Uncoated Control Research Articles

Anti-inflammatory coating of hernia repair meshes: a 5-rabbit study.

PurposePolymeric mesh implantation has become the golden standard in hernia repair, which nowadays is one of the most frequently performed surgeries in the world. However, many biocompatibility issues remain to be a concern for hernioplasty, with chronic pain being the most notable post-operative complication. Oxidative stress appears to be a major factor in the development of those complications. Lack of material inertness in vivo and oxidative environment formed by inflammatory cells result in both mesh deterioration and slowed healing process. In a pilot in vivo study, we prepared and characterized polypropylene hernia meshes with vitamin E (α-tocopherol)-a potent antioxidant. The results of that study supported the use of vitamin E as potential coating to alleviate post-surgical inflammation, but the pilot nature of the study yielded limited statistical data. The purpose of this study was to verify the observed trend of the pilot study statistically.MethodsIn this work, we conducted a 5-animal experiment where we have implanted vitamin E-coated and uncoated control meshes into the abdominal walls of rabbits. Histology of the mesh-adjacent tissues and electron microscopy of the explanted mesh surface were conducted to characterize host tissue response to the implanted meshes.ResultsAs expected, modified meshes exhibited reduced foreign body reaction, as evidenced by histological scores for fatty infiltrates, macrophages, neovascularization, and collagen organization, as well as by the surface deterioration of the meshes.ConclusionIn conclusion, results indicate that vitamin E coating reduces inflammatory response following hernioplasty and protects mesh material from oxidative deterioration.

Delaying ripening of ‘Bartlett’ pears (Pyrus communis) during long-term simulated industrial cold storage: Mechanisms and validation of chitosan coatings with cellulose nanocrystals Pickering emulsions

Chitosan edible coatings with cellulose nanocrystals Pickering emulsions were investigated at different oleic acid concentrations as coatings to extend storage of ‘Bartlett’ pears by delaying ripening. Pear coatings contained 10 or 20 g oleic acid/kg emulsion (1OA, 2OA). A 7-month simulated industrial storage trial (−1.1 °C) was conducted against carnauba wax-based coating, controlled atmosphere storage (CAS), and uncoated control. The 2OA maintained the highest peel chlorophyll (P < 0.05) when ripened after 3 months, significantly higher than control and carnauba wax throughout the 7 months. Respiration rate and ethylene production peak of 2OA and CAS pears while ripening in ambient conditions were delayed 2 months compared with control pears, and ethylene production peak of 2OA pears had the lowest intensity (31.91 μL/Lgh), significantly (P < 0.05) lower than CAS and control pears. When ripened after 7 months, 2OA and 1OA pears maintained equivalent titratable acidity (~0.23 g/100 mL) and total soluble solids (12.8 g/100 g) to each other, significantly (P < 0.05) different from all other treatments. The 2OA emulsion coating therefore preserved ‘Bartlett’ pears better than 1OA and carnauba wax coatings and competitively with CAS, providing a feasible and accessible postharvest preservation alternative.

The effect of strontium and silicon substituted hydroxyapatite electrochemical coatings on bone ingrowth and osseointegration of selective laser sintered porous metal implants.

Additive manufactured, porous bone implants have the potential to improve osseointegration and reduce failure rates of orthopaedic devices. Substantially porous implants are increasingly used in a number of orthopaedic applications. HA plasma spraying–a line of sight process—cannot coat the inner surfaces of substantially porous structures, whereas electrochemical deposition of calcium phosphate can fully coat the inner surfaces of porous implants for improved bioactivity, but the osseous response of different types of hydroxyapatite (HA) coatings with ionic substitutions has not been evaluated for implants in the same in vivo model. In this study, laser sintered Ti6Al4V implants with pore sizes of Ø 700 μm and Ø 1500 μm were electrochemically coated with HA, silicon-substituted HA (SiHA), and strontium-substituted HA (SrHA), and implanted in ovine femoral condylar defects. Implants were retrieved after 6 weeks and histological and histomorphometric evaluation were compared to electrochemically coated implants with uncoated and HA plasma sprayed controls. The HA, SiHA and SrHA coatings had Ca:P, Ca:(P+Si) and (Ca+Sr):P ratios of 1.53, 1.14 and 1.32 respectively. Electrochemically coated implants significantly promoted bone attachment to the implant surfaces of the inner pores and displayed improved osseointegration compared to uncoated scaffolds for both pore sizes (p<0.001), whereas bone ingrowth was restricted to the surface for HA plasma coated or uncoated implants. Electrochemically coated HA implants achieved the highest osseointegration, followed by SrHA coated implants, and both coatings exhibited significantly more bone growth than plasma sprayed groups (p≤0.01 for all 4 cases). SiHA had significantly more osseointegration when compared against the uncoated control, but no significant difference compared with other coatings. There was no significant difference in ingrowth or osseointegration between pore sizes, and the bone-implant-contact was significantly higher in the electrochemical HA than in SiHA or SrHA. These results suggest that osseointegration is insensitive to pore size, whereas surface modification through the presence of an osteoconductive coating plays an important role in improving osseointegration, which may be critically important for extensively porous implants.

Inhibiting Corrosion of Biomedical-Grade Ti-6Al-4V Alloys with Graphene Nanocoating

The identification of metal ions and particles in the vicinity of failed implants has raised the concern that biomedical titanium alloys undergo corrosion in healthy and infected tissues. Various surface modifications and coatings have been investigated to prevent the deterioration and biocorrosion of titanium alloys but so far with limited success. Graphene is a cytocompatible atom-thick film made of carbon atoms. It has a very high surface area and can be deposited onto metal objects with complex shapes. As the carbon lattice has a very small pore size, graphene has promising impermeability capacity. Here, we show that graphene coating can effectively protect Ti-6Al-4V from corrosion. Graphene nanocoatings were produced on Ti-6Al-4V grade 5 and 23 discs and subjected to corrosive challenge (0.5M NaCl supplemented with 2-ppm fluoride, pH of 2.0) up to 30 d. The linear polarization resistance curves and electrochemical impedance spectroscopy analysis showed that the graphene-coated samples presented higher corrosion resistance and electrochemical stability at all time points. Moreover, the corrosion rate of the graphene-coated samples was very low and stable (~0.001 mm/y), whereas that of the uncoated controls increased up to 16 and 5 times for grade 5 and 23 (~0.091 mm/y) at the end point, respectively. The surface oxidation, degradation (e.g., crevice defects), and leaching of Ti, Al, and V ions observed in the uncoated controls were prevented by the graphene nanocoating. The Raman mappings confirmed that the graphene nanocoating presented high structural stability and resistance to mechanical stresses and chemical degradation, keeping >99% of coverage after corrosion challenge. Our findings open the avenues for the use of graphene as anticorrosion coatings for metal biomedical alloys and implantable devices.

Novel Edible Coating of Starch-Based Stenospermocarpic Mango Prolongs the Shelf Life of Mango “Ataulfo” Fruit

Edible coatings based on 2% starch (w/v) extracted from tropical fruits were applied on stenospermocarpic mango fruits with the objective to prolong its shelf life during storage and give them an added value since they have no commercial value. In this regard, stenospermocarpic mangoes were coated with starch from banana “Pear” (T1 and T2), starch from soursop (T3 and T4), and starch from stenospermocarpic mango (T5 and T6), and two uncoated control treatments (T7 and T8). The fruit of T1, T3, T5, and T7 treatments were stored for 15 days (10 days at 10 ± 2°C and then at 22 ± 2°C for 5 days). The fruit of T2, T4, T6, and T8 treatments were stored for 10 days at 22 ± 2°C. Data were analyzed with a 4×2 factorial experimental design. Weight loss (g), firmness (N), total soluble solids content (%), titratable acidity (%), and color (L∗h∗C∗) were evaluated. The fruit coated with mango starch (T5) showed less weight loss (2.57%), greater firmness (18.6 N), as well as a high content of TSS (28.76%) compared with the control. The T5 extended the shelf life of the fruit up to 15 days (10 days at 10 ± 2°C and 5 days at 22 ± 2°C).

Comparison of Diazeniumdiolated Dialkylhexanediamines as Nitric Oxide Release Agents on Nonthrombogenicity in an Extracorporeal Circulation Model.

When blood from a patient is circulated through extracorporeal circuits (ECCs), such as in cardiopulmonary bypass or extracorporeal life support, platelets in the blood are activated and form a thrombus. This is prevented clinically with a range of different systemic anticoagulation agents (e.g., heparin); however, this increases a patient's risk of hemorrhage. Previous work with nitric oxide (NO) releasing materials using the combined diazeniumdiolated diamine, N-N-di-N'-butyl-1,6-hexanediamine (DBHD), and a polymer-linked thrombin inhibitor, argatroban (AG), showed significant nonthrombogenicity in ECCs using a 4 h rabbit model. Herein, we evaluated if diazeniumdiolated N-N-di-N'-propyl-1,6-hexanediamine (DPHDN2O2), which has a slightly lower degree of lipophilicity compared to DBHDN2O2, would provide similar nonthrombogenicity as the AG/DBHDN2O2-polymer-coated circuits. While DPHDN2O2 releases NO at a higher flux rate than DBHDN2O2 when coated (within CarboSil polymer) on the inner wall of polyvinyl chloride tubing, neither coated circuit significantly affected animal hemodynamics. Both diazeniumdiolated diamines, in combination with immobilized AG or alone, significantly reduced thrombus formation similarly in the 4 h rabbit model (vs uncoated control): AG/DBHDN2O2: 0.12 ± 0.03 cm2; DBHDN2O2: 2.57 ± 0.82 cm2; AG/DPHDN2O2: 0.68 ± 0.22 cm2; DPHDN2O2: 1.87 + 1.26 cm2; uncoated control: 6.95 ± 0.82 cm2. AG/DPHDN2O2 was no different than AG/DBHDN2O in preserving platelet count and function. In addition, AG did not leach into the systemic circulation as the total clotting times were insignificantly different from the baseline values (AG/DPHDN2O2: 12.7 + 0.5 s (n = 3); AG/DBHDN2O2: 12.3 + 0.7 s (n = 3); baseline: 13.9 + 0.3 s (n = 13)). Based on these results, both DPHDN2O2 and DPHDN2O2 are good candidates as NO donor molecules for creating nonthrombogenic polymer coatings for ECCs.

Laboratory accelerated and field exposure testing of MgRP and MgORP on AA2024-T351: Chemical and electrochemical protection effects

Two Mg-based coatings consisting of Mg-rich primer (MgRP) and MgO-rich primer (MgORP) with and without topcoat were exposed to laboratory accelerated lifecycle testing (LALT) and outdoor field environments. The coatings were tested in parallel exposure studies utilizing ASTM B117, modified ASTM B117 (cyclic wet-dry, dark-UV exposure in ASTM synthetic ocean water), rural inland (Charlottesville, VA), and coastal marine (Kennedy Space Center) field exposure. Several characterization and electrochemical diagnostic techniques were used to continuously assess coating performance as a function of time in various exposures, enabling comparison of LALT to field exposures. The coating systems were evaluated with respect to the intact coating and to a machined scribe defect. The fate of Mg2+ upon dissolution of Mg and MgO with respect to pigment depletion, corrosion product formation, and repartitioning from the coating into the scribe was monitored with XRD and EDS. The capacity for MgRP and MgORP to provide barrier, cathodic, and chemical corrosion protection to AA2024-T351 substrate was evaluated. The ultimate ability of these coatings to protect the AA2024-T351 substrate both in the scribe and under the coating was gauged with optical profilometry assessment of corrosion damage. The Mg and MgO-based coating systems exhibited several desirable aspects of a corrosion preventative coating. The corrosion damage quantified both under the intact coating and within the scribe was much less than the corrosion damage measured on uncoated controls. Within a given exposure, the reduction of corrosion damage in the scribe correlated with the amount of Mg2+ which was released from the coating and repartitioned into the scribe. The open circuit potential of the coated substrate was depressed to more negative potentials than the bare substrate in 5 wt% NaCl, with non-topcoated samples establishing more negative potentials. The barrier properties remained high throughout the exposures for topcoated samples, which also better preserved the pigment from depletion. Comments are made regarding differences between the Mg and MgO-based coatings and the various laboratory and field exposures.

Accentuated osseointegration in osteogenic nanofibrous coated titanium implants

Anchoring of endosseous implant through osseointegration continues to be an important clinical need. Here, we describe the development of superior endosseous implant demonstrating enhance osseointegration, achieved through surface modification via coating of osteogenic nanofibres. The randomized bio-composite osteogenic nanofibres incorporating polycaprolactone, gelatin, hydroxyapatite, dexamethasone, beta-glycerophosphate and ascorbic acid were electrospun on titanium implants mimicking bone extracellular matrix and subsequently induced osteogenesis by targeting undifferentiated mesenchymal stem cells present in the peri-implant niche to regenerate osseous tissue. In proof-of-concept experiment on rabbit study models (n = 6), micro-computed tomography (Micro-CT), histomorphometric analysis and biomechanical testing in relation to our novel osteogenic nanofibrous coated implants showed improved results when compared to uncoated controls. Further, no pathological changes were detected during gross examination and necropsy on peri-implant osseous tissues regenerated in response to such coated implants. The findings of the present study confirm that osteogenic nanofibrous coating significantly increases the magnitude of osteogenesis in the peri-implant zone and favours the dynamics of osseointegration.

Potential use of newly isolated bacteriophage as a biocontrol against Acidovorax citrulli.

Acidovorax citrulli, the gram-negative bacteria that causes bacterial fruit blotch (BFB), has been responsible for huge worldwide economic losses in watermelon and melon production since 1980. No commercial cultivar resistant to BFB has been reported. Of the two reported genotypes of A. citrulli, genotype I is the main causal agent of BFB in melon and genotype II causes disease in watermelon. After the isolation of the first bacteriophage against A. citrulli (ACP17), efforts have been made to isolate bacteriophages with wider host ranges by collecting samples from watermelon, pumpkin, and cucumber. The newly isolated phage ACPWH, belonging to the Siphoviridae family, has a head size of 60 ± 5nm and tail size of 180 ± 5nm, and can infect 39 out of 42 A. citrulli strains. ACPWH has genome size of 42,499 and GC content of 64.44%. Coating watermelon seeds with bacteriophage ACPWH before soil inoculation with A. citrulli resulted in 96% germination and survival, compared to 13% germination of uncoated control seeds. These results suggest that phage ACPWH may be an effective and low-cost biocontrol agent against BFB.

THE IMPACT OF NANO CHITOSAN AND NANO SILICON COATINGS ON THE QUALITY OF CANINO APRICOT FRUITS DURING COLD STORAGE

This work was carried out during 2016 and 2017 seasons in post-harvest Lab. Pomology Dept. Cairo University, Egypt. The quality and internal (physical and chemical) changes in apricot fruits (Prunus armeniaca L.) coated with different treatments of Nano chitosan and Nano silicon were studied after different storage periods of cold storage at 1°C and 90-95% (RH). Nano chitosan was prepared with 0.5% concentration and Nano silicon was prepared with 2% concentration, each of them was tested individuallyor in combination with Thiabendazole (TBZ). The changes in fruit firmness, weight loss, discarded fruit percentage, fruit panel, total acidity (TA), total soluble solids (TSS), and ascorbic content (Vitamin C) at intervals were estimated during 7 weeks. The results of the two successive seasons indicated that the application of Nano chitosan and silicon coatings maintained fruit firmness compared with the control (dipped in TBZ) without significant differences. The application with 0.5% Nano chitosan + TBZ treatment maintained higher firmness values. On the other hand, Nano-chitosan coating + TBZ treatment maintained fruit acidity, fruit panel test and Vitamin C content more than the uncoated control and other treatments without significant differences. While, all coating treatments increased TSS values and discarded fruit percentage compared with the control without significant differences. The lowest value for each of TSS and fresh weight loss percentage was achieved by Nano chitosan 0.5% + TBZ treatment. Similarly, that treatment significantly decreased fresh weight loss percentage compared with the other treatments.

Isolation and identification of polysaccharides from Pythium arrhenomanes and application to strawberry fruit (Fragaria ananassa Duch.) preservation

In this study, we extracted exopolysaccharides from Pythium arrhenomanes and purified them to obtain three polysaccharides (PEPS-1, PEPS-2, PEPS-3). The composition of these polysaccharides was determined. PEPS-2 and PEPS-3 showed outstanding antioxidant activities. PEPS-2 was chosen as a polysaccharide-based coating for strawberry fruit, and its effects on postharvest preservation of the fruit were determined. Strawberries coated with PEPS-2 exhibited significant delay in decay index and lower malondialdehyde, higher soluble solids content, anthocyanin content and vitamin C content, and greater DPPH radical-scavenging activity than uncoated control fruit. The developed method could be beneficial for improving the shelf-life of strawberries.

Influence of carboxy methylcellulose, chitosan and beeswax coatings on cold storage life and quality of Kinnow mandarin fruit

Edible coatings are safer for human health and environment compared to synthetic waxes. The aim of this study was to assess the influence of different edible coatings on extending cold storage life and maintaining fruit quality of ‘Kinnow’ mandarin (Citrus nobilis L. x Citrus deliciosa L.). Kinnow fruit coating treatments included 1.0, 1.5 and 2.0 g L−1 carboxy methylcellulose (CMC), 0.5, 1.0 and 1.5 g L−1 chitosan and 5, 10 and 15 g L−1 beeswax were contrasted to the uncoated (control) fruit. The coated and uncoated fruit were kept under cold storage conditions (5–7 °C and 90–95% RH) up to 75 days. The fruit were sampled following 30, 45, 60 and 75 days cold storage and evaluated for different quality parameters and scanning electron microscopy of the peel surface. The results indicate variability among the different polymer coatings for weight loss, spoilage loss, juice content, firmness, pectin content, the activity of pectin methylesterase and cellulase, soluble solids concentration (SSC), titratable acidity (TA), ascorbic acid content, total carotenoids content and organoleptic sensory attributes. Improved fruit gloss was observed in all coatings treatments, however, with the extension of the cold storage period, the fruit coated with chitosan and beeswax showed outward ruptures on the rind. Amongst all, the coatings tested, CMC (2.0 g L-1) coating was the most effective in maintaining various fruit quality parameters such as SSC, TA, vitamin C, sensory attributes and retarding the activities of cell wall degrading enzymes such as pectin methylesterase and cellulase up to 60 days in cold storage.

Low-Molecular-Weight Dextran Sulfate Nanocapsules Inhibit the Adhesion of Helicobacter pylori to Gastric Cells.

The Gram-negative bacterium Helicobacter pylori is the most common bacterial pathogen in humans, infecting 24-79% of the population at any time. Standard eradication protocols involve multi-target therapy including combinations of antibiotics, which has promoted the emergence of resistant strains. To address this challenge, we prepared antibiotic-free colloidal nanoparticles designed to interfere with the adhesion mechanisms of H. pylori and thus prevent both the onset and recurrence of infection. Our colloidal particles comprised a nanocapsule (NC) formulation based on an oil-core nanoemulsion co-stabilized with lysozyme and lecithin, coated with negatively charged low-molecular-weight (DexS40-NC) or high-molecular-weight (DexS500-NC) dextran sulfate, or positively charged chitosan (CSHMC+30-NC). The oil core of all NC formulations was also loaded with curcumin, a model lipophilic phytochemical substance with well-documented anti-inflammatory and anti-tumor activities. Our proof-of-principle experiments showed that the DexS40-NC formulation inhibited the adhesion of H. pylori to AGS stomach cells in a dose-dependent manner. DexS40-NC achieved more potent inhibition than DexS500-NC or uncoated control nanoemulsions, whereas the effect of CSHMC+30-NC was not clear-cut given the ability of this formulation to aggregate bacteria. DexS40-NC, unlike DexS500-NC, showed no cytotoxic effects against AGS, Caco-2, or MDCK cell lines. DexS40-NC is, therefore, a promising candidate for further development as an alternative or complementary therapy against H. pylori infections.

Candelilla Wax-Based Coatings and Films: Functional and Physicochemical Characterization

Active coatings and films made from pectin, candelilla wax, aloe mucilage, and glycerol were functionalized with an extract rich in polyphenols from Larrea tridentata (Polyphenol Larrea extract: PLE) leaves at different concentrations (320 to 920 ppm). Antimicrobial capacity was evaluated on avocados by the inoculation of spores from phytopathogenic fungi Colletotrichum gloesporioides and Alternaria alternata. Coatings with 920 ppm of PLE presented the major antimicrobial capacity leading to 22.0 ± 0.4% of endocarp damage for C. gloesporioides and 24.5 ± 0.6% for A. alternata when compared to uncoated (control) avocados (44.8 ± 5.0% for C. gloesporioides and 47.9 ± 9.3% for A. alternata). The coating formulation with 920 ppm of PLE, which presents the highest antimicrobial capacity, was chosen for further evaluation and characterized. The coatings were evaluated in terms of stability, charge, pH, viscosity, and density, and some authors reported stability at 7 days. The films were evaluated by scanning electronic microscopy (SEM), X-ray diffraction, Fourier transformed infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and contact angle measurements. The surface topography shows that the presence and increase of PLE concentrations leads to a higher roughness of the films, and by FTIR was possible to observe the effect of the PLE incorporation on the functional groups of the film matrix. Contact angle was not affected by the incorporation of PLE in the films. The developed bioactive coating is effective to control endocarp damage by fungus invasion and thus protect avocados during storage.

Hyaluronic acid-decorated redox-sensitive chitosan micelles for tumor-specific intracellular delivery of gambogic acid.

Introduction: Herein, a hyaluronic acid (HA)-coated redox-sensitive chitosan-based nanoparticle, HA(HECS-ss-OA)/GA, was successfully developed for tumor-specific intracellular rapid delivery of gambogic acid (GA).Materials and methods: The redox-sensitive polymer, HECS-ss-OA, was prepared through a well-controlled synthesis procedure with a satisfactory reproducibility and stable resulted surface properties of the assembled cationic micelles. GA was solubilized into the inner core of HECS-ss-OA micelles, while HA was employed to coat outside HECS-ss-OA/GA for CD44-mediated active targeting along with protection from cation-associated in vivo defects. The desirable redox-sensitivity of HA(HECS-ss-OA)/GA was demonstrated by morphology and particle size changes alongside in vitro drug release of nanoparticles in different simulated reducing environments.Results: The results of flow cytometry and confocal microscopy confirmed the HA-receptor mediated cellular uptake and burst drug release in highly reducing cytosol of HA(HECS-ss-OA)/GA. Consequently, HA(HECS-ss-OA)/GA showed the highest apoptosis induction and cytotoxicity over the non-sensitive (HA(HECS-cc-OA)/GA) and HA un-coated (HECS-ss-OA/GA) controls against A549 NSCLC model both in vitro and in vivo. Furthermore, a diminished systemic cytotoxicity was observed in HA(HECS-ss-OA)/GA treated mice compared with those treated by HA un-coated cationic ones and GA solution.

Effect of bone sialoprotein coating on progression of bone formation in a femoral defect model in rats.

In orthopedic and trauma surgery, calcium phosphate cement (CPC) scaffolds are widely used as substitute for autologous bone grafts. The purpose of this study was to evaluate bone formation in a femoral condyle defect model in rats after scaffold-coating with bioactive bone sialoprotein (BSP). Our hypothesis was that BSP-coating results in additional bone formation. In 20 Wistar rats, defects of 3.0mm diameter were drilled into the lateral femoral condyles of both legs. BSP-coated scaffolds or uncoated control scaffolds were implanted into the defects. After 4 and 8 weeks, five rats of each group were euthanized, respectively. µCT scans and histological analyses were performed. The ratio of bone volume-total volume (BV/TV) was analyzed and histological sections were evaluated. At week four, bone fraction reached 5.2 ± 1.7% in BSP-coated scaffolds and 4.5 ± 3.2% in the control (p = 0.06). While bone fraction of the BSP-group did not change much between week four and eight [week eight: 5.4 ± 3.8% (p = 0.53)], there was a tendency towards an increase in the control [week eight: 7.0 ± 2.2% (p = 0.08)]. No significant difference in bone fraction were observable between BSP-coated and uncoated scaffolds at week eight (p = 0.08). A significant superiority of BSP-coated scaffolds over uncoated scaffolds could not be proven. However, BSP-coating showed a tendency towards improving bone ingrowth in the scaffolds 4 weeks after implantation. This effect was only short-lived: bone growth in the control scaffolds tended to outpace that of the BSP-group at week eight.

Evaluation of biofouling behavior of zwitterionic silane coated reverse osmosis membranes fouled by marine bacteria

Zwitterionic modification of membrane surfaces is a promising approach to decrease membrane biofouling. In this study, biofouling properties of two commercial polyamide (PA) reverse osmosis (RO) desalination membranes coated with zwitterionic sulfobetaine silane compounds including4-(diethyl(3-(trimethoxysilyl)propyl)ammonia)butane-1-sulfonate (EPBS) and 3-(dimethyl(3-(trimethoxysilyl)propyl)ammonia)propane-1-sulfonate (MPPS) were investigated using five different marine bacteria isolated from Bosphorus, Turkey. To mimic the real environment, new marine strains were isolated for the biofouling assay. The biofouling behavior was monitored at different maturation stages of biofouling bacteria on the surfaces of the membranes. In addition, the permeability variation of the coated membranes was analyzed by measuring the flux values before and after the biofouling process compared to the uncoated, control membrane. According to the results, while commercial control RO membranes were highly prone to biofouling, zwitterionic sulfobetaine silane coated membranes showed a strong anti-bacterial effect against the isolated marine biofouling bacteria with significant bio-film adhesion resistance. When the flux value of commercial uncoated control membrane decreased by 38% after biofouling, the flux reduction was 16% and 20% in the EPBS and MPPS coated membranes, respectively.

Dipyridamole Augments Three-Dimensionally Printed Bioactive Ceramic Scaffolds to Regenerate Craniofacial Bone.

Autologous bone grafts remain a standard of care for the reconstruction of large bony defects, but limitations persist. The authors explored the bone regenerative capacity of customized, three-dimensionally printed bioactive ceramic scaffolds with dipyridamole, an adenosine A2A receptor indirect agonist known to enhance bone formation. Critical-size bony defects (10-mm height, 10-mm length, full-thickness) were created at the mandibular rami of rabbits (n = 15). Defects were replaced by a custom-to-defect, three-dimensionally printed bioactive ceramic scaffold composed of β-tricalcium phosphate. Scaffolds were uncoated (control), collagen-coated, or immersed in 100 μM dipyridamole. At 8 weeks, animals were euthanized and the rami retrieved. Bone growth was assessed exclusively within scaffold pores, and evaluated by micro-computed tomography/advanced reconstruction software. Micro-computed tomographic quantification was calculated. Nondecalcified histology was performed. A general linear mixed model was performed to compare group means and 95 percent confidence intervals. Qualitative analysis did not show an inflammatory response. The control and collagen groups (12.3 ± 8.3 percent and 6.9 ± 8.3 percent bone occupancy of free space, respectively) had less bone growth, whereas the most bone growth was in the dipyridamole group (26.9 ± 10.7 percent); the difference was statistically significant (dipyridamole versus control, p < 0.03; dipyridamole versus collagen, p < 0.01 ). There was significantly more residual scaffold material for the collagen group relative to the dipyridamole group (p < 0.015), whereas the control group presented intermediate values (nonsignificant relative to both collagen and dipyridamole). Highly cellular and vascularized intramembranous-like bone healing was observed in all groups. Dipyridamole significantly increased the three-dimensionally printed bioactive ceramic scaffold's ability to regenerate bone in a thin bone defect environment.

(Invited) Electrodeposited POLY(3,4-ETHYLENEDIOXYTHIOPHENE) (PEDOT) for Invasive Recording and Stimulating Neural Electrodes

Neural electrodes are the best medical technique to alleviate the symptoms of neurodegenerative diseases and to explore of our brains. However, their efficiency is limited by several constraints: their small dimensions lead to high impedance and their rigid and metallic nature coupled with the destructive insertion procedure leads to inflammatory responses in the body that further increases the impedance. Conducting polymers are soft and organic materials that possess a mixed electronic-ionic conductivity, and are ideal candidates for biotic-abiotic interfaces. They are regularly used as coatings for neural electrodes due to their enhancement of electrochemical properties and their believed biocompatibility. The dominant technique to deposit conducting polymers on neural microelectrodes is electropolymerization. Extensive work as being performed on the optimization of the parameters of this deposition method. Still, electrodeposited conducting polymers coatings suffer from poor adhesion on most of their substrates. Besides this issue, there is a lack of long-term in vivostudies confronting conducting polymer coatings to electrical stimulation conditions used in medical applications. In this work, we investigated the influence of the processing solvent for electropolymerization on the stability and the adhesion of conducting polymer coatings. After having defined a precise deposition procedure providing us with stable coatings, we investigated the usefulness of these coatings for in vivodeep brain stimulations. Poly(3,4-ethylenedioxithiophene) (PEDOT) was electropolymerized in three different solvent: acetonitrile, propylene carbonate and water, on platinum-iridium microelectrodes. The coated microelectrodes were subjected to different stability tests: sonication, passive ageing, steam sterilization, and electrical stimulations in vitro. We found out that acetonitrile and propylene carbonate provided the most resistant PEDOT coatings. Still, all of PEDOT coatings processed in the different solvents were stable enough to be used in a medical context. We therefore implanted PEDOT-coated stimulating microelectrodes in rats and applied daily stimulation all the while monitoring the impedance of the microelectrodes. We observed that electrical stimulations decreased the impedance of both the PEDOT-coated microelectrodes and the uncoated control microelectrodes. The decrease in impedance was more important for the control microelectrodes than for the PEDOT-coated ones, which questions the relevance of PEDOT coatings for deep brain stimulation purposes and indicates that more work is required to obtain a performant conducting polymer coating for stimulating neural electrodes.

Surface Modification of Carbon Steel With Plasma Chemical Vapor Deposition for Enhancing Corrosion Resistance in CO2/Brine

More and more oil and gas reservoirs are used for commercial carbon-dioxide-enhanced oil recovery (CO2-EOR), resulting in associated CO2 storage that occurs as part of the process. CO2/brine corrosion of oil tube steel that can occur anywhere along the wellbore is a challenging issue faced by the oil and gas industry. In this paper, to enhance their corrosion resistance in CO2/brine, J55 and N80 oil tube steels were coated with trimethylsilane (TMS) with the plasma chemical vapor deposition (PCVD) method. Both atmosphere and vacuum direct-current (DC) discharges were utilized for TMS plasma coatings (TMS-PCs) deposition. X-ray photoelectron spectroscopy (XPS) was used to characterize the coating surface chemistry. It was found that TMS-PCs deposited with vacuum direct current (DC) coatings (VDCPCs) had higher Si- and C-rich composition than atmospheric DC plasma coatings (ADCPCs). The corrosion resistance of samples with or without TMS-PC was evaluated through the weight loss method (WLM) and the 3-D pitting corrosion quantitative evaluation method (3D-PCQEM), which was conducted in CO2/brine with the self-built corrosion-resistant performance evaluation system (CRPES) and a 3-D scanning optical microscope. The results demonstrated that the TMS-PCs can significantly decrease not only the uniform corrosion rate but also the pitting corrosion rate of N80 and J55 oil tube steels. TMS-PCs deposited with VDCPC showed a lower corrosion rate than that of ADCPC. The scanning electron microscopy (SEM) was used to characterize the surface morphology of the samples before and after WLM, and the results indicated less corrosion and pitting corrosion on coated samples than that of uncoated controls. The energy dispersive spectrometer (EDS) was used to characterize the coating surface chemistry before and after WLM, which also indicated that the ferric content of coated samples was higher than that of uncoated controls after WLM. The results obtained in this paper indicate that TMS-PCs may serve as a very promising barrier against the corrosion and pitting corrosion of tube steel in CO2/brine.