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Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) is a biodegradable, biocompatible, and non-toxic biopolymer. The biopolymer properties can be improved using cellulosic-based materials, often derived from agro-industrial residues, and promoting reuse/re-significance of a by-product for bone tissue engineering applications. Biocomposites of PHBV filled with bleached fibers of palm residues (BFPR) (0–10 % wt/wt) for 3D-printing were prepared. The scaffolds were obtained by additive manufacturing (fused deposition modeling (FDM)). The samples were characterized by stereomicroscopy, SEM, TGA, nanohardness, wettability, FTIR, and biocompatibility. Biocomposites filaments revealed homogeneous diameters, suitable for FDM. Composite filaments had thermal stability at 100–250 °C (processing did not degrade the material). The -OH groups of cellulose (enhanced by bleaching treatment) BFPR added to PHBV had advantages: optimal cell viability, wettability improvement, and slight nanohardness increase. PHBV/BFPR1 % scaffolds had an interconnected porous structure with a pore size of ~900 µm and 60 % filling.

The use of systems based on biodegradable polymers and nanoparticles has shown to be promising to bone tissue engineering. The combination of these materials aims to obtain systems with biological and mechanical suitable properties. The objective of the present paper was to obtain systems composed of polylactide with silver and titanium oxide nanoparticles alone and in binary systems. The systems obtained were characterized by infrared with Fourier transform, X-ray diffraction, thermogravimetric analysis, differentiated scanning calorimetry, relaxometry, cytotoxicity in L929 fibroblast, nanoindentation, wettability, and calcium and phosphate deposition. The titanium nanoparticles did not have a strong influence on the material's crystallinity. On the other hand, the silver nanoparticles acted as a nucleating agent in its lowest concentration, but it led to a decrease in crystallinity in the highest concentrations. The nanoparticles provoked antagonistic effects on the wettability: titanium caused a decrease, while silver led to an increase. The effect generated by silver was predominant in the binary systems. The cell viability test confirmed that all systems obtained are biocompatible. At large, the two particles' application simultaneously produced an increase in the deposition of phosphate calcium and in the nanohardness.

This work deals with the thermodynamic selective localization of hydroxyapatite nanoparticles (Hap) and its effects on crystallization and molecular dynamics in immiscible polyester blend films based on poly(3-hydroxybutyrate) (PHB, 90 wt%) and polycaprolactone (PCL, 10 wt%). Polymer blend composite films were obtained through solution casting method and characterized by contact angle (surface energy measurements), ultraviolet–visible spectroscopy (UV–Vis), elemental mapping, X-ray diffraction (WAXD), differential scanning calorimetry (DSC), polarized optical microscopy (POM) and time domain nuclear magnetic resonance (TD-NMR) techniques. It was found that hydroxyapatite (Hap) is selectively localized in the PHB phase and consequently, nanoparticles strongly influenced the PHB crystallization behavior. DSC and POM results indicated that hydroxyapatite nanoparticles acted as a nucleating agent. However, no significant changes in crystallinity degree were observed by WAXD. Fractionated crystallization behavior was observed for PCL droplets and the increase in the Hap concentration promoted heterogeneous nucleation on the droplets surface due to the nanoparticles close to the interface. Molecular dynamics studies by TD-NMR suggested a disordered Hap nanoparticles distribution inside the polymer matrix, leading to slower dynamics in the semirigid fraction of the sample´s magnetization, typically attributed to restricted polymeric chains close to the particle’s surface.

The development of new materials for obtaining ophthalmic lenses is a subject of great interest due to the great necessity of corrective lenses uses. The application of the lenses based on polymeric material that guarantees greater lightness and less risk of breakage, ensuring greater comfort to users of glasses. The use of nanoparticles in polymer nanocomposites can generate different properties in the final material, mainly when used in hybrid systems in which synergistic effects can be produced. Thus, the present work aimed to evaluate the optical properties of systems with poly(methyl methacrylate) and oxide nanoparticles (silica, zinc, zirconium, and titanium). The systems were characterized in terms of their optical behaviors (refractive index, transmittance, and color change) and mechanical behaviors (nanoindentation, and tensile strength). The results showed that silica-based systems tended to have greater transparency but generate lower refractive indexes. Systems containing zirconia, titanium, and zinc have a higher refractive index and smaller transparency than systems containing silica. Besides, the use of zirconia and titanium increases the nano-hardness and elastic modulus. The results showed that the use of these nanoparticles in binary systems leads to obtaining materials with higher refractive index, greater transparency, and best mechanical behavior. The combination of the nanoparticles also led to a better dispersion, reducing the impact on the color system and improve transparency. In this way, the materials developed using small amounts of fillers and present highly promising for the development of thinner, more resistant to scratching due to high hardness and higher transparent lenses.

Due to the high demand of the use of food packaging in the present day, the waste from the material disposal has become a problem of high environmental impact. In this perspective, biodegradable polymers can represent a viable alternative as they degrade after their disposal, thus reducing their environmental impact. The poly(lactic acid) or polylactide is a biodegradable, biocompatible, and compostable polymer, being considered by many authors as one of the most promising biopolymers in industrial applications. However, its low thermal and mechanical properties make it an unfeasible option to replace synthetic polymers. Consequently, polymer nanocomposites containing carbon nanoparticles are products of relevant interest currently, mainly due to the thermal, mechanical, electrical, and optical properties these materials can present. Therefore, carbon nanoparticles (carbon nanotubes, graphene, and fullerene) modified with octadecylamine in their isolated state and in ternary systems in concentrations of 0.01%, 0.03%, and 0.09% were obtained from poly(lactic acid) polymer nanocomposites. After obtaining them, these systems were analyzed by TGA, DSC, FTIR, XRD, SEM, DMA, and NMR techniques. The presence of the octadecylamine modified carbon nanoparticles was able to increase the thermal and mechanical resistance of the poly(lactic acid) matrix. The systems with 0.03% of the nanostructures showed better results in both analyses. In the system with 0.09%, agglomeration occurred, and in ternary systems, the application of these particles results in a greater impact on the molecular mobility exhibiting a synergistic effect that may come from a better dispersion.

The skin is the most extensive and outermost organ in the body and can be greatly exploited both from the point of view of alternative routes of systemic drug delivery and treatment of dermatological diseases. Because of its main function as a barrier against harmful external agents, it also becomes a barrier to drug administration, but there are strategies to reduce this limitation of this promising route of administration. The development of polymer-based film-forming formulations is extensively studied for this purpose, since the formation of a film on the skin increases the contact time of the drug, for this being characterized as a controlled release reservoir system. There are a multitude of possible polymers to compose these formulations and their choice must be made according to the purpose of each application. This work, therefore, aims to study the state of the art of film forming systems for topical application of pharmaceutical formulations.

Most of the synthetic polymers that are used for packaging industry come from fossil fuel; thus, when their life cycle is complete, they normally accumulate in the environment. The poly(3-hydroxybutyrate) is a biopolymer produced from bacteria; due to its microbial degradation, great attention has been paid to its research; nevertheless, it has been found to be necessary to improve its mechanical, thermal and barrier properties. One of the approaches to do so is the incorporation of inorganic compounds. Zirconium oxide (ZrO2) and zirconium hydroxide (Zr(OH)4) have outstanding thermal stability and are potential compounds for the improvement in PHB features. Along this study, hybrid films made of PHB with 0.01, 0.05 and 0.1 mass% of ZrO2 and Zr(OH)4 were produced; their properties were evaluated by TG and DSC, which permitted to observe that all the composites have improved thermal resistance; furthermore, 0.01 and 0.05% Zr(OH)4 showed lower Wc. These results suggest that zirconium-based PHB composites can increase the process temperature range, which opens the new door to future applications on food packaging.

The purpose of this work was to obtain and characterize curcuminoids loaded nanoparticles based on polycaprolactone and poloxamer whose pharmaceutical applicability justifies its relevance since polyphenolic compounds carriers have anti-inflammatory, antioxidant, antitumor and anti-amyloid potential. The curcuminoids’ extracts (CUR) were obtained from Turmeric (Curcuma longa Linn.) using acetone as organic solvent. Its chemical characterization was done by Fourier transform infrared spectroscopy (FTIR), high-performance liquid chromatography (HPLC) and chiefly by nuclear magnetic resonance (NMR). The polymeric nanoparticles (NPs) were prepared by nanoprecipitation, maintaining all reaction parameters, except for the amount of CUR incorporated in the polycaprolactone (PCL) matrix, which was, respectively, 0%, 5%, 10%, 15% and 20% (percentage in relation to PCL mass) in samples here called 0, 5, 10, 15 and 20. The obtained NPs were analyzed in suspension for size study (by dynamic light scattering—DLS), zeta potential (ZP) and color change, and in powder form, after freeze-drying, for structural study of molecular mobility (by TD-NMR), Scanning electron microscopy (SEM), encapsulation efficiency, and elucidation of composition and incorporation of the extract (by NMR and FTIR). It was possible to obtain very stable spherical CUR-NPs, of size within the nanometric scale, even after 3 months of storage. The desirable surface charge and size for biomedical applications were not effectively hampered by lyophilization as well. After nanoprecipitation there was no degradation of the CUR or chemical interaction with the polymers, which is fundamental for the maintenance, enhancement and viability of its properties. Evaluating the structural NPs’ properties, cost–benefit and possible system saturation, samples 15 and 20 demonstrated excess CUR. The methods used for both extraction and encapsulation proved to be efficient, reproducible, practical and inexpensive, which is very advantageous for a potential scaling and use of CUR-NPs in the pharmaceutical industry.

Introduction: To evaluate the influence of a fluoride mouthwash containing nano-hydroxyapatite on the dentin bonding interface microhardness of direct resin composite restorations in situ. Methodology: Forty human premolars were sectioned and restored with a three-step adhesive system or a self-etch adhesive system and a conventional resin-based composite. After the initial microhardness measurements on the samples’ dentin interface, the restored samples were fixed in acrylic palate appliances for an in situ experiment. Ten volunteers participated in a randomized double-blinded crossover study using the palate appliances and a placebo fluoride mouthwash for one week, one-week wash-out, and one-week fluoride mouthwash containing nanohydroxy-apatite. The final microhardness measurements were evaluated, and data were analyzed by ANOVA and Tukey’s test submitted for multiple comparisons (α = 0.05; 0.8 power). Results: There were statistically significant differences between the mouthwash treatments with both adhesive systems tested (p < 0.001). The nanohydroxyapatite used in the mouthwash was an influencing factor on the dentin interface microhardness of resin composite restorations. Conclusion: The fluoride mouthwash containing the nanohydroxyapatite was able to increase the dentin microhardness of the direct resin composite restorations regardless of the adhesive system used.

Introduction: In order to satisfy the aesthetic desires of the population, by masking the restorations was the search for the evolution of restorative materials enabling the introduction of metal-free materials. But previous studies that have been made with metal structures often cannot be removed and therefore require devices that can be masked, because there is no desire for a total passage of light avoiding dim reflection of these funds. For these situations, you must opt for a ceramic system to provide a degree of opacity, without losing its characteristics of light transmission, reflectance and saturation. Case report: In case the patient had clinical a metal ceramic crown on the molten core element 21, it was confirmed radiographically the core could not be removed because it would fracture risk to the tooth. We chose to use an opaquer ceramic framework to prevent the passage of light over dark metal. The material of choice was zirconia ceramic by high flexural strength, allowing it to function as a framework for crowns. Conclusion: With the correct application of ceramic coverage on Caquetá noted that it is possible to mask the gray color of the metal through the knowledge of the optical material, the correct use of these properties, opacity and translucidus, and a close contact between dentists and prosthetic. Introdução: A fim de satisfazer os anseios estéticos, da população, por mascarar as restaurações houve a busca pela evolução dos materiais restauradores possibilitando a introdução de materiais livres de metais. Porém trabalhos prévios que foram confeccionados com estruturas metálicas muitas vezes não podem ser removidos e, portanto, necessitam de artifícios para que possam ser mascarados, pois não há o desejo de uma total passagem de luz evitando a reflexão desses fundos escurecidos. Para estas situações, é necessário optar por um sistema cerâmico que apresente um grau de opacidade, sem perda de suas características de translucidez, refletância e saturação. Relato do caso: A paciente possuía uma coroa metalo-cerâmica sobre núcleo fundido no elemento 21, constatou-se radiograficamente que o núcleo não podia ser retirado, pois traria risco de fratura ao dente. Optou-se por utilizar uma cerâmica mais opaca de arcabouço para evitar a passagem de luz sobre o metal escurecido. O material de escolha foi à cerâmica de zircônia por apresentar alta resistência à flexão, permitindo que funcione como arcabouço para coroas unitárias. Conclusão: Com a correta aplicação de cerâmicas de cobertura sobre o casquete observou- se que é possível mascarar a cor acinzentada do metal através dos conhecimentos ópticos do material, a correta utilização dessas propriedades, opacidade e translucides, e um estreito contato entre dentista e protético.

After the Fundao iron ore mining dam rupture in November 2015, yellow/ocher emulsions never before reported on the continental shelf adjacent to the Doce River began to be seen, both in coalesced and foam forms. XRD analyses pointed to a prevailing composition of iron and kaolinite with a substantial contribution of an organic-metallic compound, measured in multiple periods over 2 years of sampling. Optical microscopy images allowed the identification of micelles composed of nanoparticles of iron oxyhydroxide making up this emulsion. The generation of dendritic snowflake-shaped microcrystals on fiber filters after water sample filtration and heating confirmed the presence of micelles composed of iron oxyhydroxide nanoparticles enveloped by organic polymers. After losing water, the micelles may act as a self-assembly template seed, where the polymer acts in the oriented adsorption of nanoparticles according to their crystallographic structure. The study brought to light the distinct behavior of a portion of the tailings material, which has already been reported to not have the same flocculation process as the clay minerals previously found in the suspended particulate material (SPM) before the dam rupture.

Carbon nanostructures have been extensively studied due to combination of properties they present. With different geometries and reactivities, carbon nanotubes, graphene and fullerene were oxidized and modified with octadecylamine (ODA) in order to decrease van der Waals’s interaction and consequently improve the polymer-carbon nanostructures affinity for use in nanocomposites. Nanostructures were characterized as morphology, chemical structure, molecular conformation and thermal properties. All nanostructures showed results that confirm the modification with ODA, without geometry being altered. Modified nanostructures showed different percentages of ODA: graphene 86%, carbon nanotubes 83% and fullerene 63%. It was attributed to distinct reactivities, shapes and specific surface area available, due to different amounts of reactive terminals obtained before oxidation reactions. However, they showed a lower interfacial interaction, which is highly favorable for use in polymer nanocomposites.

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The present study obtained coated poly(lactic-co-glycolic acid) nanoparticles using the solvent displacement method aiming to evaluate the effect of the polymer concentration in the pharmaceutical formulations' and polymer properties. Nanosuspensions were evaluated by fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), zeta potential (ZP), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and time-domain nuclear magnetic resonance (TD-NMR). Uniform nanoparticles could be obtained using this method and higher polymer concentrations led to an increase in particle size and negatively charged surfaces were observed. However typical PLGA halo was observed in XRD, diffractograms revealed the Pluronic chains behavior when PLGA concentration changed. Additionally, samples' spin-lattice relaxation times, dipolar interaction and correlation times were evaluated using time-domain nuclear magnetic resonance (TD-NMR), which revealed the interference of PLGA chain packing when Pluronic was incorporated as well as Pluronic chains organization and its behavior around the particle.

More ecofriendly packaging can be obtained with the use of cellulose as a reinforcement and barrier. For this work, cellulose particles were incorporated in EVA matrix to obtain transparent EVA composite films with cellulose particles at different concentrations focusing on the improvement of the barrier properties. The films were obtained by solution casting. Commercial microcrystalline cellulose (MCC) was modified with glacial acetic acid, reducing the particle size. These modifications were monitored by FTIR, XRD, NMR and SEM. The composites formed by EVA/MCC were characterized by XRD, thermogravimetric analysis and mechanical properties to understand the influence of these particles on the displacement of the crystalline planes of the polymer matrix. The degree of crystallinity was also altered as larger concentrations of cellulose were added to EVA. TGA results showed no significant changes in the thermal degradation temperature of the material and, from DSC, it was seen that cellulose did not behave as a nucleating agent in EVA. The storage modulus obtained from the DMA analysis was inversely proportional to the cellulose content, indicating that there was an increase in the rigidity of the material caused by the dispersion of cellulose, which acts as a material reinforcement. These data were corroborated by the increase in the proton spin-lattice relaxation time values determined by NMR relaxometry technique, which provides information on sample molecular behavior, confirming the molecular interaction between material components.

In this study, poly(vinyl alcohol) (PVA)-based nanocomposites consisting of metallic oxide nanoparticles (TiO2, ZnO, ZrO2) were obtained from an aqueous solution of 7% PVA, in order to compare the microstructural, and physical properties of bionanocomposite films reinforced with various loading contents (0.1%, 0.2% and 0.3% w/w). They were evaluated regarding their molecular toughness through Nuclear Magnetic Resonance (NMR), regarding their chemical structural through Fourier Transform Infrared Spectroscopy (FTIR), regarding their crystallinity throught X-ray Diffraction (XRD), and regarding termal properties through Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The NMR results showed that the smallest concentrations of these oxides have a tendency to disperse better in the polymeric matrix, improving the structural toughness. Besides, changes in the termal resistance of the material were found with the use of TGA and DSC.

Scaffolds are three-dimensional biocompatible structures that can mimic the properties of the extracellular matrix (ECM) of a given tissue, like mechanical support and bioactivity, which provides a platform for cellular adherence, proliferation and differentiation. Consequently, scaffolds are frequently used in tissue engineering with the intention of assisting the regeneration of a damaged tissue, and a major application in bone regeneration. An ideal scaffold needs to be biodegradable, biocompatible, and needs to match the biomechanical properties of bone. Polymers are widely used in this field because they fulfil the first two requirements. However, no polymeric material can achieve mechanical properties similar to the bone. For that reason, polymeric nanocomposites, which consist of ceramic/metallic nanoparticles dispersed in a polymer matrix, are being considered for bone scaffold fabrication in order to overcome this problem, since nanoparticles are known to improve composite mechanical strength, and enhance other properties.

The loss of dentin adhesive efficiency can put at risk the durability of dental restorations. This loss of stability is a result of the combination of hydrolysis and the activity of metalloproteinases. The use of enzyme inhibitors can obtain higher adhesive stabilities. In this sense, the present paper aimed to evaluate the efficiency of doxycycline releasing adhesive systems using clay particles as a release modulator. The adhesive systems were based on BisGMA, UDMA, HEMA, and TEGDMA, including camphorquinone (photoinitiator) and ethanol (solvent). Different amounts of doxycycline (1–4%) were added to these systems in the presence or absence of 0.2% clay. The systems were evaluated by X-ray diffraction, infrared spectroscopy, flexural strength (and elastic modulus), doxycycline release, dentin MMP-2 inhibition capacity, and dentin adhesion. The results indicated that the addition of clays reinforces the adhesive systems mechanically, generating greater adhesive strengths. These nanoparticles also contribute to obtaining more controlled release profiles allowing a longer effective period of MMP-2 inhibition. The use of 1 and 2% of doxycycline, when combined with the clays, was able to elevate the adhesive stability after 18 months, indicating that clays in these systems represent a highly promising alternative to increasing the stability of dentin adhesion.

Objectives This study reports the evaluation of changes in crosslink structure and mechanical properties of dental microhybrid composite reinforced with clays when compared to silica nanofillers, which are already extensively used for this application. Materials and methods A standardized resin matrix with a glycerolate dimethacrylate, triethylene glycol dimethacrylate, and urethane dimethacrylate copolymers associated with a camphorquinone photoinitiator system was blended with 75 wt% filler content. As fillers, two organically modified clays (hydrophilic silica and organomodified silica) and a boron-aluminum-silicate glass with 4 µm were used to obtain nanohybrid nanocomposites. The samples were prepared by light curing and were evaluated by measuring flexural strength, elasticity modulus, hardness, tensile resistance, and crosslinking. Results The mechanical test results indicated that the system with 2.5% clay was better dispersed in the system, while the highest concentrations caused agglomeration of these clays. On the other hand, the silicas showed gradual gain in properties. The increase in concentration of all nanofillers reduced the crosslinking ability of the systems. This behavior can be explained because the clay’s presence makes the reaction medium more viscous or because the fillers act as points of light absorption and scattering.

The development of nanosystems in the pharmaceutical field has been growing in recent years. Polymers in particular are attractive since they can enable controlled release. Furthermore, surface modification is essential to increase nanosystem stability and prolong the blood circulation time. In this context, the present study obtained polycaprolactone (PCL) nanoparticles coated with poly(ethylene oxide)–poly(propylene oxide) triblock copolymer using the nanoprecipitation method, aiming to evaluate the effect of PCL concentration in this type of pharmaceutical formulation on prolongation of drug release. Nanosuspensions were evaluated by the following techniques: FT-IR, DLS, FESEM, TEM, ZP, TGA, DSC, XRD and TD-NMR. With higher PCL concentration, the particle size also increased and negative surface charge was observed. The nanoparticles' spherical shape was confirmed by FESEM and TEM while XRD and TD-NMR revealed changes in Pluronic chains' organization around the PCL matrix. Although this kind of polymer combination is already known in the pharmaceutical field, structural and molecular mobility evaluation with new perspectives were performed, mainly by XRD and TD-NMR.

Objective This study has investigated the influence of BisGMA, BisEMA, BisEMA 30, and two UDMA-based monomers (UDMA and Fit 852), with TEGDMA as co-monomer, on the degree of conversion, water sorption, water solubility, and optical properties of experimental dental composites. Methods Materials were formulated at 70/30 molar rations using BisGMA, BisEMA, BisEMA 30, UDMA or FIT 852, as base monomers, combined with TEGDMA. 60 wt% of silanated-glass particles was added. Degree of conversion (DC) and polymerization kinetics were monitored using Fourier-transformed infrared spectroscopy in the near-IR range. Water sorption (Wsp) and solubility (Wsl) were assessed using mass variation after 60 days water storage. Color was evaluated using a digital spectrophotometer, applying the CIELab parameters 24 h after dry storage and 60 days after water immersion to calculate ΔE values. All data were analyzed using ANOVA and Tukey’s test (pre-set alpha = 0.05). Results The BisGMA-based co-monomer mixture presented the lowest DC (62 ± 1%), whereas BisEMA 30 had the highest DC value (95 ± 2%). The highest Wsp was observed for BisEMA 30 (12.2 ± 0.8%), and the lowest for BisEMA (0.4 ± 0.1%). BisEMA has shown the lowest Wsl (0.03 ± 0.01%) and BisEMA 30 the highest one (0.97 ± 0.1%). The ΔE values showed that BisEMA 30 (7.3 color units) and Fit 852 (3.8 color units) altered the color stability providing ΔE > 3.3, which is considered clinically unacceptable. Conclusions The chemical composition and structure of the base monomer influenced the degree of conversion, water sorption, water solubility, and color stability. Considering the overall results, it is possible to state that the base monomer BisEMA mixed with the co-monomer TEGDMA presented the best performance in terms of all the parameters tested. Significance The resin matrix composition might influence physical property degradation processes and color stability of dental resin composites. Formulations based on BisEMA seem most promising for materials’ development.

The adhesive systems have the function to establish the connection between the restorative material and dental tissue, therefore it is of fundamental importance, because failures in the adhesive interface can reduce the life of a dental restoration. This study investigated the possibility of using the adhesive layer as a chlorhexidine modified release system evaluating their impact on the properties of these systems as well as evaluating the impact of these systems on immediate and post-aging dentin adhesion. Were used a matrix with BisGMA, UDMA, HEMA and TEGDMA copolymer and clay particles (Dellite 67G); associated with a chlorhexidine and a camphorquinone photoinitiator system. The properties of these systems were evaluated by the XRD, FTIR spectrophotometer, flexural strength, elasticity modulus, drug release, enzymatic inhibition and dentin adhesion resistance. The presence of the clay can raise the mechanical properties of the adhesive systems engendering a more resistant hybrid layer and led to a more sustained release of chlorhexidine in the systems, allowing a longer effective period of MMP-2 inhibition. The hypothesis that the addition of clays as release modulators could increase the effectiveness of these drugs in inhibiting the dentin's MPPs and consequently enhancing the adhesive durability was confirmed. These results indicate that the controlled release of chlorhexidine is able to reduce the process of loss of adhesion presenting itself as a promising system to increase the longevity of dental restorations.

Objectives To evaluate the effect of nanofiller loading on cure efficiency and potential color change of experimental composites. Materials and Methods Four different polymeric materials were produced using the same organic matrix blend. To this matrix, different amounts of 0.05 μm fumed silica filler were added: no filler, 13, 52, and 65wt%. Fourier transform infrared spectroscopy was used to evaluate the degree of conversion (DC) for each composite using near-IR analysis, and spectrophotometry according to CIELab chromatic space was used to evaluate the color change.To induce color change, composites were artificially aged with exposure to cycles of UV-B light for 300 hours. Trasmission electron microscopy was used to illustrate nanoffiler aglomeration in the resin matrix. Data were analyzed using correlation analysis (α = 0.05). Results There was an excellent inverse linear correlation between filler wt% and either DC or color change. Greater changes to red (+Δa) and yellow (+Δb) were observed as the filler wt% increased. Conclusions A higher percentage of nano-sized filler particles in dental resin composites directly affects their cure efficiency and potential for color change. Clinical Significance The increase in filler particle loading negatively affected monomer conversion and color stability of resin-based composites. As reduced filler loading results in poorer mechanical properties, to enhance color stability, resin-based composites should be formulated by making the refractive index of the polymeric matrix more closely match that of the filler throughout the polymerization process. (J Esthet Restor Dent, 2016)

The aim of this study was to obtaining an adhesive made of dimethacrylate copolymer and clay particles in different concentrations. The samples were prepared by light curing and were evaluated by XRD, FTIR and TGA as well as by measuring flexural strength, elasticity modulus and tensile resistance. The XRD and the mechanical test results indicated that the system with 0.2% clay is exfoliated, while the highest concentrations showed the agglomeration of these clays. FTIR was used to determine the conversion, and showed that use of clays particles are unable to significantly alter the polymerization until 1.0%. However, for the group containing 1.5%, there was a decline in this index. In the thermogravimetric analysis, only the groups with 0.2% of clays showed increased thermal resistance. In conclusion, the incorporation of clay at 0.2% concentration produces a well-dispersed system and can be applied as a dental adhesive.

In this work, multivariate empirical models using conventional near infrared (NIR) spectroscopy and hyperspectral images were employed, respectively, to determine and map the diethyleneglycol (DEG) content and the number of carboxylic end groups (TCG) in poly(ethylene terephthalate) fiber samples. NIR spectroscopy is a fast, clean and efficient technique. NIR spectral data were obtained using two conventional spectrometers and a hyperspectral camera. The regression models were built using partial least squares. The models showed satisfactory results for the evaluated parameters, with Root Mean Squared Error of Prediction (RMSEP) values equivalent to repeatability of the reference methods. The distribution maps of the DEG and TCG content in the fibers samples were obtained by using the models built with the average spectra of the images to estimate the pixel content of each species, allowing us to identify areas with high content of these parameters.

Due to the high incidence of bone fractures in the population, it became necessary to produce scaffolds that are able to assist in tissue regeneration. It is necessary to find an appropriate balance between the mechanical and biological properties, in order to mimic the natural tissue, these properties are directly related to the architecture and their degree of porosity, as well as the size of their pores and their interconnectivity. In this perspective, the 3D printing stands out, where the structure is obtained layer by layer, according to a predetermined computational model which provides a greater control of architecture and scaffold geometry and overcomes, in this way, the limitations of traditional techniques of scaffolds manufacturing. In this way, the objective of this seminar is to present the state of the art of the polymer scaffolds produced by 3D printing and applied to bone tissue regeneration, highlighting the advantages and limitations of this process.

Spin-lattice and spin-spin relaxation times are one of the most attractive tools in the solid-state nuclear magnetic resonance spectroscopy to evaluate the level of clay dispersion in the nanocomposite matrices. The efficiency of the relaxation processes can be used to evaluate the nanoparticles intermolecular interactions and, consequently, the dispersion of them in the polymer matrix, the molecular dynamic of the hybrid compounds, as well as the molecular domains formation in an organic material. The determination of relaxation parameters was carried out to evaluate the organoclay exfoliation and intercalation process in the polymeric matrix, in addition to their dispersion and distribution in the matrix. The proton NMR relaxation data showed that the polymeric nanomaterials investigated presented good intermolecular interaction that promoted good nanoparticles dispersion and distribution in the hybrid materials. The proportion of 2% clay promoted a greater heterogeneity in the matrix compared to other ratios; 1% clay influenced only to the higher molecular rigidity phase; and 3% clay had a decrease in heterogeneity compared to 2% though still influenced the matrix as a whole. These results prove the efficiency of NMR technique in the evaluation of nanofillers interaction with polymer matrices, as well as their dispersion and distribution.

Purpose To evaluate the degree of conversion, absorption, and solubility in water of self-adhesive resin cements subjected to different time intervals between material preparation and the photoactivation procedure. Materials and Methods Two dual self-adhesive resin cements were tested: RelyX Unicem and SmartCem2. The degree of conversion as a function of time was evaluated by Fourier-transformed infrared spectroscopy using the attenuated total reflectance technique. Three time intervals between handling and photoactivation were applied: Group 1 = immediately; Group 2 = a 1-minute interval; Group 3 = a 4-minute interval. All specimens were irradiated with a light-emitting diode source for 40 seconds. Thirty discs of each cement (1 mm thick × 6 mm diameter, n = 10) were prepared for the absorption and solubility tests. These specimens were stored in distilled water at 37°C for 90 days. The results were subjected to ANOVA with two factors (material and activation time intervals) and Tukey's test (95% significance). Results The 4-minute interval significantly reduced the degree of conversion of SmartCem2 (30.6% ± 8.3%). No other significant changes were observed for the degree of conversion; however, the time intervals before photoactivation interfered significantly in the water absorption of the RelyX Unicem specimens but not the SmartCem2 specimens. The time intervals did not affect the solubility of either cement. In all cases, SmartCem2 had higher solubility than RelyX Unicem. Conclusion The time interval between handling and photoactivation significantly influenced the degree of conversion and water sorption of the resin-based cements. In general, one can say that the self-adhesive resin cements should be photoactivated as soon as possible after the material handling process.

The antibiotic cotrimoxazole was associated with poly(lactic acid-co-glycolic acid) (PLGA) and maghemite, aiming to reach a controlled drug release system. PLGA was synthesized through the polycondensation of lactic acid and glycolic acid in an equimolar ratio, and maghemite was synthesized through the coprecipitation method. The drug cotrimoxazole was inserted in the composite through three different procedures: solution, fusion, and in situ to check the best insertion method. Several techniques were used to characterize the materials. The copolymer was characterized by nuclear magnetic resonance and size-exclusion chromatography. In addition, the maghemite, the composites containing the drug, and the polymer were characterized by Fourier transform infrared spectroscopy (FTIR) with attenuated total reflectance device, small-angle X-ray scattering, and magnetic force, this last according to the methodology developed by our group. The root mean square error was used to compare the FTIR spectra of the samples, proving that the fusion method was the best way to insert the drug and maghemite in the polymer. Therefore, composites containing the drug and the nanoparticles were prepared by the fusion method. These composites were used for dissolution profile studies, which were monitored with and without magnetic field, aiming to understand the influence of the magnetic field on the dissolution profile. The dissolution was monitored and quantified using the ultraviolet-visible spectrophotometry, following the United States Pharmacopeia (USP) method for cotrimoxazole tablets. Results demonstrated that nanocomposites presented a good magnetic force, able to keep the magnetic composite trapped in a specific place or tissue. The presence of the nanoparticles in the composites changed the kinetics of the drug release, as they constitute physical barriers to the drug diffusion, contributing to a sustained drug release process. Furthermore, in the presence of a magnetic field, the magnetic nanoparticles were able to perform a magnetic constriction of the material, making the drug release faster than in the absence of the magnetic field, which may be useful to perform a fine tuning of the system, allowing the easier adjustment of the speed and amount of released drug, useful to improve medical treatments and even the welfare of the patients. POLYM. ENG. SCI., 53:2308–2317, 2013. © 2013 Society of Plastics Engineers