Functionalized Multi Walled Carbon Nanotubes as a Carrier for Doxorubicin: Drug Adsorption Study and Statistical Optimization of Drug Loading by Factorial Design Methodology

Farahani, Bahman Vasheghani; Behbahani, Gholamreza Rezaei; Javadi, Nasrin

doi:10.5935/0103-5053.20150318

Bahman Vasheghani Farahani ^**e-mail: bvasheghanif@gmail.com

Department of Chemistry, Faculty of Science, Imam Khomeini International University, 288, Qazvin, Iran

Gholamreza Rezaei Behbahani

Department of Chemistry, Faculty of Science, Imam Khomeini International University, 288, Qazvin, Iran

Nasrin Javadi

Department of Chemistry, Faculty of Science, Imam Khomeini International University, 288, Qazvin, Iran

*e-mail: bvasheghanif@gmail.com

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Figure 1
Synthesis of MWNTs-PEG.

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Figure 2
SEM images of (a) MWNTs-COOH; (b) MWNTs-PEG.

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Figure 3
FTIR spectra of (a) MWNTs; (b) MWNTs-COOH; (c) MWNTs-PEG.

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Figure 4
TGA of (a) MWNTs; (b) MWNTs-COOH; (c) MWNTs-PEG; (d) PEG.

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Figure 5
Raman spectra of (a) MWNTs; (b) MWNTs-PEG; (c) MWNTs-PEG-DOX.

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Figure 6
Main effects plot of parameters for DOX adsorption; effect of (a) pH; (b) adsorbent dosage; (c) DOX concentration and (d) time.

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Figure 7
Correlation between the experimental and predicted values.

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Figure 8
Adsorption kinetics of DOX on MWNTs-PEG: (a) pseudo-first order; (b) pseudo-second order; (c) Elovich and (d) intra-particle diffusion models.

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Figure 9
Effect of temperature on DOX adsorption (C₀ = 10, 20, 50, 70 and 80 mg L^-1, m_(MWNTs-PEG) = 0.8 g L^-1, pH 7, time = 35 min).

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Figure 10
Plots of ln(q_e/C_e) vs. q_e for DOX adsorbed on MWNTs-PEG.

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Figure 11
Release of DOX from MWNTs-PEG at pH 5.5 and 7.4.

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Table 1
Experimental ranges and levels of the factors used in the factorial design

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Table 2
Experimental design and percentage of drug loading

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Table 3
Estimated regression coefficients of significant factors (coded units) and their effects for DOX entrapment

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Table 4
Observed and predicted values of DOX adsorption efficiency

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Table 5
Kinetics parameters for DOX adsorption on MWNTs-PEG by various kinetic models

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Table 6
Isotherm parameters for the adsorption of DOX on MWNTs-PEG

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Table 7
Thermodynamic parameters for DOX adsorption on MWNTs-PEG

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Independent variable	Coded symbol	Range	Level
Independent variable	Coded symbol	Range	–1	1
Solution pH	pH	3-11	3	11
Adsorbent dosage / (g L^-1)	A	0.2-1	0.2	1
Drug concentration / (mg L^-1)	D	10-70	70	10
time / min	T	3-35	3	35

Run	pH	A	D	T	Entrapment / %
1	−1	−1	−1	−1	1.21
2	1	−1	−1	−1	81.2
3	−1	1	−1	−1	2.89
4	1	1	−1	−1	88.9
5	−1	−1	1	−1	1.49
6	1	−1	1	−1	83.7
7	−1	1	1	−1	4.93
8	1	1	1	−1	92.3
9	−1	−1	−1	1	4.41
10	1	−1	−1	1	84.7
11	−1	1	−1	1	11.9
12	1	1	−1	1	88.9
13	−1	−1	1	1	3.92
14	1	−1	1	1	80.6
15	1	1	1	1	81.7
16	−1	1	1	1	8.21

Term	Effect	Coefficient	t-Value	P-Value	DF	SS	MS	F-Value	Error / %
Constant (x)		44.2	61.8	0	1	−	−	−	−
pH	74.3	40.02	55.2	0	1	5231.8	5231.8	2982.1	29.8
A	4.12	2.12	3.08	0.006	1	148.2	148.2	9.16	0.41
D	4.02	2.07	3.05	0.007	1	132.7	132.7	8.3	5.23
T	4.22	2.22	3.09	0.005	1	151.3	151.3	9.42	0.58
pHA	−0.42	−0.16	−0.27	0.601	1	1.9	1.9	0.12	3.52
pHD	2.89	1.81	2.12	0.014	1	113.7	113.7	6.1	0.21
pHT	−0.21	−0.11	−0.13	0.749	1	0.3	0.3	0.02	11.99
AD	−0.19	−0.99	−0.09	0.689	1	0.1	0.1	0.01	1.12
AT	0.12	0.072	0.11	0.902	1	1.2	1.2	0.1	10.89
DT	−0.39	−0.17	−0.29	0.653	1	2.3	2.3	0.14	0.13
pHAD	−0.42	−0.23	−0.34	0.695	1	8.2	8.2	0.42	3.99
pHAT	−1.01	−0.52	−0.76	0.398	1	4.1	4.1	0.18	0.82
pHDT	−0.67	−0.33	−0.53	0.491	1	2.02	2.02	0.12	18.88
ADT	−0.49	−0.21	−0.31	0.623	1	5.3	5.3	0.23	1.02
pHADT	−0.78	−0.42	−0.57	0.426	1	6.4	6.4	0.33	2.32

Run	pH	A	D	T	Drug loading / %		Residual
Run	pH	A	D	T	Theoretical	Experimental	Residual
1	–1	–1	–1	–1	1.23	1.42	0.32
2	1	–1	–1	–1	70.02	78.2	−0.31
3	–1	1	–1	–1	4.82	4.02	−0.29
4	1	1	–1	–1	89.3	80.05	−0.58
5	–1	–1	1	–1	1.65	1.28	0.06
6	1	–1	1	–1	75.62	88.21	0.21
7	–1	1	1	–1	5.42	4.23	−0.62
8	1	1	1	–1	94.3	93.92	1.25
9	–1	–1	–1	1	2.88	4.82	−0.53
10	1	–1	–1	1	78.32	76.98	0.12
11	–1	1	–1	1	11	7.26	0.42
12	1	1	–1	1	89.3	88.5	0.79
13	–1	–1	1	1	3.98	4.58	−0.92
14	1	–1	1	1	94.8	95.01	1.02
15	1	1	1	1	95.23	96	1.31
16	–1	1	1	1	6.8	7.23	−2.33

Kinetic model	Parameter	Value	Kinetic model	Parameter	Value
Pseudo-first order	q_e	12.026	Elovich	α	103.42
	K₁	0.345		β	0.596
	R²	0.994		R²	0.992
	RSS	0.749		RSS	1.009
Pseudo-second order	q_e	13.133	intra-particle diffusion	C_i	6.867
	K₂	0.043		K_i	0.467
	R²	0.999		R²	0.979
	RSS	0.037		RSS	2.796

Temperature / K	Langmuir isotherm model			Freundlich isotherm model
Temperature / K	q_max	K_L	R²	K_F	n	R²
288	53.402	1.032	0.9326	24.924	4.843	0.9904
298	41.597	0.823	0.9275	22.888	4.531	0.9931
310	28.98086	0.595	0.9333	20.7055	4.333	0.9898

Thermodynamic parameter	K₀ / (kJ moL^-1)	ΔG⁰ / (kJ moL^-1)	ΔH0 / (kJ moL^-1)	ΔS0 / (J moL^-1)
293	603.23	–15.60	–44.6	–101
298	411.25	–14.91
310	217.22	–13.87

[1] *e-mail: bvasheghanif@gmail.com

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Functionalized Multi Walled Carbon Nanotubes as a Carrier for Doxorubicin: Drug Adsorption Study and Statistical Optimization of Drug Loading by Factorial Design Methodology