Synthesis of Poly(L-lactide)-poly(ε-caprolactone)-poly(ethylene glycol) Terpolymer Grafted onto Partially Oxidized Carbon Nanotube Nanocomposites for Drug Delivery.

Nanocomposites prepared with a terpolymer of poly(L-lactide) (PLLA)-poly(ε-caprolactone) (PCL)-poly(ethylene glycol) (PEG) and partially oxidized carbon nanotubes (CNTs) were synthesized and characterized to evaluate their ability to act as an effective nanocarrier of the anticancer drug methotrexate. The homopolymers of PLLA and PCL were synthesized through ring-opening polymerization (ROP) and characterized through gel permeation chromatography (GPC). The PLLA-PCL-PEG terpolymers were synthesized through a four-step chemical route using oxalyl chloride as a linker agent and analyzed with H-NMR, C-NMR, and FTIR spectroscopies. Additionally, the nanocomposites were characterized through FTIR, and X-ray photoelectron spectroscopy (XPS), as well as the differential scanning calorimetry (DSC) technique. XPS analysis revealed that PLLA-PCL-PEG terpolymer chains are grafted onto CNTs. Moreover, evaluations through FTIR and DSC strongly suggest that the PCL-rich domains are preferentially oriented toward CNTs. The release tests exhibited a "burst effect" profile, which was more evident in the terpolymers than in the nanocomposites. Five models were used to assess methotrexate's in vitro release. For the nanocomposites, the best fit to the experimental data was obtained using the first-order model, whereas the results obtained from the Korsmeyer-Peppas model indicated that Fickian diffusion drives methotrexate's release.