Superhydrophobic Polyhydroxyalkanoates: Preparation and Applications.

Poly( R-3-hydroxybutyrate- co- R-3-hydroxyhexanoate) (PHBHHx), a family member of microbial polyhydroxyalkanoates (PHA), is a biodegradable and biocompatible material with some hydrophobicity and reasonable strength for packaging and tissue engineering applications. In this study, superhydrophobic PHBHHx is fabricated via a simple nonsolvent-assisted process. The material can absorb all tested hydrophobic solvents and oil up to 6-fold of the material weights from water, permitting applications for cleaning environmental oil or solvent pollutions with convenience of disposal after the usage due to its biodegradability. With an excellent combination of biodegradability and biocompatibility, superhydrophobic PHBHHx films are evaluated for antibioadhesion properities to exploit possible implant usages. Up to 100% reductions for platelet adhesions on the superhydrophobic PHBHHx surfaces are observed compared with that on the control material surfaces. Superhydrophobic biodegradable and biocompatible PHBHHx films demonstrate promising low value and high volume or high value and low volume applications.

Metabolic engineering of Escherichia coli for the synthesis of the quadripolymer poly(glycolate-co-lactate-co-3-hydroxybutyrate-co-4-hydroxybutyrate) from glucose.

Escherichia coli was metabolically engineered to effectively produce a series of biopolymers consisted of four types of monomers including glycolate, lactate, 3-hydroxybutyrate and 4-hydroxybutyrate from glucose as the carbon source. The biosynthetic route of novel quadripolymers was achieved by the overexpression of a range of homologous and heterologous enzymes including isocitrate lyase, isocitrate dehydrogenase kinase/phosphatase, glyoxylate/hydroxypyruvate reductase, propionyl-CoA transferase, ß-ketothiolase, acetoacetyl-CoA reductase, succinate semialdehyde dehydrogenase, 4-hydroxybutyrate dehydrogenase, CoA transferase and PHA synthase. In shake flask cultures using Luria-Bertani medium supplemented with glucose, the recombinant E. coli reached 7.10g/l cell dry weight with 52.60wt% biopolymer content. In bioreactor study, the final cell dry weight was 19.61g/l, containing 14.29g/l biopolymer. The structure of the produced polymer was chemically characterized by proton NMR analysis. Assessment of thermal and mechanical properties demonstrated that the quadripolymer possessed decreased crystallinity and improved toughness, in comparison to poly-3-hydroxybutyrate homopolymer. This is the first study reporting efficient microbial production of the quadripolymer poly(glycolate-co-lactate-co-3-hydroxybutyrate-co-4-hydroxybutyrate) from glucose.