In Situ AFM Imaging of Adsorption Kinetics of DPPG Liposomes: A Quantitative Analysis of Surface Roughness

Abstract

The adsorption of intact liposomes on surfaces is of great importance for the development of sensors and drug delivery systems and, also, strongly dependent on the surface roughness where the liposomes are adsorbed. In this paper, we analyzed, by using atomic force microscopy in liquid, the evolution of the morphology of gold surfaces and of poly(allylamine hydrochloride) (PAH) surfaces with different roughness during the adsorption of liposomes prepared with the synthetic phospholipid 1,2-dipalmitoyl-sn-glycero-3-[phospho-rac-(1-glycerol)]. Our results reveal the following. On smooth surfaces of Au only and Au with PAH, the liposomes open and deploy on the substrate, creating a supported-lipid bilayer, with the opening process being faster on the Au/PAH surface. On rough substrates of Au coated with polyelectrolyte multilayers, the liposomes were adsorbed intact on the surface. This was corroborated by power spectral density analysis that demonstrates the presence of superstructures with an average lateral size of 43 and 87 nm, in accordance with two and four times the mean liposome hydrodynamic diameter of about 21 nm. In addition, this work presents an adequate and effective methodology for analysis of adsorption phenomena of liposomes on rough surfaces.

Simplifying Molecular Transport in Polyelectrolyte Multilayer Thin Films

“…[ 8–12 ] The ability to tune the PEM's architecture with nanometer precision is very promising aspect for using them in biomedical applications. Understanding the molecular dynamics of the participating species, either in situ [ 13–21 ] or ex situ, [ 22–26 ] is useful to further tune the PEM architecture for specific applications. When it comes to bio‐sensing and drug‐delivery applications, the bulk properties of PEM films play a significant role in their optimal functionality.…”

Changes in Mechanical Properties of Vesicles by Mucin in Aqueous Solution

“…After the adsorption, the heights and the widths of most bumps were up to 10 nm and 190 ± 60 nm, respectively ( Figure 2 b). The roughness was calculated with the root-mean-square, as suggested in Table 1 [ 31 ]. The difference in the flatness was clearly observed between the two images.…”