158
Y. Min et al.
assemblies, the inter-particle distance (0.8–2.5) that depends on the length of the
oligo(phenyleneethynyl) rod is generally shorter than the linker length (1.4–2.7),
which may indicate a tangential arrangement of the rigid rod structure at the Au
NP’s surface. Dithiol coupling was reported as an efficient method to covalently
link Au NP and Au nanorods (length = 50 nm, width 5 nm) [96]. In this work, the
control of the position, spacing, and quantity of Au NP per nanorod is achieved
through anisotropic surface functionalization of the nanorod with aminoalkylthiols
of increasing size. The dithiol coupling was performed by converting the terminal
amines on polyethylene glycol-stabilized Au NP into thiols through an excess
of a cyclic thioimidate (Traut’s reagent, 2-iminothiolane HCl). Au NP (4.3 nm)
functionalized with norbornenethiol were cross-linked by ring-opening metathesis
polymerization (ROMP) with the use of a water-soluble pyridine-substituted ruthenium benzylidene catalyst [95]. The ROMP of the Au NP can be achieved across a
large area, stitching the NP crystalline domains together.
The amination reaction of fullerene C 60 with amine-functionalized Au NP [121]
was used to produce C 60 -linked Au NP [122]. For the assembly, the C 60 were reacted
with 4-aminothiophenoxide/hexanethiolate-protected Au NP. Although resulting
from a non-covalent bond, the affinity of streptavidin for biotin results in the
strongest biological interaction known, and it was used for the end-to-end linkages of gold nanorods [123]. A protonolytic cross-linking reaction of aluminumorganic-stabilized Pt NP with bifunctional alcohols (ethylene glycol, hydroquinone,
4,4
-dihydroxybiphenyl, and 1,10-decanediol) was reported by Bönnemann et al. to
build 3-D Pt NP networks [99]. The key feature of this synthesis is the formation of
an organometallic colloidal protecting shell around the Pt NP. When reacting with
bifunctional ligands, a cross-linking of the NP occurs that leads to the formation
of a 3-D NP network (Fig. 5.22). The control of the inter-particle distance can be
achieved by varying the length of the spacer molecules (Table 5.3). Finally, cadmium
selenide NP (2.7 nm) modified with 2-aminoethanethiol were cross-linked with the
homobifunctional amine-reactive cross-linker glutaraldehyde [97].
5.2.2.3 Biomolecular Coupling
Compared to linking using small organic ligands, linking with biomolecules
including DNA, supramolecular protein [124], and viruses offers several advantages.
First, these biomolecules can be tailored to specific lengths by varying the number
of base pairs. Additionally, the double-helix structure of DNA is rigid, enabling the
precise control of the spacing. Thus, NP network engineering with DNA gives independent control of three important design parameters (NP size, lattice parameters,
and crystallographic symmetry) by separating the identity of the particle from the
variables that control its assembly [125]. One-, two-, and three-dimensional assemblies of metal NP have been obtained with DNA. There is a very rich literature on that
subject, and we will discuss in this section some basic principles of NP assembly with
DNA. The readers particularly interested in this subject, which has already found
some applications in (electro)catalysis (sometimes the DNA can be removed through
Y. Min et al.
assemblies, the inter-particle distance (0.8–2.5) that depends on the length of the
oligo(phenyleneethynyl) rod is generally shorter than the linker length (1.4–2.7),
which may indicate a tangential arrangement of the rigid rod structure at the Au
NP’s surface. Dithiol coupling was reported as an efficient method to covalently
link Au NP and Au nanorods (length = 50 nm, width 5 nm) [96]. In this work, the
control of the position, spacing, and quantity of Au NP per nanorod is achieved
through anisotropic surface functionalization of the nanorod with aminoalkylthiols
of increasing size. The dithiol coupling was performed by converting the terminal
amines on polyethylene glycol-stabilized Au NP into thiols through an excess
of a cyclic thioimidate (Traut’s reagent, 2-iminothiolane HCl). Au NP (4.3 nm)
functionalized with norbornenethiol were cross-linked by ring-opening metathesis
polymerization (ROMP) with the use of a water-soluble pyridine-substituted ruthenium benzylidene catalyst [95]. The ROMP of the Au NP can be achieved across a
large area, stitching the NP crystalline domains together.
The amination reaction of fullerene C 60 with amine-functionalized Au NP [121]
was used to produce C 60 -linked Au NP [122]. For the assembly, the C 60 were reacted
with 4-aminothiophenoxide/hexanethiolate-protected Au NP. Although resulting
from a non-covalent bond, the affinity of streptavidin for biotin results in the
strongest biological interaction known, and it was used for the end-to-end linkages of gold nanorods [123]. A protonolytic cross-linking reaction of aluminumorganic-stabilized Pt NP with bifunctional alcohols (ethylene glycol, hydroquinone,
4,4
-dihydroxybiphenyl, and 1,10-decanediol) was reported by Bönnemann et al. to
build 3-D Pt NP networks [99]. The key feature of this synthesis is the formation of
an organometallic colloidal protecting shell around the Pt NP. When reacting with
bifunctional ligands, a cross-linking of the NP occurs that leads to the formation
of a 3-D NP network (Fig. 5.22). The control of the inter-particle distance can be
achieved by varying the length of the spacer molecules (Table 5.3). Finally, cadmium
selenide NP (2.7 nm) modified with 2-aminoethanethiol were cross-linked with the
homobifunctional amine-reactive cross-linker glutaraldehyde [97].
5.2.2.3 Biomolecular Coupling
Compared to linking using small organic ligands, linking with biomolecules
including DNA, supramolecular protein [124], and viruses offers several advantages.
First, these biomolecules can be tailored to specific lengths by varying the number
of base pairs. Additionally, the double-helix structure of DNA is rigid, enabling the
precise control of the spacing. Thus, NP network engineering with DNA gives independent control of three important design parameters (NP size, lattice parameters,
and crystallographic symmetry) by separating the identity of the particle from the
variables that control its assembly [125]. One-, two-, and three-dimensional assemblies of metal NP have been obtained with DNA. There is a very rich literature on that
subject, and we will discuss in this section some basic principles of NP assembly with
DNA. The readers particularly interested in this subject, which has already found
some applications in (electro)catalysis (sometimes the DNA can be removed through