Lentinan greatly enhances the dispersibility of single-walled carbon nanotubes in water and decreases the cytotoxicity

• SWNTs were successfully dispersed in water by Lentinan in a helical manner.
• Lentinan and SWNTs formed composite through hydrophobic interaction.
• The cytotoxicity of SWNTs greatly decreased by forming composite with Lentinan.

Single-chain Lentinan (s-LNT) was found to efficiently disperse single-walled carbon nanotubes (SWNT) in water. Raman spectroscopy, atomic force aicroscopy (AFM), scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), and energy dispersive X-ray spectroscopy demonstrated the formation of SWNTs/s-LNT composites through hydrogen-bonding and hydrophobic interactions between SWNTs and s-LNT. When adding DMSO or NaOH into the aqueous solution of SWNTs/s-LNT, SWNTs precipitated out, suggesting that hydrogen-bonding was broken and SWNTs were released from the composites. More interestingly, helical wrapping structures of s-LNT on the surface of SWNTs were observed by AFM and HRTEM. It can be explained as follows: the water-soluble s-LNT chains wrapped on the surface of hydrophobic SWNTs in a helical manner, endowing the water-solubility of SWNTs. Moreover, the SWNTs/s-LNT remarkably improved the cell viability in contrast to SWNTs in vitro test. This work provided an alternative method by which hydrophobic SWNTs were successfully dispersed in water by the water-soluble beta-glucan LNT in a helical wrapping manner, which also enlarged the applications of LNT.