Principal
Investigator:
William Riser, PhD,
Professor
Department of Chemistry
Brown
University
Providence,
RI
Brief
Description:
An aerogel is a gel
with a lower density than the fully condensed form of the material that
comprises the gel. Typically,
aerogels are produced by replacing the liquid of a gel with air or another gas
while maintaining the integrity of the gel structure - not allowing complete
collapse. In the field of aerogels,
different gels can be formed with specific properties and functions such as
those widely known as organically modified ceramics. The field of metal aerogels remains
fraught with significant challenges associated with nanoparticle size,
removal/transport of metals in mammalian systems, instability, combustibility in
air and clumping of nanoscale metal particles.
The novel technology
described here improves upon the current metal aerogel fabrication
techniques. Most broadly, the
innovation is a fabrication method, and use, of photo-formed metal
nanoparticles. The inventive method
is a photolytic (x-ray, UV) modification of metal ion-containing aerogels that
creates metal nanoparticles, which can be employed in various analytical,
isolation and chemical transformation processes. As an option, this innovative process
can include the formation of ferromagnetic aerogels that also contain metal
nanoparticles.
Transparent
monolithic aerogels based on silica, the bio-derived polymer chitosan and
coordinated ions serve as a three-dimensional (3-D) scaffold decorated with
metal ions such as Au, Pt and Pd ions.
These metal aerogels, such as Au(III) aerogels can be imaged
photolytically to produce nanoparticles.
This inventive process achieves the goal of obtaining a generally and
selectively absorptive material that is ferromagnetic by combining 1) the
generalized absorption capacity of silica-based polymer-silica hybrid aerogel
with 2) the discovery that gold nanoparticles with specific adsorption
capability can be produced directly by ultraviolet (UV) irradiation of Au
ion-containing aerogels, and 3) the discovery that well-dispersed ferromagnetic
particles can be produced in these aerogels and their particles.
The unique aerogels,
resulting from this method, have several advantages that are amenable to a vast
array of novel applications as detection and optical elements. These inherent benefits include: light transparency in certain wavelength
regions, high porosity and surface areas, reactive metal ions, and absorptive
structure of gases. Many types of
metal ions, gases and organic polymers can be used with this new process. Moreover, the aerogels are friable and
can be used in combination with metal ions and/or reaction products as a
catalytic agent or vehicle.
The aerogel
nanoparticles can be of any size ranging from approximately 100 nm to larger
monolithic structures. For example,
gold nanoparticles can be produced in or on the polymer-silica hybrid aerogel
monoliths by UV irradiation, thus spatially controlled arrays of such particles
can be produced; gold ion-containing aerogel particles can be UV-light
irradiated to produce aerogel particles comprising Au
nanoparticles.
A wide variety of
potential biomedical applications exist for [small] nanoparticles that are
ferromagnetic/superparamagnetic and can selectively interact with biologically
active molecules for separation purposes.
Nanoparticles in colloidal suspensions or spread on surfaces are
available for further chemical reactions in various binding and/detection
applications, e.g., diagnostic assays, protein research and immunoassays,
optical detection. Further
applications involve use as a research tool for basic science in R&D
laboratories – academic, commercial or government. Markets include medical diagnostics and
basic biomedical research and development – for the human and veterinary market
segments, as well R&D in to advance the physical sciences of nanotechnology,
chemical engineering and material sciences.
Information:
US patent 7,767,063 is issued
(8/03/10)
US patent 7,238,261is issued (7/03/2007)
