RESUMO
This study presents the synthesis and characterization of phenazinium dyes with absorption ranging from red to far-red, as well as emission extending into the far-red to near-infrared (NIR) region. The procedure involves the post-functionalization of a triamino-phenazinium that was recently reported as a theranostic agent. The introduction of electron-withdrawing moieties is accomplished through acylation or aromatic nucleophilic substitution. For one of the obtained products, a further substitution step could be achieved with primary amines to tune the electron density of the phenazinium core. The isolated dyes exhibit promising features that hold potential for future applications as biological markers or therapeutic agents.
RESUMO
The straightforward access to N- or C-substituted dinitro-tetraamino-phenazines (P1-P5) is enabled in oxidative conditions via formation of two intermolecular C-N bonds from accessible 5-nitrobenzene-1,2,4-triamine precursors. The photophysical studies revealed green absorbing and orange-red emitting dyes, with enhanced fluorescence in the solid state. Further reduction of the nitro functions led to the isolation of a benzoquinonediimine-fused quinoxaline (P6), which undergoes diprotonation to form a dicationic coupled trimethine dye absorbing beyond 800 nm.
RESUMO
The aim of this paper was to present a parallel investigation of the poly(dopamine) (DP) and nitrodopamine (NDP) structures deposited on titanium surface (Ti) and titanium oxide nanotubes (NT-TiO2/Ti) and to highlight their advantages and drawbacks to serve as an intermediary layer for bone regeneration applications. This study outlines some hypotheses regarding the manner in which these compounds are able to form a stable film that could serve as bioadhesive. The paper is also a study of structuring and evolution of film architecture for two coatings, polydopamine and nitrodopamine in terms of surface structure, stability, wettability, morphology, adhesion and ability to protect the titanium surface. All investigations are based on the data provided by surface characterization techniques: SEM, RAMAN, XRD, XPS, wettability and flexural strength. The impact of polydopamine and nitrodopamine coatings on the biocompatibility of titanium nanotubes was investigated in vitro. Cell morphology, viability, proliferation and pre-osteoblast differentiation were examined in detail. It was highlighted that both DP and NDP functionalized TiO2 nanotubes display good cell response in terms of cell spreading, formation of focal adhesions, cell viability and proliferation, suggesting their suitability for applications in bone regeneration field. However, NDP coated TiO2 nanotubes demonstrated an enhanced osteogenic potential compared to DP coated substrates.