[Blueboard] Seminar on Nanoparticle Materials

Nina Rosario L. Rojas, Ph.D. nrojas at ateneo.edu
Tue Aug 30 14:26:02 PHT 2005

The Chemistry Department and the National Chemistry Instrumentation Center
invite you to the following lecture in the Department's ongoing seminar



6 Sept. 2005, Tuesday
4:30 p.m.
Schmitt Hall CH 109


Polymeric nanoparticles refer to a covalently cross-linked polymeric
network with a particle size in the nanometer range. Nanoparticles, with
their small size, porous structure, and ability to be appropriately
functionalized, have unique characteristics that can make them powerful
vehicles for carrying drugs and other active molecules. Entrapped inside
these nanoparticles, the integrity and activity of the trapped molecules
are retained and can be released at a controlled rate at target sites.

The presentation will address the following:
a)	synthesis and characterization of poly(acrylic acid), hydrophobically
modified poly(acrylic acid) and starch nanoparticles, and
b)	their applications for drug sequestration and delivery.

Poly(acrylic acid)(PAA) and hydrophobically modified poly(acrylic
acid)(HMPAA) nanoparticles were formed by using the reverse microemulsion
technique. It was observed that these nanoparticles were in the 80-100 nm
range and their surface charge was pH dependent. These particles were
assessed to determine their ability to extract drugs such as
amitriptyline and bupivacaine from bulk fluids for their potential
application as scavengers for overdosed drugs. In normal saline(0.9%
NaCl), unmodified PAA nanoparticles extracted 81% amitriptyline and 62%
bupivacaine in 5 minutes, whereas the HMPAA nanoparticles extracted 68%
and 51% amitriptyline and bupivacaine respectively.

In another study, selective esterification of starch nanoparticles was
performed using Candida antartica Lipase B (CAL-B) in its immobilized
(Novozyme 435) and free (SP-525) forms as catalyst. The starch
nanoparticles were made accessible for acylation reactions by formation
of Aerosol-OT (AOT, bis[2-ethylhexyl]sodium sulfosuccinate) stabilized
microemulsions. Acylation of the starch nanoparticles in microemulsions
at 40„aC for 48 h with vinyl stearate, ƒÕ-caprolactone and maleic
anhydride gave products with degrees of substitution (D.S.) of 0.8, 0.6
and 0.4, respectively. In all cases, substitution occurred
regioselectively at the C-6 position of the glucose repeat units.
Infrared microspectroscopy (IRMS) revealed that AOT coated starch
nanoparticles diffuse into the outer 50 ƒÝm shell of catalyst beads.
After removal of surfactant from the modified starch nanoparticles they
were dispersed in DMSO or water and were shown to retain their

About the Speaker:

Dr. Chakraborty received her Ph.D. from the National Science Foundation
Center for Biocatalysis and Bioprocessing of Macromolecules, Polytechnic
University, New York, NY, where she also was responsible for the
operations and maintenance of the NMR instrumentation laboratory. Aside
from holding various research and teaching positions in India, she
recently completed a post-doctoral fellowship at the Langmuir Center for
Colloids and Interfaces at Columbia University, New York.

Nina Rosario L. Rojas, Ph.D.
Associate Professor
Chair, Department of Chemistry
Ateneo de Manila University
School of Science and Engineering
Loyola Heights, Quezon City
1108 Philippines
Telefax: +63-2-426-1323
Phone: +63-2-426-6001 x5620
nrojas at ateneo.edu

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