7 research outputs found
Size Dependence of Steric Shielding and Multivalency Effects for Globular Binding Inhibitors
Competitive binding inhibitors based on multivalent nanoparticles have shown
great potential for preventing virus infections. However, general design
principles of highly efficient inhibitors are lacking as the quantitative
impact of factors such as virus concentration, inhibitor size, steric
shielding, or multivalency effects in the inhibition process is not known.
Based on two complementary experimental inhibition assays we determined size-
dependent steric shielding and multivalency effects. This allowed us to adapt
the Cheng–Prusoff equation for its application to multivalent systems. Our
results show that the particle and volume normalized IC50 value of an
inhibitor at very low virus concentration predominantly depends on its
multivalent association constant, which itself exponentially increases with
the inhibitor/virus contact area and ligand density. Compared to multivalency
effects, the contribution of steric shielding to the IC50 values is only
minor, and its impact is only noticeable if the multivalent dissociation
constant is far below the virus concentration, which means if all inhibitors
are bound to the virus. The dependence of the predominant effect, either
steric shielding or multivalency, on the virus concentration has significant
implications on the in vitro testing of competitive binding inhibitors and
determines optimal inhibitor diameters for the efficient inhibition of
viruses
Multivalenz-assoziierte Eigenschaften von polysulfatierten Nanomaterialien in biomedizinischen Anwendungen
1\. Introduction 1.1 Multivalency and binding inhibition 1.1.1 Definition and
quantification of multivalency 1.1.2 Multivalency in competitive binding
inhibition 1.2 Polysulfates and their biological interactions 1.2.1 Anti-
inflammatory properties of polysulfates 1.2.3 Polyanions and their application
as viral entry inhibitors 1.3 Inorganic nanomaterials for biomedical
applications 1.3.1 Stability of colloidal dispersions – The DLVO theory 1.3.2
Biocompatibility of colloids 1.3.3 Synthesis of inorganic nanoparticles 1.3.4
Stabilizing ligands and functionalization of inorganic nanoparticles 1.3.5
Material-derived properties and applications of inorganic nanomaterials 1.3.6
Dimension-derived properties and applications of inorganic nanomaterials 2\.
Motivation and Objective 3\. Publications and Manuscripts 3.1
Polyglycerolsulfate functionalized gold nanorods as optoacoustic signal
nanoamplifiers for in vivo bioimaging of rheumatoid arthritis 3.2 Virus
inhibition induced by polyvalent nanoparticles of different sizes 3.3 Size
Dependence of Steric Shielding and Multivalency Effects for Globular Binding
Inhibitors 4\. Summary and Conclusion 5\. Outlook 6\. Abstract and
Kurzzusammenfassung 6.1 Abstract 6.2 Kurzzusammenfassung 7\. ReferencesWithin the scope of this thesis, gold nanomaterials of different sizes and
shapes were synthesized and functionalized with polyglycerolsulfates. Their
targeting properties for inflammatory diseases as well as their application as
virus entry inhibitors were evaluated, with special focus on the multivalent
enhancement of their binding affinity to biological surfaces. The first part
of my thesis was concerned with the synthesis and evaluation of
polyglycerolsulfate functionalized gold nanorods (AuNR-dPGS) as contrast agent
for the imaging of rheumatoid arthritis via multispectral optoacoustic
tomography (MSOT). A novel procedure for the anionic functionalization of gold
nanorods was established by a thermally induced ligand exchange of
PEG1000-thiol with thioctic acid-dPGS 10 kDa. As a result, the prepared
nanorods were significantly less cytotoxic than other polyanionic nanorods in
the literature. The active targeting properties of AuNR-dPGS for inflammatory
diseases could be affirmed in vitro and in vivo, which successfully showed
that the large contact area of colloids with the biological surface results in
strong binding affinities. The second part of my thesis was focused on a
detailed investigation on the mechanism of globular binding inhibition and the
possible application of polysulfated gold nanoparticles (AuNP-PGS) as viral
entry inhibitors. The investigations on the size dependent inhibition of
vesicular stomatitis virus (VSV) with AuNP-PGS indicated that the inhibition
potential of globular inhibtors is strongly size dependent and that the
infection inhibition is based on the inhibition of the virus’ binding to the
cells. The follow-up study elucidated the mechanism of competitive binding
inhibition in detail. The effect of steric shielding and the multivalent
enhancement of binding affinities due to larger contacts areas of inhibitors
and binders on the competitive binding inhibition could be quantitatively
described theoretical models. It is now possible to predict the optimal
inhibitor sizes for mass efficient virus inhibition and rationally design
competitive binding inhibitors.In der vorliegenden Arbeit wurden Goldkolloide unterschiedlicher Form und
Größe synthetisiert und mit Polyglycerinsulfaten beschichtet. Der mögliche
Einsatz der Nanomaterialien zur gezielten Diagnostik von
Entzündungskrankheiten sowie als Virusinhibitoren wurden untersucht, wobei ein
besonderes Augenmerk auf die Untersuchung der Multivalenz bedingten
Verstärkung der Bindungsaffinitäten gelegt wurde. Der erste Teil meiner Arbeit
beschäftigte sich mit der Synthese und Evaluation von Polyglycerinsulfat-
funktionalisierten Goldnanostäbchen (AuNR-dPGS) als Kontrastmittel für die
Abbildung von rheumatoider Arthritis mittels multispektraler optoakustischer
Tomographie (MSOT). Auf Basis einer thermisch-induzierten
Ligandenaustauschreaktion von PEG1000-Thiol mit Thioctsäure-dPGS 10 kDa wurde
eine neuartige Methode zur anionischen Beschichtung von Goldnanostäbchen
eingeführt, welche die Zytotoxizität der Stäbchen im Vergleich zu anderen
Methoden in der Literatur signifikant verringerte. Die aktive Zielführung von
AuNR-dPGS zu Entzündungskrankheiten konnte in in vitro sowie in vivo
Experimenten bestätigt werden, wodurch erfolgreich gezeigte wurde, dass die
großen Kontaktfläche von Kolloiden mit biologischen Oberflächen die
Bindungsaffinitäten stark verstärken. Der zweite Teil meiner Arbeit war auf
die mechanistische Aufklärung der kompetitiven Bindungsinhibition durch
globuläre Inhibitoren und der möglichen Anwendung von polysulfatierten
Goldnanopartikeln (AuNP-PGS) für die Inhibition von Virus-Zell Bindungen
fokussiert. Die Untersuchungen zur größenabhängige Inhibition des Vesicular
Stomatitis Virus (VSV) mittels AuNP-dPGS haben gezeigt, dass das
Inhibitionspotential von globulären Inhibitoren stark größenabhängig ist und
dass die Inhibition der Infektion hauptsächlich auf der Inhibition der Virus-
Zell Bindung beruht. In dem darauffolgendem Projekt wurde der Mechanismus der
kompetitiven Bindungsinhibition aufgeklärt. Die Auswirkungen der sterischen
Abschirmung von Viren durch Inhibitoren sowie von Multivalenzeffekten auf die
Bindungsinhibition konnten quantifiziert und mit theoretischen Modellen
aufgeklärt werden. Optimale Durchmesser von globulären Inhibitoren können nun
vorhergesagt werden, womit die Möglichkeit zur rationellen Entwicklung von
Virusinhibitoren gegeben ist