A Wearable Alternative to Dialysis?

Traditional hemodialysis has many drawback, but a new approach -- using zeolites in a polymer nanofiber mesh -- may make portable blood filtration a reality.

Kidneys are so important to our health that we have two of them! They filter our blood, remove soluble waste products, maintain the electrolyte content and pH balance of the body, and produce a number of important hormones. According to Chinese medicine, kidneys store the congenital energy we receive from our parents, while the K1  kidney meridian point on the sole of the foot is the major entry point for the absorption of energy from the Earth.

Traditional Dialysis

When the kidneys are not functioning property (renal failure), hemodialysis aids in removal of urea and other waste products from the blood. More than 2 million people undergo regular hemodialysis treatments. Dialysis is based on diffusion of liquid components across a semipermeable membrane, driven by the difference in the concentration of the two liquids.

Specific equipment and highly-purified dialysate are needed for the treatment, which can last from two to eight hours and is often repeated every day. Dialysis patients are very vulnerable to electrical outage and natural disasters. In addition, hemodialysis treatments are often not available for patients in developing countries. The clear need to develop a more portable and accessible means to treat kidney failure drove scientists from the National Institute for Materials Science (NIMS) in Tsukuba, Japan, to look for an alternative.

Polymer Nanofiber Filter

The Japanese scientists used an approach of selective filtration of toxic products from blood using zeolites (regular microporous alumosilicate structures). They have tested a variety of zeolites for their ability to specifically absorb creatinine, a breakdown product of creatine phosphate in the muscle, which is normally filtered by the kidneys. Creatinine concentration in the blood is used as a marker of renal health.

Selected zeolites were incorporated into a polymer nanofiber mesh (produced by electrospinning) that was used to filter the blood. The scientists reported their initial findings in Biomaterials Science:

In this study, we develop a zeolite-polymer composite nanofiber mesh to remove uremic toxins for blood purification. The nanofiber is composed of blood compatible poly(ethylene-co-vinyl alcohol) (EVOH) as the primary matrix polymer and zeolites that are capable of selectively adsorbing uremic toxins such as creatinine. The composite fiber meshes were produced by a cost-effective electrospinning method: electrospinning composite solutions of EVOH and zeolites […] The proposed composite fibers have the potential to be utilized as a new approach to removing nitrogenous waste products from the bloodstream without the requirement of specialized equipment.

The nanocomposites, characterized using scanning electron microscopy and X-ray spectroscopy (SEM/EDX), revealed successful incorporation of zeolites from the electrospinning solution into the polymer nanofibers, forming bead-like structures. However, as the zeolite microparticles were enveloped in the nanofibers, their adsorption capacity was lowered, compared to free zeolites, as measured by UV-visible spectroscopy. At its current absorption capacity, the filter would have to be quite bulky (10 cubic centimeters) to absorb a daily portion of creatinine in the body, so further absorption enhancement is needed before it can be used in real life. As the authors have several ideas on how to achieve it, we can hope to see a wearable artificial kidney saving lives in the foreseeable future.

Image by picsfive/123RF.
Source: “What Is Qi? Qi in TCM Acupuncture Theory.” yinyanghouse.com.
Source: “Gross Anatomy and Acupuncture: A Comparative Approach to Reappraise the Meridian System,” by Stefano Marcelli, Medical Acupuncture, February 2013, 25(1): 5-22. doi:10.1089/acu.2012.0875.
Source: NIMS, nims.go.jp.
Source: “Fabrication of Zeolite-Polymer Composite Nanofibers for Removal of Uremic Toxins From Kidney Failure Patients,” K. Namekawa, M.T. Schreiber, T. Aoyagi, & M. Ebara. Biomaterials Science, January 31, 2014. DOI: 10.1039/c3bm60263j.
Source: “Smart Nanofibers as Dialysis Replacement,” worldhealth.net, May 9, 2014.
Source: “Smart Nanofibers to Treat Kidney Failure,” Adarsh Sandhu, medicalxpress.com, March 5, 2014.