Interaction between fluorescent proteins and CdSe/ZnS nanocrystals

Foram utilizadas proteínas da famÌlia das GFPs e nanocristais fluorescentes de CdSe/ZnS para caracterização da interação e verificação de transferência de energia por ressonância (FRET) entre estes compostos. Formou-se dois pares doador-receptor onde ora uma proteína figurava como doadora, ora um nanocristal ocupava este papel. Verificou-se que, em ambos os casos, o doador sofre supressão da fluorescência após a formação de complexo com o receptor, complexo este motivado por interação eletrostática e dependente de pH. Foi possível comprovar, através da observação de emissão sensitizada e redução da anisotropia, que entre o par formado por nanocristal com emissão no verde e proteína HcRed1 como receptora, de fato ocorre FRET. As distâncias aparentes entre doador e receptor foram determinadas a partir da eficiência da supressão da fluorescência do doador e da distância de Förster. As distâncias assim obtidas são compatíveis com as dimensões das proteínas e dos nanocristaisProteins belonging to the GFP family were used to characterize their interaction with fluorescent CdSe/ZnS nanocrystals and to verify the occurrence of resonance energy transfer (FRET) among these elements. Two donor-acceptor pairs were established, one having a protein as donor and the other having a nanocrystal as donor. In both cases the donor suffers quenching of its fluorescence after the formation of a complex with the acceptor. The complex formation is dependent on pH and is due to electrostatic interaction. It was possible to prove the occurrence of FRET between CdSe/ZnS nanocrystals emitting green fluorescence as donors and the protein HcRed1 as acceptor, through the detection of sensitized emission and anisotropy reduction. Apparent donor-acceptor distances were determined from efficiency measurements and Förster distances. The obtained distances agreed with the protein and nanocrystal dimension

Chikungunya Virus E2 Structural Protein B-Cell Epitopes Analysis

The Togaviridae family comprises a large and diverse group of viruses responsible for recurrent outbreaks in humans. Within this family, the Chikungunya virus (CHIKV) is an important Alphavirus in terms of morbidity, mortality, and economic impact on humans in different regions of the world. The objective of this study was to perform an IgG epitope recognition of the CHIKV’s structural proteins E2 and E3 using linear synthetic peptides recognized by serum from patients in the convalescence phase of infection. The serum samples used were collected in the state of Sergipe, Brazil in 2016. Based on the results obtained using immunoinformatic predictions, synthetic B-cell peptides corresponding to the epitopes of structural proteins E2 and E3 of the CHIKV were analyzed by the indirect peptide ELISA technique. Protein E2 was the main target of the immune response, and three conserved peptides, corresponding to peptides P3 and P4 located at Domain A and P5 at the end of Domain B, were identified. The peptides P4 and P5 were the most reactive and specific among the 11 epitopes analyzed and showed potential for use in serological diagnostic trials and development and/or improvement of the Chikungunya virus diagnosis and vaccine design

A statistical evaluation of the field emission for copper oxide nanostructures

A statistical data analysis methodology was developed to evaluate the field emission properties of many samples of copper oxide nanostructured field emitters. This analysis was largely done in terms of Seppen-Katamuki (SK) charts, field strength and emission current. Some physical and mathematical models were derived to describe the effect of small electric field perturbations in the Fowler-Nordheim (F-N) equation, and then to explain the trend of the data represented in the SK charts. The field enhancement factor and the emission area parameters showed to be very sensitive to variations in the electric field for most of the samples. We have found that the anode-cathode distance is critical in the field emission characterization of samples having a non-rigid nanostructure. (C) 2007 Elsevier B.V. All rights reserved