Two distinct β-sheet fibrils from silk protein

Gong, Zuguang; Huang, Lei; Yang, Yuhong; Chen, Xin; Shao, Zhengzhong

doi:10.1039/b914218e

Cited by 96 publications

(107 citation statements)

References 33 publications

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“…[74,75]. Our results strongly suggest that macroscopic shear force or sonication may play a similar role of stretching as observed in our system, providing an extended conformational state, a template for further nucleation growth and thus amyloid assembly.…”

Section: Discussionsupporting

confidence: 79%

Direct Observation of Amyloid Nucleation under Nanomechanical Stretching

et al. 2013

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Self-assembly of amyloid nanofiber is associated with functional and pathological processes such as in neurodegenerative diseases. Despite intensive studies, stochastic nature of the process has made it difficult to elucidate molecular mechanisms for the key amyloid nucleation. Here, we investigated the amyloid nucleation of silk-elastinlike peptide (SELP) using time-lapse lateral force microscopy (LFM). By repeated scanning a single line on a SELP-coated mica surface, we observed sudden stepwise height increases, corresponds to nucleation of an amyloid fiber. The lateral force profiles followed either a worm-like chain model or an exponential function, suggesting that the atomic force microscopy (AFM) tip stretches a single or multiple SELP molecules along the scanning direction, serves as the template for further selfassembly perpendicular to the scan direction. Such mechanically induced nucleation of amyloid fibrils allows positional and directional control of amyloid assembly in vitro, which we demonstrate by generating single nanofibers at predetermined nucleation sites.

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Section: Discussionsupporting

confidence: 79%

Direct Observation of Amyloid Nucleation under Nanomechanical Stretching

et al. 2013

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Section: Fibrillar Network Of Rsf/hpmc9 Hydrogelsmentioning

confidence: 99%

“…[ 34 ] Hereby, the TEM and ScanAsyst mode AFM were primarily used to determine the morphology of RSF after the formation of the RSF/HPMC9 hydrogel. The images showed that RSF fi brils randomly distributed in hydrogel with the width of about 10 nm at the very beginning stage of incubation (in sol state) ( Figure 4 Compared to the previous report, [ 34 ] the RSF/HPMC9 hydrogel possessed a much smaller aggregates of fi brillar network than that of the alcohol-induced RSF hydrogel. Furthermore, such a relatively even fi brillar network may greatly benefi t the mechanical properties of RSF/HPMC9 hydrogel, because recent report have suggested that the formation of fi bril bundles could strengthen their mutual interactions, and thus contributed to the enhancement of the mechanical performance of hydrogel.…”

Section: Fibrillar Network Of Rsf/hpmc9 Hydrogelsmentioning

confidence: 99%

Physically Crosslinked Biocompatible Silk‐Fibroin‐Based Hydrogels with High Mechanical Performance

Luo

Yang

Shao

2015

Adv Funct Materials

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186

174

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have indeed shown greater mechanical performance than the traditional hydrogels. [8][9][10][11][12][13] However, problems still remained in terms of the applications of these hydrogels in biomedical fi elds. First, even if the elasticity of these hydrogels is improved signifi cantly, the modulus is far worse to meet the needs. Beyond that, poor biocompatibility as well as the possible toxicity of degradation product of these hydrogels poses a potential risk for the health of living beings. [ 6,7,14 ] Natural polymers, such as agarose, gelatin, hyaluronic acid and silk, possessing good biocompatibility, and the nontoxic degradation products, have received increasing interest in biomedical fi elds in the past decades. [ 15 ] Although these natural polymer based hydrogels have been extensively studied as the potential matrix for tissue engineering, the poor mechanical performance of the natural polymer based hydrogels is still a major limitation or a disadvantage for their medical applications. [ 16 ] Therefore, many methods were employed to improve the mechanical properties of the natural polymer based hydrogels. Chemical crosslinking was used as a facile routine approach to boost the mechanical properties of the natural polymer based hydrogels, but the safety of the chemical crosslinking reagent involved was a primary concern and the use of that might cause some unfavorable problems. [ 14 ] Besides chemical crosslinking, other efforts such as physical treatments [ 17,18 ] or mixing with other natural/synthetic polymers, [ 15,19 ] have been made to strengthen the natural polymer based hydrogels, yet the problem is still no closer to be solved.Among all natural polymers, Bombyx mori silk fi broin (SF) is one of the ideal candidates for biomedical applications due to it combining suffi cient mechanical performance, biocompatibility, and biodegradability. [20][21][22][23][24] Many approaches were employed to fabricate the physically crosslinked silk based hydrogels, such as sonication, vortex, addition of ethanol, and electrical fi eld. [25][26][27][28][29] However, most of the SF based hydrogels show poor mechanical performance which is a major stumbling block for applications. Recently, though a new covalently crosslinked SF based hydrogel with signifi cant elasticity was engineered via a kind of bio-crosslink reagent, i.e., HRP (horseradish peroxide), [ 7 ] it still could not escape the fate of poor mechanical properties in terms of the softness. Besides, the formation of the heterogeneous aggregates of crosslinking sites in the process of gelation can result in the poor optical properties Physically Crosslinked Biocompatible Silk-Fibroin-Based Hydrogels with High Mechanical PerformanceKunyuan Luo , Yuhong Yang , and Zhengzhong Shao * Developing hydrogel which combines superior mechanical performance and biocompatibility attracts researchers' attention in recent years. Here, a novel biocompatible hydrogel with excellent mechanical performance, comprised of regenerated silk fi broin (RSF) and hydroxypropyl methyl ce...

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“…However, when alcohol is used to trigger assembly (without shear), there emerge entangled amyloid-like nanofibers with a 'cross-β' structural feature. 15 This structural variation implies that fibroin has an incredibly flexible and moldable structure, which senses the exterior conditions and undergoes conformational transitions accordingly. One essential step in silk spinning is the reduction of pH from the posterior part of the silk gland to the anterior part of the silk gland, which triggers the gelation of the condensed fibroin.…”

Section: Introductionmentioning

confidence: 99%