1 Nanomedicine, Department of Pharmacy, Faculty of Health and Medical Sciences, Københavns Universitet2 MOE Key Lab of Bioinformatics and Systems Biology, Department of Biological Science and Biotechnology, School of Life Science, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China.3 Drug Research Academy A, Drug Research Academy, Faculty of Pharmaceutical Sciences, Københavns Universitet4 unknown5 Drug Research Academy A, Drug Research Academy, Faculty of Pharmaceutical Sciences, Københavns Universitet
Poly(4-hydroxybutyrate) (P4HB) is a highly elastic polymer, whereas poly(3-hydroxypropionate) (P3HP) is a polymer with enormous tensile strength. This study aimed to biosynthesize a block copolymer consisting of soft P4HB block with a strong P3HP block to gain unique and excellent material properties. A recombinant Escherichia coli strain that produces homopolymers of P3HP and P4HB was employed for the block copolymer synthesis. When the strain was grown in the presence of 1,4-butanediol (BDO) as a 4HB precursor, P4HB block was formed. Sequential supplementation of 1,3-propanediol (PDO) as a 3HP precursor allowed the strain to produce P3HP block. Thermal, NMR, fractionation, and mechanical characterizations confirmed the resulting polymer as a block copolymer of P3HP-b-P4HB. Two block copolymers were formed from this study, including the P3HP-b-29% P4HB and P3HP-b-37% P4HB, they showed superior properties over random copolymers P(3HP-co-4HB). The block copolymers had two glass transition temperatures (Tg) and two melting temperatures (Tm). In comparison to the homopolymers P3HP and P4HB, incorporation of block microstructure resulted in the lowering of Tm, block copolymers were revealed with higher Young's modulus, yield strengths, and tension strengths much better than the previously reported random copolymers of similar compositions. Block copolymerization of P3HP and P4HB adds a new vision on PHA polymerization by generation of new polymers with superior properties.
Biomacromolecules, 2013, Vol 14, Issue 3, p. 862-70
Butylene Glycols; Escherichia coli; Magnetic Resonance Spectroscopy; Molecular Weight; Polyesters; Polymers; Propylene Glycols; Temperature