Moringa oleifera Seed Protein Adsorption to Silica: Effects of Water Hardness, Fractionation, and Fatty Acid Extraction.
Moringa oleifera Seed Protein Adsorption to Silica: Effects of Water Hardness, Fractionation, and Fatty Acid Extraction.
复制标题
辣木种子蛋白对二氧化硅的吸附：水硬度、分馏和脂肪酸提取的影响。
作者：
Brittany A Nordmark;Toni M. Bechtel;J. K. Riley;D. Velegol;Stephanie B Velegol;T. Przybycien;R. Tilton
受发展中国家提议使用阳离子蛋白改性砂进行水过滤的启发，这项研究涉及辣木种子蛋白对二氧化硅表面的吸附。这些蛋白质在不同硬度的模型水中制备，并经历不同程度的分级，包括脂肪酸提取和阳离子交换层析。通过椭圆光度法测量吸附等温线，并通过转盘流动电位法测量所得蛋白质修饰表面的zeta电位。结果表明，脂肪酸的存在对油橄榄阳离子蛋白吸附等温线影响不大。在低浓度下，未分级提取物的吸附与阳离子分离蛋白的吸附没有区别，但在高浓度下产生明显更大程度的吸附。在模型硬淡水和软淡水中制备的样品的吸附等温线在测量的本体溶液浓度范围内彼此无法区分，但在中等蛋白质浓度下，硬水或软水的吸附比去离子水的吸附更广泛。流动电位测量表明，对于所有蛋白质组分和水硬度条件，在蛋白质本体浓度低至 0.03 μg/mL 时，吸附将二氧化硅 zeta 电位的净符号从负反转为正。这表明在不同的当地水硬度条件下，使用少量的种子提取物可以用油橄榄蛋白有效地改性沙子。最后，椭圆光度法表明，在这些模型淡水中冲洗时，油橄榄蛋白质不可逆地吸附，这表明改性砂在重复用于水过滤时将是稳定的。这些研究可能有助于为发展中国家设计一种简单、有效和可持续的水净化装置。
Motivated by the proposed use of cationic protein-modified sand for water filtration in developing nations, this study concerns the adsorption of Moringa oleifera seed proteins to silica surfaces. These proteins were prepared in model waters of varying hardness and underwent different levels of fractionation, including fatty acid extraction and cation exchange chromatography. Adsorption isotherms were measured by ellipsometry, and the zeta potentials of the resulting protein-decorated surfaces were measured by the rotating disk streaming potential method. The results indicate that the presence of fatty acids has little effect on the M. oleifera cationic protein adsorption isotherm. Adsorption from the unfractionated extract was indistinguishable from that of the cationic protein isolates at low concentrations but yielded significantly greater extents of adsorption at high concentrations. Adsorption isotherms for samples prepared in model hard and soft fresh waters were indistinguishable from each other over the measured bulk solution concentration range, but adsorption from hard or soft water was more extensive than adsorption from deionized water at moderate protein concentrations. Streaming potential measurements showed that adsorption reversed the net sign of the zeta potential of silica from negative to positive for all protein fractions and water hardness conditions at protein bulk concentrations as low as 0.03 μg/mL. This suggests that sands can be effectively modified with M. oleifera proteins using small amounts of seed extract under various local water hardness conditions. Finally, ellipsometry indicated that M. oleifera proteins adsorb irreversibly with respect to rinsing in these model fresh waters, suggesting that the modified sand would be stable on repeated use for water filtration. These studies may aid in the design of a simple, effective, and sustainable water purification device for developing nations.