Properties of a novel quaterpolymer P(3HB/4HB/3HV/3HHx)

Preparation, characterization and evaluation of HPβCD-PTX/PHB nanoparticles for pH-responsive, cytotoxic and apoptotic properties

Paclitaxel (PTX) is a potent anticancer drug. However, PTX exhibits extremely poor solubility in aqueous solution along with severe side effects. Therefore, in this study, an inclusion complex was prepared between PTX and hydroxypropyl-β-cyclodextrin (HPβCD) by solvent evaporation to enhance the drug's solubility. The HPβCD-PTX inclusion complex was then encapsulated in poly-3-hydroxybutyrate (PHB) to fabricate drug-loaded nanoparticles (HPβCD-PTX/PHB NPs) by nanoprecipitation. The HPβCD-PTX/PHB NPs depicted a higher release of PTX at pH 5.5 thus demonstrating a pH-dependent release profile. The cytotoxic properties of HPβCD-PTX/PHB NPs were tested against MCF-7, MDA-MB-231 and SW-620 cell lines. The cytotoxic potential of HPβCD-PTX/PHB NPs was 2.59-fold improved in MCF-7 cells in comparison to free PTX. Additionally, the HPβCD-PTX/PHB NPs improved the antimitotic (1.68-fold) and apoptotic (8.45-fold) effects of PTX in MCF-7 cells in comparison to PTX alone. In summary, these pH-responsive nanoparticles could be prospective carriers for enhancing the cytotoxic properties of PTX for the treatment of breast cancer.

Biosynthesis and Properties of Sulfur-Containing Polyhydroxyalkanoates (PHAs) Produced by Wild-Type Strain Cupriavidus necator B-10646

The study addresses the growth of the wild-type strain Cupriavidus necator B-10646 and the synthesis of sulfur-containing polyhydroxyalkanoates (PHA) by this strain on media containing fructose and three different precursors (3-mercaptopropionic acid, 3',3'-dithiodipropionic acid and 3',3'-thiodipropionic acid). By varying the concentration and number of doses of the precursors added into the bacterial culture, it was possible to find conditions that ensure the formation of 3-mercaptopropionate (3MP) monomers from the precursors and their incorporation into the C-chain of poly(3-hydroxybutyrate). A series of P(3HB-co-3MP) copolymer samples with different content of 3MP monomers (from 2.04 to 39.0 mol.%) were synthesized and the physicochemical properties were studied. The effect of 3MP monomers is manifested in a certain decrease in the molecular weight of the samples and an increase in polydispersity. Temperature changes are manifested in the appearance of two peaks in the melting region with different intervals regardless of the 3MP content. The studied P(3HB-co-3MP) samples, regardless of the content of 3MP monomers, are characterized by equalization of the ratio of the amorphous and crystalline phases and have a close degree of crystallinity with a minimum of 42%, = and a maximum of 54%.

Sustainable Materials with Enhanced Mechanical Properties Based on Industrial Polyhydroxyalkanoates Reinforced with Organomodified Sepiolite and Montmorillonite

Microplastics have become one of the greatest environmental challenges worldwide. To turn this dramatic damage around, EU regulators now want to ensure that plastic itself is fully recyclable or biodegradable. The aim of the present work is to develop a biobased and biodegradable biocomposite based on commercial polyhydroxyalkanoates (PHAs) and nanoclays, with the objective of achieving a reduction of rancid odour while avoiding any loss in thermomechanical properties, thus tackling two key disadvantages of PHAs. This research aims at completely characterising the structural, thermal and mechanical behaviour of the formulations developed, understanding the compatibility mechanisms in order to be able to assess the best commercial combinations for industrial applications in the packaging and automotive sectors. We report the development of nine nanobiocomposite materials based on three types of commercial PHA matrices: a linear poly(3-hydroxybutyrate) (P3HB); two copolymers based on poly(3-hydroxybutyrate)-co-poly(4-hydroxybutyrate) (P3HB-co-P4HB); and nanoclays, which represent a different polar behaviour. Dispersion achieved is highly relevant compared with literature results. Our findings show impressive mechanical enhancements, in particular for P3HB reinforced with sepiolite modified via aminosilanes.