Poly(vinyl alcohol)-bacterial cellulose nanocomposite

Abstract

Hydrogel-bacterial cellulose nano-composite materials are created using a hydrogel and never dried bacterial cellulose fibers. Such materials are suitable for a broad range of soft tissue replacement applications. In addition controlled release of bioactive agents properties can be designed into medical devices fabricated from such composite materials.

Description

FIELD OF THE INVENTION This invention relates to composite materials formed from a hydrogel and cellulose, and more particularly the present invention relates to new types of poly(vinyl alcohol)-bacterially produced cellulose composites suitable for soft tissue replacement and controlled release. BACKGROUND OF THE INVENTION Cardiovascular disease remains the leading cause of death in the United States, accounting for nearly 1 million deaths in 1996. Of these fatalities, 50% are attributed to coronary artery disease that arises from low-density lipoprotein (LDL) cholesterol, which transport about 75% of the cholesterol. It can penetrate the artery wall where it interacts with free radicals that attack and modify its form. The resulting oxidized form of LDL triggers white blood cells in the immune system to gather at the site, forming thick substance called plaque and causing inflammation. The plaque will build up eventually constricting the walls, in the process known as atheroscle...

AI Technical Summary

Benefits of technology

In another aspect of the invention there is provided a process of producing a composite material comprising a hydrogel and cellulose, comprising the steps of synthesizing cellulose using an effective bacteria in a microbial fermentation synthesis process to give a suspension of cellulose fibers having nanometer scale cross sectional dimensions, isolating the cellulose fibers produced by the microbial fermentation process and forming an aqueous cellulose suspension of the cellulose fibers while preventing the cellulose fibers from being dried out between the time they are produced and suspended in an aqueous liquid. A mixture is formed by mixing a hydrogel material with the aqueous cellulose suspension, and heating the resulting mixture at a sufficiently high temperature for a sufficiently long period of time for the hydrogel material to dissolve into solution, thereafter solidifying the mixture to form the composite material.

The present invention also provides a composite material comprising a hydrogel and a cellulose with the composite material produced according to a method comprising the steps of synthesizing cellulose using an effective bacteria in a microbial fermentation synthesis process to give a suspension of cellulose fibers having nanometer scale cross sectional dimensions, isolating the cellulose fibers produced by the microbial fermentation process and forming an aqueous cellulose suspension of the cellulose fibers while preventing the cellulose fibers from being dried out between the time they are produced and suspended in an aqueous liquid. A mixture is then formed by mixing a hydrogel material with the aqueous cellulose suspension, and heating the resulting mixture at a sufficiently high temperature for a sufficiently long period of time for the hydrogel material to dissolve into solution, thereafter solidifying the mixture to form the composite material, the hydrogel being present in an amount from about 5% by weight to about 20% by weight and the cellulose present in a range from about 0.05% by weight to about 5% by weight, and a remainder being water.

Problems solved by technology

Their main disadvantages are the patient risk of thromboembolism due to the poor blood compatibility and flow abnormalities.

However, their major disadvantage is their limited durability, due to structural dysfunction from calcification and noncalcific tissue deterioration.

The main disadvantage is “vein graft disease”, which is the deterioration and occlusion of the vein graft due to further advancement of the patient's coronary artery disease [7, 1].

Chemical hydrogels are also not homogeneous due to clusters of molecular entanglements.

Chain loops and free chain ends also produce network defects in both physical and chemical hydrogels, and they do not contribute to the permanent network elasticity [8, 10].

However, the mechanical strength and stiffness of these PVA materials were weak and did not fully match the mechanical properties displayed by the cardiovascular tissues such as arteries and heart valves.

One of the major disadvantages of hydrogels is that when dehydrated, they are hard and brittle, but when swollen in water, they become rubbery with a very low tear and tensile strength.

This chemical treatment also has the disadvantage of altering the natural structural characteristics of cellulose [33, 31, 32].

After the lifetime of the device is reached, the composite material can be buried in the ground for waste disposal and it is eventually decomposed to protect the environment.

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