Poly((R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate-co-(R)-3-hydroxyhexanoate) is a biocompatible and biodegradable polymer produced by fermentation of genetically modified microorganisms. Poly(3-hydroxybutyric acid) (PHB) is a common polyhydroxyalkanoate (PHA), it has been widely used for food packaging, medical implants, biodegradable sutures and drug delivery systems due to its biocompatible and biodegradable properties. PHB has been investigated as drug delivery micro- and nano-carriers.