Assoc. Prof. Lachezar Christov

Laboratory of Water soluble polymers, amphiphiles and biopolymers

The characteristic properties of polyzwitterions creating the basis of their unique biocompatibility are their low absorptivity into proteins, the preservation of the cell adhesion and nonbiofouling. An explanation of the nonbiofouling properties of polyzwitterions is proposed. The existence of an osmotic component of the driving force of the antipolyelectrolyte effect and the parameters governing this phenomenon are quantitatively established. The correlation between this effect, which is specific of the polyzwitterions only, and their nonbiofouling properties is grounded.

The formation of macromolecular self-assemblies resulting from a dipole-dipole interaction between the zwitterionic side groups of the polyzwitterionic polymer in its an aqueous, saltless solutions is proved by viscosimetrically and dynamic laser light scattering. The behavior of these self-assemblies in the presence of surfactants is determined by the interrelation of the two types of driving forces for self-association: dipole-dipole and hydrophobic interaction. This interrelation is controlled by the molar ratio of the surfactants and the zwitterionic monomer units, which bear the material causes for these interactions.

The relationship between polyzwitterions antipolyelectrolyte properties and their excellent biocompatibility expressed in terms of the suppression of blood clot and amyloid-fibril formation is discussed. It is used for the explanation of the polyzwitterions applications for production of the high quality cosmetics materials, soft contact lens, biolubricants, coronary vascular prosthesis, catheters, haemodialyses membranes, angiosurgery stents. The effective application of the polyzwitterions as the impressive materials against amyloid-fibril formation at many neurodegenerative diseases is suggested too.


1.Georgiev, G. S., A. A. Tzoneva, S. B. Iliev, I. P. Kamenova, V. T. Georgieva, E. B. Kamenska, A. Bund, Electrostimulated Shift of the Precipitation Temperature of Aqueous Polyzwitterionic Solutions, Macromol. Symp. 210 (2004) 393.

2. Georgiev, G., E. Kamenska, E. Vassileva, I. Kamenova, V. Georgieva, S. Iliev, I. Ivanov, Properties and biomedical application of polyzwitterions, Ann. Univ. Sofia, Chem. 98-99 (2005) 305.

3. Georgiev, G., I. Kamenova, V. Georgieva, E. Kamenska, R. Hempelmann, H. Natter, Poly(dimethylaminoethylmethacryloylpropanesulfonate) suitable polymer additive for pulsed electrodeposition of nanocrystalline nickel, J. Appl. Polym. Sci.  102 (2006) 2967.

4. Kamenska, E., E. Vassileva, I. Kamenova, A. Tzoneva, V. Georgieva, S. Iliev G. Georgiev, A new approach to the description and control of the unique biocompatibility of polyzwitterions, Comptes rendus de L’Academie des Sciences, Chem. 38 (2006) 49.

5. Georgiev, G., E. Kamenska, E. Vassileva, I. Kamenova, V. Georgieva, S. Iliev, I. Ivanov, Self-Assembly, Antipolyelectrolyte Effect and Nonbiofouling Properties of Polyzwitterions, Biomacromolecules 7 (2006) 1329.

6. Ivanov, I., I. Kamenova, V. Georgieva, E. Kamenska, G. Georgiev, Mixed Surfactant- Polyzwitterion Self-Assemblies in Aqueous Solutions, Colloid Surf. A. Physicochem. Eng. Asp. 282-283 (2006) 129.



Novel stable zwitterionic copolymer latex with different compositions has been synthesized by emulsifier-free emulsion copolymerization. These new zwitterionic copolymer latexes have been used for the preparation of the model drug tablets for sustained Metoprolol tartrate and Verapamil hydrochloride release. The swelling kinetics of the zwitterionic copolymer tablets shows relationship between their unusual “overshooting” behavior and the specific self-association of the copolymers. It is established that the variation of the zwitterionic monomer concentration, pH and ionic strength effects on this relationship, on the swelling kinetics, and on the sustained Metoprolol tartrate and Verapamil hydrochloride release from these tablets.


1. Kamenska, E., B. Kostova, I. Ivanov, D. Rachev, G. Georgiev, Emulsifier-free emulsion copolymerization of vinyl acetate and 3-dimethyl(methacryloyloxyethyl) ammonium propane sulfоnate and swelling behavior of their copolymer matrices, Macromol. React. Eng. 1 (5) (2007) 553.

2. Kostova, B., E. Kamenska, I. Ivanov, G. Momekov, D. Rachev, G. Georgiev, Verapamil hydrochloride Release Characteristics from New Co-polymer Zwitterionic Matrix Tablets, Pharm. Devel. Techn. 13 (2008) 311.

3. Smilkov, H., I. Kamenova, E. Kamenska, Ch. Betchev, G. Georgiev, Biocompatible Zwitterionic Copolymer Networks with Controllable Swelling and Mechanical Characteristics of their Hydrogels, J. Mater. Sci.: Mater. Med. 19 (2008) 2389-2395.

4. Kamenska, E., B. Kostova, I. Ivanov, D. Rachev, G. Georgiev, Synthesis and characterization of zwitterionic copolymers as matrices for sustained Metoprolol tartrate delivery, J. Biometer. Sci., Polym. Ed. 20 (2009) 181.

5. Kostova, B., E. Kamenska, N. Dimitrov, D. Rachev, G. Georgiev, Morphology of new zwitterionic copolymer matrices for sustained drug release, Paper contribution for the 11th European Symposium on Controlled Drug Delivery, 7-12 April, Netherlands.