0.458), viability 19.0 [16.0; 25.0] % (p = 0.0145).Conclusion. Physical and mechanical characteristics, hemocompatibility and matrix properties of polyurethane confirmed its suitability for potential use for the needs of cardiovascular surgery.

Effect of synthesis conditions on morphology and spectral properties of SiO2:DAST composites

SiO2:DAST composites based on SiO2 matrices with a porosity of 30–70% saturated with DAST molecules were synthesized both by evaporation from a solution and by lowering the temperature in a crystallizer. X-ray study of the composites showed the absence of DAST crystalline phase. There was only one luminescence band for all the composites with a maximum in the region of 620–640 nm (at their annealing at 100 °C). A hypsochromic shift (590-565 nm) of the luminescence band maxima of the composites was observed with an increase in their annealing temperature to 200 °C. Annealing at 200 °C also led to a change in the structure of the composite – “filling” of the pores of SiO2 matrices. This was probably due to a decrease in the interaction of the adsorbed DAST cations with the surface of SiO2 matrices due to exfoliation of DAST layers from the xerogel surface into the pores.

Oxygen transmission rates of skin substitutes and graft survival

AimOxygen is required for cell migration into the scaffold and for the survival of the overlying graft in the use of a single-layer scaffold. In the absence of diffusion from the avascular wound base, such as in areas above the bone/tendon, oxygen delivery from the lateral edges of the scaffold is important. This study compared the oxygen permeability of skin scaffolds, currently commercially available in Turkey (Nevelia®, MatriDerm®, and Pelnac®), in the lateral plane. Materials and methodsTo measure oxygen permeability, an interconnected closed system was created. Oxygen permeability was evaluated based on the color change that occurred as a result of the reaction of iron with oxygen. After the dermal matrices placed in the closed system were exposed to oxygen, the color change on the surface of the dermal matrices was measured, and electron microscopic images were recorded to compare deformation before and after the procedure. ResultsTwo scaffolds did not show deformation after the procedure while Pelnac® had minimal deformation. The oxygen rates on the nitrogen side of the test apparatus were found to be 29%, 34%, and 27% for Nevelia®, MatriDerm®, and Pelnac®, respectively; and the oxygen transmission lengths (length of color change) of these scaffolds in the lateral plane were 1, 2, and 0.5 cm, respectively. ConclusionAlthough none of the scaffolds showed significant deformation, and all continued to exhibit their scaffold properties after the procedure, MatriDerm® was determined to be the most suitable scaffold for use in avascular areas, with a 2-cm oxygen transmission length in terms of lateral oxygenation.

Analysis of the effectiveness of various protein coatings for optimizing the endothelialization of polymer matrices

Background. Due to the constant increase in the number of surgeries to restore blood flow in the affected vessels, the development of synthetic prostheses is relevant. One of the key success factors is an increase in the adhesive properties of the inner surface, since the rapid endothelialization of vascular prostheses is considered a factor necessary to prevent thrombosis and neointimal hypertrophy.Aim: To determine the effect of surface modification of polymer matrices with fibrin, fibronectin, or type I collagen on the adhesion and viability of endothelial cells.Material and Methods. Polymer matrices prepared by electrospinning from a mixture of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and poly(ε-caprolactone) were studied. Matrix samples were coated with type I collagen or fibronectin or fibrin. Then, human umbilical vein endothelial cells (HUVEC) were colonized on the matrices and cultured for 3 days. Unmodified matrices and culture plate wells were used as controls. Cell viability was assessed by combined staining with Hoechst 33342 and ethidium bromide. The metabolic activity of the cells was studied using the MTT test. Cell adhesion was analyzed by staining for F-actin. Statistical analysis of the results was performed using the GraphPrism 7.0 program.Results. It was found that the number of adherent cells and their metabolic activity of matrices with collagen did not differ from unmodified ones. Coating with fibronectin demonstrated higher rates of cell adhesion to the surface. However, a rather high level of cell death in this group indicates that such a modification cannot fully ensure the normal functioning of cells. Finally, we observed the best results when using a fibrin coating, which was comparable to culture plastic in terms of adhesion and viability of endothelial cells.Conclusion. Modification of the surface of polymer matrices with fibrin can significantly improve their adhesive properties and can be used in the development of polymer prostheses for small-diameter vessels.

Carbon matrix nanostructured composites as a new type of supercapacitor electrode materials

Carbon matrix nanocomposites C / Au and C / MnxOy are obtained by a reduction of HAuCl4 and KMnO4 precursor solutions with single-walled carbon nanotubes or highly porous carbon materials obtained by high-temperature alkaline activation of various metamorphism degree coals. The morphology of the nanocomposite materials is studied by the electron microscopy. It is found that the filler introduction slightly reduces the specific surface of matrices and, due to the blocking of meso- and micropore volumes, filler nanoparticles do not precipitate in the pores of a predominantly microporous matrix and partially decorate them in mixed-type matrices (meso- and micropores). Nanocomposites have been studied as supercapacitor electrode materials. It is established that decorating the matrix surface with both types fillers (Au, which increases the electrical double layer capacitance, and MnxOy, which is electrochemically active in a given potential window due to the occurrence of Red-Ox electrode processes) results in an increase in the supercapacitor electrodes capacitance. The most significant effect is observed for composites based on the SWCNT and highly porous Boghead in the region of high potential scan rates by a factor of 3.4 – 4.5, and in the region of low rates (2.5 – 2.8), depending on the filler. The results obtained allow one to consider the composites C / Au and C / MnxOy as promising materials for the development of SC electrodes.

Fabrication and Characterization of Polycaprolactone with Retinoic Acid and Cerium Oxide for Anticancer Applications

In the present study, poly (ε-caprolactone) (PCL) composite electrospun nanofibers were fabricated by combining PCL, retinoic acid (RA), and cerium oxide (CeO2). The parameters processing of material fibers by electrospinning were optimized to obtain PCL-based electrospun nanofiber to be used in drug delivery. The results showed that combined solvents and polymer concentration were found to play key roles in determining the morphology of nanofiber. A single solvent (Dimethylformamide DMF, 100%) favored the beads' formation, whereas beadless fibers were produced with mixed solvents(DMF, chloroform, and methanol). The formation of beads was clearly inhibited due to an increased concentration from 10 to 15% w/v of the polymer. Nanofibers of PCL, PCL/RA, PCL/CeO2, and PCL/RA/CeO2 were fabricated and characterized using the combined techniques of SEM (scanning electron microscopy), FTIR (Fourier transform infrared), XRD (X-ray diffraction), TGA (thermogravimetric analysis), contact angle measurements and AFM (atomic force microscopy). The SEM micrographs of RA/CeO2 loaded PCL nanofibers exhibited similar morphology, and none of them showed bead formation or the presence of RA or CeO2 on the surface of the nanofiber matrices. The nanofibers loaded with 0.5% RA/CeO2 drug have the highest diameter (130 ± 33 nm), and the pure PCL nanofibers showed the smallest diameter (74 ± 20 nm) among all the drug-loaded samples evaluated. Also, the XRD analysis displayed the very low crystallinity of RA/CeO2 in PCL loaded with RA/CeO2. The result shows that the drug-loaded nanofiber has similar thermal stability to the PCL nanofiber, indicating that the addition of RA and CeO2 decreases the hydrophobicity. The drug-loaded nanofiber has higher surface roughness than the PCL nanofiber, according to AFM data. Based on the results, PCL/RA/CeO2 nanofiber is considered a potential material for drug delivery applications.

Correlation of adsorbed and embedded palladium species in chitosan composite nanofibers with their catalytic activities for Suzuki reactions

Heterogeneous palladium catalysts play an important role in the synthetic organic chemistry. Palladium species have been adsorbed on the surface of solid matrices or embedded inside solid matrices to prepare recyclable heterogeneous catalysts. Due to the different surrounding environment, these two type palladium species had different electronic properties and catalytic performances. In this study, we fabricated three series of chitosan composite nanofibers with adsorbed and embedded palladium species. Their fiber morphologies and chemical structures were characterized by SEM and FT-IR, respectively. Positron annihilation lifetime spectra (PALS) showed that the intensities (I3) of o-Ps annihilations were all linearly decreased with the increase of palladium contents in the chitosan composite nanofibers. Moreover, compared with the palladium adsorbed chitosan composite nanofibers, the palladium embedded chitosan composite nanofibers had stronger o-Ps annihilation ability, which could be ascribed to the stronger electron donating property of embedded palladium species and higher crosslinking of chitosan molecules by embedded palladium species. At last, the I3 values were successfully correlated with the rate constants of chitosan supported palladium composite nanofibers catalyzed Suzuki reactions of iodobenzene with phenylboric acid. Therefore, we have developed a facile method to distinguish the adsorbed and embedded palladium species by PALS, which can be further related with their catalytic performance.

Time-varying spectral matrix estimation via intrinsic wavelet regression for surfaces of Hermitian positive definite matrices

Intrinsic wavelet transforms and denoising methods are introduced for the purpose of time-varying Fourier spectral matrix estimation. A non-degenerate time-varying spectral matrix constitutes a surface of Hermitian positive definite matrices across time and frequency and any spectral matrix estimator ideally adheres to these geometric constraints. Spectral matrix estimation of a locally stationary time series by means of linear or nonlinear wavelet shrinkage naturally respects positive definiteness at each time-frequency point, without any postprocessing. Moreover, the spectral matrix estimator enjoys equivariance in the sense that it does not nontrivially depend on the chosen basis or coordinate system of the multivariate time series. The algorithmic construction is based on a second-generation average-interpolating wavelet transform in the space of Hermitian positive definite matrices equipped with an affine-invariant metric. The wavelet coefficient decay and linear wavelet thresholding convergence rates of intrinsically smooth surfaces of Hermitian positive definite matrices are derived. Furthermore, practical nonlinear thresholding based on the trace of the matrix-valued wavelet coefficients is investigated. Finally, the time-varying spectral matrix of a nonstationary multivariate electroencephalography (EEG) time series recorded during an epileptic brain seizure is estimated.

Delivery of mRNA vaccines and anti-PDL1 siRNA through non-invasive transcutaneous route effectively inhibits tumor growth

This study aimed to deliver mRNA vaccines and immune checkpoint blockers (ICB) with a transcutaneous immunization (TCI) system based on ethosomes (ETH), exploring the feasibility and effectiveness of their use in tumor treatment. Our data showed that the mannosylated-chitosan-modified ETH (ETH MC ) loaded with mRNA can efficiently transfect dendritic cells (DCs) and induce them maturation. The transdermal patches loaded with mRNA vaccines (termed TCIP) or siRNA against PDL1 (termed TDSP) were prepared by electrospraying microspheres containing mRNA- or siRNA-loaded ETH MC onto the surface of silk fibroin matrices (SFM). The patches showed a good transdermal performance and can effectively deliver nucleic acid molecules into the deep layers of skin. In vivo experiments showed that TCIP loaded with mRNA vaccines can effectively trigger cellular and humoral immune responses. Using mouse melanoma as a model, the combined treatment with TCIP and TDSP showed good antitumor effect, significantly inhibiting tumor growth by improving the infiltration of CD4 + and CD8 + T cells as well as the apoptosis rates in tumor tissues. Our work provides a new strategy for tumor treatment by integrating the non-invasive and convenient of TCI and the flexibility of RNA therapy.

Loss of LRRC33-Dependent TGFβ1 Activation Enhances Antitumor Immunity and Checkpoint Blockade Therapy.

TGFβ has multiple roles and gene products (TGFβ1, -β2, and -β3), which make global targeting of TGFβ undesirable. Expression of TGFβ requires association with milieu molecules, which localize TGFβ to the surface of specific cells or extracellular matrices. Here, we found that LRRC33 was specifically associated with TGFβ1, not TGFβ2 and TGFβ3, and was required for surface display and activation of TGFβ1 on tumor-infiltrating myeloid cells. Loss of LRRC33-dependent TGFβ1 activation slowed tumor growth and metastasis by enhancing innate and adaptive antitumor immunity in multiple mouse syngeneic tumor models. LRRC33 loss resulted in a more immunogenic microenvironment, with decreased myeloid-derived suppressor cells, more active CD8+ T and NK cells, and more skewing toward tumor-suppressive M1 macrophages. LRRC33 loss and PD-1 blockade synergized in controlling B16.F10 tumor growth. Our results demonstrate the importance of LRRC33 in tumor biology and highlight the therapeutic potential of dual blockade of the LRRC33/TGFβ1 axis and PD-1/PD-L1 in cancer immunotherapy.

Estimating decay kinetic parameters and persistence of bacteria in water is essential for future modelling

The aim of this work was to obtain decay kinetic parameters for bacteria sedimentation–resuspension in water. For that, synthetic water matrices prepared with four particle sizes at 2.5 and 5 g/l, were spiked with Escherichia coli and Enterococcus faecalis, selected as Gram-negative and -positive models, respectively. Matrices with bacteria without solids were used as controls. Turbidity was measured and culturable bacteria decay was evaluated using membrane filtration over time. Also, the persistence of culturable E. faecalis and its DNA (detected by real-time PCR) was compared. When no colonies were detected, water matrices were mixed to re-suspend sediments and surface samples were collected and analysed. Spearman test was applied to find correlation between bacteria and turbidity. A persistence coefficient (PC) was defined and several kinetic parameters (decay rate constants, R2, T90) were calculated from experimental data. While culturable E. coli disappeared from the surface of all water matrices with turbidity (p < 0.05), E. faecalis only showed strong and positive correlation in matrices with higher turbidity and smaller particles. E. coli decayed slower when interacting with smallest solids (<44 μm) than with the largest ones (>149 μm), being T90 3–4 times higher in the former. Also, it reappeared and persisted in the surface of all matrices after resuspension despite solid concentration (PC: 0.5−0.9). Instead, culturable E. faecalis, persisted less (lower PC values) in matrices with 2.5 g/l than with 5 g/l and no logic relation was observed for any rate constant with particle size. E. faecalis DNA remained in suspension for longer periods until the end of the experience as seen through their lower rate constants (kDNA < 0.05 h−1). Accurate decay kinetic parameters, like the ones obtained here, are crucial for modelling the fate and transport of bacteria in water and to perform a robust and realistic quantitative risk assessment.

Anti-adhesive effect of chondrocyte-derived extracellular matrix surface-modified with poly-L-lysine.

After an injury, soft tissue structures in the body undergo a natural healing process through specific phases of healing. Adhesions occur as abnormal attachments between tissues and organs through the formation of blood vessels and/or fibrinous adhesions during the regenerative repair process. In this study, we developed an adhesion-preventing membrane with an improved physical protection function by modifying the surface of chondrocyte-derived extracellular matrices (CECM) with anti-adhesion function. We attempted to change the negative charge of the CECM surface to neutral using poly-L-lysine (PLL) and investigated whether it blocked fibroblast adhesion to it and showed an improved anti-adhesion effect in animal models of tissue adhesion. The surface of the membrane was modified with PLL coating (PLL 10), which neutralized the surface charge. We confirmed that the surface characteristics except for the potential difference were maintained after the modification and tested cell attachment in vitro. Adhesion inhibition was identified in a peritoneal adhesion animal model at 1week and in a subcutaneous adhesion model for 4weeks. Neutralized CECM (N-CECM) suppressed fibroblast and endothelial cell adhesion in vitro and inhibited abdominal adhesions in vivo. The CECM appeared to actively inhibit the infiltration of endothelial cells into the injured site, thereby suppressing adhesion formation, which differed from conventional adhesion barriers in the mode of action. Furthermore, the N-CECM remained intact without degradation for more than 4weeks in vivo and exerted anti-adhesion effects for a long time. This study demonstrated that PLL10 surface modification rendered a neutral charge to the polymer on the extracellular matrix surface, thereby inhibiting cell and tissue adhesion. Furthermore, this study suggests a means to modify extracellular matrix surfaces to meet the specific requirements of the target tissue in preventing post-surgical adhesions.

Inactivation of Foodborne Viruses by UV Light: A Review.

Viruses on some foods can be inactivated by exposure to ultraviolet (UV) light. This green technology has little impact on product quality and, thus, could be used to increase food safety. While its bactericidal effect has been studied extensively, little is known about the viricidal effect of UV on foods. The mechanism of viral inactivation by UV results mainly from an alteration of the genetic material (DNA or RNA) within the viral capsid and, to a lesser extent, by modifying major and minor viral proteins of the capsid. In this review, we examine the potential of UV treatment as a means of inactivating viruses on food processing surfaces and different foods. The most common foodborne viruses and their laboratory surrogates; further explanation on the inactivation mechanism and its efficacy in water, liquid foods, meat products, fruits, and vegetables; and the prospects for the commercial application of this technology are discussed. Lastly, we describe UV’s limitations and legislation surrounding its use. Based on our review of the literature, viral inactivation in water seems to be particularly effective. While consistent inactivation through turbid liquid food or the entire surface of irregular food matrices is more challenging, some treatments on different food matrices seem promising.

Cutting temperature measurement in turning of thermoplastic composites using a tool-work thermocouple

Turning of carbon fibre reinforced thermoplastic pipes is used for production of fluid ducts for the aerospace and oil industries. Although thermoplastics are chemically stable, the matrix could be affected by the heat introduced by the machining process. This paper presents how to measure cutting temperature using C/PEEK and C/PA12 material as examples. A suitable method based on a thermocouple circuit and electric conductivity of the carbon fibres is presented, including system calibration. Measurement uncertainties were established for this new method of calibration and measurement for both tested materials. The cutting temperature measurements were analysed by ANOVA and significant factors and its dependence on temperature were identified for further machining process optimization and determination of the predictive model equation. This mathematical cutting temperature model was estimated based on the measurements, and empirical coefficients were identified for selected statistically significant parameters for both composite materials. Because the measured temperatures were above the melting point, the machined surface, chips and structural changes of polymeric matrices were measured in order to prove heat affection.

Sustainable production and co-immobilization of cold-active enzymes from Pseudomonas sp. for BTEX biodegradation

Toluene/o-Xylene Monooxygenase (ToMO) is equipped with a broad spectrum of aromatic substrate specificity (such as BTEX; benzene, toluene, ethylbenzene, and isomers of xylenes). TOMO has can hydroxylate more than a single position of aromatic rings in two consecutive monooxygenation reactions. Catechol 1,2-dioxygenase (C1,2D) is an iron-containing enzyme able to cleave the ring of catechol (the converted product from ToMO) for complete detoxification of BTEX. In this study, cold-active ToMO and C1,2D were produced using newly isolated psychrophilic Pseudomonas S2TR-14 in the minimal salt medium supplemented with crustacean waste and different concentrations of used motor oil (0.2–2% (v/v)). Crude ToMO and C1,2D were immobilized into micro/nano biochar-chitosan matrices and used for BTEX biodegradation. The results showed that the highest enzyme production (12 U/mg for ToMO and 22 U/mg for C1,2D) was achieved at the presence of 0.5% v/v used motor oil compared to the control group without motor oil (0.07 and 0.06 U/mg). High immobilization yield was achieved due to covalent bonding of ToMO (92.26% for micro matrix and 77.20% for nano matrix) and C1,2D (87.57% for micro matrix and 74.79% for nano matrix) with matrices. FTIR spectra confirmed the immobilization of enzymes on the surface of microbiochar and nanobiochar-chitosan matrices as proper support. The immobilization increased the storage stability of the enzymes with more than 50% residual activity after 30 days at 4 ± 1 °C, while the free form of enzymes had less than 10% of its activity. Immobilized enzymes degraded more than 80% of BTEX (~200 mg/L in groundwater and ~10,000 mg/kg in soil) at 10 ± 1 °C in groundwater and soil. Therefore, integrated use of microbiochar and nanobiochar with chitosan for co-immobilization of ToMO and C1,2D can be a potential way to remove petroleum hydrocarbons with higher efficiency from contaminated groundwater and soil.

Magnetic probe-based microrheology reveals local softening and stiffening of 3D collagen matrices by fibroblasts

Changes in extracellular matrix stiffness impact a variety of biological processes including cancer progression. However, cells also actively remodel the matrices they interact with, dynamically altering the matrix mechanics they respond to. Further, cells not only react to matrix stiffness, but also have a distinct reaction to matrix viscoelasticity. The impact of cell-driven matrix remodeling on matrix stiffness and viscoelasticity at the microscale remains unclear, as existing methods to measure mechanics are largely at the bulk scale or probe only the surface of matrices, and focus on stiffness. Yet, establishing the impact of the matrix remodeling at the microscale is crucial to obtaining an understanding of mechanotransduction in biological matrices, and biological matrices are not just elastic, but are viscoelastic. Here, we advanced magnetic probe-based microrheology to overcome its previous limitations in measuring viscoelasticity at the cell-size-scale spatial resolution within 3D cell cultures that have tissue-relevant stiffness levels up to a Young’s modulus of 0.5 kPa. Our magnetic microrheometers exert controlled magnetic forces on magnetic microprobes within reconstituted extracellular matrices and detect microprobe displacement responses to measure matrix viscoelasticity and determine the frequency-dependent shear modulus (stiffness), the loss tangent, and spatial heterogeneity. We applied these tools to investigate how microscale viscoelasticity of collagen matrices is altered by fibroblast cells as they contract collagen gels, a process studied extensively at the macroscale. Interestingly, we found that fibroblasts first soften the matrix locally over the first 32 hours of culture, and then progressively stiffen the matrix thereafter. Fibroblast activity also progressively increased the matrix loss tangent. We confirmed that the softening is caused by matrix-metalloproteinase-mediated collagen degradation, whereas stiffening is associated with local alignment and densification of collagen fibers around the fibroblasts. This work paves the way for the use of measurement systems that quantify microscale viscoelasticity within 3D cell cultures for studies of cell–matrix interactions in cancer progression and other areas.

Numerical simulation for magnetic field analysis and magnetic adsorption behavior of ellipse magnetic matrices in HGMS: Prediction magnetic adsorption behavior via numerical simulation

Magnetic matrices are the core components of HGMS systems. In this study, the induced magnetic field distribution characteristics of ellipse magnetic matrices are investigated via numerical simulation. Besides, the effects of magnetic matrices structure parameters and magnetic field distribution characteristics on the cumulative adsorption behavior of magnetic particles are also discussed. First, the numerical simulation results indicated that compared with the simulation results of a single magnetic matrix, the multi-matrix composite system simulation results demonstrate that an interaction of the induced magnetic fields generated by the superposition of magnetic fields is enhanced with the increase in the long axis size or the decrease in the gap between the matrices, heightening the magnetic induction but leading to the magnetic field gradient and magnetic field forces to significantly decrease near the surface of the matrix. And the rapid reduction of the magnetic field forces around the single matrix leads to a reduction in the range of action. However, to a certain extent, the interaction of the induced magnetic fields also will make the scope of the magnetic field force expand with the decrease in the gap between the matrices. The magnetic cumulative adsorption tests prove that it is feasible to infer the adsorption behavior of magnetic particles through the numerical simulation and theoretical calculations. The adsorption morphology of magnetic particles on the surface of magnetic matrices show that the repulsive region of magnetic particles is perpendicular to the direction of magnetic field, and the adsorption region of magnetic particles is parallel to the direction of magnetic field and with the increase of the size of magnetic matrices, the effective adsorption area of magnetic particles on the surface of magnetic matrices decreases gradually. Besides, with the increase of the horizontal gap between adjacent magnetic matrices, the adsorption thickness of magnetic particles on the surface of magnetic matrices decreases. Moreover, with the expansion of the horizontal gap between the adjacent magnetic matrices, the adsorption amount of the magnetic particles gradually decreases due to the decrease of the adsorption area and fill rate. The adsorption amount of magnetic particles will decrease as the long axis size increases when the fill rate of the magnetic matrices is similar.

Porous Polymer Scaffolds based on Cross-Linked Poly-EGDMA and PLA: Manufacture, Antibiotics Encapsulation, and In Vitro Study.

Porous polymer materials derived from poly(ethylene glycol dimethacrylate) (poly-EGDMA) and antibiotic containing polylactide (PLA) are obtained for the first time. Porous poly-EGDMA monoliths with a system of open interconnected pores are synthesized by a visible light-induced radical polymerization of EGDMA in the presence of 70wt% of porogenic agent, e.g., 1-butanol, 1-hexanol, 1-octanol, or cyclohexanol. The porosity of the obtained polymers is 75-78%. A modal pore size depends on the nature of the porogen and varies from 0.5µm (cyclohexanol) to 12µm (1-butanol). The polymer matrix made with 1-butanol features the presence of pores ranging from 1 to 100µm. The pore surface of poly-EGDMA matrices is inlayered with poly-D,L-lactide (Mn 23 × 103 Da, PDI1.31). The PLA-modified poly-EGDMA retains a porous structure that is similar to the initial poly-EGDMA but with improved strength characteristics. The presence of antibiotic containing PLA ensures a high and continuous antibacterial activity of the hybrid polymeric material for 7 days. The nontoxicity of all the porous matrices studied makes them promising for clinical tests as osteoplastic materials.

Biopolymer Matrices Based on Chitosan and Fibroin: A Review Focused on Methods for Studying Surface Properties

For the creation of tissue-engineered structures based on natural biopolymers with the necessary chemical, physical, adhesive, morphological, and regenerative properties, biocompatible materials based on polysaccharides and proteins are used. This work is devoted to a problem of the technology of polymeric materials for biomedical purposes: the creation of biopolymer tissue engineering matrix and the development of a methodology for studying morphology and functional properties of their surface to establish the prospects for using the material for contact with living objects. The conditions for the formation of scaffolds based on composite materials of chitosan and fibroin determine the structure of the material, the thickness and orientation of molecular layers, the surface morphology, and other parameters that affect cell adhesion and growth. The analysis of studies of the morphology and properties of the surface of biopolymer matrices obtained using different methods of molding from solutions of chitosan and fibroin is carried out.