Biodegradation of waste PET: A sustainable solution for dealing with plastic pollution.

The discovery of Ideonella sakaiensis, a plastic-degrading bacterium, creates possibilities for a sustainable "bioeconomy" for recycling plastic waste.

Ring-Opening Polymerization of a New Diester Cyclic Dimer of Mandelic and Glycolic Acid: An Efficient Synthesis Method for Derivatives of Amorphous Polyglycolide with High T.

In this study, poly(mandelate-co-glycolate) (PMG), a modified polyglycolide (PGL), is prepared by ring-opening polymerization (ROP) of L-3-phenyl-1,4-dioxane-2,5-dione (PDD); the cyclic dimer of biobased mandelic acid and glycolic acid. The resulting polymer shows an increased glass transition temperature (T ) due to the incorporation of phenyl groups in the chain. High molecular weight PMG is obtained by bulk ROP at 150 °C, and it exhibits a glassy amorphous state with enhanced thermal properties such as a T being 35 °C higher than conventional PGL.

Vascular induction and cell infiltration into peptide-modified bioactive silk fibroin hydrogels.

In hydrogel-based soft tissue engineering, vascular induction into a hydrogel as well as long-term volume retention is essential to maintain tissue shape and function without causing necrosis in the deeper part of the hydrogel. A silk fibroin (SF) hydrogel shows a sufficiently high mechanical strength to maintain its shape during implantation for a month, but it has not been well evaluated whether it has vascular-inducing bioactivity to achieve its replacement by vascularized tissues. Here, we produced a vascular-inducing peptide (VIP) containing an endothelial cell (EC)-adhesive REDV and vascular endothelial growth factor-mimicking QK peptides to modify the SF hydrogel.

Effect of Thermoresponsive Poly(L-lactic acid)-poly(ethylene glycol) Gel Injection on Left Ventricular Remodeling in a Rat Myocardial Infarction Model.

Some gel types have been reported to prevent left ventricular (LV) remodeling in myocardial infarction (MI) animal models. In this study, we tested biodegradable thermoresponsive gels. Poly(L-lactic acid)-poly(ethylene glycol) (PLLA-PEG) and poly(D-lactic acid)-poly(ethylene glycol) (PDLA-PEG) were synthesized by the polycondensation of l- and D-lactic acids in the presence of PEG and succinic acid.

Response to Comment on "A bacterium that degrades and assimilates poly(ethylene terephthalate)".

Yang et al suggest that the use of low-crystallinity poly(ethylene terephthalate) (PET) exaggerates our results. However, the primary focus of our study was identifying an organism capable of the biological degradation and assimilation of PET, regardless of its crystallinity. We provide additional PET depolymerization data that further support several other lines of data showing PET assimilation by growing cells of Ideonella sakaiensis.

A bacterium that degrades and assimilates poly(ethylene terephthalate).

Poly(ethylene terephthalate) (PET) is used extensively worldwide in plastic products, and its accumulation in the environment has become a global concern. Because the ability to enzymatically degrade PET has been thought to be limited to a few fungal species, biodegradation is not yet a viable remediation or recycling strategy. By screening natural microbial communities exposed to PET in the environment, we isolated a novel bacterium, Ideonella sakaiensis 201-F6, that is able to use PET as its major energy and carbon source.

Tissue-engineered acellular small diameter long-bypass grafts with neointima-inducing activity.

Researchers have attempted to develop efficient antithrombogenic surfaces, and yet small-caliber artificial vascular grafts are still unavailable. Here, we demonstrate the excellent patency of tissue-engineered small-caliber long-bypass grafts measuring 20-30 cm in length and having a 2-mm inner diameter. The inner surface of an acellular ostrich carotid artery was modified with a novel heterobifunctional peptide composed of a collagen-binding region and the integrin α4β1 ligand, REDV.

Nano-ordered surface morphologies by stereocomplexation of the enantiomeric polylactide chains: specific interactions of surface-immobilized poly(D-lactide) and poly(ethylene glycol)-poly(L-lactide) block copolymers.

Both AB diblock and ABA triblock copolymers consisting of poly(L-lactide) (PLLA: A) and poly(ethylene glycol) (PEG: B) were deposited on a silicon surface on which poly(D-lactide) (PDLA) had been preimmobilized. The deposit of the diblock copolymer (PLLA-PEG) formed band structures similar to those observed when the same copolymer was directly deposited on the silicon surface. In contrast, the deposit of the triblock copolymer (PLLA-PEG-PLLA) formed many particulates scattering over the surface.

Protecting-Group-Free Synthesis of Glycopolymers Bearing Sialyloligosaccharide and Their High Binding with the Influenza Virus.

Glycopolymers having pendant triazole-linked sialyloligosaccharides were successfully synthesized from free saccharides without any protection of the hydroxy and carboxy groups on the saccharides. The glycomonomers were synthesized by the direct azidation of free saccharides using 2-chloro-1,3-dimethylimidazolinium chloride as a condensing agent followed by copper(I)-catalyzed azide-alkyne cycloaddition. The resultant glycomonomers were copolymerized with acrylamide by a reversible addition-fragmentation chain transfer technique.

Synthesis of ABCBA penta stereoblock polylactide copolymers by two-step ring-opening polymerization of L- and D-lactides with poly(3-methyl-1,5-pentylene succinate) as macroinitiator (C): development of flexible stereocomplexed polylactide materials.

BCB triblock copolymers consisting of poly-L-lactide (PLLA: B) and poly(3-methy-1,5-pentylene succinate) (SA/MPD: C) were first synthesized by ring-opening polymerization (ROP) of L-lactide by using a dihydroxyl-terminated SA/MPD (Mn≈20k) and tin octoate as the macroinitiator and catalyst, respectively. The telechelic dihydroxyl-terminated SA/MPD was readily synthesized by the controlled melt-polycondensation of succinic acid and 3-methyl-1,5-pentandiol (MPD). The resultant triblock copolymers, dihydroxyl-terminated, were subsequently utilized as the macroinitiators in the second-step ROP of D-lactide to obtain ABCBA penta-block copolymers (penta-sb-PLA) consisting of poly-D-lactide (PDLA), PLLA, and SA/MPD as the A, B, and C blocks, respectively.

Synthesis of silyl-terminated polylactides for controlled surface immobilization of polylactide macromolecular chains.

Poly(D-lactide)s (PDLA) having an end group of trimethoxysilyl (P(x)-Si-(OMe)(3)) or monoethoxydimethylsilyl (P(x)-Si-OEt) group were synthesized to immobilize macromolecular chains of polylactide onto a flat silicon surface by the "grafting onto" mechanism. Both the end-functional PDLAs were efficiently immobilized on the flat surface of silicon wafers to create different nano-ordered structures. The P(x)-Si-OEt having the monofunctional siloxyl group formed a homogeneous dot morphology consisting of homogeneously dispersed particles of 20-30 nm in diameter while the P(x)-Si-(OMe)(3) having the trifunctional siloxyl group formed a heterogeneous morphology consisting of both spots and fibrous strands.

Highly efficient reinforcement of poly-L-lactide materials by polymer blending of a thermotropic liquid crystalline polymer.

A novel polymer blend system consisting of poly(l-lactide) (PLLA) and a thermotropic liquid crystalline polymer (LCP: an aromatic polyester comprising poly(4-hydroxybenzoate) sequences) was investigated in the presence and absence of a polycabodiimide (PCD). Scanning electron micrographs of the injection-molded polymer blends revealed the formation of fibrous structure of LCP in the PLLA matrix, supporting the efficient toughening. In particular, the LCP fibrils became semimicrometer in diameter in the presence of PCD with which both PLLA and LCP had reacted during the melt blending to form their block and graft copolymers working as compatibilizer.

Enhanced stereocomplex formation of poly(L-lactic acid) and poly(D-lactic acid) in the presence of stereoblock poly(lactic acid).

Stereoblock poly(lactic acid) (sb-PLA) is incorporated into a 1:1 polymer blend system of poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA) that has a high molecular weight to study its addition effect on the stereocomplex (sc) formation of PLLA and PDLA. The ternary polymer blend films are first prepared by casting polymer solutions of sb-PLA, PLLA, and PDLA with different compositions. Upon increasing the content of sb-PLA in the blend films the sc crystallization is driven to a higher degree, while the formation of homo-chiral (hc) crystals is decreased.

Layer-by-Layer crystallization of enantiomeric poly(lactide)s.

Poly(lactide)s stereocomplex ultrathin film with controlled structure at a molecular level was able to be prepared by stepwise assembly using the stereocomplex interaction. Pure stereocomplex crystal can be easily obtained by using this technique. When the substrates pre-coated with the stereocomplex assembly were immersed into solution of poly(L-lactide) or poly(D-lactide) for a long time, each polymer was homogeneously deposited on the substrates.

Preparation and properties of ProNectin F-coated biodegradable hollow fibers.

ProNectin F-coated biodegradable hollow fibers were newly prepared and their cytocompatibility was evaluated in vitro. Although the coating efficiency onto poly(L-lactic acid) (PLLA) and poly(lactide-co-caprolactone) [p(LA/CL)] matrices was similar, the cell adhesion properties were greatly affected by the nature of the polymer substrate. ProNectin F-coated PLLA showed about seven times higher cytocompatibility than ProNectin F-coated p(LA/CL).

Stereoblock poly(lactic acid): synthesis via solid-state polycondensation of a stereocomplexed mixture of poly(L-lactic acid) and poly(D-lactic acid).

Stereoblock poly(lactic acid) consisting of D- and L-lactate stereosequences can be successfully synthesized by solid-state polycondensation of a 1:1 mixture of poly(L-lactic acid) and poly(D-lactic acid). In the first step, melt-polycondensation of L- and D-lactic acids is conducted to synthesize poly(L-lactic acid) and poly(D-lactic acid) with a medium-molecular-weight, respectively. In the next step, these poly(L-lactic acid) and poly(D-lactic acid) are melt-blended in 1:1 ratio to allow formation of their stereocomplex.

Production of D-lactic acid by bacterial fermentation of rice starch.

D-Lactic acid was synthesized by the fermentation of rice starch using microorganisms. Two species: Lactobacillus delbrueckii and Sporolactobacillus inulinus were found to be active in producing D-lactic acid of high optical purity after an intensive screening test for D-lactic acid bacteria using glucose as substrate. Rice powder used as the starch source was hydrolyzed with a combination of enzymes: alpha-amylase, beta-amylase, and pullulanase to obtain rice saccharificate consisting of maltose as the main component.

Hydrogel formation between enantiomeric B-A-B-type block copolymers of polylactides (PLLA or PDLA: A) and polyoxyethylene (PEG: B); PEG-PLLA-PEG and PEG-PDLA-PEG.

A mixed suspension of the enantiomeric B-A-B triblock copolymers, polyoxyethylene-block-poly(L-lactide)-block-polyoxyethylene (PEG-PLLA-PEG) and polyoxyethylene-block-poly(D-lactide)-block-polyoxyethylene (PEG-PDLA-PEG), was found to induce reversible gel-to-sol transition depending on the polymer concentration and temperature. The storage and loss moduli of the gel formed at lower temperature were much higher than those of the gel prepared from the corresponding ABA-type triblock copolymers because of the higher polymer concentration in the former. Although the stereo-complexation of the PLLA and PDLA blocks occurred at higher temperature also in the B-A-B copolymers, it was not responsible for the gelation of the mixed suspension.

Composition analysis of poly(ethylene glycol)-poly(L-lactide) diblock copolymer studied by two-dimensional column chromatography.

We used two-dimensional column chromatography to analyze the composition of a sample of presumably a diblock copolymer of poly(ethylene glycol) (PEG) and poly(L-lactide) synthesized from monomethoxy-terminated PEG. The first dimension of the separation is phase fluctuation chromatography to prepare fractions that contain various components of the copolymer in different ratios. The second dimension is size-exclusion chromatography, NMR, and HPLC at the critical condition of PEG.