Polyhydroxyalkanoates (PHAs) are a family of polyesters produced by many microbial species. These naturally occurring polymers are widely used in tissue engineering because of their in vivo degradability and excellent biocompatibility. The best studied among them is poly(3-hydroxybutyrate) (PHB) and its copolymer with 3-hydroxyvaleric acid (PHBV). Despite their superior properties, PHB and PHBV suffer from high crystallinity, poor mechanical properties, a slow resorption rate, and inherent hydrophobicity. Not only are PHB and PHBV hydrophobic, but almost all members of the PHA family struggle because of this characteristic. One can overcome the limitations of microbial polyesters by modifying their bulk or surface chemical composition. Therefore, researchers have put much effort into developing methods for the chemical modification of PHAs. This paper explores a rarely addressed topic in review articles—chemical methods for modifying the structure of PHB and PHBV to enhance their suitability as biomaterials for tissue engineering applications. Different chemical strategies for improving the wettability and mechanical properties of PHA scaffolds are discussed in this review. The properties of PHAs that are important for their applications in tissue engineering are also discussed.

Amphiphilic copolymers represent a primary class of stabilizers for lipid–polymer hybrid nanoparticles. Among them, lyotropic liquid crystalline nanoparticles (LLCNPs) have some significant advantages, such as controlled release, targeted delivery and protection of active compounds, towards their use as potential carriers of active substances or drugs. The aim of this work is to study a series of linear amphiphilic block copolymers for stabilization of glyceryl monooleate [1-(cis-9-octadecenoyl)-rac-glycerol]-based lipid–polymer hybrid nanoparticles. For this purpose, poly(ethylene glycol)-b-poly(benzyl 5-methyl-2-oxo-1,3-dioxane-5-carboxylate), poly(ethylene glycol)-b-poly(9,9-dimethyl-2,4,8,10-tetraoxaspiro[5.5] undecan-3-one), and poly(ethylene glycol)-b-poly(trimethylene carbonate) were synthesized using anionic ring opening polymerization and poly[oligo(ethylene glycol) methacrylate]-b-poly(ethyl methacrylate) was synthesized by atom transfer radical polymerization. The chemical structures of copolymers were confirmed by ¹H-NMR, while the molar masses were determined by SEC measurements. Lipid–polymer nanosystems were prepared by the top-down method. Their physicochemical and morphological characteristics were assessed through dynamic light scattering (DLS), cryogenic transmission electron microscopy (cryo-TEM), fast Fourier transform (FFT) analysis and microcalorimetry (mDSC). Varying the molar ratios of GMO to copolymers resulted in nanoparticles with different sizes and internal organization, with these properties being influenced by the type of hydrophobic block used in the copolymer, as can be expected and observed for other LLCNPs stabilized with amphiphilic block copolymers. This study introduces a broader group of amphiphilic polymeric stabilizers for the development of LLCNPs and highlights how variations in copolymer composition affect the structural characteristics and properties of emerging nanosystems.

Polyhydroxyalkanoates (PHAs) are a family of polyesters produced by many microbial species. These naturally occurring polymers are widely used in tissue engineering because of their in vivo degradability and excellent biocompatibility. The most well-studied among them is poly(3-hydroxybutyrate) (PHB) and its copolymer with 3-hydroxyvaleric acid (PHBV). Despite their superior properties, PHB and PHBV suffer from high crystallinity, poor mechanical properties, slow resorption rate, and inherent hydrophobicity. Not only PHB and PHBV are hydrophobic, but almost all members of the PHA family struggle because of this characteristic. One can overcome the limitations of microbial polyesters by modifying their bulk or surface chemical composition. Therefore, researchers have put much effort into developing the methods for chemical modification of PHAs. This paper reviews the chemical modification methods of PHAs that make them more suitable for scaffold fabrication. Different chemical strategies for improving the wettability and mechanical properties of the PHA scaffolds are discussed in this review. Emphasis is placed on the methods used to modify the chemical structure of PHB and PHBV, the most important polymers of the PHA family. The properties of PHAs that are important for their applications in tissue engineering are also discussed.