Machiko Takigami

Hydration characteristics of the cross-linked hyaluronan derivative hylan

Abstract The ability of hylan, the formaldehyde cross-linked derivative of hyaluronan, to interact with water has been studied using differential scanning calorimetry (DSC). Three types of water can be distinguished: non-freezing, freezing-bound and free . When the water content of the system is increased, even by up to 10%, almost all the water remains in the freezing-bound state, with a ΔH value less than free water. Several metastable states of water can be detected within the structured hylan-water matrix, indicative of defects in the frozen-bound ice structure. The maximum amount of non-freezing water, intimately associated with the hydrophilic groups of hylan, corresponds to 13 mol water per disaccharide unit of the hyaluronan chain. The large capacity shown by hyaluronan entangled networks to build water into their structure could also be responsible for their unusually high viscosity and elasticity after the onset of entanglement. Such viscoelastic properties are the basis for their use in viscosupplementation of arthritic diseased joints.

8 – Fibers in medical healthcare

This chapter presents that fibers have always occupied a fundamental position in medical healthcare, by providing textiles, in the form of fibers, mono- and multi-filament yarns, woven, knitted, non-woven, and composite materials. The uses are many and varied, from the non-implantable materials, such as bandages, dressings, etc., implantable materials, such as sutures, vascular prostheses, hygiene products, such as bedding, clothing, operating room garments, wipes, etc., to the more specialized items, such as the artificial kidney. Most are disposable, but an increasing proportion of the products are reusable. The use of non-woven fiber is characterized by their ability to meet the huge variety of needs. Non-woven technology allows for continuous production with minimal intermediate stages, whereas traditional textiles may require several distinct discontinuation batch processes, for example, spinning, winding, beaming, sizing, before knitting or weaving. The process for non-woven is simple, productive, versatile, economic, and innovative. It requires only the formation of the fibrous web and then binding together of the fibers. Their versatility will surely keep the non-woven medical materials at the forefront well into the new millennium. The chapter discusses some of the developing and possible future uses fibers in medical healthcare.

9 – Developments in nanofibers for the new millennium

From the view of fiber science and technology, the organized structure found in natural fibrous materials (cotton, wool, and silk) (“fiber system”) are made up from a hierarchical structure of micro-fiber, or to use the keyword of today, the nanofiber, as the basic unit. Today, fiber-related fields develop widely in relation to the living body (bio), sugar chains, organs, environment, and IT (information). There are a vast number of structural models in nature: the cobweb, iridescence, supra-structures in the skin of tunicates, the flexibility of bamboo, leaves of plants, and the structure and functions of bio-organs. Since developments of new functionalized fibers are based on sophisticated biomimetics, the developments lead to second-dimensional functions and then on to supra-organized fibers or fibers amalgamated in third-dimensional functions to fourth-dimensional functionalized intelligent fibers. These can control environmental changes and utilize various “new system” in fiber science and its related fields. These could lead to the creation of ultra-fiber mimicking biosystems and having functions and structures better than those of the original biosystem (super-biomimetics fibers). Here, the “nanofiber” becomes important. This chapter presents the possible development of fiber technology in the 21st century by integrating different fields.

6 – Frontier of health and comfort fibers

This chapter presents the trend of development of fiber for health. From the data, each manufacturer develops items that consumers demand. For example, the top five considerations required for clothes were: (1) ecology, (2) moisture absorption/sweat absorption/refreshing coolness, (3) deodorant/antibacterial/anti-MRSA (anti-hospital infection), (4) lightweight/heat insulation, and (5) stretch. Fibers to maintain health are classified into four categories: healthcare fiber, comfort fiber, stimulus relaxation fiber, and environmental conservation fiber. In the classification, the relation among environment, health, and fiber is readily understood. Utilizing healthcare fiber has three objectives. “Making life comfortable” and “relaxation of outside stimulation” help to maintain health. The effects aimed at are sweat absorption, high water absorption, fast-drying, anti-bacterial, mold-proofing, controlling bacterial growth, insect repellent, and acarid repellent and the latter includes heat insulation, heat storage, moisture keeping, moisture absorption, refreshing coolness, moisture permeable, water repellent, deodorization, being antibacterial. Recently, fibers with complex antibacterial/deodorization functions have appeared. The chapter presents the functions required for fiber.

1 – Searching the roots of fibers

Fiber is a thin and long material with a certain level of tensile strength. New functionalities are required according to development of information science and technology, health, medical care, resources saving, energy saving, petroleum alternative energy, and global environmental conservation. This chapter describes fibers and textiles in general and identifies the scope of high-tech fibers. It presents the development prospects of the fiber industry for the next generation. It highlights the importance of fiber as materials and the expansion of advanced fiber technology into diverse industrial areas. New fibers have appeared to meet the changing social needs over the past 30 years, including super fiber, advanced composite materials, optical fiber, shingosen (ultra fine fiber), various functional fibers, comfort/healthcare fiber, etc. High-tech fiber is an expressive way to indicate that advanced science and technology have been used to produce this fiber. High performance fibers, such as the super fiber, high function fiber, which functions as a sensor and actuator, and high touch fiber, which possess a new hand-feel, as exemplified by shingosen, are examples of high-tech fiber. The chapter presents a summary of the concept of new fibers and their applications are found in diverse areas. It illustrates examples of high-tech fiber.