(741c) Tethered Bilayer Liposome Nanoparticle Microarray for Sensing Cell-Lipoplex Interactions

Targeted lipids-based (lipoplex) nanoparticles have been recognized as a promising approach for selected delivery of anti-cancer drugs and genes. Targeting two or more antigens on the same target cells can further enhance the therapeutic efficacy for personalized medicine because it may greatly reduce the off-targeting caused side effects. In addition, the simultaneous targeting of two or more cell surface antigens may lead to synergistic responses in the disease treatment. However, design and evaluation of such complicated multifunctional nanocarriers is not an easy task. It requires good understanding and quantification of cell-lipid nanoparticle interactions. Current analytical methods such as flow cytometry and anitigen microarray either require a large number of cells or cannot provide precise prediction of cell-nanoparticle interactions. In this study, we demonstrate a new microarray method based on tethered bilayer liposome nanoparticles. Bilayer liposome nanoparticles (tBLNs) were tethered on a mixed self-assembled monolayer (SAM) with a thiolipid. These tethered configurations were analyzed by fluorescence microscopy, atomic force microscopy (AFM) in the liquid environment and electrochemical impedance spectroscopy (EIS). The fluorescence microscopic images showed the formation of tBLN on a SAM-modified area patterned with a polydimethylsiloxane (PDMS) stamp. The tethered BLN on a planar surface was conjugated with therapeutic targeting antibodies. The multi-antibody conjugated tBLNs, also called immuno-liposomes (ILs), were demonstrated by using multi-color imaging of fluorescence microscopy. The AFM images showed that stable tBLNs were formed with some ellipsoidal liposomes with diameters ranging from 50 to 500 nm, similar to lipoplex nanoparticles used in drug and gene therapy. The EIS measurements showed the small semicircular shape at high frequencies disappeared on the Cole-Cole plot. Also, there was a large semi-circle covering a broad range of frequency with a tail near the low frequency end. The EIS measurement, together with AFM and fluorescence microscopy, is used as an analytical tool to study the cell-IL interactions on the tBLN microarray.