6 research outputs found
Superhydrophobic Copper Surfaces with Anticorrosion Properties Fabricated by Solventless CVD Methods
Due to continuous
miniaturization and increasing number of electrical
components in electronics, copper interconnections have become critical
for the design of 3D integrated circuits. However, corrosion attack
on the copper metal can affect the electronic performance of the material.
Superhydrophobic coatings are a commonly used strategy to prevent
this undesired effect. In this work, a solventless two-steps process
was developed to fabricate superhydrophobic copper surfaces using
chemical vapor deposition (CVD) methods. The superhydrophobic state
was achieved through the design of a hierarchical structure, combining
micro-/nanoscale domains. In the first step, O<sub>2</sub>- and Ar-plasma
etchings were performed on the copper substrate to generate microroughness.
Afterward, a conformal copolymer, 1<i>H</i>,1<i>H</i>,2<i>H</i>,2<i>H</i>-perfluorodecyl acrylate–ethylene
glycol diacrylate [p(PFDA-<i>co</i>-EGDA)], was deposited
on top of the metal via initiated CVD (iCVD) to lower the surface
energy of the surface. The copolymer topography exhibited a very characteristic
and unique nanoworm-like structure. The combination of the nanofeatures
of the polymer with the microroughness of the copper led to achievement
of the superhydrophobic state. AFM, SEM, and XPS were used to characterize
the evolution in topography and chemical composition during the CVD
processes. The modified copper showed water contact angles as high
as 163° and hysteresis as low as 1°. The coating withstood
exposure to aggressive media for extended periods of time. Tafel analysis
was used to compare the corrosion rates between bare and modified
copper. Results indicated that iCVD-coated copper corrodes 3 orders
of magnitude slower than untreated copper. The surface modification
process yielded repeatable and robust superhydrophobic coatings with
remarkable anticorrosion properties
Stable 5,5′-Substituted 2,2′-Bipyrroles: Building Blocks for Macrocyclic and Materials Chemistry
The preparation and
characterization of a family of stable 2,2′-bipyrroles
substituted at positions 5 and 5′ with thienyl, phenyl, TMS-ethynyl,
and vinyl groups is reported herein. The synthesis of these new bipyrroles
comprises three steps: formation of the corresponding 5,5′-unsubstituted
bipyrrole, bromination, and Stille or Suzuki coupling. The best results
in the coupling are obtained using the Stille reaction under microwave
irradiation. The new compounds have been fully characterized by UV–vis
absorption, fluorescence, and IR spectroscopies and cyclic voltammetry.
X-ray single-crystal analysis of four of the synthesized bipyrroles
indicates a trans coplanar geometry of the pyrrole rings. Furthermore,
the substituents at positions 5,5′ remain coplanar to the central
rings. This particular geometry extends the π-conjugation of
the systems, which is in agreement with a red-shifting observed for
the λ<sub>max</sub> of the substituted molecules compared to
the unsubstituted bipyrrole. All of these new compounds display a
moderate fluorescence. In contrast with unsubstituted bipyrroles,
these bipyrroles are endowed with a high chemical and thermal stability
and solubility in organic solvents
Quaterpyrroles as Building Blocks for the Synthesis of Expanded Porphyrins
A new
family of quaterpyrroles and their application as building
blocks for the synthesis of macrocycles is reported. The preparation
of these quaterpyrroles consisted of two synthetic steps: bromination
of 2,2′-bipyrroles bearing two electron-withdrawing groups
followed by Suzuki coupling with 1-(<i>tert</i>-butoxycarbonyl)pyrrole-2-boronic
acid. The resulting quaterpyrroles have been used to prepare an octaphyrin
and a substituted cyclo[8]pyrrole. Additionally, the synthesis of
a new macrocycle containing the quaterpyrrole and 2,5-di(1<i>H</i>-pyrrol-2-yl)thiophene moieties is presented
Quaterpyrroles as Building Blocks for the Synthesis of Expanded Porphyrins
A new
family of quaterpyrroles and their application as building
blocks for the synthesis of macrocycles is reported. The preparation
of these quaterpyrroles consisted of two synthetic steps: bromination
of 2,2′-bipyrroles bearing two electron-withdrawing groups
followed by Suzuki coupling with 1-(<i>tert</i>-butoxycarbonyl)pyrrole-2-boronic
acid. The resulting quaterpyrroles have been used to prepare an octaphyrin
and a substituted cyclo[8]pyrrole. Additionally, the synthesis of
a new macrocycle containing the quaterpyrrole and 2,5-di(1<i>H</i>-pyrrol-2-yl)thiophene moieties is presented
Design of a Nanostructured Active Surface against Gram-Positive and Gram-Negative Bacteria through Plasma Activation and in Situ Silver Reduction
Nowadays there is an increasing focus
for avoiding bacterial colonization
in a medical device after implantation. Bacterial infection associated
with prosthesis implantation, or even along the lifetime of the implanted
prosthesis, entails a serious problem, emphasized with immunocompromised
patients. This work shows a new methodology to create highly hydrophobic
micro-/nanostructured silver antibacterial surfaces against Gram-positive
and Gram-negative bacteria, using low-pressure plasma. PDMS (polydimethylsiloxane)
samples, typically used in tracheal prosthesis, are coated with PFM
(pentafluorophenyl methacrylate) through PECVD (plasma enhance chemical
vapor deposition) technique. PFM thin films offer highly reactive
ester groups that allow them to react preferably with amine bearing
molecules, such as amine sugar, to create controlled reductive surfaces
capable of reducing silver salts to a nanostructured metallic silver.
This micro-/nanostructured silver coating shows interesting antibacterial
properties combined with an antifouling behavior causing a reduction
of Gram-positive and Gram-negative bacteria viability. In addition,
these types of silver-coated samples show no apparent cytotoxicity
against COS-7 cells
Novel <sup>18</sup>F Labeling Strategy for Polyester-Based NPs for in Vivo PET-CT Imaging
Drug-loaded
nanocarriers and nanoparticulate systems used for drug
release require a careful in vivo evaluation in terms of physicochemical
and pharmacokinetic properties. Nuclear imaging techniques such as
positron emission tomography (PET) are ideal and noninvasive tools
to investigate the biodistribution and biological fate of the nanostructures,
but the incorporation of a positron emitter is required. Here we describe
a novel approach for the <sup>18</sup>F-radiolabeling of polyester-based
nanoparticles. Our approach relies on the preparation of the radiolabeled
active agent 4-[<sup>18</sup>F]fluorobenzyl-2-bromoacetamide ([<sup>18</sup>F]FBBA), which is subsequently coupled to block copolymers
under mild conditions. The labeled block copolymers are ultimately
incorporated as constituent elements of the NPs by using a modified
nano coprecipitation method. This strategy has been applied in the
current work to the preparation of peptide-functionalized NPs with
potential applications in drug delivery. According to the measurements
of particle size and zeta potential, the radiolabeling process did
not result in a statistically significant alteration of the physicochemical
properties of the NPs. Moreover, radiochemical stability studies showed
no detachment of the radioactivity from NPs even at 12 h after preparation.
The radiolabeled NPs enabled the in vivo quantification of the biodistribution
data in rats using a combination of imaging techniques, namely, PET
and computerized tomography (CT). Low accumulation of the nanoparticles
in the liver and their elimination mainly via urine was found. The
different biodistribution pattern obtained for the “free”
radiolabeled polymer suggests chemical and radiochemical integrity
of the NPs under investigation. The strategy reported here may be
applied to any polymeric NPs containing polymers bearing a nucleophile,
and hence our novel strategy may find application for the in vivo
and noninvasive investigation of a wide range of NPs