Does Nanotechnology Apply to Dialysis? (2001)

More than 800,000 patients suffering from end-stage renal disease (ESRD) are today treated with renal replacement therapy (RRT), including renal transplantation [1]. The dialytic forms of RRT include hemodialysis and peritoneal dialysis, with the former being used in a large majority of patients in most countries [2]. Extracorporeal hemodialysis has undergone a series of developments in the last three decades mostly related to improvements in biomaterials and enhancement of the design of the critical disposable devices and machines. In particular, while the initial hemodialysis systems were developed piecemeal by dedicated artisans, who were also engineers and physicians, the most recent devices and machines are highly sophisticated and rely on large production series and standardized manufacturing procedures [3, 4]. This evolution has taken place in conjunction with a significant reduction of hemodialyzer dimensions. An important part of this process has been the significantly better understanding of the physiological effects and consequences of dialysis at a micro-scale level, leading to adequate blood circuit design, smooth and biocompatible blood pathways, standardized thickness and porosity of membranes, and accurate alarm systems and failure controls [5–7]. As a result of this enhanced understanding and technical sophistication, we operate today with hemodialyzers with minimal blood priming required, constant and reproducible performance, and minimal dialytic losses of protein compounds, even in the presence of significantly high sieving coefficients for large molecules [8, 9]. One may argue that as we continue to increase dialyzer efficiency, we are getting close to the limits imposed by available or potential membranes and by the commonly utilized mass separation processes. For these reasons, a new interest is growing in hyper-selective barrier separation processes made possible by specifically designed synthetic membranes. Similarly, selective solid separation processes based on the use of newly designed adsorbent materials are under evaluation for newer and more efficient blood purification techniques. The evolution of biomaterials and dialytic techniques has paralleled the evolution of other technologies, including computers and biotechnology [10]. Computers have evolved beyond any expectation, increasing speed, memory, and analytical capabilities, while decreasing in physical size. From the large main frames whose operational time had to be shared among scientists of different institutions, hardware has evolved to highly efficient personal computers, handheld devices, and potent microchips with enormous capacity for data storage and management. Computers have also become key tools in accelerating processes that are occurring in the field of biotechnology, while different biological processes are providing new models for the development of new hardware and software (i.e. DNA-based computers). This process of interaction between biology and electronics/mechanics has been defined ‘bionic convergence’ and may result in a tremendous impact on medicine. In February 1997, researchers created Dolly, a lamb cloned from the DNA of an adult sheep. What was considered impossible in the past, proved feasible, and demonstrated the growing power of new biotechnologies. Further examples could be repre-