Research progress on occupational exposure to carbon nanotubes and carbon nanotubes-induced pulmonary fibrosis / 中国职业医学

Carbon nanotube (CNT), as a new nanomaterial, is widely used in commercial and industrial production. The occupational exposure of workers involved in CNT production and manufacturing is gradually increasing. CNT mainly enters the human body through the respiratory system, and mainly exerts toxic effects on the respiratory system, including decreased lung function, lung inflammation, and pulmonary fibrosis. Pulmonary fibrosis, as one of the important diseases caused by CNT exposure, has attracted attention and been studied. The process of pulmonary fibrosis induced by CNT has four stages: acute pulmonary inflammatory response, structural destruction and parenchymal injury of lung tissue, impaired lung tissue repair and pulmonary fibrosis. The molecular mechanisms of CNT induced pulmonary fibrosis may be related to cell proliferation, epithelial-mesenchymal transition, fibroblast-myofibroblast differentiation, pulmonary inflammation, immune response and oxidative stress. In the future, it is needed to explore the pathogenesis of pulmonary fibrosis caused by CNT through animal experiments, and carry out large sample and multi-center epidemiological studies for verification.

A novel method for detecting circulating tumor cells immunity based on micro-nano technique / 生物工程学报

This study was to develop a new method for detecting circulating tumor cells (CTCs) with high sensitivity and specificity, therefore to detect the colorectal cancer as early as possible for improving the detection rate of the disease. To this end, we prepared some micro-column structure microchips modified with graphite oxide-streptavidin (GO-SA) on the surface of microchips, further coupled with a broad-spectrum primary antibody (antibody1, Ab1), anti-epithelial cell adhesion molecule (anti-EpCAM) monoclonal antibody to capture CTCs. Besides, carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) were coupled with colorectal cancer related antibody as specific antibody 2 (Ab2) to prepare complex. The sandwich structure consisting of Ab1-CTCs-Ab2 was constructed by the microchip for capturing CTCs. And the electrochemical workstation was used to detect and verify its high sensitivity and specificity. Results showed that the combination of immunosensor and micro-nano technology has greatly improved the detection sensitivity and specificity of the immunosensor. And we also verified the feasibility of the immunosensor for clinical blood sample detection, and successfully recognitized detection and quantization of CTCs in peripheral blood of colorectal cancer patients by this immunosensor. In conclusion, the super sandwich immunosensor based on micro-nano technology provides a new way for the detection of CTCs, which has potential application value in clinical diagnosis and real-time monitoring of disease.

The effects of TiO2 nanotubes on bond strength and radiopacity of a self-adhesive resin cement in self-curing mode / Os efeitos de nanotubos de TiO2 na resistência de união e radiopacidade de um cimento resinoso auto-adesivo no modo auto-polimerizável

Objective: The aim of this in vitro study w as t o analyze the influence of the titanium dioxide nanotubes i n a self-cure mode polymerization of a dual resin luting agent through push out bond strength and radiopacity tests. Material and Methods: After mixed with a commercial du al self-adhesive resin cement, three concentrations o f tit anium dioxide nanotubes (0.3, 0.6, and 0.9% by weight) we re analyzed in self-curing mode. T he bond strength to bovine root dentin and fi berglass posts was assessed with the push out bond str ength t est and was evaluated in three thirds (cervical, middle and apical) (n=10), followed by failure mode analysis (SEM), and the ISO standard 9917-2 was followed for radiopacity test (n=10). Data were statistically analyzed by one-way ANOVA test, followed by Tukey's test (α=0.05). Results: Reinforced self-adhesive resin cement with 0.6% titanium dioxide nanotubes showed significant difference compared to the control gr oup for push out test (p=0.00158). The modified groups did not s how significant difference among thirds (p=0.782). Radiopacity sh owed higher value for group w ith 0.9% titanium dioxide nanotubes in comparison w ith control group (p<0.001). Conclusion: The addition of titanium dioxide nanotubes to a self-adhesive resin cement increased the bond strength to dentin and radiopacity values in the self-cure polymerization mode (AU)

Objetivo: O objetivo deste estudo in vitro foi analisar a influência de nanotubos de dióxido de titânio na polimerização química de um agente cimentante resinoso dual através de testes de resistência à união e radiopacidade. Material e Métodos: Após misturado com um cimento resinoso auto-adesivo comercial, três concentrações de nanotubos de dióxido de titânio (0,3, 0,6 e 0,9% em peso) foram analisadas. A resistência da união para a dentina da raiz bovina e os pinos de fibra de vidro foi avaliada pelo teste de push-out e avaliada em três terços (cervical, médio e apical) (n = 10), seguido pelo análise de modo de falha (MEV) e a norma ISO 9917-2 foi seguido para teste de radiopacidade (n = 10). Os dados foram analisados estatisticamente pelo teste ANOVA um fator seguido do teste de Tukey (α = 0,05). Resultados: O cimento resinoso auto-adesivo reforçado com nanotubos de dióxido de titânio a 0,6% mostrou diferença significativa em comparação com o grupo controle para teste de push-out (p=0,00158). Os grupos modificados não mostraram diferença significativa entre os terços (p=0,782). A radiopacidade mostrou maior valor para o grupo com nanotubos de dióxido de titânio 0,9% em comparação com o grupo controle (p<0,001). Conclusão: A adição de nanotubos de dióxido de titânio a um cimento resinoso auto-adesivo aumentou a os valores de resistência de união à dentina e radiopacidade no modo de polimerização química do agente cimentante (AU)

Effects of Interaction Between Carbon Nanotubes on Membrane-Wrapped Carbon Nanotubes / 医用生物力学

Objective For the system of two single-walled carbon nanotubes (CNTs) placed in parallel onto a cell membrane, effects of the interaction between carbon nanotubes on wrapping manner of carbon tubes by the membrane were investigated, and the energy-optimized configurations were obtained. Methods A physical model for membrane-wrapped CNTs considering the interaction between two CNTs, and parameters describing the morphology of cell membrane and positions of CNTs were introduced. The Helfrich model based on continuum mechanics was used to calculate the membrane’s bending energy and the Lennard-Jones potential was introduced to describe the interaction between CNTs. Free energy of the system at different distances of NTs was calculated by the look-up table method, and the typical configurations of the membrane-wrapped CNTs was obtained. Results Compared with the case wherein the interaction between CNTs was not considered, the free energy profile of the system significantly changed. Deep well appeared on energy curve, when the distance between CNTs of carbon was 0.3 times of the tube diameter; as the distance between CNTs increased, the energy returned to the case wherein the interaction between CNTs was not considered. Conclusions With introduction of the interaction between CNTs, the wrapping manner of CNTs by the cell membrane changed, and the two CNTs tended to contact during their endocytosis. These results provide theoretical references for understanding and developing novel nanotube-based system for drug delivery.

Research Progress of Intercellular Mitochondrial Transfer in the Development of Hematological Malignant Tumors --Review / 中国实验血液学杂志

In recent years, studies have found that mitochondrial transfer between leukemic cells and different types of cells in their bone marrow microenvironment, especially mesenchymal stem cells, plays a key role in the occurrence, development and drug resistance of hematological malignant tumors. This paper mainly introduces the role and latest research progress of mitochondrial transfer in acute and chronic myeloid leukemia, acute lymphoblastic leukemia and multiple myeloma, and briefly describes the mechanism of drug resistance caused by mitochondrial transfer in leukemic cells during chemotherapy. The aim is to provide a new idea and theoretical basis for using intercellular mitochondrial transfer as a potential therapeutic target.

Challenges in the use of nanostructures as carriers of nucleic acids in clinical practice

ABSTRACT The delivery of nucleic acids to cells is considered a crucial step for the success of genetic modifications aimed at therapeutic purposes or production of genetically modified animals. In this context, nanotechnology is one of the most promising fields of science, with the potential to solve several existing problems. Nanostructures have desirable characteristics to be used as carriers, such as nanometric size, large surface area, cell internalization capacity, prolonged and controlled release, among others. Genetically modified animals can contribute to the production of biopharmaceuticals, through the expression of high-associated-value molecules. The production of these animals, also known as biofactories, further enhances Brazilian agribusiness, since it allows adding value to the final product, and favors the integration between the agricultural market and the pharmaceutical sector. However, there is a growing concern about the safety and possible harmful effects of nanostructures, since data on the safe use of these materials are still insufficient. The objective of this review was to address aspects of the use of nanostructures, mainly carbon nanotubes as nucleic acid carriers, aiming at the production of genetically modified animals, with the certainty that progress in this field of knowledge depends on more information on the mechanisms of interaction between nanostructures, cells and embryos, as well as on its toxicity.

TiO2 nanotube-containing glass ionomer cements display reduced aluminum release rates

Abstract Titanium dioxide nanotubes (TiO2-nts) were incorporated into a glass ionomer cement (GIC) with improved mechanical properties and antibacterial activity. The aims of the present in vitro study were to define the elemental characterization, aluminum (Al) release rate, and initial working time for GIC reinforced with TiO2-nts, in an experimental caries model. TiO2-nts were incorporated into GIC powder components at 5% by weight, and compared with unblended GIC. Experimental approaches used energy-dispersive spectrometry (EDS), atomic absorption spectrophotometry (AAS), and brightness loss to define surface element properties, Al release rates, and initial working time, respectively. Statistical analysis was performed by 2-way ANOVA, Tukey's test, generalized linear models, and Student's t test (a = 0.05). EDS data analysis revealed that TiO2-nts incorporated into GIC had no significant impact on the typical elemental composition of GICs in an in vitro caries model. Regarding the demineralizing solution, GIC with TiO2-nt significantly decreased the Al release rate, compared with the control group (p < 0.0001). Moreover, TiO2-nt incorporated into GIC did not alter the initial working time of the material (p > 0.05). These findings add information to our scientific body of knowledge concerning the potential impact of TiO2-nt on the performance of conventional GICs.

Ácido L-poliláctico (PLA) y na-notubos de carbono de pared múltiple (NTCPM) con potenciales aplicaciones industriales / L-polylactic acid (PLA) and multi-walled carbon nano-tubes (CNTMW) with potential industrial applications / Ácido L-polilático (PLA) e na-notubos de carbono de paredes múltiplas (NTCPM) com possíveis aplicações industriais

Resumen En términos generales, es bien conocida la cualidad que poseen algunos polímeros de cambiar sus propiedades físicas y químicas finales mediante la adición de nanopartículas a la matriz polimérica para producir un material compuesto (MC). Esta investigación está basada en la obtención de un MC a partir de ácido poliláctico (PLA) y nanotubos de carbono de pared múltiple (NTCPM), muy empleado en la industria del envasado y dispositivos biomédicos, con el fin de ampliar su perfil industrial. Se desarrollaron cuatro mezclas de PLA y NTCPM, y se empleó polietilenglicol (PEG) como plastificante. Se evaluaron sus propiedades morfológicas, térmicas, mecánicas, termo-mecánicas, espectroscópicas, ángulo de contacto y cristalográficas. Se observó que los MCs presentaron degradación térmica a temperaturas inferiores a la matriz sin NTCPM, así como un aumento en el módulo de flexión y tensión en algunas de las muestras. Así mismo, se observó que los NTCPM pueden aumentar la cristalinidad del material y que, en algunos casos, se incrementa su rigidez, actuando como un aditivo útil para aplicaciones de mayor esfuerzo mecánico que la matriz. Del efecto de agregar PEG en los MC, se determinó que los NTCPM no restringen la movilidad de las cadenas poliméricas y se da un efecto plastificante, lo que permite mayor movilidad de la zona amorfa de las cadenas de polímero, como indica la literatura consultada. Finalmente, se concluyó que a mayores contenidos de NTCPM, se generan mejores valores en el módulo de flexión, esfuerzo máximo de flexión, módulo de elongación, esfuerzo de carga máxima y esfuerzo de ruptura, entre otras propiedades evaluadas.

Abstract The quality of some polymers to change their final physical and chemical properties by adding nanoparticles to the polymer matrix to produce a composite material (MC) is well known. This research is based on obtaining a MC from polylactic acid (PLA) and multi-walled carbon nanotubes (CNTMW), widely used in the packaging industry and biomedical devices, in order to expand its industrial profile. Four mixtures of PLA and CNTMW were developed, and polyethylene glycol (PEG) was used as a plasticizer. Their morphological, thermal, mechanical, thermo-mechanical, spectroscopic, contact angle, and crystallographic properties were evaluated. It was observed that the composites showed thermal degradation at temperatures below the matrix without CNTMW, as well as an increase in the modulus of flexion and tension in some of the samples. Likewise, it was observed that the CNTMW can increase the crystallinity of the material and that, in some cases, its rigidity is increased, acting as a useful additive for applications of greater mechanical stress than the matrix. From the effect of adding PEG in the composites, the CNTMW do not restrict the mobility of the polymer chains and a plasticizing effect occurs, which allows greater mobility of the amorphous zone of the polymer chains. In general terms, it was concluded that at higher CNTMW contents, better values were generated in the flexural modulus, maximum flexural stress, elongation modulus, maximum load stress and rupture stress, among other evaluated properties.

Resumo Alguns polímeros têm a propriedade de alterar suas propriedades físicas e químicas finais, adicionando nanopartículas à matriz polimérica para produzir um composto. Esta pesquisa baseia-se na obtenção de composto partir de ácido polilático (PLA) e nanotubos de carbono de paredes múltiplas (MWCNT), amplamente utilizado na indústria de embalagens e dispositivos biomédicos, a fim de expandir seu perfil industrial. Foram desenvolvidas quatro misturas de PLA e MWCNT e o polietilenoglicol (PEG) foi usado como plastificante. Foram avaliadas suas propriedades morfológicas, térmicas, mecânicas, termo-mecânicas, espectroscópicas, ângulo de contato e cristalográficas. Observou-se que os compostos apresentaram degradação térmica em temperaturas abaixo da matriz sem MWCNT, além de aumento no módulo de flexão e tensão em algumas das amostras. Da mesma forma, observou-se que o MWCNT pode aumentar a cristalinidade do material e que, em alguns casos, sua rigidez é aumentada, atuando como um aditivo útil para aplicações de maior tensão mecânica que a matriz. A partir do efeito da adição de PEG nos compostos, determinou-se que o MWCNT não restringe a mobilidade das cadeias poliméricas e ocorre um efeito plastificante, que permite maior mobilidade da zona amorfa das cadeias poliméricas. Em termos gerais, concluiu-se que, com maiores teores de MWCNT, melhores valores foram gerados no módulo de flexão, tensão máxima de flexão, módulo de alongamento, tensão de carga máxima e tensão de ruptura, entre outras propriedades avaliadas.

Radiosensitivity enhancement effect of FePd@CNTs nanocomposites on MCF-7 cells / 中华放射肿瘤学杂志

Objective:To evaluate the radiosensitivity enhancement effect of FePd@CNTs nanocomposites on human breast cancer MCF-7 cells.Methods:FePd@CNTs nanocomposites were synthesized by chemical reduction method. Transmission electron microscope and energy dispersive spectrometer were utilized to characterize the surface morphology and chemical composition of FePd@CNTs nanocomposites. The compatibility of FePd@CNTs nanocomposites with human normal breast epithelial MCF-10A cells was determined by CCK-8 assay. The radiosensitivity enhancement effect of FePd@CNTs nanocomposites on MCF-7 cells was assessed by CCK-8 assay, flow cytometry and clony formation assay.Results:FePd nanospheres were successfully modified on the surface of CNTs by chemical reduction method. FePd@CNTs nanocomposites showed a low toxicity to MCF-10A cells (IC 50=738.3 μg/m), and effectively enhanced the effect of X-ray radiation on MCF-7 cells (sensibilization ratio=1.22). Conclusion:FePd@CNTs nanocomposites exhibit a promising potential for treating breast cancer and enhancing radiosensitivity effect.

A novel biomimetic micro/nano hierarchical interface of titanium enhances adhesion, proliferation and osteogenic differentiation of bone marrow mesenchymal cells / 口腔疾病防治

Objective @#To design a novel biomimetic micro/nano hierarchical interface on endosseous titanium implants and investigate its effect on the biological activity of bone marrow mesenchymal cells.@*Methods@#Electrochemical anodization and spark plasma sintering were used to modify smooth titanium (untreated Ti group) with a microporous trabecular bone-like architecture (micro-Ti group) and TiO2 nanotube architecture (nano-TiO2 group). Additionally, electrochemical anodization was employed to prepare TiO2 nanotubes on microporous trabecular bone-like architectures, which formed a novel biomimetic hierarchical interface (micro/nano-TiO2 group). Four groups of titanium samples were characterized by field emission scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle (CA). Bone marrow mesenchymal cells (BMMCs) were seeded on four groups of titanium samples. Scanning electron microscopy (SEM) was employed to observe cell morphology. Cell proliferation was determined by MTT assay. The expression of focal adhesion proteins (F-actin; vinculin; osteocalcin, OCN; osteopontin, OPN) were observed under a confocal laser scanning microscope (CLSM). The mRNA expression levels of osteogenic factors (runt-related transcription factor 2, RUNX2; osteocalcin, OCN; osteopontin, OPN; collagen I, COL I) were assessed by qRT-PCR.@*Results@# The micro/nano- TiO2 group featured a hydrophilic surface (CA=9° ± 2.1°). The results of the MTT assay indicated that the relative cell proliferation rates for the nano- TiO2 and micro/nano-TiO2 samples were significantly increased compared with those for the untreated-Ti and micro-Ti samples (P＜0.001) after 5-9 days. The ALP results indicated that the micro/nano-TiO2 sample gained the highest value at 14 days. After 72 h of incubation, the expression of osteocalcin (OCN) and osteopontin (OPN) on micro/nano-TiO2 was the strongest. After 24 h incubation, the expression of F-actin on micro/nano-TiO2 was the strongest. In comparison with untreated-Ti and micro-Ti samples,the mRNA expression levels of all the osteogenic factors (runt-related transcription factor 2, RUNX2; osteocalcin, OCN; osteopontin, OPN; Collagen I, COL I) were markedly increased on the nano-TiO2 and micro/nano-TiO2 samples, the mRNA expression levels of collagen I (COL I) were significantly different between the nano-TiO2 and micro/nano-TiO2 samples versus the untreated-Ti and micro-Ti samples (P＜0.001). @* Conclusion@#The novel biomimetic micro/nano hierarchical interface has a positive effect on cell attachment, viability and osteogenic differentiation of bone marrow mesenchymal cells.

Primary culture macrophages from fish as potential experimental model in toxicity studies with multiwalled carbon nanotubes

Multiwalled carbon nanotube (MWCNT) has been broadly used in several sectors of society. This material when exposed to the environment might reach the aquatic animals and cause toxic effects. Here, it was evaluated the MWCNTs toxicity in melanomacrophages primary culture that was submitted to 1 µ gm L-1 MWCNTs for 24 hours. After exposition to MWCNT, 48 and 59% liver and spleen melanomacrophages were healthy, respectively. The control group presented 85% viability. Phagocytosis activity of melanomacrophages was observed by presence of black inclusions in cytoplasm. The findings indicate MWCNT was cytotoxic to melanomacrophages, where its release and effect into aquatic environment must be more studied. Finally, the melanomacrophages present large potential as experimental model for evaluation of carbon-based nanomaterial toxicity.

Effects of length and chemical modification on the activation of vascular endothelial cells induced by multi walled carbon nanotubes / 北京大学学报(医学版)

OBJECTIVE@#To investigate the effects of multi-walled carbon nanotubes (MWCNTs) with different length or chemical modification on endothelial cell activation and to explore the role of nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome.@*METHODS@#MWCNTs were characterized by dynamic light scattering (DLS) after being suspended in culture medium. The immortalized mouse cerebral microvascular endothelial cell line b.End3 was treated with short MWCNTs (S-MWCNT, 0.5 to 2 μm), long MWCNTs (L-MWCNT, 10 to 30 μm) and the above long MWCNTs functionalized by carboxyl-(L-MWCNT-COOH), amino-(L-MWCNT-NH2) or hydroxyl-(L-MWCNT-OH) modification. Cytotoxicity of MWCNTs in b.End3 cells was determined by cell counting kit-8 (CCK-8) assay and lactate dehydrogenase (LDH) release assay, and non-toxic low dose was selected for subsequent experiments. Effects of all types of MWCNTs on the endothelial activation of b.End3 were determined by the measurement of vascular cell adhesion molecule-1 (VCAM-1) concentration in cell supernatant and adhesion assay of human monocytic cell line THP-1 to b.End3.To further elucidate the mechanism involved, the protein expressions of nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3(NLRP3) in cells treated with S-MWCNT, L-MWCNT and L-MWCNT-COOH were measured by Western blot.@*RESULTS@#At a higher concentration (125 μg/cm2) and treated for 24 h, all types of MWCNTs significantly inhibited viability of b.End3 cells. At a sub-toxic concentration (6.25 μg/cm2), all types of MWCNTs treated for 12 h significantly induced the activation of b.End3 cells, as evidenced by the elevated VCAM-1 release and THP-1 adhesion. Compared with S-MWCNT, L-MWCNT significantly promoted endothelial cell activation. L-MWCNT and L-MWCNT-COOH activated b.End3 cells to a similar extent. Furthermore, treatment with S-MWCNT, L-MWCNT and L-MWCNT-COOH increased NLRP3 expression in a time-dependent manner at 6.25 μg/cm2. Compared with S-MWCNT, cells treated with L-MWCNT for 4 h and 12 h exhibited significantly increased protein expressions of NLRP3. However, no significant differences were detected in the level of NLRP3 protein in cells treated with L-MWCNT and L-MWCNT-COOH.@*CONCLUSION@#Compared with the surface chemical modification, length changes of MWCNTs exerted more influence on endothelial cell activation, which may be related to the activation of NLRP3 inflammasome. Our study contributes further understanding of the impact of MWCNTs on endothelial cells, which may have implications for the improvement of safety evaluation of MWCNTs.

Compósito odontológico carregado com nanotubos de carbono: caracterização e ensaios biológicos / Dental composite loaded with carbon nanotube: characterization and biological tests

Nanotubos de carbono (NTC) são materiais promissores ao melhoramento de compósitos odontológicos. Entretanto, a homogeneização e o comprometimento estético dessas associações ainda são um desafio. Além disso, até o momento, não foram exploradas composições capazes de induzir respostas teciduais endógenas de reparo. Neste sentido, este estudo teve como objetivo incorporar duas concentrações de NTC de paredes múltiplas (NTCPM), as growth, numa rede polimérica de metilmetacrilato no intuito de investigar as propriedades químicas, mecânicas e biológicas desse novo biomaterial. Produziu-se uma formulação Bis-GMA e TEGDMA (2:1) com 0%; 0,001%; ou 0,01% de NTCPM. Os compósitos foram caracterizados por meio de termogravimetria, espectroscopia no infravermelho com refletância total atenuada (FTIR-ATR), microscopia eletrônica de varredura (MEV). Testes de compressão, flexão, sorção-solubilidade (norma ISO 4049:2009), estabilidade de cor, grau de conversão, e microdureza foram aplicados aos diferentes grupos experimentais. Finalmente, ensaios antimicrobianos em S. mutans (ATCC 25175) (suspensão e biofilme) e ensaios em queratinócitos (HaCat) (citotoxicidade) e pré-osteoblastos (MC3T3) (citotoxicidade/diferenciação) foram utilizados para avaliação de citocompatibilidade e bioatividade. Utilizou-se luz LED (470 nm e 800 mW/cm2) para fotoativar os monômeros. De acordo com ANOVA seguido pelo post-hoc de Tukey, adotando um nível de significância de 5%, a resistência à compressão foi significativamente maior no grupo 0,001% (125,66 MPa) que no grupo controle (46,94 MPa). A resistência flexural foi significativamente maior no grupo 0,001% (51,74 MPa) quando comparado ao grupo 0,1%. Não houve variação nos valores de sorção, solubilidade e estabilidade de cor entre os grupos avaliados. O grau de conversão foi menor nos grupos com NTCPM quando comparado com o grupo controle, e a microdureza Knoop menor na concentração 0,001% quando comparada aos demais grupos. O exame superficial mostrou maior formação de aglomerados de nanotubos nas amostras mais concentradas. O grupo contendo 0,001% NTCPM apresentou atividade antibiofilme quando comparado com o grupo controle e 0,01%. Todas as concentrações apresentaram citotoxicidade nas HaCat após 7 dias, mas a incorporação de NTCPM favoreceu a mineralização de MC3T3 em relação ao controle. Concluiu-se que tanto as propriedades mecânicas como as biológicas apresentaram melhoras com a adição de baixa concentração de NTCPM (0,001%). A adição de 0,001% de NTCPM parece promissora para incorporação em compósitos odontológicos.

Carbon nanotubes (CNT) are candidates for the improvement of dental composites. However, the homogenization and aesthetic commitment of CNT' addition are still a challenge. Moreover, heretofore, there is no study investigating compositions capable of inducing tissue responses towards repair. In this sense, this study aimed to incorporate two concentrations of multiple walls CNT (MWCNT), as growth, in a polymeric network. The chemical, mechanical, and biologicals properties of this experimental biomaterials were assessed. A Bis-GMA and TEGDMA (2:1) base was produced with 0%; 0.001%; or 0.01% MWCNT. The composites were assessed using thermogravimetry, infrared spectroscopy with attenuated total reflectance (FTIR-ATR), scanning electron microscopy (SEM), and were also subjected to compression, bending, sorption-solubility tests in accordance with ISO 4049 :2009, color stability, degree of conversion, microhardness and also to antimicrobial assays in S. aureus (ATCC 25193) (halo formation), S. mutans (ATCC 25175) (biofilm adhesion) and biological assays in keratinocytes (HaCat ) (cytotoxicity) and pre-osteoblasts (MC3T3) (differentiation). LED light (470 nm and 800 mW / cm2) was used to light-cure the monomers. According to ANOVA followed by Tukey's post-hoc, adopting a significance level of 5%, the compressive strength was significantly higher for the 0.001% group (125.66 MPa) than control (46.94 MPa). Flexural strength was also more significant in the 0.001% (51.74 MPa) group than the 0.1% group. There was no significant difference in the values of sorption and solubility and color stability between the evaluated groups. The degree of conversion was lower in the groups with NTCPM when compared to the control group, however the Knoop microhardness was higher in the group with the highest concentration of NTCPM and lower in the group with the lowest concentration when compared to the control group. Despite not showing bacterial inhibition halo formation in any of the groups, the groups containing NTCPM showed a decrease in biofilm adhesion when compared to the control group. All groups shown cytotoxicity on HaCat, but the addition of MWCNT favored MC3T3 mineralization over control. It was concluded that both mechanical and biological properties improved with the addition of low concentration of MWCNT (0.001%). The addition of 0.001% MWCNT looks promising for incorporation in dental composites.

Effect of Addition of Graphene and Carbon Nanotubes on Flexural Strength of Polymethylmethacrylate- A Comparative In-Vitro Study.

Heat polymerized denture base resins are a popular choice in prosthodontics for fabrication of partial or complete dentures, cranioplasts, hybrid implant prosthesis, and maxillofacial prosthetics. The wide utility of these materials can be attributed to their favourable mechanical properties. Despite the popularity gained by them, clinicians often encounter suboptimal flexural strength resulting in frequent fracture of the fabricated prosthesis. The purpose of this study was to compare the flexural strength (FS) of Polymethylmethacrylate (PMMA) modified using micro-additions of Multi-Walled Carbon Nanotubes (MWCNT) and Graphene Oxide (GO) as fillers respectively with PMMA having no micro-additions.METHODSThis is an in-vitro comparative study. Sixty samples of PMMA were divided in three groups of 20 each containing: Group 1: no micro additions (control group), Group 2: 0.5 wt% MWCNT in monomer of PMMA resin, Group 3: 0.5 wt% GO in monomer of PMMA resin. MWCNT and Graphene oxide were dispersed in Methylmethacrylate (monomer) respectively by ultrasonic agitation. Monomer and polymer were mixed in the ratio of 1:3. The samples were heat polymerised. Finished samples were subjected to 3-point bending test for checking their flexural strength. The results were statistically compared using one-way ANOVA followed by post hoc Bonferroni corrected paired T test for inter-group comparisons.RESULTSThe highest mean Flexural Strength of 36.5 MPa was recorded in Group 2 (MWCNT) followed by 31.55 MPa in Group 1 (control) and the least 29.72 MPa in Group 3 (Graphene Oxide) respectively. Intergroup comparisons revealed significant difference between Group 1 (control) & Group 2 (MWCNT) with “p=0.011” and between Group 2 (MWCNT) & Group 3 (Graphene Oxide) with “p<0.001”. However, no significant difference was found between Group 1 (control) and Group 3 (Graphene Oxide) with “p= 0.803”.CONCLUSIONSThe addition of 0.5 wt% MWCNT to PMMA is an easy, effective and economical step towards increasing the flexural strength and thus, decreasing the incidence of prosthesis fracture, when compared to 0.5 wt% graphene oxide or no micro additions.

Acid-functionalized single-walled carbon nanotubes alter epithelial tight junctions and enhance paracellular permeability

The T(EB4)Nta, T(IBj5)Nta, and T(B362i)NtA strains were constructed by introgressing the insertionaltranslocations EB4, IBj5, and B362i from Neurospora crassa into the related species N. tetrasperma. Theprogeny from crosses of T(IBj5)Nta and T(B362i)NtA with opposite mating-type derivatives of the standard N.tetrasperma strain 85 exhibited a unique and unprecedented transmission ratio distortion (TRD) that disfavoredhomokaryons produced following alternate segregation relative to those produced following adjacent-1 segregation. The TRD was not evident among the [mat A ? mat a] dikaryons produced following either segregation. Further, crosses of the T(IBj5)Nta and T(B362i)NtA strains with the Eight spore (E) mutant showed anunusual ascus phenotype called ‘max-4’. We propose that the TRD and the max-4 phenotype are manifestations of the same Bateson-Dobzhansky-Muller incompatibility (BDMI). Since the TRD selects against 2/3 ofthe homokaryotic progeny from each introgression cross, the BDMI would have enriched for the dikaryoticprogeny in the viable ascospores, and thus, paradoxically, facilitated the introgressions.

Target-specific gene delivery in plant systems and their expression: Insights into recent developments

High-yielding Indian cotton varieties are not amenable for regeneration and transformation because they arerecalcitrant in nature. In this work, we have developed Narasimha (NA1325) cotton variety by introducing threeCrygenes driven by three different promoters conferring insect resistance. The meristematic region of embryo axisexplants were infected and co-cultivated with Agrobacterium tumefacience (LBA4404) harbouring pMDC100vector with three Cry gene cassettes (a-globulin : Cry2Ab, DECaMV35s : Cry1F and nodulin : Cry1Ac) with Npt IIas a selectable marker gene. Out of 1010 embryo axes explants infected, 121 (T0) regenerated under two rounds ofkanamycin selection medium. About 2551 T1 seeds were collected from 111 T0 plants and these seeds screened againwith kanamycin at seedling stage. The transgenic plants were characterized by PCR, real time quantitative PCR,lateral flow strip protein assay and insect bioassay. Out of 145 kanamycin resistant plants (T1), twelve showedamplification of all four transgenes: Npt II, Cry2Ab, Cry1F and Cry1Ac through PCR with expected amplicons as395, 870, 840 and 618 bp, respectively. Further, lateral flow strip test revealed Cry1F and Cry1Ac proteinsaccumulated in 12 plants, whereas Cry2Ab protein was detected in eight only. The transcripts of all three Cry geneswere accumulated significantly higher in transgenic plants at T2 generation. The transgenic lines showed effectiveresistance against Helicoverpa armigera and Spodoptera litura larvae. The T2 line L-3 exhibited highest percentageof insect mortality, in which transcripts of all cry genes were accumulated higher than other plants. The transgeniccotton plants carrying triple Cry genes could be an excellent germplasm resource for the breeders for introgressions.

Detection of Rutin in Sophorae Immaturus Flos with Electrochemical Sensor Assembled with Gold Nanoparticles/Nafion/Multi-wall Carbon Nanotube / 中国实验方剂学杂志

Objective::A new-type electrochemical sensor was developed by electrodepositing gold nanoparticle on the surface of glassy carbon electrode (GCE) modified by Nafion-multi-wall carbon nanotube (MWNTs) by the potentiostatic method, and used for the detection of rutin in practical samples. Method::The electrochemical properties of the sensor in potassium ferricyanide-potassium ferrocyanide system were studied by electrochemical impedance spectroscopy and cyclic voltammetric method, in order to explore the electrochemical performance of the sensor. The electrochemical behavior of rutin on the surface of the sensor was studied by the cyclic voltammetric method, and the factors affecting the performance of the sensor were optimized. The content of rutin was determined by differential pulse voltammetric methods. Result::The optimized conditions were -0.25 V of the deposition potential of gold nanoparticle, 20 s of the deposition time, pH 3.0, and 6 μL of 1 g·L-1 carbon nanotube. Under the conditions, a good linear relationship between reduction peak current and rutin concentration was obtained from 5.0 ×10-9 to 7.0 ×10-7 mol·L-1, and the detection limit was 3.6×10-9 mol·L-1. Conclusion::The developed sensor has a good electrical conductivity and stability, and is highly sensitive and simple for the detection of rutin, with a low detection limit. It has been successfully applied to the detection of rutin in Sophorae Immaturus Flos with the recoveries between 97.6%and 104.4%, which provides a new method for the determination of rutin and a new idea for the quality control of Chinese medicinal materials.

Biological behaviors of fibroblasts on the surface of TiO2 nanotubes with different diameters after annealing treatment / 中国组织工程研究

BACKGROUND: Previous studies have shown that titanium nanotubes with different diameters affect the adhesion and growth of cells on the implant surface. OBJECTIVE: To investigate the effects of annealing treatment on the biological behaviors of fibroblasts on the surface of TiO2 nanotubes with different diameters. METHODS: TiO2 nanotubes were prepared by polishing pure titanium samples through anodizing at 5 V and 20 V respectively, and then annealed. The pure titanium samples were divided into six groups: P (polishing titanium), NT5 (TiO2 nanotubes prepared at 5 V), NT20 (TiO2 nanotubes prepared at 20 V), A-P (annealing treatment and polishing titanium), A-NT5 (TiO2 nanotubes prepared at 5V and annealed) and A-NT20 (TiO2 nanotubes formed at 20 V and annealed). Field emission scanning electron microscopy was used to obsesrve the surface topography. Fibroblasts were inoculated on the surface of each group of samples. After 60 and 120 minutes of culture, the number of cells adhering to titanium sample surface was counted using cell nucleus staining method. On day 1 of culture, cell morphology was observed using scanning electron microscopy. On days 1, 3 and 5 of culture, cell proliferation was detected by MTT method. On day 3 of culture, the secretion of collagen fiber was detected by picro-sirius red staining method. RESULTS AND CONCLUSION: (1) The annealing treatment had no significant effect on the morphology and diameter of the nanotubes. (2) The number of adherent cells in the NT5 and NT20 groups was significantly lower than that in the P group. The annealing treatment increased the number of fibroblasts on the surface of polished pure titanium and decreased the number of fibroblasts in the NT5 and NT20 groups. (3) Annealing enhanced the viability of fibroblasts on the surface of polished pure titanium and decreased the viability of cells on the surface of nanotubes prepared at 5 and 20 V. (4) Cell viability in the NT5 and NT20 groups was lower than that in the P group. Annealing treatment increased the viability of cells on the surface of polished pure titanium and decreased the viability of cells on the surface of nanotubes prepared at 5 and 20 V. (5) The level of collagen on the surface of nanotubes in the NT5 and NT20 groups was higher than that in the P group. Annealing treatment increased the level of collagen on the surface of polished pure titanium and decreased the level of collagen in the NT5 and NT20 groups. These findings suggest that TiO2 nanotubes inhibit the adhesion, spreading and proliferation of fibroblasts to different degrees; annealing treatment can enhance this inhibitory effect; TiO2 nanotubes enhance collagen secretion by fibroblasts to different degrees, and annealing treatment inhibits the enhancement.

TGA/Chemometrics addressing innovative preparation strategies for functionalized carbon nanotubes / 药物分析学报

In this work, functionalized carbon nanotubes (CNTs) using two polyamine polymers, polyethyleneimine (PEI) and polyamidoamine dendrimer (PAMAM), were investigated by thermal analysis in order to address preparation strategies to obtain low cytotoxic compounds with the ability to conjugate micro-RNAs and, at the same time, to transfect efficiently endothelial cells. Thermogravimetric analysis (TGA) was coupled to chemometrics as a novel analytical strategy to characterize functionalized CNTs from different preparation conditions. In particular, two starting materials were considered:very small CNTs and carboxylated CNTs (CNT-COOH) in order to examine the affinity with polymers. Chemometrics permitted to compare results from TGA and to investigate the effect of a number of factors affecting the synthesis of coated nanotubes including a different amount of involved polymer and the time required for the suspension for a satisfactory and reproducible preparation procedure. The results demonstrated the effectiveness of TGA as a tool able to address synthesis of coated CNTs to be employed as efficient drug delivery vectors in biomedical applications.

Application progress of carbon nanotube-based targeted ultrasound contrast agent in tumors / 中国介入影像与治疗学

Nano-targeted ultrasound contrast agents have many advantages, such as no radiation, small side effects, real-time imaging and high targeting, etc. Among them carbon nanotube (CNT) has unique optical, electrical and acoustic properties, as well as high specific surface area and good biocompatibility. By embellishing or modifying CNT, excellent properties can be prepared and used in diagnosis and treatment of tumors. The application progress of CNT-based targeted ultrasound contrast agents in tumors were reviewed in this article.