Biomedical Engineering Reference
In-Depth Information
imaging. modalities. such. as. magnetic. resonance. imaging.. This. obstacle. was. obliterated,.
however,. when. nanotechnology. approaches. offered. means. to. deliver. tens. of. thousands.
of.copies.of.the.imaging.agent.for.every.single.molecular.binding.site,.thereby.raising.the.
local.concentration.well.above.the.detection.threshold.for.imaging.
In.the.recent.decade,.there.has.been.an.explosion.of.nanotechnology.research.and.devel-
opment. toward. site-targeted. imaging. contrast. agents,. therapeutics,. and. combinations.
thereof.. This. chapter. is. not. a. thorough. review. of. this. very. broad. ield. of. research,. but.
rather.a.discourse.on.the.overall.clinical.goal.for.this.area.of.nanomedicine.focusing.on.
examples.from.one.lab.to.illustrate.that.story..For.a.more.extensive.scrutiny.of.the.subject,.
the.reader.is.directed.to.many.helpful.publications.freely.available.via.the.Internet.
4-16
4.2 NanoparticleApproachtoTargetedImaging
Whether.speciically.based.upon.fullerenes,.nanocages,.nanotubes,.nanocrystals,.nanocol-
loids,.dendrimers,.liposomes,.viruses,.copolymers,.or.many.other.nano-sized.constructs,.
the.general.nanoparticle.approach.to.theragnostics.(Figure 4.1).is.to.have.a.central.core.or.
backbone.into.or.onto.which.other.components.can.be.placed.for.targeting,.imaging,.drug.
delivery,.and.pharmacodynamic.control.
4.2.1 Targeting
Passive. targeting. can. be. inluenced. through. size,. charge,. and. surface. coating. of. nano-
particles.
17
. Accumulation. of. the. nanoparticles. occurs. based. on. natural. responses. of.
the. body. to. the. foreign. objects,. be. that. differential. permeability,. phagocytosis,. or. other.
Payloads:
Metal chelates (Gd
3+
)
Fluorophores,
Radionuclides,
Genes/Drugs
Carrier:
Nanoparticles (perfluorocarbon emulsions)
Liposomes, Polymers, Microbubbles
19
F
Targeting system:
Monoclonal Antibody
Aptamers, Peptidomimetics,
Polysaccharides, etc.
FIGURE 4.1
Generalized. paradigm. for. nanoparticles. as. imaging. and. therapeutic. agents.. Regardless. of. the. technique.
employed,.the.common.theme.is.to.have.a.core.(whether.solid,.liquid,.hollow,.or.polymeric.scaffolding).into.or.
onto.which.“payloads”.(such.as.drugs.and.imaging.agents).are.incorporated.and.delivered.to.a.speciic.site.in.
the.body.by.targeting.ligands.(such.as.antibodies,.etc.).attached.to.the.outer.surface..The.speciic.nanoparticle.
emulsion. discussed. herein. is. a. liquid. perluorocarbon. core. encapsulated. by. a. phospholipid. monolayer. that.
holds.drug.(e.g.
,
.fumagillin).and.targeting.peptidomimetics.(e.g.,.to.α
ν
β
3
.integrin)..(Reprinted.with.permission.
from.Lanza,.G.M.,.et.al.,.
Medica Mundi
,.47,.34-39,.2003.)
