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1.
Braz. j. oral sci ; 23: e243158, 2024. ilus
Article in English | LILACS, BBO | ID: biblio-1527026

ABSTRACT

Aim: In recent years, great advances have been made in the use of CAD/CAM to prepare fixed restorations. The marginal and internal fit of these restorations is a principal determinant for their clinical success. In addition, the nature of the oral environment affects the mechanical properties of these restorations. Therefore, this study aimed to investigate the effect of aging process under conditions that simulate the oral environment on the marginal adaptation, and, fracture resistance of crowns fabricated from polyether ether ketone (PEEK) using CAD/CAM methods. Methods: Twenty identical crown restorations were fabricated by using CAD/CAM methods to mill polyether ether ketone (PEEK) material. These crowns were produced by using a software design of an epoxy resin replica of the prepared maxillary first premolar tooth. All PEEK crowns were cemented and randomly divided into two equal groups (A, B). Each group was divided into subgroups (A1, A2 and B1, B2). Group A1 and A2 were used to measure marginal adaptation and fracture resistance, respectively, before aging, while group (B1 and B2) were measured after aging. The cemented crowns were mounted in resin molds to facilitate the sectioning process. The measurements of the marginal gap were performed after sectioning at four points using a stereomicroscope. The fracture resistance of the crowns was investigated using a universal testing machine. A statistical analysis was performed using the GraphPad Prism® software version and unpaired Student's t-test. Results: The results revealed that aging affected the marginal gap, and the fracture resistance of the PEEK crowns. While aging, negatively affected the conditions under investigation, however the least significant difference of marginal gap was found in the margin region. Conclusions: PEEK-CAD/CAM is considered as a good alternative prosthodontic material for fixed prostheses. The CAD/CAM technique used to make PEEK crown restorations in our study offers the advantages of high marginal accuracy and fracture resistance for long-term performance in the oral environment


Subject(s)
Polymers , Aging , Computer-Aided Design , Dental Marginal Adaptation , Crowns , Flexural Strength , Ketones
2.
Actual. osteol ; 19(2): 128-143, sept. 2023. ilus, tab
Article in Spanish | LILACS, UNISALUD, BINACIS | ID: biblio-1523882

ABSTRACT

El presente trabajo muestra la obtención de un material a partir de un polímero sintético (TerP) y otro natural, mediante entrecruzamiento físico y su caracterización fisicoquímica y biológica, con el fin de emplearlos para regeneración de tejido óseo. Las membranas fueron obtenidas por la técnica de evaporación del solvente y caracterizadas por espectroscopia FTIR, ensayos de hinchamiento, medidas de ángulo de contacto y microscopia electrónica de barrido (SEM). Se encontró que la compatibilidad entre los polímeros que la constituyen es estable a pH fisiológico y que, al incorporar mayor cantidad del TerP a la matriz, esta se vuelve más hidrofóbica y porosa. Además, teniendo en cuenta la aplicación prevista para dichos materiales, se realizaron estudios de biocompatibilidad y citotoxicidad con células progenitoras de médula ósea (CPMO) y células RAW264.7, respectivamente. Se evaluó la proliferación celular, la producción y liberación de óxido nítrico (NO) al medio de cultivo durante 24 y 48 horas y la expresión de citoquinas proinflamatorias IL-1ß y TNF-α de las células crecidas sobre los biomateriales variando la cantidad del polímero sintético. Se encontró mayor proliferación celular y menor producción de NO sobre las matrices que contienen menos proporción del TerP, además de poseer una mejor biocompatibilidad. Los resultados de este estudio muestran que el terpolímero obtenido y su combinación con un polímero natural es una estrategia muy interesante para obtener un biomaterial con posibles aplicaciones en medicina regenerativa y que podría extenderse a otros sistemas estructuralmente relacionados. (AU)


In the present work, the preparation of a biomaterial from a synthetic terpolymer (TerP) and a natural polymer, physically crosslinked, is shown. In order to evaluate the new material for bone tissue regeneration, physicochemical and biological characterizations were performed. The membranes were obtained by solvent casting and characterized using FTIR spectroscopy, swelling tests, contact angle measurements, and scanning electron microscopy (SEM). It was found that the compatibility between the polymers is stable at physiological pH and the incorporation of a higher amount of TerP into the matrix increases hydrophobicity and porosity.Furthermore, considering the intended application of these materials, studies of biocompatibility and cytotoxicity were conducted with Bone Marrow Progenitor Cells (BMPCs) and RAW264.7 cells, respectively. Cell proliferation, NO production and release into the culture medium for 24 and 48 hours, and proinflammatory cytokine expression of IL-1ß and TNF-α from cells grown on the biomaterials while varying the amount of the synthetic polymer were evaluated. Greater cell proliferation and lower NO production were found on matrices containing a lower proportion of TerP, in addition to better biocompatibility. The results of this study demonstrate that the obtained terpolymer and its combination with a natural polymer is a highly interesting strategy for biomaterial preparation with potential applications in regenerative medicine. This approach could be extended to other structurally related systems. (AU)


Subject(s)
Animals , Rats , Osteogenesis , Polymers/chemistry , Biocompatible Materials/chemical synthesis , Bone and Bones/chemistry , Bone Regeneration , Chitosan/chemistry , Polymers/toxicity , Biocompatible Materials/toxicity , Materials Testing , Cell Differentiation , Chromatography, Gel , Spectroscopy, Fourier Transform Infrared , Cell Culture Techniques , Nuclear Magnetic Resonance, Biomolecular , Chitosan/toxicity
3.
Chinese Medical Journal ; (24): 322-330, 2023.
Article in English | WPRIM | ID: wpr-970070

ABSTRACT

BACKGROUND@#There are few data comparing clinical outcomes of complex percutaneous coronary intervention (CPCI) when using biodegradable polymer drug-eluting stents (BP-DES) or second-generation durable polymer drug-eluting stents (DP-DES). The purpose of this study was to investigate the safety and efficacy of BP-DES and compare that with DP-DES in patients with and without CPCI during a 5-year follow-up.@*METHODS@#Patients who exclusively underwent BP-DES or DP-DES implantation in 2013 at Fuwai Hospital were consecutively enrolled and stratified into two categories based on CPCI presence or absence. CPCI included at least one of the following features: unprotected left main lesion, ≥2 lesions treated, ≥2 stents implanted, total stent length >40 mm, moderate-to-severe calcified lesion, chronic total occlusion, or bifurcated target lesion. The primary endpoint was major adverse cardiac events (MACE) including all-cause death, recurrent myocardial infarction, and total coronary revascularization (target lesion revascularization, target vessel revascularization [TVR], and non-TVR) during the 5-year follow-up. The secondary endpoint was total coronary revascularization.@*RESULTS@#Among the 7712 patients included, 4882 (63.3%) underwent CPCI. Compared with non-CPCI patients, CPCI patients had higher 2- and 5-year incidences of MACE and total coronary revascularization. Following multivariable adjustment including stent type, CPCI was an independent predictor of MACE (adjusted hazard ratio [aHR]: 1.151; 95% confidence interval [CI]: 1.017-1.303, P  = 0.026) and total coronary revascularization (aHR: 1.199; 95% CI: 1.037-1.388, P  = 0.014) at 5 years. The results were consistent at the 2-year endpoints. In patients with CPCI, BP-DES use was associated with significantly higher MACE rates at 5 years (aHR: 1.256; 95% CI: 1.078-1.462, P  = 0.003) and total coronary revascularization (aHR: 1.257; 95% CI: 1.052-1.502, P  = 0.012) compared with that of DP-DES, but there was a similar risk at 2 years. However, BP-DES had comparable safety and efficacy profiles including MACE and total coronary revascularization compared with DP-DES in patients with non-CPCI at 2 and 5 years.@*CONCLUSIONS@#Patients underwent CPCI remained at a higher risk of mid- to long-term adverse events regardless of the stent type. The effect of BP-DES compared with DP-DES on outcomes was similar in CPCI and non-CPCI patients at 2 years but had inconsistent effects at the 5-year clinical endpoints.


Subject(s)
Humans , Drug-Eluting Stents/adverse effects , Myocardial Infarction/complications , Polymers/therapeutic use , Treatment Outcome , Coronary Artery Disease/complications , Percutaneous Coronary Intervention/adverse effects , Absorbable Implants , Prosthesis Design
4.
Chinese Journal of Biotechnology ; (12): 4445-4462, 2023.
Article in Chinese | WPRIM | ID: wpr-1008035

ABSTRACT

Plastics are widely used in human daily life, which bring great convenience. Nevertheless, the disposal of a large amount of plastic wastes also brings great pressure to the environment. Polyethylene terephthalate (PET) is a polymer thermoplastic material produced from petroleum. It has become one of the most commonly used plastics in the world due to its durability, high transparency, light weight and other characteristics. PET can exist in nature for a long time due to its complex structure and the difficulty in degradation, which causes serious pollution to the global ecological environment, and threatens human health. The degradation of PET wastes has since become one of the global challenges. Compared with physical and chemical methods, biodegradation is the greenest way for treating PET wastes. This review summarizes the recent advances on PET biodegradation including microbial and enzymatic degradation of PET, biodegradation pathway, biodegradation mechanisms, and molecular modification of PET-degrading enzymes. In addition, the prospect for achieveing efficient degradation of PET, searching and improving microorganisms or enzymes that can degrade PET of high crystallinity are presented, with the aimto facilitate the development, application and molecular modification of PET biodegradation microorganisms or enzymes.


Subject(s)
Humans , Polyethylene Terephthalates/metabolism , Polymers , Biodegradation, Environmental , Petroleum
5.
Chinese Medical Journal ; (24): 1848-1854, 2023.
Article in English | WPRIM | ID: wpr-1007585

ABSTRACT

BACKGROUND@#The HELIOS stent is a sirolimus-eluting stent with a biodegradable polymer and titanium oxide film as the tie-layer. The study aimed to evaluate the safety and efficacy of HELIOS stent in a real-world setting.@*METHODS@#The HELIOS registry is a prospective, multicenter, cohort study conducted at 38 centers across China between November 2018 and December 2019. A total of 3060 consecutive patients were enrolled after application of minimal inclusion and exclusion criteria. The primary endpoint was target lesion failure (TLF), defined as a composite of cardiac death, non-fatal target vessel myocardial infarction (MI), and clinically indicated target lesion revascularization (TLR) at 1-year follow-up. Kaplan-Meier methods were used to estimate the cumulative incidence of clinical events and construct survival curves.@*RESULTS@#A total of 2998 (98.0%) patients completed the 1-year follow-up. The 1-year incidence of TLF was 3.10% (94/2998, 95% closed interval: 2.54-3.78%). The rates of cardiac death, non-fatal target vessel MI and clinically indicated TLR were 2.33% (70/2998), 0.20% (6/2998), and 0.70% (21/2998), respectively. The rate of stent thrombosis was 0.33% (10/2998). Age ≥60 years, diabetes mellitus, family history of coronary artery disease, acute myocardial infarction at admission, and device success were independent predictors of TLF at 1 year.@*CONCLUSION@#The 1-year incidence rates of TLF and stent thrombosis were 3.10% and 0.33%, respectively, in patients treated with HELIOS stents. Our results provide clinical evidence for interventional cardiologists and policymakers to evaluate HELIOS stent.@*CLINICAL TRIAL REGISTRATION@#ClinicalTrials.gov, NCT03916432.


Subject(s)
Humans , Middle Aged , Sirolimus/therapeutic use , Drug-Eluting Stents/adverse effects , Prospective Studies , Cohort Studies , Treatment Outcome , Risk Factors , Time Factors , Percutaneous Coronary Intervention/adverse effects , Cardiovascular Agents/therapeutic use , Coronary Artery Disease/therapy , Myocardial Infarction/etiology , Thrombosis/complications , Polymers , Registries
6.
China Journal of Chinese Materia Medica ; (24): 2419-2425, 2023.
Article in Chinese | WPRIM | ID: wpr-981318

ABSTRACT

This study combined the herbal pair Platycodonis Radix-Curcumae Rhizoma(PR-CR) possessing an inhibitory effect on tumor cell proliferation and metastasis with the active component of traditional Chinese medicine(TCM) silibinin-loaded nanoparticles(NPs) with a regulatory effect on tumor microenvironment based on the joint effect on tumor cells and tumor microenvironment to inhi-bit cell metastasis. The effects of PR-CR on the cellular uptake of NPs and in vitro inhibition against breast cancer proliferation and metastasis were investigated to provide an experimental basis for improving nanoparticle absorption and enhancing therapeutic effects. Silibinin-loaded lipid-polymer nanoparticles(LPNs) were prepared by the nanoprecipitation method and characterized by transmission electron microscopy. The NPs were spherical or quasi-spherical in shape with obvious core-shell structure. The mean particle size was 107.4 nm, Zeta potential was-27.53 mV. The cellular uptake assay was performed by in vitro Caco-2/E12 coculture cell model and confocal laser scanning microscopy(CLSM), and the results indicated that PR-CR could promote the uptake of NPs. Further, in situ intestinal absorption assay by the CLSM vertical scanning approach showed that PR-CR could promote the absorption of NPs in the enterocytes of mice. The inhibitory effect of NPs on the proliferation and migration of 4T1 cells was analyzed using 4T1 breast cancer cells and co-cultured 4T1/WML2 cells, respectively. The results of the CCK8 assay showed that PR-CR-containing NPs could enhance the inhibition against the proliferation of 4T1 breast cancer cells. The wound healing assay indicated that PR-CR-containing NPs enhanced the inhibition against the migration of 4T1 breast cancer cells. This study enriches the research on oral absorption of TCM NPs and also provides a new idea for utilizing the advantages of TCM to inhibit breast cancer metastasis.


Subject(s)
Humans , Mice , Animals , Female , Silymarin/therapeutic use , Caco-2 Cells , Polymers/chemistry , Nanoparticles/chemistry , Cell Line, Tumor , Breast Neoplasms/pathology , Tumor Microenvironment
7.
Chinese Journal of Biotechnology ; (12): 2081-2094, 2023.
Article in Chinese | WPRIM | ID: wpr-981191

ABSTRACT

Plastics are one of the most important polymers with huge global demand. However, the downsides of this polymer are that it is difficult to degrade, which causes huge pollution. The environmental-friendly bio-degradable plastics therefore could be an alternative and eventually fulfill the ever-growing demand from every aspect of the society. One of the building blocks of bio-degradable plastics is dicarboxylic acids, which have excellent biodegradability and numerous industrial applications. More importantly, dicarboxylic acid can be biologically synthesized. Herein, this review discusses the recent advance on the biosynthesis routes and metabolic engineering strategies of some of the typical dicarboxylic acids, in hope that it will help to provide inspiration to further efforts on the biosynthesis of dicarboxylic acids.


Subject(s)
Biodegradable Plastics , Dicarboxylic Acids , Polymers/metabolism , Biodegradation, Environmental , Metabolic Engineering
8.
Chinese Journal of Biotechnology ; (12): 1930-1948, 2023.
Article in Chinese | WPRIM | ID: wpr-981180

ABSTRACT

Polyolefin plastics are a group of polymers with C-C backbone that have been widely used in various areas of daily life. Due to their stable chemical properties and poor biodegradability, polyolefin plastic waste continues to accumulate worldwide, causing serious environmental pollution and ecological crises. In recent years, biological degradation of polyolefin plastics has attracted considerable attention. The abundant microbial resources in the nature offer the possibility of biodegradation of polyolefin plastic waste, and microorganisms capable of degrading polyolefin have been reported. This review summarizes the research progress on the biodegradation microbial resources and the biodegradation mechanisms of polyolefin plastics, presents the current challenges in the biodegradation of polyolefin plastics, and provides an outlook on future research directions.


Subject(s)
Plastics/metabolism , Polymers/metabolism , Polyenes , Biodegradation, Environmental
9.
Chinese Journal of Biotechnology ; (12): 1883-1888, 2023.
Article in Chinese | WPRIM | ID: wpr-981177

ABSTRACT

The large scale production and indiscriminate use of plastics led to serious environmental pollution. To reduce the negative effects of plastics waste on the environment, an approach of enzymatic degradation was put forward to catalyze plastics degradation. Protein engineering strategies have been applied to improve the plastics degrading enzyme properties such as activity and thermal stability. In addition, polymer binding modules were found to accelerate the enzymatic degradation of plastics. In this article, we introduced a recent work published in Chem Catalysis, which studied the role of binding modules in enzymatic hydrolysis of poly(ethylene terephthalate) (PET) at high-solids loadings. Graham et al. found that binding modules accelerated PET enzymatic degradation at low PET loading (< 10 wt%) and the enhanced degradation cannot be observed at high PET loading (10 wt%-20 wt%). This work is beneficial for the industrial application of polymer binding modules in plastics degradation.


Subject(s)
Polyethylene Terephthalates/metabolism , Polymers , Plastics , Ethylenes
10.
Chinese Journal of Biotechnology ; (12): 1390-1402, 2023.
Article in Chinese | WPRIM | ID: wpr-981145

ABSTRACT

Polymer nanoparticles generally refer to hydrophobic polymers-based nanoparticles, which have been extensively studied in the nanomedicine field due to their good biocompatibility, efficient long-circulation characteristics, and superior metabolic discharge patterns over other nanoparticles. Existing studies have proved that polymer nanoparticles possess unique advantages in the diagnosis and treatment of cardiovascular diseases, and have been transformed from basic researches to clinical applications, especially in the diagnosis and treatment of atherosclerosis (AS). However, the inflammatory reaction induced by polymer nanoparticles would induce the formation of foam cells and autophagy of macrophages. In addition, the variations in the mechanical microenvironment of cardiovascular diseases may cause the enrichment of polymer nanoparticles. These could possibly promote the occurrence and development of AS. Herein, this review summarized the recent application of polymer nanoparticles in the diagnosis and treatment of AS, as well as the relationship between polymer nanoparticles and AS and the associated mechanism, with the aim to facilitate the development of novel nanodrugs for the treatment of AS.


Subject(s)
Humans , Polymers/chemistry , Cardiovascular Diseases , Nanoparticles/chemistry , Drug Delivery Systems , Atherosclerosis/pathology
11.
Chinese Journal of Biotechnology ; (12): 500-515, 2023.
Article in Chinese | WPRIM | ID: wpr-970388

ABSTRACT

As a widespread pollutant in the environment, research on microplastics have attracted much attention. This review systematically analyzed the interaction between microplastics and soil microorganisms based on existing literatures. Microplastics can change the structure and diversity of soil microbial communities directly or indirectly. The magnitude of these effects depends on the type, dose and shape of microplastics. Meanwhile, soil microorganisms can adapt to the changes caused by microplastics through forming surface biofilm and selecting population. This review also summarized the biodegradation mechanism of microplastics, and explored the factors affecting this process. Microorganisms will firstly colonize the surface of microplastics, and then secrete a variety of extracellular enzymes to function at specific sites, converting polymers into lower polymers or monomers. Finally, the depolymerized small molecules enter the cell for further catabolism. The factors affecting this degradation process are not only the physical and chemical properties of the microplastics, such as molecular weight, density and crystallinity, but also some biological and abiotic factors that affect the growth and metabolism of related microorganisms and the enzymatic activities. Future studies should focus on the connection with the actual environment, and develop new technologies of microplastics biodegradation to solve the problem of microplastic pollution.


Subject(s)
Microplastics , Plastics , Soil , Polymers , Biodegradation, Environmental
12.
Chinese Journal of Medical Instrumentation ; (6): 415-423, 2023.
Article in Chinese | WPRIM | ID: wpr-982256

ABSTRACT

Soft tissue is an indispensable tissue in human body. It plays an important role in protecting the body from external physical, chemical or biological factors. Mild soft tissue injuries can self-heal, while severe soft tissue injuries may require related treatment. Natural polymers (such as chitosan, hyaluronic acid, and collagen) and synthetic polymers (such as polyethylene glycol and polylactic acid) exhibit good biocompatibility, biodegradability and low toxicity. It can be used for soft tissue repairs for antibacterial, hemostatic and wound healing purposes. Their related properties can be enhanced through modification or preparation of composite materials. Commonly used soft tissue repairs include wound dressings, biological patches, medical tissue adhesives, and tissue engineering scaffolds. This study introduces the properties, mechanisms of action and applications of various soft tissue repair medical materials, including chitosan, hyaluronic acid, collagen, polyethylene glycol and polylactic acid, and provides an outlook on the application prospects of soft tissue repair medical materials and products.


Subject(s)
Humans , Biocompatible Materials/chemistry , Chitosan/chemistry , Hyaluronic Acid , Tissue Scaffolds/chemistry , Collagen/chemistry , Polymers/chemistry , Polyethylene Glycols , Soft Tissue Injuries
13.
Acta cir. bras ; 38: e380623, 2023. tab, graf, ilus
Article in English | LILACS, VETINDEX | ID: biblio-1419861

ABSTRACT

Purpose: To evaluate the in vivo efficiency of commercial polymeric membranes for guided bone regeneration. Methods: Rat calvarial critical size defects was treated with LuminaCoat (LC), Surgitime PTFE (SP), GenDerm (GD), Pratix (PR), Techgraft (TG) or control (C-) and histomorphometric analysis determined the percentage of new bone, connective tissue and biomaterial at 1 or 3 months. Statistical analysis used ANOVA with Tukey's post-test for means at same experimental time and the paired Student's t test between the two periods, considering p < 0.05. Results: New bone at 1 month was higher for SP, TG and C-, at 3 months there were no differences, and between 1 and 3 months PR had greater increase growthing. Connective tissue at 1 month was higher for C-, at 3 months for PR, TG and C-, and between 1 and 3 months C- had sharp decline. Biomaterial at 1 month was higher for LC, in 3 months for SP and TG, and between 1 and 3 months, LC, GD and TG had more decreasing mean. Conclusion: SP had greater osteopromotive capacity and limitation of connective ingrowth, but did not exhibit degradation. PR and TG had favorable osteopromotion, LC less connective tissue and GD more accelerated biodegradation.


Subject(s)
Animals , Rats , Polymers/therapeutic use , Skull/abnormalities , Biocompatible Materials/analysis , Bone Regeneration , Collagen , Guided Tissue Regeneration/veterinary
14.
São Paulo; s.n; s.n; 2023. 107 p. tab, graf, ilus.
Thesis in Portuguese | LILACS | ID: biblio-1437843

ABSTRACT

Atualmente a agricultura ocupa um papel de extrema importância na conjuntura global e nacional e está inserida em um contexto de enormes desafios devido ao aumento da população mundial e maior demanda por alimentos. Ao mesmo tempo, é o setor mais afetado pelos impactos negativos das mudanças climáticas, que têm espalhado suas consequências de maneira cada vez mais frequente e intensa. Um dos principais efeitos é a alteração do regime de chuvas ao redor do globo, ocasionando estiagens intensas e duradouras, capazes de reduzir a produtividade de safras e comprometer a produção alimentícia. As abordagens atualmente existentes no mercado para mitigar as consequências negativas da escassez hídrica demandam alto investimento de implementação e manutenção, ou possuem um perfil ecotoxicológico insatisfatório. Polímeros de origem natural modificados quimicamente foram avaliados em termos de desempenho e capacidade de prover às plantas uma maior disponibilidade de água através de retenção hídrica. Os resultados alcançados demonstraram que os polímeros modificados com grupos iônicos foram capazes de promover um melhor gerenciamento hídrico no microambiente ao redor de sementes e entregar ganhos de produtividade a lavouras de soja. O mecanismo de ação da tecnologia estudada foi elucidado através de ensaios de determinação de capacidade de campo, análise de elipsometria, microscopia de força atômica, ensaios de germinação de soja sob estresse hídrico e implementação de áreas de soja a céu aberto a partir da aplicação em tratamento de sementes e sulco de plantio. As interações intra e intermoleculares entre as partículas de solo, moléculas de polímero e de água se mostraram ponto chave para a mudança de patamar de desempenho de polímeros naturais modificados utilizados na agricultura, quando comparados com os grupos controle. A tecnologia aqui estudada é, portanto, recomendada para utilização na agricultura, com capacidade de potencializar o efeito de tecnologias dependentes de água, resultando em maior produtividade na colheita


Nowadays agriculture occupies an extremely important role both in the global and national scenarios. Its included in a very challenging context due to the forecast of increased world population and consequent higher demand for food. At the same time, it is the most affected economic sector by the climate change effects, which have been causing frequent and harsh impacts. One of the main effects is the change in the rainfall pattern worldwide, which causes severe and long-lasting droughts, responsible for causing crops to fail and therefore putting food production at risk. The current available mitigation measures to address hydric scarcity require a huge investment for implementation and maintenance or do not present a satisfactory and safe ecotoxicological profile. Chemically modified natural polymers have been evaluated in terms of performance and ability to provide the plants with higher water availability through hydric retention. The results obtained show that such ionic group modified polymers are able to promote better water management in a given microenvironment surrounding the seeds and ultimately delivery a higher yield to soy crops. The technology's mode of action has been elucidated through field capacity determination trials, ellipsometry, atomic force microscopy, soy germination trials under hydric stress and, finally, implementation of soy areas under actual field conditions by applying the polymers via seed treatment and in-furrow methods. Both intra- and intermolecular interaction between soil particles, polymer and water molecules have been proven as key to understanding the agricultural performance improvement of the modified polymers when compared to the control. The technology is recommended for agricultural applications due to its ability to boost the effect of water-dependent technologies, promoting higher yields


Subject(s)
Polymers/analysis , Dehydration/complications , Agriculture/classification , Polysaccharides/adverse effects , Soil , Glycine max/growth & development , Water , Efficiency/classification , Food/classification
15.
Biosci. j. (Online) ; 39: e39009, 2023. tab, graf
Article in English | LILACS | ID: biblio-1415877

ABSTRACT

1,4-alpha-D-glucan glucanohydrolase is among the most widely used commercial hydrolytic enzymes acting randomly on the glycosidic linkages of starch resulting in its saccharification and liquefaction. Its applicability in different industries can be improved by enhancing its stability and reusability. Therefore, in the present study attempts have been made to enhance the industrial applicability of 1,4-alpha-D-glucan glucanohydrolase from Bacillus subtilis KIBGE-HAR by adapting immobilization technology. The study developed mechanically stable, enzyme containing gel-frameworks using two support matrices including agar-agar, a natural polysaccharide and polyacrylamide gel, a synthetic organic polymer. These catalytic gel-scaffolds were compared with each other in terms of kinetics and stability of entrapped 1,4-α-D-glucan glucanohydrolase. In case of polyacrylamide gel, Km value for immobilized enzyme increased to 7.95 mg/mL, while immobilization in agar-agar resulted in decreased Km value i.e 0.277 mg/mL as compared to free enzyme. It was found that immobilized enzyme showed maximum activity at 70 °C in both the supports as compared to free enzyme having maximum activity at 60 °C. Immobilized 1,4-α-D-glucan glucanohydrolase exhibited no change in optimal pH 7.0 before and after entrapment in polyacrylamide gel and agar-agar. The enzyme containing gel-scaffold was found suitable for repeated batches of starch liquefaction in industrial processes. Agar-agar entrapped 1,4-α-D-glucanglucanohydrolase was capable to degrade starch up to seven repeated operational cycles whereas polyacrylamide entrapped enzyme conserved its activity up to sixth operational cycle.


Subject(s)
Polymers , Kinetics , Amylases
16.
Braz. dent. sci ; 26(4): 1-10, 2023. ilus, tab
Article in English | BBO, LILACS | ID: biblio-1516476

ABSTRACT

Objective: to evaluate the effect of material type and veneer thickness on the final color and shear bond strength of PEEK bilayered restorations. Material and Methods: sixty-four square-shaped core specimens (7×7×2), were fabricated by CAD/CAM technology from two high-strength polymers, BioHPP (High-Performance Polymer, group B n=32), and Pekkton® ivory (PolyEtherKetoneKetone, group P n=32) then were veneered with resin composite (crea.lign dentin A3). Specimens from each group were divided (n=16) according to the veneer layer thickness (0.5 & 1 mm), then according to the test applied (n=8), either ΔE or shear bond strength (SBS). Specimen surfaces were treated according to the manufacturer's instructions. Specimens were veneered according to the manufacturer's instructions.The mode of failure was evaluated under a stereomicroscope at 40 x magnification after the shear bond strength test. Results: data showed parametric distribution and variance homogeneity and were analyzed using two-way ANOVA. The significance level was set at p<0.05 for all tests. Statistical analysis was performed with the R statistical analysis software version 4.3.1.Results of two-way ANOVA showed that material types and veneer thicknesses had an individual significant effect on the color change. For the shear bond strength, only the sample thickness (1mm) had a significant effect (p=0.033). The majority of samples in different groups presented a mixed failure mode with all the differences being not statistically significant (p>0.05). Conclusion: the thickness of the resin composite veneer can significantly affect the final esthetic outcome and shear bond strength of a bilayered restoration.(AU)


Objetivo: avaliar o efeito do tipo de material e da espessura do revestimento na cor final e na resistência ao cisalhamento de restaurações em duas camadas de PEEK. Material e Métodos: foram fabricados 64 espécimes com núcleo de formato quadrado (7x7x2) usando tecnologia CAD/CAM a partir de dois polímeros de alta resistência, BioHPP (Polímero de Alto Desempenho, grupo B n=32) e Pekkton ivory (Polieterecetona cetona, grupo P n=32), que foram então revestidos com resina composta (crea.lign dentin A3). Os espécimes de cada grupo foram divididos (n=16) de acordo com a espessura do revestimento (0,5 e 1 mm), e depois de acordo com o teste aplicado (n=8), seja ΔE ou resistência ao cisalhamento (SBS). As superfícies dos espécimes foram tratadas de acordo com as instruções do fabricante. Os espécimes foram revestidos de acordo com as instruções do fabricante. O modo de falha foi avaliado sob um estereomicroscópio com ampliação de 40x após o teste de resistência ao cisalhamento. Resultados: os dados apresentaram distribuição paramétrica e homogeneidade de variância e foram analisados por ANOVA de duas vias. O nível de significância foi estabelecido em p<0,05 para todos os testes. A análise estatística foi realizada com o software de análise estatística R, versão 4.3.1. Os resultados da ANOVA de duas vias mostraram que os tipos de materiais e as espessuras do revestimento tiveram um efeito significativo individual na mudança de cor. Para a resistência ao cisalhamento, apenas a espessura da amostra (1mm) teve um efeito significativo (p=0,033). A maioria das amostras em diferentes grupos apresentou um modo de falha misto, com todas as diferenças não sendo estatisticamente significativas (p>0,05). Conclusão:a espessura do revestimento de resina composta pode afetar significativamente o resultado estético final e a resistência ao cisalhamento de uma restauração em duas camadas.(AU)


Subject(s)
Polymers , Composite Resins , Shear Strength
17.
Braz. J. Pharm. Sci. (Online) ; 59: e22320, 2023. tab, graf
Article in English | LILACS | ID: biblio-1439541

ABSTRACT

Abstract Flaxseed (Linum usitatissimum L.) is the seed of a multipurpose plant of pharmaceutical interest, as its mucilage can be used as a natural matrix to develop extended-release dosage forms and potentially replace synthetic polymers. In this study, a 3² factorial design with two replicates of the central point was applied to optimize the development of extended-release granules of metformin HCl. The total fiber content of the mucilage as well as the friability and dissolution of the formulations were evaluated. The lyophilized mucilage presented a high total fiber content (42.63%), which suggests a high efficiency extraction process. Higher concentrations of the mucilage and metformin HCl yielded less friable granules. In addition, lower concentrations of metformin HCl and higher concentrations of the mucilage resulted in slower drug release during the dissolution assays. The release kinetics for most formulations were better represented by the Hixson-Crowell model, while formulations containing a higher concentration of the mucilage were represented by the Korsmeyer-Peppas model. Nonetheless, five formulations showed a longer release than the reference HPMC formulation. More desirable results were obtained with a higher concentration of the mucilage (13-18%) and a lower concentration of metformin (40%).


Subject(s)
Flax/classification , Plant Mucilage/agonists , Metformin/analysis , Plants/adverse effects , Polymers/adverse effects , Pharmaceutical Preparations/analysis
18.
Braz. j. oral sci ; 22: e230130, Jan.-Dec. 2023. ilus
Article in English | LILACS, BBO | ID: biblio-1442841

ABSTRACT

Aim: This study assessed the effect of thermal aging on the interfacial strength of resin cements to surface-treated PEEK. Methods: Ninety-six PEEK blocks were allocated into 4 groups (n=24), according to following surface treatments: SB - sandblasting with aluminum oxide; SA - acid etched with 98% sulfuric acid; CA ­ coupling agent (Visio.link, Bredent) and CO - control group (untreated). Surface roughness (Ra) was measured and one cylinder (1-mm diameter and height) of Rely-X Ultimate - ULT (3M/ESPE) and another one of Panavia V5 - PAN (Kuraray) were constructed on the treated or untreated PEEK surfaces. Half of the samples of each group were thermal aged (1,000 cycles). Samples were tested at a crosshead speed of 1 mm/min in shear mode (µSBS). Ra and µSBS data were compared using one- and three-way ANOVA, respectively, and Tukey's tests. Results: SA and SB samples had the roughest surfaces, while CA the smoother (p<0.001). Thermal aging reduced µSBS regardless the surface treatment and resin cement used. There was interaction between surface treatment and resin cement (p <0.001), with ULT showing higher µSBS values than PAN. SA provided higher µSBS than SB for both resin cements, while for CA µSBS was higher (PAN) or lower than SB (ULT). Conclusion: Aging inadvertently reduces interfacial strength between PEEK and the resin cements. If ULT is the resin cement of choice, reliable interfacial strength is reached after any PEEK surface treatment. However, if PAN is going to be used only SA and CA are recommended as PEEK treatment


Subject(s)
Polymers , Aging , Resin Cements , Shear Strength
19.
Arq. ciências saúde UNIPAR ; 26(3): 1053-1067, set-dez. 2022.
Article in Portuguese | LILACS | ID: biblio-1414345

ABSTRACT

feridas correspondem a interrupção da continuidade da pele, com a perda de uma ou mais camadas do tecido cutâneo. Curativos tradicionalmente aplicados em feridas cutâneas buscam principalmente fornecer uma barreira de proteção e permitir o desenvolvimento dos eventos celulares e bioquímicos que compreendem a cicatrização. Objetivou-se com este estudo apresentar sob a forma de revisão de literatura narrativa os principais eventos relacionados ao processo de reparo tecidual da pele, bem como abordar a aplicabilidade da técnica de eletrofiação no desenvolvimento de curativos funcionais biocompatíveis. Foram selecionados artigos voltados à caracterização dos eventos chave ocorridos a nível tecidual durante a cicatrização e, na sequência, buscou-se artigos voltados à produção, caracterização e aplicação de filmes nanoeletrofiados com ênfase na utilização de biopolímeros e substâncias bioativas. Observou-se que a maioria dos trabalhos recentes, voltados a pesquisa de base, descrevem a resposta vascular como o principal evento do processo cicatricial, sendo responsável pelas etapas que se desenrolam a seguir, que compreendem as fases inflamatória, proliferativa e de remodelamento, classicamente já descritas. Os curativos funcionais baseados em polímeros eletrofiados apresentam resultados superiores quanto testados in vitro e in vivo. As características morfoestruturais mimetizam a matriz extracelular e podem atuar em tecidos alvo como dispositivos de entrega de substâncias. Conclui-se que a atualização e reorganização de conceitos relativos à cicatrização podem contribuir no desenvolvimento de inovações, como os curativos produzidos por eletrofiação. Embora promissora, as desvantagens da técnica encontram-se principalmente no processo de obtenção e disponibilidade, que limitam a aplicação clínica em escala comercial.


Wounds correspond to the interruption of skin continuity, with the loss of one or more layers of skin tissue. Dressings traditionally applied to cutaneous wounds mainly seek to provide a protective barrier and allow the development of cellular and biochemical events that comprise healing. The objective of this study was to present, in the form of a narrative literature review, the main events related to the skin tissue repair process, as well as to address the applicability of the electrospinning technique in the development of biocompatible functional dressings. Articles focused on the characterization of the key events that occurred at the tissue level during healing were selected and, subsequently, articles focused on the production, characterization and application of nanoelectrospun films with emphasis on the use of biopolymers and bioactive substances were sought. It was observed that most recent works, focused on basic research, describe the vascular response as the main event of the healing process, being responsible for the steps that follow, which include the inflammatory, proliferative and remodeling phases, classically already described. Functional dressings based on electrospun polymers show superior results when tested in vitro and in vivo. The morphostructural features mimic the extracellular matrix and can act in target tissues as substance delivery devices. It is concluded that the updating and reorganization of concepts related to healing can contribute to the development of innovations, such as dressings produced by electrospinning. Although promising, the technique's disadvantages lie mainly in the process of obtaining and availability, which limit clinical application on a commercial scale.


Las heridas corresponden a la interrupción de la continuidad de la piel, con la pérdida de una o más capas de tejido cutáneo. Los apósitos aplicados tradicionalmente a las heridas cutáneas buscan principalmente proporcionar una barrera protectora y permitir el desarrollo de los eventos celulares y bioquímicos que comprenden la curación. El objetivo de este estudio fue presentar en forma de revisión bibliográfica narrativa los principales acontecimientos relacionados con el proceso de reparación tisular de la piel, así como abordar la aplicabilidad de la técnica de electrodeposición en el desarrollo de apósitos funcionales biocompatibles. Se seleccionaron artículos dirigidos a la caracterización de los eventos chave ocurridos a nivel técnico durante la cicatrización y, a continuación, se buscaron artículos dirigidos a la producción, caracterización y aplicación de películas nanoelectrofíricas con énfasis en el uso de biopolímeros y sustancias bioativas. Se observa que la mayoría de los trabajos recientes, realizados en la investigación de base, describen la respuesta vascular como el principal evento del proceso cicatricial, siendo responsable de las etapas que se desarrollan a continuación, que comprenden las fases inflamatoria, proliferativa y de remodelación, clásicamente descritas. Los apósitos funcionales basados en polímeros electro-tejidos presentan resultados superiores cuando se prueban in vitro e in vivo. Las características morfoestruturales mimetizan la matriz extracelular y pueden actuar en tejidos alvos como dispositivos de entrega de sustancias. Se concluye que la actualización y la reorganización de los conceptos relativos a la cicatrización pueden contribuir al desarrollo de innovaciones, como las curativas producidas por la electrofagia. Aunque es prometedora, las desventajas de la técnica radican principalmente en el proceso de obtención y la disponibilidad, que limitan la aplicación clínica a escala comercial.


Subject(s)
Polymers/therapeutic use , Bandages , Wound Healing , Wounds and Injuries/drug therapy , Plants, Medicinal/chemistry , Biopolymers/therapeutic use , Review Literature as Topic , Nanofibers/therapeutic use
20.
Odovtos (En línea) ; 24(2)ago. 2022.
Article in English | LILACS, SaludCR | ID: biblio-1386595

ABSTRACT

Abstract The aim of this in vitro study was to compare the long-term effect of overnight use of denture cleansers with different chemical compositions on the color stability of denture base polymers (DBPs). The four DBPs evaluated were PEEK (PK group), thermoinjection-molded polyamide (PA group), auto-polymerized polymethylmethacrylate (PMMA) (AP group), and heat-polymerized resin PMMA (HP group). The cleaning agents used were Corega tablet (CT), Protefix tablet (PT), and 0.5% sodium hypochlorite (NaOCl) solution (SH). Distilled water (DW) served as a control. Forty-eight disc-shaped specimens (10mm × 2mm) were prepared from each DBP and randomly immersed in the different storage media (n=12 in each group). Color measurements of the specimens before and after immersion in the denture cleansers were made using a spectrophotometer (VITA Easyshade V). The color changes were measured and recorded in L* a* b*. After 120 d, the CIEDE2000 formula was used to calculate color changes (ΔE00). For analysis of the data, a multivariate analysis of variance was used (p<0.05). The results of the statistical analysis revealed significant color change differences in the DBPs immersed in the various denture cleansers (p<0.05). Groups PA and PK showed the highest values for all solutions. AP-SH showed the highest ΔE00 value in group AP, no significant difference was found between other solutions. In group HP, there was no statistically significant difference between the average ΔE00 values of all solutions. Long-term daily use of the denture cleansers affected the color stability of all the DBPs, although the level of color change was acceptable. Laboratory and clinical studies on the color stability of PEEK are needed to confirm the results of this study.


Resumen El objetivo de este estudio in vitro fue comparar el efecto a largo plazo del uso nocturno de limpiadores de prótesis con diferentes composiciones químicas sobre la estabilidad del color de los polímeros base de prótesis (DBP). Los cuatro DBP evaluados fueron PEEK (grupo PK), poliamida moldeada por termoinyección (grupo PA), polimetilmetacrilato (PMMA) autopolimerizado (grupo AP) y resina PMMA termopolimerizada (grupo HP). Los agentes de limpieza utilizados fueron Corega (CT), Protefix (PT) y la solución de hipoclorito de sodio (NaOCl) al 0,5% (SH). El agua destilada (DW) sirvió de control. Se prepararon 48 especímenes en forma de disco (10mm × 2mm) de cada DBP y se sumergieron al azar en los diferentes medios de almacenamiento (n=12 en cada grupo). Las mediciones del color de las muestras antes y después de la inmersión en los limpiadores de dentaduras se realizaron con un espectrofotómetro (VITA Easyshade V). Los cambios de color se midieron y registraron en L* a* b*. Después de 120 d, se utilizó la fórmula CIEDE2000 para calcular los cambios de color (ΔE00). Para el análisis de los datos, se utilizó un análisis multivariante de la varianza (p<0,05). Los resultados del análisis estadístico revelaron diferencias significativas en el cambio de color de los DBP sumergidos en los distintos limpiadores de dentaduras (p<0,05). Los grupos PA y PK mostraron los valores más altos para todas las soluciones. AP-SH mostró el valor ΔE00 más alto en el grupo AP, no se encontraron diferencias significativas entre las demás soluciones. En el grupo HP, no hubo diferencias estadísticamente significativas entre los valores medios de ΔE00 de todas las soluciones. El uso diario a largo plazo de los limpiadores de dentaduras afectó a la estabilidad del color de todos los DBP, aunque el nivel de cambio de color fue aceptable. Se necesitan estudios de laboratorio y clínicos sobre la estabilidad del color del PEEK para confirmar los resultados de este estudio.


Subject(s)
Polymers , Prosthesis Coloring , Denture Cleansers , Polymethyl Methacrylate
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