Biomedical Engineering Reference
In-Depth Information
140
140
120
100
100 nm
100 nm
80
(a)
(b)
10
5
0
(e)
CTAB-1
PSS-1
PDDAC-1
CTAB-4
PSS-4
PDDAC-4
100 nm
100 nm
(c)
(d)
(f)
Figure 27.3
Shape.and.surface.coating.determine.cellular.uptake.of.Au.nanoparticles.in.MCF-7.cells..Transmission.elec-
tron.microscope.images.of.CTAB-coated.Au.nanorods.with.different.aspect.ratios:.(a).CTAB-1,.(b).CTAB-2,.(c).
CTAB-3,. and. (d). CTAB-4.. (e). shape-. and. surface-coating-dependent. cellular. uptake. of. Au. nanorods. coated.
by. CTAB.. (f). Transmission. electron. microscopy. (TEM). images. showing. the. process. of. cellular. uptake.. The.
Au. nanorods. form. aggregates,. enter. into. vesicles. in. this. form,. and. get. into. lysosome.. (Reproduced. with.
Biomaterials
,. 31,. Qiu,. Y.,. Liu,. Y.,. Wang,. L.,. Xu,. L.,. Bai,. R.,. Ji,. Y.,. Wu,. X.,. Zhao,. Y.,. Li,. Y.,. and. Chen,. C.,. Surface.
chemistry.and.aspect.ratio.mediated.cellular.uptake.of.Au.nanorods..7606-7619,.2010..Copyright.2010,.by.per-
mission.from.Elsevier.)
27.2.3 Agglomeration and Aggregation
Nanoparticles. show. greater. biological. activity. than. larger-sized. particles. of. the. same.
chemical.composition,.due.to.their.increased.surface.area.per.mass..The.signiicant.surface.
size. also. allows. for. a. strong. tendency. to. agglomerate/aggregate.. An. agglomeration. is. a.
collection.of.particles.that.are.loosely.bound.together.by.relatively.weak.forces,.including.
van. der. Waals. forces,. electrostatic. forces,. simple. physical. entanglement,. and. surface.
tension,. with. a. resulting. external. surface. area. similar. to. the. sum. of. the. surface. area. of.
the. individual. components.. Aggregation. is. different. from. agglomeration.. Aggregated.
particles.are.a.cohesive.mass.consisting.of.particulate.subunits.tightly.bound.by.covalent.or.
metallic.bonds.due.to.a.surface.reconstruction..This.is.often.accomplished.through.melting.
or. annealing. on. surface. impact,. and. is. typically. a. result. of. having. an. external. surface.
area.signiicantly.smaller.than.the.sum.of.the.individual.components..Agglomerates.may.
be. reversible. under. certain. chemical/biological. conditions. whereas. an. aggregate. will.
