title: Preparation, circular dichroism induced helical conformation and optical property of chitosan acid salt complexes for biomedical applications.
abstract: The efficient procedure for preparation of chitosan acid complexes containing aspartic acid, benzilic acid and terephthalic acid moieties in isopropyl alcohol under mild condition has been demonstrated. The ionic complexation between chitosan and the acid is confirmed by FTIR and 1H NMR spectroscopy. The circular dichroism (CD) spectra of chitosan/aspartic acid complex showed negative (at lambda=312) band, chitosan/benzilic acid and chitosan/terephthalic complexes showed positive (at lambda=286 and 315 nm) band in DMSO, indicating that the polymers adopted helical (left-handed and last two right-handed) secondary structure. The inversion of the CD pattern in chitosan acid salt complexes suggests that there is a change in the chiral structure of the polymer system. Some physical properties and surface morphology were analyzed by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetry (TG) and scanning electron microscopy (SEM). Optical properties of chitosan derivatives are evaluated by photoluminescence (PL) spectroscopy which showed red shift. The introduction of acid moieties into chitosan increases the solubility in most of the organic solvents, which opens new perspectives for the employment of chitosan-based biohybrid in biomedical applications.
authors.affiliation: Department of Chemistry, Motilal Nehru National Institute of Technology, Allahabad 211004, India.
authors.forename: Jay
authors.initials: J
authors.lastname: Singh
authors.forename: P K
authors.initials: PK
authors.lastname: Dutta
mesh_terms: D035843:Biomedical Research; D002152:Calorimetry, Differential Scanning; D002236:Carbohydrate Conformation; D048271:Chitosan / Q000138:chemical synthesis / Q000737:chemistry*; D002942:Circular Dichroism; D009682:Magnetic Resonance Spectroscopy; D008855:Microscopy, Electron, Scanning; D055620:Optical Phenomena; D012492:Salts / Q000737:chemistry*; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013818:Thermogravimetry; D014961:X-Ray Diffraction
chemical_list: D012492:Salts; D048271:Chitosan