Chitosan-Modified Carbon Nanotubes-Based Platform for Low-Density Lipoprotein Detection
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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)/cm2 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–1s–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.
KeywordsLow density lipoprotein Impedance spectroscopy Carbon nanotubes Chitosan Nanocomposite
The authors thank Director NPL, New Delhi, India, for the facilities. Md. Azahar Ali is thankful to CSIR, India for the award of Senior Research Fellowship. V. V. A. is thankful to TSDP-DST and CSIR empower project for funding. The financial support received from Department of Science and Technology, India (grant no. DST/TSG/ME/2008/18) and Indian Council of Medical Research, India (grant no. ICMR/5/3/8/91/GM/2010-RHN) is gratefully acknowledged.
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