Functionalized
CNT

Modification
approach

Biocompatibility/
Solubility

Reference

 

 

 

 

Glucosamine-MWCNT

Oxidative covalent

Good biocompatibility

[169]

 

 

 

 

CS-MWCNT
(CS: chitosan)

Oxidativecovalent

Reduced aggregation, high dispersibility and long term stability in 2% acetic acid.

[170]

 

 

 

 

CS-MWCNT-Cu2+

Covalent

Improved electrical conductivity and stability

[19]

 

 

 

 

CS-MWCNT

Wet-grinding assisted ultrasonication

Improved wettability and homogeneous dispersion

[171]

 

 

 

 

Galactose-MWCNT

Oxidative  covalent

Improved dispersibility in aqueous solvents.

[172]

 

 

 

 

PVP-MWCNT

Polymerization and blending

Remarkable solubility in water, ethanol and dimethylformamide (DMF)

[173]

 

 

 

 

 

 

 

 

PPy-MWCNT
(PPy: Poly propylene)

Oxidativecovalent

Improved solubility and conductivity

[174]

 

 

 

 

α-Pyrene-MWCNT

Reversible addition –fragmentation chain transfer polymerization

Increased solubility with the surface coverage of the polymer.

[175]

 

 

 

 

Pyrene-MWCNT

Covalent

Improved solubility

[176]

 

 

 

 

MWCNT-COOH

Acid oxidation

Decreased length, increased solubility and colloidal stability in polar solvents like water and ethanol

[177]

 

 

 

 

MWCNT-Amine
(Amine: dicyandiamide and
phenylbiguamide)

Oxidative covalent

Uniform dispersion, good interfacial binding, better compatibility

[178]

 

 

 

 

SWCNT-OH
(hydroxyl nanotubes)

Fluorine displacement

Stable suspension in water, ethanol and dimethyl formamide. Improved compatibility with biomolecules

[88]

 

 

 

 

SWCNT-tetrafluoric acetic
 group

Covalent

Improved dispersion in water, ethanol and DMF

[179]

 

 

 

 

SWCNT-2-propanol-2-yl

Covalent attachment under UV-light

Bundle dissociation, improved solubility in organic solvent, retained electronic structure

[180]

Cellulose-SWCNT

Covalent

Easily dispersed and stable for 7 days at the content of 10 mg/ml

[181]

 

 

 

 

CNT-SDS
(SDS: sodium dodecylsufate;
Anionic surfactant)

Non-covalent 

Decreased aggregation,
Dispersion in both aqueous and organic solvents

[182, 183]

CNT-NaDDBS
(NaDDBS: Sodium dodecylbenzene
sulfonate)

 

 

 

Triton-100

 

 

 

 

 

 

 

SWCNT-pyrene-Protein

Non-covalent

Increased dispersion

[184]

SWCNT-PEG-FITC

Non-covalent
(π - π stacking of aromatic FITC)

Solubilized CNTs

 

MWCNT-PEI-DNA

Non-covalent

Improved dispersion

[166]

 

 

 

 

Table 2: Functionalization strategies for improved solubility and biocompatibility of CNTs.