Preparation And Application Of Controlled Functional Gold Nanotube Membranes

The properties of a surface can be intelligently controlled by alternating the states of the modified molecules. These kind of surfaces are also known as"smart surfaces". At the same time, the properties of switchability and reversibility are of benefit for the array membranes. These membranes that change their permeation properties in response to environmental stimuli have been the focus of research in recent years. Potential applications for these stimuli-responsive array membranes include controlled drug delivery, chemical sensors, bioanalysis, microfluid devices, and so on. In the present thesis,the functional polymers were modified on gold films and the surface of gold nanotube membranes, then the characteristic of the films and the membranes were investigated under different conditions, they were expected to be used in preparation of nano-devices and separation of biomolecules, etc.1. The thermosensitive surface was obtained by modifying gold film with carboxyl-poly(N-isopropylacrylamide) (carboxyl-PNIPAm), and then the characteristic of such surface was investigated by SPR sensor and drop shape analyzer. The results showed that there was a clear red shift of 10.3 nm in resonance wavelength and a contact angle change of 8 o from 26 oC to 35 oC. It was suggested that the PNIPAm modified gold film had thermosensitive properties and was expected to be used in biochips for capturing/releasing proteins, cells, etc.2. The thermally switchable gold nanotube membranes were prepared by modifying array membranes with poly(N-isopropylacrylamide) (PNIPAm). Molecular transport of variable pore diameters was investigated by fluorescence measurements using fluorescein sodium and quantum dots as probes. Manipulating the temperature caused large changes in the transport rates. Transport was almost blocked at 25 oC (below the LCST) to the probes, when PNIPAm formed expanded structures. At 40 oC (above the LCST), transport was strongly allowed to the probes, when PNIPAm became compact structures. Furthermore, the thermally switchable gold nanotube membranes are possible to be used in nanofluidic devices, nanogates etc.3. The pH responsive gold nanotube membranes were produced by modifying array membranes with poly(methacrylic acid) (PMAA). PMAA modified gold films were investigated first and the reversible wettability properties were observed: a contact angle change of 18.3 o was detected in the range of pH 5 to pH 7, which base on the change of the chain extension of PMAA according to electrostatic interactions between charged groups which are sensitive to pH of the aqueous solution. Then the PMAA molecules were modified on the array membranes, molecular transport under different pH value was investigated by fluorescence measurements using tris(2'2-bipyridyl) dichlororuthenium(II) hexahydrate (Rubby) and quantum dots as probes. The results showed that transportion properties were changed in the range of pH 5 to pH 7. Such pH responsive gold nanotube membranes were expected to be used in the separation of biomolecules.