for the cells to absorb, or they are insoluble, or they have the potential to cause
tissue damage. On the other hand, nanoparticles are easily taken up by the cell due
to their exceedingly small size. Moreover, they are completely soluble and do not
damage the tissues. Hence, the efficiency of the drug delivery system can be
increased several times by integrating nanoparticles within them. Similarly, the
effectiveness of biopharmaceuticals can be increased several times by coupling
them with nanoparticles, which will proficiently deliver the peptides or proteins at
the tumor site and, in this manner, cure cancer without causing extensive damage
to the adjacent tissues and organs. Owing to their size and properties, nanomaterials
are extensively used for the treatment of a number of diseases. Nanoparticle
contrast agents are being developed for tumor detection purposes. Labeled
nanoparticles and nanolabeled particles are used for MRI. QDs can be used to
measure levels of cancer markers because these are robust and very stable light
emitters. Their photochemical stability and the ability to tune broad wavelengths
make QDs extremely useful for biolabeling [203].
Template synthesis strategies provide excellent control over both the internal
and external dimensions of nanotubes. Because these methods also allow internal
and external surfaces to display disparate functional groups, template-synthesized
nanotubes are very attractive starting points for drug delivery vehicles. Several key
advances have recently been made that bring this goal closer to reality. First,
nanotubes can now be prepared from a much broader range of materials that
includes biocompatible and biodegradable materials such as amino acid polymers,
DNA, alginate, and chitosan. Of those, chitosan is a very promising material for
various kinds of effective applications. In addition, a number of capping strategies
have been developed to retain drug payloads within nanotubes. Finally, nanotubes
have been successfully taken up by target cells, where their payload has been
delivered. In the near future, these advances will be combined for drug-delivery
studies in cell culture and, more importantly, in whole animals.
Drug-delivery strategies using template-synthesized nanotubes [204] can overcome the blood–brain barrier (BBB), which limits the transport of therapeutic
molecules from the blood compartment into the brain, thus greatly reducing the
species of therapeutic compounds that can be efficiently accumulated in the central
nervous system (CNS). Various strategies have been proposed for improving the
delivery of drugs to the brain, and numerous invasive and noninvasive methods
have been proposed by different scientists in an attempt to circumvent the BBB and
to increase the delivery of drug compounds into the brain. An interesting alternative, which solves this problem and also that of reaching a suitable target in the
CNS, has recently been provided through the use of nanoparticulate colloidal
devices as a noninvasive technique for drug delivery to the brain. These systems
offer diverse advantages over invasive strategies, because (a) they are designed
using biocompatible and biodegradable materials; (b) they avoid the disruption and/
or modification of the BBB; and (c) they modulate the biopharmaceutical properties
of the entrapped drugs. Moreover, the possibility of targeting specific brain tissue,
thanks to ligands linked to the surface of the nanoparticulate colloidal devices,
Functionalized Nanoparticles and Chitosan-Based Functional Nanomaterials
37
tissue damage. On the other hand, nanoparticles are easily taken up by the cell due
to their exceedingly small size. Moreover, they are completely soluble and do not
damage the tissues. Hence, the efficiency of the drug delivery system can be
increased several times by integrating nanoparticles within them. Similarly, the
effectiveness of biopharmaceuticals can be increased several times by coupling
them with nanoparticles, which will proficiently deliver the peptides or proteins at
the tumor site and, in this manner, cure cancer without causing extensive damage
to the adjacent tissues and organs. Owing to their size and properties, nanomaterials
are extensively used for the treatment of a number of diseases. Nanoparticle
contrast agents are being developed for tumor detection purposes. Labeled
nanoparticles and nanolabeled particles are used for MRI. QDs can be used to
measure levels of cancer markers because these are robust and very stable light
emitters. Their photochemical stability and the ability to tune broad wavelengths
make QDs extremely useful for biolabeling [203].
Template synthesis strategies provide excellent control over both the internal
and external dimensions of nanotubes. Because these methods also allow internal
and external surfaces to display disparate functional groups, template-synthesized
nanotubes are very attractive starting points for drug delivery vehicles. Several key
advances have recently been made that bring this goal closer to reality. First,
nanotubes can now be prepared from a much broader range of materials that
includes biocompatible and biodegradable materials such as amino acid polymers,
DNA, alginate, and chitosan. Of those, chitosan is a very promising material for
various kinds of effective applications. In addition, a number of capping strategies
have been developed to retain drug payloads within nanotubes. Finally, nanotubes
have been successfully taken up by target cells, where their payload has been
delivered. In the near future, these advances will be combined for drug-delivery
studies in cell culture and, more importantly, in whole animals.
Drug-delivery strategies using template-synthesized nanotubes [204] can overcome the blood–brain barrier (BBB), which limits the transport of therapeutic
molecules from the blood compartment into the brain, thus greatly reducing the
species of therapeutic compounds that can be efficiently accumulated in the central
nervous system (CNS). Various strategies have been proposed for improving the
delivery of drugs to the brain, and numerous invasive and noninvasive methods
have been proposed by different scientists in an attempt to circumvent the BBB and
to increase the delivery of drug compounds into the brain. An interesting alternative, which solves this problem and also that of reaching a suitable target in the
CNS, has recently been provided through the use of nanoparticulate colloidal
devices as a noninvasive technique for drug delivery to the brain. These systems
offer diverse advantages over invasive strategies, because (a) they are designed
using biocompatible and biodegradable materials; (b) they avoid the disruption and/
or modification of the BBB; and (c) they modulate the biopharmaceutical properties
of the entrapped drugs. Moreover, the possibility of targeting specific brain tissue,
thanks to ligands linked to the surface of the nanoparticulate colloidal devices,
Functionalized Nanoparticles and Chitosan-Based Functional Nanomaterials
37