Preparation and evaluation of aqueous phase compatible molecularly imprinted polymers for shikimic acid
Shikimic acid (SA) is an important component in the production of several important drugs particularly the anti-influenza drug, Oseltamivir. Naturally, SA exists as an intermediate in the plant biosynthesis of aromatic compounds via shikimate pathway. Commercially, SA is extracted from the Chi...
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Format: | Thesis |
Language: | English |
Published: |
2015
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Subjects: | |
Online Access: | http://psasir.upm.edu.my/id/eprint/71198/1/FS%202015%2089%20IR.pdf |
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Summary: | Shikimic acid (SA) is an important component in the production of several important
drugs particularly the anti-influenza drug, Oseltamivir. Naturally, SA exists as an
intermediate in the plant biosynthesis of aromatic compounds via shikimate pathway.
Commercially, SA is extracted from the Chinese star anise or produced through the
fermentation process by modified strain of Escherichia coli (E. coli). Regardless of the
method of production, SA needs to be purified before it can be used for the intended
purpose. Conventional method in the purification of SA usually involved the use of
non-specific adsorbents that are less effective in isolating the SA. Molecularly
imprinted polymer (MIP) being one of the latest adsorbents in separation science,
offers an alternative technique that is more selective and specific than the conventional
adsorption methods.
MIP is known to be not compatible to the aqueous phase with usually low or no
selectivity, making the preparation of MIP that work well in aqueous phase a challenge
to those in the field. Reported in this thesis are exploratory work carried out to prepare
non-covalent imprinted polymer for SA with the aim that the polymer prepared is
capable of working in highly aqueous environment in which the raw extract of SA is
usually in.
“Trial and error” approach was used as the preliminary tool in searching the right
formulation of template:monomer:cross-linker (TMX) ratio that produced a good
imprinted polymer judging from the imprinting factor (IF) scores of the polymer in
batch rebinding experiments. The optimized TMX ratio finally determined was 1:6:10 in 10 mL methanol and water (4:1, v/v) porogen system. The best template: monomer
(TM) ratio was also evaluated using ultraviolet (UV) spectroscopy approach, the
results obtained were in agreement with the preliminary “trial and error” results,
indicated that TM ratio of 1:6 was the optimal.
The polymer was physically characterized using Fourier transform infrared (FTIR)
spectroscopy and scanning electron microscopy (SEM) techniques. Results indicated
that complete polymerization was achieved and different morphologies observed
between imprinted and control polymers may be used to explain the imprinting effect
shown by the SA imprinted polymer. Optimization on the rebinding conditions
suggested that the SA imprinted polymer performed best in 100% aqueous
environment at pH 4.0.
Binding isotherm study suggested that the binding sites distribution was heterogeneous
in nature and it can be well described using Freundlich isotherm model. Study of the
polymer’s adsorption kinetic concluded that the adsorption process obeyed pseudo
second order kinetic with rate constant, K of 0.0047 gmg-1min and the experimental
maximum adsorption for SA imprinted polymer was determined as 38.8 mgg-1.
Cross-reactivity experiments results showed that the imprinted polymer having good
selectivity toward SA and the polymer was packed into cartridge and used for the
separation of SA from artificial mixture of SA, methyl shikimate (SE) and gallic acid
(GA) in tap water. A clean separation with three isolated peaks as shown in high
performance liquid chromatography (HPLC) chromatogram was obtained. |
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