Researchers at Stanford University have developed a technique to prepare conductive single-walled carbon nanotube films for biotechnology applications by depositing them on substrates coated with poly-L-lysine.
Poly-L-Lysine
Poly-L-Lysine is a synthetic amino acid chain that is positively charged and widely used as a coating to enhance cell attachment and adhesion to both plastic ware and glass surfaces. Poly-L-Lysine is normally used to cover tissue culture plates to help biological cells better stick to the plates. The molecular weight of Poly-L-Lysine can vary significantly with lower molecular weight (30,000 Da) being less viscous and higher molecular weight (>300,000 Da) having more binding sites per molecule.
Poly-L-Lysine is used to coat tissue culture plastic ware for enhanced cell attachment and adhesion. Coated surfaces will often improve cell attachment in reduced or serum-free conditions.
SWCNT
SWNTs on the market, regardless of which manufacturer produces them have 90% or 99% SWNTs content with Outer Diameter 1-2nm, inner Diameter 0.8-1.6nm and Length: 3-30um.
Single-walled carbon nanotubes have a wide range of unique electrical, mechanical and chemical properties and are thus promising for organic electronic applications, such as thin-film transistors, conducting electrodes and biosensors.
Nanostructures are used by researchers in biotechnology due to their exceptional electronic properties and ability to be functionalized.
SWCNTs have been used in bioelectronic devices, like drug delivery carriers and even scaffolds for tissue engineering. Researchers functionalize carbon nanotubes to make them more biocompatible, but the procedure is sometimes tedious and not always very efficient. But the present technique is simple and quick.
Functionalized surface
By soaking substrates, such as glass slides or silicon oxide wafers, in a solution of poly-L-lysine and depositing spin-coated carbon nanotubes onto the surface of the substrates hybrid material with a conducting surface can be created. The process can also be tuned to deposit specific amounts of SWCNTs on the slides and wafers.
As evident from scanning electron microscopy studies the SWCNT-PLL hybrid materials were found to be biocompatible by way of measuring cellular morphology in respect of metabolism and health.
Researchers found the SWCNTs to have little toxicity by monitoring mitochondrial activity in the cells and the cells had regular features or protrusions and retained a healthy and elongated shape.
Applications
Development of more biocompatible SWCNT surfaces will be useful in the field of bioelectronics and for developing conductive surfaces for biomedical applications.