Monodisperse polyhydroxyalkanoate nanoparticles as self-sticky and bio-resorbable tissue adhesives.

Monodisperse nanoparticles of biodegradable polyhydroxyalkanoates (PHAs) polymers, copolymers of 3-hydroxybutyrate (3HB) and 4-hydroxybutyrate (4HB), are synthesized using a membrane-assisted emulsion encapsulation and evaporation process for biomedical resorbable adhesives. The precise control over the diameter of these PHA particles, ranging from 100 nm to 8 µm, is achieved by adjusting the diameter of emulsion or the PHA concentration. Mechanical properties of the particles can be tailored based on the 3HB to 4HB ratio and molecular weight, primarily influenced by the level of crystallinity. These monodisperse PHA particles in solution serve as adhesives for hydrogel systems, specifically those based on poly(N, N-dimethylacrylamide) (PDMA). Semi-crystalline PHA nanoparticles exhibit stronger adhesion energy than their amorphous counterparts. Due to their self-adhesiveness, adhesion energy increases even when those PHA nanoparticles form multilayers between hydrogels. Furthermore, as they degrade and are resorbed into the body, the PHA nanoparticles demonstrate efficacy in in vivo wound closure, underscoring their considerable impact on biomedical applications.

Ecofriendly poly(3-hydroxybutyrate-co-4-hydroxybutyrate) microbeads for sanitary products.

In the past, plastic microbeads (MBs) were added to personal healthcare products to improve the cleaning and exfoliating effects, but these have been withdrawn owing to their non-degradable nature and contribution to the pollution of marine environment, especially that caused by the adsorption of persistent organic pollutants (POPs) on MBs. Therefore, natural biodegradable alternatives are being developed, but these often do not exhibit sufficient performance to replace non-degradable MBs. In this study, poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB-4HB), a biodegradable aliphatic polyester, was used to prepare MBs via melt-electrospraying. We carried out the rheological characterization of P3HB-4HB with respect to melting temperature, and the melt-electrospray process was optimized to prepare MBs having sizes similar to those of commercially available MBs. Furthermore, the adsorption properties of the P3HB-4HB MBs for POPs were investigated. Unlike commercial MBs, the P3HB-4HB MBs adsorbed significantly fewer contaminants owing to their smooth and regular surfaces. Finally, a cleansing product containing P3HB-4HB MBs was prepared to evaluate their cleaning ability, and we found that the MB-based product could remove dirt and contaminants that were not easily removed by water alone. Thus, the biodegradable P3HB-4HB MBs have great potential for use as sustainable additives for cosmetic products for skin exfoliation.