Effect of collagen packing and moisture content on leather stiffness

Water-Mediated On-Demand Detachable Solid-State Adhesive of Porous Hydroxyapatite for Internal Organ Retractions

Novel adhesives for biological tissues offer an advanced surgical approach. Here, the authors report the development and application of solid-state adhesives consisting of porous hydroxyapatite (HAp) biocompatible ceramics as novel internal organ retractors. The operational principles of the porous solid-state adhesives are experimentally established in terms of water migration from biological soft tissues into the pores of the adhesives, and their performance is evaluated on several soft tissues with different hydration states. As an example of practical medical utility, HAp adhesive devices demonstrate the holding ability of porcine livers and on-demand detachability in vivo, showing great potential as internal organ retractors in laparoscopic surgery.

Spectral imaging of normal, hydrated, and desiccated porcine skin using polarized light

Significance

Spectroscopic and structural imaging of tissue layers is important for investigating tissue health. However, investigating superficial tissue is difficult using optical imaging, due to the convolved absorption and backscatter of light from deeper layers.

Aim

This report investigates the effects of hydration and desiccation of ex vivo porcine skin on the reflectance of polarized light at different wavelengths (light-emitting diodes).

Approach

We developed a spectroscopic polarized imaging system to investigate submicron changes in tissue structures. By separating polarized from depolarized backscattered light, submicron structural changes in subsurface and deeper tissue layers can be separated and monitored.

Results

The results demonstrate that (1) polarized light reflectance is about 2%, consistent with ∼6 scattering events, on average; (2) there was little wavelength dependence to the reflectance of polarized light; (3) increased hydration leads to a modest increase in total reflectance (from 0.8 to 0.9), whereas desiccation had little effect; however, hydration did not affect polarized reflectance, but desiccation slightly lowered polarized reflectance.

Conclusions

Higher scattering from the reticular dermis was likely due to swelling of collagen fiber bundles in the dermal layers, which increased fibril spacing. The epidermal skin surface showed little change due to the stratum corneum resisting desiccation and maintaining hydration.

Current Update of Collagen Nanomaterials-Fabrication, Characterisation and Its Applications: A Review

Tissue engineering technology is a promising alternative approach for improvement in health management. Biomaterials play a major role, acting as a provisional bioscaffold for tissue repair and regeneration. Collagen a widely studied natural component largely present in the extracellular matrix (ECM) of the human body. It provides mechanical stability with suitable elasticity and strength to various tissues, including skin, bone, tendon, cornea and others. Even though exogenous collagen is commonly used in bioscaffolds, largely in the medical and pharmaceutical fields, nano collagen is a relatively new material involved in nanotechnology with a plethora of unexplored potential. Nano collagen is a form of collagen reduced to a nanoparticulate size, which has its advantages over the common three-dimensional (3D) collagen design, primarily due to its nano-size contributing to a higher surface area-to-volume ratio, aiding in withstanding large loads with minimal tension. It can be produced through different approaches including the electrospinning technique to produce nano collagen fibres resembling natural ECM. Nano collagen can be applied in various medical fields involving bioscaffold insertion or fillers for wound healing improvement; skin, bone, vascular grafting, nerve tissue and articular cartilage regeneration as well as aiding in drug delivery and incorporation for cosmetic purposes.

Bovine Meniscus Middle Zone Tissue: Measurement of Collagen Fibril Behavior During Compression

BACKGROUND

Type I collagen is the major component of the extracellular matrix of the knee's meniscus and plays a central role in that joint's biomechanical properties. Repair and reconstruction of tissue damage often requires a scaffold to assist the body to rebuild. The middle zone of bovine meniscus is a material that may be useful for the preparation of extracellular matrix scaffolds.

METHODS

Here, synchrotron-based small-angle X-ray scattering (SAXS) patterns of bovine meniscus were collected during unconfined compression. Collagen fibril orientation, D-spacing, compression distance and force were measured.

RESULTS

The collagen fibrils in middle zone meniscal fibrocartilage become more highly oriented perpendicular to the direction of compression. The D-spacing also increases, from 65.0 to 66.3 nm with compression up to 0.43 MPa, representing a 1.8% elongation of collagen fibrils perpendicular to the compression.

CONCLUSION

The elasticity of the collagen fibrils under tension along their length when the meniscus is compressed, therefore, contributes to the overall elastic response of the meniscus only under loads that exceed those likely to be experienced physiologically.

Data on collagen structures in leather with varying moisture contents from small angle X-ray scattering and three point bend testing

The data presented in this article are related to the research article entitled "Effect of collagen packing and moisture content on leather stiffness" (Kelly et al., 2018). This article describes how moisture content affects collagen packing and leather stiffness. Structural changes were experimentally introduced into ovine leather through biaxial strain during tanning (׳stretch tanning׳). Leather samples produced normally without strain (׳non-stretch tanned׳) and those produced by stretch tanning, were conditioned in a range of relative humidity environments and then analysed by small angle X-ray scattering and three point bend testing. The collagen D-spacing, lateral intermolecular spacing and flexural properties were measured under these varying moisture contents.