Drug-loaded mesoporous silica on carboxymethyl cellulose hydrogel: Development of innovative 3D printed hydrophilic films.

3D printing has been explored as an emerging technology for the development of versatile and printable materials for drug delivery. However, the alliance of 3D printing and nanomaterials has, to date, been little explored in pharmaceutics. Herein, a mesoporous silica with nanostructured pores, SBA-15, was used as a drug carrier for triamcinolone acetonide, a hydrophobic drug, with the aim of incorporating the drug formulation in a hydrophilic printable ink. The adsorption of the drug in the SBA-15 pores was confirmed by the decrease in its surface area and pore volume, along with an increase in the apparent aqueous solubility of triamcinolone acetonide, as shown by in vitro release studies. Thereafter, a hydrophilic ink composed of carboxymethyl cellulose containing drug-loaded SBA-15 was formulated and 3D printed as hydrophilic polymeric film using the semisolid extrusion technique (SSE). The 3D printed films showed complete drug release after 12 h, and the presence of the triamcinolone acetonide-loaded SBA-15 improved their in vitro mucoadhesion, suggesting their promising application in oral mucosa treatments. Besides representing an innovative platform to develop water-based mucoadhesive formulations containing a hydrophobic drug, this is the first report proposing the development of SSE 3D printed nanomedicines containing drug-loaded mesoporous silica.

Bioadhesive 3D-Printed Skin Drug Delivery Polymeric Films: From the Drug Loading in Mesoporous Silica to the Manufacturing Process.

The alliance between 3D printing and nanomaterials brings versatile properties to pharmaceuticals, but few studies have explored this approach in the development of skin delivery formulations. In this study, clobetasol propionate (CP) was loaded (about 25% w/w) in mesoporous silica nanomaterial (MSN) to formulate novel bioadhesive and hydrophilic skin delivery films composed of pectin (5% w/v) and carboxymethylcellulose (5% w/v) by 3D printing. As a hydrophobic model drug, CP was encapsulated in MSN at a 3:1 (w/w) ratio, resulting in a decrease of CP crystallinity and an increase of its dissolution efficiency after 72 h (65.70 ± 6.52%) as compared to CP dispersion (40.79 ± 4.75%), explained by its partial change to an amorphous form. The CP-loaded MSN was incorporated in an innovative hydrophilic 3D-printable ink composed of carboxymethylcellulose and pectin (1:1, w/w), which showed high tensile strength (3.613 ± 0.38 N, a homogenous drug dose (0.48 ± 0.032 mg/g per film) and complete CP release after 10 h. Moreover, the presence of pectin in the ink increased the skin adhesion of the films (work of adhesion of 782 ± 105 mN·mm). Therefore, the alliance between MSN and the novel printable ink composed of carboxymethylcellulose and pectin represents a new platform for the production of 3D-printed bioadhesive films, opening a new era in the development of skin delivery systems.

Recycled low-density polyethylene composite to mitigate the environmental impacts generated from coal mining waste in Brazil.

Waste materials from coal mining and consumer products can pose significant risks to the environment. Residual coal deposits lead to the formation of acid drainage and release of contaminants, causing negative changes in soil and aquatic systems. Low density polyethylene (LDPE) polymers are an environmental concern due to their high useage, and slow degradation in the environment. In this study both waste materials were used to develop a composite to mitigate the environmental impacts of coal mining waste (CMW). The composite material was produced in different formulations (0-80 % wt CMW), and samples were tested for formation of acid drainage and release of contaminants. Chemical characterisation of the CMW and leachate of the composite materials was performed by X-ray fluorescence and atomic absorption spectrometry. Ecotoxicological effects in soil and water were investigated using standard tests with the earthworm, Eisenia fetida, the collembolan, Folsomia candida and the bacterium, Aliivibrio fischeri. Composites with 20 % wt LDPE showed a 50% increase in the pH value of the leachate compared to the CMW leachate. Iron, aluminium and sulfate concentrations were lower in leachates of the composite materials, and a reduction in the ecotoxicological impact on the tested organisms was observed. The hydrophobic nature of the composite's polymeric matrix as well its physical properties contributed to a better coating of the coal residue particles, blocking the contact with water and reducing the environmental risks of CMW. These results show that the production of composite material is a viable alternative route for treating coal and LDPE waste.

Long-term bonding efficacy of adhesives containing benzodioxioles as alternative co-initiators.

This study evaluated the three-year lifespan of the bond to dentin of experimental self-etch adhesives containing benzodioxole derivatives - 1,3-benzodioxole (BDO) and piperonyl alcohol (PA) - as co-initiator alternative to amines. Adhesive resins were formulated using Bis-GMA, TEGDMA, HEMA, camphorquinone and different co-initiators: BDO, PA or ethyl 4-dimethylamino benzoate (EDAB - amine). An experimental self-etch primer was used to complete the two-step, self-etch adhesive system. Clearfil SE Bond (CSE) was used as commercial reference. Bond strength to human dentin was assessed by microtensile bond strength (µTBS) test, and failure mode was classified. Morphology of the dentin bonding interface was assessed via scanning electron microscopy (SEM). Irrespective of the dental adhesives evaluated, µTBS was higher after 24 hours compared with that after 1.5 and 3 years (p ≤ 0.001). However, adhesives with BDO and PA as co-initiators showed significantly higher bond strength than the bonding resin with EDAB (p ≤ 0.002), independent of the time evaluated. The commercial adhesive CSE showed similar bond strength compared with the other groups (p ≥ 0.05). Mixed failures were mainly observed after 24 hours, while adhesive failures were more frequently observed after 1.5 and 3 years. No notable differences in homogeneity and continuity along the bonded interfaces were detected among the materials in the SEM analysis. In conclusion, benzodioxole derivatives are feasible alternative co-initiators to tertiary amine in camphorquinone-based self-etching dental adhesive formulations.

Acrylamides and methacrylamides as alternative monomers for dental adhesives.

OBJECTIVE: Synthesize and characterize a methacrylamide monomer for adhesive system and evaluate the physicochemical properties of the adhesive resin. METHODS: The liquid methacrylamide monomer N,N',N″-(nitrilotris(ethane-2,1-dyil)tris(2-methylacrylamide) (TMA) was prepared by reaction of methacrylic anhydride and tris(2-aminoethyl)amine with 60% yields. The TMA structure was analyzed by 1H NMR, 13C NMR, ATR-FTIR and UHPLC-QTOF-MS. Experimental adhesive resin containing bisphenol-A glycidyl methacrylate (BISGMA), 2-hydroxyethylacrylamide (HEAA), 2-hydroxyethylmethacrylate (HEMA) and TMA were formulated. Polymerization kinetics of neat TMA and experimental adhesive resin (TMA33%/HEAA66%, TMA50%/HEAA50%, TMA66%/HEAA33%, TMA50%/HEMA50%, BisGMA/HEAA/TMA and BisGMA/HEMA) were evaluated using Differential Scanning Calorimetry. Physiochemical properties for BisGMA/HEAA/TMA and BisGMA/HEMA adhesives were evaluated by cytotoxicity, ultimate tensile strength (UTS), softening in solvent (ΔKHN), contact angle (θ), microtensile bond strength (µTBS) and failure analysis. A primer was also formulated with H2O/HEAA/AMPS (2-acrylamido-2-methylpropane sulfonic acid) and the pH value was verified and compared to commercial primer. RESULTS: Adhesive resin with only HEAA and TMA (TMA33%/HEAA66%, TMA50%/HEAA50%, TMA66%/HEAA33%) showed lower conversion and polymerization rate after 40s of light activation. Conversion up to 60% was found for BisGMA/HEAA/TMA and BisGMA/HEMA adhesive resin without significant difference between groups, p>0.05. Cytotoxicity, UTS, µTBS, ΔKHN and θ showed no statistical difference, p>0.05, between BisGMA/HEAA/TMA and BisGMA/HEMA adhesive resin. SIGNIFICANCE: In this study, the proposed synthetic route resulted in a tris(methacrylamide). A new primer composed without acrylates or methacrylates was formulated for 3-step etch-and-rinse adhesive system without the presence of HEMA monomer. Physicochemical properties and cell viability of BisGMA/HEAA/TMA adhesive resin represents an alternative adhesive resin without HEMA monomer.

Piperonyl methacrylate: Copolymerizable coinitiator for adhesive compositions.

OBJECTIVES: This study describes the synthesis of piperonyl methacrylate (PipM) and evaluates its effect when used as coinitiator in the photoinitiated radical polymerization of experimental adhesive resins. METHODS: PipM was synthetized through an esterification reaction and characterized by FTIR and 1H NMR spectroscopy. Adhesive resins containing camphorquinone as photoinitiator and PipM or ethyl-4-dimethyl amine benzoate (EDAB) as coinitiators were formulated. Scotchbond Multipurpose (SBMP) adhesive was used as commercial reference. All materials were analyzed for polymerization kinetics, flexural strength, elastic modulus, water sorption/solubility, shear bond strength to bovine enamel and dentin, characterization of hybrid layer by scanning electron microscopy (SEM), microbiological direct contact test, and cytotoxicity. RESULTS: The adhesive with PipM presented higher degree of conversion and lower sorption/solubility when compared with other groups. Shear bond strength to enamel and dentin were similar for PipM and EDAB materials. The percentage of cellular viability was close to 100% and similar in the experimental groups and the commercial reference. CONCLUSIONS: PipM presented similar or superior performance to the tertiary amine used as control, representing a potential alternative coinitiator for photopolymerizable dental materials. CLINICAL SIGNIFICANCE: PipM could be potentially useful in the formulations of adhesive systems with enhanced chemical properties, which could mean improvement in the longevity of composite resin restorations.

Long-term bonding efficacy of adhesives containing benzodioxioles as alternative co-initiators

Abstract This study evaluated the three-year lifespan of the bond to dentin of experimental self-etch adhesives containing benzodioxole derivatives - 1,3-benzodioxole (BDO) and piperonyl alcohol (PA) - as co-initiator alternative to amines. Adhesive resins were formulated using Bis-GMA, TEGDMA, HEMA, camphorquinone and different co-initiators: BDO, PA or ethyl 4-dimethylamino benzoate (EDAB - amine). An experimental self-etch primer was used to complete the two-step, self-etch adhesive system. Clearfil SE Bond (CSE) was used as commercial reference. Bond strength to human dentin was assessed by microtensile bond strength (µTBS) test, and failure mode was classified. Morphology of the dentin bonding interface was assessed via scanning electron microscopy (SEM). Irrespective of the dental adhesives evaluated, µTBS was higher after 24 hours compared with that after 1.5 and 3 years (p ≤ 0.001). However, adhesives with BDO and PA as co-initiators showed significantly higher bond strength than the bonding resin with EDAB (p ≤ 0.002), independent of the time evaluated. The commercial adhesive CSE showed similar bond strength compared with the other groups (p ≥ 0.05). Mixed failures were mainly observed after 24 hours, while adhesive failures were more frequently observed after 1.5 and 3 years. No notable differences in homogeneity and continuity along the bonded interfaces were detected among the materials in the SEM analysis. In conclusion, benzodioxole derivatives are feasible alternative co-initiators to tertiary amine in camphorquinone-based self-etching dental adhesive formulations.

Influence of dye and nylon fibers on microwave-cured acrylic resin properties / Influência de corante e fibras de nylon nas propriedades de uma resina acrílica polimerizada por micro-ondas

ABSTRACT Objective: The aim of this study is to analyze if both color and nylon fibers have an influence on microwave-cured acrylic resin properties. Methods: Rectangular and disk-shaped specimens were prepared using acrylic resins; medium pink with and without nylon fibers and colorless without nylon fibers. To obtain the rectangular specimens, a stainless steel die was used with the following dimensions: 64 X 10 x 3 mm (± 0.5mm). To obtain disk-shaped specimens, a die 50mm (±0.5mm) in diameter and 0.5mm (±0.05mm) thick was employed. They were randomized to form groups: control (colorless acrylic) and experimental (medium pink, with and without nylon fibers), with each group consisting of ten (10) specimens rectangular in shape and five (5) disk-shaped. They were analyzed in six (6) assays (izod impact strength, n=10; Knoop hardness, n=10; glass transition temperature, n=3; water sorption and solubility, n=5; degree of monomer/polymer conversion, n=1; flexural strength and flexural modulus, n=10). All variables were subjected to the analysis of variance test followed by Tukey's multiple comparison test, at a 5% level of significance. Results: The analysis of the monomer/polymer degree of conversion did not reveal any difference between the three groups of resins (medium pink, with and without nylon fibers and colorless resin); it was approximately 88%. The results did not show significant differences between the groups for each variable (p>0.05). Conclusion: The results showed that color and presence of nylon fibers in acrylic resins did not affect the properties analyzed in this study.

RESUMO Objetivo: Analisar se corantes e fibras de nylon influenciam nas propriedades de uma resina acrílica ativada por energia de micro-ondas. Métodos: Espécimes retangulares e em forma de disco foram confeccionados em resina acrílica rosa médio com e sem fibras de nylon e incolor sem fibras. Para obter os espécimes retangulares, foi utilizada uma matriz de aço inoxidável com as seguintes dimensões: 64 X 10 X 3 (± 0,5mm) e para obter os espécimes em forma de disco, foi utilizada uma matriz com 50mm (± 0,5mm) de diâmetro e 0,5mm (±0,05mm) de espessura. Os mesmos foram randomizados para formar os grupos controle (acrílico incolor sem fibras) e experimentais (rosa médio com e sem fibras), sendo cada grupo composto por dez (10) espécimes retangulares e cinco (5) em forma de disco. Foram os mesmos então submetidos a seis (6) ensaios (resistência ao impacto izod, n=10; dureza knoop, n=10; temperatura de transição vítrea, n=3; sorção e solubilidade, n=5; grau de conversão, n=1; resistência à flexão e módulo de flexão, n=10). Todas as variáveis foram submetidas à análise de variância seguida pelo teste de comparações múltiplas de Tukey, com nível de significância de 5%. Resultados: O grau de conversão foi de 88% para os 3 grupos de resinas e os resultados não mostraram diferença estatisticamente significativa entre os mesmos para cada variável (p>0,05). Conclusão: Os resultados mostraram que o corante e a presença de fibras de nylon em resina acrílica não afetaram as propriedades analisadas nesse estudo.

Influence of hydroxyethyl acrylamide addition to dental adhesive resin.

OBJECTIVE: to determine the physicochemical properties of experimental adhesive resins containing hydroxyethyl acrylamide. METHODS: Three groups of experimental resin were formulated, GHEAA33% (33.3wt% HEAA+66.6wt% BisGMA), GHEAA50% (50wt% HEAA+50wt% BisGMA), and GHEAA-FREE (33.3wt% HEMA+66.6wt% of BisGMA). The polymerization process of each adhesive resin group, as well as for the homopolymers, BisGMA, HEMA, HEAA, HEMA* without EDAB, and HEAA* without EDAB, was characterized through differential scanning calorimetry (DSC). Elution of monomers was evaluated by (1)H NMR. Dynamic mechanical analysis (DMA) was used to collect the glass transition temperature (Tg), the storage modulus (E') and the reticulation degree (ρ). Flexural strength was calculated by three-point bending test with 0.75mm/min. Softening in solvent was calculated through hardness before and after immersion in water or ethanol. RESULTS: GHEAA50%, GHEAA33%, GHEAA-FREE presented higher polymerization rate ( [Formula: see text] , 12.3 and 5.3mmolg(-1)s(-1), respectively) than homopolymers HEMA, HEMA* and HEAA*. Group with HEAA presented higher degree of conversion (GHEAA50%=64.07%>GHEAA33%=55.82%>GHEAA-FREE=49.02%; p=0.008) All groups presented low elution of monomers (p>0.05). The values of E' were higher on GHEAA33% than GHEAA-FREE (p=0.034). Tg and flexural strength values of GHEAA-FREE were higher than acrylamide groups (p=0.022 and p<0.001, respectively). Hardness varied from 27.05 to 34.78 for water and from 63.27 to 68.51 for ethanol with no difference for ρ values. SIGNIFICANCE: The addition of HEAA increased the materials reactivity and, consequently, improved the maximum rate of polymerization, degree of conversion and the storage modulus of experimental adhesive resin.

Acrylic resin disinfection by peracetic acid and microwave energy / Avaliação da efetividade do ácido peracético e da irradiação por microondas na desinfecção de resina acrílica

Objective: The objective of this study was to evaluate the effectiveness of disinfection methods in microwave and immersion in peracetic acid in heat-cured, self-cured and microwave-cured acrylic resin, contaminated with Candida albicans.Methods: Five specimens were prepared for each type of acrylic resin. All were infected with Candida Albicans, incubated at 37°C for 24 hours. The group which underwent microwave energy was irradiated with a power of 840W for 1 minute and the other group underwent disinfection by soaking of 0.2% peracetic acid for 5 minutes.Results: All samples proved to be contaminated after the incubation period. After the different processes of disinfection, both immersion in 0.2% peracetic acid as microwave irradiation were effective in disinfection of the 3 types of acrylic resins contaminated by Candida Albicans.Conclusion: Concluded that soaking in 0,2% peracetic acid for 5 minutes with microwave irradiation power 840W for 1 minute are effective methods for disinfecting heat-cured acrylic resin, self-cured acrylic resin and microwave-cured acrylic resin, contaminated with Candida Albicans.

Objetivo: Avaliar a eficácia dos métodos de desinfecção em microondas e imersão em ácido peracético em resina acrílica termopolimerizável, autopolimerizável e resina acrílica polimerizada por microondas, contaminadas com Candida albicans.Métodos: Cinco amostras foram preparadas para cada tipo de resina acrílica. Todas foram infectadas com Candida Albicans, incubadas a 37 ° C durante 24 h. O grupo submetido a energia de microondas foi irradiada com uma potência de 840W durante 1 minuto e o outro grupo foi submetido a desinfecção por imersão de ácido peracético a 0,2% durante 5 minutos.Resultados: Todas as amostras mostraram estar contaminadas depois do período de incubação. Depois dos diferentes processos de desinfecção, tanto a imersão em 0,2% de ácido peracético, como a irradiação de microondas foram eficazes na desinfecção dos 3 tipos de resinas acrílicas contaminados por Candida Albicans.Conclusão: Concluiu-se que a imersão em ácido peracético 0,2% durante 5 minutos e a irradiação de microondas com potência de 840W durante 1 minuto são métodos eficazes para a desinfecção de resina acrílica termopolimerizável, resina acrílica autopolimerizável e resina acrílica polimerizada por microondas, contaminados com Candida Albicans.

Polymer-coated palladium nanoparticle catalysts for Suzuki coupling reactions.

A set of seven different palladium nanoparticle (PdNP) systems stabilized by small amounts (1.0mg/mL) of structurally related macromolecular capping agents were comparatively tested as catalyst in p-nitrophenol (Nip) reduction and Suzuki cross-coupling reactions. The observed rate constants (kobs) for Nip reduction were in the range of 0.052-3.120×10(-2)s(-1), and the variation reflected the effects of polymer chain conformation, ionic strength and palladium-polymer complex coordination. Macromolecules featuring pendant pyridyl moieties or inverse temperature-dependent solubility were found to be unsuitable capping agents for PdNPs catalysts, despite being active. The catalytic activity in Suzuki cross-coupling reactions followed the same behavior; the most active particles in the Nip reaction also mediated the cross-coupling reaction providing the expected products in quantitative yields under relatively mild conditions after only 4h at 50°C. Experiments involving the successive addition of reactants and catalyst recovery/re-use indicated that the recycling potential was comparable to those of the standards used in this field.

Electrospray induced surface activation of polystyrene microbeads for diagnostic applications.

Electrospray is generally regarded as a "soft" technique due to the absence of any observable molecular fragmentation or destruction. This study reports on a novel and easy way to induce surface activation on the surface of polystyrene microbeads through electrospray deposition into a grounded aqueous electrolyte solution bath. This process, nicknamed EISA, which stands for electrospray induced surface activation, proposes that when a highly charged microbead formed by the electrospray process sinks into the aqueous electrolyte solution, it behaves like a highly charged spherical capacitor that discharges in the conductive liquid. The energy released leads to a breakup of the polystyrene surface bonds and water oxidation with oxygen. Further reactions produce a carboxylated surface that was confirmed by X-ray photoelectron spectroscopy (XPS) and protein coupling. An immunoassay based on these modified microbeads was also developed and presented for use in syphilis detection, demonstrating a reliable signal-to-noise ratio between positive and negative results.

Synthesis of tacrine-lophine hybrids via one-pot four component reaction and biological evaluation as acetyl- and butyrylcholinesterase inhibitors.

A novel series of tacrine-lophine hybrids was synthesized and tested for their ability to inhibit acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) with IC50 in the nanomolar concentration scale. The key step is the one-pot four component condensation reaction of 9-aminoalkylamino-1,2,3,4-tetrahydroacridines, benzil, different substituted aromatic aldehydes and NH4OAc, using InCl3 as the best catalyst. Tacrine-lophine hybrids were found to be potent and selective inhibitors of cholinesterases. As an extension of the four component approach to tetrasubstituted imidazoles, a new series of bis-(2,4,5-triphenyl-1H-imidazoles) or bis(n)-lophines was tested against AChE and BuChE.

Niobium pentoxide as a novel filler for dental adhesive resin.

OBJECTIVES: The purpose of this study was to develop an adhesive resin with incorporation of niobium pentoxide and evaluate its properties. METHODS: Niobium pentoxide was characterised by X-ray diffraction, surface area, particle size, micro-Raman, scanning electron microscopy and the effectiveness of silanisation process by Fourier Transform Infrared (FTIR). An experimental adhesive resin was formulated with 0, 5, 10 and 20wt% Nb(2)O(5). The formulated adhesive resins were evaluated based on microhardness, degree of conversion, radiopacity and interface (resin/dentine) characterisation by micro-Raman. RESULTS: The particles used in this study presented a monoclinic crystalline phase with typical chemical groups and micrometre mean size. Microhardness and radiopacity increased with higher amounts of Nb(2)O(5), and the particles were able to penetrate into the hybrid layers. CONCLUSIONS: Therefore, Nb(2)O(5) may be an alternative for polymer-based biomaterials. CLINICAL SIGNIFICANCE: Niobium pentoxide could be used to produce adhesive resins with enhanced properties.

Influence of 2-hydroxyethyl methacrylate concentration on polymer network of adhesive resin.

PURPOSE: To evaluate the effect of variations in 2-hydroxyethyl methacrylate (HEMA) concentrations in an experimental comonomer blend on degree of conversion, water sorption, solubility, and ultimate tensile strength of adhesive resin. MATERIALS AND METHODS: The effect of HEMA content (0, 15, 30, and 50%wt - control, G15, G30, and G50 groups, respectively) was tested in an experimental comonomer blend of bis-GMA, bis-EMA, TEG-DMA, and HEMA. The degree of conversion, polymerization rate, ultimate tensile strength, water sorption, and solubility of the adhesive resin blends were determined. RESULTS: At 40 s of light activation time, groups G30 and G50 showed a decrease of 30% and 61%, respectively, in degree of conversion compared to control. Water sorption and solubility differed for all groups, and was statistically higher in G50. For ultimate tensile strength, the control and G15 groups showed statistically higher values than the other groups (p < 0.05). CONCLUSION: Higher HEMA content increases dental adhesive resin degradation.

Inhibition of the activity of matrix metalloproteinase 2 by triethylene glycol dimethacrylate.

The aim of this study was to evaluate the effect of different concentrations of triethylene glycol dimethacrylate (TEGDMA) on the inhibition of matrix metalloproteinase 2 (MMP-2). Mouse gingival explants were cultured overnight in DMEM and the expression of secreted enzymes was analyzed by gelatin zymography in buffers containing 5 mM CaCl(2) (Tris-CaCl(2)) in 50 mM Tris-HCl buffer with the addition of TEGDMA at different concentrations (0.62%, 1.25%, 2.5%, or 5.0% (v/v)). The gelatinolytic proteinase present in the conditioned media was characterized as matrix metalloproteinase by means of specific chemical inhibition. The matrix metalloproteinases present in the conditioned media were characterized as MMP-2 by immunoprecipitation. The eletrophoretic bands were scanned and the transmittance values were analyzed. Data was plotted and submitted to linear regression to investigate MMP-2 inhibition as a function of TEGDMA concentration. Three major bands were detected in the zymographic assays. These bands were characterized as MMP-2. Zymogene (72 kDa), intermediate (66 kDa) and active forms of MMP-2 (62 kDa) were inhibited by TEGDMA in a dose-dependent way. These findings suggest that TEGDMA could inhibit MMP-2 expression even at small concentrations.

Synthesis and AChE inhibitory activity of new chiral tetrahydroacridine analogues from terpenic cyclanones.

This work describes the enantioselective synthesis of a new series of terpenic chiral 9-aminotetrahydroacridine analogues. Several chiral ketones were synthesized from natural monoterpenes in an optically active form and subjected to the cyclodehydration reactions with anthranilonitrile in the presence of BF(3).Et(2)O as catalyst. The 9-aminotetrahydroacridine analogues were tested as acetylcholinesterase (AChE) inhibitors. Based on qualitative structure-activity relationship some trends are suggested.

Endoscopic augmentation of the esophagogastric junction with polymethylmethacrylate: durability, safety, and efficacy after 6 months in mini-pigs.

BACKGROUND AND AIMS: Endoscopic augmentation of the esophagogastric junction (EGJ) with polymethylmethacrylate (PMMA) has been reported in an experimental short-term study. We assessed whether endoscopic augmentation of the EGJ with PMMA is durable, safe, and efficacious after 6 months in mini-pigs. METHODS: Ten mini-pigs were studied under anesthesia. After a pilot study in two animals, eight mini-pigs underwent lower esophageal sphincter (LES) manometry and gastrostomy with measurement of gastric yield volume (GYV) and gastric yield pressure (GYP). Endoscopic implantation of PMMA was performed aiming for the submucosa of the EGJ. Six months later, LES manometry and GYV and GYP measurements were repeated and animals were sacrificed, followed by microscopic analyses of the EGJ. RESULTS: Out of 32 implants (four per animal), 29 (91%) were identified as submucosal nodules postmortem. PMMA deposits were found at microscopic analysis in all animals and located as follows [mean (range)]: submucosa 61.5% (37.5-91%), muscularis propria 21.5% (0-58%), mucosa 11% (0-25%), and subserosa 6% (0-17%). Neither esophageal perforation nor death was observed. A significant increase in GYV (1,404 versus 905 ml; p = 0.02) and a borderline increase in GYP (8.1 versus 6.5 mmHg; p = 0.057) were detected 6 months later. CONCLUSIONS: Endoscopic augmentation of the esophagogastric junction with PMMA was durable and had no complications after 6 months. However, the occurrence of implants in the subserosa requires technical refinement before use in clinical trials.

Influence of water concentration in an experimental self-etching primer on the bond strength to dentin.

PURPOSE: To investigate the influence of different water concentrations in the solvents of self-etching primers on microtensile bond strength (LTBS) of an experimental adhesive system. MATERIALS AND METHODS: Five experimental self-etching primers with 0, 5, 10, 20 and 40 (wt%) water as solvent were formulated. An experimental adhesive resin (AD-50) was also synthesized to create one experimental self-etching adhesive system. Clearfil SE Bond (CSEB) was used as the commercial reference. Sixty bovine incisors were randomly separated into 6 groups. Buccal enamel was removed to expose the superficial coronal dentin; this surface was polished wet to create a standardized smear layer. After rinsing, water was removed, leaving the surface visibly dried. The dentin surfaces were etched with primer and air dried, adhesive resin was applied and photoactivated, then the composite resin restoration was placed. After storage for 24 h, the specimens were sectioned with a cooled diamond saw at low speed. Microtensile bond strength was measured and data were analyzed with one-way ANOVA/Tukey's test (alpha = 0.05). RESULTS: ANOVA showed that primer composition was a significant factor for bond strength. There was no significant difference in bond strengths between the primers with a water concentration of 40% (53.9 +/- 12.7 MPa), 20% (51.1 +/- 11.5 MPa, and 10% (47.5 +/- 11.4 MPa), and CSEB (50.7 +/- 9.8 MPa). The groups with 5% (38.6 +/- 12.9 MPa) and 0% (31.5 +/- 7.5 MPa) water presented similar bond strengths amongst themselves but were statistically significantly lower than that of the other groups. CONCLUSION: The water concentration in the primer solvent exercises a significant influence on the bond strength of this experimental self-etching adhesive system.

Synthesis of phosphate monomers and bonding to dentin: esterification methods and use of phosphorus pentoxide.

OBJECTIVES: The aim of this study was to synthesize an acidic monomer using an alternative synthetic pathway and to evaluate the influence of the acidic monomer concentration on the microtensile bond strength to dentin. METHODS: The intermediary 5-hydroxypentyl methacrylate (HPMA) was synthesized through methacrylic acid esterification with 1,5-pentanediol, catalyzed by p-toluenesulfonic acid. To displace the reaction balance, the water generated by esterification was removed by three different methods: anhydrous sodium sulfate; molecular sieves or azeotropic distillation. In the next step, a phosphorus pentoxide (4.82 mmol) slurry was formed in cold acetone and 29 mmol of HPMA was slowly added by funnel addition. After the reaction ended, solvent was evaporated and the product was characterized by 1HNMR and FTIR. The phosphate monomer was introduced in a self-etch primer at concentrations of 0, 15, 30, 50, 70 and 100 wt%. Clearfil SE Bond was used as commercial reference. Microtensile bond strength to dentin was evaluated 24h after the bonding procedures, followed by fracture analysis (n=20). Data was submitted to ANOVA and Tukey's post hoc test. RESULTS: The highest yield was obtained (62%) when azeotropic distillation was used, while the reaction with molecular sieves was not feasible. The phosphoric moiety attachment to the monomer was successfully performed with a quantitative yield that reached around 100%. The acidic monomer concentration significantly affected the bond strength and the highest mean (55.1+/-12.8 MPa) was obtained when 50% of acidic monomer was used. CONCLUSION: The synthesis pathways described in the present study appear to be a viable alternative for developing phosphate monomers.