Universal Method to Transfer Membrane-Templated Nano-Objects to Aqueous Solutions

Abstract

A wide range of nano-objects are synthesized by combining template synthesis, using polycarbonate membrane as template, with different material deposition methods. The resulting nanostructures varied from robust inorganic gold nanowires grown by electrodeposition to rigid polypyrrole nanotubes synthesized by chemical polymerization and softer nanotubes made of different combinations of synthetic and natural polyelectrolytes fabricated by layer-by-layer (LbL) assembly. The morphology of these various nano-objects is characterized prior to and after their immersion in water, revealing that the rigidity degree of LbL nanotubes strongly decreases after being in contact with water, leading to highly swollen and flexible nanotubes in aqueous solution that tend to stick to any surface and are very difficult to collect and disperse quantitatively in aqueous solution. Different processes to collect these nano-objects and disperse them in aqueous medium for further analysis and application were then studied. Among them, a method based on simple filtration of nanotubes in the presence of a powdered dextran adjuvant leads to the quantitative collection and dispersion in water of all types of tested cylindrical nano-objects. This universal method to efficiently collect membrane templated nano-objects paves the way to further characterization of a large variety of nanotubes in aqueous solution and to their potential use as cargo nanocarriers or as nanoreactors.

Uptake of Long Protein-Polyelectrolyte Nanotubes by Dendritic Cells

“…In addition, whereas PAH/PSS based tubes partially preserve their geometrical features, OVA-containing nanotubes are completely broken into pieces and strongly swollen after exposure to water. In a former publication, 30 we introduced a rigidity index to compare the morphology of the nanotubes in a more quantitative manner. The rigidity index, ⟨R EE 2 ⟩/L 2 , is defined as the ratio between the root-mean-square of the end-to-end distance (R EE ), and the square of the average contour length (L).…”

“…This result shows that, when dispersed in an aqueous solution, the tubes soften due to swelling, then deform and break more easily for biomacromolecule-based assemblies, a trend in good agreement with a previous report. 30 The wall thickness of the LbL tubes of Figure 1 was calculated after gas flow porometry measurements and compared against our observations from Scanning Transmission Electron Microscope (STEM) images. Based on gas flow porometry we calculated the pore size of the membrane before and after LbL deposition, leading to an estimation of the wall thickness of the tubes, d wall (Table 2).…”

“…We used a previously reported protocol to transfer the LbL nanotubes into an aqueous solution and avoid agglomeration. 30 Briefly, 20−25 mg of dextran powder was dispersed in a few mL of dichloromethane and filtered over a PET membrane to form a porous dextran cake. Separately, 1 cm 2 of LbL-modified PC membrane was dissolved in an equal volume of dichloromethane and mixed with 20−25 mg of dextran powder before being filtered on top of the dextran cake.…”

“…We used a previously reported protocol to transfer the LbL nanotubes into an aqueous solution and avoid agglomeration . Briefly, 20–25 mg of dextran powder was dispersed in a few mL of dichloromethane and filtered over a PET membrane to form a porous dextran cake.…”

Protein Microtube Motors with a Pt Nanoparticle Interior and Avidin Exterior for Self-Propelled Transportation, Separation, and Stirring

“…Cylindrical hollow structures in micrometer-scale “microtubes” can perform different tasks in three separate structural parts: the inner surface, tube wall, and outer surface. Wet-template-assisted synthesis using alternate layer-by-layer (LbL) assembly in a track-etched polycarbonate (PC) membrane is a useful procedure to create smart microtubes comprising soft materials. − Aqueous solutions of biologically active macromolecules such as DNAs, polypeptides, − polysaccharides, , and proteins ,,− are filtered through the PC membrane and are deposited onto the pore walls. Subsequently, dissolution of the template yields uniform hollow cylinders.…”