Tailoring length and viscosity of dynamic metallo-supramolecular polymers in solution

RSC Advances ◽  
2016 ◽  
Vol 6 (19) ◽  
pp. 15441-15450 ◽  
Author(s):  
Stefanie Martina Munzert ◽  
Guntram Schwarz ◽  
Dirk G. Kurth
Keyword(s):  
Molecular Weight ◽  
Chain Length ◽  
Coordination Polymers ◽  
Average Molecular Weight ◽  
Supramolecular Polymers ◽  
Supramolecular Coordination

We present a detailed study of metallo-supramolecular coordination polymers (MEPEs) and how to adjust their chain-length and viscosity. A model is established, which can easily be used to prepare MEPEs of desired average molecular weight.

Engineering of Stable Recombinant Bacteria for Production of Chiral Medium-Chain-Length Poly-3-Hydroxyalkanoates

1999 ◽  
Vol 65 (8) ◽  
pp. 3265-3271 ◽  
Author(s):  
Maria A. Prieto ◽  
Michele B. Kellerhals ◽  
Gian B. Bozzato ◽  
Dragan Radnovic ◽  
Bernard Witholt ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Chain Length ◽  
Expression System ◽  
Average Molecular Weight ◽  
Polydispersity Index ◽  
Recombinant Bacteria ◽  
E Coli ◽  
Medium Chain ◽  
Medium Chain Length ◽  
Pha Production

ABSTRACT In order to scale up medium-chain-length polyhydroxyalkanoate (mcl-PHA) production in recombinant microorganisms, we generated and investigated different recombinant bacteria containing a stable regulated expression system for phaC1, which encodes one of the mcl-PHA polymerases of Pseudomonas oleovorans. We used the mini-Tn5 system as a tool to constructEscherichia coli 193MC1 and P. oleovoransPOMC1, which had stable antibiotic resistance and PHA production phenotypes when they were cultured in a bioreactor in the absence of antibiotic selection. The molecular weight and the polydispersity index of the polymer varied, depending on the inducer level. E. coli 193MC1 produced considerably shorter polyesters thanP. oleovorans produced; the weight average molecular weight ranged from 67,000 to 70,000, and the polydispersity index was 2.7. Lower amounts of inducer added to the media shifted the molecular weight to a higher value and resulted in a broader molecular mass distribution. In addition, we found that E. coli 193MC1 incorporated exclusively the R configuration of the 3-hydroxyoctanoate monomer into the polymer, which corroborated the enantioselectivity of the PhaC1 polymerase enzyme.

In vitro synthesis of glycogen: the structure, properties, and physiological function of enzymatically-synthesized glycogen

Biologia ◽  
2011 ◽  
Vol 66 (3) ◽  
Author(s):  
Hideki Kajiura ◽  
Hiroki Takata ◽  
Tsunehisa Akiyama ◽  
Ryo Kakutani ◽  
Takashi Furuyashiki ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Chain Length ◽  
Large Scale ◽  
Glycogen Synthesis ◽  
Average Molecular Weight ◽  
Spherical Particles ◽  
Average Chain Length ◽  
Scale Production ◽  
In Vitro Synthesis

AbstractThis review describes a new enzymatic method for in vitro glycogen synthesis and its structure and properties. In this method, short-chain amylose is used as the substrate for branching enzymes (BE, EC 2.4.1.18). Although a kidney bean BE and Bacillus cereus BE could not synthesize high-molecular weight glucan, BEs from 6 other bacterial sources produced enzymatically synthesized glycogen (ESG). The BE from Aquifex aeolicus was the most suitable for the production of glycogen with a weight-average molecular weight (M w) of 3,000–30,000 k. The molecular weight of the ESG is controllable by changing the concentration of the substrate amylose. Furthermore, the addition of amylomaltase (AM, EC 2.4.1.25) significantly enhanced the efficiency of this process, and the yield of ESG reached approximately 65%. Typical preparations of ESG obtained by this method were subjected to structural analyses. The average chain length, interior chain length, and exterior chain length of the ESGs were 8.2–11.6, 2.0–3.3, and 4.2–7.6, respectively. Transmission electron microscopy and intrinsic viscosity measurement showed that the ESG molecules formed spherical particles. Unlike starch, the ESGs were barely degraded by pullulanase. Solutions of ESG were opalescent (milky-white and slightly bluish), and gave a reddishbrown color on the addition of iodine. These analyses revealed that ESG shares similar molecular shapes and solution properties with natural-source glycogen. Moreover, ESG had macrophage-stimulating activity and its activity depends on the molecular weight of ESG. We successfully achieved large scale production of ESG. ESG could lead to new industrial applications, such as in the food, chemical, and pharmaceutical fields.

scholarly journals Why Chain Length of Hyaluronan in Eye Drops Matters

Diagnostics ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 511 ◽  
Author(s):  
Wolfgang G.K. Müller-Lierheim
Keyword(s):  
Molecular Weight ◽  
Epithelial Cells ◽  
Chain Length ◽  
Ocular Surface ◽  
Clinical Performance ◽  
Average Molecular Weight ◽  
Tear Film ◽  
Eye Drops ◽  
Zero Shear Viscosity ◽  
Corneal Epithelial

The chain length of hyaluronan (HA) determines its physical as well as its physiological properties. Results of clinical research on HA eye drops are not comparable without this parameter. In this article methods for the assessment of the average molecular weight of HA in eye drops and a terminology for molecular weight ranges are proposed. The classification of HA eye drops according to their zero shear viscosity and viscosity at 1000 s−1 shear rate is presented. Based on the gradient of mucin MUC5AC concentration within the mucoaqueous layer of the tear film a hypothesis on the consequences of this gradient on the rheological properties of the tear film is provided. The mucoadhesive properties of HA and their dependence on chain length are explained. The ability of HA to bind to receptors on the ocular epithelial cells, and in particular the potential consequences of the interaction between HA and the receptor HARE, responsible for HA endocytosis by corneal epithelial cells is discussed. The physiological function of HA in the framework of ocular surface homeostasis and wound healing are outlined, and the influence of the chain length of HA on the clinical performance of HA eye drops is illustrated. The use of very high molecular weight HA (hylan A) eye drops as drug vehicle for the next generation of ophthalmic drugs with minimized side effects is proposed and its advantages elucidated. Consequences of the diagnosis and treatment of ocular surface disease are discussed.

First GPC results of terpyridine based chain extended supramolecular polymers: comparison with viscosity and analytical ultracentrifugation

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
Michael A. R. Meier ◽  
Harald Hofmeier ◽  
Caroline H. Abeln ◽  
Christos Tziatzios ◽  
Mircea Rasa ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Analytical Ultracentrifugation ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Supramolecular Polymers ◽  
Supramolecular Polymer ◽  
Poly Ethylene ◽  
A Chain ◽  
First Time ◽  
Good Agreement

AbstractThe molecular weight of an extended metallo-supramolecular polymer, based on a α,ω-bis-terpyridine-poly(ethylene glycol) polymer linked via ruthenium(II) ions, was determined by gel permeation chromatography, viscosimetry as well as analytical ultracentrifugation. An optimized GPC method was applied for the first time to this kind of chain extended supramolecular polymers and the obtained results showed a good agreement with viscosimetry and analytical ultracentrifugation. A chain extended polymer with an average molecular weight of around 140 000 was found. These results clearly demonstrate that well-soluble high-molecular-weight metal-containing coordination polymers that are based on well-defined telechelics can be synthesized and fully characterized.

THE DEGRADATION OF POLYSTYRENE: II. THE SYNTHESIS AND DEGRADATION OF POLYSTYRENE POSSESSING THE KUHN–SCHULZ CHAIN LENGTH DISTRIBUTION

1950 ◽  
Vol 28b (7) ◽  
pp. 416-428
Keyword(s):  
Molecular Weight ◽  
Benzoyl Peroxide ◽  
Chain Length ◽  
Average Molecular Weight ◽  
Length Distribution ◽  
Chain Scission ◽  
Limited Range ◽  
Number Average Molecular Weight ◽  
Chain Length Distribution ◽  
Synthesis And Degradation

By polymerizing styrene in emulsion it was possible to synthesize polystyrenes of known number average molecular weight, the chain length distributions of which corresponded closely to the Kuhn–Schulz relation Ny = N0py−1(1 − p)2. This enabled a relation between intrinsic viscosity and number average molecular weight to be established for polystyrenes with chain length distributions of this functional form. Assuming this form of chain length distribution to remain unaltered on degradation, it was possible to estimate the average number of scission points per structural unit from viscosimetric measurements. The extent of thermal scission of polystyrene after one week at 144 °C. was shown to be negligible while benzoyl peroxide caused appreciable chain scission at 80 °C. and 100 °C. The number of scission points estimated from viscosimetric measurements was directly proportional to the mass of benzoyl peroxide added to the system, and the scission appeared to be essentially random over the limited range investigated.

scholarly journals Fructose-Based Production of Short-Chain-Length and Medium-Chain-Length Polyhydroxyalkanoate Copolymer by Arctic Pseudomonas sp. B14-6

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1398
Author(s):  
Tae-Rim Choi ◽  
Ye-Lim Park ◽  
Hun-Suk Song ◽  
Sun Mi Lee ◽  
Sol Lee Park ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Chain Length ◽  
Average Molecular Weight ◽  
Short Chain ◽  
Pha Synthase ◽  
Pseudomonas Sp ◽  
Short Chain Length ◽  
Medium Chain ◽  
Medium Chain Length ◽  
Pha Production

Arctic bacteria employ various mechanisms to survive harsh conditions, one of which is to accumulate carbon and energy inside the cell in the form of polyhydroxyalkanoate (PHA). Whole-genome sequencing of a new Arctic soil bacterium Pseudomonas sp. B14-6 revealed two PHA-production-related gene clusters containing four PHA synthase genes (phaC). Pseudomonas sp. B14-6 produced poly(6% 3-hydroxybutyrate-co-94% 3-hydroxyalkanoate) from various carbon sources, containing short-chain-length PHA (scl-PHA) and medium-chain-length PHA (mcl-PHA) composed of various monomers analyzed by GC-MS, such as 3-hydroxybutyrate, 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, 3-hydroxydodecenoic acid, 3-hydroxydodecanoic acid, and 3-hydroxytetradecanoic acid. By optimizing the PHA production media, we achieved 34.6% PHA content using 5% fructose, and 23.7% PHA content using 5% fructose syrup. Differential scanning calorimetry of the scl-co-mcl PHA determined a glass transition temperature (Tg) of 15.3 °C, melting temperature of 112.8 °C, crystallization temperature of 86.8 °C, and 3.82% crystallinity. In addition, gel permeation chromatography revealed a number average molecular weight of 3.6 × 104, weight average molecular weight of 9.1 × 104, and polydispersity index value of 2.5. Overall, the novel Pseudomonas sp. B14-6 produced a polymer with high medium-chain-length content, low Tg, and low crystallinity, indicating its potential use in medical applications.

A study of the effect of pyridine linkers on the viscosity and electrochromic properties of metallo-supramolecular coordination polymers

2018 ◽  
Vol 6 (13) ◽  
pp. 3310-3321 ◽  
Author(s):  
Sandesh Pai ◽  
Marco Schott ◽  
Lukas Niklaus ◽  
Uwe Posset ◽  
Dirk G. Kurth
Keyword(s):  
Coordination Polymers ◽  
Supramolecular Polymers ◽  
Electrochromic Properties ◽  
Supramolecular Coordination ◽  
Self Assembled

We present the optical, electrochemical, and electrochromic properties of Fe(ii)-, Co(ii)- and Ru(ii)-based metallo-supramolecular polymers (MEPEs) self-assembled from rigid, π-conjugated bis-terpyridines with different numbers of pyridine linkers.

The Structure of Radiation Cross-Linked Poly (ethylene oxide) Gels

1971 ◽  
Vol 29 ◽  
pp. 76-77
Author(s):  
C. E. Cluthe ◽  
G. G. Cocks
Keyword(s):  
Molecular Weight ◽  
Ethylene Oxide ◽  
Parallel Plate ◽  
Average Molecular Weight ◽  
Radical Reaction ◽  
Free Radical Reaction ◽  
Nitrogen Gas ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Initial Viscosity

Aqueous solutions of a 1 weight-per cent poly (ethylene oxide) (PEO) were degassed under vacuum, transferred to a parallel plate viscometer under a nitrogen gas blanket, and exposed to Co60 gamma radiation. The Co60 source was rated at 4000 curies, and the dose ratewas 3.8x105 rads/hr. The poly (ethylene oxide) employed in the irradiations had an initial viscosity average molecular weight of 2.1 x 106.The solutions were gelled by a free radical reaction with dosages ranging from 5x104 rads to 4.8x106 rads.

Sign in / Sign up

Export Citation Format

Share Document