Polypeptide grafted hyaluronan: A self-assembling comb-branched polymer constructed from biological components

Kandadai, Madhuvanthi A.; Anumolu, Rajasekhar; Wang, Xiaojun; Baskaran, Durairaj; Pease, Leonard F.; Bedrov, Dmitry; Smith, Grant D.; Mays, Jimmy W.; Magda, Jules J.

doi:10.1016/j.eurpolymj.2011.07.017

Cited by 3 publications

(4 citation statements)

References 19 publications

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“…Below this crossover frequency, i.e., in the terminal regime, G ″ > G ′ (implying that the behavior is viscous at longer timescales); conversely, above this frequency, G ′ > G ″ (implying that the behavior is elastic at shorter timescales). Such crossing of G ′ and G ″ is the characteristic of polymer chains exhibiting molecular association into networklike structures, where the crossover frequency may be identified with the average network lifetime. , Physically this means that at timescales over which G ″ > G ′, polymer chains have sufficient time to escape from the constraints of surrounding chains, and thus show viscous behavior, while at shorter timescales, the chains are localized by surrounding chains, and the material exhibits elastic behavior. A similar viscoelastic response is observed in “entangled” polymer solutions, along with the same trend in the crossover frequency with polymer concentration. , …”

Section: Resultssupporting

confidence: 74%

“…In certain biomedical applications of the polymers considered in the present work such as vehicles for gene therapy, nanoparticle drug delivery, tissue engineering, and as a material for boosting the viscoelastic properties of the synovial fluid of the joints of patients with arthritis, the molecules are “hydrophobically modified” by grafting alkanes and other relatively hydrophobic side groups (e.g., proteins) to these polymers. Kandadai et al investigated the rheology of HA modified by isotactic poly(L-leucine) and found that its behavior indicated a weak-gel rheological response. This effect was interpreted in terms of the supramolecular polymer assembly of the hydrophobically modified chains, similarly to our interpretation of the rheological properties of aggrecan–HA solutions.…”

Section: Resultsmentioning

confidence: 99%

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Rheological Properties of Cartilage Glycosaminoglycans and Proteoglycans

2021

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Glycosaminoglycans (GAGs) are molecules that govern the load-bearing and frictional properties of cartilage and the lubricating properties of synovial fluid of joints. Most GAGs in the body form proteoglycans (PGs), and the dominant PG in cartilage is the bottlebrush-shaped aggrecan, comprised of a protein core decorated by GAG side chains consisting mainly of chondroitin sulfate (CS) and keratan sulfate. Additionally, hyaluronic acid (HA) induces aggrecan to self-assemble into complexes having up to 100 aggrecan molecules attached to each HA chain “backbone”. Here, we report the rheological properties of CS, HA, aggrecan, and aggrecan–HA complexes in water and salt solutions. We find that CS solutions are viscous liquids, while HA solutions exhibit viscoelasticity and shear thinning. Specifically, in the case of HA, the storage modulus G′ exceeds the loss modulus G″ at high frequencies (ω) while the reverse is true at low ω. Thus, the rheologies of CS and HA exhibit somewhat distinct viscoelastic properties. Aggrecan, on the other hand, shows a rheology consistent with an incipient “weak gel” in which G′ and G″ cross at a specific ω and follow a power-law scaling over a wide ω range. Moreover, aggrecan samples do not attain an observable plateau in the viscosity under steady shear and low shear rates. Finally, the complexation of aggrecan and HA over a period of 48 h results in a slow evolution (“aging”) in measured rheological properties, with G′ at low ω progressively increases in time, while G″ remains essentially unchanged. This suggests that aggrecan and HA gradually form a macroscopic network in which molecular complexes act as physical cross-links.

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Section: Resultssupporting

confidence: 74%

Section: Resultsmentioning

confidence: 99%

Rheological Properties of Cartilage Glycosaminoglycans and Proteoglycans

2021

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“…However, its crystallization has an impact on its degradation rate and affects its application. The architectural effect on properties of polymers has been studied by some groups, ,− including the architecture effect on the crystallization behavior of polymers containing PCL. − For example, Choi et al studied the crystallization of three hyperbranched PCLs as well as their linear counterparts with different lengths of homologous PCL segments and different numbers of branching points but similar molecular weights, and they found that the lengths of the linear backbone segments have a positive effect on the crystallization while the numbers of branching points bring opposite effect. Therefore, we further studied the crystallization of unfractionated HB-(PS 18 - b -PCL 28 ) n with different weight-average molar masses by POM and DSC measurements.…”

Section: Resultsmentioning

confidence: 99%

Construction and Properties of Hyperbranched Block Copolymer with Independently Adjustable Heterosubchains

Yang

Jing

et al. 2014

Macromolecules

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A trifunctional initiator with one alkyne, one hydroxyl, and one bromine group was used to construct Br-polystyrenealkyne-poly(ε-caprolactone)-OH (Br−PS−≡−PCL−OH) diblock copolymer precursor with one terminal alkyne group located at the junction between the two blocks. Further bromination and azidation substitution of the precursor led to a seesaw-type macromonomer azidepolystyrene-alkyne-poly(ε-caprolactone)-azide (N 3 −PS−≡−PCL−N 3 ). Subsequently, novel hyperbranched copolymers [HB-(PS-b-PCL) n ] with independently adjustable PS and PCL branching subchains were prepared by "click" chemistry. All of the linear precursors and hyperbranched copolymers were characterized by FT-IR, 1 H NMR, and GPC with triple detectors in detail. It was found that such hyperbranched copolymers are self-similar objects; namely, their intrinsic viscosities ([η]) are scaled to the weight-average molar masses (M w ) as [η] ∼ M w ν , where ν = 0.45 ± 0.01 and 0.48 ± 0.01 for the longer and shorter PS block, respectively. Moreover, the study on the crystallization behavior of unfractionated and fractionated HB-(PS-b-PCL) n copolymers indicated both the crystal size and the degree of crystallinity decrease with the PS subchain length and the overall degree of polymerization, and the remaining oligomer and macromonomer components could facilitate the crystallization of the unfractionated sample. Finally, it was found that the degree of crystallinity decreases dramatically when the weight fraction of fractionated hyperbranched copolymer in macromonomer/hyperbranched copolymer blend films exceeds ∼67%, indicating that the uncrystallizable hyperbranched chains may impose some extra restriction on the crystallization of the macromonomer chains.

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“…We note that in certain biomedical applications (gene therapy, nanoparticle drug delivery, tissue engineering, and as a material for boosting the viscoelastic properties of the synovial fluid of the joints of patients with arthritis), certain polymers considered in the present work (e.g., HA) have been “hydrophobically modified” by grafting alkane chains, and other relatively hydrophobic side groups (e.g., peptides) onto these molecules, which evidently enhances the formation of materials in a weak gel state. For example, Kandadai et al [ 90 ] investigated the rheology of HA modified with isotactic poly(L‐leucine) and found a rheological response consistent with weak gel formation. This viscoelastic response was interpreted in terms of the supramolecular assembly of the hydrophobically modified chains, similarly to our interpretation of the rheological properties of aggrecan−HA solutions.…”

Section: Biomedical Implications Of the Weak Gel State Of Materialsmentioning

confidence: 99%

Cartilage polymers: From viscoelastic solutions to weak gels*

Horkay

Douglas

2021

Polymer Engineering & Sci

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The dynamic properties of the polymeric components of cartilage are important for understanding the many biological functions of this biological tissue. Knowledge of the rheology of these materials is also crucial for the development of therapeutic treatments for diseases, such as arthritis, in which cartilage loses its functional physiological properties. In the present work complementary noninvasive techniques, rheology and dynamic light scattering (DLS) are used to probe the structural and dynamic properties of solutions of the principal proteoglycan components of cartilage extracellular matrix at different levels of structural hierarchy (chondroitin sulfate, aggrecan, aggrecan‐hyaluronic acid complex). It is shown that the bottlebrush shaped aggrecan molecules form large, loosely organized polyelectrolyte domains comprised of molecules organized into diffuse branched polymer network structures permeated by a diffuse cloud of counter‐ions. The rheological behaviors of these polymer solutions vary from viscoelastic solutions, consistent with the formation of dynamic polymer clusters in solution, to “weak gel” materials exhibiting approximate power law shear stress relaxation or creep over a wide range of timescales.

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Polypeptide grafted hyaluronan: A self-assembling comb-branched polymer constructed from biological components

Cited by 3 publications

References 19 publications

Rheological Properties of Cartilage Glycosaminoglycans and Proteoglycans

Rheological Properties of Cartilage Glycosaminoglycans and Proteoglycans

Construction and Properties of Hyperbranched Block Copolymer with Independently Adjustable Heterosubchains

Cartilage polymers: From viscoelastic solutions to weak gels*

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