Effects of titanium dioxide nanoparticles on circRNA expression profiles in human hepatocellular carcinoma cells HepG2 / 北京大学学报(医学版)

OBJECTIVE@#To investigate the effect of titanium dioxide nanoparticles (TiO2 NPs) on the expression profile of circular ribonucleic acid (circRNA) in human hepatocytes through in vitro cell experiments, and to attempt to understand the potential mechanism of hepatotoxicity through bioinformatics analysis.@*METHODS@#TiO2 NPs were characterized from the aspects of particle size, shape and agglomeration state. The cell counting kit-8 (CCK8) was used to detect the cytotoxicity of TiO2 NPs against human hepatocellular carcinoma cells (HepG2) after exposure to 0, 1.56, 3.13, 6.25, 12.5, 25, 50, 100, and 200 mg/L TiO2 NPs for 24 h or 48 h. The cells were treated at doses of 0 mg/L TiO2 NPs (control group) and 100 mg/L TiO2 NPs (treatment group), and collected after exposure for 48 h, and then RNA from the extracted cell samples was collected and sequenced. The differential circRNAs between the control and the TiO2 NPs treatment groups were screened, and then the enrichment pathway of the differential circRNA target gene was analyzed by multivariate statistics. According to the sequencing results, significantly altered genes and important genes in the significant enrichment pathways were screened, and real-time reverse transcription-polymerase chain reaction (real-time RT-PCR) was performed to verify the results.@*RESULTS@#TiO2 NPs were spherical anatase with a hydrated particle size of (323.50±85.44) nm and a Zeta potential of (-21.00±0.72) mV in a serum-free medium. The results of the CCK8 cytotoxicity assay showed that with the increase of TiO2 NPs concentration, cell viability gradually decreased. A total of 11 478 circRNAs were found by RNA sequencing. Compared with the control groups, TiO2 NPs treatment groups (100 mg/L) had a total of 89 differential circRNAs, of which 59 were up-regulated and 30 were down-regulated. Analysis of the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway showed that the targeted genes of differential circRNAs were mainly enriched in fatty acid degradation, Fanconi anemia pathway, and fatty acid metabolism. The expression levels of circRNA.6730, circRNA.3650 and circRNA.4321 were significantly different between the TiO2 NPs treatment group and the control group, which were consistent with the sequencing results.@*CONCLUSION@#TiO2 NPs can induce changes in circRNA expression profile, and epigenetics may play an important role in the mechanism of hepatotoxicity.

Anti-Bacterial Effect, Fluoride Release, and Compressive Strength of a Glass ionomer Containing Silver and Titanium Nanoparticles

Background: Many attempts have been made to enhance the anti?cariogenic properties of the conventional glass ionomer through incorporation of variable materials. However, most importantly, the incorporation of such materials should not jeopardise the physical or mechanical properties of the final restoration. Aims: To investigate the effect of adding silver nanoparticles (Ag?NPs) and titanium dioxide nanoparticles (TiO2?NPs) to conventional glass ionomer cement (GIC) on its anti?bacterial effect against Streptococcus mutans (S. mutans), fluoride ion release, and compressive strength (CS). Settings and Design: This study was an in vitro investigation where 30?disc specimens were prepared in each of the three studied groups. Materials and Methods: The specimens were categorized into the control group (Group C), in which conventional GIC was used, and Group Ag and Group Ti, in which 5 wt% of Ag?NP and TiO2?NP were added, respectively, to GIC powder. In each group, the anti?bacterial effect against S. mutans, fluoride ion release at 24 hours and 14 and 28 days, and CS were assessed. Data were analysed using one?way analysis of variance, followed by Tukey honest significant difference post?hoc test. Results: Both Ag and Ti groups showed a significantly higher anti?bacterial effect than the control group. Ag?NP increased fluoride ion release, whereas TiO2?NP decreased fluoride release; however, cumulative ion release of both experimental groups did not differ significantly compared to the control group. Adding Ag?NP and TiO2?NP increased CS, yet only the Ti group showed the highest CS mean value that was statistically significant compared to other groups. Conclusions: Adding 5 wt% TiO2?NP or Ag?NP to conventional GIC significantly increased its anti?bacterial effect and its CS without affecting fluoride release.

TiO2 nanoparticles and salinity stress in relation to artemisinin production and ADS and DBR2 expression in Artemisia absinthium L / Nanopartículas de TiO2 e estresse de salinidade em relação à produção de artemisinina e expressão de ADS e DBR2 em Artemisia absinthium L

Artemisia absinthium L. is an important herb that is widely cultivated in different parts of the world for its medicinal properties. The present study evaluated the effects of four concentrations of nanoparticles treatment (0, 10, 20 and 30 mg L-1) and NaCl salinity stress (0, 50, 100 and 150 mM NaCl) and their interactions with respect to the expression of two key genes, i.e. DBR2 and ADS, in the biosynthesis pathway of artemisinin in A. absinthium. Total RNA was extracted and a relative gene expression analysis was carried out using Real-Time PCR. The amount of artemisinin was also determined by HPLC. All the experiments were performed as factorial in a completely randomized design in three replications. The results revealed that salinity stress and nanoparticles treatment and their interaction affected the expressions of these genes significantly. The highest levels of ADS gene expression were observed in the 30 mg L-1 nanoparticles­treated plants in the presence of 150 mM salinity stress and the lowest levels in the 10 mg L-1 nanoparticles­treated plants under 50 mM salinity stress. The maximum DBR2 gene expression was recorded in the 10 mg L-1 nanoparticles­treated plants in the absence of salinity stress and the minimum expression in the 100 mM salinity-stressed plants in the absence of nanoparticles treatment. Moreover, the smallest amounts of artemisinin were observed in the 150 mM salinity-stressed plants in the absence of nanoparticles and the highest amounts in the 30 mg L-1 nanoparticles­treated plants. The maximum amounts of artemisinin and ADS gene expression were reported from the plants in the same nanoparticles treatment and salinity stress conditions. In this regard, the amount of artemisinin was decreased by half in the plants containing the highest DBR2 gene expression. Meanwhile, no significant correlation was observed between these gene expressions and the artemisinin amount in the other nanoparticles­treated plants under different levels of salinity stress. The biosynthetic pathway of secondary metabolites appears to be very complex and dose not directly dependent on these gene expressions.

Artemisia absinthium L. é uma erva importante que é amplamente cultivada em diferentes partes do mundo por suas propriedades medicinais. O presente estudo avaliou os efeitos de quatro concentrações de tratamento com nanopartículas (0, 10, 20 e 30 mg L-1) e estresse de salinidade com NaCl (0, 50, 100 e 150 mM NaCl) e suas interações com relação à expressão de dois genes-chave, isto é, DBR2 e ADS, na via de biossíntese da artemisinina em A. absinthium. O RNA total foi extraído, e uma análise de expressão gênica relativa foi realizada usando PCR em tempo real. A quantidade de artemisinina também foi determinada por HPLC. Todos os experimentos foram realizados como fatorial, em delineamento inteiramente casualizado, em três repetições. Os resultados revelaram que o estresse por salinidade e o tratamento com nanopartículas e sua interação afetaram significativamente as expressões desses genes. Os níveis mais altos de expressão do gene ADS foram observados nas plantas tratadas com nanopartículas de 30 mg L-1 na presença de estresse de salinidade de 150 mM, e os níveis mais baixos, nas plantas tratadas com nanopartículas de 10 mg L-1 com estresse de salinidade de 50 mM. A expressão máxima do gene DBR2 foi registrada nas plantas tratadas com nanopartículas de 10 mg L-1 na ausência de estresse de salinidade, e a expressão mínima, nas plantas estressadas com salinidade de 100 mM na ausência de tratamento com nanopartículas. Além disso, as menores quantidades de artemisinina foram observadas nas plantas com estresse de salinidade de 150 mM na ausência de nanopartículas, e as maiores quantidades, nas plantas tratadas com nanopartículas de 30 mg L-1. As quantidades máximas de expressão de genes de artemisinina e ADS foram relatadas a partir das plantas no mesmo tratamento com nanopartículas e condições de estresse de salinidade. A esse respeito, a quantidade de artemisinina diminuiu pela metade nas plantas que contêm a expressão gênica DBR2 mais alta. Enquanto isso, nenhuma correlação significativa foi observada entre essas expressões gênicas e a quantidade de artemisinina nas outras plantas tratadas com nanopartículas sob diferentes níveis de estresse de salinidade. A via biossintética dos metabólitos secundários parece ser muito complexa e não depende diretamente dessas expressões gênicas.

TiO2 nanoparticles and salinity stress in relation to artemisinin production and ADS and DBR2 expression in Artemisia absinthium L / Nanopartículas de TiO2 e estresse de salinidade em relação à produção de artemisinina e expressão de ADS e DBR2 em Artemisia absinthium L

Artemisia absinthium L. is an important herb that is widely cultivated in different parts of the world for its medicinal properties. The present study evaluated the effects of four concentrations of nanoparticles treatment (0, 10, 20 and 30 mg L-¹) and NaCl salinity stress (0, 50, 100 and 150 mM NaCl) and their interactions with respect to the expression of two key genes, i.e. DBR2 and ADS, in the biosynthesis pathway of artemisinin in A. absinthium. Total RNA was extracted and a relative gene expression analysis was carried out using Real-Time PCR. The amount of artemisinin was also determined by HPLC. All the experiments were performed as factorial in a completely randomized design in three replications. The results revealed that salinity stress and nanoparticles treatment and their interaction affected the expressions of these genes significantly. The highest levels of ADS gene expression were observed in the 30 mg L-¹ nanoparticles–treated plants in the presence of 150 mM salinity stress and the lowest levels in the 10 mg L-¹ nanoparticles–treated plants under 50 mM salinity stress. The maximum DBR2 gene expression was recorded in the 10 mg L-¹ nanoparticles–treated plants in the absence of salinity stress and the minimum expression in the 100 mM salinity-stressed plants in the absence of nanoparticles treatment. Moreover, the smallest amounts of artemisinin were observed in the 150 mM salinity-stressed plants in the absence of nanoparticles and the highest amounts in the 30 mg L-¹ nanoparticles–treated plants. The maximum amounts of artemisinin and ADS gene expression were reported from the plants in the same nanoparticles treatment and salinity stress [...].

Artemisia absinthium L. é uma erva importante que é amplamente cultivada em diferentes partes do mundo por suas propriedades medicinais. O presente estudo avaliou os efeitos de quatro concentrações de tratamento com nanopartículas (0, 10, 20 e 30 mg L-¹) e estresse de salinidade com NaCl (0, 50, 100 e 150 mM NaCl) e suas interações com relação à expressão de dois genes-chave, isto é, DBR2 e ADS, na via de biossíntese da artemisinina em A. absinthium. O RNA total foi extraído, e uma análise de expressão gênica relativa foi realizada usando PCR em tempo real. A quantidade de artemisinina também foi determinada por HPLC. Todos os experimentos foram realizados como fatorial, em delineamento inteiramente casualizado, em três repetições. Os resultados revelaram que o estresse por salinidade e o tratamento com nanopartículas e sua interação afetaram significativamente as expressões desses genes. Os níveis mais altos de expressão do gene ADS foram observados nas plantas tratadas com nanopartículas de 30 mg L-¹ na presença de estresse de salinidade de 150 mM, e os níveis mais baixos, nas plantas tratadas com nanopartículas de 10 mg L-¹ com estresse de salinidade de 50 mM. A expressão máxima do gene DBR2 foi registrada nas plantas tratadas com nanopartículas de 10 mg L-¹ na ausência de estresse de salinidade, e a expressão mínima, nas plantas estressadas com salinidade de 100 mM na ausência de tratamento com nanopartículas. Além disso, as menores quantidades de artemisinina foram observadas nas plantas com estresse de salinidade de 150 mM na ausência de nanopartículas, e as maiores quantidades, nas plantas tratadas com nanopartículas de 30 mg L-¹. As quantidades máximas de expressão de genes de artemisinina e ADS foram relatadas a partir das plantas no mesmo tratamento com nanopartículas e condições de estresse de salinidade. A esse respeito, a quantidade de artemisinina diminuiu pela metade nas [...],

TiO2 nanoparticles and salinity stress in relation to artemisinin production and ADS and DBR2 expression in Artemisia absinthium L

Abstract Artemisia absinthium L. is an important herb that is widely cultivated in different parts of the world for its medicinal properties. The present study evaluated the effects of four concentrations of nanoparticles treatment (0, 10, 20 and 30 mg L-1) and NaCl salinity stress (0, 50, 100 and 150 mM NaCl) and their interactions with respect to the expression of two key genes, i.e. DBR2 and ADS, in the biosynthesis pathway of artemisinin in A. absinthium. Total RNA was extracted and a relative gene expression analysis was carried out using Real-Time PCR. The amount of artemisinin was also determined by HPLC. All the experiments were performed as factorial in a completely randomized design in three replications. The results revealed that salinity stress and nanoparticles treatment and their interaction affected the expressions of these genes significantly. The highest levels of ADS gene expression were observed in the 30 mg L-1 nanoparticlestreated plants in the presence of 150 mM salinity stress and the lowest levels in the 10 mg L-1 nanoparticlestreated plants under 50 mM salinity stress. The maximum DBR2 gene expression was recorded in the 10 mg L-1 nanoparticlestreated plants in the absence of salinity stress and the minimum expression in the 100 mM salinity-stressed plants in the absence of nanoparticles treatment. Moreover, the smallest amounts of artemisinin were observed in the 150 mM salinity-stressed plants in the absence of nanoparticles and the highest amounts in the 30 mg L-1 nanoparticlestreated plants. The maximum amounts of artemisinin and ADS gene expression were reported from the plants in the same nanoparticles treatment and salinity stress conditions. In this regard, the amount of artemisinin was decreased by half in the plants containing the highest DBR2 gene expression. Meanwhile, no significant correlation was observed between these gene expressions and the artemisinin amount in the other nanoparticlestreated plants under different levels of salinity stress. The biosynthetic pathway of secondary metabolites appears to be very complex and dose not directly dependent on these gene expressions.

Resumo Artemisia absinthium L. é uma erva importante que é amplamente cultivada em diferentes partes do mundo por suas propriedades medicinais. O presente estudo avaliou os efeitos de quatro concentrações de tratamento com nanopartículas (0, 10, 20 e 30 mg L-1) e estresse de salinidade com NaCl (0, 50, 100 e 150 mM NaCl) e suas interações com relação à expressão de dois genes-chave, isto é, DBR2 e ADS, na via de biossíntese da artemisinina em A. absinthium. O RNA total foi extraído, e uma análise de expressão gênica relativa foi realizada usando PCR em tempo real. A quantidade de artemisinina também foi determinada por HPLC. Todos os experimentos foram realizados como fatorial, em delineamento inteiramente casualizado, em três repetições. Os resultados revelaram que o estresse por salinidade e o tratamento com nanopartículas e sua interação afetaram significativamente as expressões desses genes. Os níveis mais altos de expressão do gene ADS foram observados nas plantas tratadas com nanopartículas de 30 mg L-1 na presença de estresse de salinidade de 150 mM, e os níveis mais baixos, nas plantas tratadas com nanopartículas de 10 mg L-1 com estresse de salinidade de 50 mM. A expressão máxima do gene DBR2 foi registrada nas plantas tratadas com nanopartículas de 10 mg L-1 na ausência de estresse de salinidade, e a expressão mínima, nas plantas estressadas com salinidade de 100 mM na ausência de tratamento com nanopartículas. Além disso, as menores quantidades de artemisinina foram observadas nas plantas com estresse de salinidade de 150 mM na ausência de nanopartículas, e as maiores quantidades, nas plantas tratadas com nanopartículas de 30 mg L-1. As quantidades máximas de expressão de genes de artemisinina e ADS foram relatadas a partir das plantas no mesmo tratamento com nanopartículas e condições de estresse de salinidade. A esse respeito, a quantidade de artemisinina diminuiu pela metade nas plantas que contêm a expressão gênica DBR2 mais alta. Enquanto isso, nenhuma correlação significativa foi observada entre essas expressões gênicas e a quantidade de artemisinina nas outras plantas tratadas com nanopartículas sob diferentes níveis de estresse de salinidade. A via biossintética dos metabólitos secundários parece ser muito complexa e não depende diretamente dessas expressões gênicas.

Killing effects in vitro of a new photosensitizer black titanium dioxide-mediated photodynamics on prostate cancer cells / 肿瘤研究与临床

Objective:To investigate the killing effects in vitro of a new photosensitizer black titanium dioxide b-TP-700-mediated photodynamics on prostate cancer cell line PC-3 cells.Methods:The b-TP-700 was successfully prepared by using solid phase in situ thermal reduction method. PC-3 cells were treated with 31.25, 62.5, 125, 250, 500, 1 000 μg/ml b-TP-700 for 12, 24, 48 h. The cell activity was detected by using CCK-8 method, and the morphology of PC-3 cells was observed by using confocal fluorescence microscope, the toxicity of b-TP-700 to PC-3 cells was also judged. PC-3 cells were treated with different concentrations of b-TP-700 (31.25, 62.5, 125, 250, 500 μg/ml) and irradiated with laser (1 W/cm, 808 nm) for 1, 3, 5, 7 min. The cell activity was detected by using CCK-8 method. The production of reactive oxygen species in PC-3 cells cultured in 250 μg/ml b-TP-700 after laser irradiation for 5 min was detected by using confocal fluorescence microscopy. The non-laser irradiation cells were selected as the control group.Results:There were no statistically significant differences in cell activity of PC-3 cells treated with different concentrations of b-TP-700 for the same time ( F value was 1.26, 0.39 and 0.37, respectively; all P > 0.05). PC-3 cells were treated with 1 000 μg/ml b-TP-700 for 24 h, no obvious morphological changes and no obvious dead cells were observed under fluorescence microscope. When PC-3 cells were treated with the same concentration of b-TP-700, the activity of PC-3 cells was decreased with the extension of laser excitation time. Under the same laser excitation time, the activity of PC-3 cells was decreased with the increase of b-TP-700 concentration (all P < 0.05). Under laser irradiation, obvious green fluorescence could be detected in the PC-3 cells treated with 250 μg/ml b-TP-700, while almost no green fluorescence could be observed in the control group. Conclusions:A new photosensitizer b-TP-700 has the good reactive oxygen generation ability. b-TP-700-mediated photodynamics show obvious killing effects on prostate cancer PC-3 cells in vitro, which is expected to be a new method for the treatment of prostate cancer.

Effects of nano titanium dioxide on gut microbiota based on human digestive tract microecology simulation system in vitro / 北京大学学报(医学版)

OBJECTIVE@#To explore the effects of oral exposure to titanium dioxide nanoparticles (TiO2 NPs) on the composition and structure of human gut microbiota.@*METHODS@#The particle size, shape, crystal shape and degree of agglomeration in ultrapure water of TiO2 NPs were characterized. The in vitro human digestive tract microecological simulation system was established by simulating the fluid environment and physical conditions of stomach, small intestine and colon, and the stability of the simulation system was evaluated. The bacterial communities were extracted from human feces and cultured stably in the simulated system. They were exposed to 0, 20, 100 and 500 mg/L TiO2 NPs, respectively, and the bacterial fluids were collected after 24 h of exposure. The effect of TiO2 NPs on the composition and structure of human gut microbiota was analyzed by 16S rRNA sequencing technology. Linear discriminant analysis effect size (LEfSe) was used to screen differential bacteria, and the Kyoto encyclopedia of genes and genomes (KEGG) database for functional prediction.@*RESULTS@#The spherical and anatase TiO2 NPs were (25.12±5.64) nm in particle size, while in ultra-pure water hydrated particle size was (609.43±60.35) nm and Zeta potential was (-8.33±0.22) mV. The in vitro digestive tract microecology simulation system reached a relatively stable state after 24 hours, and the counts of Enterococci, Enterobacte-rium, and Lactobacillus reached (1.6±0.85)×107, (5.6±0.82)×107 and (2.7±1.32)×107, respectively. 16S rRNA sequencing results showed that compared with the control group, the number and evenness of gut microbiota were not significantly affected at phylum, class, order, family and genus levels in TiO2 NPs groups (20, 100 and 500 mg/L). The relative abundance of some species was significantly changed, and a total of 42 different bacteria were screened between the TiO2 NPs groups (20, 100 and 500 mg/L) and the control group [linear discriminant analysis(LDA) score>3], represented by Enterobacter, Bacteroidaceae, Lactobacillaceae, Bifidobacteriaceae and Clostridium. Further predictive analysis of gut microbiota function showed that TiO2 NPs might affect oxidative phosphorylation, energy meta-bolism, phosphonate and phosphonate metabolism, and methane metabolism (P < 0.05).@*CONCLUSION@#In human digestive tract microecological simulation system, TiO2 NPs could significantly change the composition and structure of human gut microbiota, represented by Enterobacter and probiotics, and may further affect a variety of metabolism and function of the body.

Construction and immobilization of recombinant Bacillus subtilis with D-allulose 3-epimerase / 生物工程学报

D-allulose-3-epimerase (DPEase) is the key enzyme for isomerization of D-fructose to D-allulose. In order to improve its thermal stability, short amphiphilic peptides (SAP) were fused to the N-terminal of DPEase. SDS-PAGE analysis showed that the heterologously expressed DPEase folded correctly in Bacillus subtilis, and the protein size was 33 kDa. After incubation at 40 °C for 48 h, the residual enzyme activity of SAP1-DSDPEase was 58%. To make the recombinant B. subtilis strain reusable, cells were immobilized with a composite carrier of sodium alginate (SA) and titanium dioxide (TiO2). The results showed that 2% SA, 2% CaCl2, 0.03% glutaraldehyde solution and a ratio of TiO2 to SA of 1:4 were optimal for immobilization. Under these conditions, up to 82% of the activity of immobilized cells could be retained. Compared with free cells, the optimal reaction temperature of immobilized cells remained unchanged at 80 °C but the thermal stability improved. After 10 consecutive cycles, the mechanical strength remained unchanged, while 58% of the enzyme activity could be retained, with a conversion rate of 28.8% achieved. This study demonstrated a simple approach for using SAPs to improve the thermal stability of recombinant enzymes. Moreover, addition of TiO2 into SA during immobilization was demonstrated to increase the mechanical strength and reduce cell leakage.

Material cimentício fotocatalítico com atividade antimicrobiana: avanços e desafios no ambiente da área da saúde / Photocatalytic cement material with antimicrobial activity: advances and challenges in the healthcare environment

O material cimentício com dióxido de titânio (TiO2) pode representar uma opção viável devido suas propriedades fotocatalítica, autolimpante e antimicrobiana no ambiente da área da saúde. O objetivo desta pesquisa foi determinar os avanços e desafios da atividade antimicrobiana do material cimentício fotocatalítico com TiO2, no que concerne a possível aplicabilidade no ambiente da área da saúde. Uma revisão integrativa foi efetuada acerca da possível aplicabilidade do material cimentício fotocatalítico com TiO2 no ambiente da área da saúde. Além disso, a atividade antibacteriana de soluções aquosas e material cimentício fotocatalítico com TiO2 em diferentes concentrações e exposições a radiações luminosas foram avaliadas, por meio da técnica de difusão em camada dupla de ágar. A revisão integrativa foi realizada no portal PubMed e nas bases Web of Science, SCOPUS, EMBASE e Engineering Village com a inclusão de estudos primários quanto a temática, publicados online até março de 2021, em português e inglês. A etapa experimental / laboratorial foi realizada em triplicata com o emprego da cepa padrão Escherichia coli (ATCC 25922) e as soluções aquosas e material cimentício fotocatalítico com TiO2 em diferentes concentrações (0, 5 e 15%) e exposições às radiações ultravioleta A (UV-A) a 15W e 365nm e diodo emissor de luz (LED) a 18W durante 8 e 10h. Cabe salientar que houve a inclusão de solução de clorexidina a 0,12% e amostras submetidas à ausência de exposição à radiação luminosa (escuro) como controles experimentais. Na técnica de difusão em camada dupla de ágar, Mueller Hinton Agar foi distribuído em placas de Petri (90x15mm) esterilizadas formando uma camada base de 12,0mL. Após a solidificação do meio de cultura, 8,0mL de Mueller Hinton Agar contendo 106UFC/mL do inóculo bacteriano foi distribuído sobre a camada base para formar a camada seed. Em seguida, em cada placa foram confeccionados poços para adição de 20,0µL das soluções ou dos espécimes do material cimentício fotocatalítico. Decorrido os períodos pré-incubação das amostras à temperatura ambiente por 2h, as placas foram incubadas a 37ºC por 24h e a leitura dos diâmetros dos halos de inibição (mm) mensurada. Na revisão integrativa, os resultados mostraram um total de sete estudos primários com diferentes metodologias microbiológicas in vitro, concentrações e exposições a radiações luminosas de soluções e materiais cimentícios fotocatalíticos. Em referência à etapa experimental / laboratorial, não houve atividade antibacteriana conclusiva de qualquer solução ou material cimentício fotocatalítico com TiO2, apesar de alguns resultados terem demonstrado halos de inibição tênues ao redor de algumas amostras do material cimentício fotocatalítico. Em conclusão, não há consenso na literatura científica acerca da atividade antimicrobiana de material cimentício fotocatalítico com TiO2. Ainda, conforme a metodologia empregada neste estudo, a atividade contra E. coli das soluções aquosas e do material cimentício fotocatalítico com TiO2 não foi evidenciada, sendo que avanços e desafios no controle de contaminação e risco de infecção microbiana no ambiente da área da saúde continuam

The cementitious material with titanium dioxide (TiO2) may represent a viable option due to its photocatalytic, self-cleaning and antimicrobial properties in the healthcare environment. The objective of this research was to determine the advances and challenges of the antimicrobial activity of the photocatalytic cement material with TiO2, with regard to the possible applicability in the health area. An integrative review was carried out on the possible applicability of the photocatalytic cement material with TiO2 in the healthcare environment. In addition, the antibacterial activity of aqueous solutions and photocatalytic cementitious material with TiO2 in different concentrations and exposures to light radiation were evaluated using the double layer agar diffusion technique. The integrative review was carried out on the PubMed portal and on the Web of Science, SCOPUS, EMBASE and Engineering Village databases with the inclusion of primary studies on the subject, published online until March 2021, in Portuguese and English. The experimental / laboratory stage was carried out in triplicate using the standard strain Escherichia coli (ATCC 25922) and aqueous solutions and photocatalytic cement material with TiO2 in different concentrations (0, 5 and 15%) and radiation exposures to ultraviolet A (UV-A) at 15W and 365nm and light emitting diode (LED) at 18W for 8 and 10am. It should be noted that there was the inclusion of 0.12% chlorhexidine solution and samples subjected to the absence of exposure to light radiation (dark) as experimental controls. In the double agar diffusion technique, Mueller Hinton Agar was distributed in sterile Petri dishes (90x15mm) forming a base layer of 12.0mL. After solidification of the culture medium, 8.0mL of Mueller Hinton Agar containing 106CFU/mL of the bacterial inoculum was distributed onto the base layer to form the seed layer. Then, in each plate, wells were made to add 20.0µL of the solutions or specimens of the photocatalytic cement material. After the pre-incubation periods of the samples at room temperature for 2h, the plates were incubated at 37ºC for 24h and the reading of the diameter of the inhibition halos (mm) was measured. In the integrative review, the results showed a total of seven primary studies with different in vitro microbiological methodologies, concentrations, and exposures to light radiation of solutions and photocatalytic cement materials. In reference to the experimental / laboratory stage, there was no conclusive antibacterial activity of any solution or photocatalytic cement material with TiO2, although some results have shown faint inhibition halos around some samples of the photocatalytic cement material. In conclusion, there is no consensus in the scientific literature about the antimicrobial activity of photocatalytic cement material with TiO2. Moreover, according to the methodology used in this study, the activity against E. coli from aqueous solutions and the photocatalytic cement material with TiO2 was not evidenced, and advances and challenges in the contamination control and microbial infection risk in the health area continue

Drug-release characteristic and biological toxicity of TiO2 nanotube/hydroxyapatite loaded vancomycin coating / 中国组织工程研究

BACKGROUND: In the scheme of titanium surface modification and coating modification, the drug sustained-release system constructed by surface nanotube modification and hydroxyapatite coating modification has broad clinical application prospects. OBJECTIVE: To construct composite drug loading coating of titanium dioxide nanotube/hydroxyapatite loaded with vancomycin hydrochloride, and analyze the drug release performance and cytotoxicity of the composite coating in vitro. METHODS: A two-step anodic oxidation method was used to construct titanium dioxide nanotubes on the titanium surface, and the prepared hydroxyapatite was loaded on the surface of the nanotubes by electrophoretic deposition, so as to obtain a nanotube/hydroxyapatite composite coating structure. Subsequently, the composite coating was used as a drug-loaded platform, and vancomycin hydrochloride was loaded by physical adsorption to finally obtain a composite drug-loaded coating. The in vitro drug release properties of hydroxyapatite/vancomycin hydrochloride, titanium dioxide nanotubes/vancomycin hydrochloride, titanium dioxide nanotubes/hydroxyapatite/vancomycin hydrochloride coating were measured. Human osteoblasts were cultured with titanium dioxide nanotubes/hydroxyapatite/vancomycin hydrochloride coating extracts of different concentrations. MTT assay was used to detect cytotoxicity. Human osteoblasts were inoculated on the surface of hydroxyapatite, titanium dioxide nanotubes, titanium dioxide nanotubes/hydroxyapatite/vancomycin hydrochloride, and the changes of cell morphology were observed. RESULTS AND CONCLUSION: (1) Compared with hydroxyapatite/vancomycin hydrochloride, titanium dioxide nanotube/vancomycin hydrochloride coating, titanium dioxide nanotube/hydroxyapatite/vancomycin hydrochloride coating had a longer drug sustained-release effect. The release time exceeded 150 hours. (2) The 10%, 50%, and 100% concentration of titanium dioxide nanotubes/hydroxyapatite/vancomycin hydrochloride coating extract had no obvious cytotoxicity. The relative activity of osteoblasts was more than 70%. (3) The osteoblasts on the three kinds of coating surface grow well; the cytoskeleton was intact; and the nucleus-cytoplasm ratio of the cells was normal, which was not significantly different from the morphology of the cells in pure culture. (4) The results show that the coating of titanium dioxide nanotubes/hydroxyapatite/vancomycin hydrochloride has good drug release properties in vitro without obvious cytotoxicity.

Screening serum biomarkers for occupational exposure to titanium dioxide nanoparticles using metabolomics / 中国职业医学

OBJECTIVE: To screen the serum biomarkers in workers occupationally exposed to titanium dioxide nanoparticles(TiO_2 NPs) using metabolomics technology. METHODS: Using a typical sampling method, 56 workers who have occupationally exposed to TiO_(2 )in a TiO_2 NPs manufacturer were selected as the exposure group and 44 employees without occupational exposure to TiO_2 were selected as the control group. The high performance liquid chromatography-mass spectrometry technology was used to perform non-targeted metabolomics detection. The difference in serum metabolite profiles of the TiO_2 NPs exposure group and the control group were analyzed. Key differential metabolites and potential biomarkers were screened. The sensitivity and specificity of biomarkers were assessed through receiver operating characteristic(ROC) curve.RESULTS: We detected a total of 1 492 mass spectrum peaks in serum samples by serum metabolomics analysis, and 413 well-matched metabolites were obtained after annotation and identification. The results of principal component analysis and orthogonal partial least squares discriminant analysis showed that a total of 296 differentially expressed metabolites were found in the serum of individuals of the exposure group compared with the control group(all P<0.01). Among them the relative expression of metabolites increased in 265 species and decreased in 31 species. The ROC analysis results showed that the area under the ROC curve of five metabolites exceeded 0.900, and these metabolites included tanacetol A,(5 E)-2-hydroxy-4-oxobenzopenta-5-en-1-ylacetic acid, triterpene saponins organic compounds, 9,10,13-trihydroxystearic acid, and liquoric acid. The multiple linear regression analysis showed that the relative expression of all the five metabolites were positively correlated with occupational exposure to TiO_2 NPs after adjusting for the influence of confounding factors such as gender, age, body mass index, smoking and drinking(all P<0.01). CONCLUSION: Occupational exposure to TiO_2 NPs could induce changes in serum metabolite profiles. The metabolites represented by tanacetol A in serum can be used as potential biomarkers for indicating occupational exposure to TiO_2 NPs.

Influence of oxidative/antioxidative biomarkers and inflammatory cytokines on rats after sub-acute orally administration of titanium dioxide nanoparticles / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the sub-acute oral effect of titanium dioxide (TiO2) nanoparticles on the oxidation/antioxidation biomarkers and inflammatory cytokines in blood, liver, intestine, and colon in rats.@*METHODS@#Twenty four 4-week-old clean-grade Sprague Dawley (SD) rats were randomly devided into 4 groups by body weight (n=6, control, low, middle, and high), in which the rats were orally exposed to TiO2 nanoparticles at doses of 0, 2, 10 and 50 mg/kg body weight/day for 28 consecutive days separately. Food intake, body weight and abnormal behaviors during the experiment were recorded. The rats were euthanized on the 29th day. The blood was collected via abdominal aortic method and centrifuged to collect the serum. Tissues from liver, intestine and colon were collected and homogenated. Then enzyme-linked immunosorbent assay (ELISA) and microwell plate methods were used to detect oxidation/antioxidation biomarkers including superoxide dismutase (SOD), glutathione (GSH), glutathione peroxidase (GSH-Px), total mercapto (T-SH), glutathione disulfide (GSSG), malomdialdehvde (MDA) and inflammatory cytokines including interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) in the serum, liver, intestine and colon in the rats.@*RESULTS@#Compared with the control group, no significant differences in body weight, food intake and organ coefficients were observed in all the three groups after TiO2 gavage. No significant changes in GSH, GSH-Px, T-SH, and IL-6 were observed. Compared with the control group, significant increase of SOD activity in serum in high dose group, signi-ficant increase of GSSG concentration in intestine in middle and high dose group and significant increase of MDA concentration in liver in low and high dose group were observed. Compared with the control group, a significant increase of TNF-α in liver in middle and high dose group was observed.@*CONCLUSION@#TiO2 nanoparticle can increase antioxidant enzymes activities in blood, increase oxidative biomarkers in liver and intestine, increase inflammatory cytokines in liver in rats after a 28-day sub-acute orally administration. Among blood, liver, intestine, and colon, liver is most sensitive to the toxicity induced by TiO2 nanoparticles, followed by intestine, blood, and colon in sequence.

Effects of titanium dioxide nanoparticles on fecal metabolome in rats after oral administration for 90 days / 北京大学学报(医学版)

OBJECTIVE@#To explore the effects and related mechanisms of oral exposure titanium dioxide nanoparticles (TiO2 NPs) for 90 days on the intestinal and the gut microbiota of rats, through fecal metabolomics.@*METHODS@#Twelve 4-week-old clean-grade Sprague Dawley (SD) rats were randomly de-vided into 2 groups by body weight, treated with TiO2 NPs at dose of 0 or 50 mg/kg body weight everyday respectively for 90 days. The solution of each infection was freshly prepared and shocked fully by ultrasonic. Characterization of the particle size, crystal form, purity, and specific surface area of TiO2 NPs was conducted. And the fresh feces of the rats were collected on the 90th day. After lyophilized and hydrophilic phase extraction, ultra performance liquid chromatography-Q-exactive orbitrap-high-resolution mass spectrometry system (UPLC-QEMS) was utilized for non-targeted determination of fecal meta-bolites. The metabolites were identified and labeled through Compound Discoverer 3.0 software, and used for subsequent metabolomics analysis. Bioinformatics analysis was carried out including unsupervised principal component analysis and supervised orthogonal projection to latent structure discriminant analysis for the differential metabolites between the two groups. The differential metabolites were followed-up for Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis.@*RESULTS@#Compared with the control group, the body weight of the rats was significantly reduced (P<0.05) in the treatment group. A total of 22 metabolites in fecal metabolomics showed significant changes. Among them, xanthine, 1-methyladenine, 3-hydroxypyridine, methionine sulfoxide, pyridoxine, 1,5-isoquinolinediol, N-acetylornithine, N-acetyl-D-galactosamine, L-citrulline, L-methionine, leucine, DL-tryptophan, L-ornithine, 4-methyl-5-thiazoleethanol, and L-glutamic acid totaled 15 metabolites increased significantly. N-acetylhistamine, D-pipecolinic acid, imidazolelactic acid, L-valine, 2,3,4,6-tetramethylpyrazine, caprolactam, and histamine totaled 7 metabolites decreased significantly. N-acetylhistamine, L-valine and methionine sulfoxide were changed more than 16 times. Analysis of KEGG pathway revealed that the two metabolic pathways arginine biosynthesis and aminoacyl-tRNA biosynthesis were significantly changed (false discover rate < 0.05, pathway impact > 0.1).@*CONCLUSION@#Oral exposure to TiO2 NPs for 90 days could disrupt the metabolism of the intestine and gut microbiota, causing significant changes in metabolites and metabolic pathways which were related to inflammatory response, oxidative stress, glucose homeostasis, blood system and amino acid homeostasis in rat feces. It is suggested that the toxic effect of TiO2 NPs on rats may be closely related to intestinal and gut microbiota metabolism.

Effect of subchronic combined oral exposure of titanium dioxide nanoparticles and glucose on levels of serum folate and vitamin B12 in young SD rats / 北京大学学报(医学版)

OBJECTIVE@#To explore the effect of subchronic combined oral exposure of titanium dioxide nanoparticles and glucose on levels of serum folate and vitamin B12 in young SD rats.@*METHODS@#At first, the physical and chemical properties of titanium dioxide nanoparticles, such as particle size, shape, crystal form and agglomeration degree in solution system, were characterized in detail. Eighty 4-week-old young SD rats were randomly divided into 8 groups (10 rats in each group, half male and half female). The rats were exposed to titanium dioxide nanoparticles through intragastric administration at 0, 2, 10 and 50 mg/kg body weight with or without 1.8 g/kg glucose daily for 90 days. At last, the concentrations of serum folate and vitamin B12 were detected.@*RESULTS@#Titanium dioxide nanoparticles were anatase crystals, closely spherical shape, with an average particle size of (24±5) nm. In male young rats, compared with the control group, the serum folate concentration was significantly increased when exposed to titanium dioxide nanoparticles (10 mg/kg) and glucose. The difference was statistically significant (P<0.05). However, in female and male young rats, compared with glucose (1.8 g/kg) exposure group, titanium dioxide nanoparticles (50 mg/kg) and glucose significantly reduced the serum folate concentration. The difference was statistically significant (P<0.05). Through statistical analysis of factorial design and calculation of interaction, obvious antagonistic effect was observed between titanium dioxide nanoparticles and glucose on the serum folate concentration in the young female SD rats. The combined oral exposure of titanium dioxide nanoparticles and glucose had little effect on the concentration of serum vitamin B12 in the young SD rats, with no significant interaction between the two substances. It was only found that titanium dioxide nanoparticles (2 mg/kg) and glucose significantly increased the serum vitamin B12 concentration, compared with glucose (1.8 g/kg) exposure group. The difference was statistically significant (P<0.05).@*CONCLUSION@#Subchronic combined oral exposure of titanium dioxide nanoparticles and glucose had an obvious antagonistic effect on serum folate concentrations in young SD rats.

Evaluation of the Transverse Strength of the Heat Cure PMMA Resin Reinforced with Various Concentrations of Two Different Nanoparticles: An In vitro Study

Purpose: The purpose of the study was to evaluate the effect of titanium dioxide and zirconia nanoparticles on transverse strength of heat cure PMMA resin routinely used for complete denture fabrication.Methods: One hundred samples of PMMA resin were made and divided into five groups (20 samples for each group). The test specimens were divided into five groups depending on the concentration of reinforcing nanoparticles as Group 1,2,3,4 and 5; Group 1: PMMA unreinforced (control group), Group 2: PMMA reinforced with 2.5% nanozirconia, Group 3: PMMA reinforced with 5% nanozirconia, Group 4: PMMA reinforced with 2.5% titanium dioxide nanoparticles, and Original ResearchArticle Group 5: PMMA reinforced with 5% titanium dioxide nanoparticles. Universal testing machine was used to conduct a three-point bending test and evaluate the transverse strength of samples. Comparison of mean transverse strength for various groups was carried out by employing one‑way analysis of variance and Bonferroni post hoc tests.Results:The highest and lowest mean transverse strength were observed in Group 3 and 1, respectively. Bonferroni post hoc test showed increase in transverse strength after reinforcement to be statistically significant between all the groups (P = .05) except between the samples of group G1 and G5 and G2 and G3.Conclusion: Addition of nanoparticles in all concentrations significantly increased transverse strength of heat cure PMMA resin as compared to control group. The best result was obtained after adding 5% of nanozirconia particles to the conventional heat polymerized acrylic resin

Preparation and characterization of rutile phase TiO₂ nanoparticles and their cytocompatibility with oral cancer cells

In the present study, rutile phase titanium dioxide nanoparticles (R-TiO₂ NPs) were prepared by hydrolysis of titanium tetrachloride in an aqueous solution followed by calcination at 900℃. The composition of R-TiO₂ NPs was determined by the analysis of X-ray diffraction data, and the characteristic features of R-TiO₂ NPs such as the surface functional group, particle size, shape, surface topography, and morphological behavior were analyzed by Fourier-transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy, transmission electron microscopy, dynamic light scattering, and zeta potential measurements. The average size of the prepared R-TiO₂ NPs was 76 nm, the surface area was 19 m²/g, zeta potential was −20.8 mV, and average hydrodynamic diameter in dimethyl sulfoxide (DMSO)–H₂O solution was 550 nm. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and morphological observations revealed that R-TiO₂ NPs were cytocompatible with oral cancer cells, with no inhibition of cell growth and proliferation. This suggests the efficacy of R-TiO₂ NPs for the aesthetic white pigmentation of teeth.

Preparation of Adriamycin Hydrochloride Magnetic Thermosensitive Liposome Based on TiO 2@Fe3O4 and Its Physicochemical Properties，Magnetic Effect and Photothermal Effect Study / 中国药房

OBJECTIVE： To prepare Adriamycin hydrochloride （DOX） magnetic thermosensitive liposome （MTSL）， investigate its physicochemical properties， magnetic effect and photothermal effect， so as to provide reference for tumor chemo- therapy and photodynamic/photothermal therapy. METHODS： Using DOX as model drug， TiO2@Fe3O4 as photosensitizers and magnetic materials， DOX-TiO2@Fe3O4-MTSL was prepared with membrane dispersion method. The morphology and dispersibility were observed； particle size and Zeta potential were detected； encapsulation efficiency of the liposome were determined by centrifugal ultrafiltration and HPLC. Its paramagnetism property was also detected by magnetometer. Compared with DOX solution， in vitro release behavior of the liposome was investigated by dialysis method， and the release curves at different temperatures （at 37， 43 ℃） were compared. The photothermal conversion effect of the liposome and the production of reactive oxygen species （ROS） in human breast cancer MCF-7 cells were investigated by near infrared laser irradiation at 808 nm. RESULTS： Prepared DOX-TiO2@Fe3O4-MTSL was brown-black with good water dispersion， and was spherical in shape and uniform in size under electron microscopy. Average particle size was 250.6 nm； polydispersity index was 0.107； Zeta potential was （－7.76±3.41）mV； encapsulation efficiency was （92.3±3.2）％. Under the external magnetic field， the liposome could move in a directional direction and had obvious paramagnetism. Compared with DOX solution， the liposomes released slowly and showed obvious sustained- release characteristics. Compared with at 37 ℃， the drug release of liposome speeded up significantly at 43 ℃.With the increase of laser （808 nm） irradiation time， the temperature of the liposome kept rising， which had obvious photothermal conversion effect and could induce the increase of ROS in MCF-7 cells. CONCLUSIONS： DOX-TiO2@Fe3O4-MTSL is prepared succe- ssfully， which has uniform appearance， good physical and chemical properties. It has obvious paramagnetism sustained release effect and photothermal conversion efficiency， and can promote ROS production in MCF-7 cells under near infrared laser irradiation at 808 nm.

Shear bond strength and adhesive remnant index of orthodontic brackets bonded to enamel using adhesive systems mixed with TiO2 nanoparticles

ABSTRACT Introduction: It is recently suggested that titanium dioxide (TiO2) nanoparticles can be added to bracket luting agents in order to reduce bacterial activity and protect the enamel. However, it is not known if this addition can affect the shear bond strength (SBS) below clinically acceptable levels. Therefore, this study examined this matter within a comprehensive setup. Methods: This in vitro experimental study was conducted on 120 extracted human premolars randomly divided into four groups (n=30): in groups 1 and 2, Transbond XT light-cured composite with or without TiO2 was applied on bracket base; in groups 3 and 4, Resilience light-cured composite with or without TiO2 was used. Brackets were bonded to teeth. Specimens in each group (n=30) were divided into three subgroups of 10 each; then incubated at 37°C for one day, one month, or three months. The SBS and adhesive remnant index (ARI) were calculated and compared statistically within groups. Results: The SBS was not significantly different at one day, one month or three months (p>0.05) but composites without TiO2 had a significantly higher mean SBS than composites containing TiO2 (p<0.001). The SBS of Transbond XT was significantly higher than that of Resilience (p<0.001). No significant differences were noted in ARI scores based on the type of composite or addition of TiO2 (p>0.05). Conclusions: Addition of TiO2 nanoparticles to Transbond XT decreased its SBS to the level of SBS of Resilience without TiO2; thus, TiO2 nanoparticles may be added to Transbond XT composite for use in the clinical setting.

RESUMO Introdução: recentemente, sugeriu-se que nanopartículas de dióxido de titânio (TiO2) poderiam ser adicionadas ao cimento adesivo para reduzir a atividade bacteriana e proteger o esmalte. Entretanto, não se sabe se esse acréscimo pode reduzir a resistência adesiva ao cisalhamento (RAC) a níveis inferiores aos clinicamente aceitáveis. Assim, o presente estudo examinou essa questão dentro de um contexto abrangente. Métodos: esse estudo experimental in vitro foi realizado em 120 pré-molares humanos, aleatoriamente divididos em quatro grupos (n=30). Nos grupos 1 e 2, o adesivo fotopolimerizável Transbond XT com e sem TiO2 foi aplicado na base do braquete. Nos grupos 3 e 4, utilizou-se o adesivo fotopolimerizável Resilience com e sem TiO2. Os braquetes foram colados aos dentes e as amostras de cada grupo (n=30) foram divididas em três subgrupos de dez amostras cada, as quais foram incubadas a 37°C por, respectivamente, um dia, um mês e três meses. A RAC e o índice de adesivo remanescente (IAR) foram calculados e estatisticamente comparados entre os grupos. Resultados: a RAC não apresentou diferença significativa após um dia, um mês ou três meses (p > 0,05), mas os adesivos sem TiO2 apresentaram uma RAC média significativamente mais elevada do que os adesivos que continham TiO2 (p< 0,001). A RAC do Transbond XT foi significativamente mais elevada do que a do Resilience (p< 0,001). Não foram observadas diferenças significativas nos IARs, seja para o tipo de adesivo ou para a adição de TiO2 (p> 0,05). Conclusões: a adição de nanopartículas de TiO2 ao Transbond XT reduziu sua RAC a níveis semelhantes aos da RAC do Resilience TiO2. Assim, as nanopartículas de TiO2 podem ser acrescentadas ao adesivo Transbond XT para a aplicação clínica.

Research progress in photocatalysis of titanium dioxide nanowire / 口腔疾病防治

@#Because nanoparticles have particular characteristics, such as small size and surface effects, nano-TiO2 is widely used in air purification, wastewater treatment and self-cleaning. In recent years, TiO2 photocatalysis has thoroughly explored as a new titanium implant surface treatment method. Photocatalytic performance is better for TiO2 nanowires than for nano-TiO2 particles. Hence, these nanowires have received widespread attention with regard for their more specific surface area and surface energy, improved charge carrier transport efficiency, and enhanced charge collection efficiency. Photon-generated carrier transport moves in a one dimensional straight path along a nanowire, and this could decrease photoelectron loss. In this paper, we summarized the principles underlying, factors that influence, and applications involving TiO2 nanowire photocatalysis. Additionally, we describe its method of preparation and toxicity.

Simultaneous Synthesis and Characterization of Biomass Multi-elements Self-doped Titanium Dioxide by Ultrasonic Irradiation / 分析化学

The biomass multi-elements self-doped TiO2was synthesized simultaneously by ultrasonic irradiation assisted sol-gel method, and characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction(XRD), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (UV-Vis-DRS), Fourier transform infrared (FT-IR) spectroscopy, and photoluminescence (PL). The characterization results showed that,multiple elements, C, N, P, Cl and K, were doped in the composite TiO2. Compared with pure TiO2,the band gap of the composite catalyst was narrowed by 0.21 eV, and possessed more surface hydroxyl radical and active sites, lower recombination rate of photo-generated carriers, higher crystallinity and higher specific surface area. The photocatalytic ability of the composite catalyst was studied,using methylene blue (MB) as target pollutant. The experimental results showed that, under visible light irradiation,the degradation efficiency of methylene blue was up to 98% after photocatalytic reaction for two hours by the composite catalyst.