Microparticles made from degradable polyhydroxyalkanoates of different chemical compositions a homopolymer of 3-hydroxybutyric acid, copolymers of 3-hydroxybutyric and 4-hydroxybutyric acids (P3HB/4HB), 3-hydroxybutyric and 3-hydroxyvaleric acids (P3HB/3HV), 3-hydroxybutyric and 3-hydroxyhexanoic acids (P3HB/ 3HHx) were prepared using the solvent evaporation technique, from double emulsions. The study addresses the influence of the chemical compositions on the size and npotential of microparticles. P3HB microparticles loaded with doxorubicin have been prepared and investigated. Their average diameter and n-potential have been found to be dependent upon the level of loading (1, 5, and 10 % of the polymer mass). Investigation of the in vitro drug release behavior showed that the total drug released from the microparticle into the medium increased with mass concentration of the drug. In this study mouse fibroblast NIH 3T3 cells were cultivated on PHA microparticles, and results of using fluorescent DAPI DNA stain, and MTT assay showed that microparticles prepared from PHAs of different chemical compositions did not exhibit cytotoxicity to cells cultured on them and proved to be highly biocompatible. Cell attachment and proliferation on PHA microparticles were similar to those on polystyrene. The cytostatic drug encapsulated in P3HB/3HV microparticles has been proven to be effective against HeLa tumor cells.

The present study reports the herbicidal activity of metribuzin and tribenuron-methyl embedded in the degradable matrix of natural poly-3-hydroxybutyrate [P(3HB)/MET and P(3HB)/TBM]. The developed formulations were constructed as films and microgranules, which were tested against the weeds such as white sweet clover Melilotus albus and lamb's quarters Chenopodium album in the presence of soft spring wheat (Triticum aestivum, cv. Altaiskaya 70) as the subject crop for investigation. The activity was measured in laboratory scale experiments by determining the density and weight of the vegetative organs of weeds. The study was also aimed at testing the effect of the experimental formulation on the growth of wheat crop as dependent on the method of herbicide delivery. The experimental MET and TBM formulations showed pronounced herbicidal activity against the weed species used in the study. The effectiveness of the experimental formulations in inhibiting weed growth was comparable to and, sometimes, higher than that of the commercial formulations (positive control). The amount of the biomass of the wheat treated with the experimental herbicide formulations was significantly greater than that of the wheat treated with commercial formulations.

In this study, polymer-based microparticles are used to improve the therapeutic properties of ceftriaxone (CEF) and render them safer. Poly-3-hydroxybutyrate (P3HB) and poly-3-hydroxybutyrate/polyethylene glycol (P3HB-PEG)based microparticles were prepared by two methods: a double emulsification technique and spray-drying. The microparticles were characterized in terms of size and zeta potential, morphology, total drug loading and drug release. The microparticles had spherical shapes with diameters of a size range from 0.74 to 1.55 m (emulsification technique) and from 3.84 to 6.51 m (spray-drying); CEF encapsulation efficiency was around 63% and 49% for these methods respectively. The CEF release from microparticles obtained by spray-drying reached 100% after 150h, while for microparticles obtained by emulsification technique the total release of CEF did not exceed 34% after 312 h. The release profiles could be best explained by Zero order kinetics model, Higuchi and Korsmeyer-Peppas models, as the plots showed high linearity. Antibacterial activity of the microparticles was evaluated against gram-positive and gram-negative bacterial strains. In general, CEF encapsulation in polymeric microparticles preserves the therapeutic efficacy of the CEF and provides its prolonged effect.

In this study, tebuconazole (TEB)-loaded poly-3-hydroxybutyrate (P3HB)-based microparticles were developed and comprehensively characterized. TEB-loaded microparticles (10, 25, and 50%) were prepared using double emulsification technique. Encapsulation efficiency of TEB varied from 59 to 86%. As the loading amount was increased, the average diameter of microparticles increased too, from 41.3 to 71.7 µm, while zeta potential was not influenced by TEB loading, varying between -32.6 and -35.7 mV. TEB was released gradually from 10, 25, and 50% loaded particles, and over 60 days, 25, 43, and 38%, respectively, of the initially loaded amount was released. The data obtained from in vitro TEB release were fitted to different mathematical models. It was shown that the release profiles of TEB could be best explained by Zero-order, Higuchi models and Hixson-Crowell. The antifungal activity of the P3HB/TEB microparticles against phytopathogenic fungi F. moniliforme and F. solani was comparable to that of the free fungicide. Thus, hydrophobic agrochemicals (TEB) can be effectively encapsulated into P3HB microparticles to construct slow-release formulations.