Leng Xiaojing, Startchev Konstantin, Buffle Jacques
CABE (Analytical and Biophysical Environmental Chemistry), Department of Inorganic, Analytical and Applied Chemistry, University of Geneva, Science II, 30 Quai Ernest Ansermet, Geneva 4, 1211, Switzerland.
J Colloid Interface Sci. 2002 Jul 1;251(1):64-72. doi: 10.1006/jcis.2002.8429.
The flocculation between the rod-like biopolymer Schizophyllan and two types of colloidal particles (latex with diameter 40 nm and alumina with diameter 60 nm) has been investigated by means of fluorescence correlation spectroscopy (FCS). The concentration ratio of Schizophyllan/particle q was varied in the range 0.1 approximately 20. Under conditions of pH about 5.7, 1 mmol.L(-1) NaCl, and room temperature (22+/-0.5 degrees C), the particles are strongly charged (alumina particles positively charged, latex negatively), while Schizophyllan is neutral. We observed that Schizophyllan chains flocculate with both types of particles, which suggests that the charge neutralization does not play a decisive role in these interactions. The ratio of fluorescence intensity of one floc over that of one particle, Q(f)/Q(p), and the corresponding hydrodynamic radius (r(h)) of the flocs have been measured. For a Schizophyllan-latex system, Q(f)/Q(p) reached a maximum value of 5 for q=3 indicating that the flocs contained five particles on average. The corresponding value of r(h) was r(h)=455 nm. The flocculation kinetic of latex particles with Schizophyllan was too fast to be measurable by FCS. For the Schizophyllan-alumina system, Q(f)/Q(p) was stable at about 1 in the whole studied range of q but r(h) increased with q suggesting that many Schizophyllan chains are adsorbed on individual particles. The flocculation kinetic of this system was studied by FCS and the obtained results were compatible with those of photon correlation spectroscopy.
通过荧光相关光谱法（FCS）研究了棒状生物聚合物裂褶多糖与两种胶体颗粒（直径40 nm的乳胶和直径60 nm的氧化铝）之间的絮凝作用。裂褶多糖/颗粒的浓度比q在0.1至20的范围内变化。在pH约为5.7、1 mmol·L⁻¹ NaCl和室温（22±0.5℃）的条件下，颗粒带强电荷（氧化铝颗粒带正电，乳胶带负电），而裂褶多糖呈中性。我们观察到裂褶多糖链与两种颗粒都发生絮凝，这表明电荷中和在这些相互作用中不起决定性作用。测量了一个絮凝物的荧光强度与一个颗粒的荧光强度之比Q(f)/Q(p)以及絮凝物相应的流体动力学半径（r(h)）。对于裂褶多糖 - 乳胶体系，当q = 3时，Q(f)/Q(p)达到最大值5，表明絮凝物平均包含五个颗粒。r(h)的相应值为r(h)=455 nm。乳胶颗粒与裂褶多糖的絮凝动力学太快，无法通过FCS测量。对于裂褶多糖 - 氧化铝体系，在整个研究的q范围内，Q(f)/Q(p)稳定在约1，但r(h)随q增加，这表明许多裂褶多糖链吸附在单个颗粒上。通过FCS研究了该体系的絮凝动力学，所得结果与光子相关光谱法的结果一致。
