Topics in Current Chemistry (2020) 378:15
1 3
Some examples of this approach include the work of Niezabitowska et al. [102]
that employed sodium dodecyl sulfate as anionic surfactant to disperse carbon
nanotubes and polycaprolactone. Negri et al. [103] used SWCNT oxidized with
2% SDBS suspensions to generate nanotubular paramagnetic probes, with potential
utility as contrast agents (CAs) in magnetic resonance imaging (MRI). Cerpa et al.
[104] used a SDBS solution to disperse single-walled carbon nanotubes to obtain
anisotropic relaxation probes for diffusion MRI studies. Bharti et al. [105] compared
the role of a cationic an anionic surfactants in the synthesis and resulting properties of MWCNTs decorated with bi-metallic Pt–Pd nanoparticles. Yasujima [106]
used Triton X-100
®
to disperse CNTs in a bioanode preparation process in a multienzyme immobilized carbon-felt electrode. Martinez-Paz et al. [107] employed
0.015% Pluronic F68 culture medium solution to obtain a homogenous suspension
of oxidized MWCNTs in order to determine the possible toxic effects in invertebrate
Chironomus riparius caused by CNTs environmental dispersion.
2.2.3 Biomolecules
The non-covalent functionalization by attaching biomolecules to the CNTs surfaces
is attracting great attention in biomedical research because of their promising preclinical possibilities. With this aim, different biological molecules and macromolecules can be bound to the nanotubes, like polypeptides, DNA bases, DNA oligonucleotides, amino acids, phospholipids, etc.
2.2.3.1 Proteins Carbon nanotubes can interact directly with proteins through π–π
stacking of their aromatic residues (Trp, Phe, and Tyr) enhancing their absorptivity and biocompatibility [108, 109] and so increasing the possibilities of being used
in preclinical evaluations. A different approach uses a bridge to anchor proteins to
CNTs, either through covalent modifications of nanotubes [110], or by a non-covalent
method employing pyrene derivatives [90].
2.2.3.2 DNA Derivatives DNA can bind to carbon nanotubes, forming helices around
them [111] or can form non-covalent conjugates through the π–π staking with the
aromatic bases [30]. DNA-functionalized CNTs can be used as biological transporters and also as biosensors [111, 112].
2.2.3.3 Phospholipids Due to their amphiphilic nature, phospholipids can be used as
surfactants to solubilize CNTs. Lysophospholipids, or single-chained phospholipids,
are very efficient in this task [113]. In this case, the lipid part wraps the nanotubes
as striations, whereas the hydrophilic part provides CNT solubility and biocompatibility. Using this approach, phospholipid-polyethylene glycol (PEG) is employed to
functionalize SWCNT for a range of different biomedical applications [114] (Fig. 3).
In a different approach, lipid bilayers can encapsulate CNTs, creating a model to
study different biological process occurring at the cell membranes [115].
188
Reprinted from the journal
1 3
Some examples of this approach include the work of Niezabitowska et al. [102]
that employed sodium dodecyl sulfate as anionic surfactant to disperse carbon
nanotubes and polycaprolactone. Negri et al. [103] used SWCNT oxidized with
2% SDBS suspensions to generate nanotubular paramagnetic probes, with potential
utility as contrast agents (CAs) in magnetic resonance imaging (MRI). Cerpa et al.
[104] used a SDBS solution to disperse single-walled carbon nanotubes to obtain
anisotropic relaxation probes for diffusion MRI studies. Bharti et al. [105] compared
the role of a cationic an anionic surfactants in the synthesis and resulting properties of MWCNTs decorated with bi-metallic Pt–Pd nanoparticles. Yasujima [106]
used Triton X-100
®
to disperse CNTs in a bioanode preparation process in a multienzyme immobilized carbon-felt electrode. Martinez-Paz et al. [107] employed
0.015% Pluronic F68 culture medium solution to obtain a homogenous suspension
of oxidized MWCNTs in order to determine the possible toxic effects in invertebrate
Chironomus riparius caused by CNTs environmental dispersion.
2.2.3 Biomolecules
The non-covalent functionalization by attaching biomolecules to the CNTs surfaces
is attracting great attention in biomedical research because of their promising preclinical possibilities. With this aim, different biological molecules and macromolecules can be bound to the nanotubes, like polypeptides, DNA bases, DNA oligonucleotides, amino acids, phospholipids, etc.
2.2.3.1 Proteins Carbon nanotubes can interact directly with proteins through π–π
stacking of their aromatic residues (Trp, Phe, and Tyr) enhancing their absorptivity and biocompatibility [108, 109] and so increasing the possibilities of being used
in preclinical evaluations. A different approach uses a bridge to anchor proteins to
CNTs, either through covalent modifications of nanotubes [110], or by a non-covalent
method employing pyrene derivatives [90].
2.2.3.2 DNA Derivatives DNA can bind to carbon nanotubes, forming helices around
them [111] or can form non-covalent conjugates through the π–π staking with the
aromatic bases [30]. DNA-functionalized CNTs can be used as biological transporters and also as biosensors [111, 112].
2.2.3.3 Phospholipids Due to their amphiphilic nature, phospholipids can be used as
surfactants to solubilize CNTs. Lysophospholipids, or single-chained phospholipids,
are very efficient in this task [113]. In this case, the lipid part wraps the nanotubes
as striations, whereas the hydrophilic part provides CNT solubility and biocompatibility. Using this approach, phospholipid-polyethylene glycol (PEG) is employed to
functionalize SWCNT for a range of different biomedical applications [114] (Fig. 3).
In a different approach, lipid bilayers can encapsulate CNTs, creating a model to
study different biological process occurring at the cell membranes [115].
188
Reprinted from the journal