Nanomembrane – Real Two Dimensional Nanostructures


Artistic view of biological nanomembrane with artificial ions channels

Entire life on the Earth relies on nanomembranes. Therefore, it is not a surprise that biological nanomembranes or cell membranes are the most complex group of nanomembranes. With thickness below 100 nm, the biological nanomembranes separate the cytoplasm of the living cell from its environment and at the same time enable an active interaction between the cytoplasm and the environment. Today’s science is far from fully understating the exchange mechanisms across the biological nanomembrane.

 

Nanomembranes are defined as freestanding structures with a thickness in the range of 1 – 100 nm and an extremely large aspect ratio, of at least a few orders of magnitude. To illustrate how thin nanomembranes are, let us compare a 10 nm-thick nanomembrane with the 0.3 nm diameter of an atom: the nanomembrane I only 30 atomic layers thick! On the other hand, such structure can have a very large surface: the surface area a 10-40 nm-thick nanomembrane can be several square centimetres large! Being quasi-two dimensional, nanomembranes exhibit new and unusual properties, naturally not found in materials with macroscopic size. This makes nanomaterials irreplaceable in various applications such as sensing, optics, plasmonics, biomedicine, and many more.

 

To be applied, nanomembranes have first to be functionalized. Today, there are four different approaches to functionalization: lamination of nanomembranes (stacking of nanometre thin layers of different materials), introduction of nanoparticle fillers into the nanomembrane scaffold, nanomembrane surface sculpting and modification through patterning (including formation of nanohole arrays and introduction of ion channels similar in function to those in biological nanomembranes). As these approaches can also be combined, practically unlimited opportunities for functionalization of nanomembranes open up for. The time when nanomembranes more complex then the biological membranes will be produced, but with mechanical properties surpassing their natural counterparts, is not far from today and researchers at BioSense Institute are very active in this field.

 

A special focus in BioSense research is the development and functionalization of nanomembranes for sensing applications. Due to very large aspect ratio of nanomembranes, such sensors imply very large active areas for a small volume, resulting in high sensitivity and miniature size of the final devices. This quality of nanomaterials is expressed in 0-D nanostructures (dots and cages) and 1-D structures (nanowires, nanotubes and nanochannels), as well as in 2-D structures like ultrathin films and nanomembranes. BioSense researchers develop various nanostructures as sensing elements which will allow the detection of ultra small concentrations of environmental pollutants, additives or toxins in the food chain, as well as the development of various sensors of complex analytes such as chemical and biochemical substances.

SEM picture of artificial nanomembrane. The nanomembrane size is 2 x 3 mm, thickness is 7 nm and the hole diameter is 50 nm