Exploration of Polytetrafluoroethylene as a Potential Material Replacement for Hemodialysis Applications
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Exploration of Polytetrafluoroethylene as a Potential Material Replacement for Hemodialysis Applications Patrick E. Nichols, Jeffrey S. Bates, and Taylor D. Sparks Materials Science and Engineering Department, University of Utah, 122 S. Central Campus Drive, Salt Lake City, UT 84112, USA
Abstract Dialysis is the process by which an artificial kidney device removes waste and excess water from a patient. An outstanding problem with dialysis is that the body has a remarkable immune function where proteins and antigens mark foreign objects as possible threats despite the biocompatibility of the material. Upon adhesion to polymeric materials used currently in dialysis, proteins are lost. In this study, polytetrafluoroethylene (PTFE) is investigated as a potential replacement material for dialysis tubing because of its unreactive nature. The focus is to determine if PTFE will prove a viable material in minimizing protein adhesion and further reducing antibody loss of the patient. Protein loss as a function of filtration time was measured. PVC and PTFE materials were investigated following the same battery of testing where the protein concentrations in the blood were characterized using UV Visible spectrophotometry. Results demonstrate a loss of nearly 12 percent of blood proteins to the PVC material over the course of a typical dialysis treatment. Conversely, the protein loss due to adhesion to PTFE was less than two percent.
Introduction Many patients who have kidney malfunction require dialysis, wherein a machine artificially performs some of the kidney functions.1 Dialysis removes waste and excess water from the bloodstream, but it does not perform the endocrine functions of the kidney.2 When kidneys fail, toxins build up in the body and cause nausea, hypertension, fatigue, and problems with urine output, among other symptoms.3 Once the dialysis process begins, symptoms improve, but the toxin removal can take weeks to months before the patient returns to a relative homeostasis.4 Toxin build up is not the only cause of undesired side effects. Clinicians note that waste removal is contraindicated because there is an accepted loss of valuable blood proteins.5 When a patient loses blood proteins, the risk of sickness and mortality increase.6 Low levels of blood proteins are known to cause detrimental effects, including decreased brain size and cognitive function, altered fat distribution, lethargy, depression, and an overall state of immunosuppression caused by the stress of these low levels of proteins.7 Therefore, the technological challenge in biomaterials is to balance the requirements for toxin removal while preserving blood proteins consisting of antigens, essential molecules, and complexes that are present in the physiological environment.8 Blood proteins are designed to be reactive and will adhere to foreign substances.9 For example, the material used in the current commercial dialysis tubing polyvinylchloride (PVC), is biocompatible in that it is accepted with an appropriate host response.10 PVC is marked by the
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