Biomaterials, water content

One of the widely used categories of polymers for biomaterials design is that of homo-or copolymers, which could generate hydrogels. Hydrogels are three-dimensional polymer networks that could swell in water without dissolution and that, due to their high water content and rubbery nature, are very similar to natural tissues and could be considered... 

Biomaterials such as natural gums are extracted from living matter. The molecules forming these biomaterials are known to be very complex in nature. Water content in biomaterials is an essential characteristic of them. The water content plays a crucial role in its physical properties like electrical conduction through it. Since these materials are either a covalent or a hydrogen bonded system they cannot be used and tested at temperatures above 120°C. It is apparent, therefore, that not all conventional methods of material characterization can be applied. Thus, as a method of material characterization, some of the conventional methods are used in a restricted way so as to retain the biomaterial characteristics. The characterization method used in the study of natural gum Arabica is summarized in the following sections. 

It may be possible to produce clinically useful biomaterials with very low protein adsorption and potentially much enhanced biocompatibility using extremely high water content, highly flexible polymers (e.g., PEG grafted to surfaces). 

Tomihata, K. and Ikada, Y., Preparation of cross-linked hyaluronic acid films of low water content. Biomaterials, 18,(3), 189,1997. 

The moisture content of the fuel is an essential combustion parameter. Peat produced directly from the bog contains 80%-95% water (counted on the total mass), which is reduced to about 50% through natural drying on the bog during summer. Biomaterials collected in forests typically have a water content around 50%, which is higher in fall and winter and lower during spring and summer. 

Furthermore, the values are dependent on frequency, temperature, water content, blood perfusion, and the status of the body. The electrical properties of tissue wiU also change under compression (Belmont et al., 2013). The difference between data from human and mammalian animal tissue is usually considered small. The biomaterial may be in vivo or ex vivo tissue, excised material from freshly killed animals, or human autopsy material obtained a day or two after death. 

Ordinary SEM is used at a pressure less than 10 Pa. However, samples with high water content, such as biomaterials and polymer gels, largely deviate from the original structure during the drying process under such vacuum. To solve this problem, the SEM that can be used at a low vacuum level has been developed [64]. In this SEM, a pressure differential is maintained by graded evacuation between the sample chamber and the... 

Despite the fact that soft tissues are made of typical hydrogels, namely high-water content gels, synthetic hydrogels are used very little as biomateiials except for use in soft contact lenses. The reasons why synthetic hydrogels are not used in implantation have been explained here. Sjmthetic hydrogels nevertheless remain useful biomaterials, depending on the application. 

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