Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Resultados 1 - 20 de 25
Filtrar
1.
Rev Cardiovasc Med ; 24(2): 41, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-39077415

RESUMEN

Background: Carotid-femoral pulse wave velocity (cfPWV) and ejection duration (ED) have different impacts on target organ damage (TOD). The aim of this study was to determine the relationship of cfPWV and ED with TOD. Methods: A total of 1254 patients (64.27% males) from Ruijin Hospital were enrolled in this study from December 2018 to August 2022. Medical records, blood samples and urine samples were collected. The cfPWV was measured and ED was generated using SphygmoCor software (version 8.0, AtCor Medical, Sydney, Australia). TOD including left ventricular hypertrophy (LVH), microalbuminuria, chronic kidney disease (CKD), and abnormality of carotid intima-media thickness (CIMT) were evaluated. Results: Multiple stepwise linear regression models of cfPWV and ED (individually or together) showed that cfPWV was positively correlated with left ventricular mass index (LVMI) ( ß = 0.131, p = 0.002) and Log (albumin-creatinine ratio, ACR) ( ß = 0.123, p = 0.004), while ED was negatively correlated with LVMI ( ß = -0.244, p < 0.001) and positively correlated with the estimated glomerular filtration rate (eGFR) ( ß = 0.115, p = 0.003). When cfPWV and ED were added separately or together in multiple stepwise logistic regression models, cfPWV was associated with CKD [odds ratio (OR) = 1.240, 95% confidence interval (CI) 1.055-1.458, p = 0.009], while ED was associated with LVH (OR = 0.983, 95% CI 0.975-0.992, p < 0.001). In the control group with normal cfPWV and normal ED, LVH was significantly lower in patients with high ED (OR = 0.574, 95% CI 0.374-0.882, p = 0.011), but significantly elevated in those with high cfPWV and low ED (OR = 6.799, 95% CI 1.305-35.427, p = 0.023). Conclusions: cfPWV was more strongly associated with renal damage, while ED was more strongly associated with cardiac dysfunction. cfPWV and ED affect each other, and together have an effect on LVH.

2.
BMC Endocr Disord ; 23(1): 200, 2023 Sep 19.
Artículo en Inglés | MEDLINE | ID: mdl-37726685

RESUMEN

OBJECTIVE: Diabetes foot ulcer (DFU) is a serious complication of diabetes, which can lead to significant mortality and amputation rate. Our previous study found circ_072697 was highly expressed in DFU tissues, but the regulatory mechanism of circ_072697 in DFU remains unclear. METHODS: The relative expressions of circ_072697, miR-3150a-3p, and KDM2A in DFU patients or advanced glycation end products (AGEs)-treated HaCaT cells (used as DFU cell model) were determined by using qRT-PCR. Cell proliferation and migration abilities were determined by using CCK-8 and Transwell assays. The interaction between miR-3150a-3p with circ_072697 or KDM2A were verified by RNA immunoprecipitation (RIP) and dual-luciferase reporter assays. Furthermore, the protein expression of genes involved in MAPK signaling pathway was detected by western blot. RESULTS: The expression of circ_072697 was significantly upregulated in DFU tissues, while the expression of miR-3150a-3p was downregulated. Circ_072697 knockdown promoted the proliferation and migration of AGEs-treated HaCaT cells. miR-3150a-3p was confirmed as a target of circ_072697 and its inhibitor reversed the promotion effects of circ_072697 knockdown on biological behavior of cells. In addition, KDM2A was considered as a target of miR-3150a-3p and it was highly expressed in DFU samples. Importantly, circ_072697 could regulate KDM2A expression through sponging miR-3150a-3p, and this axis had effect on the MAPK signaling pathway. CONCLUSIONS: Overall, circ_072697 regulated the biological behaviors of keratinocytes in DFU via miR-3150a-3p/KDM2A axis and MAPK signaling pathway, revealing a new insight into the pathogenesis and potential therapeutic targets of DFU.


Asunto(s)
Pie Diabético , Proteínas F-Box , MicroARNs , Humanos , Células HaCaT , Pie Diabético/genética , Proliferación Celular , Productos Finales de Glicación Avanzada/farmacología , MicroARNs/genética , Histona Demetilasas con Dominio de Jumonji/genética
3.
Genomics ; 114(4): 110387, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-35569732

RESUMEN

Soybean mosaic virus (SMV) strain SC11 was prevalent in middle China. Its resistance was controlled by a Mendelian single dominant gene RSC11K in soybean Kefeng-1. This study aimed at mapping RSC11K and identifying its candidate gene. RSC11K locus was mapped ~217 kb interval between two SNP-linkage-disequilibrium-blocks (Gm02_BLOCK_11273955_11464884 and Gm02_BLOCK_11486875_11491354) in W82.a1.v1 genome using recombinant inbred lines population derived from Kefeng-1 (Resistant) × NN1138-2 (Susceptible), but inserted with a ~245 kb segment in W82.a2.v1 genome. In the entire 462 kb RSC11K region, 429 SNPs, 142 InDels and 34 putative genes were identified with more SNPs/InDels distributed in non-functional regions. Thereinto, ten genes contained SNP/InDel variants with high and moderate functional impacts on proteins, among which Glyma.02G119700 encoded a typical innate immune receptor-like kinase involving in virus disease process and responded to SMV inoculation, therefore was recognized as RSC11K's candidate gene. The novel RSC11K locus and candidate genes may help developing SMV resistance germplasm.


Asunto(s)
Resistencia a la Enfermedad , Glycine max , Mapeo Cromosómico , Resistencia a la Enfermedad/genética , Genes de Plantas , Enfermedades de las Plantas , Potyvirus , Glycine max/genética
4.
Int Wound J ; 18(3): 323-331, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33314661

RESUMEN

We aimed to explore the mechanism of circular RNAs (circRNAs) and provide potential biomarkers for molecular therapy of diabetic foot ulcers (DFU). Gene expression profile of GSE114248, including five normal samples and five DFU samples, was downloaded from GEO database. Differentially expressed circRNAs (DEcircRNAs) between two groups were identified. Then, DEcircRNA-miRNA and miRNA-mRNA interaction was revealed, followed by the circRNA-miRNA-mRNA network construction. Moreover, functional and pathway analysis were performed based on mRNAs, followed by the DM-related pathway exploration. Specific binding sites for key circRNAs and associated miRNAs were under investigation. Finally, RT-qPCR was used to verify the candidate the relative expression level of circRNA between normal tissues and DFU. Totally, 65 DEcircRNAs were revealed between two groups, followed by 113 circRNA-miRNA-mRNA interactions explored. The mRNAs in these interactions were mainly assembled in functions like cell proliferation and pathways. Moreover, a total of 11 DM-related pathways were revealed. Finally, circRNA-miRNA specific binding-site analysis revealed two key circRNAs, for example, circRNA_072697 and circRNA_405463, corresponding to their miRNAs. These two circRNAs were novel biomarkers for DFU. circRNA_072697 acted as a sponge of miR-3150a-3p in the progression of DFU via regulating KRAS. MAPK signaling pathway might contribute to the development of DFU.


Asunto(s)
Diabetes Mellitus , Pie Diabético , MicroARNs , ARN Circular , Biología Computacional , Diabetes Mellitus/metabolismo , Redes Reguladoras de Genes , Humanos , ARN Mensajero
5.
Cell Immunol ; 294(1): 39-43, 2015 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-25670394

RESUMEN

Two independent Chinese cohorts were used to study the genetic association between the interleukin-23A (IL-23A) gene polymorphism (rs11171806) and susceptibility to Graves' disease (GD). The initial Shanghai cohort consisted of 712 unrelated patients with GD and 705 healthy control subjects, and the replication cohort from Xiamen Island included 433 patients with GD and 410 healthy control subjects. The serum concentration of IL-23 in GD patients was measured significantly higher than in health controls. Moreover in the subgroup analysis, higher concentrations of IL-23 were identified in patients of older age (⩾40 years) and female gender. We also performed an association study with the IL-23 gene polymorphism rs11171806 in both cohorts, in Shanghai cohorts, the frequencies of rs11171806 alleles were strongly different between Graves' disease patients (G 95.7% and A 4.3%) and healthy controls (G 97.7% and A 2.3%) (P=2.6×10(-3), OR=1.93 (95% CI: 1.25-2.97)), and in Xiamen cohorts, the proportion of individuals carrying the A allele of rs11171806 was the same significantly higher in Graves' disease patients than in controls [Graves' disease vs. control, 4.8% vs. 4.3%, OR=2.15 (95% CI: 1.23-3.79), P(allele)=6.3×10(-3)]. The distribution of rs11171806 genotype was also investigated in subgroups according to the age and gender. All of these findings suggested that IL-23 may play an important role in the development of GD, and the IL-23A gene is a genetic risk marker for GD in Han Chinese population.


Asunto(s)
Enfermedad de Graves/epidemiología , Subunidad p19 de la Interleucina-23/sangre , Subunidad p19 de la Interleucina-23/genética , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Envejecimiento/sangre , Envejecimiento/inmunología , Pueblo Asiatico/genética , Niño , Estudios de Cohortes , Femenino , Predisposición Genética a la Enfermedad , Enfermedad de Graves/genética , Enfermedad de Graves/inmunología , Humanos , Masculino , Persona de Mediana Edad , Polimorfismo de Nucleótido Simple , Riesgo , Factores Sexuales , Adulto Joven
6.
J Mater Chem B ; 11(41): 9912-9921, 2023 10 25.
Artículo en Inglés | MEDLINE | ID: mdl-37850305

RESUMEN

Ligation efficiency in a surface-based DNA click chemistry (CuAAC) reaction is extremely restricted by the orientation and density of probes arranged on a heterogeneous surface. Herein, we engineer DNA tetrahedral nanostructure (DTN)-corbelled click chemistry to trigger a hybridization chain reaction (HCR) assembling a large-scale of nanozymes for ratiometric fluorescence detection of DNA adenine methyltransferase (Dam). In this study, a DNA tetrahedron structure with an alkynyl modifying pendant DNA probe (Alk-DTN) is designed and assembled on a magnetic bead (MB) as a scaffold for click chemistry. When a CuO NP-encoded magnetic nanoparticle (CuO-MNP) substrate was methylated by Dam, CuO NPs were released and turned into a mass of Cu+. The Cu+ droves azido modifying lDNA (azide-lDNA) to connect with the Alk-DTN probe on the MB through the click reaction, forming an intact primer to initiate the HCR. The HCR product, a rigid structure double-stranded DNA, periodically assembles glucose oxidase mimicking gold nanoparticles (GNPs) into a large-scale of nanozymes for catalyzing the oxidation of glucose to H2O2. NH2-MIL-101 MOFs, a fluorescent indicator and a biomimetic catalyst, activated the product H2O2 to oxidize o-phenylenediamine (oPD) into visually detectable 2,3-diaminophenazine (DAP). The change of the signal ratio between DAP and NH2-MIL-101 is proportional to the methylation event corresponding to the MTase activity. In this study, the DTN enhances the efficiency of the surface-based DNA click reaction and maintains the catalytic activities of gold nanoparticle nanozymes due to the intrinsic nature of mechanical rigidity and well-controlled orientation and well-adjusted size. Large-scale assembly of nanozymes circumvents the loss of natural enzyme activity caused by chemical modification and greatly improves the amplification efficiency. The proposed biosensor displayed a low detection limit of 0.001 U mL-1 for Dam MTase due to multiple amplification and was effective in real samples and methylation inhibitor screening, providing a promising modular platform for bioanalysis.


Asunto(s)
Oro , Nanopartículas del Metal , Oro/química , Química Clic , Peróxido de Hidrógeno , Nanopartículas del Metal/química , ADN/química , Metiltransferasas , Proteínas Tirosina Quinasas Receptoras
7.
Anal Methods ; 15(37): 4798-4810, 2023 Sep 28.
Artículo en Inglés | MEDLINE | ID: mdl-37724459

RESUMEN

Given the toxicity of arsenic, there is an urgent need for the development of efficient and reliable detection systems. Raman spectroscopy, a powerful tool for material characterization and analysis, can be used to explore the properties of a wide range of different materials. Surface-enhanced Raman spectroscopy (SERS) can detect low concentrations of chemicals. This review focuses on the progress of qualitative and quantitative studies of the adsorption processes of inorganic arsenic and organic arsenic in aqueous media using Raman spectroscopy in recent years and discusses the application of Raman spectroscopy theory simulations to arsenic adsorption processes. Sliver nanoparticles are generally used as the SERS substrate to detect arsenic. Inorganic arsenic is chemisorbed onto the silver surface by forming As-O-Ag bonds, and the Raman shift difference in the As-O stretching (∼60 cm-1) between As(V) and As(III) allows SERS to detect and distinguish between As(V) and As(III) in groundwater samples. For organic arsenicals, specific compounds can be identified based on spectral differences in the vibration modes of the chemical bonds. Under the same laser excitation, the intensity of the Raman spectra for different arsenic concentrations is linearly related to the concentration, thus allowing quantitative analysis of arsenic. Molecular modeling of adsorbed analytes via density functional theory calculation (DFT) can predict the Raman shifts of analytes in different laser wavelengths.

8.
Artículo en Inglés | MEDLINE | ID: mdl-32328036

RESUMEN

Objective: To explore the most suitable calculation method for insulin dosage in an insulin tolerance test (ITT) and to evaluate the clinical application value of the optimization coefficient (γ). Methods: In this study, 140 adult patients with congenital growth hormone deficiency (GHD) or acquired hypopituitarism were randomized into the following two groups: the conventional group (n = 70) and the optimized group (n = 70). Oral glucose tolerance tests (OGTTs), insulin release tests (IRTs), and ITTs were conducted. For ITTs, insulin doses were the product of body weight (kg) and related coefficient (0.15 IU/kg for the control group and γ IU/kg for the optimized group, respectively). Notably, γ was defined as -0.034 + 0.000176 × AUCINS + 0.009846 × BMI, which was based on our previous study. Results: In the ITTs, the rate of achieving adequate hypoglycemia with a single insulin dose was significantly higher for the optimized group compared with the conventional group (92.9 vs. 60.0%, P < 0.001). The optimized group required higher initial doses of insulin (0.23 IU/kg). Meanwhile, the two groups did not differ significantly in their nadir blood glucose (1.9 vs. 1.9 mmol/L, P = 0.828). Conclusion: This study confirmed that the proposed optimized calculation method for insulin dosage in ITTs led to more efficient hypoglycemia achievement, without increasing the incidence of serious adverse events.


Asunto(s)
Glucemia/efectos de los fármacos , Técnicas de Diagnóstico Endocrino/normas , Cálculo de Dosificación de Drogas , Resistencia a la Insulina , Insulina/administración & dosificación , Adulto , Glucemia/metabolismo , Calibración , Enanismo Hipofisario/sangre , Enanismo Hipofisario/diagnóstico , Enanismo Hipofisario/metabolismo , Femenino , Prueba de Tolerancia a la Glucosa/métodos , Prueba de Tolerancia a la Glucosa/normas , Humanos , Hipoglucemia/sangre , Hipoglucemia/diagnóstico , Hipoglucemia/metabolismo , Hipopituitarismo/sangre , Hipopituitarismo/diagnóstico , Hipopituitarismo/metabolismo , Masculino , Adulto Joven
9.
Polymers (Basel) ; 11(5)2019 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-31064060

RESUMEN

Wind power generation is an environmentally friendly way to produce electricity, but wind turbine blades that are prone to freeze in winter will reduce the efficiency of the generator. Therefore, the preparation of anti-icing blades is important and essential. Herein, anti-icing polytetrafluoroethylene (PTFE)/heat-shrinkable polyvinyl chloride (HSPVC) composite film was prepared by depositing a PTFE coating on the surface of HSPVC film via vacuum thermal evaporation. HSPVC films were pretreated respectively by argon and carbon tetrafluoride (CF4) plasma cleaning to introduce new groups and change their surface energy. After that, PTFE coating with a thickness of about 4 µm was deposited on the surface of HSPVC, obtaining a superhydrophobic surface with an apparent water contact angle of 150°. The results demonstrated that the breaking strength of the PTFE/HSPVC composite film using CF4 plasma pretreatment decreased by only 3.47% after exposing to ultraviolet light with the power of 1000 W for 5 min, suggesting an excellent anti-ultraviolet property. Furthermore, compared with the pristine films, the PTFE/HSPVC composite films exhibited better adhesive strength, super anti-icing property even after 10 icing-deicing cycles, and excellent dynamic anti-icing performance. The PTFE/HSPVC composite film with good adhesive strength, anti-ultraviolet, and anti-icing properties has prospective applications in packaging of wind turbine blades.

10.
J Colloid Interface Sci ; 311(2): 456-60, 2007 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-17451737

RESUMEN

In this article, we report a simple wet-chemical method to prepare silver microflowers and large spherical particles. The formation of the two different microstructures of silver is based on the reduction of AgNO(3) by para-phenylenediamine in aqueous medium at room temperature. The controlling of the silver microstructures can be achieved only by adjusting the concentration of the reactants. It is found that the two different silver microstructures display opposite wetting properties. Large spherical silver particles exhibit superhydrophilic properties with a contact angle (CA) of close to 0 degrees, microflower-like silver particles exhibit highly hydrophobic properties with CA about 132 degrees. X-ray diffraction (XRD), X-ray photoelectron spectra (XPS) and UV-vis spectra are used to characterize the chemical structure of the obtained products.


Asunto(s)
Plata/química , Humectabilidad , Interacciones Hidrofóbicas e Hidrofílicas , Tamaño de la Partícula , Nitrato de Plata/química , Análisis Espectral , Electricidad Estática , Propiedades de Superficie , Difracción de Rayos X
11.
J Steroid Biochem Mol Biol ; 174: 141-145, 2017 11.
Artículo en Inglés | MEDLINE | ID: mdl-28847746

RESUMEN

17ß-Hydroxysteroid dehydrogenase 3 deficiency is a rare autosomal recessive cause of 46, XY disorders of sex development resulting from HSD17B3 gene mutations, however, no case has been reported in East Asia. The aim of this study was to report three Chinese 46, XY females with 17ß-HSD3 deficiency in a single center and perform a systematic review of the literature. Clinical examination, endocrine evaluation and HSD17B3 gene sequencing were performed in the three Chinese phenotypically females (two sisters and one unrelated patient). Relevant articles were searched by using the term "HSD17B3" OR "17beta-HSD3 gene" with restrictions on language (English) and species (human) in Pubmed and Embase. All the three phenotypically female subjects showed 46, XY karyotype, inguinal masses, decreased testosterone and increased androstenedione. Two novel homozygous mutations (W284X and c.124_127delTCTT) in HSD17B3 gene were identified. A systematic review found a total of 121 pedigrees/158 patients, with 78.5% (124/158) of patients assigned as females, 15.2% (24/158) from females to males, and 5.1% (8/158) raised as males. The most common mutation was c.277+4C>T (allele frequency: 25/72) for patients from Europe, and R80Q (allele frequency: 21/54) for patients from West Asia. The testicular histology showed normal infantile testicular tissue in 100% (9/9) infantile patients, normal quantity germ cells in 44.4% (8/18) prepubertal patients and 19.0% (4/21) pubertal and adult patients. We reported the first East Asian 17ß-hydroxysteroid dehydrogenase 3 deficiency cases. Additional literature reviews found founder effects among patients with different ethnic background and early orchiopexy may benefit fertility in patients assigned as males. These findings may significantly expand the clinical, ethnic and genetic spectrum of 17ß-hydroxysteroid dehydrogenase 3 deficiency.


Asunto(s)
17-Hidroxiesteroide Deshidrogenasas/deficiencia , Trastorno del Desarrollo Sexual 46,XY/genética , Adolescente , Pueblo Asiatico/genética , Niño , Femenino , Humanos , Mutación
12.
J Colloid Interface Sci ; 298(2): 765-8, 2006 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-16458915

RESUMEN

A simple method of the reduction of AgNO3 by copper foil in aqueous medium was used to prepare silver dendrites, which can be used as a novel good reproducible surface enhanced Raman scattering (SERS) active substrate. The SERS spectra of 4-pyridinethiol on this novel substrate reflected the different SERS activities on the minuteness and strong Ag dendrites. The electromagnetic coupling enhancement and chemical enhancement mechanisms are used to explain the SERS effect.

13.
Artículo en Inglés | MEDLINE | ID: mdl-16458579

RESUMEN

We describe a simple method to synthesize triangular silver nanoparticles by photoreducing the silver ions by citrate. A noteworthy difference of the present method as compared with the previous photo-induced methods is that good shape control over the nanoparticles can be realized in the absence of soft templates or polymer directing agents. The formation process of the silver nanoparticles was investigated by UV-vis spectroscopy and transmission electron microscopy (TEM). It was found that the concentration of reactant plays important role in the morphology control of produced silver nanoparticles. As one of the applications of these nanoparticles, they were used as surface-enhanced Raman scattering substrates and 1,4-bis[2-(4-pyridyl)ethenyl]-benzene (BVPP) was used as a Raman probe to evaluate the enhancement ability of the triangular silver nanoparticles.


Asunto(s)
Química/métodos , Nanoestructuras/química , Plata/química , Espectrometría Raman/métodos , Ácido Cítrico/química , Iones , Luz , Microscopía Electrónica de Transmisión , Radiación , Dispersión de Radiación , Sodio/farmacología
14.
Spectrochim Acta A Mol Biomol Spectrosc ; 64(1): 101-5, 2006 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-16095953

RESUMEN

Ag/CdTe nanocomposite was prepared via self-organization process by electrostatic interaction between positively charged CdTe quantum dots and negatively charged Ag nanoparticles and examined with respect to their optical properties. The positively charged CdTe quantum dots and negatively charged Ag nanoparticles were synthesized separately by modifying nanoparticles surface with cationic and anionic thiol compounds, respectively. The result showed that the mixing ratio of Ag nanoparticles to CdTe quantum dots is an important parameter for controlling resulting composites. The resulting solution is optically transparent if one component is in excess. Photoluminescence of CdTe quantum dots undergoes considerably quenching if CdTe nanocrystals are in excess and SERS spectra of BVPP absorbed on Ag colloid became stronger if Ag nanoparticles are in excess. Nevertheless, while the ratio is approximately 1, micrometer-sized solid composite is obtained with the elapse of 1h after mixing. SERS spectra for solid composite only exhibit the signals of the CdS nanocrystal which reflected that prolonged refluxing during the synthesis leads to a partial hydrolysis of the thiols and to the incorporation of the sulfur from the thiol molecules into the the growing nanoparticles to form mixed CdTe(S) nanocrystal, similar to CdTe/CdS core/shell structure. From the results, we conclude that optical properties of Ag/CdTe are dependent on the mixing ratio of both nanoparticles.


Asunto(s)
Compuestos de Cadmio/química , Nanoestructuras/química , Puntos Cuánticos , Plata/química , Telurio/química , Cristalización , Óptica y Fotónica , Análisis Espectral , Electricidad Estática
15.
PLoS One ; 11(9): e0163692, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27668866

RESUMEN

Soybean oil content is one of main quality traits. In this study, we used the multifactor dimensionality reduction (MDR) method and a soybean high-density genetic map including 5,308 markers to identify stable single nucleotide polymorphism (SNP)-SNP interactions controlling oil content in soybean across 23 environments. In total, 36,442,756 SNP-SNP interaction pairs were detected, 1865 of all interaction pairs associated with soybean oil content were identified under multiple environments by the Bonferroni correction with p <3.55×10-11. Two and 1863 SNP-SNP interaction pairs detected stable across 12 and 11 environments, respectively, which account around 50% of total environments. Epistasis values and contribution rates of stable interaction (the SNP interaction pairs were detected in more than 2 environments) pairs were detected by the two way ANOVA test, the available interaction pairs were ranged 0.01 to 0.89 and from 0.01 to 0.85, respectively. Some of one side of the interaction pairs were identified with previously research as a major QTL without epistasis effects. The results of this study provide insights into the genetic architecture of soybean oil content and can serve as a basis for marker-assisted selection breeding.

16.
J Colloid Interface Sci ; 292(2): 455-61, 2005 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-16061242

RESUMEN

A new SERS-active silver film prepared by directly depositing silver nanoparticles on glass is reported. The spontaneous reduction of Ag+ ions in N,N-dimethylformamide (DMF) (in the absence of a protecting agent) leads to the deposition of silver nanoparticles on clean glass surfaces in contact with the solution. The observed optical micrographs and AFM images show that the arrangement of the nanoparticles is inhomogeneous and the particles appear to be closely packed. These films are shown to be excellent substrates for SERS measurements, demonstrating significant enhancement, good stability, and trace detection capability. The SERS enhancement of the silver films with different deposition times was compared and found that the 8-h film gives the largest enhancement ability with an enhancement factor estimated at about 10(9). It is also found that the silver films stored for 80 days in air show no significant degradation in their sensitivity.


Asunto(s)
Formamidas/química , Membranas Artificiales , Plata/química , Espectrometría Raman/métodos , Dimetilformamida , Nanopartículas/química , Oxidación-Reducción , Tamaño de la Partícula , Sensibilidad y Especificidad , Propiedades de Superficie
17.
Appl Spectrosc ; 58(1): 26-32, 2004 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-14727717

RESUMEN

A new surface-enhanced Raman scattering (SERS) active substrate has been developed based on our previous study. Small silver nanoparticles on a quartz slide can be enlarged by using a mixture of commercially available reagents called Silver Enhancer and Initiator. The optical properties and characteristics of the new substrate have been investigated by ultraviolet-visible (UV-Vis) spectroscopy and atomic force microscopy (AFM). The results indicate that the small silver nanoparticles grow and some silver aggregates emerge on the quartz slide after the slide is immersed into the Silver Enhancer and Initiator Mixture (SEIM). The average diameter of the silver nanoparticles on the substrate becomes approximately double after the immersion into SEIM for 20 s. 1,4-bis[2-(4-pyridyl)ethenyl]-benzene (BPENB) was used as a Raman probe to evaluate the enhancement ability of the new silver substrate. It has been found that the SERS intensity can be increased about 10 times by using the substrate treated by SEIM compared with that without being treated by SEIM. Interestingly enough, the SERS enhancement increases with time. This may be due to the reorganization of silver nanoparticles on the quartz surface. The new substrate can remain active for more than 90 days. The adsorption mode of BPENB on the new substrate and the dependence of the BPENB configurations on the concentration of BPENB in methanol solution have also been investigated by SERS or UV-Vis spectroscopy. The SERS spectra of a self-assembled monolayer (SAM) BPENB film adsorbed on a silver substrate treated by SEIM show that BPENB molecules are chemically absorbed through the Ag-N bond. Consequently, a nearly perpendicular orientation of BPENB on the silver surface is proposed. The SERS spectra of BPENB SAMs on the new substrates fabricated from methanol solutions with different concentrations are compared. The concentration dependence of the SERS spectra reveals that the BPENB molecules are adsorbed on the silver film as monomers when the film is prepared from the solution with a lower concentration (<4 x 10(-6) M) and as aggregates when it is prepared from the solution with a higher concentration (>1 x 10(-5) M).

18.
Appl Spectrosc ; 58(3): 287-91, 2004 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-15035708

RESUMEN

A self-assembled monolayer (SAM) film of 5,10,15,20-tetra-(para-chlorophenyl)-porphyrin terbium (or lutetium) hydroxy compound (TbOH/LuOH) fabricated on a silver substrate premodified with a SAM of 4-mercaptopyridine (PySH) was studied by ultraviolet-visible (UV-Vis) spectroscopy and surface-enhanced Raman scattering (SERS) spectroscopy. PySH can modify the substrate and deliver its pyridyl group pointing out from the silver surface. Thus, we can investigate the effects of the central metals of the metalloporphyrins in the formation of the composite films. For the TbOH-PySH composite film, a new absorption band arising from TbOH appears at 425 nm, and a band at 512 nm due to the PySH-modified silver substrate shifts to a longer wavelength (538 nm). The results suggest that TbOH is successfully assembled on the top of PySH-modified silver film and that there is an interaction between TbOH and PySH in the film. The frequency shifts and relative intensity changes of bands due to PySH in the SERS spectra imply the coordination of the pyridyl group on Tb in the SAM. As for the LuOH-PySH composite film, its SERS spectrum shows bands arising from both the LuOH and PySH moieties, indicating that LuOH is assembled on the PySH-modified silver film. Furthermore, a band at 1221 cm(-1) due to the in-plane C-H bending mode of PySH disappears, implying that the pyridyl moiety of PySH becomes more parallel to the silver surface upon the formation of the LuOH-PySH composite film. Additionally, an absorption band at 515 nm shifts to a longer wavelength (541 nm) and becomes broad upon the formation of the composite film, suggesting an interaction between LuOH and PySH in the film. By comparing the spectral changes between the two self-assembled composite films, we find that the central metal is crucial in the formation of the composite films. The structure and orientation of the composite films depend on the central metal of the metalloporphyrin compounds.

19.
J Colloid Interface Sci ; 274(1): 9-15, 2004 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-15120272

RESUMEN

We investigated the fabrication of self-assembled monolayers of 5,10,15,20-tetra-(p-chlorophenyl)-porphyrin metal hydroxyl compounds (MOH; M=Gd, Tb, Er, Lu) on amino-terminated silanized quartz surfaces using ultraviolet-visible (UV-vis) and X-ray photoelectron spectroscopy (XPS). The orientation of MOH molecules in the films, the kinetics of the adsorption of MOH from a chloroform solution on an amino-terminated quartz substrate, and the stability of the metalloporphyrin films under natural light, UV light, and acidic and basic conditions were studied by UV-vis spectroscopy. The results indicate that the central metal is crucial in the formation of self-assembled porphyrin films and that the stability of the MOH SAMs also depends on the central metal. Under natural and UV light irradiation conditions, the stability of the MOH SAMs depends on the strength of the M-N bonds between the central metal and pyrrole nitrogens or between the central metal and the axial ligand. In the acidic conditions, the UV-vis spectra of the MOH SAMs show decreases in the absorbance and blue shifts. These spectral changes lead us to suggest that the four M-N bonds between the central metal and the pyrrole nitrogens of the porphyrins are cleaved and the resulted porphyrins are protonated under acidic conditions. Thus, it is likely that the protonated porphyrins and MOH form pi-pi complexes with a parallel stacking of the macrocycles through the electrostatic attractive interaction in the SAMs, resulting in the blue shifts of the Soret bands of the SAMs.

20.
J Pharm Sci ; 102(7): 2341-8, 2013 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-23657983

RESUMEN

Developing coatings on implant surface as drug carriers can reduce organ toxicity and effectively deliver drug locally to the target compared with the oral approach. Titanium dioxide (TiO2) nanotube has great potential for this application for widely used Ti implants because of its high surface area, ability to promote bone growth, and biocompatibility. However, there are two issues needed to be solved before further advancing TiO2 nanotubes technology as drug carriers: uncontrolled drug release and poor mechanical properties. In this study, a drug carrier using a composite of biodegradable polymer/TiO2 nanotubes is engineered. Ibuprofen is selected as a concept drug because it is a commonly used anti-inflammatory, fever, and pain-reducing drug. In addition, ibuprofen has a very short plasma half-life of only 1-3 h. A simple characterization method is developed to investigate the infiltration of polymer into TiO2 nanotubes. Good infiltration was observed of polymer into TiO2 nanotubes. The synthesized drug carrier demonstrated much better sustained drug release profiles for ibuprofen of 5 days (low-molecular-weight polymer) and 9 days (high-molecular-weight polymer) compared with 30 min of pure TiO2 nanotubes. The drug carrier also exhibited much improved mechanical strength and flexibility compared with pure TiO2 nanotubes.


Asunto(s)
Antiinflamatorios no Esteroideos/administración & dosificación , Preparaciones de Acción Retardada/química , Ibuprofeno/administración & dosificación , Ácido Láctico/química , Nanotubos/química , Ácido Poliglicólico/química , Titanio/química , Nanotubos/ultraestructura , Copolímero de Ácido Poliláctico-Ácido Poliglicólico , Prótesis e Implantes , Resistencia a la Tracción
SELECCIÓN DE REFERENCIAS
Detalles de la búsqueda