Approaches in biotechnological applications of natural polymers

Natural polymers, such as gums and mucilage, are biocompatible, cheap, easily available and non-toxic materials of native origin. These polymers are increasingly preferred over synthetic materials for industrial applications due to their intrinsic properties, as well as they are considered alternative sources of raw materials since they present characteristics of sustainability, biodegradability and biosafety. As definition, gums and mucilages are polysaccharides or complex carbohydrates consisting of one or more monosaccharides or their derivatives linked in bewildering variety of linkages and structures. Natural gums are considered polysaccharides naturally occurring in varieties of plant seeds and exudates, tree or shrub exudates, seaweed extracts, fungi, bacteria, and animal sources. Water-soluble gums, also known as hydrocolloids, are considered exudates and are pathological products; therefore, they do not form a part of cell wall. On the other hand, mucilages are part of cell and physiological products. It is important to highlight that gums represent the largest amounts of polymer materials derived from plants. Gums have enormously large and broad applications in both food and non-food industries, being commonly used as thickening, binding, emulsifying, suspending, stabilizing agents and matrices for drug release in pharmaceutical and cosmetic industries. In the food industry, their gelling properties and the ability to mold edible films and coatings are extensively studied. The use of gums depends on the intrinsic properties that they provide, often at costs below those of synthetic polymers. For upgrading the value of gums, they are being processed into various forms, including the most recent nanomaterials, for various biotechnological applications. Thus, the main natural polymers including galactomannans, cellulose, chitin, agar, carrageenan, alginate, cashew gum, pectin and starch, in addition to the current researches about them are reviewed in this article.. }To the Conselho Nacional de Desenvolvimento Cientfíico e Tecnológico (CNPq) for fellowships (LCBBC and MGCC) and the Coordenação de Aperfeiçoamento de Pessoal de Nvíel Superior (CAPES) (PBSA). This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit, the Project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462) and COMPETE 2020 (POCI-01-0145-FEDER-006684) (JAT)

Effect of a New Method to Simulate Pulpal Pressure on Bond Strength and Nano leakage of Dental Adhesives to Dentin

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Purpose: To evaluate a new method of simulated pulpal pressure in vitro in comparison with the conventional one. Materials and Methods: Four adhesives were analyzed: a three-step etch-and-rinse (Scotchbond Multi-Purpose [SBMP]), a two-step etch-and-rinse (Single Bond 2 [SB]), a two-step self-etching (Clearfil SE Bond [SE]) and a one-step self-etching (Clearfil S3 [S3]) system. Restorations were built up in flat, deep dentin from extracted molars. After two methods of simulated pulpal pressure or no pulpal pressure (control groups), the samples were cut into sticks and submitted to microtensile bond strength (mu TBS) testing and nanoleakage evaluation. Results were analyzed with two-way ANOVA and Tukey's test (p<0.05). Results: In general, statistical analysis of mu TBS showed SBMP>SB=SE>S3. For both methods of simulated pulpal pressure, the mu TBS of SB and S3 was lower than in control groups. For SBMP and SE, the mu TBS remained stable with simulated pulpal pressure. Conventional and experimental methods of simulating pulpal pressure resulted in similar mu TBS (p = 1.00) and nanoleakage patterns. Silver impregnation was higher with SB and S3, especially after simulated pulpal pressure with both methods. Conclusion: The experimental simulated pulpal-pressure method tested here was similar to the conventional method and can be an alternative to it. The simplified adhesives show reduction in bond strength after simulated pulpal pressure. The multistep adhesives have stable bond strengths under simulated pulpal pressure. Therefore, the separate application of hydrophobic resin can achieve resistance to bonding deterioration after hydrostatic pressure.146517524Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Repair Bond Strength in Aged Methacrylate- and Silorane-based Composites

Purpose: To evaluate the tensile bond strength at repaired interfaces of aged dental composites, either dimethacrylate- or silorane-based, when subjected to different surface treatments. Materials and Methods: The composites used were Filtek P60 (methacrylate-based, 3M ESPE) and Filtek P90 (silorane-based, 3M ESPE), of which 50 slabs were stored for 6 months at 37 degrees C. The surface of adhesion was abraded with a 600-grit silicone paper and the slabs repaired with the respective composite, according to the following surface treatment protocols: G1: no treatment; G2: adhesive application; G3: silane + adhesive; G4: sandblasting (Al2O3) + adhesive; G5: sandblasting (Al2O3) + silane + adhesive. After 24-h storage in distilled water at 37 degrees C, tensile bond strength (TBS) was determined in a universal testing machine (Instron 4411) at a crosshead speed of 0.5 mm/min. The original data were submitted to two-way ANOVA and Tukey's test (alpha = 5%). Results: The methacrylate-based composite presented a statistically significantly higher repair potential than did the silorane-based resin (p = 0.0002). Of the surface treatments for the silorane-based composite, aluminum-oxide air abrasion and adhesive (18.5 +/- 3.3MPa) provided higher bond strength than only adhesive application or the control group without surface treatment. For Filtek P60, the control without treatment presented lower repair strength than all other groups with surface treatments, which were statistically similar to each other. The interaction between the factors resin composite and surface treatment was significant (p = 0.002). Conclusion: For aged silorane-based materials, repairs were considered successful after sandblasting (Al2O3) and adhesive application. For methacrylate resin, repair was successful with all surface treatments tested.15544745

Effects of different photo-polymerization protocols on resin-dentine mu TBS, mechanical properties and cross-link density of a nano-filled resin composite

Objectives: To evaluate the effects of four different light-curing protocols on the microtensile bond strength (mu TBS), ultimate tensile strength (UTS), Knoop micro-hardness (KH) and cross-link density (CLD) of a nano-filled resin composite. Methods: Filtek Supreme XT (3M-ESPE) was used for the entire experiments following four light-curing approaches: ST, standard irradiance; HI, high irradiance; PD, pulse delay; SS, soft start. The specimens were submitted to different storage periods (24 h or 6 months), cut into match-sticks and subsequently submitted to mu TBS testing. Hourglass specimens were also prepared for UTS and KH. Cylindrical specimens were prepared for the CLD evaluation after absolute ethanol challenge. The results were statistically analyzed with a two-way ANOVA and Tukey's test (alpha = 0.05). Results: For UTS and KH, continuous irradiance (PD and SS) induced statistically higher results (p 0.05) were observed between 24 h and 6 months storage. The CLD evaluation showed a statistical drop in KH after 24 h of ethanol storage for PD and SS (step-curing protocols) compared to those attained in continuous mode (ST and HI). Conclusion: The soft-start mode may improve the UTS and KH of nano-filled resin composites without compromising the resin-dentine mu TBS. However, both the step-curing protocols may reduce the cross-link density of the composite polymeric network. Clinical significance: High irradiances photo-polymerization may be adequate for direct aesthetic restorations such as veneers and onlays. Meanwhile, the soft start protocol would seem more appropriate for the photo-polymerization of high c-factors class I and II restorations. (c) 2012 Elsevier Ltd. All rights reserved.4010802809Programme Comprehensive Biomedical Research CentreCentre of Excellence in Medical EngineeringWellcome trus

Prolonged Curing Time Reduces the Effects of Simulated Pulpal Pressure on the Bond Strength of One-step Self-etch Adhesives

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)The aim of this study was to evaluate the effects of extended light-curing procedures on the microtensile bond strength (mu TBS) of onestep self-etch adhesives (1-SEAs) submitted to simulated pulpal pressure. Coronal deep-den-tin specimens were bonded using Clearfil S3 Bond (S3), Adper Easy Bond (EB), or G-Bond Plus (GB) following the manufacturers' recommendations and light-cured for 10 seconds or 40 seconds. The dentin-bonded specimens were stored in distilled water for 24 hours without pulpal pressure (control) or submitted to 20 cm H2O simulated pulpal pressure for 24 hours. The specimens were cut into matchsticks and subjected to mu TBS testing. The data were statistically analyzed using the three-way analysis of variance and Tukey's tests (p<0.05). Debonded sticks were investigated through scanning electron microscopy. EB obtained higher bond strengths than GB and S3. However, prolonged light activation (40 seconds) provided higher mu TBS for all adhesives when submitted to pulpal pressure. Conversely, pulpal pressure caused a drop in mu TBS in EB and S3 when light-cured for 10 seconds. A mixed failure mode was mainly attained for the control groups, whereas the specimens submitted to pulpal pressure failed in the adhesive mode. The mu TBS of GB was not affected by pulpal pressure when light-cured for 10 seconds. Adhesive was the most prevalent failure mode, except when light-cured for 40 seconds, which showed predominantly cohesive failure. Extended curing times improved the resistance of 1-SEAs to simulated pulpal pressure.385545554Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Diagnóstico pré-natal da artrogripose múltipla congênita: relato de caso Prenatal diagnosis of arthrogryposis multiplex congenita: a case report

A artrogripose múltipla congênita é caracterizada pela presença, ao nascimento, de múltiplas contraturas articulares. O diagnóstico pré-natal é difícil, existindo poucos relatos na literatura. Baseia-se, especialmente, na combinação de acinesia fetal, posição anormal dos membros, retardo de crescimento intra-uterino e polidrâmnio. Descrevemos um caso de artrogripose múltipla congênita diagnosticado pela ultra-sonografia no terceiro trimestre gestacional. Os principais achados foram a ausência de movimentação fetal, polidrâmnio e concepto com retardo de crescimento intra-uterino, tipo misto, com acentuada diminuição da circunferência abdominal e torácica, implantação baixa dos pavilhões auriculares, micrognatia, flexão contínua dos membros inferiores e superiores, rotação interna dos fêmures e pé torto à direita.<br>Arthrogryposis multiplex congenita is characterized by multiple joint contractures present at birth. Prenatal diagnosis is difficult. There are few reports in the literature. Fetal akinesia, abnormal limb position, intrauterine growth retardation, and polyhydramnios are the main findings of the ultrasonographic diagnosis. The authors describe a case of arthrogryposis multiplex congenita ultrasonographically diagnosed in the third gestational trimester. The main findings were absence of fetal movements, polyhydramnios, symmetrical and non-symmetrical fetal growth retardation with marked decrease of abdominal and thoracic circumference, low-set ears, micrognathia, continuous flexure contracture of limbs, internal rotation of the femur, and clubfoot on the right