## 3 Results and Discussion
A similar observation was found in Figure 4b, which shows Raman spectra of f-CNTs, pure SMZ, and SMZ-CNTs with various degree of functionalization. Crystal structures of GF-CNT\({}_{\rm x}\) and SMZ-CNT\({}_{\rm x}\) were also studied using XRD, and Figure 5 shows the diffractogram of GF-CNT\({}_{\rm x}\) and SMZ-CNT\({}_{\rm x}\). It can be seen that the crystal structure remained unchanged with the incorporation of the f-CNTs. The diffractograms of pure drugs and drug-CNTs were identical. This implies that there were no changes in polymorphism. The melting points of drug-CNT composites were analyzed by DSC 6000. The results are presented in Table 2. It can be seen that there was no significant change in melting points between the pure drug and its f-CNT composites. \begin{table}
\begin{tabular}{c c c c c c} \hline  & **Incorporation \%** & **C:COOH** & **T\({}_{\text{50}}\) (min)** & **T\({}_{\text{80}}\) (min)** & **M\({}_{\text{P}}\) (\({}^{\circ}\)C)** \\ \hline \multirow{4}{*}{GF-CNT\({}_{\text{x}}\)} & 0 & 39.5 & 8.0 & \textgreater{}120.0 & 221.25 \\  & 3.9 & 23.2 & 6.0 & 60.0 & 220.75 \\  & 4.2 & 19.8 & 4.5 & 44.0 & 220.92 \\  & 3.8 & 16 & 4.0 & 30.5 & 221.01 \\ \hline \multirow{4}{*}{SMZ-CNT\({}_{\text{x}}\)} & 0 & 39.5 & 23.5 & 52.5 & 170.37 \\  & 2.9 & 23.2 & 8.5 & 16.5 & 170.21 \\ \cline{1-1}  & 1.3 & 19.8 & 7.5 & 15.0 & 170.06 \\ \cline{1-1}  & 1.4 & 16 & 6.0 & 11.5 & 170.05 \\ \hline \end{tabular}
\end{table} 
Table 2: Dissolution and melting point of sulfamethoxazole-CNTs (SMZ-CNTs) and grisefoulvin-CNTs (GF-CNTs). Figure 5: (a) X-Ray diffractometer (XRD) diffractogram of (A) f-CNT\({}_{23,2}\), (B) pure GF, (C) GF-CNT\({}_{23,2}\), (D) GF-CNT\({}_{19,8}\), and (E) GF-CNT\({}_{16}\); (b) XRD diffractogram of (A) f-CNT\({}_{23,2}\), (B) pure SMZ, (C) SMZ-CNT\({}_{23,2}\), (D) SMZ-CNT\({}_{19,8}\), and (E) SMZ-CNT\({}_{16}\). Dissolution measurements were carried out based on the standard US Pharmacopeia Method (USP 41). GF-CNT composites were added to 4 mg/ml sodium dodecyl sulfate while SMZ-CNT composites were added to 0.1 N hydrochloric acid. The samples were stirred with a paddle at 75 rpm and heated to maintain a temperature of 37 \(\circ\)C. A small amount of medium was withdrawn at different times, filtered with a PTFE membrane to remove f-CNTs, and analyzed with Agilent 8453 UV-visible Spectroscopy System (Agilent, Santa Clara, CA, USA) to determine the amount of drug dissolved, at 291 nm for GF and 265 nm for SMZ. The dissolution data is presented in Figure 6.  
Figure 6: (**a**) Dissolution of GF-CNTs, (**b**) dissolution of SMZ-CNTs, and (**c**) time to reach 80% dissolution for drugs (80) with a degree of functionalization of CNTs. It is evident from both profiles that the increase in the level of functionalization in the f-CNTs enhanced the release of the drugs. The f-CNTs were hydrophilic and increased contact between the water and the drug crystals. The water molecules adsorbed on the hydrophilic carboxylic groups and then used these as a conduit to the drug crystal to increase dissolution. The time necessary to reach 50% (t\({}_{50}\)) and 80% (t\({}_{80}\)) dissolution reduced with the incorporation of the f-CNTs. For GF samples, t\({}_{50}\) and t\({}_{80}\) reduced by as much as 50% and 75%, while for the SMZ samples, t\({}_{50}\) and t\({}_{80}\) were reduced by as much as 74% and 78%. As the C:COOH ratio decreased from 23.2 to 16, the t\({}_{50}\) of GF dropped from 6.0 to 4.0 min, a reduction of 33%, and the t\({}_{80}\) of GF dropped from 60.0 to 30.5 min, a reduction of 49%. The corresponding drop for SMZ was from 8.5 to 6.0 min, a reduction of 31% for t\({}_{50}\) and from 16.5 to 11 min, a reduction of 33% for t\({}_{80}\).