Surface Of Matrices Research Articles

Solid surface-mediated photochemical transformation of decabromodiphenyl ether (BDE-209) in aqueous solution

Polybrominated diphenyl ethers (PBDEs) are brominated flame retardants which have received considerable attention due to their global distribution, bioaccumulation potential, environmental persistence, and possible toxic effects. In this work, the photodegradation of decabromodiphenyl ether (BDE-209) in aqueous system was investigated by preloading it on the surface of various solid matrices. After 6 h of Xe lamp irradiation, almost complete degradation of BDE-209 was observed on silica gel (SG), with much slower degradation occurring in other adsorbents. The degradation of BDE-209 on SG sample followed pseudo-first-order kinetics, and the observed reaction rate constant was decreased by lowering pH, adding humic acid and increasing the initial BDE-209 concentration. In addition to direct photolysis, BDE-209 could be oxidized by hydroxyl radicals generated from SG, as confirmed by the electron paramagnetic resonance (EPR) technology. Product analysis showed that BDE-209 was mainly decomposed into lower brominated PBDEs, polybrominated dibenzofurans (PBDFs), hydroxylated PBDEs (OH-PBDEs), hydroxylated PBDFs (OH-PBDFs), bromophenols and bromide ions. Thus, consecutive debromination, intramolecular elimination of HBr, hydroxyl addition and the cleavage of ether bond were proposed as the degradation pathways. This study may help understanding the photochemical transformation of solid surface adsorbed BDE-209 in natural surface waters, which is important to evaluate the environmental fate of PBDEs.

Investigation of non-thermal plasma effects on lung cancer cells within 3D collagen matrices

Recent breakthroughs in plasma medicine have identified a potential application for the non-thermal plasma in cancer therapy. Most studies on the effects of non-thermal plasma on cancer cells have used traditional two-dimensional (2D) monolayer cell culture. However, very few studies are conducted employing non-thermal plasma in animal models. Two dimensional models do not fully mimic the three-dimensional (3D) tumor microenvironment and animal models are expensive and time-consuming. Therefore, we used 3D collagen matrices that closely resemble the native geometry of cancer tissues and provide more physiologically relevant results than 2D models, while providing a more cost effective and efficient precursor to animal studies. We previously demonstrated a role for non-thermal plasma application in promoting apoptotic cell death and reducing the viability of A549 lung adenocarcinoma epithelial cells cultured upon 2D matrices. In this study, we wished to determine the efficacy of non-thermal plasma application in driving apoptotic cell death of A549 lung cancer cells encapsulated within a 3D collagen matrix. The percentage of apoptosis increased as treatment time increased and was time dependent. In addition, the anti-viability effect of plasma was demonstrated. Twenty-four hours post-plasma treatment, 38% and 99% of cell death occurred with shortest (15 s) and longest treatment time (120 s) respectively at the plasma-treated region. We found that plasma has a greater effect on the viability of A549 lung cancer cells on the superficial surface of 3D matrices and has diminishing effects as it penetrates the 3D matrix. We also identified the nitrogen and oxygen species generated by plasma and characterized their penetration in vertical and lateral directions within the 3D matrix from the center of the plasma-treated region. Therefore, the utility of non-thermal dielectric barrier discharge plasma in driving apoptosis and reducing the viability of lung cancer cells in 3D collagen matrix indicates a therapeutic potential that warrants further research.

The study of the surface layer of 3D-matrices for tissue engineering

Matrices fabricated by electrospinning from polycaprolactone solutions with human albumin or gelatin to 1,1,1,3,3,3-hexafluoroisopropanol have been investigated. Microstructure of matriх surface was analyzed using scanning electron microscopy. Protein distribution in the surface layer was studied by modification with N-(2-hydroxyethyl)phenazine and X-ray photoelectron spectroscopy. The protein concentration in the surface layer of matrices was up to 12 times higher than in the initial solution, and the lower the protein concentration in the solution, the higher the relative protein content is on the surface of matrices. During incubation of matrices in aqueous solutions protein concentration in the surface layer decreased by less than 10% during the first 30–60 min and remained at this level for a long time (seven days). Treatment with proteinase K resulted in about one-third decrease in protein concentration in the surface layer. Thus, both methods used in this study are applicable for analysis of the surface layer of materials fabricated by electrospinning from mixtures of synthetic and natural polymers; however, X-ray photoelectron spectroscopy appears to be a more informative and convenient method.

Compatibility of cells of the nervous system with structured biodegradable chitosan-based hydrogel matrices

Hydrogel matrices for cell cultivation have been generated by two-photon laser polymerization of unsaturated chitosan derivatives and methacrylated hyaluronic acid. The adhesive and toxic properties of the matrices have been assessed, and the matrices have been shown to have a good compatibility with primary hippocampal cell cultures. The formation of morphologically normal neural networks by cells of the nervous system cultured on the surface of hydrogel matrices has been observed. The metabolic status of dissociated hippocampal cells cultured on the matrices was similar to that of the control cultures, as shown by the results of MTT reductase activity assay. Thus, matrices based on unsaturated polysaccharide derivatives crosslinked by laser irradiation showed good compatibility with differentiated cells of the nervous system and considerable potential for use in neurotransplantation.

RETRACTED ARTICLE: Viscoelastic Behavior and Mechanical Properties of Polypropylene/Nano-Calcium Carbonate Nanocomposites Modified by a Coupling Agent

Polymer blends have the potential to be developed into new resins for specific applications with balanced performance properties and economic advantages. In this paper, polypropylene (PP) and linear low-density polyethylene (LLDPE) blends were investigated at specific composition of PP/LLDPE (60/40) blends (PL40) using a Twin Screw Extruder (TSE). The nano-calcium carbonate (CaCO3) content was varied (between 0-40 wt %), and the composites were investigated using slit die rheometers. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) techniques, revealed the existence of favorable interaction between the surface of CaCO3 nanoparticles and PL40 matrices after surface modification of aminopropyltriethoxy silane (AMPTES) coupling agent. Rheological properties reveal that both the apparent viscosity and the pseudo-plasticity of the PL40 nanocomposites increases with increasing nano-CaCO3 contents and decreases slightly by treated nano-CaCO3 with 2% AMPTES. Dynamic mechanical analysis (DMA) demonstrated that the storage modulus (G′) and glass transition temperature (Tg) are enhanced upon treated nano-CaCO3 with a coupling agent. The results from the mechanical properties exhibited that the impact strength was optimum at 20% nano-CaCO3 content, but tensile strength slightly decreased for untreated PL40 nanocomposites. However, treatment with amino coupling agent improved tensile strength. This attribute to the enhancement of dispersion of the nano-CaCO3 particles in PL40 matrix, leading to improved interfacial adhesion. Treatment of nano-CaCO3 significantly improved the Young’s modulus and flexural modulus compared to the untreated PL40 composites. The crystallization behavior of the composites supported the strong interfaces formed on addition of the amino coupling agent. Furthermore, scanning electron microscopic (SEM) showed evidence of improvement in the dispersion of treated CaCO3 in the PL-40 matrix.

3D compartmented model to study the neurite-related toxicity of Aβ aggregates included in collagen gels of adaptable porosity

Insoluble deposits of β-amyloid (Aβ) are associated to neurodegenerative pathologies, in particular Alzheimer’s Disease (AD). The toxicity of synthetic amyloid-like peptides has been largely demonstrated and shown to depend upon their aggregation state. However, standard 2D cell culture conditions are not well suited to study the role of the close vicinity of Aβ aggregates and growing neurites in the degenerative process. Here, we have designed a compartmented set-up where model neural cells are differentiated on the surface of Aβ-containing collagen matrices. The average pore size can be modulated, from below 0.2μm to more than 0.5μm by simple treatment with collagenase, to respectively hamper or permit neurite outgrowth towards the depth of the matrix. Dense Aβ aggregates (Congo red and ThT-positive) were obtained inside the collagen matrix with a homogeneous distribution and dimensions similar to those observed in post-mortem brain slices from Alzheimer’s patients. The aggregates are not toxic to cells when the pore size is small, in spite of relatively high concentrations of 0.05–0.62mg of peptide per gram of collagen (equivalent to 11.3–113μM). In contrast, on Aβ-containing matrices with large pores, massive neural death is observed when the cells are seeded in the same conditions. It is the first time to our knowledge that Aβ aggregates with a typical morphology of dense plaques are obtained within a porous biomimetic matrix, and are shown to be toxic only when accessible to differentiating cells. Statement of SignificanceInsoluble deposits of β-amyloid (Aβ) are associated to neurodegenerative pathologies, in particular Alzheimer’s Disease (AD). In this study, we have formed Aβ aggregates directly inside a biomimetic collagen matrix loaded with growth factors to induce the differentiation of PC12 or SH-SY6Y cells. For the first time, we show that when the contact between cells and Aβ aggregates is allowed by opening up the matrix porosity, the close vicinity with aggregates induces neurite dystrophy. The compartmented 3D culture model developed and used in this study is a valuable tool to study the cytotoxicity of preformed dense Aβ aggregates and proves that contact between the aggregates and neurons is required to induce neurodegenerative processes.

Biofilm microbial community structure in an urban lake utilizing reclaimed water

Analyses of biofilm community structure may potentially be employed for aquatic ecosystem health assessment, however, to date, biofilm diversity within urban lakes using reclaimed water has not been examined. Accordingly, the microbial community diversity and structure of biofilms from the surface of multiple matrices with varying roughness (0.1, 1.0 and 10.0 μm) were characterized using a suite of molecular techniques including scanning electron microscopy, genetic fingerprinting and phospholipid-derived fatty acid analyses. Samples were largely comprised of inorganic particles, algae and numerous bacterial species; 12 phospholipid-derived fatty acid (PLFA) types were identified, significantly less than typically associated with sewage. Both growth matrix surface roughness and biofilm growth phase were shown to concur with significantly different microbial quantity and community structures. Gram-negative bacteria bacillus i15:03OH and 18:0 were the dominant bacterial genera, collectively comprising ≈75 % of identified PLFA species content. Calculated species diversity (H) and species dominance (D) exhibited identical correlational patterns with measured water quality parameters; significant positive correlations were exhibited with respect to Mg2, while significant negative correlations were found for NO3, TP, BOD, COD, SP, PO4, SO4 and pH. Results indicate that analyses of biofilm formation and structure could be effectively used to undertake integrated assessments of the ecological health of lake systems using reclaimed water. Further work is required to elucidate the optimum conditions for sample collection and analytical interpretation.

Magnetic Field simulation and experimental tests of Special Cross-section Shape Matrices for High Gradient Magnetic Separation

The cross-sectional shape has great influence on the magnetic field characteristics of magnetic matrices in high gradient magnetic separation (HGMS). Suitable cross-sectional matrices can improve the recovery of fine weakly magnetic minerals and reduce mineral processing energy consumption. The performance of four types of cross-sectional shape matrices in the axial configuration of HGMS was studied through numerical simulation combined with experimental tests. The magnetic field generated by the matrices was simulated with ANSYS software, and the magnetic field strength, gradient, and magnetic force were analyzed and compared. The simulation results showed that diamond shaped, elliptical, square, and circular steel matrices reach magnetization saturation successively with increasing the magnetic induction, and the required magnetic induction is approximately 0.7, 0.8, 1, and 1.1 T, respectively. The magnetic field gradient increases with increasing the magnetic induction and then keeps constant when the matrices reach magnetization saturation. Within a wide range of the magnetic induction, the elliptical and square matrices present good magnetic field characteristics. The magnetic force near the surface of the square matrices is the largest but decreases rapidly and consequently has a small effect depth. The magnetic force near the surface of the elliptical matrices is relatively lower but decreases slowly and has a larger effect depth. The diamond-shaped matrices are easy to reach magnetization saturation, and the magnetic force decreases most rapidly. Magnetic matrices were manufactured, and magnetic separation experiments were conducted to verify the simulation results. The experimental results show that the elliptical and square matrices can obtain higher recovery in a wide range of magnetic induction, and the recovery of the elliptical matrices is the highest. The experimental results correspond well with the numerical simulation results, and the results indicate that the magnetic force effect depth is a very important factor influencing the performance of the matrices.

Reactivity of oxide matrix surface during atomic layer deposition

On the basis of the macromolecular concept of the structure of solids and quantitative assessment of the reactivity of the surface of solids using the values of inductive constants, the possibility of the predicted synthesis of nanostructures on the surface of pre-ceramic oxide matrices is shown. The substantiation of the selected approach and the experimental results for the reaction succession of several solid oxides are presented.

Cu2O-directed in situ growth of Au nanoparticles inside HKUST-1 nanocages.

Controllable integration of metal nanoparticles (MNPs) and metal-organic frameworks (MOFs) is attracting considerable attention as the obtained composite materials always show synergistic effects in applications of catalysis, delivery, as well as sensing. Herein, a Cu2O-directed in situ growth strategy was developed to integrate Au nanoparticles and HKUST-1. In this strategy, Cu2O@HKUST-1 core-shell heterostructures, HKUST-1 nanocages, Cu2O@Au@HKUST-1 sandwich core-shell heterostructures and Au@HKUST-1 balls-in-cage heterostructures were successfully synthesized. Cu2O@HKUST-1 core-shell heterostructures were synthesized by soaking Cu2O nanocrystals in benzene-1,3,5-tricarboxylic acid solution. The well-defined Cu2O@HKUST-1 core-shell heterostructures were demonstrated to be dominated by the ratio of Cu2+ cations to btc3- ligands in solution during the period of HKUST-1 formation. Cu2O@Au@HKUST-1 sandwich core-shell or Au@HKUST-1 balls-in-cage heterostructures were obtained by impregnating HAuCl4 into Cu2O@HKUST-1 core-shell heterostructures. Due to the porosity of HKUST-1 and reducibility of Cu2O, HAuCl4 could pass through the HKUST-1 shell and be reduced by the Cu2O core in situ forming Au nanoparticles. Finally, CO oxidation reaction at high temperatures was carried out to assess the catalytic functionality of the obtained composite heterostructures. This strategy can circumvent some drawbacks of the existing approaches for integrating MNPs and MOFs, such as nonselective deposition of MNPs at the outer surface of the MOF matrices, extreme treatment conditions and additional surface modifications.

Nanostructured carbon—Ni(OH)2 composites

Deposition of Ni(OH)2 from an aqueous solution of Ni(N3)2 onto highly porous carbon matrices of two types with different porous structure afforded high-purity nanostructured hydroxide—carbon composites with a regular spatial morphology, which are filled with Ni(OH)2 nanocrystallites (up to 30.9 wt.%) and have high values of specific suface area (up to 1875 m2 g–1) and porosity (up to 2.65 cm3 g–1). Largeand small-angle X-ray diffraction and low-temperature nitrogen absorption on composites showed that nanocrystallites with a brucite-type layered structure form as plates with a thickness of 2—4 nm and a size along the developed face (001) of 25—30 nm in mesopores and on the outer surface of matrices. The degree of mesopore filling with crystallites depends on the mesopore size and the composition of composites; the micropores remain mainly unfilled. The increase in the hydroxide content results in pore size redistribution: in general, the distribution curves shift in favor of smaller mesopore sizes; the portion of pores with sizes comparable with the thickness of filler nanoplates (3—6 nm), as well as the portion of mid-sized pores (20—30 nm) decrease significantly in favor of smaller pores (8—12 nm). Partial blocking (clogging) of pores with filler nanocrystallites was also observed.

Electrochemical plating of I125 on silver matrix for microsources

A technique for plating of I125 on silver matrices by electrochemical plating at alkaline pH was developed and approved. The direct covering of I125 showed to be impossible and to take place only after pre-treatment of matrices by reagents with reductive and chelating properties. According to results of set of experiments the hydrazine hydrate was chosen as activating agent. The developed method includes preparatory activation of surface of silver matrices by processing with 0,01 mM hydrazine solution and then plating of I125 from NaI125 solution in 0,05 M alkaline solution with I125 volumetric activity of 50 mCi/ml (plating voltage of 950 mV). Radioactivity of samples made by developed method with time of coating for 30 or 60 min accounted for 1,12±0,12 mCi and 1.43±0.14 mCi, respectively. Thus, the developed method is efficient technique for plating of I125 on silver matrices, has replicable results and may be used for manufacturing of microsources.

Biomimetic Mineralization of Recombinamer-Based Hydrogels toward Controlled Morphologies and High Mineral Density.

The use of insoluble organic matrices as a structural template for the bottom-up fabrication of organic-inorganic nanocomposites is a powerful way to build a variety of advanced materials with defined and controlled morphologies and superior mechanical properties. Calcium phosphate mineralization in polymeric hydrogels is receiving significant attention in terms of obtaining biomimetic hierarchical structures with unique mechanical properties and understanding the mechanisms of the biomineralization process. However, integration of organic matrices with hydroxyapatite nanocrystals, different in morphology and composition, has not been well-achieved yet at nanoscale. In this study, we synthesized thermoresponsive hydrogels, composed of elastin-like recombinamers (ELRs), to template mineralization of hydroxyapatite nanocrystals using a biomimetic polymer-induced liquid-precursor (PILP) mineralization process. Different from conventional mineralization where minerals were deposited on the surface of organic matrices, they were infiltrated into the frameworks of ELR matrices, preserving their microporous structure. After 14 days of mineralization, an average of 78 μm mineralization depth was achieved. Mineral density up to 1.9 g/cm(3) was found after 28 days of mineralization, which is comparable to natural bone and dentin. In the dry state, the elastic modulus and hardness of the mineralized hydrogels were 20.3 ± 1.7 and 0.93 ± 0.07 GPa, respectively. After hydration, they were reduced to 4.50 ± 0.55 and 0.10 ± 0.03 GPa, respectively. These values were lower but still on the same order of magnitude as those of natural hard tissues. The results indicated that inorganic-organic hybrid biomaterials with controlled morphologies can be achieved using organic templates of ELRs. Notably, the chemical and physical properties of ELRs can be tuned, which might help elucidate the mechanisms by which living organisms regulate the mineralization process.

OP‐4 ADVANCES IN TISSUE ENGINEERING TO REGENERATE THE INTESTINAL EPITHELIUM

Introduction:Irreversible intestinal failure (IF) due to anatomical or functional loss is a devastating condition is associated with significant morbidity and mortality. Patients referred for intestinal transplantation suffer low survival rates due to the high graft‐rejection rate and sepsis as a consequence long‐term immunosuppression. These clinical challenges reveal an urgent need for research into new treatments for IF. Here, we present recent advances in our work on intestinal tissue engineering.Methods:Ethical approval is in place to collect intestinal tissue from patients at Great Ormond Street Hospital. Intestinal crypts were isolated and organoids were cultured as previously described. Decellularization of whole intestinal sections was performed using 2 cycles of the Detergent Enzymatic Treatment (DET) as previously reported. Organoids were cultured on the epithelial surface of the acellular matrix in vitro for 10 days. Cell survival was analysed by histology, immunofluorescence, immunohistochemistry and electron microscopy techniques.Results:Intestinal crypts from the small intestine and colon were successfully isolated from endoscopic biopsies and cultured in order to generate 3 dimensional organoids. The presence of goblet cells and enterocyte cells were confirmed on immunohistochemistry. Whole sections of intestine of varying lengths were successfully decellularized and assessed using H&E staining and scanning electron microscopy. Organoids were seeded onto the epithelial surface of the acellular intestinal matrices and allowed to engraft for a period of 10 days in vitro. The formation of a neo‐epithelium with evidence of a microvillus brush border was evident after 10 days in culture. Furthermore, the cells had successfully migrated into the crypt domains of the matrix.Conclusions:We demonstrate the potential of tissue engineering for intestinal failure by combining organoid cultures with decellularization expertise. Our results confirm human intestinal organoids to be the ideal source of progenitor cells to regenerate the intestinal epithelium, with potential clinical applications for transplantation.

Structural, Morphological and Antibacterial Investigation of Ag-Impregnated Sol-Gel-Derived 45S5 NanoBioglass Systems.

An increasing percentage of ageing population requires 30-year survivability of orthopedic devices that is not possible with the current bioinert materials, having a maximum of 15-year survivability. To satisfy this growing need, a shift is needed from replacement of tissues to regeneration of tissues. This is highly possible through the use of silica-bioactive glasses. However, a failure of implant can occur due to infections even by using such materials. Advances in using silver for antibacterial applications have been commercialized. However, higher concentrations of silver also lead to toxic effects. In this study, nanoBioglass 45S5 (NBG) and Ag-NBG were synthesized by using sol-gel method followed by solution-phase method, respectively. The bioactive crystals such as Na2Ca2Si3O9, CaCO3, and AgPO3, very much needed in the field of bone tissue engineering and in antibacterial strategies, were obtained in the NBG Matrix. The morphological investigation of NBG with 1 mM Ag+ concentrations shows the nanospikes arrangement of size 30-40 nm with spherical porous structure of size 10-20 nm, which supports the formation of collagen molecular fibrils on the surface of NBG matrices and enhances osseointegration. Both gram-positive and gram-negative strains show higher antibacterial activity for nanoBioglass with 1 mM Ag+ concentration.

OSL diagnostics of luminescent materials in a scanning electron microscope

The principles for the application of methods of optically stimulated luminescence (OSL) in a scanning electron microscope (SEM) were developed in this work. A functional scheme for a diagnostic OSL attachment for the investigation of the local properties and distribution parameters of optically active structure complexes in wide-gap dosimeter materials was proposed. Analysis of the dependencies of OSL on the variation in the size of regions that are irradiated with electrons was conducted with anion-defective α-Al2O3 singlecrystals as an example. The possibility of OSL diagnostics of the surface of solid luminescent media and functional matrices with a microscale spatial resolution was shown.

New Ion Exchangers Based on Copolymers: 2,3-(2-Hydroxy-3-Methacryloyloxypropoxy)Naphthalene–Styrene

Synthesis and characterization of the new polymeric ion exchangers with thiol and sulfonyl hydroxide groups are presented. These new sorbents were also compared with polymeric microspheres possessing methylenethiol groups on the surface presented previously. The polymeric cation ion exchangers in the form of microspheres were obtained by the suspension-emulsion polymerization tetrafunctional monomer: 2,3-(2-hydroxy-3-methacryloyloxypropoxy)naphthalene (2,3-NAF.DM) with styrene (St). Next, multistage modification introducing sulfur-containing group (thiol or sulfonyl hydroxide or methylenethiol) on the surface of polymeric matrices was made. In order to obtain sulfonyl hydroxide derivatives the matrices were performed as follows: the parent microspheres were treated by H2SO4 (Method I) or with the addition of oleum (Method II). The thiol groups were introduced in a two-stage reaction. In the first stage chlorosulfonation of parent microspheres in the presence of chlorosulfonic acid was carried out. Finally, the reduction of modified microspheres by using SnCl2·2H2O was conducted. The sulfur group content (elemental analysis, scanning electron microscope EDX SEM), thermal properties (thermogravimetric analysis), porous structure as well as the swelling characteristics of the functional beads were examined. The surface texture was also visualized by the AFM method.

Biodegradable nanofibrous drug delivery systems: effects of metronidazole and ciprofloxacin on periodontopathogens and commensal oral bacteria

The purposes of this study were to fabricate biodegradable polydioxanone (PDS II®) electrospun periodontal drug delivery systems (hereafter referred to as matrices) containing either metronidazole (MET) or ciprofloxacin (CIP) and to investigate the effects of antibiotic incorporation on both periodontopathogens and commensal oral bacteria. Fibrous matrices were processed from PDS polymer solution by electrospinning. Antibiotic-containing PDS solutions were prepared to obtain four distinct groups: 5wt.% MET, 25wt.% MET, 5wt.% CIP, and 25wt.% CIP. Pure PDS was used as a control. High-performance liquid chromatography (HPLC) was done to evaluate MET and CIP release. Dual-species biofilms formed by Lactobacillus casei (Lc) and Streptococcus salivarius (Ss) were grown on the surface of all electrospun matrices. After 4days of biofilm growth, the viability of bacteria on biofilms was assessed. Additionally, antimicrobial properties were evaluated against periodontopathogens Fusobacterium nucleatum (Fn) and Aggregatibacter actinomycetemcomitans (Aa) using agar diffusion assay. A three-dimensional interconnected porous network was observed in the different fabricated matrices. Pure PDS showed the highest fiber diameter mean (1,158 ± 402nm) followed in a descending order by groups 5wt.% MET (1,108 ± 383nm), 25wt.% MET (944 ± 392nm), 5wt.% CIP (871 ± 309nm), and 25wt.% CIP (765 ± 288nm). HPLC demonstrated that groups containing higher amounts (25wt.%) of incorporated drugs released more over time, while those with lower levels (5wt.%) the least. No inhibitory effect of the tested antibiotics was detected on biofilm formation by the tested commensal oral bacteria. Meanwhile, CIP-containing matrices inhibited growth of Fn and Aa. CIP-containing matrices led to a significant inhibition of periodontopathogens without negatively impairing the growth of periodontal beneficial bacteria. Based on the proven in vitro inhibition of periodontitis-related bacteria, future in vivo research using relevant animal models is needed to confirm the effectiveness of these drug delivery systems.

Polysaccharide Fibers as Matrices for Solid-Surface Fluorescence

Fibers of cellulose diacetate (CDA) and chitosan (CTS) of polycationic and polybasic forms were tested as matrices for solid-surface fluorescence (SSF) of several fluorescent probes—eosin Y, trypaflavine, and pyrene. The morphology and surface potential of these matrices were examined. The influence of structural and energetic characteristics of the fibrous polysaccharide materials at SSF of the probes was shown. Fluorescence was studied in aqueous solutions of eosin Y and trypaflavine, in water-ethanolic and water-micellar surfactant media of pyrene, before and after dynamic sorption of the dyes on fibers and in the adsorbed state. The surface of CDA fiber was shown to be capable of sorbing trypaflavine from water and pyrene from water-micellar surfactant media of various types, so it can be a promising matrix for SSF of pyrene and trypaflavine and their chemical analogs. The Coulomb interactions were proposed to determine eosin Y and trypaflavine concentration on the surface of CTS matrices and the SSF of these probes. The CTS fibers were permeable to hydrophobic pyrene dissolved in an ethanol-water medium or solubilized in the micelles of ionic surfactants.

Bacterial inactivation on solid food matrices through supercritical CO2: A correlative study

In this paper the effectiveness of dense phase carbon dioxide (DPCD) treatment to inactivate different bacterial strains inoculated on the surface of solid food matrices is studied. The bacterial survival is investigated on three distinct matrices: Salmonella enterica spiked on fresh cut coconut (Cocos nucifera), Escherichia coli on fresh cut carrot (Daucus carota) and Listeria monocytogenes on dry cured ham surface. Bacterial inactivation experiments are carried out in order to develop and identify mathematical models whose relative performance is assessed in terms of goodness-of-fit and a posteriori statistics obtained after parameters estimation. Operational maps illustrating the time required to achieve an assigned inactivation degree are built in order to guide the choice of the best operating conditions to be used in the process.The results demonstrate the potential of relatively simple correlative models to represent the DPCD pasteurisation process at different experimental conditions, paving the way to more complex model formulation that can be used in DPCD process design and optimisation.