Polymer and carbon nanotube bound folic acid and methotrexate for cancer therapy

Abstract

Folic acid (FA) is an amino acid that helps in the replication of normal cells and it deficiency may lead to oncogenic cells development. Methotrexate (MTX) on the other hand is a highly potent drug against leukemia and other neoplasias, which can induce toxic side effects and drug resistance to target cells. The principal objective was to develop a bioconjugate that will enhance therapeutic effectiveness of these agents (FA and MTX) using functionalized carbon nanotubes and polymer toward cancer cells. Furthermore, bioreversible binding to a watersoluble and biocompatible carrier polymer and carbon nanotubes are advanced technology designed to circumvent critical pharmacological and efficacious biological action. The formation of biofissionable bond (CONH) for drug release was evaluated in this work by using nuclear magnetic resonance (NMR) spectra with D2O as solvent, and infrared (IR) spectra to identify the necessary peak shifts for the bioreversible conjugation of FA and MTX as anticancer drug. Polyaspartamide and carbon nanotubes (CNTs) were both functionalized and used as carriers for solubility behavior, steric accessibility and reactivity of anchoring sites, aiming to enhance therapeutic effectiveness of MTX. In order to obtain the polymeric carrier, to polysuccinimide (PSI) synthesized via polycondensation of aspartic acid was attached 3-(N,N–dimethylamino)propylamine (DMP) and 1,3-propylenediamine (PDA) for solubility behavior and reactivity of anchoring of the drug respectively. This, through the use of an ester 2-(1H-benzotrial-1-yl)-1,1,3,3- tetramethylurium hexafluorophosphate (HBTU), as coupling agent led to the polymer drug conjugate after reacting with FA. The reaction was subjected to the polymer cleavage which caused the dropping of yield after chromatography and dialysis operations. After kinetic reaction investigation, the optimum reaction time was set within the range of 120-130 minutes for an optimum yield of coupling within the range of 80-85% where the incorporation of FA in the polymer was maximum though the polymer cleavage. In addition, CNTs obtained via chemical vapour deposition (VCD) was covalently functionalized at RT, 50ºC and 100ºC with a mixture of sulphuric and nitric acids to generate the phenol and carboxyl groups on the surface, and at 230 ºC with aspartic acid to generate only the carboxyl group. It resulted that the mol ratio (OH/COOH) was increasing, the size of f-CNTs was decreasing from 80, 30 to 20nm and the water solubility was increasing with the increase in temperature from RT, 50ºC to 100ºC. The carboxyl on the surface of f-CNTs was attached to DMP and FA through HBTU to get f-CNTs-FA conjugate. This resulted to the prodrug with different sizes of 50nm and 170nm with 94% and 101.3% incorporation of folic acid respectively. CNTs noncovalently coated with polysuccinimide (PSI) in DMF at 160ºC were attached to DMP and PDA. Thereafter, FA reacted with PDA via HBTU to give a prodrug of 60nm with 105.3% FA incorporation. The f-CNTs functionalized with polymer can be more beneficial due to the size for the cell penetration and average molecular weight for renal clearance. Therefore the biomedical evaluation is recommended for future work.