Effect of SiO2 and Al2 O3 nanoparticles on wear resistance of PMMA acrylic denture teeth / Efeito das nanopartículas de SiO2 e Al2 O3 na resistência ao desgaste de dentes em acrílico PMMA para prótese

Objetivo: Este estudo teve como objetivo avaliar a resistência ao desgaste de dentes em acrílico para próteses contendo nanopartículas de dióxido de silício (nano-SiO2 ) e dióxido de alumínio (nanoAl2 O3 ). Material e Métodos: O material em polimetilmetacrilato (PMMA) foi utilizado para fabricar 84 amostras (n=10) contendo nano-SiO2 e nano-Al2 O3 nas concentrações 0,1% em peso, 0,3% em peso e 0,5% em peso de pó acrílico. Uma máquina de teste de desgaste de dois corpos e um microscópio digital foram usados para medir as mudanças na perda de peso e rugosidade da superfície, respectivamente. Testes de ANOVA a um fator e testes de comparações múltiplas de Tukey foram utilizados para análise dos dados (α = 0,05). Resultados: O material modificado com nano-SiO2 demonstrou um aumento significativo na perda de peso em comparação com o material acrílico artificial convencional (p ˂ 0,05) enquanto o material modificado com nano-Al2 O3 demonstrou aumento não significativo na perda de peso, exceto no subgrupo 0,5% (p < 0,05). Não há diferenças significativas em relação à alteração da rugosidade após a simulação de desgaste entre todos os grupos testados (p > 0,05). Conclusão: As nanopartículas de nano-Al2 O3 exibem menos efeito negativo que o nanoSiO2 , podendo ser usado com cautela, se necessário. (AU)

Objective: This study aimed to evaluate the wear resistance of acrylic denture teeth containing silicon dioxide (nano-SiO2 ) and aluminum dioxide (nano-Al2 O3 ) nanoparticles. Material and Methods: Poly methyl methacrylate (PMMA) denture tooth material was used to denture tooth material was used to fabricate 84 specimens (n=10) containing nano-SiO2 and nano-Al2 O3 in concentrations 0.1wt%, 0.3wt%, and 0.5wt% of acrylic powder. A two-body wear testing machine and digital microscope were used to measure the changes in weight loss and surface roughness respectively. One-way ANOVA and pair-wise Tukey's post-hoc tests were used for data analysis (α = 0.05). Results: Nano-SiO2 modified teeth material demonstrated a significant increase in weight loss in comparison conventional artificial acrylic teeth material (p ˂ 0.05) while nanoAl2 O3 modified teeth material demonstrated non-significant increase in weight loss except for 0.5% subgroup (p ˂ 0.05). There is no significant differences regarding roughness change after wear simulation among all tested groups (p > 0.05). Conclusion: Nano-Al2 O3 nanoparticles exhibit less negative effect than nano-SiO2 so; it could be used with caution if necessary. (AU)

Effects of SiO2 nanoparticles by intratracheal instilation on major organs of mice in vivo / 吉林大学学报(医学版)

Objective:To study the effects of SiO2 nanoparticles on the organs of mice in vivo after intratracheal instillation, and to provide the basis for safety evaluation of SiO2 nanoparticles. Methods:Forty female BALB/c mice aged 6-8 weeks were randomly divided into control group (saline), low dose of SiO2 group (7 mg·kg-1), middle dose of SiO2 group (21 mg·kg-1), and high dose of SiO2 group (35 mg·kg-1).1 and 15 d after five times of non-exposed intratracheal instilation infection (once every 3 d), the mice were sacrificed and the left lungs,the right kidneys, livers, hearts and spleens were collected and embedded in paraffin.The morphology of tissue sections was observed under light microscope after hematoxylin-eosin (HE) staining.The eyeball blood was obtained and the biochemical indicators of liver and kidndy functions were detected.Results:Compared with control group, there were alveolar interval thickening, inflammatory cell infiltration, and a small amount of small arterial thrombosis in the lungs;granulomatous inflammatory cell infiltration and a small amount of focal necrosis of liver cells in the livers;red pulp enlargement, hyperemia, and more visibly scattered megakaryocytes in the spleens in SiO2 nanoparticles groups in a dose-dependent manner, especially in middle and high doses of SiO2 groups.After 15 d of injection, the damages alleviated with the prolongation of time.There was some inflammatory cell infiltration in the kidney tissue of the mice in SiO2 nanoparticle groups.The biochemical indicator detection results showed that alanine aminotransferase(ALT) and aspartate transaminase(AST) levels in SiO2 nanoparticles groups varied, suggesting the liver cell damages were at different degrees;the changes of urea nitrogen(BUN) and creatinine(Cr) levels in SiO2 nanoparticle groups remindered the kidney function alteration, but there were no obvious dose-and time-dependent effects.Conclusion:Intratracheal instillation of SiO2 nanoparticles can influence the major organs of the mice and mainly displays in the inflammation and injuries in the lung, liver, and spleen.

Pulmonary Toxicity in Rats Caused by Exposure to Intratracheal Instillation of SiO2 Nanoparticles / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>The effect of the silica nanoparticles (SNs) on lungs injury in rats was investigated to evaluate the toxicity and possible mechanisms for SNs.</p><p><b>METHODS</b>Male Wistar rats were instilled intratracheally with 1 mL of saline containing 6.25, 12.5, and 25.0 mg of SNs or 25.0 mg of microscale SiO2 particles suspensions for 30 d, were then sacrificed. Histopathological and ultrastructural change in lungs, and chemical components in the urine excretions were investigated by light microscope, TEM and EDS. MDA, NO and hydroxyproline (Hyp) in lung homogenates were quantified by spectrophotometry. Contents of TNF-α, TGF-β1, IL-1β, and MMP-2 in lung tissue were determined by immunohistochemistry staining.</p><p><b>RESULTS</b>There is massive excretion of Si substance in urine. The SNs lead pulmonary lesions of rise in lung/body coefficients, lung inflammation, damaged alveoli, granuloma nodules formation, and collagen metabolized perturbation, and lung tissue damage is milder than those of microscale SiO2 particles. The SNs also cause increase lipid peroxidation and high expression of cytokines.</p><p><b>CONCLUSION</b>The SNs result into pulmonary fibrosis by means of increase lipid peroxidation and high expression of cytokines. Milder effect of the SNs on pulmonary fibrosis comparing to microscale SiO2 particles is contributed to its elimination from urine due to their ultrafine particle size.</p>

Anti-pepsin activity of silicon dioxide nanoparticles / Actividad antipepsina de nanopartículas de dióxido de silicio / Atividade antipepsina de nanopartículas de dióxido de silício

SiO2NPs as an inhibitor of pepsin enzyme for treatment of gastro-esophageal reflux disease (GERD) were investigated. Silicon dioxide nanoparticles (pepsin coated SiO2NPs) are among the safest nanoparticles that can be used inside the human body. The activity of pepsin before and after the addition of certain amounts of the NPs to the reaction mixture was measured spectrophotometrically. Furthermore, these experiments were repeated at different temperatures, different weights of NPs, and different ionic strengths. The kinetic parameters (Km & Vmax) of the pepsin-catalyzed reactions were calculated from the Lineweaver-Burk plots. The results showed that there is a significant reduction of pepsin activity by SiO2NPs (Vmax of free pepsin = 4.82 U and Vmax of the immobilized pepsin = 2.90 U). The results also indicated that the presence of ionic strength causes remarkable reduction of pepsin activity. It can be concluded the best condition for inhibition of pepsin activity is by using a combinationof SiO2NPs and high concentration NaCl at 37 °C.

Se usaron nanopartículas de dióxido de silicio como inhibidores de la pepsina para el tratamiento del reflujo gastroesofágico (GERD). Estas nanopartículas (SiO2NPs recubiertas de pepsina) son unas de las más seguras y pueden usarse en el cuerpo humano. Se midió a través de espectrofotometría la actividad de la pepsina antes y después de añadir cierta cantidad de NPs a la mezcla reactante. Adicionalmente, se repitieron estas pruebas a diferentes temperaturas, variando el peso de las NPs y la fuerza iónica. Se calcularon los parámetros cinéticos (Km y Vmax) de las reacciones catalizadas con pepsina a través de las gráficas de Lineweaver-Burk. Los resultados mostraron que, usando SiO2NPs (Vmax de pepsina libre = 4.82 U y Vmax de pepsina inmovilizada = 2.90 U) y a través de la presencia de fuerza iónica, la actividad enzimática se reduce significativamente. Se concluye que la mejor condición para inhibir la actividad enzimática es usando una combinación de SiO2NPs y una alta concentración de NaCl a 37 °C.

Foram usadas nanopartículas de dióxido de silício como inibidores da pepsina para o tratamento do refluxo gastroesofágico (GERD). Estas nanopartículas (SiO2NPs cobertas de pepsina) são uma das mais seguras e podem usar-se no corpo humano. Foi medida a atividade da pepsina mediante espectrofotometria antes e depois de agregar certa quantidade de NPs à mistura de reação. Adicionalmente, repetiram-se estas provas a diferentes temperaturas, variando o peso das NPs e a força iónica. Foram calculados os parâmetros cinéticos (Km e Vmax) das reações catalisadas com pepsina a través das gráficas de Lineweaver-Burk. Os resultados mostraram que, usando SiO2NPs (Vmax de pepsina livre = 4.82 U e Vmax de pepsina imobilizada = 2.90 U) e a través da presença de força iónica, a atividade enzimática se reduze significativamente. Foi concluído que a melhor condição para inibir a atividade enzimática é usando uma combinação de SiO2NPs e uma alta concentração de NaCl a 37 °C.

Determination of Uric Acid Based on Chitosan/Ru(bpy) 2+3/Silica Nanoparticles Electrochemiluminescence Sensor / 分析化学

Chitosan-Ru ( bpy ) 2+3 -SiO2 composite nanoparticles ( CRuS NPs ) were prepared by reverse microemulsion method, and based on the Nafion/MCNT composite membrane technology, CRuS NPs were effectively and steadily immobilize on the surface of a glassy carbon electrode to prepare the electrochemiluminescence sensor for uric acid determination. In 0. 1 mol/L PBS (pH 7. 4) buffer solution, when the actuation duration between uric acid and the modified electrode was 15 min, the electrochemiluminescence showed a good linear relationship to the negative logarithm of uric acid concentration in the range of 1. 0 × 10-10-1. 0 × 10-5 mol/L, the linear equation was IECL=-709. 52-202. 74lgC and the correlation coefficient was 0. 9936 with a detection limit of 6. 0 × 10-12 mol/L. The ECL sensor exhibited excellent repeatability and stability, and the RSD for 11 times determination of 1. 0 × 10-8 mol/L uric acid was 2. 9%. The recovery was 98. 5%-103. 5% in the determination of real Uric acid sample.