The electrochemical behavior of some polybenzofulvene derivatives bearing bithiophene (BT) or terthiophene (TT) side chains was investigated by cyclic voltammetry. Very interestingly, the presence of ...unsubstituted terminal thiophene moieties allowed poly-6-BT-
BF3k
and poly-6-TT-
BF3k
to be cross-linked by electrochemical procedures. Conductive films were obtained by electrodeposition from solutions of these polymers onto electrode surfaces through the formation of covalent cross-linking due to dimerization (
i.e.
electrochemical oxidation) of the BT or TT side chains. The films showed electrochromic features and switched from yellow-orange (neutral) to green (positively charged) by switching the potential, and were stable to tenths of cycles, without degradation in the wet state in the electrolyte solution. Finally, the thin film obtained by electrodeposition of poly-6-TT-
BF3k
on a indium tin oxide (ITO) glass substrate showed in the neutral state a significantly red-shifted photoluminescence (PL) emission (∼40 nm red-shifted with respect to that of the corresponding film obtained by casting procedures), which was consistent with the presence of more conjugated moieties produced by the oxidative dimerization of the TT side chains. The innovative architecture and the easy preparation could lead to a broad range of applications in optoelectronics and bioelectronics for these cross-linked hybrid materials based on π-stacked polybenzofulvene backbones bearing oligothiophene side chains.
The electrochemical behavior of some polybenzofulvene derivatives bearing bithiophene (BT) or terthiophene (TT) side chains was investigated by cyclic voltammetry and cross-linked materials were obtained by dimerization of the BT or TT side chains.
Cyclooxygenase-2 (COX-2) is involved in the inflammatory response, and its recurrent overexpression in cancers as well as in neurodegenerative disorders has made it an important target for therapy. ...For this reason, noninvasive imaging of COX-2 expression may represent an important diagnostic tool. In this work, a COX-2 inhibitor analogue, VA426 1-(4-fluorophenyl)-3-(2-methoxyethyl)-2-methyl-5-(4-(methylsulfonil)phenyl)-1
-pyrrole, was synthesized and radiolabelled with the
C radioisotope. The ex vivo biodistribution profile of
C-VA426 was evaluated in the brain and periphery of healthy rats and mice and in brain and periphery of inflammation models, based on the administration of LPS.
C-VA426 synthesis with the
BuOK base showed optimal radiochemical yield (15 ± 2%) based on triflate activity, molar activity (range 37-148 GBq/
mol), and radiochemical purity (>95%). Ex vivo biodistribution studies showed a fast uptake of radioactivity but a rapid washout, except in regions expressing COX-2 (lungs, liver, and kidney) both in rats and in mice, with maximum values at 30 and 10 minutes p.i., respectively. LPS administration did not show significant effect on radioactivity accumulation. Celecoxib competition experiments performed in rats and mice treated with LPS produced a general target unrelated reduction of radioactivity concentration in all peripheral tissues and brain areas examined. Finally, in agreement with the negative results obtained from biodistribution experiments, radiometabolites analysis revealed that
C-VA426 is highly unstable in vivo. This study indicates that the compound
C-VA426 is not currently suitable to be used as radiopharmaceutical for PET imaging. This family of compounds needs further implementation in order to improve in vivo stability.
A small series of Morita-Baylis-Hillman adduct (MBHA) derivatives was synthesized and made to react with imidazole,
N
-acetylhistidine, and
N
-acetylhexahistidine as models of poly-histidine ...derivatives. Intriguingly, the reaction of MBHA derivatives
1a
and
b
with imidazole in acetonitrile-phosphate buffered saline (PBS) gave the imidazolium salt biadducts
3a
and
b
as the main reaction products. These results were confirmed by experiments performed with
N
-acetylhistidine and
1b
and suggested the possible occurrence of these structures in the products of poly-histidine labeling with MBHA derivatives
1a
and
b
. These compounds were then transformed into the corresponding water-soluble derivatives
1c-e
by introducing oligo(ethylene glycol) chains and their reactivity was evaluated in preliminary experiments with imidazole and then with
N
-acetylhexahistidine in PBS. The structure of polymeric materials
Ac-His-6-MBHA-1d
and
Ac-His-6-MBHA-1e
obtained using ten-fold excesses of compounds
1d
and
e
was investigated using mass spectrometry, NMR spectroscopy, and photophysical studies, which suggested the presence of biadduct residues in both polymeric materials. These results provide the basis for the preparation of fishbone-like polymer brushes, the characterization of their properties, and the exploration of their potential applications in different fields of science such as
in vivo
fluorogenic labeling, fluorescence microscopy, protein PEGylation, up to the production of smart materials and biosensors.
A small series of Morita-Baylis-Hillman derivatives was synthesized and made to react with
N
-acetylhexahistidine to give polymeric materials characterized by the presence of biadduct residues.
In order to develop a technology platform based on two natural compounds from biorenewable resources, a short series of hyaluronan (
HA
) copolymers grafted with propargylated ferulic acid (
HA-FA-Pg
...) were designed and synthesized to show different grafting degree values and their optical properties were characterized in comparison with reference compounds containing the same ferulate fluorophore. Interestingly, these studies revealed that the ferulate fluorophore was quite sensitive to the restriction of intramolecular motion and its introduction into the rigid
HA
backbone, as in
HA-FA-Pg
graft copolymers, led to higher photoluminescence quantum yield values than those obtained with the isolated fluorophore. Thus, the propargyl groups of
HA-FA-Pg
derivatives were exploited in the coupling with oleic acid through a biocompatible nona(ethylene glycol) spacer as an example of the possible applications of this technology platform. The resulting
HA-FA-NEG-OA
materials showed self-assembling capabilities in aqueous environment. Furthermore,
HA-FA-NEG-OA
derivatives have been shown to interact with phospholipid bilayers both in liposomes and living cells, retaining their fluorogenic properties and showing a high degree of cytocompatibility and for this reason they were proposed as potential biocompatible self-assembled aggregates forming new materials for biomedical applications.
A new technology platform has been developed with hyaluronan playing the role of the macromolecular carrier and ferulate the central role of natural small molecule fluorogenic clickable linker.
PDF