Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (10): 2672-2678.doi: 10.3866/PKU.WHXB20101003

• CATALYSIS AND SURFACE STRUCTURE • Previous Articles     Next Articles

Study of Competitive Adsorption Behavior of Protein andMethylene Blue by Optical Waveguide Spectroscopy

DENG Lin, QI Zhi-Mei   

  1. State Key Laboratory of Transducer Technology, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, P. R. China
  • Received:2010-05-24 Revised:2010-07-05 Published:2010-09-27
  • Contact: QI Zhi-Mei
  • Supported by:

    The project was supported by the National Key Basic Research Programof China (973) (2009CB320300), National Natural Science Foundation of China (60978042), and the BaiRenJiHua Programof Chinese Academy of Sciences.


We used time-resolved optical waveguide spectroscopy (OWGS) to in-situ measure visible absorption spectrum for methylene blue (MB) adsorbed ona hydrophilic glass waveguide from an aqueous solution containing proteins such as bovine serum albumin (BSA) and hemoglobin (Hb). The competitive adsorption of MB and the protein was detected at a solution pH lower than the isoelectric point of the protein. Since the competitive adsorption behavior of MB and the protein is very sensitive to the protein concentration, the protein content in the mixed solution was readily determined by time-resolved OWGS. In addition, a kinetic equation for the competitive adsorption of the two molecules was deduced based on the Langmuir adsorption isotherm. The best fit of the measured time course of the absorbance with the theoretical kinetic equation reveals that the number of MB molecules adsorbed on the surface exponentially decreases with time after reaching a maximum.A quasi-linear relationship between the fitting parameters and the protein concentration was also obtained.

Key words: Optical waveguide spectroscopy, Competitive adsorption, Methylene blue, Protein detection


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