R. Yu. Kosenko

Structure and prolonged transport in a biodegradable poly(R-3-hydroxybutyrate)-drug system

In order to create new biodegradable systems for the targeted transport of drugs, poly(3-hydroxy-butyrate) films containing the antibiotic rifampicin in an amount of 5–15 wt % as a model drug are prepared. Film surfaces are studied via scanning electron microscopy, and various structural elements (globules and fibrils) are found. Polymer samples isolated from melt or solution feature different degrees of porosity. It is shown that the kinetic profiles of rifampicin release are of an abnormal character. An analysis of the profiles shows that the release of rifampicin is controlled by the superposition of two processes: its desorption via the diffusion mechanism (the nonlinear segment) and hydrolytic degradation of poly(3-hydroxybutyrate) (the extended linear segment), which becomes well defined after completion of the diffusion stage. The diffusionkinetic model of the process is developed.

Development of a biodegradable polyhydroxybutyrate-chitosan-rifampicin composition for controlled transport of biologically active compounds

60 The development of therapeutic systems for pro longed and targeted transport of biologically active compounds is a topical task but a challenge for practi cal implementation. Extensive studies of polymeric dosage forms [1] provided two basic conclusions: first, at the micro and nanolevels, most beneficial are the biodegradable polymeric systems whose molecules are destroyed to give nontoxic intermediate or final prod ucts [2]; second, the search for polymer carriers requires the use of blend compositions provided that their physicochemical and transport characteristics are superior to these characteristics of the initial poly mers [3].

Magnetic and transport properties of magneto-anisotropic nanocomposites for controlled drug delivery

Biodegradable polymeric film composites consisting of chitosan (Cht) and poly(3-hydroxybutyrate) (PHB) have been produced and used to encapsulate colloidal magnetite nanoparticles (MNPs) and a drug (dipyridamole). The magnetic organization of the MNPs induced by the exposure of the films to external magnetic fields was analyzed using ferromagnetic resonance and electron microscopy. A calculation of the relative abundance of aggregated nanoparticles showed that more than 14% of the particles were aggregated at total particle concentrations ranging from 3 to 8 mass %. Modification of the PHB-Cht composite matrix by nanoparticles has been proven to evoke changes in drug release kinetics, since the particles formed ordered magneto-anisotropic structures when exposed to external magnetic fields. The highest rate of transfer by diffusion was observed in the case of a nonisotropic matrix in which the orientation of particle aggregates coincided with the direction of the diffusion flux; the rate of drug release was the lowest in anisotropic matrices of biodegradable magneto-anisotropic nanocomposites with particle orientation perpendicular to the direction of diffusion. The physical reasons for the dependence of the release kinetics on the magnetic anisotropy of the samples are discussed. The results of the present study are indicative of the possibility of creating a new generation of therapeutic systems for the targeted delivery and sustained release of drugs controlled by a magnetic field.

Influence of the film forming procedure on the interaction in polyhydroxybutyrate-polyurethane blends

The structural features of polymeric composites based on polyhydroxybutyrate and segmented polyurethane were studied. A study by the methods of H-D exchange and IR spectroscopy revealed no intermolecular interaction between polyhydroxybutyrate and polyurethane in the blends prepared using a single solvent. The interaction of the polymers is observed when using two solvents and performing high-temperature heat treatment.

Diffusion model of protein adsorption and effect of protein layer composition on water permeability for ultrafiltration membranes

Abstract The study of interrelation between kinetics of protein adsorption and flux of water through ultrafiltration membranes is of interest for understanding the influence of adsorption on ultrafiltration. A short model sketch of protein adsorption derived from complicated transport phenomena is presented. As quantitative criterion of protein adsorption the ratio of reversibility is proposed. This ratio describes the relative amount of adsorbed proteins that are reversibly arranged on the polymer surface. Ratio reversibility depends on chemical structure of membranes in sequence: polysulfone

Morphology and transport in biodegradable polymer compositions based on poly(3-hydroxybutyrate) and polyamide 54C

Complex investigation of the equilibrium sorption of water, diffusive transport of antiseptic, and morphology of mixed compositions based on polyoxybutirate and polyamide resin 54C has been performed to develop and analyze new biodegradable polymer compositions for controlled release of medicinal substances. Samples of mixtures were prepared by two methods: pressing under pressure and solvent evaporation from a polymer solution. The samples were compared and their morphology was analyzed by scanning electron microscopy. It is shown that the component ratio in the obtained mixtures affects their morphological, transport, and sorption characteristics.

Controlled release of antiseptic drug from poly(3-hydroxybutyrate)-based membranes. combination of diffusion and kinetic mechanisms

A polymeric system based on biocompatible and biodegradable poly(3-hydroxybutyrate) (PHB) is proposed for controlled release of furacilin (Frc). The kinetics of Frc release from PHB membranes containing 0.5–5.0 wt% Frc into a model aqueous medium at 25°C have been studied using a UV spectroscopy technique. The drug release profiles present a combination of diffusion and kinetic components. The diffusion component of the release kinetics has been analyzed and the dependence of the diffusivity on the drug concentrations has been determined. The rate constant of the release kinetics depends on the Frc concentration and is related to the hydrolytic destruction of PHB. The PHB hydrolysis is most clearly demonstrated in long-term experiments (after the first week of drug release). The obtained results are useful for the development of new controlled drug delivery systems containing several drugs, which provide a combined action on tissues and organs of the organism.

Structure and properties of films based on blends of polyamide–polyhydroxybutyrate

The structure and transport and diffusion properties of film matrices based on polyamide and polyhydroxybutyrate blends obtained from solutions and melts are studied. Quantitative analysis of the diffusion and sorption of water shows that the dependence of the diffusion mobility of water increases exponentially with increasing content of polyamide as the more hydrophilic component of the system. The developed materials are recommended for the creation of new therapeutic systems of controlled release of drugs.

Effect of scaling factors on the kinetics of drug release from polyhydroxybutyrate-based film systems

The effect of various scale factors, such as the molecular weight of the polymer and the film thickness, on the kinetics of the release of drugs from polyhydroxybutyrate-based film systems is studied. Changes in the structure of the films undergoing hydrolytic degradation in biological environments are observed. It is found that, with increasing molecular weight and film thickness, the release of drugs from film matrices slows down.

Diffusive transport of drugs from film matrices

The diffusion characteristics of poly(3-hydroxybutyrate)-based matrices for controlled release of an antiseptic (furacilin) are reported. The kinetics of furacilin release into aqueous solution from poly(3-hydroxybutyrate) matrices containing 0.5 to 5.0 wt % antiseptic has been investigated by UV spectrophotometry. The furacilin release curves indicate a combination of diffusion and kinetic processes. The diffusion component of the processes has been analyzed, the diffusion coefficients have been measured, and their concentration dependence has been elucidated. The release rate constant also depends on the furacilin content and is correlated with the hydrolytic degradation of the polymer.