13 research outputs found
A Structural Comparison of Organoterminated Selenide, Diselenide, and Triselenide
<div><p>GRAPHICAL ABSTRACT</p><p></p></div
How Bound and Free Fatty Acids in Cellulose Films Impact Nonspecific Protein Adsorption
The effect of fatty
acids and fatty acid esters to impair nonspecific
protein adsorption on cellulose thin films is investigated. Thin films
are prepared by blending trimethylsilyl cellulose solutions with either
cellulose stearoyl ester or stearic acid at various ratios. After
film formation by spin coating, the trimethylsilyl cellulose fraction
of the films is converted to cellulose by exposure to HCl vapors.
The morphologies and surface roughness of the blends were examined
by atomic force microscopy revealing different feature shapes and
sizes depending on the blend ratios. Nonspecific protein adsorption
at the example of bovine serum albumin toward the blend thin films
was tested by means of surface plasmon resonance spectroscopy in real-time.
Incorporation of stearic acid into the cellulose leads to highly protein
repellent surfaces regardless of the amount added. The stearic acid
acts as a sacrificial compound that builds a complex with bovine serum
albumin thereby inhibiting protein adsorption. For the blends where
stearoyl ester is added to the cellulose films, the cellulose:cellulose
stearoyl ester ratios of 3:1 and 1:1 lead to much lower nonspecific
protein adsorption compared to pure cellulose, whereas for the other
ratios, adsorption increases. Supplementary results were obtained
from atomic force microscopy experiments performed in liquid during
exposure to protein solution and surface free energy determinations
209Bi Quadrupole Relaxation Enhancement in Solids as a Step Towards New Contrast Mechanisms in Magnetic Resonance Imaging
<p>Motivated by the possibility of exploiting species containing high spin quantum number<br>
nuclei (referred to as quadrupole nuclei) as novel contrast agents for Magnetic Resonance<br>
Imaging, based on Quadrupole Relaxation Enhancement (QRE) effects, 1H spin-lattice<br>
relaxation has been investigated for tris(2-methoxyphenyl)bismuthane and tris(2,6-<br>
dimethoxyphenyl)bismuthane in powder. The relaxation experiment has been performed in<br>
the magnetic field range of 0.5 T to 3 T (the upper limit corresponds to the field used in many<br>
medical scanners). A very rich QRE pattern (several frequency specific 1H spin-lattice<br>
relaxation rate maxima) has been observed for both compounds. Complementary Nuclear<br>
Quadrupole Resonance experiments have been performed in order to determine the<br>
quadrupole parameters (quadrupole coupling constant and asymmetry parameters) for 209Bi.<br>
Knowing the parameters, the QRE pattern has been explained on the basis of a quantummechanical<br>
picture of the system including single and double-quantum coherences for the<br>
participating nuclei (1H and 209Bi). In this way the quantum-mechanical origin of the spintransitions leading to the QRE effects has been explained.</p
Adsorption Studies of Organophosphonic Acids on Differently Activated Gold Surfaces
In this study, the formation of self-assembled
monolayers consisting
of three organophosphonic acids (vinyl-, octyl-, and tetradecylphosphonic
acid) from isopropanol solutions onto differently activated gold surfaces
is studied in situ and in real time using multiparameter surface plasmon
resonance (MP-SPR). Data retrieved from MP-SPR measurements revealed
similar adsorption kinetics for all investigated organophosphonic
acids (PA). The layer thickness of the immobilized PA is in the range
of 0.6–1.8 nm corresponding to monolayer-like coverage and
correlates with the length of the hydrocarbon chain of the PA molecules.
After sintering the surfaces, the PA are irreversibly attached onto
the surfaces as proven by X-ray photoelectron spectroscopy and attenuated
total reflection infrared and grazing incidence infrared spectroscopy.
Potential adsorption modes and interaction mechanisms are proposed
Additional file 1 of Engineering Saccharomyces cerevisiae for targeted hydrolysis and fermentation of glucuronoxylan through CRISPR/Cas9 genome editing
Supplementary Material 1: MOCLO cloning strateg
Interaction of Tissue Engineering Substrates with Serum Proteins and Its Influence on Human Primary Endothelial Cells
Polymer-based biomaterials
particularly polycaprolactone (PCL)
are one of the most promising substrates for tissue engineering. The
surface chemistry of these materials plays a major role since it governs
protein adsorption, cell adhesion, viability, degradation, and biocompatibility
in the first place. This study correlates the interaction of the most
abundant serum proteins (albumin, immunoglobulins, fibrinogen) with
the surface properties of PCL and its influence on the morphology
and metabolic activity of primary human arterial endothelial cells
that are seeded on the materials. Prior to that, thin films of PCL
are manufactured by spin-coating and characterized in detail. A quartz
crystal microbalance with dissipation (QCM-D), a multiparameter surface
plasmon resonance spectroscopy instrument (MP-SPR), wettability data,
and atomic force microscopy are combined to elucidate the pH-dependent
protein adsorption on the PCL substrates. Primary endothelial cells
are cultured on the protein modified polymer, and conclusions are
drawn on the significant impact of type and form of proteins coatings
on cell morphology and metabolic activity
Enzymes as Biodevelopers for Nano- And Micropatterned Bicomponent Biopolymer Thin Films
The creation of nano- and micropatterned
polymer films is a crucial
step for innumerous applications in science and technology. However,
there are several problems associated with environmental aspects concerning
the polymer synthesis itself, cross-linkers to induce the patterns
as well as toxic solvents used for the preparation and even more important
development of the films (e.g., chlorobenzene). In this paper, we
present a facile method to produce micro- and nanopatterned biopolymer
thin films using enzymes as so-called biodevelopers. Instead of synthetic
polymers, naturally derived ones are employed, namely, poly-3-hydroxybutyrate
and a cellulose derivative, which are dissolved in a common solvent
in different ratios and subjected to spin coating. Consequently, the
two biopolymers undergo microphase separation and different domain
sizes are formed depending on the ratio of the biopolymers. The development
step proceeds via addition of the appropriate enzyme (either PHB-depolymerase
or cellulase), whereas one of the two biopolymers is selectively degraded,
while the other one remains on the surface. In order to highlight
the enzymatic development of the films, video AFM studies have been
performed in real time to image the development process in situ as
well as surface plasmon resonance spectroscopy to determine the kinetics.
These studies may pave the way for the use of enzymes in patterning
processes, particularly for materials intended to be used in a physiological
environment
Enzymes as Biodevelopers for Nano- And Micropatterned Bicomponent Biopolymer Thin Films
The creation of nano- and micropatterned
polymer films is a crucial
step for innumerous applications in science and technology. However,
there are several problems associated with environmental aspects concerning
the polymer synthesis itself, cross-linkers to induce the patterns
as well as toxic solvents used for the preparation and even more important
development of the films (e.g., chlorobenzene). In this paper, we
present a facile method to produce micro- and nanopatterned biopolymer
thin films using enzymes as so-called biodevelopers. Instead of synthetic
polymers, naturally derived ones are employed, namely, poly-3-hydroxybutyrate
and a cellulose derivative, which are dissolved in a common solvent
in different ratios and subjected to spin coating. Consequently, the
two biopolymers undergo microphase separation and different domain
sizes are formed depending on the ratio of the biopolymers. The development
step proceeds via addition of the appropriate enzyme (either PHB-depolymerase
or cellulase), whereas one of the two biopolymers is selectively degraded,
while the other one remains on the surface. In order to highlight
the enzymatic development of the films, video AFM studies have been
performed in real time to image the development process in situ as
well as surface plasmon resonance spectroscopy to determine the kinetics.
These studies may pave the way for the use of enzymes in patterning
processes, particularly for materials intended to be used in a physiological
environment
Enzymes as Biodevelopers for Nano- And Micropatterned Bicomponent Biopolymer Thin Films
The creation of nano- and micropatterned
polymer films is a crucial
step for innumerous applications in science and technology. However,
there are several problems associated with environmental aspects concerning
the polymer synthesis itself, cross-linkers to induce the patterns
as well as toxic solvents used for the preparation and even more important
development of the films (e.g., chlorobenzene). In this paper, we
present a facile method to produce micro- and nanopatterned biopolymer
thin films using enzymes as so-called biodevelopers. Instead of synthetic
polymers, naturally derived ones are employed, namely, poly-3-hydroxybutyrate
and a cellulose derivative, which are dissolved in a common solvent
in different ratios and subjected to spin coating. Consequently, the
two biopolymers undergo microphase separation and different domain
sizes are formed depending on the ratio of the biopolymers. The development
step proceeds via addition of the appropriate enzyme (either PHB-depolymerase
or cellulase), whereas one of the two biopolymers is selectively degraded,
while the other one remains on the surface. In order to highlight
the enzymatic development of the films, video AFM studies have been
performed in real time to image the development process in situ as
well as surface plasmon resonance spectroscopy to determine the kinetics.
These studies may pave the way for the use of enzymes in patterning
processes, particularly for materials intended to be used in a physiological
environment
Exploring Nonspecific Protein Adsorption on Lignocellulosic Amphiphilic Bicomponent Films
In this contribution, we explore
the interaction of lignocellulosics
and proteins aiming at a better understanding of their synergistic
role in natural systems. In particular, the manufacturing and characterization
of amphiphilic bicomponent thin films composed of hydrophilic cellulose
and a hydrophobic lignin ester in different ratios is presented which
may act as a very simplified model for real systems. Besides detailed
characterizations of the films and mechanisms to explain their formation,
nonspecific protein adsorption using bovine serum albumin (BSA) onto
the films was studied using a quartz crystal microbalance with dissipation
(QCM-D). As it turns out, the rather low nonspecific protein adsorption
of BSA on cellulose is further reduced when these hydrophobic lignins
are incorporated into the films. The lignin ester acts in these blend
films as sacrificial component, probably via an emulsification mechanism.
Additionally, the amphiphilicity of the films may prevent the adsorption
of BSA as well. Although there are some indications, it remains unclear
whether any kind of protein interactions in such systems are of specific
nature