Nanofabrication Process for Hollow Gold Nanoparticles Unveiled by University of California Santa Clara Researchers

University of California Santa Cruz (UCSC) chemists have created processes for nanometer (nm) hollow shells, spheres and tubes of gold. The Hollow Gold Nanoparticles (HGNs) can be used for detecting chemical and biological analytes and find application in electronics and in microfluidics. 

US Patent Application 20100009338, FIG. 19 shows a high resolution transmission electron micrograph (TEM) of an hollow gold nanoparticle (HGN) formed from a slightly oxidized cobalt particle created by University of California at Santa Cruz Professor of Chemistry Jin Z Zhang,  Adam Schwartzberg and  Tammy Y. Olson.   

The hollow gold nanostructures can be used in microfluidic devices, for detecting chemicals inside or outside a biological membrane, such as a cell membrane or a viral coat, for transporting fluids between devices and structures in analytical devices, for conducting electrical currents between devices and structure in analytical devices, and for conducting electrical currents between biological molecules and electronic devices, such as microchips.

The UCSC inventors provides nanostructures comprised of hollow metal nanospheres or nanoshells and nanotubes for use as chemical sensors, conduits for fluids, and electronic conductors. The nanostructures can be used in microfluidic devices, for detecting chemicals inside or outside a biological membrane, such as a cell membrane or a viral coat, for transporting fluids between devices and structures in analytical devices, for conducting electrical currents between devices and structure in analytical devices, and for conducting electrical currents between biological molecules and electronic devices, such as microchips.

The hollow gold nanoparticles (HGNs) have an interior wall surface diameter and an exterior wall surface diameter thereby defining the wall thickness. The nanofabrication process further provides HGNs having tunable a interior and exterior and wherein the peak of the surface plasmon band absorption is between about 550 nm and about 820 nm. In one embodiment the mean wall thickness of the HGNs is between about 2.4 nm and about 7.3 nm. In a preferred embodiment the mean wall thickness is about 5 nm.

FIG. 6 is a representative low resolution TEM of HGNs. Examining 150 particles from such images, the mean size is found to be 30.+-.4.5 nm.

FIG. 7 is a high resolution TEM of an individual HGN of diameter 29.1 nm with approximately 5 nm wall thickness. Twinning in the HGN wall demonstrates its polycrystalline nature. A TEM of the whole HGNs is inset.

FIG. 20 illustrates TEMs of the gold nanotubes. FIG. 20a is a low resolution TEM image of gold nanotubes. The line indicates the path of a single, about 4 mm tube. FIG. 20b is a high resolution TEM image of a large section of one tube illustrating the continuity and consistency of the samples. FIG. 20c is a high resolution TEM image of one section of the gold tube showing its continuous nature. FIG. 20d is a more detailed high resolution TEM image of the tube showing gold lattice fringes indicating its poly-crystalline nature.

FIG. 1 shows an exemplary synthesis procedure for Hollow Gold Nanoparticles (HGNs).

Fluorescent nanoparticles (quantum dots (QDs) such as semiconductor quantum dots, SQDs) have been used recently as fluorescent biological markers and have been found to be extremely effective. They offer advantages including higher stability, stronger fluorescence, tunability of color, and possibility of optical encoding based on different sized or colored SQDs