Melanins are promising materials for organic bioelectronics devices like transistors, sensors and batteries. In this study, the chemical structural changes of melanin synthesized, by the auto oxidation of L-DOPA, are analyzed for a new synthetic procedure that uses oxygen under pressure (4 to 8 atm). TEM, DLS, FTIR, NMR and XPS are use to characterize the material. Under oxygen pressure, melanin synthesis is accelerated, the polymer obtained is found to have structural differences most notably a higher number of carbonyl groups and different surface charges compared to conventional synthetic melanin. As a consequence it has higher homogeneity and it is soluble in water. To explain these findings a reaction mechanism is proposed based on current melanogenesis models.Keywords: Melanin, oxygen pressure, solubility, accelerated synthesis. E-mail address: joaovp281@gmail.comThis article is protected by copyright. All rights reserved.This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/pi.5185 Accepted Articleexample, thin films of synthetic melanin with good adherence and controllable thickness were made using layer-by-layer technique. It has also been reported that it is possible to obtain melanin films from electrochemical deposition methods, [8] An alternative to obtain good quality films is to modify the melanin structure preserving its main properties, but increasing its solubility or changing its aggregation state. The advantage of this approach is that all processing techniques used up to now for organic semiconducting polymers device production would be available for melanin. In addition, many routine advanced techniques dedicated to thin film or solution characterization could be used. In the last 15 years soluble melanin derivatives were synthesized using different functionalized groups. [14][15][16][17][18] In this study, we propose an alternative synthetic approach for a soluble melanin without any exotic functionalization using molecular oxygen under pressure. Molecular oxygen is considered an ideal oxidant in the context of "green chemistry"; it has low cost, is abundant and environmentally friendly, having thus academic and industrial interest. In addition the synthesis is found to be faster under oxygen pressure. EXPERIMENTALAll the commercially available chemicals were purchased from Acros or Sigma-Aldrich and were used without further purification. In what concerns reproducibility, more than 3 different syntheses were performed and similar optical and structural properties were obtained. Melanin synthesisThe synthesis of melanin was carried out using well-known procedures briefly described. [19] Initially 0.3 g of L-3,4-dihydroxyphenylalanine (L-DOPA) was dissolved in 60 mL of deionized water (Milli-Q), next 0.4 mL of ammonium hydroxide (NH 4 OH) is added, ...

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BackgroundThe application and better understanding of traditional and new breast tumor biomarkers and prognostic factors are increasing due to the fact that they are able to identify individuals at high risk of breast cancer, who may benefit from preventive interventions. Also, biomarkers can make possible for physicians to design an individualized treatment for each patient. Previous studies showed that trace elements (TEs) determined by X-Ray Fluorescence (XRF) techniques are found in significantly higher concentrations in neoplastic breast tissues (malignant and benign) when compared with normal tissues. The aim of this work was to evaluate the potential of TEs, determined by the use of the Energy Dispersive X-Ray Fluorescence (EDXRF) technique, as biomarkers and prognostic factors in breast cancer.MethodsBy using EDXRF, we determined Ca, Fe, Cu, and Zn trace elements concentrations in 106 samples of normal and breast cancer tissues. Cut-off values for each TE were determined through Receiver Operating Characteristic (ROC) analysis from the TEs distributions. These values were used to set the positive or negative expression. This expression was subsequently correlated with clinical prognostic factors through Fisher’s exact test and chi-square test. Kaplan Meier survival curves were also evaluated to assess the effect of the expression of TEs in the overall patient survival.ResultsConcentrations of TEs are higher in neoplastic tissues (malignant and benign) when compared with normal tissues. Results from ROC analysis showed that TEs can be considered a tumor biomarker because, after establishing a cut-off value, it was possible to classify different tissues as normal or neoplastic, as well as different types of cancer.The expression of TEs was found statistically correlated with age and menstrual status. The survival curves estimated by the Kaplan-Meier method showed that patients with positive expression for Cu presented a poor overall survival (p < 0.001).ConclusionsThis study suggests that TEs expression has a great potential of application as a tumor biomarker, once it was revealed to be an effective tool to distinguish different types of breast tissues and to identify the difference between malignant and benign tumors. The expressions of all TEs were found statistically correlated with well-known prognostic factors for breast cancer. The element copper also showed statistical correlation with overall survival.

The development of pH sensors is of great interest due to its extensive application in several areas such as industrial processes, biochemistry and particularly medical diagnostics. In this study, the pH sensing properties of an extended gate field effect transistor (EGFET) based on melanin thin films as active layer are investigated and the physical mechanisms related to the device operation are discussed. Thin films were produced from different melanin precursors on indium tin oxide (ITO) and gold substrates and were investigated by Atomic Force Microscopy and Electrochemical Impedance Spectroscopy. Experiments were performed in the pH range from 2 to 12. EGFETs with melanin deposited on ITO and on gold substrates showed sensitivities ranging from 31.3 mV/pH to 48.9 mV/pH, depending on the melanin precursor and the substrate used. The pH detection is associated with specific binding sites in its structure, hydroxyl groups and quinone imine.

Biocompatibility tests were performed for melanin synthesized in water (W‐Mel) and dimethylsulfoxide (D‐Mel) aiming to evaluate its potential for bioelectronics application. In vitro biocompatibility of melanin was assessed using crystal violet assays with fibroblast cells (NIH3T3) cultured with W‐Mel and D‐Mel extracts in various dilutions. The results show that a high concentration of melanin kills the cells. However, after periods of 48 h incubation, cell viability is significantly favored after treatment with D‐Mel at low concentrations (1:16, 1:32 and 1:64), as opposed to treatment with W‐Mel extracts. Cellular adhesion tests show that fibroblast cells adhere to melanin thin films. These results show that D‐Mel may be an interesting material for application in bioelectronic devices targeted for implants. © 2016 Society of Chemical Industry

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It is estimated that multiple sclerosis (MS) affects 35,000 Brazilians and 2.5 million individuals worldwide. Many studies have suggested a possible role of metallic elements in the etiology of MS, but their concentration in the blood of MS patients is nonetheless little investigated in Brazil. In this work, these elements were studied through inductively coupled plasma Mass Spectrometry (icp-MS), whose analysis provides a tool to quantify the concentrations of metal elements in the blood samples of individuals with neurodegenerative disorders. This study aimed to compare the concentration of metallic elements in blood samples from patients with MS and healthy individuals. Blood was collected from 30 patients with multiple sclerosis and compared with the control group. Blood samples were digested in closed vessels using a microwave and ICP-MS was used to determine the concentrations of 12 metallic elements (

RESUMO A contaminação de água por metais pesados ainda é um grande risco de poluição. Diante deste cenário, processos adsortivos e diversos materiais adsorventes têm sido empregados para descontaminação. Dentre os materiais sintéticos e bioadsorventes empregados, os sintéticos são eficientes na remoção de metais em solução aquosa, contudo agregam alto custo comparados aos bioadsorventes. Os bioadsorventes são em geral provenientes de biomassa agroindustrial e vêm se destacando por serem abundantes, renováveis e com custo acessível para remediação de efluentes com metais pesados na forma ionizada. Dentre os bioadsorventes, a casca da banana reúne grupos funcionais capazes de adsorver íons de metais pesados em meio aquoso. Dessa forma, este trabalho descreve o método de preparação e caraterização da farinha da casca de banana (FCB) através das técnicas de Microscopia Eletrônica de Varredura (MEV), Espectroscopia Dispersiva em Energia de Raios X e Espectroscopia na Região do Infravermelho bem como estudos da capacidade adsortiva desse bioadsorvente para o íon Cu (II) em soluções aquosas. Os estudos de adsorção foram realizados através da avaliação das isotermas experimentais de adsorção em função do tempo de contato, variações do pH, temperatura e concentração de íon Cu (II) na solução pela técnica de batelada. As isotermas experimentais foram submetidas aos modelos matemáticos de isotermas de Langmuir e Freundlich. A capacidade máxima de adsorção alcançada pela FCB foi 15,1 mg de Cu (II) por grama de FCB, pH ajustado em 5 e tempo de saturação bastante rápido, em torno de 10 minutos. A isoterma de Langmuir foi o modelo que melhor se ajustou ao processo adsortivo de cobre (II) pela FCB e o preenchimento dos sítios ativos foi na faixa de 98,7%.