Anton L. Zernov

Cell attachment on poly(3-hydroxybutyrate)-poly (ethylene glycol) copolymer produced by Azotobacter chroococcum 7B

BackgroundThe improvement of biomedical properties, e.g. biocompatibility, of poly(3-hydroxyalkanoates) (PHAs) by copolymerization is a promising trend in bioengineering. We used strain Azotobacter chroococcum 7B, an effective producer of PHAs, for biosynthesis of not only poly(3-hydroxybutyrate) (PHB) and its main copolymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-HV), but also alternative copolymer, poly(3-hydroxybutyrate)-poly(ethylene glycol) (PHB-PEG).ResultsIn biosynthesis we used sucrose as the primary carbon source and valeric acid or poly(ethylene glycol) 300 (PEG 300) as additional carbon sources. The chemical structure of PHB-PEG and PHB-HV was confirmed by 1H nuclear-magnetic resonance (1H NMR) analysis. The physico-chemical properties (molecular weight, crystallinity, hydrophilicity, surface energy) and surface morphology of films from PHB copolymers were studied. To study copolymers biocompatibility in vitro the protein adsorption and COS-1 fibroblasts growth on biopolymer films by XTT assay were analyzed. Both copolymers had changed physico-chemical properties compared to PHB homopolymer: PHB-HV and PHB-PEG had less crystallinity than PHB; PHB-HV was more hydrophobic than PHB in contrast to PHB-PEG appeared to have greater hydrophilicity than PHB; whereas the morphology of polymer films did not differ significantly. The protein adsorption to PHB-PEG was greater and more uniform than to PHB and PHB-PEG copolymer promoted better growth of COS-1 fibroblasts compared with PHB homopolymer.ConclusionsThus, despite low EG-monomers content in bacterial origin PHB-PEG copolymer, this polymer demonstrated significant improvement in biocompatibility in contrast to PHB and PHB-HV copolymers, which may be coupled with increased protein adsorption and hydrophilicity of PEG-containing copolymer.

The Terpolymer Produced by Azotobacter Chroococcum 7B: Effect of Surface Properties on Cell Attachment

The copolymerization of poly(3-hydroxybutyrate) (PHB) is a promising trend in bioengineering to improve biomedical properties, e.g. biocompatibility, of this biodegradable polymer. We used strain Azotobacter chroococcum 7B, an effective producer of PHB, for biosynthesis of not only homopolymer and its main copolymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-HV), but also novel terpolymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate)-poly(ethylene glycol) (PHB-HV-PEG), using sucrose as the primary carbon source and valeric acid and poly(ethylene glycol) 300 (PEG 300) as additional carbon sources. The chemical structure of PHB-HV-PEG was confirmed by 1H nuclear-magnetic resonance analysis. The physico-chemical properties (molecular weight, crystallinity, hydrophilicity, surface energy) of produced biopolymer, the protein adsorption to the terpolymer, and cell growth on biopolymer films were studied. Despite of low EG-monomers content in bacterial-origin PHB-HV-PEG polymer, the terpolymer demonstrated significant improvement in biocompatibility in vitro in contrast to PHB and PHB-HV polymers, which may be coupled with increased protein adsorption, hydrophilicity and surface roughness of PEG-containing copolymer.

Preclinical Toxicity Evaluation of Paclitaxel Biopolymer Formulation

BACKGROUND Poly(hydroxyalkanoates) (PHA) have recently attracted increasing attention due to their biodegradability and high biocompatibility, which makes them suitable for the development of new prolong drug formulations. OBJECTIVE A preclinical toxicology study of paclitaxel biopolymer formulation (PBF) (paclitaxel-loaded poly(3- hydroxybutyrate) (PHB) microparticles) was done in order to assess its safety and to forecast side and toxic effects in a clinical study on patients. METHOD PHB microparticles loaded with antitumor cytostatic drug PTX were obtained by spray-drying method using Nano Spray Dryer B-90. The comprehensive study of cytotoxicity (on bone marrow stem cells), acute and chronic toxicity, allergenic and pyrogenic properties, histological investigation (in mice, rats and rabbits) of obtained PBF was carried out. RESULTS The acute toxicity study showed that PBF is much less toxic in equivalent PTX-content doses than PTX in conventional formulation when administered intraperitoneally to mice and rats. However, the chronic toxicity study showed that at intraperitoneal administration PBF has distinct cumulative properties and toxic effects that prevent PBF from clinical testing in current composition. CONCLUSION Thus, the PBF as a prolong drug needs to correct its parameters for further drug formulation development.

New poly(3-hydroxybutyrate) microparticles with paclitaxel sustained release for intraperitoneal administration.

BACKGROUND Poly(hydroxyalkanoates) (PHA) have recently attracted increasing attention due to their biodegradability and high biocompatibility, which makes them suitable for the development of new prolong drug formulations. OBJECTIVE This study was conducted to develop new prolong paclitaxel (PTX) formulation based on poly(3- hydroxybutyrate) (PHB) microparticles. METHOD PHB microparticles loaded with antitumor cytostatic drug PTX were obtained by spray-drying method using Nano Spray Dryer B-90. The PTX release kinetics in vitro from PHB microparticles and their cytotoxity on murine hepatoma cell line MH-22a were studied. Microparticles antitumor activity in vivo was studied using intraperitoneally (i.p.) transplanted tumor models: murine Lewis lung carcinoma and xenografts of human breast cancer RMG1. RESULTS Uniform PTX release from PHB-microparticles during 2 months was observed. PTX-loaded PHB microparticles have demonstrated a significant antitumor activity versus pure drug both in vitro in murine hepatoma cells and in vivo when administered i.p. to mice with murine Lewis lung carcinoma and xenografts of human breast cancer RMG1. CONCLUSION The developed technique of PTX sustained delivery from PHB-microparticles has therapeutic potential as prolong anticancer drug formulation.

Low molecular weight poly(3-hydroxybutyrate) microparticles synthesized by piezoelectric spray drying for the sustained release of paclitaxel

Biocompatible and biodegradable polymer microparticles are contemporary medicines able to eliminate the side effects and unsatisfactory pharmacokinetics of already existing preparations. In this work we have developed a high-tech scalable method for the synthesis of paclitaxel-loaded poly(3-hydroxybutyrate) (PHB)-based microparticles. These particles were synthesized on a B-90 Buchi nano spray dryer by piezoelectric spray drying in an inert atmosphere. A regular spherical shape, narrow size distribution, and satisfactory results for the release of paclitaxel from the polymeric matric of microparticles in vitro make this polymeric medicinal form promising for its further application in pharmaceutics. Nanoparticles with a similar composition synthesized via the laboratory one-stage emulsification method were used for comparison. This study is the first stage in the creation of a sustained-action anticancer paclitaxel preparation.

Evaluation of eliciting activity of peptidil prolyl cys/trans isomerase from Pseudonomas fluorescens encapsulated in sodium alginate regarding plant resistance to viral and fungal pahogens

Use of chemical pesticides poses a threat for environment and human health, so green technologies of crop protection are of high demand. Some microbial proteins able to activate plant defense mechanisms and prevent the development of resistance in plant pathogens, may be good alternative to chemicals, but practical use of such elicitors is limited due to need to protect them against adverse environment prior their delivery to target receptors of plant cells. In this study we examined a possibility to encapsulate heat resistant FKBP-type peptidyl prolyl cis-trans isomerase (PPIase) from Pseudomonas fluorescens, which possesses a significant eliciting activity in relation to a range of plant pathogens, in sodium alginate microparticles and evaluated the stability of resulted complex under long-term UV irradiation and in the presence of proteinase K, as well as its eliciting activity in three different “plant-pathogen” models comparing to that of free PPIase. The obtained PPIase-containing microparticles consisted of 70% of sodium alginate, 20% of bovine serum albumin, and 10% of PPIase. In contrast to free PPIase, which lost its eliciting properties after 8-h UV treatment, encapsulated PPIase kept its eliciting ability unchanged; after being exposed to proteinase K, its eliciting ability twice exceeded that of free PPIase. Using “tobacco-TMV”, “tobacco-Alternaria longipes”, and “wheat-Stagonospora nodorum” model systems, we showed that encapsulation process did not influence on the eliciting activity of PPIase. In the case of the “wheat-S. nodorum” model system, we also observed a significant eliciting activity of alginate-albumin complex and almost doubled activity of encapsulated PPIase as compared to the free PPIase. As far as we know, this is the first observation of a synergistic interaction between alginate and other compound possessing any bioactive properties. The results of the study show some prospects for a PPIase use in agriculture.