Preparation and characterization of biologically nanorods shaped structure pseudo-poly(amino-acid)s containing phthalimide moiety condensed from essential L- amino acids

A class of nanostructured biodegradable poly(ester-imide-sulfonamide)s as pseudo-poly(amino acid)s (PAA)s bearing natural amino acids in the main chain was synthesized. In this investigation, N,N-(Pyromelitoylimidyl)-bis-(4-hydroxy tyrosine dimethyl ester benzyl sulfonamide) (PHTBS) as a biologically diphenol and N,N -(pyromellitoyl)-bis-(L-amino acid) such as L-phenylalanine, L-leucine, S-valine, L-alanine and L-methionine were used for direct polyesterification by tosyl chloride/pyridine/ N,N′-dimethylformamide system as a condensing agent. The novel PHTBS and obtained PAAs were characterized with FTIR, 13C-NMR, 1H-NMR spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy and elemental analysis. Differential scanning calorimetry and thermogravimetric analysis were used to determine the thermal properties of the polymers. X-ray diffractograms of polymers show sharpness peaks with an amorphous background which indicate the crystalline structures in the backbone of polymer. This absorption was confirmed with SEM analysis which show nanorods shaped of obtained polymers. On the basis of thermogravimetric analysis data, such PAAs are thermally stable and can be classified as self-extinguishing polymers. The obtained PAAs possessed more bioactivity, moderate thermal stability and high solubility in common organic solvents. Furthermore soil dehydrogenase activity of the PHTBS and the obtained PAAs assay showed that the synthetic materials are biologically active and then could be classified as bioactive and biodegradable compounds.