Nanostructured biomaterials have recently received much attention due to their large surface area and the higher degree of biological plasticity compared to micro scale or macro scale surface structures.

Semi conducting nanotubes can be produced from bacteria by biological means rather than chemical. These nanotubes have electrical and photoconductive properties and this property can be applied in electronics as well as other fields of material science to create new nanoelectronic devices having less costly and eco-friendly materials. For example the photoactive arsenic-sulfide nanotubes produced by the bacteria behave as metals with electrical and photoconductive properties and these properties may also provide novel functionality for the next generation of semiconductors in nano and opto electronic devices.

Applying a magnetic field to ferrofluids leads to a significant increase in viscosity, but the phenomenon has yet to find technological exploitation because of the thinning caused by even weak shear flows. The addition of plant-virus-derived nanotubes to a commercial ferrofluid can give rise to a dramatic enhancement in magneto viscosity and a suppression of shear thinning. This is due to a marked tendency for the magnetic nanoparticles to form scaffolding at the outside surface of the virus nanotubes forming.

Ion channels are protein macromolecules that form biological nanotubes in the cell membrane of living cells and these regulate all electrical activities of human nervous system, including communications between cells and the influence of hormones and drugs on cell function. The ion-selective, synthetic nanotubes which mimic biological ion channels have significant implications for the future treatment of bacteria, diseases, and as ultra sensitive biosensors. Synthetic nanotube made from carbon atoms selectively allows monovalent cations to move across and rejects all anions. The cation-selective nanotube mimics some of the salient properties of biological ion channels. The synthetic nanotube has a high sodium conductance.

The traditional treatments for leishmaniasis involve toxic drugs that are not completely efficient and generate life-threatening adverse side effects. The use of biological nanotubes that are biocompatible and at the same time have the capacity to transport, selectively penetrate infected cells and deliver compounds will destroy the parasite causing leishmaniasis. This method will open new exciting possibilities for the use of biological nanotubes for drug delivery and the treatment of tropical diseases such as Leishmaniasis or Chaga’s disease.

Researchers from China and the UK report a novel self-assembly approach to generate nanotubes from viral capsid proteins for applications in biotechnology. Recombinant DNA technology was used to express viral capsid proteins of the cucumber mosaic virus from E. coli bacteria. The resulting densely packed misfolded protein particles were separated, purified and solubilised using urea. The proteins, denatured by the urea, were refolded and then mixed with double-stranded DNA which act as templates with the capsid proteins assembling around them into helical assemblies.

Biological molecules as scaffold

Researchers from CNRS and the University of Rennes report that therapeutic peptide, lanreotide could serve as a scaffold for the spontaneous formation of silica nanotubes by simple mixing with a silica precursor in water. These hybrid tubes consist in a perfect helical assembly of molecules of the drug, the internal and external surfaces of which are covered with two thin and uniform layers of silica. The tubes are several micrometers long and aligned in fibers of a few millimeters. Their organization is thus controlled hierarchically over more than 6 orders of magnitude. A slow technique was developed by researchers which enabled the coating of silica on nanotubes of biological molecules formed in water. The silica deposit favored the gradual lengthening of the organic nanotube, the new tip of which could then serve again as a scaffold for further silica deposits. This recurrent process ensured both control of the organization at a molecular scale and the growth of an organic scaffold as the mineral was deposited.