ABSTRACT
There is increasing interest in using nanopores in synthetic membranes as resistive-pulse sensors for biomedical analytes. Analytes detected with prototype artificial-nanopore biosensors include drugs, DNA, proteins, and viruses. This field is, however, currently in its infancy. A key question that must be addressed in order for such sensors to progress from an interesting laboratory experiment to practical devices is: Can the artificial-nanopore sensing element be reproducibly prepared? We have been evaluating sensors that employ a conically shaped nanopore prepared by the track-etch method as the sensor element. We describe here a new two-step pore-etching procedure that allows for good reproducibility in nanopore fabrication. In addition, we describe a simple mathematical model that allows us to predict the characteristics of the pore produced given the experimental parameters of the two-step etch. This method and model constitute important steps toward developing practical, real-world, artificial-nanopore biosensors.
Subject(s)
Crystallization/methods , Electrochemistry/instrumentation , Electrophoresis, Gel, Pulsed-Field/instrumentation , Membranes, Artificial , Nanostructures/chemistry , Nanotechnology/instrumentation , Ultrafiltration/instrumentation , Electrochemistry/methods , Electrophoresis, Gel, Pulsed-Field/methods , Equipment Design , Equipment Failure Analysis , Macromolecular Substances/chemistry , Materials Testing , Microfluidic Analytical Techniques/instrumentation , Microfluidic Analytical Techniques/methods , Molecular Conformation , Nanostructures/ultrastructure , Nanotechnology/methods , Particle Size , Porosity , Quality Control , Sensitivity and Specificity , Surface Properties , Ultrafiltration/methodsABSTRACT
Nanotube-containing membranes prepared by the template method show promise for use as highly selective filters for membrane-based chemical and biological separations. Most of the work to date has been done on gold nanotubes prepared by electroless deposition of Au within the pores of polymeric filtration membranes. These polymeric filters have very low porosities (< 1%), and, as a result, the flux through Au nanotube membranes based on these templates is very low. In contrast, the other popular template membranes-anodic aluminas-have high porosities-30% to 50%. In spite of this potential advantage of anodic alumina templates, there have been no reports of electrolessly plated Au nanotubes within the pores of these templates. This is because the electroless plating method used to deposit Au nanotubes in polymeric templates does not work in aluminas. We have developed a modified electroless plating strategy that can be used to deposit high-quality Au nanotubes within the pores of the alumina templates. We describe this new plating method here.
