Spontaneous Immobilization of Liposomes on Electron-Beam Exposed Resist Surfaces

Abstract

We have found an interesting immobilization technique of liposomes on electron-beam exposed resist surfaces. The immobilized liposomes have been visualized by the atomic force microscope and have shown well-organized three-dimensional physical structures, in which the liposomes maintain their shapes and sizes similar to those of the original design in prepared solution. The immobilization is based on a strong static charge interaction between the resist surface and the liposomes. Further experiments show that very strong charge in the surfaces produces the firm immobilization of the liposome. We believe these findings can be related to various liposome applications such as drug delivery system, electrochemical or biosensors, and nanoscale membrane function studies.

Formation of an intact liposome layer adsorbed on oxidized gold confirmed by three complementary techniques: QCM‐D, AFM and confocal fluorescence microscopy

“…Jung et al [9] used an amino-coupling method followed by the fabrication of a self assembled monolayer, a thiol-gold binding method and a charge interaction with a polymer resist deposited on the gold. Kim et al [10] found spontaneous binding of liposomes on electron beam exposed resist upon gold. Xu and Cheng [11] incorporated octadecanethiol on the vesicles to ensure firm attachment onto the gold surface.…”

“…This is why several authors use silicon wafers or mica to adsorb liposomes for AFM studies, in spite of using goldcoated quartz crystals in the QCM-D measurements. [10,21] In the present case, we decided to also use gold-coated quartz in the AFM measurements to avoid using different supports for different measurements, and by a careful analysis of the AFM images we were able to identify intact liposomes whose sizes were larger than that of the gold features. Finally, by encapsulating suitable fluorophores into the liposomes, we used LSCFM to obtain information on the conditions that led to rupture of the liposomes.…”

Stretched polymer nanohairs by nanodrawing

“…Simply, the operability of the stretched nanohairs can be given by (1) where W 12 (23) and A 12(23) are the work of adhesion and surface area at the polymer/substrate (mold/polymer) interface, respectively. The physical interpretation of r is the adhesion energy ratio at the interface, which should be close to unity for nanodrawing of the pre-formed nanostructures.…”

“…Alternatively, the surface of a mold has been treated with a fluorine-containing self-assembled monolayer (fluorination). 22,23 By contrast, use of a mold with high surface tension results in the delamination of a thin layer by a substantial difference in adhesive force between the mold/film interface (W 12 ) and the film/substrate interface (W 23 ). Based on this concept, a number of detachment-based lithographies have been introduced using different mold and film materials.…”

Electrochemical biosensors at the nanoscale

“…There are many strategies to embed receptor groups that recognize specific molecules in the transducer layer to guarantee selectivity and sensitivity. 25 A paradigm for nanobiosensors that can be miniaturized and integrated to produce intelligent analysis systems in numerous biotechnology applications has been sought for years [26][27][28][29] and the tremendous potential of highly sensitive electronic detection of biomolecules by nanoscale biosensors has been demonstrated for genomics 30,31 and proteomic 25,32 applications.…”