Imaging and force measurement of LDL and HDL by AFM in air and liquid

• Published in: FEBS open bio 2015-01, Vol.5 (1), p.276-282
• Main Authors: Gan, Chaoye, Ao, Meiying, Liu, Zhanghua, Chen, Yong
• Format: Article
• Language: English
• Subjects: Adhesive force; Adhesives; Apolipoproteins; Atomic force microscopy; Atomic force microscopy (AFM); Biomechanics; Capsids; Cardiovascular disease; Cholesterol; Coronary vessels; High density lipoprotein; High-density lipoprotein (HDL); Lipoproteins; Liposomes; Low density lipoprotein; Low-density lipoprotein (LDL); Mechanical properties; Microscopy; Morphology; NMR; Nuclear magnetic resonance; Silicon nitride; Software; Standard deviation; Studies; Young's modulus
• ISSN: 2211-5463; 2211-5463
• DOI: 10.1016/j.fob.2015.03.014

•AFM measured the equivalent diameters of LDL (∼22.7nm) and HDL (∼14.4nm) in PBS.•AFM detected the mean Young’s moduli of LDL (∼0.39GPa) and HDL (∼0.47GPa) in PBS.•AFM detected the mean adhesive forces of LDL (∼0.19nN) and HDL (∼0.15nN) in PBS.•AFM detected much larger sizes of Young’s moduli and adhesive forces of LDL/HDL in air. The size and biomechanical properties of lipoproteins are tightly correlated with their structures/functions. While atomic force microscopy (AFM) has been used to image lipoproteins the force measurement of these nano-sized particles is missing. We detected that the sizes of LDL and HDL in liquid are close to the commonly known values. The Young’s modulus of LDL or HDL is ∼0.4GPa which is similar to that of some viral capsids or nanovesicles but greatly larger than that of various liposomes. The adhesive force of LDL or HDL is small (∼200pN). The comparison of AFM detection in air and liquid was also performed which is currently lacking. Our data may provide useful information for better understanding and AFM detection of lipoproteins.