1. Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China 2. Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Abstract：The conformational transition of poly γ-glutamic acid (γ-PGA) embedded with magnetite nanoparticles under various pH conditions was investigated by Fourier transform infrared spectroscopy (FTIR). The secondary structure content was determined through the analysis of amide Ⅰ bands of Fourier deconvolution spectra, secondary derivative spectra and the Gaussian curve fitting of the original infrared spectra. The results showed that the conformation of the γ-PGA was affected by solution pH. The total contents of β-sheet and β-turn were higher than 65％, while α-helix and random coil were low. The content of β-turn increased with increasing pH, while the β-sheet decreased. Additionally, the zeta potential results showed that the pH-sensitive secondary structure of γ-PGA had influence on the stability of suspension of magnetic γ-PGA nanospheres. The minimum value of zeta potential (-35.4 mV) was obtained at pH 10.2.
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