Biology Reference
In-Depth Information
Figure 2.18
(a)Dimericcapsuleof(
)
with tetraethylammonium cation as a guest characterized
by mass spectrometry (electron spray ionisation).
4
). (b) Tetrahedral capsule of (
4
2.6
Applications
Supramolecular nanotubes and nanospheres can be considered to
be mimics of helical and icosahedral viruses, respectively. As such,
they can be used for the same purposes, carrying a load or guest and
releasing it at a desired location. Such vectors can be used to address
drug-targetingproblemslikecellspecificityandpharmacokinetic
issues.Drugsgenerallyarenotdeliveredspecificallytotheirsite
ofactionresultinginuntowardsystemicefects,essentiallydueto
the need to use doses higher than those strictly required to observe
thedesiredpharmacodynamicefect.Moleculesmaybedegraded
metabolically or their lipophilicy may be inadequate for proper
delivery.Forexample,toopolarentitiesmaysimplybeexcreted
renally while too lipohilic molecules may be metabolized by the liver
orstoredinfatcompartments.Sideefectsmayalsoresultsfrom
lackofsitespecificity,othertissuesororgansbutthedesiredones
being also reached by the drug.
All these problems can be solved or greatly alleviated by using
adequate packaging systems for drugs. The tobacco mosaic virus
(TMV,2tmv,2om3)[90,91]remainsvirulentoverdecadesalthoughits
RNAcontentcouldbeeasilycleavedbyribonucleases.Nevertheless,
the ribonucleic genetic information is so well protected inside the
helicalproteincapsidthatsuchafatefuleventcannothappen(Fig.
Search WWH ::
Custom Search