In recent years,gelatin has been widely used in medicine,food and industrial due to its protein and biological...
Jun Wang,Bai-Yang Wang,Xin-Jun Mao,Shi-Hua Tang~* College of Chemistry and Ecological Engineering,Guangxi University for Nationalities,Nanning 530006, Guangxi.
Water-soluble gelatin-PbS bionanocomposites （BNCs） were synthesized via a facile one-pot chemical reaction method at pH 7.40. The samples were characterized by transmission electron microscopy （TEM）, X-ray diffraction （XRD）, UV-vis absorption spectra （UV-vis）, Fourier transform infrared spectra （FT-IR） and circular dichroism （CD）. FT-IR data were used to envis- age the binding of PbS particles with oxygen atoms of carbonyl groups of gelatin molecule. The possible integration mechanism between gelatin and PbS was discussed in detail. The effect of Pb2＋ and PbS on the conformations of gelatin has also been analyzed by means of UV-vis, CD and FT-IR spectra, resulting in less c^-helix content and more open structures （[3-sheet, r-turn, or expanded）. A new formula to calculate the association constant was proposed according to the relationship between the absorbance of gelatin-PbS BNCs and the free concentration of PbS, and apparent association constants K （298/303/308 K： 3.11/2.00/1.60 × 10^6 tool/L） at three different temperatures were calculated based on this formula. Thermodynamic parameters such as AG^θ, △Hθ and △S^θ were also determined. The results of the thermodynamic investigations indicated that the reaction was spontaneous （AG^θ 〈 0）, and enthalpy-driven （△H^8 〈 0）.
