Abstract
A novel and facile method was developed to produce hybrid graphene oxide (GO)–polyelectrolyte (PE) capsules using erythrocyte cells as templates. The capsules are easily produced through the layer-by-layer technique using alternating polyelectrolyte layers and GO sheets. The amount of GO and therefore its coverage in the resulting capsules can be tuned by adjusting the concentration of the GO dispersion during the assembly. The capsules retain the approximate shape and size of the erythrocyte template after the latter is totally removed by oxidation with NaOCl in water. The PE/GO capsules maintain their integrity and can be placed or located on other surfaces such as in a device. When the capsules are dried in air, they collapse to form a film that is approximately twice the thickness of the capsule membrane. AFM images in the present study suggest a film thickness of approx. 30 nm for the capsules in the collapsed state implying a thickness of approx. 15 nm for the layers in the collapsed capsule membrane. The polyelectrolytes used in the present study were polyallylamine hydrochloride (PAH) and polystyrenesulfonate sodium salt (PSS). Capsules where characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), dynamic light scattering (DLS) and Raman microscopy, the constituent layers by zeta potential and GO by TEM, XRD, and Raman and FTIR spectroscopies.
Highlights
The past decades have witnessed explosive growth in research on low-dimensional carbon forms with graphene and carbon nanotubes in the forefront [1,2,3]
Using layer-by-layer technique (LbL), we explored the assembly of exfoliated graphene oxide (GO) into 3D structures and developed micrometre-sized capsules on the basis of GO and polyelectrolytes using chicken erythrocyte cells as templates
We have shown that 3D micrometre-sized objects in the form of capsules can be fabricated on the basis of the LbL assembly of GO and polyelectrolytes on top of fixed erythrocyte cells as templates
Summary
The past decades have witnessed explosive growth in research on low-dimensional carbon forms with graphene and carbon nanotubes in the forefront [1,2,3]. Bi- and few-layer graphene are difficult to work with in soft matter or wet chemical applications because of dispersibility issues and the tendency to form multi-layered agglomerates, which begin to acquire the properties of graphite [9,10,11] Because of these difficulties, most studies of graphene, whether for layered assembly or other investigations, have been performed on graphite oxide or its exfoliated form, graphene oxide (GO), which bears a mix of sp and sp hybridized carbons in an overall planar structure. The use of GO sheets in the formation of hierarchical structures and assemblies is a subject of current interest, and if done by procedures involving wet chemical techniques, offers much potential for the development of advanced and composite layered materials
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