Effects of Platycodonis Radix-Curcumae Rhizoma on oral nanoparticle uptake and in vitro inhibition against breast cancer metastasis / 中国中药杂志

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.

Effect of polymer nanoparticles on atherosclerotic lesions and the associated mechanisms: a review / 生物工程学报

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.

Mechanism of Der f 1/IGF-1 nanoparticle promoting the production of regulatory T cell / 临床耳鼻咽喉头颈外科杂志

Objective:To prepare PLGA nanoparticles loaded with Der f 1/IGF-1（Der f 1/IGF-1 NPs） and investigate their role in promoting the formation of Treg cells. Methods:NPs coated with Der f 1/IGF-1 were prepared by double emulsion method and their physicochemical properties and cumulative release rate in vitro were analyzed. After pretreatment, BMDC was divided into Saline group, Blank NPs group, Der f 1/IGF-1 group and Der f 1/IGF-1 NPs group. Determination of the expression of IL-10 and TGF-β in BMDC by ELISA. The number of Treg cells was detected by flow cytometry. Results:The results showed that Der f 1/IGF-1 NPs were spherical structures, with good dispersion, particle size less than 200 nm, negative charge and stable slow-release effect of Zeta potential. After BMDC pretreatment, the expression levels of TGF-β and IL-10 in BMDC cells in the Der f 1/IGF-1 NPs group were significantly increased compared with the Blank NPs group, and the difference was statistically significant（P<0.001）. After co-culture with CD4+ T cells, the proportion of Treg cells produced in the Der f 1/IGF-1 NPs group was significantly increased, and the difference was statistically significant（P<0.001）. Conclusion:Der f 1/IGF-1 NPs can induce Treg cell generation in vitro. This study provides a new and more effective method for the reconstruction of immune tolerance dysfunction.

Research progress on the preparation and application of flavonoid nanocrystals / 浙江大学学报·医学版

Flavonoids have been reported to possess significant pharmacological activities,such as antioxidant, anti-inflammatory and anticancer effects. However, the low solubility and low bioavailability limits their clinical application. Nanocrystal technology can solve the delivery problems of flavonoids by reducing particle size, increasing the solubility of insoluble drugs and improving their bioavailability. This article summaries nanosuspension preparation methods and the stabilizers for flavonoid nanocrystals, and reviews the drug delivery routes including oral, Injection and transdermal of flavonoid nanocrystals, to provide information for further research on nanocrystal delivery system of flavonoids.

Research progress on the nucleoside/nucleotide-loaded nanomedicines / 浙江大学学报·医学版

Nucleoside drugs play an essential role in treating major diseases such as tumor and viral infections, and have been widely applied in clinics. However, the effectiveness and application of nucleoside drugs are significantly limited by their intrinsic properties such as low bioavailability, lack of targeting ability, and inability to enter the cells. Nanocarriers can improve the physiological properties of nucleoside drugs by improving drug delivery efficiency and availability, maintaining drug efficacy and system stability, adjusting the binding ability of the carrier and drug molecules, as well as modifying specific molecules to achieve active targeting. Starting from the design strategy of nucleoside drug nanodelivery systems, the design and therapeutic effect of these nanomedicines are described in this review, and the future development directions of nucleoside/nucleotide-loaded nanomedicines are also discussed.

Application of organic nanocarriers for intraocular drug delivery / 浙江大学学报·医学版

The application of intraocular drug delivery is usually limited due to special anatomical and physiological barriers, and the elimination mechanisms in the eye. Organic nano-drug delivery carriers exhibit excellent adhesion, permeability, targeted modification and controlled release abilities to overcome the obstacles and improve the efficiency of drug delivery and bioavailability. Solid lipid nanoparticles can entrap the active components in the lipid structure to improve the stability of drugs and reduce the production cost. Liposomes can transport hydrophobic or hydrophilic molecules, including small molecules, proteins and nucleic acids. Compared with linear macromolecules, dendrimers have a regular structure and well-defined molecular mass and size, which can precisely control the molecular shape and functional groups. Degradable polymer materials endow nano-delivery systems a variety of size, potential, morphology and other characteristics, which enable controlled release of drugs and are easy to modify with a variety of ligands and functional molecules. Organic biomimetic nanocarriers are highly optimized through evolution of natural particles, showing better biocompatibility and lower toxicity. In this article, we summarize the advantages of organic nanocarriers in overcoming multiple barriers and improving the bioavailability of drugs, and highlight the latest research progresses on the application of organic nanocarriers for treatment of ocular diseases.

Effect of nanoparticles of different stiffness combined with menthol/curcumol on mechanical properties of bEnd.3 cells / 中国中药杂志

This study aimed to investigate the effects of nanoparticles PLGA-NPs and mesoporous silicon nanoparticles(MSNs) of different stiffness before and after combination with menthol or curcumol on the mechanical properties of bEnd.3 cells. The particle size distributions of PLGA-NPs and MSNs were measured by Malvern particle size analyzer, and the stiffness of the two nanoparticles was quantified by atomic force microscopy(AFM). The bEnd.3 cells were cultured in vitro, and the cell surface morphology, roughness, and Young's modulus were examined to characterize the roughness and stiffness of the cell surface. The changes in the mechanical properties of the cells were observed by AFM, and the structure and expression of cytoskeletal F-actin were observed by a laser-scanning confocal microscope. The results showed that both nanoparticles had good dispersion. The particle size of PLGA-NPs was(98.77±2.04) nm, the PDI was(0.140±0.030), and Young's modulus value was(104.717±8.475) MPa. The particle size of MSNs was(97.47±3.92) nm, the PDI was(0.380±0.016), and Young's modulus value was(306.019±8.822) MPa. The stiffness of PLGA-NPs was significantly lower than that of MSNs. After bEnd.3 cells were treated by PLGA-NPs and MSNs separately, the cells showed fine pores on the cell surface, increased roughness, decreased Young's modulus, blurred and broken F-actin bands, and reduced mean gray value. Compared with PLGA-NPs alone, PLGA-NPs combined with menthol or curcumol could allow deepened and densely distributed surface pores of bEnd.3 cells, increase roughness, reduce Young's modulus, aggravate F-actin band breakage, and diminish mean gray value. Compared with MSNs alone, MSNs combined with menthol could allow deepened and densely distributed surface pores of bEnd.3 cells, increase roughness, reduce Young's modulus, aggravate F-actin band breakage, and diminish mean gray value, while no significant difference was observed in combination with curcumol. Therefore, it is inferred that the aromatic components can increase the intracellular uptake and transport of nanoparticles by altering the biomechanical properties of bEnd.3 cells.

Formation and characteristics of polystyrene nanoplastic-plant protein corona / 生物工程学报

To investigate the formation of polystyrene nanoplastic-plant protein corona and its potential impact on plants, three differently modified polystyrene nanoplastics with an average particle size of 200 nm were taken to interact with the leaf proteins of Impatiens hawkeri for 2 h, 4 h, 8 h, 16 h, 24 h, and 36 h, respectively. The morphological changes were observed by scanning electron microscopy (SEM), the surface roughness was determined by atomic force microscopy (AFM), the hydrated particle size and zeta potential were determined by nanoparticle size and zeta potential analyzer, and the protein composition of the protein corona was identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The proteins were classified in terms of biological processes, cellular components, and molecular functions to study the adsorption selection of nanoplastics to proteins, investigate the formation and characteristics of polystyrene nanoplastic-plant protein corona and predict the potential impact of protein corona on plants. The results showed that the morphological changes of the nanoplastics became clearer as the reaction time extends, as evidenced by the increase in size and roughness and the enhancement of stability, thus demonstrating the formation of protein corona. In addition, the transformation rate from soft to hard protein corona was basically the same for the three polystyrene nanoplastics in the formation of protein corona with leaf proteins under the same protein concentration conditions. Moreover, in the reaction with leaf proteins, the selective adsorption of the three nanoplastics to proteins with different isoelectric points and molecular weights differed, and the particle size and stability of the final formed protein corona also differed. Since a large portion of the protein fraction in protein corona is involved in photosynthesis, it is hypothesized that the formation of the protein corona may affect photosynthesis in I. hawkeri.

The toxicity of ZnO and CuO nanoparticles on biological wastewater treatment and its detoxification: a review / 生物工程学报

The wide use of ZnO and CuO nanoparticles in research, medicine, industry, and other fields has raised concerns about their biosafety. It is therefore unavoidable to be discharged into the sewage treatment system. Due to the unique physical and chemical properties of ZnO NPs and CuO NPs, it may be toxic to the members of the microbial community and their growth and metabolism, which in turn affects the stable operation of sewage nitrogen removal. This study summarizes the toxicity mechanism of two typical metal oxide nanoparticles (ZnO NPs and CuO NPs) to nitrogen removal microorganisms in sewage treatment systems. Furthermore, the factors affecting the cytotoxicity of metal oxide nanoparticles (MONPs) are summarized. This review aims to provide a theoretical basis and support for the future mitigating and emergent treatment of the adverse effects of nanoparticles on sewage treatment systems.

Biomineralization of lithium nanoparticles by Li-resistant Pseudomonas rodhesiae isolated from the Atacama salt flat

BACKGROUND: The Atacama salt flat is located in northern Chile, at 2300 m above sea level, and has a high concentration of lithium, being one of the main extraction sites in the world. The effect of lithium on microorganism communities inhabiting environments with high concentrations of this metal has been scarcely studied. A few works have studied the microorganisms present in lithium-rich salt flats (Uyuni and Hombre Muerto in Bolivia and Argentina, respectively). Nanocrystals formation through biological mineralization has been described as an alternative for microorganisms living in metal-rich environments to cope with metal ions. However, bacterial lithium biomineralization of lithium nanostructures has not been published to date. In the present work, we studied lithium-rich soils of the Atacama salt flat and reported for the first time the biological synthesis of Li nanoparticles. RESULTS: Bacterial communities were evaluated and a high abundance of Cellulomonas, Arcticibacter, Mucilaginibacter, and Pseudomonas were determined. Three lithium resistant strains corresponding to Pseudomonas rodhesiae, Planomicrobium koreense, and Pseudomonas sp. were isolated (MIC > 700 mM). High levels of S2− were detected in the headspace of P. rodhesiae and Pseudomonas sp. cultures exposed to cysteine. Accordingly, biomineralization of lithium sulfide-containing nanomaterials was determined in P. rodhesiae exposed to lithium salts and cysteine. Transmission electron microscopy (TEM) analysis of ultrathin sections of P. rodhesiae cells biomineralizing lithium revealed the presence of nanometric materials. Lithium sulfide-containing nanomaterials were purified, and their size and shape determined by dynamic light scattering and TEM. Spherical nanoparticles with an average size < 40 nm and a hydro-dynamic size ~ 44.62 nm were determined. CONCLUSIONS: We characterized the bacterial communities inhabiting Li-rich extreme environments and reported for the first time the biomineralization of Li-containing nanomaterials by Li-resistant bacteria. The biosynthesis method described in this report could be used to recover lithium from waste batteries and thus provide a solution to the accumulation of batteries.

Optimization of formulation of paclitaxel nanosuspension encapsulated by erythrocyte membrane based on Box-Behnken method / 中国中药杂志

In view of the longevity and innate immune escape of red blood cells, this study designed the red blood cell membrane-coated paclitaxel nanosuspension [RBC-(PTX)NS] and investigated its physicochemical properties and antitumor effect in vitro. Paclitaxel nanosuspension [(PTX)NS] was prepared by ultrasonic precipitation and then RBC-(PTX)NS by ultrasonic coating. The formulation of(PTX)NS was optimized with Box-Behnken method and indexes of particle diameter, zeta potential, and stability. The morphology, particle diameter, stability, in vitro dissolution, and antitumor effect of(PTX)NS and RBC-(PTX)NS were characterized. The results showed that the particle diameter and zeta potential were(129.38±0.92) nm and(-22.41±0.48) mV, respectively, for the optimized(PTX)NS, while(142.5±0.68) nm and(-29.85±0.53) mV, respectively, for RBC-(PTX)NS. Under the transmission electron microscope,(PTX)NS was spherical and RBC-(PTX)NS had obvious core-shell structure. RBC-(PTX)NS remained stable for 5 days at 4 ℃. The in vitro dissolution test demonstrated that the cumulative release rate of RBC-(PTX)NS reached 79% within 20 min, which was significantly higher than that(25%) of(PTX)NS(P<0.05). As evidenced by MTT assay, RBC-(PTX)NS highly inhibited the proliferation of HepG2 cells in a dose-dependent manner. The cell membrane-coated nano-preparation preparation method is simple and reproducible. It improves the solubility of PTX and endows RBC-(PTX)NS with higher stability and stronger cytotoxicity. Thus, it is a new method for the delivery of PTX via nanocrystallization.

Correlation of the CTD structural domain of hepatitis B virus core protein with the encapsulation effect of indocyanine green / 生物工程学报

Hepatitis B virus core protein (HBc) has become a hot spot in drug carrier protein research due to its natural particle self-assembly ability and ease of modification. The truncation of the C-terminal polyarginine domain (CTD, aa 151-183) of HBc does not affect the self-assembly of the particles. However, it does affect the internal and external charges of the particles, which may subsequently affect drug encapsulation. Thus, the truncated C-terminal polyarginine domain (CTD) of HBc and the inserted RGD peptide were selected to construct and express three HBc variants (RH) encapsulated with ICG (RH/ICG) with different C-terminal lengths to compare the stability and drug activity of their nanoformulations. RH160/ICG was found to have a great advantages in encapsulation efficiency and biological imaging. Compared with other HBc variants, RH160/ICG significantly improved encapsulation efficiency, up to 32.77%±1.23%. Cytotoxicity and hemolysis assays further demonstrated the good biocompatibility of RH160/ICG. Cell uptake and in vivo imaging experiments in mice showed that RH160/ICG could efficiently deliver ICG in tumor cells and tumor sites with good imaging effect. This research provides a new direction for further expanding the diagnosis and treatment application of ICG and development of HBc-based nanoparticle drug carrier platform.

Nanopartículas de prata em bases de próteses de PMMA para controle de atividade microbiana / Silver nanoparticles in PMMA prosthesis bases to control microbial activity

Objetivo:Avaliar in vitro a atividade de Staphylococcus aureus e Candida albicans em bases de próteses convencionais à base de polimetilmetacrilato de metila com nanopartículas de prata incorporadas a sua composição. Métodos: Foi realizado um estudo experimental laboratorial com resinas acrílicas autopolimerizáveis comercialmente disponíveis, Vipi Flash/VIPI e JET/Clássico. Foram confeccionados 80 corpos de prova, divididos em 16 grupos (n = 5), referentes ao tipo de resina, tratamento (incorporação e imersão na solução de nanopartículas de prata) e microrganismo inoculado. As nanopartículas foram sintetizadas com ácido polimetacrílico, nitrato de prata e irradiadas com luz ultravioleta de baixa potência (~8W) por 6 horas, e as suas concentrações idealizadas pelo método de microdiluição em placas para determinação da concentração mínima inibitória frente aos microrganismos selecionados. Verificou-se ação bactericida e fungicida com concentração inicial de 25% e após fator de diluição 12,5%. Resultados: Houve dificuldade de incorporação das nanopartículas na resina acrílica, que pode decorrer da alteração da proporção 3:1 recomendada pelo fabricante ou pela redução ou inativação da ação da nanopartícula de prata pela interação com o polimetilmetacrilato. VIPI com inclusão de nanopartícula obteve menor aderência de biofilme de Candida albicans. Conclusão:A nanopartícula de prata mostrou-se eficaz na sua ação de controle de Candida albicans e Staphylococcus aureus no método de imersão, entretanto, a sua ação antimicrobiana foi comprometida após inclusão nas resinas acrílicas.

Aim:To perform an in vitro evaluation of the activity of Staphylococcus aureus and Candida albicansin conventional prosthesis bases, based on methyl polymethylmethacrylate with silver nanoparticles incorporated into the composition. Methods: An experimental laboratory study was carried out using commercially available self-curing acrylic resins, Vipi Flash/VIPI and JET/Clássico. Eighty specimens were manufactured and divided into 16 groups (n = 5), referent to the resin brand, treatment (incorporation and immersion in the silver nanoparticle solution), and inoculated microorganism. The nanoparticles were synthesized with polymethacrylic acid and silver nitrate, and were irradiated with a low power (~ 8W) ultraviolet light for 6 hours. Their concentrations were idealized by the method of microplate dilution to determine the minimum inhibitory concentration when compared to the selected microorganisms. Bactericidal and fungicidal activities were identified with an initial concentration of 25% and a subsequent dilution factor of 12.5%. Results:It was difficult to incorporate the AgNPs into the acrylic resin, which may well have resulted from the change from the 3:1 proportion recommended by the manufacturer or by reducing or inactivating the action of the silver nanoparticle by interaction with polymethylmethacrylate. VIPI with the inclusion of nanoparticles obtained a lesser Candida albicans biofilm adherence. Conclusion: Silver nanoparticles were effective in controlling Candida albicans and Staphylococcus aureus in the immersion method; however, the antimicrobial activity was compromised after inclusion in acrylic resins.

Efeito da polimerização adicional com micro-ondas na rugosidade superficial de duas resinas compostas / Effect of additional microwave polymerization on the surface rugosity of two compound resins

Introdução: a resina composta é um dos materiais restauradores mais pesquisados na Odontologia, visando melhorias nas suas propriedades e aperfeiçoamento da técnica. Este trabalho tem o objetivo de avaliar a rugosidade superficial de duas resinas compostas, micro-híbrida e nanoparticulada, após a polimerização adicional com micro-ondas. Materiais e métodos: para cada resina composta, foram confeccionados 24 corpos de prova, medindo 0,8 cm de diâmetro interno por 0,2 cm de espessura, dos quais, 12 receberam polimerização adicional com micro-ondas e 12, apenas a polimerização com luz azul visível. Foram estabelecidos quatro grupos: G1 - resina micro-híbrida submetida à polimerização convencional; G2 - resina nanoparticulada submetida à polimerização convencional; G3 - resina micro-híbrida exposta à polimerização adicional em forno de micro-ondas caseiro; e G4 - nanoparticulada exposta à polimerização adicional em forno de micro-ondas caseiro. Os corpos de prova foram lixados em politriz, com o intuito de uniformizar as superfícies, seguindo com leitura no rugosímetro digital Mitutoyo SJ 301. O teste não paramétrico Exato de Mann-Whitney (significância de 5%) foi realizado utilizando a média aritmética (Ra, µm). Conclusão: não houve significância estatística entre os tipos de polimerização e nem entre as diferentes resinas compostas estudadas.(AU)

Introduction: composite resin is one of the most researched restorative materials in dentistry, aiming to improve its properties and improve the technique. This work aims to evaluate the superficial rugosity of two composite resins, microhybrid and nanoparticulate, after additional polymerization with microwaves. Materials and methods: for each composite resin, 24 specimens were made, measuring 0.8cm internal diameter by 0.2cm thick, of which 12 received additional microwave polymerization and 12 visible-blue-light polymerization only. Four groups were established: G1 - microhybrid resin subjected to conventional polymerization; G2 - nanoparticulate resin subjected to conventional polymerization; G3 - microhybrid resin exposed to additional polymerization in a home microwave oven; and G4 - nanoparticulate exposed to additional polymerization in a home microwave oven. The specimens were sanded in a polishing machine in order to standardize the surfaces, followed by reading on the Mitutoyo SJ 301 digital roughness meter. The Mann-Whitney Exact nonparametric test (5% significance) was performed using the arithmetic mean (Ra, µm). Conclusion: there was no statistical significance between the polymerization types and neither among the different composite resins studied.(AU)

Preparation of polymer nanoparticles loaded with Syzygium aromaticum essential oil: an oral potential application / Preparación de nanoparticulas polimericas cargadas con aceite esencial de Syzygium aromaticum: una potencial aplicación oral

Due to the biological activities of Syzygium aromaticum essential oil, its incorporation in methacrylate polymeric (Eudragit E100) nanoparticles (NP), physical characterization, and antimicrobial essays were evaluated. The clove bears great potential for applications in dentistry. The oil was obtained by hydrodistillation and oil loaded NP using the nanoprecipitation method. Particle size and polydispersity index were determined by photon correlation spectroscopy, and physical morphology by electron microscopy. Loading capacity and in vitro eugenol release were evaluated by gas mass chromatography, and the antimicrobial activity of oil loaded-NP was calculated against Streptococcus mutans. Different chemical ingredients were characterized, and eugenol was the principal compound with 51.55%. Polymer content was directly related to NP homogenous size, which was around 150 nm with spherical morphology. A 73.2% loading capacity of eugenol was obtained. Oil loaded NP presented a fickian-type release mechanism of eugenol. Antimicrobial activity to 300 µg/mL was obtained after 24 h.

Debido a las actividades biológicas del aceite esencial de Syzygium aromaticum, se evaluó su incorporación en nanopartículas (NP) de metacrilato polimérico (Eudragit E100), su caracterización y ensayos antimicrobianos. El clavo tiene un gran potencial para aplicaciones en odontología. El aceite se obtuvo por hidrodestilación y las NP cargado de aceite utilizando el método de nanoprecipitación. El tamaño de partícula y el índice de polidispersidad se determinaron mediante espectroscopia de correlación fotónica y su morfología por microscopía electrónica. La capacidad de carga y la liberación de eugenol in vitro se evaluaron mediante cromatografía de gases en masa, y la actividad antimicrobiana se evaluó contra Streptococcus mutans. Se caracterizaron diferentes ingredientes químicos, siendo el eugenol el principal compuesto con 51.55%. El contenido de polímero se relacionó directamente con el tamaño homogéneo de NP, que fue de alrededor de 150 nm con morfología esférica. Se obtuvo un 73,2% de capacidad de carga de eugenol. El aceite cargado en NP presentó un mecanismo de liberación de eugenol de tipo fickiano. La actividad antimicrobiana a 300 µg/mL se obtuvo después de 24 h.

Resistência à flexão de duas resinas compostas diretas após diferentes métodos de polimerização / Flexural strength of two direct composite resins after different polymerization methods

Objetivo: avaliar a influência de diferentes modos de polimerização sobre a resistência à flexão de três pontos de duas resinas compostas. Métodos: foram confeccionadas 88 amostras, sendo divididas em dois grupos, conforme a resina composta utilizada: Filtek Z350 XT e Forma. Os grupos foram subdivididos, de acordo com diferentes modos de polimerização, em: G1- Z350 por 20s a 1.000 mw/cm²; G2- Forma por 20s a 1.000 mw/cm²; G3- Z350 por 20s a 1.000 mw/cm² e micro-ondas por 3 minutos em 450w; G4- Forma por 20s a 1.000 mw/cm² e micro-ondas por 3 minutos em 450w; G5- Z350 por 2 vezes de 3s a 3.200 mw/cm²; G6- Forma por 2 vezes de 3s a 3.200 mw/cm²; G7- Z350 por 2 vezes de 3s a 3.200 mw/cm² e micro-ondas por 3 minutos em 450w; G8- Forma por 2 vezes de 3s a 3.200 mw/cm² e micro-ondas por 3 minutos em 450w. As amostras foram submetidas ao teste de resistência à flexão de 3 pontos, sob taxa de carregamento de 50 N/min, até a falha completa. Os dados foram analisados estatisticamente por análise de variância com dois fatores (two-way ANOVA) e teste de Tukey. Resultados: não houve diferenças estatísticas entre as resinas compostas e os modos de polimerização utilizados. Conclusão: de acordo com os resultados do estudo, e dentre suas limitações, os modos de polimerização não influenciaram a resistência à flexão, independentemente da resina composta testada. (AU)

Objective: to evaluate the influence of different polymerization modes on the three-point flexural strength of two composite resins. Methods: 88 samples were produced and divided into two groups according to the composite resin used: Filtek Z350 XT and Forma. The groups were subdivided according to different polymerization modes into: G1- Z350 for 20 s at 1000 mw/cm²; G2- Forma for 20 s at 1000 mw/cm²; G3- Z350 for 20 s at 1000 mw/cm² and microwave for 3 min at 450w; G4- Forma for 20 s at 1000 mw/cm² and microwave for 3 min at 450w; G5- Z350 2x for 3 s at 3200 mw/cm²; G6- Forma 2x for 3 s at 3200 mw/cm²; G7- Z350 2x for 3 s at 3200 mw/cm² and microwave for 3 min at 450w; and G8- Forma 2x for 3 s at 3200 mw/cm² and microwave for 3 min at 450w. The samples were subjected to the three-point flexural strength test under a 50 N/min loading rate until complete failure. The data were statistically analyzed using two-way analysis of variance (two-way ANOVA) and Tukey's test. Results: there were no statistical differences between the composite resins and the polymerization modes used. Conclusion: according to the study results and within its limitations, the polymerization modes did not affect flexural strength, regardless of the composite resin tested. (AU)

Bioleaching of realgar nanoparticles using the extremophilic bacterium Acidithiobacillus ferrooxidans DLC-5

BACKGROUND: This paper presents micro- and nano-fabrication techniques for leachable realgar using the extremophilic bacterium Acidithiobacillus ferrooxidans (A. ferrooxidans) DLC-5. RESULTS: Realgar nanoparticles of size ranging from 120 nm to 200 nm were successfully prepared using the highenergy ball mill instrument. A. ferrooxidans DLC-5 was then used to bioleach the particles. The arsenic concentration in the bioleaching system was found to be increased significantly when compared with that in the sterile control. Furthermore, in the comparison with the bioleaching of raw realgar, nanoparticles could achieve the same effect with only one fifth of the consumption. CONCLUSION: Emphasis was placed on improving the dissolvability of arsenic because of the great potential of leachable realgar drug delivery in both laboratory and industrial settings

Effect of the incorporation of zinc oxide nanoparticles on the flexural strength of auto- polymerized acrylic resins / Efecto de la incorporación de nanopartículas de óxido de zinc en la resistencia a la flexión de las resinas acrílicas autopolimerizadas

Background: Auto-polymerized acrylic resins are commonly used in many applications in dentistry including in maxillofacial rehabilitation such as interim prostheses, denture repair, reline, orthodontic appliances, record base, among others. These substances, however, have some negative aspects such as poor mechanical properties. Aim: The objective of the current study was to evaluate the effect of incorporating zinc oxide nanoparticles to auto-polymerized acrylic resins on their flexural strength. Materials and methods: Thirty specimens were made from auto-polymerized acrylic resins, divided into three main groups (1 control and 2 experimental). Each group had ten specimens. The two experimental groups comprised the zinc oxide powder at 1% and 2% concentrations, respectively. Acrylic specimens were fabricated with the dimension of 65mm length, 10mm width and 2.5mm thickness according to ISO 1567 specification 1999. Each specimen was subjected to the flexural strength test by a universal testing machine. The crosshead speed for the flexural strength test was 5mm/min until fracture occurred. The SPSS version 16 was utilized for the statistical analysis. The ANOVA and Tukey were used for the comparison among all groups. Results: there was a significant increase (p<0.001) in the flexural strength of the acrylic resins following the addition of zinc oxide particles (control group: 133.27 SD 1.73, ZnO 1%: 154.28 SD 2.90, ZnO 2%: 176.45 SD 0.94). Conclusions: The incorporation of zinc oxide nanoparticles has a significant effect on the flexural strength of auto-polymerized acrylic resins.

Antecedentes: Las resinas acrílicas autopolimerizadas se usan comúnmente en muchas aplicaciones en odontología, incluyendo la rehabilitación maxilofacial, en prótesis provisionales, reparación de prótesis, revestimientos, en aparatos de ortodoncia, bases de registro, entre otros. Estas sustancias, sin embargo, tienen algunos aspectos negativos tales como propiedades mecánicas deficientes. Objetivo: el objetivo del presente estudio fue evaluar el efecto de la incorporación de nanopartículas de óxido de zinc en la resistencia a la flexión de resinas acrílicas autopolimerizadas. Materiales y métodos: Treinta muestras de resinas acrílicas autopolimerizadas fueron hechas, divididas en tres grupos principales (un grupo control y dos experimentales), cada grupo con diez especímenes. Se incorporó polvo de óxido de zinc en los dos grupos experimentales, en concentraciones de 1% y 2%, respectivamente. Las muestras de acrílico se fabricaron con una dimensión de 65mm de longitud, 10mm de ancho y 2,5mm de espesor según la especificación ISO 1567 1999. Cada muestra se sometió a la prueba de resistencia a la flexión mediante una máquina de prueba universal. La velocidad de la cruceta para la prueba de resistencia a la flexión fue de 5mm/min hasta que se produjo la fractura. Se utilizó la versión SPSS 16 para el análisis estadístico. El ANOVA y Tukey se utilizaron para la comparación entre todos los grupos. Resultados: Se observó un aumento significativo (p<0.0 01) en la resistencia a la flexión de las resinas acrílicas luego de la adición de partículas de óxido de zinc (grupo de control: 133,27 SD 1,73 MPa, ZnO 1%: 154,28 SD 2,90 MPa, ZnO 2%: 176,45 SD 0,94 MPa). Conclusiones: La incorporación de nanopartículas de óxido de zinc tiene un efecto significativo en la resistencia a la flexión de las resinas acrílicas autopolimerizadas.

Sistemas de nanopartículas poliméricas II: estructura, métodos de elaboración, características, propiedades, biofuncionalización y tecnologías de auto-ensamblaje capa por capa (layer-by-layer self-assembly) / Polymeric nanoparticle systems: structure, elaboration methods, characteristics, properties, biofunctionalization and self-assembly layer by layer technologies

Los materiales poliméricos han sido ampliamente investigados para aplicaciones biomédicas, teniendo especial relevancia cuando se encuentran en forma de micro- y nano-partículas. Últimamente se ha ampliado su campo de aplicación al ser conjugados con péptidos y ácidos nucleicos, por lo tanto, el interés en el estudio de este tipo de materiales, así como también en la formulación de nanoestructuras funcionalizadas como materiales, dispositivos y vehículos de transporte de agentes terapéuticos ha aumentado. Las recientes investigaciones en nanosistemas se inspiran en fenómenos naturales que estimulan la integración de señales moleculares y la mimetización de procesos a nivel celular, de tejidos y órganos. Tecnológicamente, la capacidad de obtener nanoestructuras esféricas mediante la combinación de materiales que presenten propiedades distintas a las que ningún otro material individual posee por sí solo, es lo que hace que las nanocápsulas sean particularmente atractivas. Las potenciales ventajas de los sistemas de nanopartículas de tipo polimérico se destacan a lo largo de cada parte de este artículo de revisión. El presente artículo aborda los aspectos más relevantes sobre la estructura, composición y algunos métodos de elaboración de los sistemas nanoparticulados. Además, expone algunos de los trabajos más recientes, centrados en sistemas de nanopartículas basados en polímeros dirigidos a la administración de agentes, publicados en artículos especializados de investigación y revisiones durante los últimos años.

Polymeric materials have been extensively investigated for biomedical applications including micro- and nanoparticles. Modern advances have broadened horizons for application with peptides and nucleic acids. Therefore, interests increased in the formulation of materials, devices and vehicles for transporting therapeutic agents in functionalized nanostructures. Recent nano-systems are inspired by natural phenomena that stimulate the integration of molecular signals and the mimicking of natural cellular processes, at tissue and organ levels. Technologically, the ability to obtain spherical nanostructures, which combine different properties, that no other single material possesses on its own, makes nanocapsules particularly attractive. Potential advantages over polymer nanoparticulate systems are highlighted throughout each part of this review article. Here, we address the most relevant aspects of structure, composition and methods of formulation of nanoparticulate systems. In addition, we outline some of the more recent works focusing on nanosized preparations, based on agent-directed polymers, found in specialized research articles that have emerged in the recent years.

Model resin composites incorporating ZnO-NP: activity against S. mutans and physicochemical properties characterization

Abstract Although resin composites are widely used in the clinical practice, the development of recurrent caries at composite-tooth interface still remains as one of the principal shortcomings to be overcome in this field. Objectives To evaluate the activity against S. mutans biofilm of model resin composites incorporating different concentrations of ZnO-nanoparticles (ZnO-NP) and characterize their physicochemical properties. Materials and Methods Different concentrations of ZnO-NP (wt.%): E1=0, E2=0.5, E3=1, E4=2, E5=5 and E6=10 were incorporated into a model resin composite consisting of Bis-GMA-TEGDMA and barium borosilicate particles. The activity against S. mutans biofilm was evaluated by metabolic activity and lactic acid production. The following physicochemical properties were characterized: degree of conversion (DC%), flexural strength (FS), elastic modulus (EM), hardness (KHN), water sorption (Wsp), water solubility (Wsl) and translucency (TP). Results E3, E4, E5 and E6 decreased the biofilm metabolic activity and E5 and E6 decreased the lactic acid production (p<0.05). E6 presented the lowest DC% (p<0.05). No significant difference in FS and EM was found for all resin composites (p>0.05). E5 and E6 presented the lowest values of KHN (p<0.05). E6 presented a higher Wsp than E1 (p<0.05) and the highest Wsl (p<0.05). The translucency significantly decreased as the ZnO- NP concentration increased (p<0.05). Conclusions The incorporation of 2 - 5 wt.% of ZnO-NP could endow antibacterial activity to resin composites, without jeopardizing their physicochemical properties.