Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 16 de 16
Filtrar
Mais filtros

Base de dados
País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
J Craniofac Surg ; 2024 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-39171899

RESUMO

OBJECTIVE: Acute pericoronitis (AP) is a prevalent cause of odontogenic toothache which can significantly impact brain function. Previous research has predominantly concentrated on localized brain activity. However, the synergistic changes between brain hemispheres induced by toothache and resulting abnormal functional connectivity across the brain have not been comprehensively studied. METHODS: A total of 34 patients with AP and 34 healthy individuals, matched for age, sex, and education were recruited for this study. All participants underwent resting-state functional magnetic resonance imaging (rs-MRI) scans. The voxel mirror homotopic connectivity (VMHC) method was used to identify intergroup differences. Brain regions exhibiting statistically significant differences were selected as regions of interest for further functional connectivity analysis. The partial correlation method was utilized to assess the correlation between abnormal VMHC values in different regions and clinical parameters, with age and sex included as covariates. RESULTS: Patients with AP exhibited reduced VMHC values in the thalamus and elevated VMHC values in the inferior frontal gyrus compared with healthy controls. Subsequent functional connectivity analyses revealed extensive changes in functional networks, predominantly affecting the default, frontoparietal, cerebellar, and pain networks. CONCLUSION: Changes in functional patterns across these brain networks offer novel insights into the neurophysiological mechanisms underlying pain information processing.

2.
J Periodontal Res ; 58(4): 841-851, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37243354

RESUMO

BACKGROUND AND OBJECTIVE: Periodontitis is a multifactorial inflammatory disease that leads to the destruction of supporting structures of the teeth. DNA damage-inducible transcript 3 (DDIT3) plays crucial roles in cell survival and differentiation. DDIT3 regulates bone mass and osteoclastogenesis in femur. However, the role of DDIT3 in periodontitis has not been elucidated. This research aimed to explore the role and mechanisms of DDIT3 in periodontitis. METHODS: DDIT3 gene knockout (KO) mice were generated using a CRISPR/Cas9 system. Experimental periodontitis models were established to explore the role of DDIT3 in periodontitis. The expression of DDIT3 in periodontal tissues was detected by quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC). The alveolar bone phenotypes were observed by micro-CT and stereomicroscopy. The inflammation levels and osteoclast activity were examined by histological staining, immunostaining, and qRT-PCR. Bone marrow-derived macrophages (BMMs) were isolated to confirm the effects of DDIT3 on osteoclast formation and function in vitro. RESULTS: The increased expression of DDIT3 in murine inflamed periodontal tissues was detected. DDIT3 knockout aggravated alveolar bone loss and enhanced expression levels of inflammatory cytokines in murine periodontitis models. Increased osteoclast formation and higher expression levels of osteoclast-specific markers were observed in the inflamed periodontal tissues of KO mice. In vitro, DDIT3 deficiency promoted the formation of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated osteoclasts and the bone resorption activity of mature osteoclasts. CONCLUSIONS: Our results demonstrate that DDIT3 deletion aggravated alveolar bone loss in experimental periodontitis through enhanced inflammatory reactions and osteoclastogenesis. The anti-inflammation and the inhibition of bone loss by DDIT3 in murine periodontitis provides a potential novel therapeutic strategy for periodontitis.


Assuntos
Perda do Osso Alveolar , Reabsorção Óssea , Periodontite , Animais , Camundongos , Perda do Osso Alveolar/patologia , Dano ao DNA , Inflamação/patologia , Osteoclastos/metabolismo , Periodontite/tratamento farmacológico , Ligante RANK/metabolismo
3.
Bioconjug Chem ; 33(7): 1319-1327, 2022 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-35729781

RESUMO

The nontraditional intrinsic fluorescence (NTIF) of polymers containing heteroatoms has gained considerable attention due to its promising applications in label-free bioimaging. Aliphatic hyperbranched polyureas (aBPUs), which have recently shown great promise in the field of nanomedicine, bear controllable urea groups distributed on the branch points and thus are potential candidate luminogens. However, their NTIF properties and how their structures influence the NTIF properties have not been illustrated yet. Here, we addressed these issues by synthesizing a series of aBPUs with different degrees of branching (DBs) or different modifications. aBPUs exhibited an obvious NTIF phenomenon and with the increase of DBs, the NTIF enhanced as well. Chemical modifications either at the branching ends or in the interior of aBPUs could affect the NTIF performances, which were highly dependent on the types of modification. Disruption of the intra-/intermolecular hydrogen-bonding interactions decreased the NTIF. In addition, poly(ethylene glycol) (PEG)-modified aBPUs could self-assemble into nanospheres, and the formation of nanoassembly led to 89% enhancement on NTIF compared with the homogeneous solution of aBPUs-PEG in dimethylformamide (DMF). Finally, aBPUs-PEG nanoassembly demonstrated a capability in realizing label-free material imaging in vitro. These results shed light on the rational design of the polymer structures to achieve desired fluorescence with unconventional luminophores.


Assuntos
Polietilenoglicóis , Polímeros , Fluorescência , Nanomedicina/métodos , Polietilenoglicóis/química , Polímeros/química
4.
Epilepsy Behav ; 55: 184-8, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26627980

RESUMO

INTRODUCTION: Community-based and other epidemiologic studies within the United States have identified substantial disparities in health care among adults with epilepsy. However, few data analyses addressing their health-care access are representative of the entire United States. This study aimed to examine national survey data about adults with epilepsy and to identify barriers to their health care. MATERIALS AND METHODS: We analyzed data from U.S. adults in the 2010 and the 2013 National Health Interview Surveys, multistage probability samples with supplemental questions on epilepsy. We defined active epilepsy as a history of physician-diagnosed epilepsy either currently under treatment or accompanied by seizures during the preceding year. We employed SAS-callable SUDAAN software to obtain weighted estimates of population proportions and rate ratios (RRs) adjusted for sex, age, and race/ethnicity. RESULTS: Compared to adults reporting no history of epilepsy, adults reporting active epilepsy were significantly more likely to be insured under Medicaid (RR=3.58) and less likely to have private health insurance (RR=0.58). Adults with active epilepsy were also less likely to be employed (RR=0.53) and much more likely to report being disabled (RR=6.14). They experience greater barriers to health-care access including an inability to afford medication (RR=2.40), mental health care (RR=3.23), eyeglasses (RR=2.36), or dental care (RR=1.98) and are more likely to report transportation as a barrier to health care (RR=5.28). CONCLUSIONS: These reported substantial disparities in, and barriers to, access to health care for adults with active epilepsy are amenable to intervention.


Assuntos
Epilepsia/terapia , Acessibilidade aos Serviços de Saúde/estatística & dados numéricos , Medicaid , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Pesquisas sobre Atenção à Saúde , Humanos , Masculino , Pessoa de Meia-Idade , Estados Unidos , Adulto Jovem
5.
Artigo em Inglês | MEDLINE | ID: mdl-39068869

RESUMO

In this study, high-performance liquid chromatography was used to determine four components of Shaoyao Gancao Decoction (SGD), and the effect of purification was evaluated using fingerprints, similarity analysis and cell experiments. An effective method for isolation and purification of SGD was established. The adsorption/desorption properties of SGD were evaluated using resin screening, isothermal analysis, adsorption kinetics, and dynamic adsorption-desorption experiments. It was shown that the Langmuir equation fitted the isotherm data well and that a pseudo-second-order model accurately described kinetic adsorption on AB-8 resin. Analysis of thermodynamic parameters showed that the adsorption process was exothermic. Under the optimal process conditions, the concentrations of albiflorin, paeoniflorin, liquiritin and ammonium glycyrrhizinate in the product were 73.05, 134.04, 45.04 and 75.00 mg/g, respectively. The yields of the four components were 71.89 %-86.19 %. Cell experiments showed that the purified SGD retained anti-inflammatory activity. This research lays the foundation for the separation and purification of SGD and subsequent preparation research.


Assuntos
Medicamentos de Ervas Chinesas , Glucosídeos , Monoterpenos , Medicamentos de Ervas Chinesas/química , Medicamentos de Ervas Chinesas/isolamento & purificação , Cromatografia Líquida de Alta Pressão/métodos , Glucosídeos/isolamento & purificação , Glucosídeos/química , Monoterpenos/isolamento & purificação , Monoterpenos/química , Adsorção , Flavanonas/isolamento & purificação , Flavanonas/química , Flavanonas/análise , Animais , Ácido Glicirrízico/isolamento & purificação , Ácido Glicirrízico/química , Ácido Glicirrízico/análise , Hidrocarbonetos Aromáticos com Pontes/química , Hidrocarbonetos Aromáticos com Pontes/isolamento & purificação , Camundongos , Resinas Sintéticas/química , Anti-Inflamatórios/isolamento & purificação , Anti-Inflamatórios/química , Humanos , Células RAW 264.7
6.
Adv Mater ; 35(24): e2210458, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37046183

RESUMO

Germline stem cells (GSCs) are the only cell population capable of passing genetic information to offspring, making them attractive targets in reproductive biology and fertility research. However, it is generally more difficult to introduce exogenous biomolecules into GSCs than other cell types, impeding the exploration and manipulation of these cells for biomedical purposes. Herein, semiconductor polymer dots (Pdots)-based nanocomplex Pdot-siRNA is developed and achieves effective knockdown of target genes in female germline stem cells (FGSCs). Advantage of high fluorescence brightness of Pdots is taken for comprehensive investigation of their cellular uptake, intracellular trafficking, and exocytosis in FGSCs. Importantly, Pdots show excellent biocompatibility and minimally disturb the differentiation of FGSCs. Intracellular Pdots escape from the lysosomes and undergo active exocytosis, which makes them ideal nanocarriers for bioactive cargos. Moreover, Pdot-siRNA can penetrate into 3D ovarian organoids derived from FGSCs and down-regulate the expression levels of target genes. This study investigates the interface between a type of theranostic nanoparticles and FGSCs for the first time and sheds light on the manipulation and medical application of FGSCs.


Assuntos
Nanopartículas , Células-Tronco de Oogônios , Pontos Quânticos , Polímeros , Semicondutores , Exocitose
7.
J Mater Chem B ; 10(18): 3531-3540, 2022 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-35416810

RESUMO

Preventing prosthesis loosening due to insufficient osseointegration is critical for patients with osteoporosis. Endowing implants with immunomodulatory function can effectively enhance osseointegration. In this work, we loaded icariin (ICA) onto 3D porous sulfonated PEEK (SPEEK) via polydopamine (PDA) modification. Modified ICA-PDA@SPEEK not only promoted the polarization of macrophages to the anti-inflammatory M2 type, but also enhanced the osteogenesis of bone mesenchymal stem cells (BMSCs) and inhibited RANKL-induced osteoclastogenesis by regulating cytokine from macrophages. In vivo experiments further showed that ICA-PDA@SPEEK regulated the host immune response and promoted osseointegration in ovariectomized (OVX) rats. The above results demonstrated that ICA-PDA@SPEEK could be an excellent orthopedic biomaterial with immunomodulatory properties.


Assuntos
Osseointegração , Osteogênese , Animais , Benzofenonas , Flavonoides , Humanos , Imunidade , Imunomodulação , Cetonas/farmacologia , Polietilenoglicóis/farmacologia , Polímeros , Ratos
8.
Int Immunopharmacol ; 95: 107532, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33756230

RESUMO

Human multiple myeloma (MM) is a currently incurable haematopoietic malignancies. Our research investigate the anti-tumour effect of iguratimod (IGU) encapsulated in poly(lactic-co-glycolic acid) PLGA nanoparticles (IGU-PLGA-NPs) on MM cells in vitro and in vivo. A significant inhibitory effect of IGU-PLGA-NPs on MM cancer cells and MM CSCs was demonstrated by the Cell Counting Kit-8 (CCK-8) assay. Treatment with IGU-PLGA-NPs induced significant cell cycle arrest at G1 in MM cells and reduced tumour colony formation in MM CSCs. Mechanistically, IGU-PLGA-NPs increase apoptosis in MM cells by activating Caspase-dependent signalling pathway to increase the levels of bax, cytochrome c (cyt-c), caspase-9 and caspase-3 proteins. Moreover, IGU-PLGA-NPs effectively increase ROS production assayed using a DCFH-DA fluorescent probe in MM cells. The data indicate that IGU-PLGA-NPs induce a significant reduction in the tumour volume and a marked increase in the survival rate in a mouse model of multiple myeloma. Overall, our findings indicate that IGU-PLGA-NPs are a potential therapeutic strategy that may contribute to the therapy of MM and elimination of MM CSCs in future clinical trials.


Assuntos
Antineoplásicos/administração & dosagem , Cromonas/administração & dosagem , Mieloma Múltiplo/tratamento farmacológico , Nanopartículas/administração & dosagem , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/administração & dosagem , Sulfonamidas/administração & dosagem , Animais , Apoptose/efeitos dos fármacos , Caspase 3/metabolismo , Caspase 9/metabolismo , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Humanos , Masculino , Camundongos Endogâmicos BALB C , Camundongos Nus , Mieloma Múltiplo/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/efeitos dos fármacos
9.
Cell Prolif ; 52(2): e12556, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30710394

RESUMO

OBJECTIVES: Nanocarriers can greatly enhance the cellular uptake of therapeutic agents to regulate cell proliferation and metabolism. Nevertheless, further application of nanocarriers is often limited by insufficient understanding of the mechanisms of their uptake and intracellular behaviour. MATERIALS AND METHODS: Fluorescent polymer dots (Pdots) are coated with synthetic octaarginine peptides (R8) and are analysed for cellular uptake and intracellular transportation in HeLa cervical cancer cells via single particle tracking. RESULTS: Surface modification with the R8 peptide efficiently improves both cellular uptake and endosomal escape of Pdots. With single particle tracking, we capture the dynamic process of internalization and intracellular trafficking of R8-Pdots, providing new insights into the mechanism of R8 in facilitating nanostructure-based cellular delivery. Furthermore, our results reveal R8-Pdots as a novel type of autophagy inducer. CONCLUSIONS: This study provides new insights into R8-mediated cellular uptake and endosomal escape of nanocarriers. It potentiates biological applications of Pdots in targeted cell imaging, drug delivery and gene regulation.


Assuntos
Endocitose , Corantes Fluorescentes/metabolismo , Oligopeptídeos/metabolismo , Polímeros/metabolismo , Transporte Biológico , Endossomos/metabolismo , Corantes Fluorescentes/análise , Células HeLa , Humanos , Microscopia Confocal , Nanoestruturas/análise , Oligopeptídeos/análise , Imagem Óptica , Polímeros/análise
10.
Acta Biomater ; 86: 323-337, 2019 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-30641289

RESUMO

To address periprosthetic joint infection (PJI), a formidable complication after joint arthroplasty, an implant with excellent osseointegration and effective antibacterial activity has being extensively pursued and developed. In this work, the mouse beta-defensin-14 (MBD-14) was immobilized on the polyetheretherketone (PEEK) surface with three-dimensional (3D) porous structure to improve its antibacterial activity and osseointegration. An in vitro antibacterial evaluation showed that the porous PEEK loaded with MBD-14 wages a durable and effective fight against both Staphylococcus aureus (gram-positive) and Pseudomonas aeruginosa (gram-negative). In addition to the superior antibacterial activity, we found that the enhanced proliferation and osteogenic differentiation of bone mesenchymal stem cells were verified through various in vitro analyses. To evaluate the in vivo bactericidal effect and osseointegration of the samples, the rat femoral models with infection and non-infection were established. The enhanced osseointegration of the MBD-14-loaded samples was found in both two in vivo models. And no bacteria survived on the surfaces of samples with a relatively high MBD-14 concentration. Above results indicate that the 3D porous PEEK coating loaded with MBD-14 simultaneously yields excellent osseointegration while exerting durable and broad-spectrum antibacterial activity. And it paves the way for PEEK to be applied clinically to address PJI. STATEMENT OF SIGNIFICANCE: (1). By using the physio-chemical technique including sulfonation and lyophilization etc., a three-dimensional porous network is developed on polyetheretherketone (PEEK) surface, in which mouse beta-defensin-14 (MBD-14, a broad-spectrum antimicrobial peptide) is then loaded. It endows PEEK with antibacterial activity and osseointegration. (2). Two in vivo animal models with infection and non-infection are used to prove the new bone formation around the samples. (3). Supplementary material also proves that MBD-14 promotes the osteogenic differentiation of BMSCs. However, its potential mechanism needs to be further studied in future. (4). The modified PEEK, including excellent osseointegration and a durable and broad-spectrum antibacterial activity, could be applied clinically to address PJI which is a hot potato for surgeons and patients undergoing total joint arthroplasty.


Assuntos
Antibacterianos/farmacologia , Cetonas/química , Osseointegração/efeitos dos fármacos , Polietilenoglicóis/química , Ácidos Sulfônicos/química , beta-Defensinas/química , Animais , Benzofenonas , Células Cultivadas , Citoesqueleto/efeitos dos fármacos , Citoesqueleto/metabolismo , Feminino , Fêmur/diagnóstico por imagem , Fêmur/efeitos dos fármacos , Fêmur/patologia , Regulação da Expressão Gênica/efeitos dos fármacos , Masculino , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Osteogênese/efeitos dos fármacos , Polímeros , Pseudomonas aeruginosa/efeitos dos fármacos , Ratos Sprague-Dawley , Staphylococcus aureus/efeitos dos fármacos
11.
J Mater Chem B ; 7(36): 5541-5553, 2019 09 18.
Artigo em Inglês | MEDLINE | ID: mdl-31451811

RESUMO

Prevention of implant-associated infections and insufficient bone tissue integration is critical to exploit the immunomodulatory properties and antibacterial effects of implant materials, which have attracted considerable attention. Modulation of the functions of immune cells in different environments is crucial for managing infection and inferior bone integration via immunomodulation. In this work, sodium butyrate, a fermentation product of gut microbiota, was loaded onto 3D porous sulfonated polyetheretherketone (SP) to modulate the immune responses of cells in different environments. Evaluation of in vitro antibacterial effects showed that sodium butyrate-loaded SP exhibited superior antibacterial activity, especially in the samples containing high concentrations of sodium butyrate. Under bacterial stimulation, the phagocytic activity of macrophages increased with an increase in the sodium butyrate concentration via the production of reactive oxygen species (ROS), which favoured bactericidal activity in the implant-associated infection stage. For bacterial elimination, sodium butyrate-containing SP could polarize macrophages to the M2 phenotype and subsequently stimulate anti-inflammatory cytokine secretion, which is considered beneficial for bone regeneration in the tissue repair stage. In vitro osteogenesis was evaluated and the results demonstrated that treatment with sodium butyrate-containing SP increased the expression of osteogenic genes and proteins. An in vivo rat osteomyelitis model was used to evaluate the protective effect of the SP-loaded with sodium butyrate on bone destruction and osteolysis under infection conditions. To study osteogenesis in vivo, a rat femoral model without infection was used. The results indicated that the SP-B2 group exhibited superior anti-infection capacity and induced new bone formation around the implant in vivo. Treatment with sodium butyrate-containing porous SP modulated the macrophage response under different stimuli, thereby serving as a new approach for the design of smart implant materials with superior antibacterial and bone repair properties.


Assuntos
Antibacterianos/farmacologia , Ácido Butírico/química , Cetonas/farmacologia , Polietilenoglicóis/farmacologia , Infecções Relacionadas à Prótese/tratamento farmacológico , Staphylococcus aureus/efeitos dos fármacos , Ácidos Sulfônicos/farmacologia , Animais , Antibacterianos/química , Benzofenonas , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Cetonas/química , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Camundongos , Testes de Sensibilidade Microbiana , Osteogênese/efeitos dos fármacos , Polietilenoglicóis/química , Polímeros , Próteses e Implantes/efeitos adversos , Células RAW 264.7 , Ratos , Ácidos Sulfônicos/química
12.
ACS Appl Mater Interfaces ; 9(25): 21200-21208, 2017 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-28586196

RESUMO

Semiconducting polymer dots (Pdots) have shown great promise in biomedical applications, including biosensing, drug delivery, and live imaging of cells and biomolecules. Insight into the mechanism and regulation of cellular uptake and intracellular metabolism of Pdots is important for the development of superior Pdots-based theranostic nanoconjugates. Herein, we performed real-time imaging of endocytosis and intracellular trafficking of a type of fluorescent Pdots that showed excellent biocompatibility in various types of cells. The endocytic routes and kinetics of Pdots were differently regulated in distinct cell types. Following endocytosis, Pdots were transported in vesicles along microtubule and destined for lysosomes. Furthermore, our results revealed exosome-mediated extracellular release of Pdots and have tracked the dynamic process at the single particle level. These results provide new insight into the design of more effective and selective imaging probes as well as drug carriers.


Assuntos
Endocitose , Espaço Intracelular , Polímeros , Semicondutores
13.
J Endod ; 43(12): 1990-1996, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29032819

RESUMO

INTRODUCTION: The purpose of this study was to investigate the incidence and location of the second mesiobuccal (MB2) root canal of the maxillary first molar and the relationship between the presence of an MB2 canal and the distribution of canal orifices on the pulpal floor with the aid of cone-beam computed tomographic (CBCT) technology. METHODS: A total of 1008 maxillary first molars (548 patients) were randomly selected and analyzed through CBCT imaging. The association between the incidence of MB2 canals and potential impacting factors including sex, side, age, and the distribution of the main root canal orifices on the pulpal floor was explored. The interorifice distances (ie, the length of a line between the center point of any 2 orifices) at the pulpal floor level were measured using Mimics 10.01 software (ImageWorks, Materialise, Belgium). RESULTS: The majority of 3-rooted maxillary first molars showed 2 root canals (85.4%) in the mesiobuccal root. The incidence of MB2 canals had no statistically significant difference between the left and right sides (P > .05) but had a significant association with the patients' sex and age (P < .05). Receiver operating characteristic curve analysis showed a high diagnostic accuracy (the area under the receiver operating characteristic curve = 0.92) of using the distance ratio of the interorifice distance between the main mesiobuccal and the palatal root canal orifices to the interorifice distance between the distobuccal and the palatal root canal orifices to predict the presence of an MB2 canal. A larger distance ratio (>1.26) indicated a highly probable existence of an MB2 canal. In this study, no molar presented an MB2 canal with a distance ratio of less than 1.16, whereas all molars with a ratio greater than 1.37 presented an MB2 canal without exception. A Bland-Altman scatterplot showed great agreement between the distances of the main mesiobuccal and the distobuccal canal orifices and the second mesiobuccal and the distobuccal canal orifices. CONCLUSIONS: Understanding the incidence of MB2 canals and the distribution pattern of canal orifices on the pulpal floor may help clinicians to quickly identify and locate MB2 canals.


Assuntos
Tomografia Computadorizada de Feixe Cônico , Cavidade Pulpar/anatomia & histologia , Cavidade Pulpar/diagnóstico por imagem , Dente Molar/anatomia & histologia , Dente Molar/diagnóstico por imagem , Adolescente , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
14.
ACS Appl Mater Interfaces ; 9(22): 18619-18625, 2017 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-28497682

RESUMO

Nanoparticles (NPs) have shown great promise as intracellular imaging probes or nanocarriers and are increasingly being used in biomedical applications. A detailed understanding of how NPs get "in and out" of cells is important for developing new nanomaterials with improved selectivity and less cytotoxicity. Both physical and chemical characteristics have been proven to regulate the cellular uptake of NPs. However, the exocytosis process and its regulation are less explored. Herein, we investigated the size-regulated endocytosis and exocytosis of carboxylated polystyrene (PS) NPs. PS NPs with a smaller size were endocytosed mainly through the clathrin-dependent pathway, whereas PS NPs with a larger size preferred caveolae-mediated endocytosis. Furthermore, our results revealed exocytosis of larger PS NPs and tracked the dynamic process at the single-particle level. These results indicate that particle size is a key factor for the regulation of intracellular trafficking of NPs and provide new insight into the development of more effective cellular nanocarriers.


Assuntos
Nanopartículas , Clatrina , Sistemas de Liberação de Medicamentos , Endocitose , Tamanho da Partícula , Poliestirenos
15.
Appl Biochem Biotechnol ; 168(1): 174-82, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21976150

RESUMO

Mesoporous materials possess a hexagonal array of uniform mesopores, high surface areas, and moderate acidity. They are one of the important catalysts in the field of catalytic pyrolysis. In this paper, mesoporous materials of Al-MCM-41, La-Al-MCM-41, and Ce-Al-MCM-41 were synthesized, characterized, and tested as catalysts in the cellulose catalytic pyrolysis process using a fixed bed pyrolysis reactor. The results showed that mesoporous materials exhibited a strong influence on the pyrolytic behavior of cellulose. The presence of these mesoporous molecular sieve catalysts could vary the yield of products, which was that they could decrease the yield of liquid and char and increase the yield of gas product, and could promote high-carbon chain compounds to break into low-carbon chain compounds. Mesoporous molecular sieve catalysts were benefit to the reaction of dehydrogenation and deoxidation and the breakdown of carbon chain. Further, La-Al-MCM-41 and Ce-Al-MCM-41 catalysts can produce more toluene and 2-methoxy-phenol, as compared to the non-catalytic runs.


Assuntos
Biocombustíveis/análise , Biotecnologia/métodos , Celulose/metabolismo , Óleos de Plantas/metabolismo , Temperatura , Adsorção , Catálise , Hidrólise , Nitrogênio/química , Porosidade , Propriedades de Superfície , Difração de Raios X
16.
Sheng Wu Gong Cheng Xue Bao ; 27(3): 398-403, 2011 Mar.
Artigo em Zh | MEDLINE | ID: mdl-21650020

RESUMO

Pyrolysis of cellulose with different catalysts has been conducted in a fixed-bed reactor. Micro-mesoporous composite molecular sieves of ZSM-5(38)/A1-MCM-41 with different Si/A1 ratios were prepared under hydrothermal conditions. With powder X-ray diffraction (XRD), the catalyst samples were characterized. GC-MS was used to analyze the bio-oil composition. The effects of catalysts on the pyrolysis product yields were investigated and the results were compared with the results of experiments performed without catalyst under the same pyrolitic conditions. The presence of the catalysts decreased the liquid yield, while increased the moisture content. The major improvement in the quality of bio-oil with the use of catalysts was the increase of DL-2,3-Butanediol. ZSM-5(38)/A1-MCM-41(20) favored the formation of phenol and 2-methoxy-phenol. In addition, these catalysts were all benefit for the generation of small molecular compounds. Also, it was found that ZSM-5(38) was better for the production of C4-C5 compounds. And micro-mesoporous composite molecular sieves mainly promoted the production of C6-C8 compounds.


Assuntos
Celulose/metabolismo , Óleos de Plantas/metabolismo , Dióxido de Silício/química , Zeolitas/química , Catálise , Eliminação de Resíduos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA