Chemistry Reference
In-Depth Information
Fig. 10
Top
: Schematic illustration of the reversible GS-II- and GlcNAc-DNA-mediated assem-
bly of AuNP-DNA. Lectin-DNA-AuNP networks are dissociated by external stimuli:
temperature-induced DNA melting or competition with free GlcNAc. After competition with
free GlcNAc, the particles are separated by centrifugation enabling reassembly by the new
addition of GS-II. Note that the scheme is not drawn to scale. ssDNA refers to single-stranded
DNA.
Bottom
: GS-II-mediated assembly of AuNP-DNA-GlcNAc and subsequent competition
with GlcNAc or
D
-lactose. Photographs of the samples: AuNP-DNA-GlcNAc, AuNP-DNA-
GlcNAc 2 days after the addition of GS-II, AuNP-DNA-GlcNAc 2 days after addition of GS-II,
and subsequent addition of GlcNAc or
D
-lactose (from left to right). Figure reprinted with kind
permission from ref. [
60
]
single-stranded DNA (DNA-GlcNAc) to form DNA-GlcNAc-functionalized AuNPs
(AuNP-DNA-GlcNAc) is demonstrated. The particles assemble in the presence of
the tetrameric lectin GS-II with four CRDs with affinity for GlcNAc [
62
]. Assemblies
built up by the GS-II AuNP-DNA-glyco interaction were shown to be equipped with
two reversible binding modes that enable the reversible dissociation by two indepen-
dent external stimuli: temperature-induced DNA duplex melting and displacement of
the DNA-glyco ligands from the CRDs of the lectin by competition with free
sugar [
60
](Fig.
10
).
3.3
Interaction with Cells
3.3.1 Cyto- and Genotoxicity
Numerous reports about toxicity and nontoxicity of metal nanoparticles can
be found in literature [
29
,
63
-
80
]. Most of the reports are dominated by
results concerning AuNPs. Silver, known for its antibacterial function for
more than 100 years, also plays an important role. However, gold absolutely
dominates the scene. Silver (15-25 nm), gold (5-6 nm), and silver-gold alloy
nanoparticles (10-12 nm), protected either by poly(vinylpyrrolidone) (PVP) or
