Poly(dopamine) assisted deposition of adherent PPy film on Ti substrate

This study aims to address an issue to a subject that is still less present in literature: the adherence of polypyrrole (PPy) films on bioinert substrate. The poly(dopamine) (PDA) assisted deposition of PPy film on titanium substrate was performed in two steps. The chemical self-polymerization of dopamine was performed as a preliminary step from dopamine in Tris buffer solution on titanium substrate. Then, the resulted poly(dopamine) layer consisting of anchors with strong interactions with Ti surface was a new suitable substrate for polypyrrole film electrochemical deposition. The new PDA–PPy films were characterized in terms of interest properties for the desired biomedical applications: adherence, electrochemical stability of PDA–PPy film, wettability, topography, morphology and antibacterial effect. The poly(dopamine) assisted deposition of PPy film has been shown to be a facile and efficient route to improve the adhesion of PPy film on titanium maintaining or improving the properties of polymeric film.     

Assessment of the Antioxidant Activity of Catechin in Nutraceuticals: Comparison between a Newly Developed Electrochemical Method and Spectrophotometric Methods

The analysis of antioxidants in different foodstuffs has become an active area of research, which has led to many recently developed antioxidant assays. Many antioxidants exhibit inherent electroactivity, and, therefore, the use of electrochemical methods could be a viable approach for evaluating the overall antioxidant activity of a matrix of nutraceuticals without the need for adding reactive species. Green tea is believed to be a healthy beverage due to a number of therapeutic benefits. Catechin, one of its constituents, is an important antioxidant and possesses free radical scavenging abilities. The present paper describes the electrochemical properties of three screen-printed electrodes (SPEs), the first one based on carbon nanotubes (CNTs), the second one based on gold nanoparticles (GNPs) and the third one based on carbon nanotubes and gold nanoparticles (CNTs-GNPs). All three electrodes were modified with the laccase (Lac) enzyme, using glutaraldehyde as a cross-linking agent between the amino groups on the laccase and aldehyde groups of the reticulation agent. As this enzyme is a thermostable catalyst, the performance of the biosensors has been greatly improved. Electro-oxidative properties of catechin were investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV), and these demonstrated that the association of CNTs with GNPs significantly improved the sensitivity and selectivity of the biosensor. The corresponding limit of detection (LOD) was estimated to be 5.6 × 10⁻⁸ M catechin at the CNT-Lac/SPE, 1.3 × 10⁻⁷ M at the GNP-Lac/SPE and 4.9 × 10⁻⁸ M at the CNT-GNP-Lac/SPE. The biosensors were subjected to nutraceutical formulations containing green tea in order to study their catechin content, using CNT-GNP-Lac/SPE, through DPV. Using a paired t-test, the catechin content estimated was in agreement with the manufacturer’s specification. In addition, the relationship between the CNT-GNP-Lac/SPE response at a specific potential and the antioxidant activity of nutraceuticals, as determined by conventional spectrophotometric methods (DPPH, galvinoxyl and ABTS), is discussed in the context of developing a fast biosensor for the relative antioxidant activity quantification.     

硼酸-硫酸阳极氧化2A97Al-Cu-Li合金在热带海洋大气环境中的初期腐蚀机理

采用光学显微镜、扫描电镜、能谱仪、电化学阻抗谱测试结合超薄切片,分析阳极氧化2A97Al-Cu-Li合金在大气腐蚀前后的微观形貌、化学成分及电化学性能。结果表明:在不同温度利用含有硼酸-硫酸或酒石酸-硫酸组合的电解液生长膜层时,硼酸添加和较高温度允许较大的电流密度通过,使膜生长加速;对于不同电解液,孔的几何构形和结构相似;硼酸-硫酸阳极氧化试样在热带海洋大气环境中暴露1个月后,出现主要由O,Al,Cl,Cu组成的分散性黑色锈斑,表面产生白色沉淀;随着户外暴露时间的延长,合金发生严重的点蚀并深入合金内部,腐蚀的扩展与θ相粒子有关。     

Molecular Mapping of Antifungal Mechanisms Accessing Biomaterials and New Agents to Target Oral Candidiasis

Oral candidiasis has a high rate of development, especially in immunocompromised patients. Immunosuppressive and cytotoxic therapies in hospitalized HIV and cancer patients are known to induce the poor management of adverse reactions, where local and systemic candidiasis become highly resistant to conventional antifungal therapy. The development of oral candidiasis is triggered by several mechanisms that determine oral epithelium imbalances, resulting in poor local defense and a delayed immune system response. As a result, pathogenic fungi colonies disseminate and form resistant biofilms, promoting serious challenges in initiating a proper therapeutic protocol. Hence, this study of the literature aimed to discuss possibilities and new trends through antifungal therapy for buccal drug administration. A large number of studies explored the antifungal activity of new agents or synergic components that may enhance the effect of classic drugs. It was of significant interest to find connections between smart biomaterials and their activity, to find molecular responses and mechanisms that can conquer the multidrug resistance of fungi strains, and to transpose them into a molecular map. Overall, attention is focused on the nanocolloids domain, nanoparticles, nanocomposite synthesis, and the design of polymeric platforms to satisfy sustained antifungal activity and high biocompatibility with the oral mucosa.     

Relationship of working alliance to mutual and unilateral termination.

Examined the relationship between strength of working alliance after the 3rd session and unilateral client termination. Participants were 4 PhD psychologists and 6 practicum trainees and their 103 college student clients. Both members of 91 counseling dyads (88%) completed the short version of the Working Alliance Inventory (T. J. Tracey and A. M. Kokotovic, 1989) after the 3rd counseling session. Counselor ratings of working alliance were positively associated with mutual termination. Client working alliance ratings did not relate to termination type. It was suggested that counselors focus directly on strengthening weak alliances with clients to prevent client unilateral termination. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of mechanical treatments on orientation behavior and spectral properties of azoderivative dyes incorporated in poly(vinyl alcohol) films

Various azoderivative dyes were incorporated in uncolored poly(vinyl alcohol) (PVOH). One type of film was obtained by drying the layer of solution cast on glass plate. The other type was obtained by rubbing the PVOH layer before complete drying. Linear birefringence and dichroism of dyed polymer films were investigated as a function of stretching degree. An increase in the linear birefringence was found with increasing stretching degree for both uncolored and colored films. Dichroism of the PVOH films depends on the dye chemical structure and also on the stretching degree of both non-rubbed and rubbed and dyed PVOH samples. Molecular modeling was used to examine interactions occurring between PVOH and the embedded dye molecule. These stretching degree dependencies were approximated mathematically, which was used to describe the behavior of some components of interference filters.     

Phenolic and Anthocyanin Profile of Valea Calugareasca Red Wines by HPLC-PDA-MS and MALDI-TOF Analysis

The quality of red wines is given by phenolic compounds and anthocyanins and is associated with colour, taste and therapeutic effects on human health. This work aims to provide a detailed profile of phenolic compounds and anthocyanins that are found in five red wine samples from Dealu Mare-Valea Calugareasca region. The phenolic and anthocyanin profiles of the red wine samples were determined by high-performance liquid chromatography-photodiode array-mass spectrometry and matrix-assisted laser desorption/ionisation–time of flight, respectively. The results obtained showed that Feteasca Neagra had the highest content of phenolic compounds followed by Pinot Noir while the preponderant compound was gallic acid. Amongst anthocyanins, malvidin was found to be the major compound and the highest anthocyanin content was found also for Feteasca Neagra wine. A simple high-performance liquid chromatography-photodiode array-mass spectrometry method was developed, optimised and applied for the quantification of phenolic compounds in red wine samples from Dealu Mare-Valea Calugareasca region. In the same time, a rapid matrix-assisted laser desorption/ionisation–time of flight method that does not need sample preparation was applied for the identification of anthocyanins. Moreover, the phenolic and anthocyanin composition of red wines from Dealu Mare-Valea Calugareasca region is reported for the first time. The phenolic and anthocyanin profile determination will be beneficial for the Romanian winemakers to produce high-quality red wines.