Biomedical Engineering Reference
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factors of NAM and its analogues were evaluated, and good correlations were found
between the interaction energies and the retention factors. When the porogens had
poor hydrogen-bonding capacity, the interaction energy was mainly influenced by
the dielectric constant of the solvent, and when the porogen had strong capacity in
forming hydrogen bond, both the dielectric constant of the solvent and the
hydrogen-bonding interference affected the formation of the template-monomer
complex and the corresponding interaction energy.
A computational optimization of the monomer formulation of molecularly
imprinted catalysts (MIC) for lipase-catalyzed transesterification process was
demonstrated [ 71 ]. The authors screened the intermediates of the lipase-catalyzed
transesterification process commonly containing “catalytic triad” motif made up of
compounds such as serine, histidine, and aspartic acid [ 172 - 174 ]. To construct the
virtual intermediates, p -nitrophenyl acetate was used as substrate and monomers
containing carboxylate moieties as molecular recognition elements. The energy of
each intermediate was then minimized using the semiempirical MOPAC method
with a minimum RMS gradient of 0.100, which specifies the convergence criteria
for the gradient of the potential energy surface. AM1 theory was used with a closed
shell function to calculate heat of formation (
H f) of the intermediates, which
represents the gas-phase heat of formation at 298 K of 1 mol of the intermediate
from its elements in their standard state. The result of this work has been utilized
successfully for the design of artificial lipases.
QM are perhaps the most accurate approaches currently used in the field of
molecular modeling, because the modeling method involves fewer “assumptions”
and the results depend entirely on the accuracy of performed calculations. How-
ever, the sheer size of the required computations currently does not allow realistic
modeling of supramolecular systems.
D
2.7 Rational Approaches to MIP Design Involving Quantum
Chemical Methods
QC methods have been widely employed, mainly for the reason that the computa-
tional cost is kept to a minimum. Further, several studies have shown that they also
lead to accurate estimations. This is because QC methods employ calculations of
electronic structures of molecules leading to more reliable results of non-covalent
interactions, more specifically of pre-polymerization mixtures (Table 1 ).
2.8 Examples of Quantum Chemical Methods Used in MIP
Design
QC approaches have been successfully used to perform optimization studies
through selection of appropriate functional monomers. This was shown by the
design of MIPs that recognized theophylline [ 67 ], N , O -dibenzylcarbamate [ 175 ],
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