RESUMO
Microplastics have emerged as a significant global concern, particularly in marine ecosystems. While extensive research has focused on the toxicological effects of microplastics on marine animals and/or their associated microorganisms as two separate entities, the holistic perspective of the adaptability and fitness of a marine animal metaorganism-comprising the animal host and its microbiome-remains largely unexplored. In this study, mussel metaorganisms subjected chronic PS-MPs exposure experienced acute mortality but rapidly adapted. We investigated the response of innate immunity, digestive enzymes and their associated microbiomes to chronic PS-MPs exposure. We found that PS-MPs directly and indirectly interacted with the host and microbe within the exposure system. The adaptation was a joint effort between the physiological adjustments of mussel host and genetic adaptation of its microbiome. The mussel hosts exhibited increased antioxidant activity, denser gill filaments and increased immune cells, enhancing their innate immunity. Concurrently, the gill microbiome and the digestive gland microbiome respective selectively enriched for plastic-degrading bacteria and particulate organic matter-utilizing bacteria, facilitating the microbiome's adaptation. The microbial adaptation to chronic PS-MPs exposure altered the ecological roles of mussel microbiome, as evidenced by alterations in microbial interactions and nutrient cycling functions. These findings provided new insights into the ecotoxicological impact of microplastics on marine organisms from a metaorganism perspective.
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Our study aimed to investigate the immune-enhancing mechanism of the pentadecapeptide (RVAPEEHPVEGRYLV) from Cyclina sinensis (SCSP) in a cyclophosphamide (CTX)-induced murine model of immunosuppression. Our results showed that SCSP treatment significantly increased mouse body weight, immune organ indices, and the production of serum IL-6, IL-1ß, and tumor necrosis factor (TNF)-α in CTX-treated mice. In addition, SCSP treatment enhanced the proliferation of splenic lymphocytes and peritoneal macrophages, as well as phagocytosis of the latter in a dose-dependent manner. Moreover, SCSP elevated the phosphorylation levels of p38, ERK, JNK, PI3K and Akt, and up-regulated IKKα, IKKß, p50 NF-κB and p65 NF-κB protein levels, while down-regulating IκBα protein levels. Our results indicate that SCSP has immune-enhancing activities, and that it can activate the MAPK/NF-κB and PI3K/Akt pathways to enhance immunity in CTX-induced immunosuppressed mice.
Assuntos
Quinase I-kappa B , NF-kappa B , Animais , Ciclofosfamida/toxicidade , Quinase I-kappa B/metabolismo , Quinase I-kappa B/farmacologia , Terapia de Imunossupressão , Interleucina-6 , Camundongos , Inibidor de NF-kappaB alfa/metabolismo , NF-kappa B/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Fator de Necrose Tumoral alfa/metabolismoRESUMO
A triptycene-based microporous organic polymer (MOP) in which 2,6-bis(benzimidazol-2-yl)pyridine (bbp) is incorporated as linkage and coordination site is designed and synthesized. Pd(II) ions are further immobilized in this MOP through the coordination interactions between Pd(II) ion and nitrogen atoms of bbp. The resulting material shows high stability and exhibits excellent heterogeneously catalytic activity for the Suzuki-Miyaura cross-coupling reaction. Its high efficiency can be maintained after being reused for a number of cycles.
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Antracenos/química , Polímeros/química , Catálise , Ligantes , Paládio/química , Espectroscopia Fotoeletrônica , Polímeros/síntese química , PorosidadeRESUMO
To investigate the alleviating effect and mechanism of the docosahexaenoic acid-enriched phosphatidylserine (DHA-PS) on bisphenol A (BPA)-induced liver injury in mice, the murine liver injury model was established by gavage of BPA (5 mg/kg) or co-administration of BPA and DHA-PS (50 mg/kg or 100 mg/kg) for 6 weeks. The results showed that after administration of 100 mg/kg DHA-PS, the liver index, serum levels of AST, ALT, TC, TG, NEFA, and LDL-C in mice were significantly decreased, while HDL-C was significantly increased. The LPS, IL-6, IL-1ß, TNF-α, and MDA levels in liver tissues were effectively down-regulated, and IL-10, SOD, GSH-Px, and CAT levels were effectively up-regulated. The H&E and Oil Red O staining results showed that liver damage was notably repaired and lipid deposition was notably reduced after DHA-PS administration. Furthermore, metabolomics and immunohistochemical studies revealed that DHA-PS mainly regulates glycerophospholipid metabolism and the SIRT1-AMPK pathway to improve metabolic disorders of the liver caused by BPA. Therefore, DHA-PS could potentially alleviate BPA-induced murine liver injury through suppressing inflammation and oxidative stress, and modulating lipid metabolism disorders.
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Fluorescent nanoparticles have attracted much attention over the last two decades. Due to the size- and composition-dependent optical and electrical properties, fluorescent nanoparticles have been emphasized in electronic, optical and biomedical applications. Till now, many kinds of methods have been developed to fabricate diverse fluorescent nanoparticles, which include pyrolysis, template synthesis, hydrothermal synthesis, microemulsion, electrochemical methods and so on. Among them, electrochemical methods are favored for relatively good controllability, ease of operation and mild reaction conditions. By adjusting the applied potential, current, components of the electrolyte and other relevant parameters, the fluorescent nanoparticles could be electrochemically manufactured with tunable sizes, compositions and surface structure, which allows for the modification of electronic and optical properties. Therefore, electrochemical methods are regarded as important means in preparing fluorescent nanoparticles. This review focuses on the recent progress in electrochemical fabrications of fluorescent nanoparticles (together with their optical properties and some applications in optoelectronics and biomedicine).
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Técnicas Eletroquímicas , Corantes Fluorescentes/química , Nanopartículas/química , Compostos Inorgânicos de Carbono/química , Silício/química , Compostos de Silício/químicaRESUMO
BACKGROUND: Protein glycosylated hemoglobin, hemoglobin A1c (HbA1c) binds hemoglobin (Hb) in red blood cells to blood glucose. However, the relationship between Hb and HbA1c remains unclear. AIM: To elucidate their relationship in a nondiabetic population aged ≥ 16 years in the United States, using data from the 1999-2018 National Health and Nutrition Examination Survey. METHODS: This study was based on data from 44560 adults aged ≥ 16 years, excluding those with diabetes. The relationship was estimated using a multivariate regression. We also used piecewise linear regression for subgroup analysis based on age and sex stratification and analysis of the threshold effects of Hb on HbA1c. RESULTS: Hb and HbA1c levels were negatively correlated in the unadjusted model (ß = -0.01; 95%CI: -0.01, -0.01). The correlation was significantly negative when the regression model was minimally regulated and stratified by age and sex, and remained negative when the model was further regulated (more than 10%) to identify covariates with the HbA1c level influence estimates. In subgroup analyses based on age and sex stratification, the association remained negative when the covariates were controlled. A nonlinear relationship was observed between them when the Hb levels reached the tipping point (13.2 g/dL) (adjusted odds ratio, -0.04; 95%CI: -0.05, -0.03) and when the Hb levels exceeded 13.2 g/dL (adjusted odds ratio, -0.10; 95%CI: -0.10, -0.09). CONCLUSION: Our study shows that normal Hb levels are negatively correlated with HbA1c in nondiabetic Americans aged ≥ 16 years.
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OBJECTIVE: To examine the performance of real-time shear wave elastography (RT-SWE) in routine clinical practice. METHODS: This was a prospective study of 500 patients. The elasticity color mode method was judged by a four-mode system. The quantitative parameter method was used to measure the modulus of elasticity of the lesions. Pathologic reports were used as a gold standard to comparatively analyze the diagnostic performance of the two methods. RESULTS: A total of 553 tumors were detected. The average mode value and the modulus of elasticity (Emax) of the benign breast masses was lower than that of malignant masses (p < 0.05). With Emax = 67.4 as the diagnostic threshold value, the sensitivity, specificity, accuracy, negative predictive value, and positive predictive value of the two methods were not statistically significant different (p > 0.05). CONCLUSIONS: The shear wave quantitative parameter method and the elasticity color mode method showed similar performances in the diagnosis of benign and malignant breast masses. The elasticity color mode method is convenient and intuitive, whereas the quantitative parameter method can be used to objectively assess the lesions when it is difficult to score the elasticity of an image, but could not be relied on alone.
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Neoplasias da Mama , Técnicas de Imagem por Elasticidade , Feminino , Humanos , Técnicas de Imagem por Elasticidade/métodos , Ultrassonografia Mamária/métodos , Estudos Prospectivos , Sensibilidade e Especificidade , Reprodutibilidade dos Testes , Mama/diagnóstico por imagem , Mama/patologia , Elasticidade , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/patologia , Diagnóstico DiferencialRESUMO
MicroRNAs (miRNAs) are a class of non-protein coding small RNAs that regulate a gene expression at the post-transcriptional level. Using in silico screening, we found that the 3'-untranslated regions of the P25 gene mRNA are perfectly complementary to nucleotides 2-8 at the 5' end of the miRNA-2b (miR-2b). The expression of miR-2b and the P25 gene in posterior silk gland of the fifth instar larval silkworm was investigated using real-time PCR detection method. The results indicated that expression of the P25 gene was very high in the posterior silk gland during the fifth instar larvae, whereas a level of miR-2b sharply decreased until reaching the lowest one on the 8th day. The expression patterns of miR-2b and P25 gene indicate that miR-2b might act as a fine-tuning regulator of expression of the P25 gene at the post-transcriptional level.
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Bombyx/genética , Fibroínas/genética , Glicoproteínas/genética , RNA Interferente Pequeno/genética , Animais , Bombyx/crescimento & desenvolvimento , Biologia Computacional , Regulação da Expressão Gênica no Desenvolvimento , Larva/genética , Larva/crescimento & desenvolvimentoRESUMO
The Bombyx mori Shadow gene (BmShadow) belongs to the superfamily of cytochrome P450 genes. To elucidate the function of the BmShadow gene and its association with diapause, we employed the CRISPR/Cas9 system to knock out the BmShadow gene in the bivoltine strain Qiufeng. The mutant (BmShadow-/-) was obtained in G2, exhibiting a 42-base deletion corresponded exactly to the amino acids regions from positions 155 to 168. The larvae of BmShadow-/- cannot moult at the pre-moulting stage of the 2nd instar. When the BmShadow-/- larvae were fed with 20E analogue at the late stage of the 2nd instar, they were rescued and developed into the 3rd instar. Rescue experiments indicated that the 20E concentration of BmShadow-/- larvae was significantly lower than that in WT larvae, and the 20E concentration of BmShadow-/- larvae which fed 20E analogue was restored to normal levels. Interestingly, the BmShadow-/- larvae could not moult on the 1st instar when they hatched from eggs after being stored at 5 °C for 40 days or after hibernation, suggesting that the 20E transported from the mother was partially consumed in the diapause maintenance phase. Our study confirmed that BmShadow is involved in 20E synthesis and a 14-amino acids region from position 155 to 168 was essential for its function, also there appears to be no other compensation pathway in vivo, which offered an important potential target locus for the control of silkworm development and the biological control of agricultural and forestry pests.
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Bombyx/genética , Sistema Enzimático do Citocromo P-450/genética , Muda/genética , Aminoácidos/metabolismo , Animais , Sistema Enzimático do Citocromo P-450/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Ecdisterona/genética , Ecdisterona/metabolismo , Proteínas de Insetos/genética , Larva/genéticaRESUMO
This study investigated the possibility of coupling anaerobic hydrolysis in an anaerobic membrane bioreactor (AnMBR) with mixotrophic microalgae cultivation in a membrane photobioreactor (MPBR) for the sustainable treatment of municipal wastewater. Using the hydrolyzed wastewater discharged from AnMBR, Chlorella pyrenoidosa in MPBR grew in a mixotrophic mode and realized rapid growth. During the stable operation, MPBR achieved average carbon capture rate of 42.82â¯mg L-1 d-1 and algal lipid production rate of 19.66â¯mg L-1 d-1. The average reduction in TN, TP, and TOC during stable operation was 96.7%, 98.0%, and 95.9%, respectively. Mass balance analysis showed that the overall system captured 14.76â¯mg of carbon from the atmosphere per liter of wastewater treated. Therefore, this AnMBR-MPBR hybrid system simultaneously realized advanced treatment of municipal wastewater, efficient production of algal lipid, and carbon capture from atmosphere, and thus has a good potential in the sustainable treatment of municipal wastewater.
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Chlorella , Microalgas , Anaerobiose , Biomassa , Hidrólise , Fotobiorreatores , Águas ResiduáriasRESUMO
Hatching is the important process for the life of the metazoan, in which hatching enzyme (HE) plays a key role. In this paper, we cloned the full-length sequence of hatching enzyme-like cDNA from bluish-silkworm-eggs of Bombyx mori (BmHEL) by the method of in silico cloning, SMART cDNA synthesis and RACE-PCR technique. The BmHEL is 974 bp in length, and contains an ORF of 885 bp, encoding 294 amino acids residues. The deduced amino acid sequence of BmHEL has 30.3-47.1% identities to that of HE identified in the other species. Two similar signature sequences of HE gene family harbor in the BmHEL. The BmHEL gene structure is 6-exon-5-intron, and a promoter region with high scores has been predicted, which harbors some basal elements and some embryo-development related transcription factor binding sites. In the silkworm eggs at different developmental stages during incubation, the BmHEL transcripts can be detected and keep at a low level during the early stages, increase dramatically since 7th day of incubation, and reach to the maximum on 9th day. Change of BmHEL transcripts is in accordance with the process of embryo development and hatching, indicated that it plays an important role in these processes. Moreover, BmHEL transcript can be detected in the midgut and testis at larval stage, suggested that BmHEL may have other biological functions. To the best of our knowledge, this is the first report on HE gene in the Lepidoptera insects and will be helpful to provide a molecular basis for understanding the complicated mechanism underlying silkworm hatching.
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Bombyx/embriologia , Bombyx/enzimologia , Metaloendopeptidases/genética , Metamorfose Biológica/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Clonagem Molecular , Biologia Computacional , Primers do DNA/genética , DNA Complementar/genética , Componentes do Gene , Perfilação da Expressão Gênica , Dados de Sequência Molecular , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de DNARESUMO
The small regulatory non-coding RNA molecules, known as microRNAs (miRNAs), have been recognized as potential regulator of gene expression and modulate the gene function at the post-transcriptional level. It is now clear that miRNA biogenesis and function are related to the molecular mechanisms of various clinical diseases, which can potentially regulate every aspect of cellular activity, including differentiation and development, metabolism, proliferation, apoptotic cell death viral infection and tumorgenesis. Here, we review recent work and provide insight into the diverse roles of miRNAs.
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Regulação da Expressão Gênica , MicroRNAs/metabolismo , Animais , Apoptose/genética , Diferenciação Celular/genética , Proliferação de Células , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismo , Humanos , MicroRNAs/genética , Vírus/genética , Vírus/metabolismoRESUMO
A simple and facile method was developed to prepare fluorescent carbon nanocrystals (CNCs) with low cytotoxicity and no photobleaching, by electrooxidation of graphite in aqueous solution.
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Corantes Fluorescentes/síntese química , Corantes Fluorescentes/toxicidade , Grafite/química , Nanopartículas/química , Nanopartículas/toxicidade , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Cães , Eletroquímica , Concentração de Íons de Hidrogênio , Oxirredução , Soluções , Espectrofotometria UltravioletaRESUMO
The hemolymph chymotrypsin inhibitor b1 (CIb1) of silkworm, Bombyx mori, plays an important role in innate immunity. In order to study its encoding gene CIb1, five heterogeneous promoter fragments of 844 bp, 682 bp, 516 bp, 312 bp and 82 bp in length were cloned from genomic DNA of the p50 silkworm strain. Characterization of the CIb1 promoter was performed in vitro using the firefly luciferase gene as reporter. The results showed that CIb1 promoter fragments have transcription activities in the B. mori ovary-derived BmN cell line. The 82 bp fragment (-72 to +10 nt) containing the eukaryotic core promoter elements revealed a basic transcription activity. The Bm1 element, upstream the transcription initiation site, showed a positive regulation function to the CIb1 promoter. CIb1 promoter-like fragments from the genomic DNA of the tetra hybrid silkworm SujuxMinghu provided a natural deletion model for the study of the CIb1 promoter. In vitro analysis indicated that the 132 bp fragment from -517 nt to -386 nt upstream of the transcription initiation site strongly suppressed the transcription activity of the CIb1 promoter, suggesting that the 132 bp fragment harbours strong negative cis-acting elements. Infection of Bombyx mori nucleopolyhedrovirus (BmNPV) increased the activity of the CIb1 promoter, having provided another evidence to the function of CIb1 in the innate immunity of silkworm.
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Bombyx/genética , Quimotripsina/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Proteínas de Insetos/genética , Regiões Promotoras Genéticas , Animais , Clonagem Molecular , Primers do DNA , Genoma , Hemolinfa , Luciferases/metabolismo , Mapeamento por RestriçãoRESUMO
Wood-feeding insects depend heavily on the secretion of a combination of cellulases, mainly endoglucanases and other glucanases such as exoglucanases and xylanases, to achieve efficient digestion of the cellulose of cellulosic materials. In this paper, we report a novel cellulose Bh-EGaseI belonging to the glycoside hydrolase family 45(gh45-1) obtained from the beetle Batocera horsfieldi. The Bh-EGaseI gene spans 714 bp and consists of three exons coding 237 amino acid residues. The cDNA encoding Bh-EGaseI was expressed as 25 KDa in baculovirus-infected Bombyx mori larvae. The expression products of Bh-EGaseI from larval hemolymph showed a specific enzymatic activity of approximately 1030.87 IU per mg. The enzyme was active over a wide range of pH and temperatures; optimal activity was observed at 40 °C and pH 4.0. The effects of ions on Bh-EGaseI activity were also studied, and results indicated that activity decreased to different extents upon addition of ions. Investigations on Bh-EGaseI facilitate their potential application in the production of bioenergy and biomaterials from cellulosic biomass in the future.
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Celulase , Besouros , Proteínas de Insetos , Animais , Celulase/biossíntese , Celulase/química , Celulase/genética , Celulase/isolamento & purificação , Clonagem Molecular , Besouros/enzimologia , Besouros/genética , Expressão Gênica , Proteínas de Insetos/biossíntese , Proteínas de Insetos/química , Proteínas de Insetos/genética , Proteínas de Insetos/isolamento & purificação , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificaçãoRESUMO
The "Ming" lethal egg mutant (l-em) is a vitelline membrane mutant in silkworm, Bombyx mori. The eggs laid by the l-em mutant lose water, ultimately causing death within an hour. Previous studies have shown that the deletion of BmEP80 is responsible for the l-em mutation in silkworm, B. mori. In the current study, digital gene expression (DGE) was performed to investigate the difference of gene expression in ovaries between wild type and l-em mutant on the sixth day of the pupal stage to obtain a global view of gene expression profiles using the ovaries of three l-em mutants and three wild types. The results showed a total of 3,463,495 and 3,607,936 clean tags in the wild type and the l-em mutant libraries, respectively. Compared with those of wild type, 239 differentially expressed genes were detected in the l-em mutant, wherein 181 genes are up-regulated and 58 genes are down-regulated in the mutant strain. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis results showed that no pathway was significantly enriched and three pathways are tightly related to protein synthesis among the five leading pathways. Moreover, the expression profiles of eight important differentially expressed genes related to oogenesis changed. These results provide a comprehensive gene expression analysis of oogenesis and vitellogenesis in B. mori which facilitates understanding of both the specific molecular mechanism of the 1-em mutant and Lepidopteran oogenesis in general.
Assuntos
Bombyx/genética , Proteínas de Insetos/genética , Ovário/metabolismo , Animais , Bombyx/metabolismo , Etiquetas de Sequências Expressas , Feminino , Perfilação da Expressão Gênica , Genes Letais , Proteínas de Insetos/metabolismo , Anotação de Sequência Molecular , Mutação , Óvulo/metabolismo , Pupa/genética , Pupa/metabolismo , Transcriptoma , Membrana Vitelina/metabolismoRESUMO
PURPOSE: To compare the diagnostic performance of 5-point scoring system and strain ratio by sonoelastography in the assessment of solid breast lesions. MATERIAL AND METHODS: One hundred and eighty-seven solid masses in 155 patients were scanned by two-dimensional ultrasonography and sonoelastography. Elasticity scores were determined with a 5-point scoring method, and the strain ratio was based on the comparison of the average strain measured in the lesion with the adjacent breast tissue in the same depth. Pathological results were taken as gold standards to compare the diagnostic efficacy of two methods with clinical diagnostic test and receiver operating characteristic (ROC) curves. RESULTS: Among 187 lesions, 130 were benign and 57 were malignant. The mean scores (1.62±0.69 vs 4.07±0.26, P<0.05) and strain ratios (2.06±1.27 vs 6.66±4.62, P<0.05) were significantly higher of malignant than benign lesions. The area under the curve for the 5-point scoring system and for strain ratio-based elastographic analysis was 0.892 and 0.909, respectively (P>0.05). For 5-point scoring, sonoelastography had 84.2% sensitivity, 84.6% specificity, 84.5% accuracy, 70.6% positive predictive value and 92.4% negative predictive value. When a cutoff point of 3.06 was used, sensitivity, specificity, accuracy, positive and negative predictive values were 87.7%, 88.5%, 88.2%, 76.9% and 94.3%, respectively for the strain ratio (P>0.05). CONCLUSIONS: The 5-point scoring system and strain ratio has similar diagnostic performance, and the strain ratio could be more objective to differentiate the masses when those masses were difficult to be judged by using 5-point scoring system in sonoelastographic images.
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Algoritmos , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/fisiopatologia , Técnicas de Imagem por Elasticidade/métodos , Interpretação de Imagem Assistida por Computador/métodos , Ultrassonografia Mamária/métodos , Adolescente , Adulto , Idoso , Módulo de Elasticidade , Feminino , Humanos , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Índice de Gravidade de DoençaRESUMO
The major-groove BINOL-amino alcohol (S)-6 shows greatly enhanced fluorescence over the minor-groove one (S)-3. The study of a series of the major-groove BINOL-amino alcohol compounds demonstrates that the commonly accepted acid inhibition of the PET fluorescence quenching of aryl-amine compounds is not involved in the BINOL-amine sensors.
RESUMO
The performance of electrochemical sensor is related to the surface structure of electrode. Electrochemical treatment was often used to improve the performance of glassy carbon electrodes (GCEs) for the simplicity of operation. The densely compact oxide film formed on the surface of the electro-oxidized glassy carbon electrodes (GCEs-ox) could be changed to be porous by following electro-reduction of the GCEs-ox obtaining the totally reduced GCEs-ox (GCEs-re). The GCEs-re with a porous film exhibited high sensitivity in detecting epinephrine (EP) accompanying with poor stability and incapability of anti-interference from negatively charged ascorbic acid (AA) because both of AA and EP could permeate the porous film. Compared to the GCEs-re, the GCEs-ox with a densely compact film displayed relatively lower sensitivity but higher stability. To combine the advantages of both porous and densely compact oxide films, a partially reduced GCE-ox (GCE-ox-re) with an oxide film porous outer and densely compact inner was designed by controlling the electro-reduction time and potential, which will provide a new strategy for improving the performance of GCEs. The GCEs-ox-re exhibited high sensitivity, excellent stability and high selectivity in the detection of EP. In the presence of 0.1 mM AA, the anodic peak current of EP was directly proportional to its concentration in the range of 8.0x10(-9)-2.0x10(-7) M and EP as low as 2.0x10(-9) M could be detected.
Assuntos
Técnicas Biossensoriais/métodos , Ácido Ascórbico/análise , Técnicas Biossensoriais/estatística & dados numéricos , Carbono , Técnicas Eletroquímicas , Eletrodos , Epinefrina/análise , Vidro , Microscopia de Força Atômica , Oxirredução , Sensibilidade e Especificidade , Propriedades de SuperfícieRESUMO
Well-defined polymethylene-block-polystyrene (PM-b-PS) diblock copolymers were synthesized via a combination of living polymerization of ylides and atom transfer radical polymerization (ATRP) of styrene. A series of hydroxyl-terminated polymethylenes (PM-OHs) with different molecular weight and narrow molecular weight distribution were prepared using living polymerization of ylides following efficient oxidation in a quantitive functionality. Then, the macroinitiators (PM-MIs ($\overline M _{\rm n}$ = 1 900-15 000; PDI = 1.12-1.23)) transformed from PM-OHs in ≈ 100% conversion initiated ATRPs of styrene to construct PM-b-PS copolymers. The GPC traces indicated the successful extension of PS segment ($\overline M _{\rm n}$ of PM-b-PS = 5 000-41 800; PDI = 1.08-1.23). Such copolymers were characterized by (1) H NMR and DSC.