Plastic Antibodies - Designing Receptors for the Next Generation of Biosensors - page 110

Fig. 2 (a) Scanning electron microscopy (SEM) image of a cross-section of the controlled
delivery device containing the MIP nanoparticles-on-microspheres. (b, c) SEM images of the
prepared MIPs microspheres composed of nanoparticles on the surface at 9,000-fold magnification
(b) and 30,000-fold magnification (c). (d) In vitro dissolution profile of omeprazole enantiomers
fromMIP- and NIP-loaded delivery systems in dissolution medium changed every 2 h with pH 1.2,
6.8 and 8.0, respectively (mean SD, n ¼ 6) (adapted with permission from [ 69 ])
exhibited very low cross-reactivity, even for the analogue uracil, which differs from
the template only by a hydrogen atom replacing fluorine. The release of 5-FU from
imprinted MIP nanospheres in simulated plasma fluid showed a sustained release
over 50 h (65% of the total amount of drug loaded), while non-imprinted polymers
completed the release after 5 h (Fig. 2 , right).
Magnetic MIP nanoparticles for drug delivery have been developed by Kan and
coauthors, who grafted an aspirin-imprinted MIP shell onto 12 nm diameter silane-
modified magnetic cores, obtaining 500 nm diameter MIP nanoparticles [ 71 ]. MIP
NPs exhibited good selectivity for the template in comparison with its structural
analogues such as salicylic acid or o -aminobenzoic acid. When tested in vitro,
during the first 2 h magnetic MIPs released about 50% of the loaded drug, while
non-imprinted nanoparticles released about 85%. Due to their magnetic properties,
MIP nanoparticles could be easily separated and manipulated. Theoretically, they
could be used to target the drug release towards particular sites in the body by
exploiting an external magnetic field [ 72 ]. It might be interesting to fabricate
magnetic MIP nanosystems below 100 nm in size suitable for passing through
altered capillary fenestrations in tissues such as sites of inflammation or tumors.