## Dr. - Ing. Ekaterina Gongadze

**Member of the Research Training Group, 1.10.2008 - 31.09.2011**

**PhD Defence 20.09.2012, Magna Cum Laude**

**Dr. Ekaterina Gongadze**

**University** of Rostock**Faculty** of Computer Science and Electrical Engineering**Institute** of General Electrical Engineering

**Phone**: +49-381-498-70 79**Fax**: +49-381-498-118 70 81**www**: www.iae.uni-rostock.de**Email**: ekaterina.gongadze(at)uni-rostock.de

### Topic

Influence of the Surface Structure of a Biomaterial on the Field Distribution in the Neighbouring Biosystem.

### Description

In summary, the objective of this research is to develop electric double layer (EDL) models intended to be reasonably complete with respect not only to the main properties of the system but also to some of its specifications. Consequentially, the long term aim of the project is to improve the biocompatibility and endurance of a hip endoprosthesis.

### Approach

In essence, this project progresses in the following three stages:

- Study of the so-called classical models of EDL theory by distinguishing their advantages and drawbacks.
- Further improvement of the Poisson-Boltzmann theory by taking into account the spatial variation of the relative permittivity.
- Application of the developed models to a structured implant in order to shed light on the difference between convex and flat parts, which could explain why an osteoblast would prefer to adhere exactly at sharp convex edges.

### Results

So far the following results have been achieved:

- Study of the so-called classical models of EDL theory by distinguishing their advantages and drawbacks.
- Further improvement of the Poisson-Boltzmann theory by creation of a Generalized Stern model (GSM), which phenomenologically would take into account the spatial variation of the relative permittivity.
- A sophistication of the above mentioned model by the use of statistical thermodynamics to define a Langevin Poisson-Boltzmann model (LPBM) for point-like ions. Here, the spatial variation of the relative permittivity is the result of the theory developed and has an exponential distribution dependent on the local electric field strength.
- The advancement of the LPBM was continued by taking into account the excluded volume effect (Langevin-Bikerman model (LBM)). The distribution of ions and water dipoles and the spatial variation of the relative permittivity are the result of the variational procedure of the free energy of the system in a self-consistent way.
- Application of the GSM to a structured implant in order to shed light on the difference between convex and flat parts, which could explain why an osteoblast would prefer to adhere exactly at sharp convex edges.
- Validation of the results by comparing the capacitance of the EDL obtained analytically, numerically and experimentally.

### Publications

**Books:**

E. Gongadze, K. Bohinc, U. van Rienen, Veronika Kralj- Iglič, A. Iglič. Spatial variation of permittivity near a charged membrane in contact with electrolyte solution, Advances in Planar Lipid Bilayers and Liposomes (APLBL), Vol.11, Elsevier 2010, Amsterdam

E. Gongadze, Š. Perutková, K. Bohinc, U. van Rienen, Veronika Kralj- Iglič, A. Iglič, D. Kabaso. Electromechanical basis for the interaction between osteoblasts and negatively charged titanium surface, Advances in Planar Lipid Bilayers and Liposomes (APLBL), Vol.13, Elsevier 2011, Amsterdam

**Journals:**

GONGADZE, E., VAN RIENEN, U., KRALJ-IGLIČ, V. and IGLIČ, A., 2014. Spatial variation of permittivity of an electrolyte solution in contact with a charged metal surface: a mini review, Computer Methods in Biomechanics and Biomedical Engineering, 17 (3), pp. 296-296. DOI: 10.1080/10255842.2012.678684 (ein Corrigendum)

GONGADZE, E., VAN RIENEN, U., KRALJ-IGLIČ, V. and IGLIČ, A., 2013. Spatial variation of permittivity of an electrolyte solution in contact with a charged metal surface: a mini review. Computer Methods in Biomechanics and Biomedical Engineering, 16 (5), pp. 463-480. DOI: 10.1080/10255842.2011.624769.

GONGADZE, E., KRALJ-IGLIČ, V., VAN RIENEN, U. and IGLIČ, A., 2011. Derivation of Langevin Poisson-Boltzmann equation for point-like ions using functional density theory. Elektrotehniski Vestnik/Electrotechnical Review, 78 (1), pp. 1-4.

GONGADZE, E., VAN RIENEN, U., KRALJ-IGLIČ, V. and IGLIČ, A., 2011. Langevin Poisson-Boltzmann equation: point-like ions and water dipoles near a charged membrane surface. General Physiology and Biophysics, 30 (2), pp.130-137. DOI: 10.4149/gpb_2011_02_130.

GONGADZE, E., KABASO, D., BAUER, S., SLIVNIK, T., SCHMUKI, P., VAN RIENEN, U. and IGLIČ, A., 2011. Adhesion of osteoblasts to a nanorough implant titanium surface. International Journal of Nanomedicine, 6, pp. 1801–1816. DOI:10.2147/IJN.S21755.

GONGADZE, E., VAN RIENEN, U. and IGLIČ, A., 2011. Generalized Stern models of the electric double layer considering the spatial variation of permittivity and finite size of ions in saturation regime, Cellular and Molecular Biology Letters, pp. 576-594. DOI: 10.2478/s11658-011-0024-x.

KABASO, D., GONGADZE, E., ELTER, P., VAN RIENEN, U., GIMSA, J., KRALJ-IGLIČ, V. and IGLIČ, A., 2011. Attachment of rod-like (BAR) proteins and membrane shape. Mini-Reviews in Medicinal Chemistry, 11 (4), pp. 272-282.

KABASO, D., GONGADZE, E., PERUTKOVÀ, Š., MATSCHEGEWSKI, C., KRALJ-IGLIČ, V., BECK U., VAN RIENEN, U. and IGLIČ, A., 2011. Mechanics and electrostatics of the interactions between osteoblasts and titanium surface. Computer Methods in Biomechanics and Biomedical Engineering, 14 (5), pp. 469-482.

KABASO, D., GONGADZE, E., JORGAČEVSKI, J., VAN RIENEN, U., ZOREC, R. and IGLIČ, A., 2011. Exploring the binding dynamics of BAR proteins. Cellular and Molecular Biology Letters, 16, pp. 398-411. DOI: 10.2478/s11658-011-0013-0.

BOHINC, K., GONGADZE, E., KRALJ-IGLIČ, V., VAN RIENEN, U. and IGLIČ, A., 2010. Metal surface in contact with electrolyte solution - Influence of spatial variation of dielectric constant. Elektrotehniski Vestnik/Electrotechnical Review, 77 (2-3), pp. 121-130.

IGLIČ, A., GONGADZE, E. and BOHINC, K., 2010. Excluded volume effect and orientational ordering near charged surface in solution of ions and Langevin dipoles. Bioelectrochemistry, 79 (2), pp. 223-227.

**Conferences:**

GONGADZE, E., PERUTKOVA, Š., VAN RIENEN, U. and IGLIČ, A., 2011. Mechanics and electrostatics of the interactions between osteoblasts and nanostructured surface of titanium implants, Advances in biomechanics and mechanobiological modelling, University of Oxford, England, 21st April 2011.

GONGADZE, E., VAN RIENEN, U. and IGLIČ, A., 2011. An electric double layer model with a space dependent permittivity near a charged titanium implant surface, 21st International Symposium on Bioelectrochemistry and Bioenergetics, Cracow, Poland, pp. 320.

IGLIČ, A., GONGADZE, E., KABASO, D., PERUTKOVA, Š., KRALJ-IGLIČ, V., IGLIČ, A. and VAN RIENEN, U., 2011. Electrostatics and mechanics of the interactions between osteoblasts and a surface of titanium implants, 21st International Symposium on Bioelectrochemistry and Bioenergetics, Cracow, Poland, pp. 297.

IGLIČ, A., GONGADZE, E., KABASO, D., PERUTKOVA, Š., VAN RIENEN, U. and KRALJ-IGLIČ, V., 2011. Mechanics and electrostatics of the interactions between cells and surface of titanium implants, 18th Meeting European Association of Red Cell Research (EARCR), Wroclaw-Piechowice, Poland, pp. 25.

GONGADZE, E., IGLIČ, A., PETERSEN, S. and VAN RIENEN, U., 2010. An Electrical Double Layer Model with Spatial Variation of the Permittivity. International Symposium on Electromagnetic Theory (EMTS 2010), pp. 540-543.

GONGADZE, E., IGLIČ, A. and VAN RIENEN, U., 2010. Electric double layer on geometrically structured implants. Conf. IEEE - ERK'2010 Portoroz, Slovenian section IEEE, B, pp. 339-342.

GONGADZE, E., PETERSEN, S., IGLIČ, A.and VAN RIENEN, U., 2010. Elektrische Doppelschicht und Strukturierte Titan Implantate (Electrical Double Layer and Structured Titanium Implants). Biomedizinische Technik/Biomedical Engineering, 55 (1), pp.171-174. DOI:10.1515/BMT.2010.712.

IGLIČ, A., GONGADZE, E., PERUTKOVÀ, Š., BOHINC, K., BOBOJEVIC G., VAN RIENEN, U. and KRALJ-IGLIČ, V., 2010. Interactions between titanium surface and osteoblasts mediated by positively charged. Proceeding of Computer Methods in Biomechanics and Biomedical Engineering Valencia, Spain, pp. 92-97.

### Supervisors

In addition to the entire graduate school, my supervisors are:

- Prof. Dr. Ursula van Rienen
- PD Dr. Ulrich Beck
- Prof. Dr. Jan Gimsa
- Prof. Dr. Ales Iglic