For example, the researchers show how the technology can be used to develop effective, low-cost water purification devices that could be used in developing countries.
“Atomic layer deposition is a technique that can be used to create thin films for coating metals or ceramics, and is especially useful for coating complex nanoscale structures,” says Dr. Roger Narayan, the paper’s lead author. “This paper shows how atomic layer deposition can be used to create biologically functional materials, such as materials that have antibacterial properties. Another example would be a material that does not bond to proteins in the body, which could be used for implantable medical sensors.” Narayan is a professor in the joint biomedical engineering department of NC State’s College of Engineering and the University of North Carolina at Chapel Hill.
One of the applications discussed in the paper is a material that could be used as a filter for point-of-use water purification. “This would be very helpful in the developing world, or in disaster situations – like Haiti – where people do not have access to safe water,” Narayan says. “Over one billion people do not have access to safe water. This can lead to a variety of public health problems, including cholera and hepatitis.”
Specifically, the researchers show that atomic layer deposition can be used to create a film for coating nanoporous membranes, which may be used for filtering out pathogenic bacteria. “The film could also provide antimicrobial functionality,” Narayan says, “to neutralize bacteria.”
In the study, the researchers found that membranes treated with one of these films were able to neutralize two common pathogens: E. coli and Staphylococcus aureus. The researchers are currently working with colleagues to assess how well the membranes perform against a variety of environmental bacteria. It’s anticipated that these membranes could find use in a variety of medical and environmental health applications, such as hemodialysis filters and implantable sensors.
The research, “Atomic layer deposition-based functionalization of materials for medical and environmental health applications,” is published in the March issue of the journal Philosophical Transactions of the Royal Society A. The research was funded by the National Science Foundation and the National Institutes of Health. The research was co-authored by Narayan, Dr. Nancy Monteiro-Riviere, professor of investigative dermatology and toxicology at the Center for Chemical Toxicology Research and Pharmacokinetics at NC State, Dr. Chunming Jin, a post-doctoral research associate at NC State, and Dr. Junping Zhang, a former post-doctoral research associate at NC State. Additional co-authors were from Kodak Research Laboratories, Argonne National Laboratory, North Dakota State University, National Yang-Ming University in Taiwan, and Taipei Medical University in Taiwan.
Note to editors: The study abstract follows.
“Atomic layer deposition-based functionalization of materials for medical and environmental health applications”
Authors: Roger J. Narayan, Nancy A. Monteiro-Riviere, Chunming Jin and Junping Zhang, North Carolina State University, et al.
Published: March 2010, Philosophical Transactions of the Royal Society A
Abstract: Nanoporous alumina membranes exhibit high pore densities, well-controlled pore sizes, uniform pore sizes and straight pores. Owing to these unusual properties, nanoporous alumina membranes are currently being considered for use in implantable sensor membranes and water purification membranes. Atomic layer deposition is a thin-film growth process that may be used to modify the pore size in a nanoporous alumina membrane while retaining a narrow pore distribution. In addition, films deposited by means of atomic layer deposition may impart improved biological functionality to nanoporous alumina membranes. In this study, zinc oxide coatings and platinum coatings were deposited on nanoporous alumina membranes by means of atomic layer deposition. PEGylated nanoporous alumina membranes were prepared by self-assembly of 1-mercaptoundec-11-yl hexa(ethylene glycol) on platinum-coated nanoporous alumina membranes. The pores of the PEGylated nanoporous alumina membranes remained free of fouling after exposure to human platelet-rich plasma; protein adsorption, fibrin networks and platelet aggregation were not observed on the coated membrane surface. Zinc oxide-coated nanoporous alumina membranes demonstrated activity against Escherichia coli and Staphylococcus aureus bacteria. The results of this work indicate that nanoporous alumina membranes may be modified using atomic layer deposition for use in a variety of medical and environmental health applications.