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Identifier

000419722

Title

Design of functionalized surfaces for acoustic studies of biomolecules

Alternative Title

Σχεδιασμός λειτουργικών επιφανειών για ακουστικές μελέτες ακινητοποιημένων βιομορίων

Author

Παπαγαβριήλ, Φωτεινή Α.

Thesis advisor

Γκιζελή, Ηλέκτρα

Abstract

Acoustic biosensors are analytical devices that use ultrasound waves to extract information about a molecule of interest. More specically, Quartz Crystal Microbalance with Dissipation monitoring (QCM-D) has been used to follow interactions between attached molecules and solid surfaces. Thus QCM-D has been able to probe viscoelastic properties of films formed by biomolecules at the interface between solid surfaces and liquid. In order to monitor these reactions the surface chemistry must be carefully designed. For the quantitative and qualitative interpretation of QCM-D data, we used a discretemolecule binding theory combined with designed surfaces to follow molecular hydrodynamic properties of molecules. The model suggests that the acoustic ratio ΔD/Δf is related to the intrinsic viscosity [η], a measure of the hydrodynamic properties of bound biomolecules. Two different surfaces were used in order to immobilize (a) DNA molecules of various lengths and (b) C terminal constructs of a coiled-coil protein involved in endosomal trafficking. In both cases, Supported Lipid Bilayers (SLB) were first formed, following the binding of discrete molecules that maintain their native structure. For the immobilization of DNA molecules we used the biotin-streptavidin interaction that has been widely exploited for nucleic acid detection using QCM-D monitoring. In previous work biotinylated DNA molecules were immobilized at surfaces covered with neutravidin. In this report we try to elucidate the "linker effect" to evaluate the effect of different linking strategies between the sensor surface and DNA molecules. For this reason we tested the biotin-streptavidin system on Supported Lipid Bilayers (SLBs). The results suggest that the "linker" between sensor surface and target DNA, affects significantly the acoustic measurements. For the specific immobilization of Early endosomal antigen 1 (EEA1) constructs, SLBs containing Phosphatidylinositol 3-phosphate (PI3P) lipids were prepared. In order to apply the discrete molecule approach we used different protein concentration on those surfaces. This particular SLB lipid composition allowed the stable immobilization of protein constructs and preliminary acoustic measurements were evaluated.

Language

English

Subject

Acoustic biosensors

Biosensors

Capturing dna

EEA1

Ακουστικοί βιοαισθητήρες

Βιοαισθητήρες

Δεοξυριβονουκλεικό οξύ

Issue date

2018-11-23