Comparative investigation on the sizes and scavenger receptor binding of human native and modified lipoprotein particles with atomic force microscopy

BACKGROUND The size and receptor-binding abilities of plasma lipoproteins are closely related with their structure/functions. Presently, the sizes of native lipoproteins have been measured by various methods including atomic force microscopy (AFM) whereas the sizes of modified lipoproteins are poorly determined and the receptor-binding ability of lipoproteins is less detected and compared at the nanoscale. METHODS Here, AFM was utilized to detect/compare the size and scavenger receptor-binding properties of three native human lipoproteins including high-density lipoprotein, low-density lipoprotein (LDL), and very low-density lipoprotein, and two modified human lipoproteins including oxidized and acetylated LDL, as well as bovine serum albumin and their antibodies as negative and positive controls, respectively. RESULTS AFM detected that the sizes of these lipoproteins are close to the commonly known values and the previously-reported AFM-detected sizes and that native and modified LDL have different height/size. AFM also revealed that the CD36-binding abilities of the five lipoproteins are different from one another and from their SR-B1-binding abilities and that the anti-CD36/SR-B1 antibodies as positive controls have strong CD36/SR-B1-binding abilities. CONCLUSIONS The data provide important information on lipoproteins for better understanding their structures/functions. Moreover, the data certify that besides size measurement AFM also can visualize receptor-lipoprotein binding at the nanoscale, as well as antigen-antibody (scavenger receptors and their antibodies) binding.