title: Chitosan-modified carbon nanotubes-based platform for low-density lipoprotein detection.
abstract: We have fabricated an immunosensor based on carbon nanotubes and chitosan (CNT-CH) composite for detection of low density lipoprotein (LDL) molecules via electrochemical impedance technique. The CNT-CH composite deposited on indium tin oxide (ITO)-coated glass electrode has been used to covalently interact with anti-apolipoprotein B (antibody: AAB) via a co-entrapment method. The biofunctionalization of AAB on carboxylated CNT-CH surface has been confirmed by Fourier transform infrared spectroscopic and electron microscopic studies. The covalent functionalization of antibody on transducer surface reveals higher stability and reproducibility of the fabricated immunosensor. Electrochemical properties of the AAB/CNT-CH/ITO electrode have been investigated using cyclic voltammetric and impedimetric techniques. The impedimetric response of the AAB/CNT-CH/ITO immunoelectrode shows a high sensitivity of 0.953 Ω/(mg/dL)/cm(2) in a detection range of 0-120 mg/dL and low detection limit of 12.5 mg/dL with a regression coefficient of 0.996. The observed low value of association constant (0.34 M(-1)s(-1)) indicates high affinity of AAB/CNT-CH/ITO immunoelectrode towards LDL molecules. This fabricated immunosensor allows quantitative estimation of LDL concentration with distinguishable variation in the impedance signal.
authors.affiliation: Department of Science and Technology Centre on Biomolecular Electronics, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi, 110012, India.
authors.forename: Md Azahar
authors.initials: MA
authors.lastname: Ali
authors.forename: Nawab
authors.initials: N
authors.lastname: Singh
authors.forename: Saurabh
authors.initials: S
authors.lastname: Srivastava
authors.forename: Ved V
authors.initials: VV
authors.lastname: Agrawal
authors.forename: Renu
authors.initials: R
authors.lastname: John
authors.forename: M
authors.initials: M
authors.lastname: Onoda
authors.forename: Bansi D
authors.initials: BD
authors.lastname: Malhotra
mesh_terms: D015374:Biosensing Techniques; D048271:Chitosan / Q000737:chemistry*; D004563:Electrochemistry; D006801:Humans; D057230:Limit of Detection; D008077:Lipoproteins, LDL / Q000302:isolation & purification*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D017971:Tin Compounds / Q000737:chemistry
chemical_list: D008077:Lipoproteins, LDL; D037742:Nanotubes, Carbon; D017971:Tin Compounds; C109984:indium tin oxide; D048271:Chitosan