4 research outputs found
Nonuniform Growth of Composite Layer-by-Layer Assembled Coatings via Three-Dimensional Expansion of Hydrophobic Magnetite Nanoparticles
Nanocomposite coatings are promising
for a range of practical applications,
and layer-by-layer assembly (LbL) is a versatile tool for nanocomposite
formation. However, conventional LbL is a quite laborious procedure
taking a lot of time to reach a sufficient thickness of the coatings
required for practical applications. Herein, we proposed a novel variant
of the LbL approach based on the deposition of hydrophilic polyelectrolyte
molecules from a polar solvent and hydrophobic magnetite nanoparticles
(NPs) from a nonpolar dispersion medium with an intermediate washing
in the same polar solvent. The composite multilayers formed in this
way exhibit exponential growth of the thickness and mass. On the basis
of quartz crystal microbalance (QCM), Fourier transform infrared spectroscopy
(FTIR), scanning electron microscopy (SEM), atomic force microscopy
(AFM), and surface profile measurements, we propose a model describing
the driving force of multilayer formation and the factors leading
to nonlinear growth of their mass and thickness. The results allow
one to expand the understanding of the mechanism of the LbL assembly
in order to form multifunctional nanocomposites in a more efficient
way
Effect of Surface Functionalization of Metal Wire on Electrophysical Properties of Inductive Elements
The development of the microelectronics industry requires
a new
element basis with reduced size and increased functionality. The most
important components in modern microelectronic integrated circuits
are passive elements. One of the key challenges in order to improve
the functionality of integrated circuits is to increase the quality
of passive elements composing them. In this paper we suggest a novel
approach to increase the quality factor Q of inductors by the surface
modification and functionalization of the metal components. Ultrasound
induced surface modification of metal wires led to the formation of
a porous surface structure, which further can be functionalized with
magnetite nanoparticles using layer-by-layer assembly technique. The
surface modification and deposition of magnetite nanoparticles was
investigated with SEM, XRD, and contact angle measurements. Additionally,
inductance and resistance measurements, as the main parameters determining
the Q-factor of inductors, were carried out. Samples with high number
of magnetic nanoparticle–polyelectrolyte bilayers demonstrate
a significant increase in inductance and a slight decrease in resistance
in comparison to uncoated ones. The combination of these factors led
to enhancement the Q-factor of the investigated inductive elements
New Surface-Enhanced Raman Scattering Platforms: Composite Calcium Carbonate Microspheres Coated with Astralen and Silver Nanoparticles
Surface-enhanced
Raman scattering (SERS) microspectroscopy is a
very promising label-free, noncontact, and nondestructive method for
real-time monitoring of extracellular matrix (ECM) development and
cell integration in scaffolds for tissue engineering. Here, we prepare
a new type of micrometer-sized SERS substrate, core–shell microparticles
composed of solid carbonate core coated with silver nanoparticles
and polyhedral multishell fullerene-like structure, astralen. Astralen
has been assembled with polyallylamine hydrochloride (PAH) by the
layer-by-layer manner followed by Ag nanoparticle formation by means
of a silver mirror reaction, giving the final structure of composite
particles CaCO<sub>3</sub>(PAH/astralen)<sub><i>x</i></sub>/Ag, where <i>x</i> = 1–3. The components of the
microparticle carry multiple functionalities: (i) an easy identification
by Raman imaging (photostable astralen) and (ii) SERS due to a rough
surface of Ag nanoparticles. A combination of Ag and astralen nanoparticles
provides an enhancement of astralen Raman signal by more than 1 order
of magnitude. Raman signals of commonly used scaffold components such
as polylactide and polyvinyl alcohol as well as ECM component (hyaluronic
acid) are significantly enhanced. Thus, we demonstrate that new mechanically
robust and easily detectable (by astralen signal or optically) core–shell
microspheres based on biocompatible CaCO<sub>3</sub> can be used as
SERS platform. Particle design opens many future perspectives for
fabrication of SERS platforms with multiple functions for biomedical
applications, for example, for theranostic
Multilayer Capsules of Bovine Serum Albumin and Tannic Acid for Controlled Release by Enzymatic Degradation
With
the purpose to replace expensive and significantly cytotoxic positively
charged polypeptides in biodegradable capsules formed via Layer-by-Layer
(LbL) assembly, multilayers of bovine serum albumin (BSA) and tannic
acid (TA) are obtained and employed for encapsulation and release
of model drugs with different solubility in water: hydrophilic-tetramethylrhodamine-isothiocyanate-labeled
BSA (TRITC-BSA) and hydrophobic 3,4,9,10-tetra-(hectoxy-carbonyl)-perylene
(THCP). Hydrogen bonding is proposed to be predominant within thus
formed BSA/TA films. The TRITC-BSA-loaded capsules comprising 6 bilayers
of the protein and polyphenol are benchmarked against the shells composed
of dextran sulfate (DS) and poly-l-arginine (PARG) on degradability
by two proteolytic enzymes with different cleavage site specificity
(i.e., α-chymotrypsin and trypsin) and toxicity for murine RAW264.7
macrophage cells. Capsules of both types possess low cytotoxicity
taken at concentrations equal or below 50 capsules per cell, and evident
susceptibility to α-chymotrypsin resulted in release of TRITC-BSA.
While the BSA/TA-based capsules clearly display resistance to treatment
with trypsin, the assemblies of DS/PARG extensively degrade. Successful
encapsulation of THCP in the TRITC-BSA/TA/BSA multilayer is confirmed,
and the release of the model drug is observed in response to treatment
with α-chymotrypsin. The thickness, surface morphology, and
enzyme-catalyzed degradation process of the BSA/TA-based films are
investigated on a planar multilayer comprising 40 bilayers of the
protein and polyphenol deposited on a silicon wafer. The developed
BSA/TA-based capsules with a protease-specific degradation mechanism
are proposed to find applications in personal care, pharmacology,
and the development of drug delivery systems including those intravenous
injectable and having site-specific release capability