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1.
Sensors (Basel) ; 22(4)2022 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-35214349

RESUMO

In this study, the silver mirror reaction was used to coat the silver film on the surface of self-made microstructured fiber (MSF) to stimulate the surface plasmon resonance effect, and Polydimethylsiloxane (PDMS) with a high thermal-optical coefficient was coated on the silver film as temperature-sensitive material. The MSF with silver and PDMS films was coupled with multi-mode fiber on both sides to form the temperature sensor. In this sensor system, the energy is coupled into the cladding of the microstructure fiber by multi-mode fiber, and the surface plasmon resonance can be further excitated in the MSF. When the temperature of the external environment changes, the refractive index of PDMS will also change. At this time, combined with the surface plasmon resonance effect, a resonant absorption peak corresponding to the temperature appears in the transmission spectrum so that the temperature can be measured quickly and accurately. We found that, in the temperature range of 35 °C to 95 °C, the average temperature sensitivity of the sensor during heating and cooling was -0.83 nm/°C and -0.84 nm/°C, respectively. The advantages of this sensor are the simple structure, convenient operation and good reversibility. The relative sensitivity deviation value (RSD = 0.0059) showed that the sensor has high stability. The temperature sensor based on MSF has favorable prospects for use in fields such as medical treatment, biochemical detection and intelligent monitoring.


Assuntos
Prata , Ressonância de Plasmônio de Superfície , Dimetilpolisiloxanos , Refratometria , Prata/química , Temperatura
2.
Bull Environ Contam Toxicol ; 109(3): 470-476, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35441855

RESUMO

The buildup of silver nanoparticles (AgNPs) in soil has raised mounting concerns on their impact on human health. Human are exposed to AgNPs in soils via hand-to-mouth activities (direct exposure) and food consumption (indirect exposure). However, the bioaccessibility of AgNPs under these exposure scenarios remains largely unknown. We used a physiologically based extraction test (PBET) to assess Ag bioaccessibility in AgNP-containing soils and in earthworms (Pheretima guillemi) cultured in these soils. Silver bioaccessibility was 1.2 - 8.4% and 8.1 - 78.7% upon direct exposure and indirect exposure, respectively. These results indicated greater Ag bioaccessibility in earthworms than in soils. Moreover, particle size decreased upon direct exposure, but remained constant upon indirect exposure in wetland soil, as revealed by single particle inductively coupled plasma-mass spectrometry (spICP-MS) analysis. Our results highlight the importance of indirect exposure to NPs.


Assuntos
Nanopartículas Metálicas , Oligoquetos , Poluentes do Solo , Animais , Humanos , Nanopartículas Metálicas/química , Prata/química , Solo/química , Poluentes do Solo/análise
3.
Bull Environ Contam Toxicol ; 107(4): 748-753, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33963438

RESUMO

Microplastics (MPs) are ubiquitously in ecosystem and have evoked wide attention. The potential risk of MPs to the ecosystems is associated with MPs and the additives such as Pb, which serves as a traditional stabilizer. However, the release of Pb from MPs remains largely unknown. In this study, we evaluated the release of Pb from recycled polyvinyl chloride (PVC) under UV-irradiation. The release process was dominated by two processes: H+ facilitated dissolution of Pb, and light-induced hydroxyl radical (·OH) caused C-H bond cleavage from PVC with the generation of alkyl radical. The effects of pH and coexisting low molecular weight organic acids (LMWOAs) were also evaluated. Lower pH speeds up the Pb release from MPs. The LMWOAs act as a filter of UV to restrain the Pb release. Overall, this study shows the release of Pb from recycled PVC MPs and indicates the potential risk of Pb to the environment.


Assuntos
Microplásticos , Poluentes Químicos da Água , Ecossistema , Chumbo , Plásticos , Cloreto de Polivinila
4.
Int J Mol Sci ; 21(24)2020 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-33327419

RESUMO

Expansins, a group of cell wall-loosening proteins, are involved in cell-wall loosening and cell enlargement in a pH-dependent manner. According to previous study, they were involved in plant growth and abiotic stress responses. However, information on the biological function of the expansin gene in moso bamboo is still limited. In this study, we identified a total of 82 expansin genes in moso bamboo, clustered into four subfamilies (α-expansin (EXPA), ß-expansin (EXPB), expansin-like A (EXLA) and expansin-like B (EXPB)). Subsequently, the molecular structure, chromosomal location and phylogenetic relationship of the expansin genes of Phyllostachys edulis (PeEXs) were further characterized. A total of 14 pairs of tandem duplication genes and 31 pairs of segmented duplication genes were also identified, which may promote the expansion of the expansin gene family. Promoter analysis found many cis-acting elements related to growth and development and stress response, especially abscisic acid response element (ABRE). Expression pattern revealed that most PeEXs have tissue expression specificity. Meanwhile, the expression of some selected PeEXs was significantly upregulated mostly under abscisic acid (ABA) and polyethylene glycol (PEG) treatment, which implied that these genes actively respond to expression under abiotic stress. This study provided new insights into the structure, evolution and function prediction of the expansin gene family in moso bamboo.


Assuntos
Genoma de Planta/genética , Ácido Abscísico/farmacologia , Evolução Molecular , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/genética , Estudo de Associação Genômica Ampla , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Poaceae/genética , Polietilenoglicóis/farmacologia , Regiões Promotoras Genéticas/genética , Sintenia
5.
Int J Biol Macromol ; 268(Pt 2): 131916, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38679264

RESUMO

A polylactic acid degrading triacylglycerol lipase (TGL) was identified from Bacillus safensis based on genome annotation and validated by real-time quantitative PCR. TGL displayed optimal activity at pH 9.0 and 55 °C. It maintained stability at pH 9.0 and temperatures 45 °C. The activity of TGL was found to benefit from the presence of potassium sodium ions, and low concentrations of Triton X-100. The TGL could erode the surface of polylactic acid films and increase its hydrophilicity. The hydrolysis products of polylactic acid by TGL were lactate monomer and dimer. TGL contains a classical catalytic triad structure of lipase (Ser77, Asp133, and His156) and an Ala-X-Ser-X-Gly sequence. Compared with some lipases produced by the same genus Bacillus, TGL is highly conserved in its amino acid sequence, mainly reflected in the amino acid residues that exercise the enzyme activity, including the catalytic activity center and the substrate binding sites.


Assuntos
Bacillus , Lipase , Poliésteres , Bacillus/enzimologia , Lipase/química , Lipase/metabolismo , Lipase/genética , Poliésteres/química , Poliésteres/metabolismo , Concentração de Íons de Hidrogênio , Hidrólise , Especificidade por Substrato , Temperatura , Estabilidade Enzimática , Sequência de Aminoácidos , Domínio Catalítico
6.
J Nanosci Nanotechnol ; 13(1): 68-76, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23646699

RESUMO

In this paper, we successfully synthesized amino-terminated poly(ethylene glycol)-block-poly (epsilon-caprolactone) (NH2-PEG-PCL) block copolymer from polyethylene glycol 2000, epsilon-caprolactone (epsilon-CL) and hydrazine hydrate. The obtained copolymer was characterized by nuclear magnetic resonance (1H-NMR), the molecular weight and distribution of NH2-PEG-PCL were characterized by Gel permeation chromatography (GPC). The NH2-PEG-PCL copolymer could self-assemble into micelles in water. Paclitaxel (PTX) loaded NH2-PEG-PCL (PNPP) micelles were prepared by solid dispersion technique without organic solvent. The micelles were characterized by XRD, TEM and Malvern laser particle size. The results of this work indicated that PNPP micelles were uniform and spherical shapes in solution. The average size and zeta potential of PNPP (DL = 8%) in water was about 97.1 +/- 1.2 nm, +13.9 +/- 0.6 mV, respectively. The in vitrodrug release profile of PNPP micelles showed a clear slow-release effect. The results suggested that NH2-PEG-PCL copolymer might be an excellent carrier for hydrophobic drugs such as PTX. In particular, the NH2-PEG-PCL polymer has potential value for modifying with ligands to work as active targeting drug delivery carriers, which has great significance for cancer therapeutics.


Assuntos
Preparações de Ação Retardada/química , Etilenoglicóis/química , Nanocápsulas/química , Nanocápsulas/ultraestrutura , Paclitaxel/química , Poliésteres/química , Antineoplásicos Fitogênicos/administração & dosagem , Antineoplásicos Fitogênicos/química , Difusão , Teste de Materiais , Paclitaxel/administração & dosagem , Tamanho da Partícula
7.
ACS Appl Bio Mater ; 6(12): 5125-5144, 2023 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-38011318

RESUMO

Every year cancer causes approximately 10 million deaths globally. Researchers have developed numerous targeted drug delivery systems (DDSs) with nanoparticles, polymers, and liposomes, but these synthetic materials have poor degradability and low biocompatibility. Because DNA nanostructures have good degradability and high biocompatibility, extensive studies have been performed to construct DDSs with DNA nanostructures as the molecular-layer master frame (MF) assembled via programmable DNA-aided self-assembly for targeted drug release. To learn the progressing trend of self-assembly techniques and keep pace with their recent rapid advancements, it is crucial to provide an overview of their past and recent progress. In this review article, we first present the techniques to assemble the MF of a DDS with solely DNA strands; to assemble MFs with one or more additional type of construction materials, e.g., polymers (including RNA and protein), inorganic nanoparticle, or metal ions, in addition to DNA strands; and to assemble the more complex DNA nanocomplexes. It is observed that both the techniques used and the MFs constructed have become increasingly complex and that the DDS constructed has an increasing number of advanced functions. From our focused review, we anticipate that DDSs with the MF of multiple building materials and DNA nanocomplexes will attract an increasing number of researchers' interests. On the basis of knowledge about materials and functional components (e.g., targeting aptamers/peptides/antibodies and stimuli for drug release) obtained from previously performed studies, researchers can combine more materials with DNA strands to assemble more powerful MFs and incorporate more components to endow DDSs with improved or additional properties/functions, thereby subsequently contributing to cancer prevention.


Assuntos
Nanoestruturas , Neoplasias , Humanos , Nanoestruturas/química , Sistemas de Liberação de Medicamentos , DNA/química , Polímeros , Neoplasias/tratamento farmacológico
8.
Clin Implant Dent Relat Res ; 25(4): 734-742, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-36373771

RESUMO

BACKGROUND: The restoration of dental implants presents a unique challenge due to the intrinsic biomechanical differences between osseointegrated implants and natural teeth, and their subsequent responses to occlusal loading. However, controversy exists regarding the role that occlusion plays in the physiology of the peri-implant complex. PURPOSE: To provide an overview of the scientific literature regarding occlusion as it relates to implant dentistry and peri-implant disease. MATERIALS AND METHODS: This article presents a narrative review on occlusal loading and its potential effects on the peri-implant complex, as well as some generally accepted guidelines for occlusion in implant dentistry. RESULTS AND CONCLUSIONS: Although there is strong evidence linking occlusal factors to mechanical complications of dental implants, the same cannot be said regarding biological complications. There is no clear scientific evidence on the relationship between occlusal overload and peri-implant disease. However, occlusal overload may be an accelerating factor for peri-implant disease in the presence of inflammation. As the biomechanical properties of dental implants differ from that of the natural dentition, modifications to classic concepts of occlusion may be necessary when dental implants are involved. Thus, clinical recommendations are proposed which function to minimize unfavorable occlusal forces on implant restorations and reduce the associated biological and mechanical complications.


Assuntos
Implantes Dentários , Peri-Implantite , Humanos , Implantes Dentários/efeitos adversos , Peri-Implantite/etiologia , Prótese Dentária Fixada por Implante/efeitos adversos , Oclusão Dentária , Causalidade
9.
J Hazard Mater ; 441: 129909, 2023 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-36099736

RESUMO

Soil pollution caused by cadmium (Cd) is a serious concern. Phytoremediation is a popular technology in the remediation of Cd-contaminated soil. Salix matsudana var. matsudana f. umbraculifera Rehd. has been characterized as a high Cd-accumulating and tolerant willow (HCW). Here, transcriptome and proteome profiling, along with morphology analyses were performed to explore molecular cross-talk involved in Cd tolerance. Our results showed that 73%- 83% of the Cd in roots accumulated in the cell walls and root xylem cell walls were significantly thickened. From transcriptome and proteome analysis, a total of 153 up-regulated differentially-expressed genes and 655 up-regulated differentially-expressed proteins were found in common between two comparison groups (1 d and 4 d vs. respective control). Furthermore, phenylpropanoid biosynthesis was identified as a key pathway in response to Cd stress. In this pathway, lignin biosynthesis genes or proteins were significantly up-regulated, and lignin content increased significantly in roots under Cd stress. Two Cd-induced genes cinnamoyl-CoA reductase 1 (SmCCR1) and cinnamyl alcohol dehydrogenase 7 (SmCAD7) from HCW increased the lignin content and enhanced Cd tolerance in transgenic poplar calli. These results lay the foundation for further clarifying the molecular mechanisms of Cd tolerance in woody plants.


Assuntos
Salix , Poluentes do Solo , Cádmio/análise , Cádmio/toxicidade , Lignina , Raízes de Plantas/química , Raízes de Plantas/genética , Proteoma , Salix/genética , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade , Transcriptoma
10.
Chemosphere ; 318: 137991, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36716940

RESUMO

A mesophilic bacterial strain, Bacillus safensis PLA1006, was isolated from landfill soil and was tested for growth on polylactic acid (PLA) emulsion medium. The strain formed clear zones on the medium and produced protease and lipase. The macroscopic morphology of the PLA films was not changed significantly after treatment with Bacillus safensis PLA1006 but the films were whitened. Weight loss of PLA films was about 8% after 30 days of incubation with Bacillus safensis PLA1006 in mineral salt medium. Scanning electron microscopy revealed etching on the surface of PLA film treated by Bacillus safensis PLA1006. This also caused an increase in hydrophilicity of the PLA films surface. Attenuated total reflectance - Fourier transform infrared spectroscopy analysis of PLA films after treated by Bacillus safensis PLA1006 showed no new absorption peaks but a decrease in the intensity of all absorption peaks. The hydrolysis products of PLA by the strain contained monomers and oligomers of lactic acid. Zymogram detection showed that proteases may play a role in the degradation of PLA.


Assuntos
Bacillus , Poliésteres , Poliésteres/química , Bacillus/metabolismo , Bactérias/metabolismo
11.
Nat Commun ; 14(1): 2117, 2023 04 13.
Artigo em Inglês | MEDLINE | ID: mdl-37055470

RESUMO

Biocatalysis is increasingly replacing traditional methods of manufacturing fine chemicals due to its green, mild, and highly selective nature, but biocatalysts, such as enzymes, are generally costly, fragile, and difficult to recycle. Immobilization provides protection for the enzyme and enables its convenient reuse, which makes immobilized enzymes promising heterogeneous biocatalysts; however, their industrial applications are limited by the low specific activity and poor stability. Herein, we report a feasible strategy utilizing the synergistic bridging of triazoles and metal ions to induce the formation of porous enzyme-assembled hydrogels with increased activity. The catalytic efficiency of the prepared enzyme-assembled hydrogels toward acetophenone reduction is 6.3 times higher than that of the free enzyme, and the reusability is confirmed by the high residual catalytic activity after 12 cycles of use. A near-atomic resolution (2.1 Å) structure of the hydrogel enzyme is successfully analyzed via cryogenic electron microscopy, which indicates a structure-property relationship for the enhanced performance. In addition, the possible mechanism of gel formation is elucidated, revealing the indispensability of triazoles and metal ions, which guides the use of two other enzymes to prepare enzyme-assembled hydrogels capable of good reusability. The described strategy can pave the way for the development of practical catalytic biomaterials and immobilized biocatalysts.


Assuntos
Álcool Desidrogenase , Hidrogéis , Hidrogéis/química , Triazóis , Enzimas Imobilizadas/química , Íons , Materiais Biocompatíveis , Biocatálise , Estabilidade Enzimática
12.
ACS Nano ; 16(10): 17157-17167, 2022 10 25.
Artigo em Inglês | MEDLINE | ID: mdl-36200753

RESUMO

Nanoplastics are ubiquitous in ecosystems and impact planetary health. However, our current understanding on the impacts of nanoplastics upon terrestrial plants is fragmented. The lack of systematic approaches to evaluating these impacts limits our ability to generalize from existing studies and perpetuates regulatory barriers. Here, we undertook a meta-analysis to quantify the overall strength of nanoplastic impacts upon terrestrial plants and developed a machine learning approach to predict adverse impacts and identify contributing features. We show that adverse impacts are primarily associated with toxicity metrics, followed by plant species, nanoplastic mass concentration and size, and exposure time and medium. These results highlight that the threats of nanoplastics depend on a diversity of reactions across molecular to ecosystem scales. These reactions are rooted in both the spatial and functional complexities of nanoplastics and, as such, are specific to both the plastic characteristics and environmental conditions. These findings demonstrate the utility of interrogating the diversity of toxicity data in the literature to update both risk assessments and evidence-based policy actions.


Assuntos
Microplásticos , Poluentes Químicos da Água , Ecossistema , Plásticos
13.
Nanotechnology ; 21(21): 215103, 2010 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-20431208

RESUMO

This study aims to develop self-assembled poly(ethylene glycol)-poly(epsilon-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG, PECE) micelles to encapsulate hydrophobic honokiol (HK) in order to overcome its poor water solubility and to meet the requirement of intravenous administration. Honokiol loaded micelles (HK-micelles) were prepared by self-assembly of PECE copolymer in aqueous solution, triggered by its amphiphilic characteristic assisted by ultrasonication without any organic solvents, surfactants and vigorous stirring. The particle size of the prepared HK-micelles measured by Malvern laser particle size analyzer were 58 nm, which is small enough to be a candidate for an intravenous drug delivery system. Furthermore, the HK-micelles could be lyophilized into powder without any adjuvant, and the re-dissolved HK-micelles are stable and homogeneous with particle size about 61 nm. Furthermore, the in vitro release profile showed a significant difference between the rapid release of free HK and the much slower and sustained release of HK-micelles. Moreover, the cytotoxicity results of blank micelles and HK-micelles showed that the PECE micelle was a safe carrier and the encapsulated HK retained its potent antitumor effect. In short, the HK-micelles were successfully prepared by an improved method and might be promising carriers for intravenous delivery of HK in cancer chemotherapy, being effective, stable, safe (organic solvent and surfactant free), and easy to produce and scale up.


Assuntos
Antineoplásicos/química , Compostos de Bifenilo/química , Sistemas de Liberação de Medicamentos/métodos , Lignanas/química , Micelas , Poliésteres/química , Polietilenoglicóis/química , Adenocarcinoma/tratamento farmacológico , Adenocarcinoma/metabolismo , Adenocarcinoma/patologia , Animais , Antineoplásicos/administração & dosagem , Compostos de Bifenilo/administração & dosagem , Processos de Crescimento Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Neoplasias do Colo/tratamento farmacológico , Neoplasias do Colo/metabolismo , Neoplasias do Colo/patologia , Ensaios de Seleção de Medicamentos Antitumorais , Estabilidade de Medicamentos , Medicamentos de Ervas Chinesas/administração & dosagem , Medicamentos de Ervas Chinesas/química , Humanos , Lignanas/administração & dosagem , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Camundongos , Microscopia Eletrônica de Transmissão , Tamanho da Partícula , Poliésteres/administração & dosagem , Poliésteres/síntese química , Polietilenoglicóis/administração & dosagem , Polietilenoglicóis/síntese química , Solubilidade , Sonicação , Difração de Raios X
14.
J Phys Chem B ; 113(30): 10183-8, 2009 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-19572675

RESUMO

This study aims to develop a novel composite drug delivery system (CDDS) for hydrophobic honokiol delivery: honokiol loaded micelles in thermosensitive hydrogel (honokiol micelles/hydrogel) based on biodegradable poly(ethylene glycol)-poly(epsilon-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG, PECE) copolymers. In our work, we found that PECE copolymers with different molecular weight and PEG/PCL ratios could be administered to form micelles or thermosensitive hydrogel, respectively. Honokiol loaded PECE micelles (honokiol micelles) were prepared by self-assembly of biodegradable PECE copolymer (PEG5000-PCL5000-PEG5000) triggered by its amphiphilic characteristic assisted by ultrasonication without using any organic solvents and surfactants. Meanwhile, biodegradable and injectable thermosensitive PECE hydrogel (PEG550-PCL2400-PEG550) with a lower sol-gel transition temperature at around physiological temperature was also prepared successfully. Furthermore, the obtained honokiol micelles/hydrogel CDDS was a free-flowing sol at ambient temperature and became a nonflowing gel at body temperature. The cytotoxicity results showed that the CDDS was a safe carrier and the encapsulated honokiol retained its potent antitumor effect. In addition, the in vitro release profile demonstrated a significant difference between rapid release of free honokiol and much slower and sustained release of honokiol micelles/hydrogel. The results suggested that the CDDS might have great potential applications in cancer chemotherapy.


Assuntos
Compostos de Bifenilo/química , Portadores de Fármacos/química , Hidrogéis/química , Lignanas/química , Poliésteres/química , Polietilenoglicóis/química , Animais , Compostos de Bifenilo/metabolismo , Compostos de Bifenilo/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Portadores de Fármacos/síntese química , Portadores de Fármacos/metabolismo , Portadores de Fármacos/toxicidade , Lignanas/metabolismo , Lignanas/farmacologia , Camundongos , Temperatura
15.
Environ Pollut ; 220(Pt B): 997-1004, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27876416

RESUMO

Extracellular polymeric substances (EPS) isolated from bacteria, are abound of functional groups which can react with metals and consequently influence the immobilization of metals. In this study, we combined with Zn K-edge Extended X-ray Absorption Fine Structure (EXAFS), Fourier Transform Infrared (FTIR) spectroscopy, and High-Resolution Transmission Electron Microscopy (HRTEM) techniques to study the effects of EPS isolated from Bacillus subtilis and Pseudomonas putida on Zn sorption on γ-alumina. The results revealed that Zn sorption on aluminum oxide was pH-dependent and significantly influenced by bacterial EPS. At pH 7.5, Zn sorbed on γ-alumina was in the form of Zn-Al layered doubled hydroxide (LDH) precipitates, whereas at pH 5.5, Zn sorbed on γ-alumina was as a Zn-Al bidentate mononuclear surface complex. The amount of sorbed Zn at pH 7.5 was 1.3-3.7 times higher than that at pH 5.5. However, in the presence of 2 g L-1 EPS, regardless of pH conditions and EPS source, Zn + EPS + γ-alumina ternary complex was formed on the surface of γ-alumina, which resulted in decreased Zn sorption (reduced by 8.4-67.8%) at pH 7.5 and enhanced Zn sorption (increased by 10.0-124.7%) at pH 5.5. The FTIR and EXAFS spectra demonstrated that both the carboxyl and phosphoryl moieties of EPS were crucial in this process. These findings highlight EPS effects on Zn interacts with γ-alumina.


Assuntos
Óxido de Alumínio/química , Zinco/química , Adsorção , Bacillus subtilis/química , Concentração de Íons de Hidrogênio , Hidróxidos , Polímeros/química , Pseudomonas putida/química , Espectroscopia de Infravermelho com Transformada de Fourier , Espectroscopia por Absorção de Raios X
16.
J Hazard Mater ; 308: 21-8, 2016 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-26808239

RESUMO

A knowledge gap concerning the potential effects of extracellular polymeric substances (EPS), a common organic material but highly variable in their composition of microbial origin, on the fate and phytotoxicity of silver nanoparticles (AgNP) still remains. A 48-h root elongation toxicity test showed that AgNP toxicity to wheat Triticum aestivum L. was dramatically alleviated by EPS isolated from Pseudomonas putida, as revealed by 7-59% increase in relative root elongation (RRE), 8-99% increase in root weight, 27-32% decrease in malondialdehyde (MDA) content and 11-43% decrease in H2O2 content compared to the treatment with AgNP in the absence of EPS. This was coincident with 7-69% decrease in root Ag concentrations. Our results showed that EPS could protect wheat seedlings from AgNP toxicity by reducing dissolved Ag concentration ([Ag]diss) and by forming AgNP-EPS complex. The FTIR spectra further showed that the amide, carboxyl, and phosphoryl functional groups of EPS were involved in binding with AgNP and/or Ag(+). All these processes worked simultaneously to reduce AgNP bioavailability, and subsequently mitigate AgNP toxicity. These findings highlight the importance of EPS in AgNP biogeochemistry in the terrestrial environment. EPS could be highly useful in developing strategies to counteract the phytotoxicty of metal-based nanoparticles in crops.


Assuntos
Biopolímeros/farmacologia , Nanopartículas Metálicas/toxicidade , Prata/toxicidade , Triticum/efeitos dos fármacos , Biopolímeros/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Brotos de Planta/efeitos dos fármacos , Brotos de Planta/crescimento & desenvolvimento , Pseudomonas putida/metabolismo , Prata/farmacocinética , Triticum/crescimento & desenvolvimento , Triticum/metabolismo
17.
Clin Cancer Res ; 22(3): 680-90, 2016 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-26832745

RESUMO

PURPOSE: Aldesleukin, recombinant human IL2, is an effective immunotherapy for metastatic melanoma and renal cancer, with durable responses in approximately 10% of patients; however, severe side effects limit maximal dosing and thus the number of patients able to receive treatment and potential cure. NKTR-214 is a prodrug of conjugated IL2, retaining the same amino acid sequence as aldesleukin. The IL2 core is conjugated to 6 releasable polyethylene glycol (PEG) chains. In vivo, the PEG chains slowly release to generate active IL2 conjugates. EXPERIMENTAL DESIGN: We evaluated the bioactivity and receptor binding of NKTR-214 and its active IL2 conjugates in vitro; the tumor immunology, tumor pharmacokinetics, and efficacy of NKTR-214 as a single agent and in combination with anti-CTLA-4 antibody in murine tumor models. Tolerability was evaluated in non-human primates. RESULTS: In a murine melanoma tumor model, the ratio of tumor-killing CD8(+) T cells to Foxp3(+) regulatory T cells was greater than 400 for NKTR-214 compared with 18 for aldesleukin, supporting preferential activation of the IL2 receptor beta over IL2 receptor alpha, due to the location of PEG molecules. NKTR-214 provides a 500-fold greater exposure of the tumor to conjugated IL2 compared with aldesleukin. NKTR-214 showed efficacy as a single agent and provided durable immunity that was resistant to tumor rechallenge in combination with anti-CTLA-4 antibody. NKTR-214 was well tolerated in non-human primates. CONCLUSIONS: These data support further evaluation of NKTR-214 in humans for a variety of tumor types, adding to the repertoire of potent and potentially curative cancer immunotherapies.


Assuntos
Antineoplásicos/farmacologia , Interleucina-2/análogos & derivados , Neoplasias/metabolismo , Neoplasias/patologia , Polietilenoglicóis/farmacologia , Pró-Fármacos , Receptores de Interleucina-2/metabolismo , Proteínas Recombinantes de Fusão/farmacologia , Animais , Antineoplásicos/química , Linfócitos T CD8-Positivos/efeitos dos fármacos , Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/metabolismo , Antígeno CTLA-4/antagonistas & inibidores , Linhagem Celular Tumoral , Modelos Animais de Doenças , Sinergismo Farmacológico , Feminino , Humanos , Memória Imunológica , Interleucina-2/química , Interleucina-2/farmacologia , Linfócitos do Interstício Tumoral , Masculino , Melanoma Experimental , Camundongos , Modelos Moleculares , Conformação Molecular , Neoplasias/tratamento farmacológico , Neoplasias/imunologia , Polietilenoglicóis/química , Ligação Proteica , Receptores de Interleucina-2/química , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes/farmacologia , Linfócitos T Reguladores/efeitos dos fármacos , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Carga Tumoral/efeitos dos fármacos
18.
Bioresour Technol ; 187: 198-204, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25846190

RESUMO

In this work, multiple reuses of Rhodococcus ruber TH3 free cells for the hydration of acrylonitrile to produce acrylamide in a membrane dispersion microreactor were carried out. Through using a centrifuge, the reactions reached 39.9, 39.5, 38.6 and 38.0wt% of the final acrylamide product concentration respectively within 35min in a four cycle reuse of free cells. In contrast, using a stirring tank, free cells could only be used once with the same addition speed of acrylonitrile with a microreactor. Through observing the dissolution behavior of acrylonitrile microdroplets in a free cell solution using a coaxial microfluidic device and microscope, it was found that the acrylonitrile microdroplets with a diameter of 75µm were rarely observed within a length of 2cm channel within 10s, which illustrated that the microreactor can intensify the reaction rate to reduce the inhibition of acrylonitrile and acrylamide.


Assuntos
Acrilamida/metabolismo , Reatores Biológicos/microbiologia , Membranas Artificiais , Reciclagem/métodos , Rhodococcus/classificação , Rhodococcus/metabolismo , Acrilamida/isolamento & purificação , Especificidade da Espécie
19.
Bioresour Technol ; 169: 416-420, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25079206

RESUMO

In this work, a membrane dispersion microreactor was utilized for the hydration of acrylonitrile to produce acrylamide. Through observation using a microscopy, it was found that the acrylonitrile was dispersed into the continuous phase (the aqueous phase contains nitrile hydratase (NHase)) as droplets with a diameter ranged from 25 to 35 µm, hence the mass transfer specific surface area was significantly increased, and the concentration of acrylamide reached 52.5 wt% within 50 min. By contrast, in stirred tanks, the concentration of acrylamide only got 39.5 wt% within 245 min. Moreover, only a few amounts of acrylonitrile were accumulated in this microreactor system. Through optimizing the flow rate, the concentration of acrylamide reached 45.8 wt% within 35 min, the short reaction time greatly weakened the inhibition of acrylonitrile and acrylamide on the enzyme activity, which is suitable for prolonging the life of free cell.


Assuntos
Acrilamida/metabolismo , Acrilonitrila/metabolismo , Biocatálise , Reatores Biológicos , Membranas Artificiais , Água/química , Reatores Biológicos/microbiologia , Hidroliases/metabolismo , Reologia , Rhodococcus/enzimologia , Temperatura
20.
Biomaterials ; 35(25): 6972-85, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24836952

RESUMO

In this study, a composite drug delivery system was developed and evaluated for oral delivery of docetaxel: docetaxel-loaded micelles in pH-responsive hydrogel (DTX-micelle-hydrogel). Docetaxel was successfully loaded in micelles with small particle size of 20 nm and high drug loading of 7.76%, which contributed to the drug absorption in the intestinal tract. The experiments of cytotoxicity on 4T1 cells demonstrated the effective antitumor activity of DTX micelles. Meanwhile, a pH-responsive hydrogel was synthesized and optimized for incorporating the docetaxel micelles. The pH-responsiveness and reversibility of the hydrogel were investigated under the pH conditions of the gastrointestinal tract. Furthermore, the DTX-micelle-hydrogel system showed much quicker diffusion of micelles in simulated intestinal fluid than in simulated gastric fluid, which was mainly caused by the change of pH value. The docetaxel released from the micelle-hydrogel system quite slowly, so it had little influence on the absorption of DTX micelles in small intestine. More important, the pharmacokinetic study revealed that the DTX-micelle-hydrogel significantly improved the oral bioavailability of docetaxel (75.6%) about 10 times compared to DTX micelles, and this increase in bioavailability was probably due to the small intestine targeting release of the pH-responsive hydrogel. Consequently, the oral DTX-micelle-hydrogel system was effective in inhibiting tumor growth in subcutaneous 4T1 breast cancer model, and decreased systemic toxicity compared with intravenous treatment. The apoptosis cells in the immunofluorescent studies and the proliferation-positive cells in the immunohistochemical studies were also consistent with the results. Therefore, the DTX-micelle-hydrogel system might be a promising candidate oral drug for breast cancer therapy.


Assuntos
Neoplasias da Mama/tratamento farmacológico , Sistemas de Liberação de Medicamentos/métodos , Hidrogéis/química , Micelas , Poliésteres/química , Polietilenoglicóis/química , Taxoides/farmacocinética , Administração Oral , Animais , Antineoplásicos/farmacocinética , Apoptose/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Docetaxel , Relação Dose-Resposta a Droga , Feminino , Concentração de Íons de Hidrogênio , Camundongos , Camundongos Endogâmicos BALB C , Nanopartículas/química , Tamanho da Partícula , Ratos , Ratos Sprague-Dawley , Difração de Raios X
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