McIntire T M, Brant D A
Department of Chemistry, University of California, Irvine 92697-2025, USA.
Int J Biol Macromol. 1999 Dec 1;26(4):303-10. doi: 10.1016/s0141-8130(99)00097-5.
Samples of kappa-carrageenan, iota-carrageenan, and synthetic amylose have been examined by atomic force microscopy (AFM). All samples were spray deposited from aqueous solutions onto freshly cleaved mica, air dried, and imaged in air using noncontact atomic force microscopy (NCAFM). Images of single stranded amylose and carrageenan are presented. At relatively low polymer concentrations in the presence of NaCl iota-carrageenan formed circles that appear to be predominantly head-to-tail associated unimeric duplex (double stranded) structures. At higher iota-carrageenan concentrations the polymer forms circles and aggregates that appear to involve dimeric duplex structure. Direct comparison of synthetic amylose molecular weights determined from NCAFM images with results from solution measurements showed that NCAFM provides an excellent way to measure amylose molecular weight and molecular weight distribution. It is shown that synthetic amylose is single stranded in aqueous solution and that the chain length distribution is broader than the Poisson distribution anticipated from polymerization theory.
已通过原子力显微镜（AFM）对κ-卡拉胶、ι-卡拉胶和合成直链淀粉的样品进行了检测。所有样品均从水溶液中喷雾沉积到新劈开的云母上，空气干燥后，使用非接触式原子力显微镜（NCAFM）在空气中成像。展示了单链直链淀粉和卡拉胶的图像。在NaCl存在下，聚合物浓度相对较低时，ι-卡拉胶形成的圆圈似乎主要是头对尾相连的单聚体双链（双链）结构。在较高的ι-卡拉胶浓度下，聚合物形成圆圈和聚集体，似乎涉及二聚体双链结构。通过NCAFM图像确定的合成直链淀粉分子量与溶液测量结果的直接比较表明，NCAFM为测量直链淀粉分子量和分子量分布提供了一种极好的方法。结果表明，合成直链淀粉在水溶液中是单链的，并且链长分布比聚合理论预期的泊松分布更宽。
