Biomedical Engineering Reference
In-Depth Information
supported-membrane structure to achieve low noise and high-speed
performance is suggested on the basis of the observed relation between
the single-ion-channel current noise and the pore size [40].
6.4 Dendrimers
Dendrimers are highly branched macromolecules with controlled near
monodisperse three-dimensional structure. Polymer growth starts from a
central core molecule and growth occurs in an outward direction by a
series of polymerization reactions. Hence, precise control over size can be
achieved by the extent of polymerization, starting from a few nanometers.
Cavities in the core structure and folding of the branches create cages and
channels. h e surface groups of dendrimers are amenable to modii cation
and can be tailored for specii c applications. h erapeutic and diagnostic
agents are usually attached to surface groups on dendrimers by chemical
modii cation [41]. Drug delivery is an interdisciplinary i eld of research
used by pharmaceutical researchers, medical doctors and industries. Safe
and targeted drug delivery could improve the performance of some classic
medicines already on the market, and moreover, will have implications for
the development and success of new therapeutic strategies such as antican-
cer drug delivery, peptide and protein delivery and gene therapy.
Nanoparticles (NPs) have been developed as an important strategy to
deliver conventional drugs, recombinant proteins, vaccines and more
recently, nucleotides. Nanoparticles modify the kinetics, body distribution
and drug release of nanoparticulate drugs using polymeric NPs, ceramic
NPs, magnetic NPs, polymeric micelles and dendrimers, as well as their
applications in therapeutics, diagnostics and imaging. h e bow-and-arrow
approach is very important, where the drugs are the arrows and the deliv-
ery vehicles are the bows. Polymers, dendrimers, micelles, vesicles, and
nanoparticles have been used as delivery vehicles. Mechanically inter-
locked molecules (MIMs) can be designed in such a way so that they either
change shape or shed of some of their parts in response to a specii c stimu-
lus, such as changes in redox potential, alterations in pH, irradiation with
light, or the application of an oscillating magnetic i eld, allowing a ther-
anostic payload to be released from the nanopores to a precise location at
the appropiate time.
Chlamydia trachomatis
is a bacterial pathogen respon-
sible for genital infections, as well as inl ammatory arthritis. Chlamydia is
treated with antibiotics such as azithromycin (AZ). Neutral generation-4
polyamidoamine (PAMAM) dendrimers are used as intracellular drug-
delivery vehicles into chlamydial inclusions, conjugated with Azithromycin
