Dokument: Static and dynamic properties of bio-mimetic systems
| Titel: | Static and dynamic properties of bio-mimetic systems | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=42967 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20170726-133058-8 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Dr. De Sio, Silvia [Autor] | |||||||
| Dateien: |
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| Beitragende: | PD Dr. Lang, Peter R [Gutachter] Prof. Dr. Dhont, Jan [Gutachter] | |||||||
| Stichwörter: | statics, dynamics, bio-mimetic | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 530 Physik | |||||||
| Beschreibung: | Summary
Micrometric colloidal spheres coated with SgsE-EGFP have been studied via TIRM to investigate the stabilization of the pair-wise interactions due to forces, known as hydration, arising in protein systems when the components are found extremely close to each other and at very high salt concentrations (in some studies of about 1M). We wanted to test if such stabilization process would be a general property of protein systems, thus emerging also in the specific one we chose for our investigations. This seemed indeed to be the case, even though just a qualitative examination of the measured interaction potentials was possible. Further on, binary mixtures of micrometric colloidal spheres and wild type fd-virus have been studied via TIRM for the investigation of pair-wise depletion interactions beyond the limits of low density and Derjaguin’s approximation. In literature numerical evaluations show that: the violation of Derjaguin’s approximation, tus at ratios of rod-length over sphere radius 𝐿/𝑅=2, brings to a contact potential value three times smaller than predicted one, while the violation of the low density approximation brings to a reduction of the interaction strength of about 6% the value, at rods concentrations as high as 10 times the overlap. So, to investigate the consequences of the violation of Derjaguin’s approximation, we used micrometric spheres of four different sizes, 1-2-3-4 μm in diameter, to span a range of length over sphere radius of 0.44<𝐿/𝑅<1.76 (being the length of fd-viruses L=880 nm); while low density approximation has been probed changing the rods concentrations in the range 0.85c^*≤c≤14c^* (being 𝑐∗=0.07 mg/mL the overlap concentration of the system fd). A detachment from the model predictions is shown by the largest probes used and just above 10×c^*, whereas the smaller probes fall perfectly within the model. We could thus conclude that is the violation of the low density approximation causing the break-down respect to the model and not the high 𝐿/𝑅 ratios. The same data were also investigated in terms of TIRM dynamics: at first, via the calculation of intensity over time auto-correlation functions (ITACF) and consequent evaluation of averaged normal diffusion coefficients, 〈D_n^TIRM 〉; then calculating MDs and MSDs height by height to extract respectively drift velocities, v(h), and normal diffusion coefficients, D_n (h), in function of the heights. In the latter evaluations normal diffusion coefficients show a detachment from the theoretical predictions and always in the case of the largest probe spheres used, possibly being the footprints of the break down observed in the static treatment. This misalignment respect to the theory though is not verified by the drift velocities which perfectly follow the theoretical predictions for all the probes and all fd-concentrations. With further analysis we could conclude that indeed the putative decrease/increase in viscosity pictured by the averaged normal diffusion coefficients and by the normal diffusion coefficients height by height was just an artifact due to the improper neglecting of the external force field acting on a particle in the close vicinity of a wall. | |||||||
| Lizenz: |  Urheberrechtsschutz | |||||||
| Fachbereich / Einrichtung: | Mathematisch- Naturwissenschaftliche Fakultät » WE Physik | |||||||
| Dokument erstellt am: | 26.07.2017 | |||||||
| Dateien geändert am: | 26.07.2017 | |||||||
| Promotionsantrag am: | 30.06.2016 | |||||||
| Datum der Promotion: | 25.07.2017 |
