10.2.2.5 Core/Shell Structure Formation
As discussed previously, an extra layer of ‘nano-shell’ can be formed onto radionanomaterials to facilitate further surface engineering, especially when the stability
of initial radionanomaterials is not very ideal. In a very interesting recent study, a
protective gold shell was grown on
124 I-labeled gold nanoparticles and the core/
shell structured nanoplatform was used for in vivo tracking of dendritic cells [9].
Similar strategy was adopted by the same research group in another study for
visualization of macrophage recruitment in an inflammation model [57]. The whole
radiolabeling and shell growth cost less than 30 min.
Compared with covalent conjugation method, the most dominant limitation of
physical interaction-based surface modification methods is that the overall stability
is lower. Also, other physical interaction forces, such as hydrogen bond [58], or
coordination bond [59], can also be readily useful for material surface engineering.
10.3 Examples for Radionanomedicine Surface
Modification
10.3.1 Inorganic Nanomaterials
In this section, we listed several representative categories of inorganic nanomaterials, which include silica nanomaterials, carbon nanomaterials (graphene as
examples), and metal (oxide) nanomaterials [17, 32]. From these examples, we can
have a better understanding about how the methods discussed in Sect. 10.2 can be
properly used in the previous research reports.
10.3.1.1 Silica-Based Nanomaterials
Silica nanomaterials, especially mesoporous silica nanoparticles (MSNs), were
considered as important drug delivery vectors owing to their ultrahigh surface area
and good biocompatibility [60]. As stated previously, the most frequently adopted
method for surface modification is the usage of silane coupling agents [8]. The
pristine silica nanomaterials usually have abundant silanol groups on the surface,
which can cause the irregular agglomeration of silica nanomaterials via the
hydrogen bonding [36]. These agents usually have bifunctional structures with one
end attached to the silica nanomaterials (via reaction with silanol groups) while the
other end can provide reaction sites for biomolecule conjugation.
In an early study, MSNs were functionalized with 3-aminopropyltriethoxysilane
(APTES) for incorporation of amine groups on the surface, after which
DOTA-NHS was reacted with surface NH 2 for subsequent
64 Cu labeling [61]. As
expected, the MSNs still tend to aggregate in vivo (judging by potent accumulation
192
D. Chen and H. Hong
As discussed previously, an extra layer of ‘nano-shell’ can be formed onto radionanomaterials to facilitate further surface engineering, especially when the stability
of initial radionanomaterials is not very ideal. In a very interesting recent study, a
protective gold shell was grown on
124 I-labeled gold nanoparticles and the core/
shell structured nanoplatform was used for in vivo tracking of dendritic cells [9].
Similar strategy was adopted by the same research group in another study for
visualization of macrophage recruitment in an inflammation model [57]. The whole
radiolabeling and shell growth cost less than 30 min.
Compared with covalent conjugation method, the most dominant limitation of
physical interaction-based surface modification methods is that the overall stability
is lower. Also, other physical interaction forces, such as hydrogen bond [58], or
coordination bond [59], can also be readily useful for material surface engineering.
10.3 Examples for Radionanomedicine Surface
Modification
10.3.1 Inorganic Nanomaterials
In this section, we listed several representative categories of inorganic nanomaterials, which include silica nanomaterials, carbon nanomaterials (graphene as
examples), and metal (oxide) nanomaterials [17, 32]. From these examples, we can
have a better understanding about how the methods discussed in Sect. 10.2 can be
properly used in the previous research reports.
10.3.1.1 Silica-Based Nanomaterials
Silica nanomaterials, especially mesoporous silica nanoparticles (MSNs), were
considered as important drug delivery vectors owing to their ultrahigh surface area
and good biocompatibility [60]. As stated previously, the most frequently adopted
method for surface modification is the usage of silane coupling agents [8]. The
pristine silica nanomaterials usually have abundant silanol groups on the surface,
which can cause the irregular agglomeration of silica nanomaterials via the
hydrogen bonding [36]. These agents usually have bifunctional structures with one
end attached to the silica nanomaterials (via reaction with silanol groups) while the
other end can provide reaction sites for biomolecule conjugation.
In an early study, MSNs were functionalized with 3-aminopropyltriethoxysilane
(APTES) for incorporation of amine groups on the surface, after which
DOTA-NHS was reacted with surface NH 2 for subsequent
64 Cu labeling [61]. As
expected, the MSNs still tend to aggregate in vivo (judging by potent accumulation
192
D. Chen and H. Hong