Organic functionalization of single-walled carbon nanotubes (SWCNTs) with some chemotherapeutic agents as a potential method for drug delivery

Figures & data

Figure 1 Covalent grafting of various drugs to the SWCNT.

Figure 2 Scanning electron microscopy (SE M) images of SWCNT (without functional groups).

Figure 3 Solubility of grafted SWCNT–betahistine A) in dimethylformamide (DMF) and dimethylsulfoxide (DMSO) and B) in H₂O.

Figure 4 Infrared spectra of A) SWCNT-COOH, B) pure betahistine, and C) grafted SWCNT–betahistine.

Table 1 Covalent grafting of various drugs to SWCNT

Entry	Drug scaffold (a)	Drug name (properties)	Product (b)
1	Amantadine	Antiviral and antiparkinson
2	Metformin	Antidiabetic
3	Gabapentin	Antiepileptic
4	Betahistine	Antivertigo
5	Dipyridamol	Antiplatelet
6	Lisinopril	Antihypertensive
7	Atorvastatin	Blood cholesterol lowering

Table 2 Infrared absorption bands obtained from the acid-treated SWCNTs and drugs grafted to SWCNTs’ solid samples

Compound	Region (cm^−1)	Band assignments
SWCNT-COOH	1,737	Carboxylic acid C=O stretching vibration of SWCNTs
	3,407	Carboxylic acid OH stretching vibration of SWCNTs
1b	1,630	Amide C=O stretching vibration
2b	1,660	Amide C=O stretching vibration
3b	1,630	Amide C=O stretching vibration
4b	1,663	Amide C=O stretching vibration
5b	1,626	Ester C=O stretching vibration
6b	1,656	Amide C=O stretching vibration
7b	1,713	Ester C=O stretching vibration

Figure 5 Ultraviolet-visible absorption spectra of A) betahistine in dimethylformamide (DMF), B) pure SWCNTs and, C) grafted SWCNT–betahistine (functionalized SWCNTs).

Figure 6 Transmission electron microscopy (TEM) images of A) grafted SWCNT– betahistine, B) grafted SWCNT–dipyridamol, and C) grafted SWCNT–lisinopril (Table 1, entries 4b–6b). The arrows indicate the grafted drugs to SWCNT.

Figure 7 Time course for the cumulative release of A) betahistine and B) dipyridamol from grafted SWCNT–betahistine and SWCNT–dipyridamol, respectively, in phosphate-buffered saline (PBS).