Biomedical Engineering Reference
In-Depth Information
Nanoparticle synthesis
Bottom up methods
(build up from smaller entities)
Top down methods
(size reduction)
Physicochemical
solvent/nonsolvent
Explosion
processes
Precipitation
Vapor
deposition
Aerosol
processes
Mechanical
milling
Condensation
Sol/gel synthesis
Ablation
Chemical
etching
Sputtering
Metal salts
Metal nanoparticles
Figure 2.2
Various approaches for making nanoparticles.
platinum nanoparticles exhibit morphology (size and shape) dependent
catalytic properties [26]. Other agents such as poly(N-vinyl-2-pyrrolidone)
have been used in conjunction with NaBH4 reduction of H
2
PtCl
6
6H
2
O
[27, 28]. h e size of Pt nanoparticles can be produced using chemical rip-
ening [29]. h e initial step of this multistep, multi-seed process starts with
small individual platinum seeds in a water solution containing sodium
citrate and L-ascorbic acid. h e i nal diameter of the nanoparticles relies
on the concentration of chloroplatinic acid and the initial seed size [29].
2.3 Gold Nanoparticles
Gold has fascinated scientists for ages and is now heavily utilized in chem-
istry, biology, engineering, and medicine [30-32]. h ese materials can be
synthesized reproducibly, modii ed with apparently limitless chemical func-
tional groups, and, in certain cases, characterized with atomic-level preci-
sion. Many examples of highly sensitive and selective assays based upon gold
nanoconjugates have been described in the literature. Recently, the focus has
