Separation and purification of bio-molecules such as proteins and viruses are important processes in the biotechnology industry. The risk of contamination with either known or unknown viruses in biological or therapeutic products require production processes that - ideally - completely eliminate the risks of virus contamination. Since the existence of very small amounts of viruses with a size of tens of nanometers causes severe damage to the entire bio-process, the filtration of viruses has to be pretty much perfect. Micro- and ultrafiltration have been successfully used in numerous processes as a robust step for virus reduction but they are not 100% effective. Currently used ultrafiltration membranes still allow smaller-sized virus particles to permeate into a small number of abnormally large-sized pores in the membrane. This broad size distribution of pores in ultrafiltration membranes and the low density of pores in track-etched membranes limit the practical use of virus filtration.
Nanopores function as membrane channels in all living systems, where they serve as sensitive electro-mechanical devices that regulate electrical potential, ionic flow, and molecular transport through the cell membrane. Scientists are studying nanopore construction with the goal of making man-made cell membranes and single molecule detectors. So far, nanoporous membrane-based separations simply use the difference in size of the analytes relative to pore size in the membrane. Here, for a nanopore to be useful as a single molecule detector, its diameter must not be much larger than the size of the molecule to be detected. When a single molecule enters a nanopore in an insulating membrane, it causes changes in the nanopore's electrical properties, which then can be detected and measured. In order to bring about selectivity beyond size, it is necessary that methods for functionalizing the membrane pores are available. To that end, researchers have developed a very simple, but versatile, method for decorating the nanoporous membranes with functional groups. By uniformly modifying the internal cavities of nanopores with various polymers they were able to demonstrate selectivities based on size, charge and hydrophobicity of the molecule passing through the nanopore.
Researchers in Singapore functionalized a polymer nanofiber membrane to capture chemical warfare agents such as nerve agents. The nanofibers in the membrane act as a substrate on which the nerve agents get physically adsorbed followed by chemical decomposition.
Silver single crystals were facilely synthesized on a large-scale with good reproducibility in water at room temperature in the presence of carboxyl-functionalized carbon nanotubes, without any additional reducing agent/electrochemical reducing, microwave, sonication or irradiations.