SYNTHESIS AND PROPERTIES
Uniform Particles of Pure and Silica Coated Cholesterol
Dr. Egon Matijevic'
(the Victor K. LaMer Professor of Colloid and Surface Science
at Clarkson University) uses precipitation to prepare uniform
crystalline colloidal cholesterol particles of narrow size distribution.
This method consists of adding a miscible non-solvent (water)
to cholesterol solutions of different alcohols and acetone, without
any additives. The properties of the resulting particles depend
in a sensitive way on the concentration of all reactants, temperature,
pH, ionic strength, and aging time. See Figures 1 and 2. The major
observed effects are due to the solubility of cholesterol, which
is strongly affected by the solvent mixture and temperature.
represents one of the essential biochemical compounds in the animal
kingdom, because it is involved in numerous body-functioning tasks
that range from the synthesis of bile acids and steroid hormones
in vivo to maintaining a proper transport balance within
cellular membranes. However, due to the lack of ability to make
cholesterol soluble from different sources by micellar, vesicular
and bilayer cleansing agents in bile, as well as lipoprotein complexes
in blood, this steroid may deposit on the vessel walls. This causes
problematic health issues that include gallstone formation, intestinal
lumen deposits, and artheriosclerotic plaque.
1. SEM of cholesterol particles prepared with 1-propanol
as solvent using a standard precipitation procedure (SPP), sampled
after10 minutes of reaction time.
SEM of cholesterol particles prepared using reactant concentrations
as in the SPP, but with different temperature and aging conditions.
These particles precipitated at 31 degrees C and aged at 37 degrees
C for 5 hours.
to be able to control the deposition and dissolution of cholesterol,
investigations of its crystallization in simple environments may
be useful in providing information critical for medicine and chemotherapeutics.
Also, uniform colloidal cholesterol particles of various morphologies
could serve as excellent model systems for the evaluation of different
factors on the properties and reactivity of this steroid. Professor
Matijevic's work demonstrates that such dispersions can be obtained
by using his method. Precipitation in a 1-propanol/water system
yields stable dispersions of well-defined particles, which are
used to evaluate the effects of different experimental parameters
on their properties. Aging of stable dispersions results in multilayered
aggregation of the primary platelets, the degree and rate of which
are strongly affected by temperature and ionic strength (salt
content in the environment). In addition, Professor Matijevic'
has shown that colloidal cholesterol particles can be coated with
homogeneous silica layers in order to alter their surface characteristics.
Professor Dan Goia's Research
in Fine Metallic Particles Generates High Interest and Attracts
Significant External Support
Dan Goia is involved in the synthesis, characterization, and modification
of ultra-fine and nanosize metallic and metal-composite particles
with controlled size, shape, internal structure, composition,
and surface properties. Besides already being used extensively
in catalysis, electronics, metallurgy, and pigments, these materials
are starting to impact many emerging technological fields such
as medicine, biology, defense, nonlinear optics, energy generation,
and magnetic storage. Professor Goia's research in this field
over the past five years has resulted in 12 US, European, and
worldwide patents and has attracted significant interest from
both government agencies and industrial sponsors.
Distinguished Lectureship presented
R.O. Lawton Distinguished Professor Michael Kasha (of Florida
Solar 11-Year Cycle of Giant Proton Storms and their Geophysical
September 17, 2007
Science Center , Room 360 Clarkson University
Art, Science and Music of String Instruments” September
18, 2007, Science Center , Room 360, Clarkson University
CAMP Fall Meeting
Potsdam , New York
October 15 - 17, 2007
Egon Matijevic' Day
October 18, 2007
Potsdam , New York.
CAMP’s Annual Technical Meeting Canandaigua
, New York
May 14– 16, 2008
CAMP’s Thirteenth International Symposium on Chemical-Mechanical
Hilton Resort Lake Placid , New York August 10 - 13, 2007
information about CAMP industrial short courses, please
call Professor Richard Partch at 315-268-2351 or send email
to him at firstname.lastname@example.org).
Information, on these and other CAMP events, is
available at the CAMP website