Structure and Mechanical Properties of Human Trichocyte Keratin Intermediate Filament Protein

Chou, C.K.; Buehler, Markus J.

doi:10.1021/bm301254u

Cited by 55 publications

(54 citation statements)

References 67 publications

(96 reference statements)

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“…Fig. 4b shows the IF formation process [28,45]: two isolated right-handed a-helix chains form a left-handed coiled-coil, the dimer (45 nm long), by disulfide cross links; then dimers aggregate end-to-end and stagger side-by-side via disulfide bonds [46] to form a protofilament (about 2 nm diameter); two protofilaments laterally associate into a protofibril; four protofibrils combine into a circular or helical IF with a diameter of 7 nm. It is clear that the IF is based on coiled-coil structure.…”

Section: Molecular Structure and Formation Of The Filamentsmentioning

confidence: 99%

“…The mechanical properties of a-keratins at the molecular scale have been studied experimentally [114,115] and through atomic simulation [46] to understand the deformation and fracture behavior. Fig.…”

Section: Two-phase Model For A-keratinmentioning

confidence: 99%

“…Fig. 13 shows the simulated tensile force-displacement curves of a heterodimer and truncated tetramers (formed by two heterodimers) [46]. When pulling the heterodimer, in the first region (I), the force increases linearly with displacement until the rupture of the hydrogen bonds and uncoiling of a-helices.…”

Section: Two-phase Model For A-keratinmentioning

confidence: 99%

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Keratin: Structure, mechanical properties, occurrence in biological organisms, and efforts at bioinspiration

Wang

Yang

McKittrick

et al. 2016

Progress in Materials Science

658

474

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a b s t r a c tA ubiquitous biological material, keratin represents a group of insoluble, usually high-sulfur content and filament-forming proteins, constituting the bulk of epidermal appendages such as hair, nails, claws, turtle scutes, horns, whale baleen, beaks, and feathers. These keratinous materials are formed by cells filled with keratin and are considered 'dead tissues'. Nevertheless, they are among the toughest biological materials, serving as a wide variety of interesting functions, e.g. scales to armor body, horns to combat aggressors, hagfish slime as defense against predators, nails and claws to increase prehension, hair and fur to protect against the environment. The vivid inspiring examples can offer useful solutions to design new structural and functional materials.Keratins can be classified as a-and b-types. Both show a characteristic filament-matrix structure: 7 nm diameter intermediate filaments for a-keratin, and 3 nm diameter filaments for b-keratin.Both are embedded in an amorphous keratin matrix. The molecular unit of intermediate filaments is a coiled-coil heterodimer and that of b-keratin filament is a pleated sheet. The mechanical response of a-keratin has been extensively studied and shows linear Hookean, yield and post-yield regions, and in some cases, a high reversible elastic deformation. Thus, they can be also be considered 'biopolymers'. On the other hand, b-keratin has not been investigated as comprehensively. Keratinous materials are strain-rate sensitive, and the effect of hydration is significant.Keratinous materials exhibit a complex hierarchical structure: polypeptide chains and filament-matrix structures at the nanoscale, Progress in Materials Science 76 (2016) 229-318 Contents lists available at ScienceDirect Progress in Materials Sciencej o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / p m a t s c i organization of keratinized cells into lamellar, tubular-intertubular, fiber or layered structures at the microscale, and solid, compact sheaths over porous core, sandwich or threads at the macroscale. These produce a wide range of mechanical properties: the Young's modulus ranges from 10 MPa in stratum corneum to about 2.5 GPa in feathers, and the tensile strength varies from 2 MPa in stratum corneum to 530 MPa in dry hagfish slime threads. Therefore, they are able to serve various functions including diffusion barrier, buffering external attack, energy-absorption, impact-resistance, piercing opponents, withstanding repeated stress and aerodynamic forces, and resisting buckling and penetration.A fascinating part of the new frontier of materials study is the development of bioinspired materials and designs. A comprehensive understanding of the biochemistry, structure and mechanical properties of keratins and keratinous materials is of great importance for keratin-based bioinspired materials and designs. Current bioinspired efforts including the manufacturing of quill-inspired aluminum composites, animal horn-inspired SiC composites, and feather-i...

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Section: Molecular Structure and Formation Of The Filamentsmentioning

confidence: 99%

Section: Two-phase Model For A-keratinmentioning

confidence: 99%

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Keratin: Structure, mechanical properties, occurrence in biological organisms, and efforts at bioinspiration

Wang

Yang

McKittrick

et al. 2016

Progress in Materials Science

658

474

View full text Add to dashboard Cite

show abstract

“…The higher the Young's modulus the higher the stiffness of the material. For keratin-based biological material other than human nails Young's moduli have been determined to range from 1-4 GPa [7]. For bovine hoofs, the material that is often used to replace human nails in drug penetration studies, this value was measured 0.4 GPa [8].…”

Section: Fig 2 Structural Formula Of a Novel Multifunctional Porphymentioning

confidence: 99%

Mechanical Properties of Healthy and ex vivo Onychomycosis Nails and the Influence of a Porphyrin-propylene Glycol Antifungal Formulation

Hosseinzoi

Galli

Incrocci

et al. 2016

BJAST

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Aims: To investigate nail penetration enhancing effectiveness of a novel drug formulation and ingredients, 40% propylene glycol (PG) and 40 µM multifunctional photosensitizer (MFPS). Proposed formulation was proven effective in photodynamic treatment (PDT) of ex vivo fungal infections of human nails (onychomycoses) and indirectly also to weaken nail's strength. Study Design: To directly proof the effect of the novel formulation on nail's hardness Atomic Force Microscopy (AFM) was employed to measure small-distance forces. Based on indentations Young's moduli of healthy and ex vivo onychomycosis nails were calculated before and after treatment with the novel formulation. Changes in young's modulus can be related to changes in nail's strength and thus formulation effectiveness. Additionally, AFM imaging was employed to study topographical / roughness changes resulting from the treatments to both nail types. Trichophyton mentagrophytes, representative for clinical onychomycosis, was chosen to induce nail infections.

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“…Besides these deformation models, previous computational studies of keratin proteins and other α-helical proteins, such as vimentin IF, focusing on the atomistic configuration and nanomechanical properties at atomistic scale have been reported [22][23][24][25][26][27] . However, relatively little is known of the basic physical material concepts that drive its deformation behavior, thus presenting an opportunity to generate a new approach that considers the structure-property paradigm from the atomistic level to the macroscopic scale.…”

Section: Introductionmentioning

confidence: 99%

Mechanics of trichocyte alpha-keratin fibers: Experiment, theory, and simulation

et al. 2015

Self Cite

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ABSTRACT:The mechanical behavior of human hair is determined by interaction of trichocyte alpha keratin protein, matrix and disulfide bonds crosslinking between alpha-keratin and matrix. Much effort has been spent to understand the link between the microscopic structure and the macroscopic fiber properties. Here we apply a mesoscopic coarse-grained model of the keratin macrofilament fibril and an analytical solution based on the concept of entropic hyperelasticity of the protein helix to investigate the link between the microscopic structure and the macroscopic properties of keratin fibres. The mesoscopic model provides good agreement with a wide range of experimental results. Based on the mesoscopic model, the predicted stress-strain curve of hair fibers agrees well with our own experimental measurements. The disulfide crosslink the microfibril-matrix and matrix-matrix contributes to the initial modulus and provides stiffening at larger deformation of trichocyte keratin fibers. The results show that the disulfide bonds reinforce the macrofilament and enhance the robustness of the macrofilament by facilitating the microfilaments to deform cooperatively. The availability of a mesoscopic model of this protein opens the possibility to further explore the relationship between microscopic chemical structure and macroscopic performance for a bottom-up description of soft materials.

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Structure and Mechanical Properties of Human Trichocyte Keratin Intermediate Filament Protein

Cited by 55 publications

References 67 publications

Keratin: Structure, mechanical properties, occurrence in biological organisms, and efforts at bioinspiration

Keratin: Structure, mechanical properties, occurrence in biological organisms, and efforts at bioinspiration

Mechanical Properties of Healthy and ex vivo Onychomycosis Nails and the Influence of a Porphyrin-propylene Glycol Antifungal Formulation

Mechanics of trichocyte alpha-keratin fibers: Experiment, theory, and simulation

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