Effect of functionalization on drug delivery potential of carbon nanotubes

Figures & data

Scheme 1. Preparation of N-Hydroxy succinimide (NHS) ester of folic acid.

Scheme 2. Conjugation of FA with PEG-bis-amine 3000.

Figure 1. The FTIR spectrum of acid-treated MWCNTs.

Figure 2. The FTIR spectrum of DOX/PEG-FA-MWCNTs conjugate.

Table I. The characteristic peaks interpretation of functionalized MWCNTs.

Functional groups	Frequency (cm^−1)	Observed frequency (cm^−1)
OH-stretching	3400–3600	3447.17
CH-stretching	3000–2850	2925.59
Asymmetric stretching of C = O	1680–1630	1633.58
COOH	3400–2400	3062.11

Table II. The particle size of MWCNTs after purification.

Procured MWCNTs	Particle size	PDI	Zeta potential
	1776.2 nm	0.733	−845.95 mV
MWCNTs heated in hot air oven (250°C)	Sonication time (h)	Particle size (nm)	PDI	Zeta potential (mV)
	1	881.1	0.436	−445.77
	2	363.6	0.174	−846.75
	3	511.4	0.236	−0.36
Microwave treatment (120°C for 15 min)	Sonication time30 min	Particle size (nm)570.9	PDI0.254	Zeta potential (mV)1397.09
	1 h	642.2	0.282	−0.97
Piranha treatment (H2SO4:HNO3::NH4OH:H2O2)	pH	Particle size (nm)		PDI
	6.74	863.4		0.381
Acid treated MWCNTs (H2SO4:HNO3) reflux 8 h	pH	Particle size (nm)		PDI
	7.12	706.1		0.303

Figure 3. Dispersion analysis of MWCNTs in different surfactants (Triton X-100, Tween-80 and sodium lauryl sulfate).

Table III. The dispersion of MWCNTs in different surfactants.

Acid-treated MWCNTs	Amount of water added	Quantity of SLS added	Sonication time (min)	Particle size (nm)	PDI
1 ml	10 ml	20 mg	10	449.1	0.202
1 ml	20 ml	10 mg	15	133.1	0.233

Figure 4. SEM images of DOX/PEG-FA- MWCNTs shown at 50,000 × and 30,000 × magnification.

Figure 5. Motic image of DOX-loaded functionalized MWCNTs.

Figure 6. Cumulative percent drug release from various MWCNTs nanoformulations.

Figure 7. Percent cell viability of MCF-7 cell after treated with free DOX, DOX/MWCNTs, DOX/PEG-MWCNTs and DOX/PEG-FA-MWCNTs.

Figure 8. Cellular uptake of doxorubicin in MCF-7 cell lines.

Table IV. The various pharmacokinetic parameters.

Parameters	Cmax (μg/ml)	AUC(0−t) (μg/ml h)	AUC(0−∞) (μg/ml h)	T1/2 (h)	MRT (h)
Free DOX	6.1	36.23	1.608	1.76	2.34
DOX/ox-MWCNTs	5.92	35.31	1.65	4.6	6.4
DOX/PEG-MWCNTs	6	35.02	0.753	4.7	7.23
DOX/PEG-FA-MWCNTs	6.32	57.87	14.84	13.87	19.43

Figure 9. Biodistribution study of MWCNTs nanoformulations in different organs.