SAXS-revealed nanostructures of light-responsive poly(ethylene glycol)-grafted liposomes

Chun-Jen Su^1*, Hua-De Gao², Hsien-Ming Lee², U-Ser Jeng^1,3

¹National Synchrotron Radiation Research Center, Hsinchu, Hsinchu, Taiwan
²National Synchrotron Radiation Research Center, Hsinchu, Taipei, Taiwan
³National Synchrotron Radiation Research Center, Hsinchu, National Tsing Hua University, Hsinchu, Taiwan

* Presenter:Chun-Jen Su, email:su.cj@nsrrc.org.tw

Nanomedicine and nano-drug delivery system is a relatively new and rapidly developing field, and liposomes are the most common and well-studied nanocarriers for targeted drug delivery. This study selected light-responsive membrane lytic peptides as trigger-responsive agents for liposome drug-release systems. The nanostructures of the complex PEGylated liposome will be investigated using small-angle X-ray scattering technology.
A 5-layer model is developed for the SAXS data analysis, to resolve the nanostructures of the complex vesicles of PEGylated phospholipids. The proposed model employs five Gaussian functions to represent: one central layer of the lipid-tail zone in the liposome vesicles, which is sandwiched by two layers of phosphate head groups of the lipids, and further capped by two outermost layers of PEG of the unilamellar vesicle bilayer of the liposomes. The 5-layer model could fit decently the SAXS data, and reveal the thickness and electron-density of each sublayer of the PEG-grafted vesicle bilayer of the liposome. The structural changes observed are further correlated to the drug releasing efficiency observed, providing a structural basis for the design of controlled drug delivery.

Keywords: SAXS, PEGylated liposome, membrane structure, membrane structure