A recent study has documented the successful development of non-woven fabric materials that can absorb uremic toxins. This fabric is based on Nylon 6 containing modified carbon black-graphene nanoplatelets. The study is available as pre-proof in Materials Letters.
Non-Woven Fabric Could Filter Toxins From the Blood Stream
One of the severe health conditions prevailing worldwide is chronic kidney disease (CKD). When CKD patients reach stages III and IV, clinicians remove uremic toxins from the blood via hemodialysis. Typically, a dialyzer is composed of membranes that can separate uremic toxins (waste products) and excess water from the blood.
The membrane material used in hemodialysis requires various properties that include absorption, asymmetry, and homogeneity. Scientists have modified the surface properties of Nylon-6 fibers, one of the most commonly used polymers, such that they can remove uremic toxins from the blood and, therefore, be used in hemodialysis treatment.
Nanomaterials Used to Develop Non-Woven Fabric to Absorb Uremic Toxins
Graphene Nanoplatelets (GNPs) are a class of carbon particle that has been extensively used in membrane technology, especially in the field of membrane separation. Scientists use ultrasounds of different amplitudes and frequencies and diamines (chemical method) to modify GNPs. One of the commonly used adsorbents is carbon black (CB). It is widely used owing to the relatively low cost, high microporosity, and large surface area.
Recently, scientists have developed non-woven fabrics that can absorb uremic toxins and, hence, are useful for treating CKD. As stated above, this fabric is based on Nylon 6 containing GNPs modified with amino groups. Additionally, it also contains CB modified with carboxylic groups by the melt-blowing method. In this process, the fibers are randomly oriented with a prominent homogeneous surface in an orderly, dense fashion. It is important to bind the fibers closely such that it does not collapse.
Characteristic Properties of the Newly Developed Nano-based Fabric
Scientists analyzed the mechanical properties of the newly synthesized material and determined its elongation capacity, tear force, and resistance to breakage. Compared to Nylon 6, which possesses 77% elongation, Nylon-6/GNP/CB exhibited an increased elongation of 98.4%. The enhancement in the elongation might be due to the loading and dispersion of the nanoparticles.
Researchers observed that Nylon-6/GNP/CB exhibited improved tear force and maximum resistance to breakage. Typically, the mechanical behavior of a non-woven fabric depends on the bond strength of the fibers and web density, orientation of the fibers in the fiber web, and fiber slippage.
Characterization of Non-woven Nylon-6/GNP/CB Fabric
Scientists used Scanning Electron Microscopy (SEM) to characterize the newly manufactured fabric. The SEM image of non-woven Nylon 6 fabric revealed smooth and uniform orientation with interconnected pores. The average fiber diameter was measured at 12.5 mm. The Energy-dispersive X-ray spectroscopy (EDS) spectra revealed the presence of three elements, i.e., carbon (C), nitrogen (N), and oxygen (O).
The SEM image of Nylon-6/GNP/CB showed uniform fibers with roughness. Scientists calculated the average fiber diameter to be 17.5 mm. Additionally, this fabric was studied under higher magnification of 7500X, where graphene and carbon black nanoparticles were well dispersed throughout the fiber. Similar to Nylon 6, the EDS spectra of Nylon-6/GNP (0.5%) revealed the presence of C, N, and O elements. However, compared to EDS spectra of Nylon 6, Nylon-6 / GNP revealed increased C and N content and decreased O content. This result hinted at the proper incorporation of C nanoparticles. The porosity of the non-woven Nylon-6/GNP/CB was also found to be marginally increased compared to Nylon 6.
Researchers evaluated the newly developed fabric based on different carbon black and graphene nanoparticle concentrations. They observed that Nylon-6/GNP/CB (0.25 %) could eliminate 90% of urea in three hours and ten minutes after simulating dialysis for four hours. A previous study revealed 79% of urea removal by a polylactic acid (PLA) membrane with immobilized heparin on its surface.
The current study also reported the removal of creatinine and uric acid toxins by Nylon-6/GNP/CB. Researchers reported that 0.5% Nylon-6/GNP/CB non-woven fabric exhibited the highest percentage of removal of creatinine (81%) and uric acid toxins (88%).
The authors of this study stated that the percentage of removal of uric acid using Nylon-6/GNP/CB was greater compared to those reported in previous studies. This result might be owing to the improved porosity and the presence of two adsorbent nanoparticles in the fabric. Importantly, researchers also determined that no adhesion of proteins occurs in the newly developed non-woven fabric.
In this study, scientists revealed that Nylon-6/GNP/CB-based non-woven fabric possesses improved mechanical properties, high porosity, and fibers that are suitably interconnected. As this fabric could significantly remove urea, creatinine, and uric acid, it could be effectively utilized for hemodialysis treatment for patients with CKD.