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Recently, new centrifugation protocols for the preparation of platelet-rich fibrin (PRF) have been introduced in an attempt to further improve the beneficial impact of these 2nd generation platelet concentrate membranes. This in-vitro study aimed to compare the biological and physical characteristics of three types of PRF membranes using two different centrifuges with adapted relative centrifugal forces (RCF): leucocyte- and platelet-rich fibrin, advanced platelet-rich fibrin, and advanced platelet-rich fibrin+. Release of growth factors, macroscopic dimensions, cellular content and mechanical properties of the respective membranes, prepared from blood of the same individual were explored. Furthermore, the impact of timing (blood draw-centrifugation and centrifugation-membrane preparation) was assessed morphologically as well as by electron microscopy scanning. No statistically significant differences amongst the three PRF modifications could be observed, neither in their release of growth factors or the cellular content, nor in clot/membrane dimensions. The difference between both centrifuges were negligible when the same g-force was used. A lower g-force, however, reduced membrane tensile strength. Timing in the preparation process had a significant impact. Adaptation of RCF only had a minimal impact on the final characteristics of PRF membranes.

Hydrogels with antioxidant activity have shown to significantly improve the standard of care, because they promote efficient wound healing, i.e. regeneration. N-Acetylcysteine (NAC) is an antioxidant amino acid derivative that promotes complete tissue restoration. However, NAC has anticoagulant properties that may also hinder blood coagulation, which is crucial for hydrogels for wound healing applications. To take advantage of the regenerative activity of NAC while avoiding hampering the hemostasis stage during wound healing, we modified gelatin-NAC with the methacrylate-containing polymers 2-hydroxyethyl methacrylate (H) and poly(ethylene glycol) methyl ether methacrylate (P) to produce Gel-HP-NAC. These hydrogels clotted more blood and faster than Gel and Gel-NAC hydrogels, while maintaining fluid absorption properties adequate to promote wound healing. Similarly, there were more viable human skin fibroblasts after 10 days cultured in Gel-HP-NAC compared with Gel and Gel-NAC. A mouse full-thickness skin wound model demonstrated that Gel-HP-NAC hydrogels improved the wound healing process as compared to the untreated group as proved by the increased wound closure rates and re-epithelialization. Histology of the biopsied tissues indicated more organized collagen deposits on the wounds treated with either Gel-HP-NAC or Gel-NAC than untreated wounds. Our results show that modification of NAC-containing hydrogels through methacrylate-containing polymers improved their wound healing properties, including blood-clotting, and demonstrate the potential of Gel-HP-NAC hydrogels for wound treatment and tissue regeneration.

OBJECTIVE AND BACKGROUND: Little is known about structural and mechanical properties of leukocyte- and platelet-rich fibrin (L-PRF) membranes and even less about the influence of antithrombotic drugs on L-PRF. The aim of this in vitro study is therefore to investigate mechanical properties, fibrin structure and cell content of L-PRF membranes and the impact of anticoagulant therapy on L-PRF. METHODS: Blood samples were obtained from 12 volunteers and supplemented with either no, 1.25 IU, 2.5 IU, 5 IU, or 10 IU enoxaparin. L-PRF membranes were characterized with tensile testing, scanning electron microscopy, and measurement of platelets and leukocytes. Control and enoxaparin-supplemented L-PRF membranes were compared. RESULTS: At 10 IU enoxaparin, no L-PRF membranes could be generated, whereas the low doses of 1.25 and 2.5 IU had no influence on L-PRF properties. The mechanical properties, fibrin networks, and number of platelets and leukocytes of 5 IU supplemented membranes were unlike the control membranes, but were not found to be significantly different because of limited sampling and inter- and intra-variability. CONCLUSION: Low doses of the anticoagulant enoxaparin do not affect mechanical properties, fibrin network, nor cellular content of L-PRF, whereas high doses impair L-PRF generation. ispartof: JOURNAL OF PERIODONTAL RESEARCH vol:55 issue:5 pages:686-693 ispartof: location:United States status: published

Leucocyte- and platelet rich fibrin (L-PRF) is an autologous biomaterial used in regenerative procedures. It has an antimicrobial activity against P. gingivalis although the mechanism is not fully understood. It was hypothesized that L-PRF exudate releases hydrogen peroxide and antimicrobial peptides that inhibit P. gingivalis growth. Agar plate and planktonic culture experiments showed that the antimicrobial effect of L-PRF exudate against P. gingivalis was supressed by peroxidase or pepsin exposure. In developing multi-species biofilms, the antimicrobial effect of L-PRF exudate was blocked only by peroxidase, increasing P. gingivalis growth with 1.3 log genome equivalents. However, no effect was shown on other bacteria. Pre-formed multi-species biofilm trials showed no antimicrobial effect of L-PRF exudate against P. gingivalis or other species. Our findings showed that L-PRF exudate may release peroxide and peptides, which may be responsible for its antimicrobial effect against P. gingivalis. In addition, L-PRF exudate had an antimicrobial effect against P. gingivalis in an in vitro developing multi-species biofilm.

Translation is a fundamental step in gene expression that regulates multiple developmental and stress responses. One key step of translation initiation is the association between eIF4E and eIF4G. This process is regulated in different eukaryotes by proteins that bind to eIF4E; however, evidence of eIF4E-interacting proteins able to regulate translation is missing in plants. Here, we report the discovery of CERES, a plant eIF4E-interacting protein. CERES contains an LRR domain and a canonical eIF4E-binding site. Although the CERES–eIF4E complex does not include eIF4G, CERES forms part of cap-binding complexes, interacts with eIF4A, PABP and eIF3, and co-sediments with translation initiation complexes in vivo. Moreover, CERES promotes translation in vitro and general translation in vivo, while it modulates the translation of specific mRNAs related to light and carbohydrate response. These data suggest that CERES is a non-canonical translation initiation factor that modulates translation in plants. Eukaryotic translation initiation factor 4E-interacting proteins able to regulate translation have not yet been reported in plants. A study now characterizes an eIF4E-interacting protein, CERES, as a non-canonical translation initiation factor that modulates translation in plants.

Various studies have described the biological properties of the Leucocyte- and Platelet Rich Fibrin (L-PRF) such as the antimicrobial effect against wound bacteria, but less is known about the effect against periodontal pathogens. The aim of this study was to evaluate the antibacterial properties of the L-PRF membrane and L-PRF exudate against the main periopathogens cultured on agar plates and in planktonic solution. This study demonstrated the antibacterial effect of the L-PRF membrane against P. intermedia, F. nucleatum, and A. actinomycetemcomitans, but especially against P. gingivalis. The L-PRF exudate also showed a strong inhibition against P. gingivalis on agar plates. No inhibition could be observed for the other bacterial strains. Moreover, L-PRF exudate decreased the number of viable P.gingivalis in a planktonic solution in a dose-dependent way. However, A. actinomycetemcomitans showed an increased growth in planktonic solution when in contact with the L-PRF exudate.

The goal of this work was to evaluate the protective effect of glycerol and PEG-methyl ether methacrylate (PEGMA) coatings, as well as CaCl2 concentration, on the viability of alginate-immobilized Synechococcus elongatus after cold storage. Neither the growth rate nor the generation time of alginate-immobilized S. elongatus was affected by the concentration of CaCl2 after cold preservation by refrigeration at 4 °C for 3.4 years (p > 0.05). However, the type and concentration of the coating, glycerol, or PEGMA, of the alginate beads, affected both growth rate and generation time (p

Plasmonic reversible gas sensors are of paramount importance for the monitoring of indoor environments. Herein, we design and engineer a plasmonic foam, with a high surface area, confined inside a capillary glass tube for the live monitoring of carbon monoxide (CO) in closed environments using surface-enhanced resonance Raman scattering. The illumination of the sensor with light during the flow of air allows the live monitoring of the concentration of atmospheric CO through surface-enhanced resonance Raman scattering. The sensor was prepared with a detection range from 10 to 40 ppm, due to health needs. The results show a sensitive, selective, reversible and robust sensor applicable to the monitoring of CO levels but also to other gas species upon appropriate functionalization.

PURPOSE: The leukocyte- and platelet-rich fibrin block (L-PRF block) is a composite graft that combines a xenograft that is acting as a scaffold with L-PRF membranes that serve as a bioactive nodule with osteoinductive capacity. This study evaluated the properties of the L-PRF block and its components in terms of release of growth factors, cellular content, and structure. MATERIALS AND METHODS: The concentration of transforming growth factor-β1 (TGF-β1), vascular endothelial growth factor (VEGF), platelet-derived growth factor-AB (PDGF-AB) and bone morphogenetic protein-1 (BMP-1) released by a L-PRF membrane (mb) and a L-PRF block were examined with ELISA for five time intervals (0 to 4 hours, 4 hours to 1 day, 1 to 3 days, 3 to 7 days, 7 to 14 days). Those levels in L-PRF exudate and liquid fibrinogen were also evaluated. The cellular content of the liquid fibrinogen, L-PRF membrane and exudate was calculated. The L-PRF block was also analyzed by means of a microCT scan and scanning electron microscopy (SEM). RESULTS: TGF-β1 was the most released growth factor after 14 days, followed by PDGF-AB, VEGF, and BMP-1. All L-PRF blocks constantly released the four growth factors up to 14 days. L-PRF membrane and liquid fibrinogen presented high concentration of leukocytes and platelets. The microCT and SEM images revealed the bone substitute particles surrounded by platelets and leukocytes, embedded in a dens fibrin network. CONCLUSION: The L-PRF block consists of deproteinized bovine bone mineral particles surrounded by platelets and leukocytes, embedded in a fibrin network that releases growth factors up to 14 days. ispartof: INTERNATIONAL JOURNAL OF ORAL & MAXILLOFACIAL IMPLANTS vol:34 issue:4 pages:855-864 ispartof: location:United States status: published

This study sought to improve the mechanical and blood-absorbing properties of collagen sponges, while keeping them compressible, by incorporating blended hydroxyapatite (HA)-starch. Results were compared with CollaPlug(®) (pure collagen). The elastic modulus increased from 1.5±0.2kPa for CollaPlug(®) to 49±8kPa for sponges with composition 1:4:10 (collagen:HA:starch, by weight). The modified microstructure and surface area provided by the starch granules on the sponges improved cell viability. Sponges with composition 1:4:10 maintained their blood-clotting capability with almost no change from 5 to 15min after contact with blood, while CollaPlug(®) diminished to about half its capacity to absorb blood and form clots. Incorporation of HA-starch into the sponges with composition of 1:4:10, increased the elastic modulus of the collagen-HA sponges, making them more structurally robust. The viability of cells and the blood-clotting capability increased with starch incorporation.

Summary Research in polymer network synthesis is mostly focused on materials with absorbent or controlled-release properties. They are important in healthcare applications. Free radical copolymerization is the main route to obtain gels, using monomers and crosslinking agents, but the materials produced by this route are highly heterogeneous. These heterogeneities reduce the efficiency of chemical compounds used in controlled-release applications. Our research is focused on creating new routes of polymer synthesis to reduce these heterogeneities. In this article, we compare gels synthesized by conventional free radical and by reversible addition-fragmentation chain transfer (RAFT) copolymerization of acrylic monomers in supercritical carbon dioxide. These gels are evaluated for controlled drug delivery applications with vitamin B12. The materials were characterized by scanning electron microscopy (SEM), nitrogen adsorption (BET), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). These characterization techniques allowed us to determine the morphology and texture of each hydrogel and to explain how vitamin release performance is affected by these characteristics of the hydrogel.

Hydrogels provide effective alternatives for drug delivery when therapeutics cannot be applied directly to a wound, or if adverse effects are associated with systemic administration. However, drug delivery vehicles need to be biocompatible and biodegradable and exhibit sufficient mechanical strength to withstand handling and different physiological conditions, such as those encountered during topical administration of a therapeutic. Wound healing can be divided into three phases stimulated by transforming growth factor-beta (TGF-&beta, ) and, subsequently, targeted therapeutics have been developed to inhibit this cytokine for the treatment of chronic wounds and to prevent scarring. In this study, the capacity of calcium alginate hydrogels plasticized with poly(ethylene glycol) methyl ether methacrylate (PEGMA) to deliver anti-TGF-&beta, antibodies (1D11.16.8) to a wound was investigated in situ. Three levels of antibodies, 10, 50, and 100 &mu, g, were loaded into calcium-alginate-PEGMA hydrogels and evaluated in an excisional wound model in mice. Hydrogels containing 50 and 100 &mu, g 1D11.16.8 produced less inflammation, accompanied by a marked reduction in collagen deposition and cell infiltration. These findings demonstrate the capacity of calcium-alginate-PEGMA hydrogels to deliver larger proteins, such as antibodies, to the site of a wound.

This study sought to improve the handling, stability to aqueous medium and healing properties of alginate-based three-dimensional structures to be applied as wound scaffolds. Thus, Ca-alginate was plasticized with PEG-methyl ether methacrylate (PEGMA) and blended with the freeze-dried gel of A. vera and aqueous leaves extracts of M. oleifera. Ca-alginate-PEGMA scaffolds remained structurally stable almost four times longer than pure alginate materials, while a high porous architecture required for tissue scaffolding applications was maintained after alginate plasticization with PEGMA. A. vera increased the water uptake capability of the scaffolds and M. oleifera provided antioxidant capacity, anti-inflammatory properties and antimicrobial activity against S. aureus. Blending 1% (w/v) A. vera and 1% (w/v) M. oleifera with Ca-alginate-PEGMA, significantly increased the scaffolds cell proliferation (after 10 days of evaluation), compared with scaffolds without plant extracts. The experimental results showed that Ca-alginate-PEGMA/A. vera/M. oleifera biocomposites have great potential for wound healing applications.

Removal of nitrogen and phosphorous by immobilized microalgae is an advantageous approach for wastewater treatment. Although immobilized microalgae cells remain viable to remove nutrients for several weeks, early leakage of cells because of deterioration of the capsules prevents further use of the immobilized microalgae. This study aimed at increasing the entrapment efficiency of Synechococcus elongatus by core-shell capsules of alginate (as the core) and 2-hydroxyethyl methacrylate (HEMA)-poly(ethylene glycol) methyl ether methacrylate (PEGMA) (as the shell). Cyanobacteria cells were immobilized into: 2 % alginate-1 % CaCl2, 2 % alginate-2 % CaCl2 and 4 % alginate-2 % CaCl2, and submerged into HEMA-PEGMA solution for: 1, 5, or 10 min. A liquid and transparent (93 % transparency) HEMA-PEGMA solution was obtained and used to form a shell over the alginate matrix. Capsules with a shell formed after 10 min of contact with HEMA-PEGMA increased four times (22 days) the cell entrapment efficiency relative to uncoated capsules, independently of alginate or CaCl2, while keeping cells metabolically active and able to remove nutrients.

Synechococcus elongatus cells were immobilized in alginate beads, and the effects of increasing the cross-linker concentration from 2 to 4 % CaCl2 were evaluated, as well as the effects of coating the beads with either glycerol or poly(ethylene glycol) methyl ether methacrylate (PEGMA)—not previously reported for immobilized microalgae—to improve the holding time of the immobilized cells. S. elongatus cells remain metabolically active after coating with glycerol or PEGMA. There is an inverse relation between the glycerol concentration and the chlorophyll a content for the alginate beads cross-linked with 2 % CaCl2. PEGMA diminishes the rate of liberation of cells as its concentration increases, although results suggest the ability of S. elongatus to degrade PEGMA, which increases the growth rate of the liberated cells, because of PEGMA being used as carbon source.

Coating with polymers and re-calcifying have been done to retard the liberation of immobilized cells. Considering that sodium tripolyphosphate (TPP) is highly effective for chelating calcium ions, it is possible to postulate that if a layer of TPP is deposited over calcium alginate beads, the strong interaction between TPP ions and calcium may help in improving their cell holding capacity. In this study, we evaluate and compare the efficiency of cell entrapment between beads of alginate-immobilized microalgae Chlorella vulgaris, Acutodesmus (Scenedesmus) obliquus, and Synechococcus elongatus that were re-calcified, with those that were coated with varying ratios of alginate:TPP. Results indicate that re-calcifying and coating do not limit the growth of the species studied. For C. vulgaris and A. obliquus, coating is more efficient for cell entrapment than re-calcifying. In contrast, for S. elongatus, re-calcifying is more effective than coating, suggesting a relationship between the cell size and the efficiency of cell entrapment.

The goal of this study was to contribute to the interpretation of the kinetics involved in the in vitro demineralization process of bone, which has clinical uses as bone grafts (demineralized bone matrix), as well as for materials science applications. Cortical and cancellous bovine femur bones and cortical antler were demineralized in dilute hydrochloric acid and the kinetic parameters of the demineralization reaction at different temperatures and HCl concentrations were calculated. The rate of demineralization increased with both HCl concentration and temperature. During the demineralization reaction experiments, three different stages were clearly identified: a) in the first stage, the rate constant increased as HCl advanced from the periphery to the core of the sample. b) In the second stage, the demineralization occurred at a steady state, and finally, c) in the third stage, the rate constant diminished. The activation energy for demineralization was calculated for both types of bones.

Fabrication of collagen sponges from type I collagen isolated from cortical bovine femur bone is reported. Collagen was extracted with 0.1 M EDTA by refreshing the solution every 24 h for 9 days. Sodium dodecyl sulfate poly-acrylamide gel electrophoresis (SDS-PAGE) demonstrated the isolation of intact pure type I collagen. The sponges were fabricated by freeze-drying and heat-dehydration cross-linking of collagen solution. The resulting sponges showed fibrils arranged in a highly porous network. These sponges can be used for tissue engineering as well as for bone-like composite fabrication.

A procedure to recover proteases and lipases from the by-products of Monterey sardine (Sardinops sagax caerulea) has been developed, comprising 2 steps: a centrifugation at low temperature to eliminate more than 90% of the initial fat content, and an acetone precipitation step. After this treatment, enzymatic activity increased by 33.8% for lipase, 15.5% for trypsin, 14.8% for chymotrypsin, 93.4% for aminopeptidase, and 19.7% for pepsin. The extents of hydrolysis of fish by-product proteins by endogenous enzyme by-product extract, viscera concentrate extract, and commercial Alcalase® were 62%, 85%, and 28%, respectively. The two extract preparations from sardine by-product (viscera and by-product concentrate extracts) produced 3-fold greater hydrolysis than with the commercial enzyme. The recovery of enzyme concentrates from sardine waste has both ecological and economical advantages for the fish industry.