Bioresorbable Membranes Based on Silica Gel for Healing Internal and External Wounds

Fraunhofer/DE researchers have succeeded in using the bioresorbable silica gel Renacer® to produce an electro-spun membrane that is neither cytotoxic to cells nor genotoxic. This model mimics fibrous structures found in connective tissue and is therefore particularly suitable for regenerative applications, such as for improved wound healing. The treatment of large as well as internal wounds is challenging and can be a very lengthy process. Researchers at the Fraunhofer Institute for Silicate Research ISC/DE and the Fraunhofer Institute for Toxicology and Experimental Medicine ITEM/DE have developed a bioresorbable membrane for this use. This membrane supports wound healing and biodegrades completely in the body to a natural substance.

The basis for the novel membrane is a fiber fleece developed at Fraunhofer ISC. This fleece has already been approved as a medical device to support the regeneration of chronic wounds, such as the diabetic foot. During the healing process, the material dissolves completely within 6–8 weeks. Using the electrospinning method, the researchers have now managed to reduce the 50- µm fiber diameter by a factor of more than 50, resulting in fibers with diameters of less than 1 µm. This made it possible to spin a silica gel sol into an open-meshed silica gel membrane consisting of fibers with a diameter of about 1 µm. In some cases, the diameters achieved were as small as 100 nm. “These fiber systems imitate the extracellular matrix, the fiber structures found in connective tissue, in the body and are very well tolerated by human cells for tissue regeneration. They cause no foreign body reactions and no internal scarring. The innovative silica gel membrane releases only one degradation product, ortho-silicic acid. This has a regenerative effect on the tissue and promotes the closing of wounds,” explained Dr Bastian Christ, scientist at  Fraunhofer ISC in Würzburg. Together with his colleagues, he was in charge of the synthesis and processing of the material.

Using a confocal microscope, a special light microscope, it was possible to show that the small-meshed membrane, which serves as a demonstrator, exhibits a barrier function. This prevents the passage of connective tissue cells for a period of at least seven days without interfering with cell proliferation. In addition, the membrane is resorbable, is not cyto- or genotoxic and thus causes no direct damage to tissue or DNA. The Renacer® membrane dissolves completely into almost pH neutral non-toxic ortho-silicic acid, the only water-soluble form of silica. It is physiologically present in the body and has been shown to stimulate connective skin tissue formation and bone formation. Products currently available do not exhibit such bioactive properties. Furthermore, drugs can be encapsulated into the matrix of the silica gel fibers, to be released during material resorption.


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